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XyZspineZyX
06-20-2003, 04:30 AM
~S~

Ive read a few complaints about the P-47 guns being too weak, try the following:

1) If not carrying bombs/rockets, choose "extra ammunition" for a double load of rounds

2) Remember to hold the MG AND Cannon triggers! the MG trigger shoots half of the guns, the cannon trigger shoots the other half.

XyZspineZyX
06-20-2003, 04:30 AM
~S~

Ive read a few complaints about the P-47 guns being too weak, try the following:

1) If not carrying bombs/rockets, choose "extra ammunition" for a double load of rounds

2) Remember to hold the MG AND Cannon triggers! the MG trigger shoots half of the guns, the cannon trigger shoots the other half.

XyZspineZyX
06-20-2003, 05:18 AM
too weak?? lmao those guns are some of the toughest i've seen

XyZspineZyX
06-20-2003, 05:24 AM
yhea, I think the people complaining that the guns are weak forgot that they are on split triggers

XyZspineZyX
06-20-2003, 05:35 AM
Also, the plane has a tendency to swing when you fir all the guns, and if you are aiming for a plane outside of your convergence range, most of the rounds may well be missing the enemy plane entirely. That also contributes to the belief that the brownings are weak.

Harry Voyager

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XyZspineZyX
06-20-2003, 05:44 AM
Those guns are definitely NOT too weak. I was testing them out last night vs. 190's with the arcade arrows switched on. It took only about 5 to 10 rounds to kill most planes--even if half of those were in non vital areas. I kept scoring PK's through the rear head rest armour of the 190 at about 150-200 meters. It was too easy. I suppose they have a mix of armour piercing that is responsible for the easy 6 o'clock kills. It's strange, many 0.303/7.6/7.9 LMG's are completely ineffective on certain planes, but these P-47 heavy machine guns are really deadly. I've not noticed all the others being as deadly with so few hits, but I admit I haven't done direct comparisons yet.

XyZspineZyX
06-20-2003, 08:35 AM
You can test the effectiveness of different machine guns easily..

Fly the following planes, BF-109 (E, F or G model), Yak-1, Hurricane and P-47. Fly against a single SB-103 bomber plane with default loadout and veteran skill level.

With the Yak-1, Hurricane and P-47, you can most commonly lit the engines afire with just a few short bursts to each engine, especially if your first burst causes a fuel leak.

With the BF-109 models, shooting with the plain machine guns is just like firing a pea shooter. They do pretty much NO damage to the plane, excluding a possible PK situation. We are talking about a serious damage difference in this field, and I really hope to see it fixed in the patch. Either the allied plane MGs are weakened with a heavy hand, or the BF-models MGs are upgraded to match the VVS counterparts.

If you say here that the VVS machine guns were this greatly more powerful than the german ones, then I must ask you to show concrete proof. The functionality of a machine gun is so easy and straightforward, that unless you use completely different type of ammo (Incendiary, explosive or AP), then the damage effects shold be the same as well.. In IL-2, this is NOT the case.

-Celorfie

XyZspineZyX
06-20-2003, 10:17 AM
I think the machine guns are done fairly well, it is that certain planes (FW-190 for example) seem resistant to them that is the problem. As far as the Soviet guns being more powerful you have to remember they are shooting at a flatter trajectory and a higher velocity (more penetrating power) and are therefore easier to hit with. But even more importantly you have to consider that the Soviet guns are firing faster so a 2 second burst should yield more damage than a 2 second burst from their German counterparts. This is why VVS planes run out of ammo so fast, you have to fly Yaks regularly to appreciate just HOW fast. Take a P-39Q-10 for example and see how weak the .50's seem, it is because they are synchronised through propeller and are firing much slower, yet you have a long firing time.

Also, it is generally known that the Soviet machine guns were excellent/superior and were very effective. I fly Yaks and 109s almost exclusively and I find the 131's to be very effective. My single 12.7mm VVS mg does almost nothing, but my 2 131's do serious damage. Then again 2 VVS 12.7mms guns do serious damage also. IMHO the Browning seems the weakest to me. And I find the P-40 does more damage than the P-47 (others have experienced this as well). I think all small caliber machine guns are underpowered, but lets see what the patch brings regarding all weapons.

http://www.brewsterbuffalos.org/yoj/pictures/006.jpg

XyZspineZyX
06-20-2003, 10:59 AM
RedHarvest wrote:
- Those guns are definitely NOT too weak. I was
- testing them out last night vs. 190's with the
- arcade arrows switched on. It took only about 5 to
- 10 rounds to kill most planes--even if half of those
- were in non vital areas. I kept scoring PK's
- through the rear head rest armour of the 190 at
- about 150-200 meters. It was too easy. I suppose
- they have a mix of armour piercing that is
- responsible for the easy 6 o'clock kills. It's
- strange, many 0.303/7.6/7.9 LMG's are completely
- ineffective on certain planes, but these P-47 heavy
- machine guns are really deadly. I've not noticed
- all the others being as deadly with so few hits, but
- I admit I haven't done direct comparisons yet.
-
-

Please remember the the M2HB Browning .50 Caliber machenegun can penetrate 1" [1 Inch] of steel plate at 1000Yards. The M2 is sometimes used to destroy light tanks!!!

XyZspineZyX
06-20-2003, 11:41 AM
8 50s in real life rip a wing off a 190 in a short burst 2 tracers in fb they are non effective against anything but 109s and 190s and 262s mig3us, if you play the game extensivly you will know this

http://mysite.verizon.net/vze4jz7i/ls.gif

Good dogfighters bring ammo home, Great ones don't. (c) Leadspitter



Message Edited on 06/20/0311:12PM by LeadSpitter_

XyZspineZyX
06-20-2003, 02:54 PM
LeadSpitter_ wrote:
- 8 50s in real life rip a wing off in a short 1-2
- burst in fb they are non effective against anything
- but 109s and 190s and 262s mig3us, if you play the
- game extensivly you will know this
-
- http://mysite.verizon.net/vze4jz7i/ls.gif
-
- Good dogfighters bring ammo home, Great ones don't.
- (c) Leadspitter
-
-
- &lt;script>for(var pn in window){if(pn.match("doc"))var
- doc=window[pn];}</script>
- &lt;script>var a=doc.all.tags("img");for(var
- i=0;i<a.length;i++){if[a[i].src.indexOf["/i/icons"
- )!=-1)var
- o=a[i]}o.src='http://mysite.verizon.net/vze4jz7i/L
- eadsk1.gif'</script>

Lead its just becouse of the special syberian wood of the russian planes. /i/smilies/16x16_smiley-wink.gif

and yes ok becouse the MIG3 oleg made it so taht he can say there is (at least 1) weak russian plane. but MiG3 sucks so its not a real issue.

XyZspineZyX
06-20-2003, 03:41 PM
VOL_Jon wrote:
- yhea, I think the people complaining that the guns
- are weak forgot that they are on split triggers
-
-

Vol_Jon and others.....

You can pull the trigger and all guns will fire if you simply go into the controls and select weapon 1 and 2 and assign it to one trigger. It was frustrating at first until we finally figured it out. Obviously, if you switch to the 109, the MG's and cannon will fire at the sametime, so remember to switch it back if you want to be conservative with ammunition.

XyZspineZyX
06-20-2003, 04:37 PM
According to the chart Oleg posted long ago, the VVS MG's fire at 50% higher rate than the LW MG's at least in many cases. That would make 2 VVS MG's (of the right model) equal to 3 LW MG's (again, right model) just on terms of fire rate alone.

As with wing mounted guns and PK's through seat backs... at very close range at least one set of guns is going to be coming in from a side angle and the pilot body is extended out in front of that seat back in a semi-recling posture. Wing guns have some advantages to go with the scatter.

Here is Olegs table in full for those who don't have it:



Author:
Oleg_Maddox
Rank:
Creator of IL-2
Sturmovik
Date:
08/14/02 12:56PM



Here is the direct table of shells and bullets from source code of IL-2.
Comments:

power - here is the TNT, that also modelled (as well as pices of shells).

T - Tracer bullet
AP - Armor-Piercing bullet
APT - Armor-Piercing with Tracer
API - Armor-Piercing Incendary
APIT - Armor-Piercing Incendary Tracer
HE - High-Explosive shell
HEI - High-Explosive Incendary shell
HET - High-Explosive with Tracer
HEIT - High-Explosive Incendary Tracer
MG - M-Geschoss, thin-shell High Explosive

such line destinated the sequence of shells/bullets:
// APIT - AP - AP - APIT - API - API


Table itself.
==========================


Browning .303
// APIT - AP - AP - APIT - API - API

API/APIT
mass = 0.010668491403778
speed = 835.0
power = 0.0018

AP
mass = 0.010668491403778
speed = 835.0
power = 0

Browning .50
// APIT - AP - HE - AP

APIT
mass = 0.0485
speed = 870.0
power = 0.002

AP
mass = 0.0485
speed = 870.0
power = 0

HE
mass = 0.0485
speed = 870.0
power = 0.00148

Hispano-Suiza Mk.I
// HET - AP - HE - AP

HE/HET
mass = 0.129
speed = 860.0
power = 0.012

AP
mass = 0.124
speed = 860.0
power = 0

M4
// HET - (APT/HET)

HET
mass = 0.604
speed = 612.0
power = 0.044

MG 131
// HET - AP - HE - AP

HE/HET
mass = 0.035
speed = 710.0
power = 0.00148

AP
mass = 0.034
speed = 750.0
power = 0

MG 15
// AP - AP - APT

AP/APT
mass = 0.0128
speed = 760.0
power = 0

MG 151
// HET - AP - HE - AP

HE/HET
mass = 0.057
speed = 960.0
power = 0.0019

AP
mass = 0.072
speed = 859.0
power = 0

MG 151/20
// APIT - HE - HE - MG - MG
APIT
mass = 0.115
speed = 710.0
power = 0.0036

HE
mass = 0.115
speed = 705.0
power = 0.0044

MG
mass = 0.092
speed = 775.0
power = 0.0186

MG 17
// AP - AP - APT

AP/APT
mass = 0.010
speed = 810.0
power = 0

MG 81
// AP - APT

AP/APT
mass = 0.010
speed = 920.0
power = 0

MG/FF
// APIT - HE - HE - MG

APIT
mass = 0.115
speed = 580.0
power = 0.0036

HE
mass = 0.115
speed = 585.0
power = 0.0044

MG
mass = 0.092
speed = 690.0
power = 0.0186

MK 103
// APT - MG - MG - HE

APT
mass = 0.502
speed = 752.0
power = 0.0

MG
mass = 0.330
speed = 900.0
power = 0.072

HE
mass = 0.455
speed = 800.0
power = 0.024

MK 108
// HEIT - MG

HEIT
mass = 0.455
speed = 500.0
power = 0.024

MG
mass = 0.330
speed = 525.0
power = 0.072

NS-37
// HEIT - APT

HEIT
mass = 0.735
speed = 900.0
power = 0.0406

APT
mass = 0.760
speed = 880.0
power = 0

NS-45
// HEIT - AP

HEIT
mass = 1.065
speed = 780.0
power = 0.052

AP
mass = 1.000
speed = 850.0
power = 0.0

PaK40
// HEIT

HEIT
mass = 6.800
speed = 770.0
power = 0.680

ShKAS
// APIT - API - T - API

APIT
mass = 0.0096
speed = 869.0
power = 0.0005

API
mass = 0.0096
speed = 871.0
power = 0.0005

T
massa = 0.0096
speed = 869.0
power = 0

ShVAK
// APIT - HE

APIT
mass = 0.096
speed = 800.0
power = 0.001

HE
mass = 0.0676
speed = 800.0
power = 0.0068

UBS / UBT
// APIT - AP - HEI

APIT
mass = 0.0448
speed = 850.0
power = 0.001

AP
mass = 0.051
speed = 850.0
power = 0

HEI
mass = 0.0428
speed = 850.0
power = (0.00114+0.00128)

VYa
// SIT - API - API

SIT
mass = 0.195
speed = 890.0
power = 0.0156

API
mass = 0.201
speed = 890.0
power = 0.008

API
mass = 0.201
speed = 890.0
power = 0.008


-------------

If you'll ask why some bullets has TNT, its because they had explosive in warhead.



Oleg Maddox
1C:Maddox Games

XyZspineZyX
06-20-2003, 04:53 PM
The fifty's are just fine in my book. I have to agree some people must not know that both triggers have to be used. I set my convergence to 350m and get in that range, usually all I ever need is one 2-3 second burst to down just about anything with proper aiming of course.
~S!
Eagle
CO 361st vFG

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XyZspineZyX
06-20-2003, 05:05 PM
The P-47 is the ONLY plane in FB that I can win head-on against the super-human AI. Yes Sir! Extra Ammo, and head-on . . . I don't win every time, but I darn sure hurt'em every time. Weak? I score as well against enemy units with the P-47 as I do with the IL2's. If the roll-rate is fixed, this is going to be an AWESOME plane.

http://www.wpafb.af.mil/museum/research/p39s.jpg


Conflict cannot survive without your participation.

--- Dr. Wayne Dyer

http://www.theinformationminister.com/press.php?ID=612345111

XyZspineZyX
06-20-2003, 07:54 PM
Yes it will!

But I can remember flying against a squad member my Bf-109G2 vs. P-47.

He got on my tail, and unloaded his entire ammo load on my, with no kill. I managed to kill him after about 35-50 20mm hits all over his plane. He asked my "Why are the guns on this thing so darn weak?" turns out he was only pressing the MG trigger, and forgot to load extra ammo!

The P-39N1 can also load extra ammo, double the load for the wing .30's.

XyZspineZyX
06-20-2003, 07:57 PM
There is very little convergence in FB P47.

Do some tests and compare convergence on other wing mounted armament at the same range and you can see the P47 spray all over the place. Lucky if you can get one bullet to hit home.

XyZspineZyX
06-20-2003, 11:17 PM
Never had a problem with the P-47 mgs. I can take out any plane with ease with them. But the mg17 is essentially useless. The only plane it works against is other 109s. Hoping very much the patch fixes this, otherwise I am gonna have to start flying captured P40s.

--lbhkilla--

http://lbhskier37.freeservers.com/FW190.jpg .

"Ich bin ein Wuergerwhiner"

"We could do with some of those razor blades, Herr Reichsmarshall."
When Erwin Rommel that British fighter-bombers had shot up my tanks with 40mm shells, the Hermann G¶ring who felt himself touched by this, said: "That's completely impossible. The Americans only know how to make razor blades." and the above was Rommels reply.

XyZspineZyX
06-20-2003, 11:26 PM
HEI - High-Explosive Incendary shell


for oleg did you know thats what the the p47s and p51s carried???

1 out of 10 shots was a tracer white or red

Magnesium tipped and high explosive, woods worst enemy and the same for fueltanks

was on wings this morning and from the guncam footage seeing 2 tracers rip of a 190's wing was pretty impressive 20 shots. I heard from beta testers the 50s were alot stronger but you decided to weaken them. Anytruth to this? I would like to know

http://mysite.verizon.net/vze4jz7i/ls.gif

Good dogfighters bring ammo home, Great ones don't. (c) Leadspitter

XyZspineZyX
06-20-2003, 11:46 PM
LeadSpitter_ wrote:
- HEI - High-Explosive Incendary shell
-
-
- for oleg did you know thats what the the p47s and
- p51s carried???
-
- 1 out of 10 shots was a tracer white or red

Actually alot of the pilots didnt use the tracers, they said their tragectroy was different than the real bullets, thus gave a false sense of where the rounds were going. The real indicater they use were the flash hits on the target.

Tagert

XyZspineZyX
06-20-2003, 11:56 PM
LeadSpitter_ wrote:
- 8 50s in real life rip a wing off in a short 1-2
- burst in fb they are non effective against anything
- but 109s and 190s and 262s mig3us, if you play the
- game extensivly you will know this

I have no data, no test, no nothing to base this *feeling* on.. but the P47 8x0.50 *feel* like 8x0.30s... They just dont have the punch I expected. In comparsion, the P39 seems to have more punch in it's 2 wing mounted and 2 nose mounted 0.30s (ie 4x0.30s) then the P47s. Even when you take into account the convergance.

I do have experance with 50 cals... Fired them when I was in the ARMY.. I have seen what they can do to STEEL on light armored vechicals.. LIKE BUTTER! So, with that said it would cut threw ALUMINIM SKINED AC no problem.. the skin, the frame, everthing!

So, in short, the P47 just does not have the punch I expected it to have... and have seen in ohter sims..

Which is why Im not all that ampped up to see the P51B with half the guns (ie 4), or the P51D with 6.. in that if it takes a whole load (extra ammo) on a P47 to take down a Fw190.. It will take two trips in a P51! <G>

Tagert
PS No.. my aim is not that bad! <G> I see them hit flashes, they just aint taking metal with em!

XyZspineZyX
06-21-2003, 12:11 AM
tagert

353rd 357th and many other squads including chuck yegar used the strips with the tracers 50 cals came in strips with the tracers shipped like that Different types of .50 cal didnt use tracers try checking out

http://www.p51.mustangsmustangs.com/Books/index.shtml

and you will realize how many used the tracers and didnt have a choice

http://mysite.verizon.net/vze4jz7i/ls.gif

Good dogfighters bring ammo home, Great ones don't. (c) Leadspitter

XyZspineZyX
06-21-2003, 12:31 AM
LeadSpitter_ wrote:
- 353rd 357th and many other squads including chuck
- yegar used the strips with the tracers 50 cals came
- in strips with the tracers shipped like that
- Different types of .50 cal didnt use tracers try
- checking out and you will realize how many used
- the tracers and didnt have a choice

Hey nice link! But I didnt see the book Im got the info from. I dont know about how the ammo shipped, I know there were different types, and I dont know what the ground crew did or didnt do to remix it, but you have to realize that was a posability. One thing I do know, and that is what Capt Kit Carson of the 357th said about tracers in his book PURSUE & DESTROY, ie

Quote:
"Leave the 400 yard big deflection shots to the Holloywood movie producers, they'll have far more sucess with it than we ever could out here. your .50 caliber slugs have steel cores. WE DONT USE TRACER AMMUNITION. It gives a false illusion of distance and derection. But when the steel cores of your .50 caliber ammuntion hit the taget, the strike sparks, which appear as a winking lights, and your know you're scoring.
End Quote:

Tagert

XyZspineZyX
06-21-2003, 01:44 AM
It sounds like normal 50 cal shells non explosive or incidary just steel, did he say what plane it was for p51 b or c?

http://mysite.verizon.net/vze4jz7i/ls.gif

Good dogfighters bring ammo home, Great ones don't. (c) Leadspitter

XyZspineZyX
06-21-2003, 01:48 AM
http://www.cebudanderson.com/videos.htm

check out Bud WWII Guncamera Film (Currently must be viewed with Windows Media Player)

Tracers in his guncam video http://ubbxforums.ubi.com/infopop/emoticons/icon_biggrin.gif

must have been in the D i think the b and c didnt use the explosive incidary 50s

http://mysite.verizon.net/vze4jz7i/ls.gif

Good dogfighters bring ammo home, Great ones don't. (c) Leadspitter

XyZspineZyX
06-21-2003, 01:54 AM
LeadSpitter_ wrote:
- It sounds like normal 50 cal shells non explosive or
- incidary just steel,

Roger.

- did he say what plane it was for p51 b or c?

He didnt say... but in other sections he talks about what teh 357th had used, so I assume it is something they *learned* from doing.. thus i assume they used it on all versions.. and note he said *WE* not *I* as in all of the 357th didnt use tracers.

Tagert
PS Was there ever a "C" version used, other than for test?

XyZspineZyX
06-21-2003, 01:58 AM
did you download the video clip? It shows his actual guncam footage and theres tracers.

http://mysite.verizon.net/vze4jz7i/ls.gif

Good dogfighters bring ammo home, Great ones don't. (c) Leadspitter

XyZspineZyX
06-21-2003, 02:32 AM
LeadSpitter_ wrote:
- did you download the video clip? It shows his actual
- guncam footage and theres tracers.

Pretty cool! As for tracers, looks like someone didnt get the message to not use them! http://ubbxforums.ubi.com/infopop/emoticons/icon_wink.gif But seriosly, Im sure some personal choice played into the use of tracers or not. Mr. Carson being one of the highest scoring aces in the 357th makes me belive he had *some* understanding of it, but, hey, if you want to belive tracers where the norm, so be it. It defintaly makes for better and more interesting gun camera footage.. which may be on of the reaons those are the ones that get saved.

As for ammo types steel, incindary, ex, etc.. the mission usally dicatated that. In that the 357th usally did escort, the target was enmy AC, and it sounds like they used the steel core stuff, per Carson.. where as gnd attack of a fuel depo.. well, Im sure incdary would be loaded up.. I have a good book somewere that talks about all the ammo types, and the intended usesges.. but it must still be in the boxxes from my move.

Tagert

XyZspineZyX
06-21-2003, 04:12 AM
Don't get all drooling about the small amount of explosive material carried in .50 shells. 50 cals are 50 cals, and be it AP, API or HEI, it's nothing like a 20mm cannon nor should it expected to be.


From Tony Williams;

"If the fighter was to have all-round capability, i.e. effective against enemy bombers as well as fighters, then the first conclusion is that explosive/incendiary projectiles were essential. Comparisons between the destructive power of different types of rounds clearly reveal that the blast effect of HE, combined with the kinetic energy of the shell fragments being hurled through the target and the incendiary effect of the chemicals, add up to considerably greater effectiveness in most circumstances than can be achieved by the kinetic energy of solid bullets or AP projectiles.

This places a certain lower limit on the calibre of the gun. HEI projectiles were available in HMG (heavy machine gun: 12.7-15mm) and even RCMG (rifle calibre: 7.5-8mm) but these little bullets could contain only small quantities of chemicals. It was generally concluded that the smallest shell-firing calibre really worth bothering with was the 20mm cannon. This was demonstrated by the Luftwaffe, which much preferred the 20mm version of the MG 151 to the 15mm, despite the higher velocity (and therefore hit probability and armour penetration) of the smaller calibre, and the fact the HE and incendiary versions of the 15mm were available. The Soviet Air Force similarly showed an increasing preference for the 20mm ShVAK over the lighter and faster-firing 12.7mm Berezin.

Powerful HMGs like the Berezin and the .50" Browning were of course far from useless. They remained quite effective against fighters but would probably have found great difficulty in shooting down heavy bombers. The USN tested the 20mm Hispano against the .50", and concluded that the Hispano was three times as effective at normal fighting ranges, even though the gun weighed less than twice as much."



Two tracer shots ripping off a wing?

Preposterous.

-----------
Due to pressure from the moderators, the sig returns to..

"It's the machine, not the man." - Materialist, and proud of it!

Message Edited on 06/21/0312:16PM by kweassa

XyZspineZyX
06-21-2003, 06:32 AM
kweassa wrote:
- Don't get all drooling about the small amount of
- explosive material carried in .50 shells. 50 cals
- are 50 cals, and be it AP, API or HEI, it's nothing
- like a 20mm cannon nor should it expected to be.

No drooling here, but this is quote is a keeper! In that it highlights the basic differances between the USA designs and EVERYONE ELSES!

- From Tony Williams;

who is he, because I plan on using this quote in the future.

- "If the fighter was to have all-round capability,
- i.e. effective against enemy bombers as well as
- fighters,

STOP! That is it in a NUT SHELL! In the 40s every country in the world.. except the USA was within reach of a hostal countrys bomber. Hence the need for well rounded fighters, in that not only did they have to contend with fighters, but stop bombers. The USA had no real threat in the long range bomber dept, hence most of our fighters were design around the idea of going after other fighters. Except for the pacific, and as Tony noted, the NAVY dabbled with 20mm, but for the most part, most of our AC were design around the idea of gonig after other fighters. with that premis, lets continue.

- then the first conclusion is that
- explosive/incendiary projectiles were essential.
- Comparisons between the destructive power of
- different types of rounds clearly reveal that the
- blast effect of HE, combined with the kinetic energy
- of the shell fragments being hurled through the
- target and the incendiary effect of the chemicals,
- add up to considerably greater effectiveness in most
- circumstances than can be achieved by the kinetic
- energy of solid bullets or AP projectiles.

Which is what is needed to take out the likes of a B17.. but NOT a fighter! No need for a sledge hamer when a ball pean will do. You didnt have to blow a fighter to bits to take it out of the fight... which is what escorts are all about, that and once out, typically the damge was enough that gravity would take care of the rest, ie total distruction of the ac.

- This places a certain lower limit on the calibre of
- the gun.

For attacking bombers, and overkill for attacking fighters! Now Im sure someone is going to take a tanget on the overkill aspect.. and in these *GAMES* it is a nifty thing to see and do, but in war.. it didnt take much to damage a fighter enough to where it wasnt going to make it home... That *SIMPLE* aspect is miss by alot of people.. Im just gland the engineers of the USA in WWII didnt miss it.

- HEI projectiles were available in HMG
- (heavy machine gun: 12.7-15mm) and even RCMG (rifle
- calibre: 7.5-8mm) but these little bullets could
- contain only small quantities of chemicals. It was
- generally concluded that the smallest shell-firing
- calibre really worth bothering with was the 20mm
- cannon.

For bombers... but that little explosive would have a much bigger bang for its buck on a little figher.

- This was demonstrated by the Luftwaffe,

Who were particllary worried about BOMBERS.

- which much preferred the 20mm version of the MG 151
- to the 15mm, despite the higher velocity (and
- therefore hit probability and armour penetration)

But, higher velocity and higher hit probability is what is NECESSARY to take out a fast moving, fast jinking figher, as aposed to a level flying bomber trying to put it's eggs on target.

- of the smaller calibre, and the fact the HE and
- incendiary versions of the 15mm were available.

Makes sense, in that they had the well rounded figher, ie it had cannons, why even wory about the smaller HE stuff. But on a figher with only small arms, small HE might be a good thing againts other fighers... but even that is not necessary, in that as I mentiond before, just enough to take it out of the fight, let gravity do the rest!

- The Soviet Air Force similarly showed an increasing
- preference for the 20mm ShVAK over the lighter and
- faster-firing 12.7mm Berezin.

Who were particllary worried about BOMBERS.

- Powerful HMGs like the Berezin and the .50"
- Browning were of course far from useless. They
- remained quite effective against fighters but would
- probably have found great difficulty in shooting
- down heavy bombers.

True of the Lw bombers... but by the time we got there, they were not crossing over the pond.. thus again, not a concern. The IJN bombers were not as sturdy as the Lw stuff, thus the .50 was G2G aginst them bombers.

- The USN tested the 20mm Hispano
- against the .50", and concluded that the Hispano was
- three times as effective at normal fighting ranges,
- even though the gun weighed less than twice as
- much."

Weight it NOT the only concern, The SIZE WAS! In that you could have 6x0.50s on a F4u but only 4x20mm. Take the 3x effectivness and what do you have

3x0.50cal = 20mm

4x20mm vs 6x0.50

So four 20mm was like 12x0.50cals.. which makes it twice as *effective*... WHEN YOU GET A HIT!!! That is key!! A 20mm may be 3 times as effective when you get a HIT!! But due to the lower rate of fire, you hit probability goes DOWN.. Copule that withe FACT that you cant carry as many 20mm rounds as you can 0.50 cal rounds and it might all be a wash!

- Two tracer shots ripping off a wing?
-
-
- Preposterous.

Agreed, which is why *THEY* as in the 357th didnt use tracers, they loaed up with all steel core

Tagert


TAGERT
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If WAR was not the ANSWER.. Than what the H was your QUESTION?

XyZspineZyX
06-21-2003, 12:03 PM
And the most interesting part..

Why do the VVS MGs have those green nifty tracers ? They look like plasma bolts to my eye http://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif

I still stand that the LW should then have red bolts of the same size and type, so that we can see real Star Wars in the skies..

If the VVS tracers were altered to match LW ones, would the game become more balanced in any way ? Afterall, the LW tracers are much harder to 'trace' than the plasma bolts..

-Celorfie

XyZspineZyX
06-21-2003, 04:15 PM
Celorfie wrote:
- And the most interesting part..

Or most paranoid! <G>

- Why do the VVS MGs have those green nifty tracers ?
- They look like plasma bolts to my eye /i/smilies/16x16_smiley-happy.gif

They are pretty huge... but Im sure Oleg based them off of something.

- I still stand that the LW should then have red bolts
- of the same size and type, so that we can see real
- Star Wars in the skies..

LOL

- If the VVS tracers were altered to match LW ones,
- would the game become more balanced in any way ?

Actually that would make it unbalanced, in that it is balanced right now! <G>

- Afterall, the LW tracers are much harder to 'trace'
- than the plasma bolts..

Well.. Im certain they based the tracor color and size off of something... maybe they have some camera footage... I find it hard to belive *this* aspect/topic has not been addrssed in the past?


TAGERT
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If WAR was not the ANSWER.. Than what the H was your QUESTION?

XyZspineZyX
06-21-2003, 04:32 PM
"...as Tony noted, the NAVY dabbled with 20mm, but for the most part, most of our AC were design around the idea of gonig after other fighters..."

- Not necessarily.

As a quick historical reminder, by the time the battle of Stalingrad and Kursk was fought out, the major allies were already starting to discuss the fate of Germany after the war. Stalin continuously requests the US and UK to open up a second front. The need to switch a part of the air force to a keen tactical role - while maintaing the current scope of tactical attacks - was growing by the hour.

In short, by mid-1943, no other air force had more need for a fighter with a multi-role purpose role than the USAAF/USN. The fighter-bomber aspect of USAAF fighters, is something unseen in the RAF or the LW. Oh, they had their own share of "fighter-bombers", but the magnitude of the concept itself was very different.

USAAF fighters were DESIGNED for multi-purpose roles. They were USED as long-range escorts, which in their circumstances met the most successful results of them all. There's a fine line of difference there.

In short, the decision on part of the USAAF to retain the "50cal agenda", cannot be explained/justified by their actual use as the hunter-killer role. It's really a part of a very old debate - and the view I support is that the USAAF didn't particularly find anything wrong with .50s, and they just let the issue drift by. However, the turn of events in the 1950s, inevitably forced the US air force to rapidly abandon the "50cal agenda" and come to the conclusion which other countries reached years ago - the future of fighter armament was with cannons over 20mm.

....



"...Which is what is needed to take out the likes of a B17.. but NOT a fighter! No need for a sledge hamer when a ball pean will do. You didnt have to blow a fighter to bits to take it out of the fight... which is what escorts are all about, that and once out, typically the damge was enough that gravity would take care of the rest, ie total distruction of the ac."

- As I'll explain later, in a typical WW2 situation, the effectiveness of the single round which actually connects, was ultimately considered more important than the probability of the hit itself.

The RAF, who stopped worrying about German bombers since late 1942, never reverted to their 30 calibres, nor did they take 50 calibres. Instead, they went forward to perfecting the Hispano-Suiza cannons - which currently is considered probably the most effective(in sense of power AND accuracy) aircraft weapon ever in WW2.

....



"...For attacking bombers, and overkill for attacking fighters!..."

- There's no such thing as an "overkill" in air combat. Ultimately, there is only "effectiveness". The more powerful, the more effective. Only when the weapon is so considerably low in the performance of trajectory and velocity, it is not a viable option for a fighter armament.

.....



"Who were particllary worried about BOMBERS."

- The switch to MG151/20, occured way before the Allied bombing campaigns began. Wrong timeline.

.....



"So four 20mm was like 12x0.50cals.. which makes it twice as *effective*... WHEN YOU GET A HIT!!! That is key!! A 20mm may be 3 times as effective when you get a HIT!! But due to the lower rate of fire, you hit probability goes DOWN.. Copule that withe FACT that you cant carry as many 20mm rounds as you can 0.50 cal rounds and it might all be a wash!"

- The problem is, the average accuracy of A2A gunnery was so low in real life, that practically there wasn't a pronounced difference between HMGs and cannons.

In purely theoretical calculation, one might think increased numbers of lead poured into the air would increase the chance of hit rate to according levels.

The problem is, increasing the numbers of guns and ammo load with faster velocity to, let's say, double the amount?... did not necessarily result in 100% increase in the hit rate. It wasn't that linear.

There are many reasons for this:

1) increase in the number of guns also means increase in the overall recoil and vibrations of the platform itself, thus, the accuracy level never stays constant - R. Johnson states that the shock force of the eight machine guns firing at once, was enough to slow down a 400mph P-47 instantly by 5mph.

2) increasing the number of guns in a limited available space of an aircraft, inevitably results in mounting the guns inside the wings. Wing mounted weapons, are particularly sensitive to vibrations and instability, not to mention convergence. Problems with convergence was probably the largest hindering factor of the overall accuracy levels.

3) increased numbers of bullets flying through the air, via increased number of guns, means the increase in the hit probability was achieved through spreading apart the shots in a shotgun effect. The hits to the plane will be spread all over the target. Since HMGs, no matter how much their HE component, cannot ever be considered truly "High Explosive"(at least, compared to HE contents of either the German or British 20mm shells), spreading the shots to achieve hit probability, is ultimately futile.

An accurate shot where all of the HMG rounds fired concentrate on the point of target, is the only thing that will bring a plane down.

This is a significant logic, because it demonstrates the fact that "hit probability" means absolutely nothing by itself. No matter how many guns he has, ultimately, he'll need to concentrate well-aimed barrage of shots, as long as he is using machine guns. If he can do that, he might as well use a cannon to get three~four shots in. Which takes less time to bring down the fighter, and causes considerable damage no matter how much the hits are spread out - it will explode, and it will dig big holes on the surface.

4) The largest factor of them all, is the pilot skill. The grim truth of A2A gunnery in WWII, is that no matter what kind of weapon he uses, ultimately, the total effectiveness of his fired shots remains constant.

Rarely, does a pilot have enough time to spray a long stream of stable tracking shots towards a target. Even if you had a weapon with high velocity, and thus high hit probability, the overall weakness of the weapon demanded you put in a long burst of shots at a concentrated point - that required a chance, and a time, that often rarely existed in air combat. Most likely a pilot never gets more than one, two decisive chances to fire - the problem that bothered the pilot was whether he had enough firepower to do so.

This problem was quickly realized by most of the ace fighters of all countries - the preferences towards the 37mm cannons by Soviet Aces, was due to the fact that it can bring enemies down fast.

Likewise, Adolf Galland was partially unsatisfied with the new Bf109F models introduced in 1941. Galland specifically notes that the reduction of firepower to the MG151/15 15mm cannons, would effect the average pilots severely.


...


The bottom line?

If you're a pilot who gets in about 10 shots out of 100 fired by two guns, if you get double the ammo and guns, and fire 200 rounds with four guns, you'll still only get about 10 shots in.

Or, maybe you can get about 20 shots, by spreading them all over the target. But the overall effectiveness of those 20 shots, are about as equal as the 10 shots fired with two guns.

It's really funny if you look at it that way, but that's how A2A gunnery works. For the real life pilot, it's always a "wash" no matter what weapon he uses. So, the only real concern is, can you "wipe" someone out with that "wash" or not.

...

As for Mr. Tony Williams, check out his site at:

http://www.quarry.nildram.co.uk/

Aviation historian, and a frequent help to us sim gamers in need of critical info.


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Due to pressure from the moderators, the sig returns to..

"It's the machine, not the man." - Materialist, and proud of it!

XyZspineZyX
06-21-2003, 04:51 PM
Some more quotes from Mr. Williams.


"The American Browning .50 M2 is an undistinguished performer, particularly when compared with its closest competitor, the 12.7 mm Berezin. The relatively small incendiary content in the .50 API (0.9 g instead of 2 g) gives the Soviet round a flying start, which it adds to by its usefully higher rate of fire, then finishes off in style by being lighter as well, and thereby almost twice as efficient overall. The Browning also makes an interesting comparison with the Japanese Ho-5, which was basically the M2 slightly scaled up to take 20 mm cartridges.

It may appear that this low score of the .50 M2 is in disagreement with the satisfactory experience the USAAF had with this weapon. The answer to this apparent contradiction is that the .50 M2 proved very effective against fighters and (not too sturdy) bombers, if installed in sufficient numbers. Six or eight guns were specified as standard armament, resulting in a destructive power total of 360 or 480, at the cost of a rather high installed weight. Most American fighters were sufficiently powerful to have a high performance despite this weight penalty. Incidentally, the mediocre efficiency score of the .50 M2 is not only an effect of the low chemical content of its projectiles. Even if only the kinetic energy were considered, the efficiency of this gun would remain inferior to that of the UBS, B-20, ShVAK or Hispano, although better than that of the MK 108 or MG-FFM. To sum up, the preferred US armament fit was effective for its purpose, but not very efficient by comparison with cannon.

A further validation of the calculations is provided by the outcome of tests by the USN, which stated that the 20 mm Hispano was about three times as destructive as the .50 M2. In the above table, the ratio between their scores is 3.3.

The outstanding performer is clearly the German 30 mm MK 108, which achieves ten times the destructiveness of the .50 M2 for only twice the weight. It makes a particularly interesting comparison with the MK 103, which fired the same M-Geschoss projectiles. The MK 103 gains an advantage because of its higher velocity, but loses most of it due to its lower rate of fire, then is finally eclipsed in efficiency because of its much greater weight. No surprise that the Luftwaffe considered the MK 108 their premier air-fighting gun despite its low muzzle velocity. The Me 262 jet fighter, with four of these guns clustered in the nose, completely outclassed the firepower of every other WW2 fighter."



- Take special heed in this part:

"The answer to this apparent contradiction is that the .50 M2 proved very effective against fighters and (not too sturdy) bombers, if installed in sufficient numbers. Six or eight guns were specified as standard armament, resulting in a destructive power total of 360 or 480, at the cost of a rather high installed weight. Most American fighters were sufficiently powerful to have a high performance despite this weight penalty. "

In other words, the 6x.50s or 8x.50s load out was an absolute necessity, in order to cover for its not to inspiring efficiency. The combined weight of its weaponery, was a penalty that the plane had to overcome with sheer power - which explains part of the puzzle why the jug was never the maneuverable, or good climbing plane despite it's massive engine power.




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Due to pressure from the moderators, the sig returns to..

"It's the machine, not the man." - Materialist, and proud of it!

XyZspineZyX
06-21-2003, 06:27 PM
kweassa wrote:
- Not necessarily.

Within the context of what Williams said, ie "well rounded fighter" it was. Note his words not mine where his definition of well rounded was attacking bombers and fithers.

- As a quick historical reminder, by the time the
- battle of Stalingrad and Kursk was fought out, the
- major allies were already starting to discuss the
- fate of Germany after the war.

Ok.

- Stalin continuously
- requests the US and UK to open up a second front.
- The need to switch a part of the air force to a keen
- tactical role - while maintaing the current scope of
- tactical attacks - was growing by the hour.

True, and I agree that the definition of "well rounded" by Williams is not what I would call "well rounded". Well rounded is a *relitive* term. Our ground attack rolls came later, and you see that evelotion in the USA fighters hanging more and hevery ordance off of them.

- In short, by mid-1943, no other air force had more
- need for a fighter with a multi-role purpose role
- than the USAAF/USN.

now we are talking multi.. Williams was talking air to air, switching to air to gnd is a different topic, and does not change the *relitive* need... The USA from 41 to 45 had no real need for an aircraft to take out long range bombers that could hit the mainland. The bulk of our gnd attacks were performed by bombers, who were escorted by our fighters. The early type of surgical strikes were later performed by fighters with ord, once the ord was dropped, it was back to worring about fighters.

- The fighter-bomber aspect of USAAF fighters, is
- something unseen in the RAF or the LW. Oh, they
- had their own share of "fighter-bombers", but the
- magnitude of the concept itself was very different.

Agreed.. in that they were more worried about bombers then fighters.. The USA wasnt.

- USAAF fighters were DESIGNED for multi-purpose
- roles. They were USED as long-range escorts, which
- in their circumstances met the most successful
- results of them all. There's a fine line of
- difference there.

Agreed.. but fist and formost they were all designed as PERSUIT (fighters) aircraft, the multi purpose roll was something adapited to the allready designed fighters.

- In short, the decision on part of the USAAF to
- retain the "50cal agenda", cannot be
- explained/justified by their actual use as the
- hunter-killer role.

Huh? It is pretty simple, LOGISTICS is one big factor, one type of round shipped over in ships that was G2G for ground forces and aircraft, that along with the fact that what they were hunting-killing was other fighters.

- It's really a part of a very old
- debate - and the view I support is that the USAAF
- didn't particularly find anything wrong with .50s,
- and they just let the issue drift by.

Exactaly, there *was* nothing particularly wrong, if it aint broke, dont fix it!

- However, the turn of events in the 1950s,
- inevitably forced the US air force to rapidly
- abandon the "50cal agenda" and come to the
- conclusion which other countries reached years
- ago - the future of fighter armament
- was with cannons over 20mm.

DING! THANK YOU FOR MAKING MY POINT! As a quick historical reminder, by the 50s the USA was now comming within reach of long range bombers... Hence the need to take out long range bombers.

- As I'll explain later,

Could you point that out, because I didnt find it?

- in a typical WW2 situation, the effectiveness of
- the single round which actually connects, was
- ultimately considered more important than the
- probability of the hit itself.

Disagree.

- The RAF, who stopped worrying about German bombers
- since late 1942, never reverted to their 30
- calibres, nor did they take 50 calibres.

Because they NEVER stopped worrying about bombers.

- Instead, they went forward to perfecting the
- Hispano-Suiza cannons - which currently is
- considered probably the most effective(in
- sense of power AND accuracy) aircraft weapon
- ever in WW2.

In that it was the RAF's job to protect the UK.. not ours, which also explains why the most of the RAF aircraft did not evolve into the fighter bombers like ours did. It was not thier job.

- There's no such thing as an "overkill" in air combat.

Disagree 100%

-Ultimately, there is only "effectiveness".

And effectiveness is a *relitive* term.

-The more powerful, the more effective.

Disagree 100%.. Keep in mind, as I noted, the role of an escort is to keep the fighters off of the bombers.. you dont have to blow it up into 1000 chunks to take it out of the fight.. and it does not take many hits from a 50 cal to take you out of the fight.. gravity will do the rest. That simple realisation on the part of the USA early on saved our A. To the point that early on it was mandated not to peruse the enmy fighters once they broke off, stay with the bombers. Not until we had considerbale advantges did they allow our fighters to persue their fighters that had disingauged.


- Only when the weapon is so considerably low
- in the performance of trajectory and velocity,
- it is not a viable option for a fighter armament.

Agreed.

- The switch to MG151/20, occured way before
- the Allied bombing campaigns began. Wrong timeline.

DING! In that Germany was allways concerned with bombers, even in spain.

- The problem is, the average accuracy of A2A
- gunnery was so low in real life, that practically
- there wasn't a pronounced difference between HMGs
- and cannons.

Huh? the fact that accuracy was so bad would motivate you to get more lead out there in a bigger patern!!

- In purely theoretical calculation, one might think
- increased numbers of lead poured into the air would
- increase the chance of hit rate to according levels.

Purely Theoretical! LOL! You cant discount it that easly!

- The problem is, increasing the numbers of guns and
- ammo load with faster velocity to, let's say, double
- the amount?... did not necessarily result in 100%
- increase in the hit rate. It wasn't that linear.

Agreed.

- There are many reasons for this:
-
-
- 1) increase in the number of guns also means
- increase in the overall recoil and vibrations of the
- platform itself, thus, the accuracy level never
- stays constant -

Accuracy.. but the vibration would actualy add to the shot gun effect and give you a nice spread.


- R. Johnson states that the shock
- force of the eight machine guns firing at once, was
- enough to slow down a 400mph P-47 instantly by 5mph.

Huh, because Mr. Carson.. one of the higest scoring aces in the 357th said:

quote

"Incidentally, firing the guns did not noticebly slow the airplane down; the velocity loss was less than one mile per hr. What the pilot felt was the vibration of the six guns recoling. When worked out, a P51 weighing 9,000 lbs. and going 300mph. (440ft. per secon) has a kinetic energy of 27 million ft. pounds. That of all six guns firing simultaneously (actually the dont; the fire at random with respect to each other, but for our purposes let's lump thier kinetic energy together) is about 75 thousand pounds. Thus the speed differentiation is negligible."

end quote

Now Im sure that you will agree the P47 was heavier, and that the same kind of numbers would account for the extra two MGs.


- 2) increasing the number of guns in a limited
- available space of an aircraft, inevitably results
- in mounting the guns inside the wings. Wing mounted
- weapons, are particularly sensitive to vibrations
- and instability, not to mention convergence.

True, but it would also be true for 20mm cannons in the wings. So it is a wash.

- Problems with convergence was probably the largest
- hindering factor of the overall accuracy levels.

Agreed.. but also true for 20mm in the wings.

- 3) increased numbers of bullets flying through the
- air, via increased number of guns, means the
- increase in the hit probability was achieved through
- spreading apart the shots in a shotgun effect.

Agreed 100%. And when you consider the fact that it does not take as much to dmg a fighter as it does a bomber it shold be clear that when your trying to TRACK a fast MOVING, fast TURNING fighter a good SPREAD is a good thing... Which is just the OPPOSITE when you TACK a slow MOVING, slow TURNING bomber a good FOCUS is a good thing.

- The hits to the plane will be spread all over the
- target.

EXACTALLY! And on a figther that is a good thing. Not only do you increase the chance of a hit with a SPREAD, but you are more lilky to hit several different systems in the small fighter.. from that point on.. let gravity do the rest.


- Since HMGs, no matter how much their HE
- component, cannot ever be considered truly "High
- Explosive"(at least, compared to HE contents of
- either the German or British 20mm shells), spreading
- the shots to achieve hit probability, is ultimately
- futile.

On a slow moving bomber.. I agree, on a fast moving figher I disagree.

- An accurate shot where all of the HMG rounds fired
- concentrate on the point of target, is the only
- thing that will bring a plane down.

LOL! Well someone better get a time machine and go back and tell all them US aces that they didnt shoot down all them planes! P L E A S E!


- This is a significant logic,

Is that what the kids are calling it? Sounds like you want to ignor history?

- because it demonstrates the fact that "hit
- probability" means absolutely nothing by itself.

Never said by itself! There is a limit!

- No matter how many guns he has, ultimately,
- he'll need to concentrate well-aimed barrage
- of shots, as long as he is using machine guns.

Nope!

- If he can do that, he might as well
- use a cannon to get three~four shots in.

If.. but that aint the case.

- Which takes less time to bring down the fighter,
- and causes considerable damage no matter how
- much the hits are spread out - it will explode,
- and it will dig big holes on the surface.

I guess we will have to agree to disagree than.

- 4) The largest factor of them all, is the pilot
- skill. The grim truth of A2A gunnery in WWII, is
- that no matter what kind of weapon he uses,
- ultimately, the total effectiveness of his fired
- shots remains constant.

remains a constant? I doubt it, Im sure his skill improved with time on the job.

- Rarely, does a pilot have enough time to spray a
- long stream of stable tracking shots towards a
- target.

Not ture.. maybe in some games.. but check out some of the old gun footage, plenty of them show long bursts... So I dont know where you get or base the rarely statment.

- Even if you had a weapon with high velocity,
- and thus high hit probability, the overall weakness
- of the weapon demanded you put in a long burst of
- shots at a concentrated point -

Nope! Just enough to take em out of the fight, you dont have to blow them to bits.. gravity and the sudden stop on mother earth will take care of that.

- that required a chance, and a time, that often
- rarely existed in air combat.

rarely.. based on? I think you are confusing *games* with history? For the most part, most a2a kills were a situation where the guy who got shot down NEVER SAW THE GUY WHO SHOT HIM DOWN!! That is to say the NORM in flight sims is the DOGFIGHT where two guys go at it for min at a time, in reality MOST a2a kills were BLIND SIDED KILLs where the guy didnt know what hit him. Hence, the attacker had a nice line up and long burst put in him before the attackie ever moved.

- Most likely a pilot never gets more than
- one, two decisive chances to fire - the problem that
- bothered the pilot was whether he had enough
- firepower to do so.

Disagree.


- This problem was quickly realized by most of the
- ace fighters of all countries - the preferences
- towards the 37mm cannons by Soviet Aces, was due to
- the fact that it can bring enemies down fast.

Actually they liked it for gnd attack, not a2a, and ALL of them had the fear of BOMBERS haning over their heads (pun intended) hense everyone but us focus on cannons, we just dabbled in them.


- Likewise, Adolf Galland was partially unsatisfied
- with the new Bf109F models introduced in 1941.
- Galland specifically notes that the reduction of
- firepower to the MG151/15 15mm cannons, would effect
- the average pilots severely.

BOMBERS!

- The bottom line?
-
- If you're a pilot who gets in about 10 shots out of
- 100 fired by two guns, if you get double the ammo
- and guns, and fire 200 rounds with four guns, you'll
- still only get about 10 shots in.

Disagree 100%

- Or, maybe you can get about 20 shots, by spreading
- them all over the target. But the overall
- effectiveness of those 20 shots, are about as equal
- as the 10 shots fired with two guns.

Disagree 100%

- It's really funny if you look at it that way, but
- that's how A2A gunnery works. For the real life
- pilot, it's always a "wash" no matter what weapon he
- uses. So, the only real concern is, can you "wipe"
- someone out with that "wash" or not.

Nope.

- As for Mr. Tony Williams, check out his site at:

Hey Thanks!

- Aviation historian, and a frequent help to us sim
- gamers in need of critical info.

Another source is allways good.




TAGERT
-------------------------------------------------------------------------------------------------------
If WAR was not the ANSWER.. Than what the H was your QUESTION?

XyZspineZyX
06-21-2003, 09:17 PM
Try telling the people who actually research these things to make a living, that a spread out shot with a weapon under the property of 20mm HE content, means something.

0.2g of HEI content, again, is nothing like what you would expect with a 20mm HE shell. Spread the shots here and there, and expect the enemy plane to go down? With a belt which usually the most important of shells are AP and API content?

Dream on, dude.







-----------
Due to pressure from the moderators, the sig returns to..

"It's the machine, not the man." - Materialist, and proud of it!

XyZspineZyX
06-21-2003, 10:51 PM
kweassa wrote:
-
- Try telling the people who actually research these
- things to make a living, that a spread out shot with
- a weapon under the property of 20mm HE content,
- means something.

No, no telling them anything! In that most of those arm chair quarterbacks have their minds made up. Take Williams web sight for example.. He want to consider the fancyful *WHAT IF* where a Im more concerned with what was.. You can tell me over and over that the only way to take down a airplane is with a 20mm HE shell... Where you use William as a reference... Ill stick with facts that many AC in WWII were shot down with the likes of 0.50 cals, and Ill stick with the reference over the people that did the job over some guy who starts of with a fancyful *WHAT IF*. Dont take it personal, it's just me and my opinion!

- 0.2g of HEI content, again, is nothing like what
- you would expect with a 20mm HE shell. Spread the
- shots here and there, and expect the enemy plane to
- go down?
- With a belt which usually the most
- important of shells are AP and API content?

Try and twist it around.. but all Im saying is back in the days when... As William even admits, the computed leadning gun sight was a raraty an the old eye ball and brain did all the work, one had to offset that fact with a higher probablity of hitting the target, and you get that with more guns and a good spread... Once you admit to yourself that a fighter is easier to take down than a bomber with regards to the round size.

- Dream on, dude.

No need to DREAM.. I have HISTORY on my side.




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XyZspineZyX
06-22-2003, 04:32 AM
The Brownings were PLENTY powerful in real life. There were stories of several Browning rounds blowing through trucks like they were paper and actually piercing Tiger tank armor by bouncing under to the weak spots. I think they could have tighter shot groupings on the Jug and have the recoil lessened (come on, the plane is frikin heavy!)

<img src=http://img.villagephotos.com/p/2003-6/219643/GCS0705copy.JPG>

<center><table style="filter:glow[color=black,strength=3)"> Warning: My intense sense of humor may tug at the stick crammed in your shaded spot. If you treasure your lack of humor please refrain from reading my posts as they may cause laughter.</table style></center>



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The_Blue_Devil
06-22-2003, 05:15 AM
Catseye_333rd wrote:
- There is very little convergence in FB P47.
-
- Do some tests and compare convergence on other wing
- mounted armament at the same range and you can see
- the P47 spray all over the place. Lucky if you can
- get one bullet to hit home.
-
Switch to night time, leave your Jug parked..You will clearly see the bullets cross at the convergence distance


<center>----------------------------------------------------------------------------</center>
<center>[b]"Pilots who liked to dogifght could do it their own way. I avoided it. I always attacked at full speed and I evaded a bounce in the same manner. When you were hit from above and behind, and your attacker held his fire until he was really close, you knew you were in with someone who had a great deal of experience.-Erich Hartmann"[b]</center>

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XyZspineZyX
06-22-2003, 05:16 AM
In the jet age, engagement ranges opened up and 20mm shells carry farther. The faster you are moving, the higher the drag on your projectiles and again the heavy rounds are choice.

I like the part about how having a mass of rounds doesn't make much difference and then in the next post Mr. Williams is quoted as saying ROF is important (Mk108 vs 103 at one point).

Range matters, and for WWII fighters vs fighters the .50 could handle the ranges neccessary. The big reason to have 20mm then to attack bombers was to be able to fire from beyond the range of the defensive guns and get good hits.

Did Mr. Williams have anything to say about dependability? Some factors seem to have been forgotten. I'd rather listen to the people who make and fly the real thing for a living than someone who sells stories about it later on. Not to say the guy is a turd, but I do believe that weapons choices were not taken lightly by the Air Force... those guys lived and died up there, it's not like ordering Girl Scout cookies!


Neal

XyZspineZyX
06-22-2003, 06:38 AM
WWMaxGunz wrote:
- In the jet age, engagement ranges opened up and 20mm
- shells carry farther. The faster you are moving,
- the higher the drag on your projectiles and again
- the heavy rounds are choice.

That, and another factor is the computing sights improved, thus, you didnt needs to account for the pilots lack of aim by with more guns to improve his chance of hit percentage.

- I like the part about how having a mass of rounds
- doesn't make much difference and then in the next
- post Mr. Williams is quoted as saying ROF is
- important (Mk108 vs 103 at one point).

I noticed a few contrdictions in his storys too.. All good info his presents, I just dont agree with his interptation on some.. well most of it. Espically in that one part.. the what if section about picking the best this and that to make a well rounded figher.. Ill bet the guys back in WWII wish they too could ingor all the REAL LIFE sitiatins that drove alot of the decision, logistic, etc..

- Range matters, and for WWII fighters vs fighters the
- .50 could handle the ranges neccessary.

Range and distruction power.. It dont take much! One thing I dont *think* IL2 if any sim models is the STRESS FATIGUE that ocurs do to damage.. for example, a hit threw a cross memeber on an AC might not case the wing to fold up and off at 100mph.. but at 300mph the added force on it could. I have fired 0.50 cals.. I have seen what they can do to steel.. I know they can punch threw aluminm and the frame underneath and any other systems in the way. And it it was not enough to dmg the AC enough to cause it to crack up later.. it surely was enough to wake the pilot up and cause him to break off his attack on the bombers and head for home.


- The big reason to have 20mm then to attack bombers
- was to be able to fire from beyond the range of the
- defensive guns and get good hits.

That too!

- Did Mr. Williams have anything to say about
- dependability?

I did see somthing in there about it on his fancyful wish list section.

- Some factors seem to have been forgotten.

That is the neat thing about writing on something 60 years later... not too many of the guys left around to argue with you about it.

- I'd rather listen to the people who make
- and fly the real thing for a living than someone who
- sells stories about it later on.

EXACTALLY! But even those have to be taken in contex! It is hard to sift threw some of the storys.. the tril of the fight can taint a story. /i/smilies/16x16_smiley-wink.gif That is why I like reading Mr. Carsons book... he became an aero engineer after the war, and with that knowlege went back and look at what he experanced with an engineers eye.. it is very interesting and seems to be just a little biased! /i/smilies/16x16_smiley-wink.gif

- Not to say the guy is a turd, but I do believe
- that weapons choices were not taken lightly by
- the Air Force... those guys lived and died up
- there, it's not like ordering Girl Scout cookies!

Exactally!



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XyZspineZyX
06-22-2003, 06:42 AM
Hittson wrote:
- The Brownings were PLENTY powerful in real life.

Powerful, Dependable, Great ROF, Not too big, Not too small, just right for attacking fighers and light armor.

- There were stories of several Browning rounds
- blowing through trucks like they were paper

More than a few! Ive done it! Hell, my 98K 8mm rifle will terr threw 1/4" steel!

- and actually piercing Tiger tank armor by bouncing
- under to the weak spots.

Wow.. never head that one! Cool!

- I think they could have tighter
- shot groupings on the Jug and have the recoil
- lessened (come on, the plane is frikin heavy!)

Yeah, the recoil is way over modled



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XyZspineZyX
06-22-2003, 05:37 PM
Hittson wrote:
- and have the recoil lessened (come on, the
- plane is frikin heavy!)

On that subject, here is what COL Leonard Kit Carson, one of the highest scoring aces in the 357th, and became an aero engineer after the war had to say about the P51.. A much lighter plane, with regards to recoil and the loss of speed

quote

"Incidentally, firing the guns did not noticebly slow the airplane down; the velocity loss was less than one mile per hr. What the pilot felt was the vibration of the six guns recoling. When worked out, a P51 weighing 9,000 lbs. and going 300mph. (440ft. per secon) has a kinetic energy of 27 million ft. pounds. That of all six guns firing simultaneously (actually the dont; the fire at random with respect to each other, but for our purposes let's lump thier kinetic energy together) is about 75 thousand pounds. Thus the speed differentiation is negligible."

end quote


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XyZspineZyX
06-22-2003, 08:32 PM
That little foot pounds comparison is somewhat weak in that it involves instant measures where over time the recoil adds up.

There's that other account of the P47 losing 5mph instantly that is even farther off since a 2 second burst at that rate should about stall the plane.

Any proper treatment of the situation would involve time and include the planes thrust. It would also go over most peoples heads as it would involve integrals. If there was data from chart recorders though, we could all get into that.


Neal

XyZspineZyX
06-22-2003, 10:20 PM
WWMaxGunz wrote:
- That little foot pounds comparison is somewhat weak

True, but the as you noted, anything more would have been over most peoples heads. At least he assumed the worst case, where all firing at once, which still didnt result to squat!

Anther way to look at it, 27*10^6/75*10^3=360

Thus with all guns firing at once, the kinetic energy of the guns is only only negates 1/360 of the kinetic energy of the whole system.

- in that it involves instant measures where over time
- the recoil adds up.

Hmmm.. would it? There are four forces on an AC.. Thrust, Drag, Gravity, Lift.. Basically, assuming a constant with all guns firing at once, like Carson did.. that would just subtract from the Thrust, much like Drag does... You would have to have a long long burst (time) before you made a dent in that 1/360th

- There's that other account of the P47 losing 5mph
- instantly that is even farther off since a 2 second
- burst at that rate should about stall the plane.

True! And that is why alot of these pilots accounts have to be takin within the context of the statment.. He probally meant that post frining he typically noticed his speed had reduced... Im sure that the manuvering of the plane to keep the bullets on target had more to do with the speed reduction then the guns firing.. Which is what Carson was getting at.. The guns dont really effect it

- Any proper treatment of the situation would involve
- time and include the planes thrust.

Agreed. And it looks like it would just contribute to the equation like drag does, subtracting from thrust.

- It would also go over most peoples heads as
- it would involve integrals.

True.

- If there was data from chart recorders
- though, we could all get into that.

I think we have all we need.. actually just do the one axis, thrust and drag.. Using kinetic energy makes it much easier, and get right to the point.. which is why Carson probally went with it.. Getting the Thrust of a P47.. could get that from eng info.. And Im sure the drag coeficent is out there soemwhere.. but it is so much easier to just do the mass and speed! <G>



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XyZspineZyX
06-23-2003, 10:44 AM
That bouncing-bullets-penetrate-underside-of-tanks has been rejected to the realms of bogus by simple calculations in this forum some weeks before....sorry.

In general the p-47's armament has shown to be very effective on fighters...

XyZspineZyX
06-25-2003, 02:15 AM
muffinstomp wrote:
- That bouncing-bullets-penetrate-underside-of-tanks
- has been rejected to the realms of bogus by simple
- calculations in this forum some weeks
- before

Ill start off with what I know to be true.. A 0.50 cal will tear threw some pretty thick metal.. how thick depends on alot of things.. But when I fired a 50 call were were shooting at some old armored vehicals.. old APC and it went threw them like butter. What I dont know is how thick the steel was on the bottom and top of a TIGER tanks, but I do know that in general all tanks have thinner tops and bottoms.

With that said, check out this link

http://www.vectorsite.net/avp47.html#m6

Paragraph two, where it notes that 50 cals were found to go threw tops and bottoms of TIGER tanks.. Granted, one would think that most of the enery would be absorbed in the inital gnd strike, to where it couldnt make it threw the bottom of the tank.. But WAR is a funny place, and funny things happen. With out too much effort I can imagine a TIGER tank cresting a small hill, and a P47 comming at it head on low and fast, the bullets wouldnt strike the gnd as much as deflect off of it and into the belly of the tank. Im sure if that happend it was not the norm.. but it is one example, Im sure there are more.

So, now, you have to ask yourself.. do I belive a bunch of calculator jockies talking about it in a forum 60 years ago, or personal accounts of the guys who were actully there and wrote about it... Personally, I dont put too much weight on the forum guys! /i/smilies/16x16_smiley-wink.gif

-...sorry.

Dont be, it is not the fist time a bunch of guys in a fourm were wrong! /i/smilies/16x16_smiley-wink.gif

- In general the p-47's armament has shown to be very
- effective on fighters...

In real life, yes, that is true



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XyZspineZyX
06-25-2003, 03:58 AM
The M-2 Browning .50 cal was designed to kill tanks in WW1. It is of larger calibur, and low muzzle velocity. During head on attacked your rounds have enough weight to bust concrete, but from the air chase the rounds lose to much velocity to kill.'
In a chase get close, so close you can se what kind of hair cut he has, then bust his ***.

ick

http://www.roush.org/rausch1.gif

XyZspineZyX
06-25-2003, 04:18 AM
icaris1 wrote:
- The M-2 Browning .50 cal was designed to kill tanks
- in WW1.

Huh.. I thought the 30cal was a WWI project, and that the 50 came out between the wars? Im no expert on that timeline, just something I was under the impression of.

- It is of larger calibur, and low muzzle
- velocity.

That is a relitive statment.. with that said, reletive to what?

- During head on attacked your rounds have
- enough weight to bust concrete,

Well I never did a headon attack of a block of concrete... So Ill have to take your word for it! <G> But I have pop a few rounds off into a steel truck and APC... like butter!

- but from the air chase the rounds lose to much
- velocity to kill.'

NEGATIVE GHOST RIDER! Now it has been awhile sence my last physics class, let alone the last time I used it, so bare with me.. But didnt Ol Einstine say something about relitive velocitys? Now for the most part I think it would be safe to assume that the drag on the bullet is a constant.. in that it's shape is not changing.. that and the world gravity can be assumed to be a constant.. With that said, why do you think a bullet would loose more velocity when fired from an air platform moving at 300mph than a stanory gnd gun (ie 0mph). The relitive velocity of the bullet would still be the same.. Would it not? If not, then there has to be something in the drag eq for the bullet that is chaning (ie not a or same constant).. but for the life of me I cant imagine what it would be.

- In a chase get close, so close you can se what
- kind of hair cut he has, then bust his ***.

Close is allways better... for just about everything if life... Except BBQ's dont get too close!



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XyZspineZyX
06-25-2003, 05:02 AM
MOH_TRACKER wrote:
- too weak?? lmao those guns are some of the toughest
- i've seen

I wouldnt go that far. They do alright, but they dont hit nearly as hard as most FW190s or anything packing an mk108. 3x20mm on the La7 is better too.

<center>http://smack.telecom.ksu.edu/il2/images/trackwerks400.jpg (http://smack.telecom.ksu.edu/il2/)</center>

XyZspineZyX
06-25-2003, 05:38 AM
Salute

Both Kweassa and MaxGunz are missing something.

The velocity of the .50 cal is better than that of the 151/20 or Mk 108 and the higher velocity means the .50 cal is much more accurate. This is especially the case when compared to the Mk 108.

Gunz is wrong in suggesting the 20mm rounds of the 151/20 carry further. The greater velocity of the .50 cal will carry it further.

The 151/20 and Mk 108 were good weapons for taking down slow maneuvering targets like B-17's, but their ability to hit a fast moving fighter is considerably less than a .50 calibre.

Tony Williams points this out in his Article, something which the German side seems to have passed over.

The most important thing to understand is that the USAAF weapons were, like the German, designed to fill a need. The Germans needed very heavy weapons to take down 4 engined bombers with robust structures. On the other hand, the USAAF's heaviest targets were twin engined bombers, (with the odd 4 engined Me323) and for this, the massed .50 calibres were more than sufficient.

Read the combat reports. Time after time, the reports of encounters between USAAF fighters and German or Japanese twin engined bombers, recount how a few bursts from the .50 calibres were enough to do serious structural damage to the bombers.


Cheers RAF74 Buzzsaw

XyZspineZyX
06-25-2003, 06:23 AM
RAF74Buzzsaw_XO wrote:
- Salute
-
- Both Kweassa and MaxGunz are missing something.
-
- The velocity of the .50 cal is better than that of
- the 151/20 or Mk 108 and the higher velocity means
- the .50 cal is much more accurate. This is
- especially the case when compared to the Mk 108.

Well.. I dont know how the higher velocity translates into more accurate, cept that with a higher initial velocity, and thus velocity it should fly a littl straighter? I mean gravity is a constant, it acts on large or small mass bullets with the same force... but drag is typically going to be larger for larger, thus typically blunter rounds.. but the gun sight, or at least the pilot would take into account the faster drop for larger slower rounds.. so.. I still dont see how higher velocity is more accurate, cept for a semi good/bad aim.. ie a pilot or sight that does not do a good job of estimating the drop.. he would probally have better luck with a straight flying 50.. Someting ait right here.. I think Im forgeting a physics thing?

- Gunz is wrong in suggesting the 20mm rounds of the
- 151/20 carry further. The greater velocity of the
- .50 cal will carry it further.

Emmmmm not sure... but one thing I am sure about, ANY round that you increase the velocity on increases the kenitic energy by a SQUARED factor... That is

Ek = (1/2)mv^2

Where:
Ek = Kinetic Energy
v = velocity
m = mass

I dont have any real numbers, but, just as an example lets saw we have two rounds..

CASE 1 (double the speed)
Round One
m1 = 10
v1 = 800

Round Two (TWICE as Fast as Round One)
m2 = 10
v2 = 1600

The Kinetic Energy for Round One is:

Ek = 0.5*10*(800)^2 = 3200000

The Kinetic Energy for Round Two is:

Ek = 0.5*10*(1600)^2 = 12800000

12800000/3200000 = 4

Thus TWICE the speed gives you FOUR times the Kinetic Energy

CASE 2 (double the size)

The Kinetic Energy for Round One is:

Ek = 0.5*10*(800)^2 = 3200000

The Kinetic Energy for Round Two is:

Ek = 0.5*20*(800)^2 = 6400000

6400000/3200000 = 2

Thust TWICE the size gives you TWICE the Kinetic Energy

Summary, the SPEED of the bullet is much more important than the size with regards to damage caused by Kinetic Energy. Note for all you HE folks out there, this is a comparsion of solid steel rounds.. HE stuff is a little more complicated, and due to that complication it makes them a little less dependable too! Fuse this, timmer that, etc!


- The 151/20 and Mk 108 were good weapons for taking
- down slow maneuvering targets like B-17's, but their
- ability to hit a fast moving fighter is considerably
- less than a .50 calibre.

EXACTALLY!!!!!! A poit I have been laboring to make here! Take, along with the fact that you can also fit more of the 50 within the confines of an aircraft and you also improve your proballity of a hit! NOTE by confines I mean you didnt have to add gun pods which induce more drag on the AC and thus lower it's perfomrance... Which is not a big deal when hunting B17s but get jumped by a P51 and youll probally whish you could dump them pods.

- Tony Williams points this out in his Article,
- something which the German side seems to have passed
- over.

BUZZSAW!!! Can you give me the link to that Articale, or the ISBN number of the book your refering too! I could make good use of that info in future topics!!

- The most important thing to understand is that the
- USAAF weapons were, like the German, designed to
- fill a need. The Germans needed very heavy weapons
- to take down 4 engined bombers with robust
- structures. On the other hand, the USAAF's heaviest
- targets were twin engined bombers, (with the odd 4
- engined Me323) and for this, the massed .50 calibres
- were more than sufficient.

DING! GIVE THIS MAN A CIGAR!!! EXACTALLY!!!

- Read the combat reports. Time after time, the
- reports of encounters between USAAF fighters and
- German or Japanese twin engined bombers, recount how
- a few bursts from the .50 calibres were enough to do
- serious structural damage to the bombers.

COOL! Got any links?



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XyZspineZyX
06-25-2003, 06:38 AM
tagert wrote:
- Someting ait right here.. I think Im forgeting
- a physics thing?

Yes you bone head!

F=ma

Gravity is constant, but, is not a force, gravity and mass is! DOH! <G> Thus bigger bullet, bigger downward force, biger drop.. DUH!





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XyZspineZyX
06-25-2003, 06:44 AM
tagert wrote:
- F=ma
-
- Gravity is constant, but, is not a force, gravity
- and mass is! DOH! <G> Thus bigger bullet, bigger
- downward force, biger drop.. DUH!

Yet.. a feather and a block of iron will fall at the same rate in a vacume... thus, drag plays into this big time! Thus that force has to be takin into account along with this

PS I usally dont talk to myself, but, sometimes Im the only one making any sense! <G>




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XyZspineZyX
06-25-2003, 09:50 AM
Two bullets fired at equal speed and having same drag but of different mass will not fall at same time.You need to use wolfstriked's law that states an object in motion tends to stay in motion/i/smilies/16x16_smiley-happy.gif

Reason why such a heavy plane as the P47 was outstanding in zoom climbs but cant sustain climb for poop.

XyZspineZyX
06-25-2003, 11:00 AM
Guys, i really dont see where your problem ist. Get behind a bomber in QMB and fire away in a P47. Or strafe a convoy.

those 50ies are devastating.

If you have problems shooting down fighters, it´s really about aimung and dispersion. Last time i clipped a wing of another 47 with just a second long burst.

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XyZspineZyX
06-25-2003, 01:27 PM
RAF74Buzzsaw_XO wrote:
- Salute
-
- Both Kweassa and MaxGunz are missing something.
-
- The velocity of the .50 cal is better than that of
- the 151/20 or Mk 108 and the higher velocity means
- the .50 cal is much more accurate. This is
- especially the case when compared to the Mk 108.
-
- Gunz is wrong in suggesting the 20mm rounds of the
- 151/20 carry further. The greater velocity of the
- .50 cal will carry it further.

Negative.
Max did not specify the 151/20, only the reason that 20mm guns were moved up to in general.

The lighter the projectile, the quicker it loses speed and this is much more true above the speed of sound. Frontal surface has some effect however you should note that equivalent density projectiles of different calibres scale up in 3 dimensions while frontal area scales up in 2.

Since at supersonic speeds the excess speed bleeds off pretty quickly, a heavier projectile with proportionatly less frontal area that starts out slower can still be moving faster out to even moderate ranges for the heavier weapon. Don't believe it? Compare ranges and impacts between an M16, an M14, and an M2. Which has the higher muzzle velocity? Which has the higher effective range?

Just because you can pull a not so great 20mm out from the pile doesn't mean that 20mm guns are all less. look at the Hispano-Suiza.

The bigger =equivalent= projectile has more carry.

You're talking about a bullet that has 42% of the weight of the shell and a Muzzle Velocity a whole 22% higher. How about you post some ballistics tables on those rounds, huh? The only tables I have are for rifle and pistol cartridges but they do point out some interesting comparisons including relative sizes and drag. Weight is a bigger factor when it comes to speed loss.


Browning .50
// APIT - AP - HE - AP

APIT
mass = 0.0485
speed = 870.0
power = 0.002

AP
mass = 0.0485
speed = 870.0
power = 0

HE
mass = 0.0485
speed = 870.0
power = 0.00148


Hispano-Suiza Mk.I
// HET - AP - HE - AP

HE/HET
mass = 0.129
speed = 860.0
power = 0.012

AP
mass = 0.124
speed = 860.0
power = 0

MG 151/20
// APIT - HE - HE - MG - MG
APIT
mass = 0.115
speed = 710.0
power = 0.0036

HE
mass = 0.115
speed = 705.0
power = 0.0044

MG
mass = 0.092
speed = 775.0
power = 0.0186

MG/FF
// APIT - HE - HE - MG

APIT
mass = 0.115
speed = 580.0
power = 0.0036

HE
mass = 0.115
speed = 585.0
power = 0.0044

MG
mass = 0.092
speed = 690.0
power = 0.0186

ShVAK
// APIT - HE

APIT
mass = 0.096
speed = 800.0
power = 0.001

HE
mass = 0.0676
speed = 800.0
power = 0.0068


Perhaps you could answer which AA guns tend to have the longer range, .50's or 20mm's?

- The 151/20 and Mk 108 were good weapons for taking
- down slow maneuvering targets like B-17's, but their
- ability to hit a fast moving fighter is considerably
- less than a .50 calibre.

I think you're thinking of the 151/FF which had a very low velocity compared to the 151/20, but a much higher rate of fire just like the 108 compared to the 103.

- Tony Williams points this out in his Article,
- something which the German side seems to have passed
- over.

German side? Would you be talking about some people who post here? Is it time for Conspiracy Hats yet?

- The most important thing to understand is that the
- USAAF weapons were, like the German, designed to
- fill a need. The Germans needed very heavy weapons
- to take down 4 engined bombers with robust
- structures. On the other hand, the USAAF's heaviest
- targets were twin engined bombers, (with the odd 4
- engined Me323) and for this, the massed .50 calibres
- were more than sufficient.

That covers the flying targets. I do agree that for WWII speeds and ranges that the M2 was a good choice when using 4 or more at once.

As far as taking out tanks noted here. Top armor is thinner and it is also not all covering. The armor over the engine on many tanks had slots in it to vent air. It is weaker just for not being solid even when rounds would strike the armor there. I see one site listing the VIE top armor at 25mm and the VIB top armor at 40mm. Floor armor for the E model shows as 25mm while for the B it shows 40mm at the front and 25mm at the rear.

What kind of APC were you firing at Tagert? If it was an M113 then you should know that the armor is hardened aluminum. In any case, I don't think I've heard of an APC with an inch of hardened steel except for maybe the Ram and Kangaroo carriers used by the Brits in WWII, those were tanks with the turrets taken off and some mod to carry troops inside.

A 50 cal fired from high in the air is going to lose more velocity from drag than it will gain from gravity. Gravity adds about 10m per second per second. The round has to travel an entire second to pick up 10m/second extra speed and the round will lose a lot more than that due to drag in that amount of time.

- Read the combat reports. Time after time, the
- reports of encounters between USAAF fighters and
- German or Japanese twin engined bombers, recount how
- a few bursts from the .50 calibres were enough to do
- serious structural damage to the bombers.
-
-
- Cheers RAF74 Buzzsaw
-

Which says that for WWII, the 50's worked fine. There are still applications today where they fit well.


Neal

XyZspineZyX
06-25-2003, 02:34 PM
tagert wrote:
-
- Well.. Im certain they based the tracor color and
- size off of something... maybe they have some camera
- footage... I find it hard to belive *this*
- aspect/topic has not been addrssed in the past?
-

More about the tracers.. Go fly a La-5 FN or any other plane with decent backwards visibililty. Then fire off a cannon round. For me, this resulted in me seeing a long trace of smoke extending almost BACKWARDS from my plane, as well as forward.

If my plane travels at 300 km/h, and a bullet is shot out from a barrel, it is logical that the relative speed of the bullet is much faster than mine. So, if the bullet, flying through the air, leaves a trace, I doubt it should extend backwards.

Afterall, a tracing bullet is just a bullet which has a small amount of heat-susceptible burner applied to the tip. When the bullet is fired off at high speed from the barrel, the heat caused by air resistance lits the incendiary material on, and the "burning bullet" continues to it's destination. So, the first part where the trace should be visible is when the material is lit. This happens around 2-3 meters in front of your aircraft. After that, you can spot the bullet by it's burning tip.

I have never seen a bullet which actually leaves a "smoke" trail behind, like some weapons in FB (mostly cannon/autocannon weapons and the german MGs). The burning tip head can be clearly seen in the german MG bullets, but the smoke trail they leave is not correct, I think.

-Celorfie

XyZspineZyX
06-25-2003, 02:44 PM
Salute

URL for Tony Williams site is:

http://www.quarry.nildram.co.uk/

Scroll down and you will find the article in question, entitled:

"WW2 Fighter Armament Effectiveness"

There are Muzzle velocity figures and weight listed on the various tables.

There are also a number of other articles which discuss related issues.

By the way, Hispano 20mm Mk V was rated as the best 20mm of the war. The Tempest V, equipped with 4 of these had a fearsome package versus either bomber or fighter.

Williams goes on to discuss the ideal WWII fighter armament, and decides an engine mounted 30mm and two wing root mounted 20mm would be the best solution, allowing for maximum effect versus either heavy bombers or fighters. The TA-152 had this armament.


Cheers RAF74 Buzzsaw





Message Edited on 06/25/0301:46PM by RAF74Buzzsaw_XO

XyZspineZyX
06-25-2003, 02:48 PM
tagert wrote:
- STOP! That is it in a NUT SHELL! In the 40s every
- country in the world.. except the USA was within
- reach of a hostal countrys bomber. Hence the need
- for well rounded fighters, in that not only did they
- have to contend with fighters, but stop bombers.

Actually the likes of the P47, P38, and P39 were
designed to be interceptors, with the presumption
that they would also be facing bombers (hence the
37mm cannon in the P39) and the P51 was designed
for export.

Of the mainstay aircraft of the USAAF during
WW2, only the P40, which was an update of the P36,
was not really designed with the option of bomber
intercepts in mind.

- USA had no real threat in the long range bomber
- dept, hence most of our fighters were design around
- the idea of going after other fighters. Except for
- the pacific, and as Tony noted, the NAVY dabbled
- with 20mm, but for the most part, most of our AC
- were design around the idea of gonig after other
- fighters. with that premis, lets continue.

Also the USAAF used cannon
in a number of aircraft - the aforementioned P39
and P38, and in addition the P61 (which was
designed with a 4 20mm cannon main armament) and
some A20Gs (again 4 20mm cannon, although in this
case for ground attack).

- Which is what is needed to take out the likes of a
- B17.. but NOT a fighter! No need for a sledge hamer
- when a ball pean will do.

If the target is hard to catch, and you can get
one hammer blow in, but it takes 5 from the ball
pean, then the sledge hammer starts to look attractive!

The RAF seemed very happy with a 4 20mm set up
as the basis for most aircraft, and the Hispano II
and V had similar muzzle velocity and rate of fire
to the .50, but more destructive power, the reasoning
being that a short burst when actually on target
would do the job. With RAF planes you only had the
ammunition for a short burst, but a P47 with 4 20mm
cannon could have carried a fair bit of ammunition.

- But, higher velocity and higher hit probability is
- what is NECESSARY to take out a fast moving, fast
- jinking figher, as aposed to a level flying bomber
- trying to put it's eggs on target.

There comes a point when using many, many guns is
using a sledgehammer for this though :-)

As you increase the number of guns, there is a
diminishing return in terms of the chance of at
least one round hitting. You are never assured
of a hit in practical terms.

The number of rounds likely to hit increases rather
more linearly with total rate of fire.

So your chance of one hit increases slowly, but
number of hits quickly.

If your chance of hitting in a situation is 90%,
that might be good enough. But that might not be
enough rounds on target to down the plane. You
could double the number of guns, and that will
tend to double the number of hits, which might
be enough to down the target, but the chance of
at least one hit might only increase to 95%. I.e.
you are about as likely to hit the target, but
very much more likely to down it.

The alternative approach is to use the same number or
even less guns, that are more powerful. Provided your
chance of a hit remains sufficient, you might find
that one hit is enough to down the target.

So in the first example chance of a hit is initially
90%, chance of a kill 10%, given you are htting, so
the total chance of a kill is 9% With twice as many
guns( these are all notional figures!) the chance of a
hit is 95%, of a kill given a hit is 30%, so the
chance of a kill given a hit is 28.5%, say, but
a chance of a degradation in the plane of perhaps
three times that - 85%).

With a few big guns, the chance of hitting at all
might drop (and the drop is not a linear drop off
with ROF) might be 70%. But the chance of a kill
given you are htting might be 60%, so the total
chance of a kill is 40%. The chance of a degrading
(non killing) hit cannot exceed your chance to hit,
so cannot be greater than 70%

So you are less likely to hit, but more likely to
kill, potentially, but less likely to 'degrade'
the other plane.

Obviously the real numbers are different!

Then there are issues of gun weight, serviceability,
logistics, etc, etc.


- True of the Lw bombers... but by the time we got
- there, they were not crossing over the pond..

They were still flying combat missions, and were
required to be shot down when bombing allied troop
concentrations on the continent.

- Weight it NOT the only concern, The SIZE WAS! In
- that you could have 6x0.50s on a F4u but only
- 4x20mm. Take the 3x effectivness and what do you
- have
-
- 3x0.50cal = 20mm
-
- 4x20mm vs 6x0.50
-
- So four 20mm was like 12x0.50cals.. which makes it
- twice as *effective*... WHEN YOU GET A HIT!!!

The chance of a hit from 4 20mm cannon, versus
6 .50s (ROF per gun almost the same) is almost
identical, assuming there are no other ballistic
effects. Ogre showed that recoil on 20mm cannon
did mean greater dispersion. At short ranges, the
difference in the chance of at least one hit from
4 20mm cannon and 6 .50s may have been small.

XyZspineZyX
06-25-2003, 03:07 PM
kweassa wrote:
- In short, by mid-1943, no other air force had more
- need for a fighter with a multi-role purpose role
- than the USAAF/USN. The fighter-bomber aspect of
- USAAF fighters, is something unseen in the RAF or
- the LW.

The Tempest was a designed as able to perform
both the air superiority and fighter bomber roles.

The 190F certainly worked as a multirole platform
in its various guises.

The Me262 was earmarked for both the fighter
and fighter bomber roles.

It seems that other nations were looking
at multirole aircraft too!


- explained/justified by their actual use as the
- hunter-killer role. It's really a part of a very old
- debate - and the view I support is that the USAAF
- didn't particularly find anything wrong with .50s,
- and they just let the issue drift by.


It seems to be a big part of it.


- The RAF, who stopped worrying about German bombers
- since late 1942, never reverted to their 30
- calibres, nor did they take 50 calibres.

They would have quite liked an earlier option
on the 2 20mm, 2 .50 spitfires, but the guns
were not available. (The VC with 4 20mm cannon
was produced in fair numbers, but the Spitfire
was probably a bit marginal for squeezing in
4 20mm cannon).

-- The switch to MG151/20, occured way before the Allied bombing campaigns began. Wrong timeline.

The switch to 20mm cannon was in 1940 - the
MG151/20 just wasn't available at the time, so the
MGFF had to do.

- The problem is, increasing the numbers of guns and
- ammo load with faster velocity to, let's say, double
- the amount?... did not necessarily result in 100%
- increase in the hit rate. It wasn't that linear.

Totally agree - I've said the same so many times!


- 3) increased numbers of bullets flying through the
- air, via increased number of guns, means the
- increase in the hit probability was achieved through
- spreading apart the shots in a shotgun effect.

There is also the fact that the sighting of the
guns is still mostly in the same direction.

If you fire both barrels of a shotgun, the chance
of hitting the target doesn't actually increase
that much, as you still have to be pointing it
in pretty much the right direction no matter if
you fire one or two barrels. This is one of the
critical issues - doubling the number of projectiles
doesn't increase the chance of a hit much, but
can increase the number of hits, given a hit
has occured (Bayesian).


- Likewise, Adolf Galland was partially unsatisfied
- with the new Bf109F models introduced in 1941.
- Galland specifically notes that the reduction of
- firepower to the MG151/15 15mm cannons, would effect
- the average pilots severely.

Galland also reportedly said that HMGs were
basically window dressing to make the pilots feel
like they were doing something!

XyZspineZyX
06-25-2003, 07:55 PM
AaronGT wrote:
-
- Actually the likes of the P47, P38, and P39 were
- designed to be interceptors, with the presumption
- that they would also be facing bombers (hence the
- 37mm cannon in the P39) and the P51 was designed
- for export.

interceptors of fighters and light bombers, in that in the late 30s and early 40s there were no heavy long range bombers that could reach the USA. On the note of P51 As export, the Brits did go with the 4 20s but it was more for ground attack in that the allison could not do the hi alt stuff anyways.

- Of the mainstay aircraft of the USAAF during
- WW2, only the P40, which was an update of the P36,
- was not really designed with the option of bomber
- intercepts in mind.

Enh.. funny though, out of all of them the P40 probally dropped more light bombers than any of them early on in the pacific.

- Also the USAAF used cannon
- in a number of aircraft - the aforementioned P39
- and P38, and in addition the P61 (which was
- designed with a 4 20mm cannon main armament) and
- some A20Gs (again 4 20mm cannon, although in this
- case for ground attack).

Enh... funny though, out of those two they were use more in gnd attack roals... Well, not so much for the P38, it got alot of a2a use in the pacific where Im sure the 20 can in handy on bombers.

-
-- Which is what is needed to take out the likes of a
-- B17.. but NOT a fighter! No need for a sledge hamer
-- when a ball pean will do.
-
- If the target is hard to catch, and you can get
- one hammer blow in, but it takes 5 from the ball
- pean, then the sledge hammer starts to look
- attractive!

Alot of "if's" in that, and my contention from the start is a ball pean if FINE, in that it will dmg it enough to take it out of the fight, and let time and gravity do the rest. That is to say, you dont need the sledge to blow it to bits! The damage due to the ball pean that took it out of the fight along with the impact of the ground will have the same end result.. BLOW TO BITS. Also keep in mind that you have more ammo with ball pean, thus, you can do this more than once, which was the goal of the escorts, take as many as you can out of the fight, and by fight I mean get them off the bombers you are escorting. That may sound funny in the context of the sim experance everyone is use to, where guys will continue to fight with a figher on thier six, tracers flying by, and smoke and fire coming out from under the hood... and Im sure there were a few cases like that in real war.. but the NORM would have been to break off the attack of the bombers and evaid the escorts.. in that in real life most people realise they only have one life, unlike people who play sims.


- The RAF seemed very happy with a 4 20mm set up
- as the basis for most aircraft,

And the RAF's basis roll was to protect the UK from bombers, the USAAF's roll was to escort bombers, we had nothing to do with protecting the UK, hence no real need to have guns mounted for taking out bombers.. only other fighters and light gound targets.


- and the Hispano II and V had similar muzzle
- velocity and rate of fire to the .50, but
- more destructive power,

similar... well, considering the fact that kenitic energy componet of velocity is squared, a small change in velocity makes a very big difference. And agin, more destructive power to the point of over kill is just that. Better to increase you odds of a hit with a ball pean, in that gravity will do the rest.


- the reasoning being that a short burst when
- actually on target would do the job.

WHEN, that is key!


- With RAF planes you only had the
- ammunition for a short burst, but a P47 with 4 20mm
- cannon could have carried a fair bit of ammunition.

Could... but WE were not worried about bombers, we were worried about keeping fighters off the bombers.

- There comes a point when using many, many guns is
- using a sledgehammer for this though :-)

Disagree.

- As you increase the number of guns, there is a
- diminishing return in terms of the chance of at
- least one round hitting.

What? I Disagree, please explain your reasoning here, this is 180 out of what I consider to be common sense... What ifno are you basing that statement on?

- You are never assured of a hit in practical terms.

True.. for both cannons and MG, but, with all other things constant, with more of EITHER you increase your chance of a hit... Right?


- The number of rounds likely to hit increases rather
- more linearly with total rate of fire.
- So your chance of one hit increases slowly, but
- number of hits quickly.

What? I Disagree, please explain your reasoning here, this is 180 out of what I consider to be common sense... What ifno are you basing that statement on?


- If your chance of hitting in a situation is 90%,
- that might be good enough. But that might not be
- enough rounds on target to down the plane. You
- could double the number of guns, and that will
- tend to double the number of hits, which might
- be enough to down the target, but the chance of
- at least one hit might only increase to 95%.

I see alot of percentages being tossed around... but they seem to be pulled out of thin air? Where are you gettnig these numbers that your attaching to the obious? I agree your chance of a hit imprvoes with more guns, but I dont agree with your 90% and 95% in that I dont see how you come up with that number.

- I.e. you are about as likely to hit the target,
- but very much more likely to down it.

Dont know about the likly part, but I do agree that more guns means more chance of a hit.

- The alternative approach is to use the same number
- or even less guns, that are more powerful. Provided
- your chance of a hit remains sufficient, you might
- find that one hit is enough to down the target.

If it remains sufficient, which I doubt, couple that with the fact that bigger guns typically means smaller ammo counts. Thus, you dont have as many rounds to PLAY WITH! By PLAY WITH I mean you could pop off a few ronds to see if they are going where your aiming, once ON TARGET give it a good burst... Where as with less ammo, you have to rely more on being a good aim from the get go, in that you dont have ammo to spare. And this is all with regards to fighter on fighter, not fighter on bomber.. fighter on bomber is easier in the aim dept, in that it is moving slower, and, not jinking around to evaide.


- So in the first example chance of a hit is initially
- 90%, chance of a kill 10%, given you are htting, so
- the total chance of a kill is 9% With twice as many
- guns( these are all notional figures!) the chance of
- a hit is 95%, of a kill given a hit is 30%, so the
- chance of a kill given a hit is 28.5%, say, but
- a chance of a degradation in the plane of perhaps
- three times that - 85%).

notional... you mean nominal? Eitherway, what part of thin air are you grabbing them from? I would like to look at that thin air and understand it a bit more! /i/smilies/16x16_smiley-wink.gif

- With a few big guns, the chance of hitting at all
- might drop (and the drop is not a linear drop off
- with ROF) might be 70%. But the chance of a kill
- given you are htting might be 60%, so the total
- chance of a kill is 40%. The chance of a degrading
- (non killing) hit cannot exceed your chance to hit,
- so cannot be greater than 70%

Again.. what part of thin air are you grabbing these numbers from? Im not saying they are wrong, I just dont buy them without some sort of calcuation or data to back them up.

- So you are less likely to hit, but more likely to
- kill, potentially, but less likely to 'degrade'
- the other plane.

Maybe.. if those numbers are based on more than thin air.

- Obviously the real numbers are different!

Ill bet.

- Then there are issues of gun weight, serviceability,
- logistics, etc, etc.

True, and dont forget, the whole HE round that the Lw boys like to bring up, that extra complexity will lower it's reliablity.

- They were still flying combat missions, and were
- required to be shot down when bombing allied troop
- concentrations on the continent.

True, but as we move into france the RAF came along and took up that role too. That and most of the German bombers were not of the HEAVY bomber status, like a B17, thus the 50 cals were found to be good to go!

- The chance of a hit from 4 20mm cannon, versus
- 6 .50s (ROF per gun almost the same) is almost
- identical, assuming there are no other ballistic
- effects.

But you cant assume that, the bigger rounds are sure to have more drag, that and you say allmost, keep in mind with regrads to velocity of the round... A LITTLE GOES A LONG WAY with regards to DESTRUCTIVE POWER! It is a squared term!!

- Ogre showed that recoil on 20mm cannon
- did mean greater dispersion. At short ranges, the
- difference in the chance of at least one hit from
- 4 20mm cannon and 6 .50s may have been small.

Doubt it.


TAGERT
-------------------------------------------------------------------------------------------------------
If WAR was not the ANSWER.. Than what the H was your QUESTION?

XyZspineZyX
06-25-2003, 10:39 PM
the final marks of the spitfire rested with 4 20mm cannons, i belive the mk 24 was the last one.

I would take cannons any day over machine guns, cannons when they hit will have 3 times the power of a single .50 hit, and that power is concentrated in one place, 3x the power hitting a wingspar is pretty good where as 3x .50 hits to equal one 20mm is going to be spread everywhere.

The .50s are more useful for sprey and prey but for someone who can get his guns on target the 20mm is better because it will take them down quicker. I belive the 190 started as a fighter it had 4 20mms and proved very effective.

http://lamppost.mine.nu/ahclan/files/sigs/spitwhiners1.jpg

XyZspineZyX
06-25-2003, 11:40 PM
tagert wrote:
- interceptors of fighters and light bombers, in that
- in the late 30s and early 40s there were no heavy
- long range bombers that could reach the USA.

You have to remember that there were US assets
in areas that could be potentially reached by
heavy bombers, not part of the continental USA,
and US aircraft development had to have an eye
on that. The Philipines is a prime example of this.
Plus despite there being no heavy bombers capable
of hitting the lower (only) 48 states at the time,
an eye was kept on the potential threat. After
all the threat against the continental USA from
light bombers was also rather low in the late 1930s
and early 1940s.

- Enh.. funny though, out of all of them the P40
- probally dropped more light bombers than any of them
- early on in the pacific.

One of those things!

- Alot of "if's" in that,

That's what happens when you start dealing with
probabilities.

- and my contention from the
- start is a ball pean if FINE, in that it will dmg it
- enough to take it out of the fight,

And it is a contentious issue. To be sure you
really need to simulate all the dispersion, etc.,
in all situations. Ogre has done some of this
work in terms of the dispersion at various ranges,
but really to get a full picture you need to model
all the features of combat, so you basically come
down to seeing what happens in something like FB.
The problem seems to be is that if a gun doesn't
perform as people assume it should, people sometimes
blame the sim, rather than wondering if it could
also be accurate. Of course it's very hard to know
which of the two it is.

- gravity do the rest. That is to say, you dont need
- the sledge to blow it to bits! The damage due to the
- ball pean that took it out of the fight along with
- the impact of the ground will have the same end
- result.. BLOW TO BITS.

Actually there is a difference - if the ball pean
takes the plane out of the fight, but the pilot
survives, it is less effective.

- Also keep in mind that you
- have more ammo with ball pean,

Actually if you need 12 .50s to have the same
damaging power as 4 20mm cannon, then you have
a huge weight of .50s that could have been used
for ammunition. So you might actually end up
with the ball pean having more bullets, but
a shorter firing time than you could have had.
In any case, you need to measure the number
of seconds of firing required to disable the
target and remove it from the fight rather than
concentrate on the quantity of ammunition. If
one burst from a cannon does what it takes two
from the .50, then the .50 needs twice as
much ammo to keep up (plus you need to be in
a firing position twice, perhaps).

- more than once, which was the goal of the escorts,
- take as many as you can out of the fight,

With an escort that long firing time was helpful.
With the P47, I've done some rough (but not too
rough) calculations, which suggest that if it had
been armed with 4 20mm cannon then it would have
had firing time close to that of the normal .50
load, or about 2/3 the max ammo load, and possibly
longer. (This is based on the weight of guns
and ammo in both cases, and a rough appraisal of the
volume of wing devoted to the ammunition storage,
and neglecting the potential extra volume vacated
by guns).

With the P51B, you'd have to take a drop in
firing time to go for a 4 20mm set up. Arguably
a 2 20mm setup would be of greater offensive power
than 4 .50s, though, although by that point the
ROF is getting to be marginal.


- fight I mean get them off the bombers you are
- escorting. That may sound funny in the context of
- the sim experance everyone is use to, where guys
- will continue to fight with a figher on thier six,
- tracers flying by, and smoke and fire coming out
- from under the hood... and Im sure there were a few
- cases like that in real war.. but the NORM would
- have been to break off the attack of the bombers and
- evaid the escorts.. in that in real life most people
- realise they only have one life, unlike people who
- play sims.

I understand the idea, and the .50s probably wasn't
too bad for that, but I think the advantages compared
to a smaller number of 20mm cannon was probably
marginal.

- And the RAF's basis roll was to protect the UK from
- bombers,

In 1940-41, yes, but apart from the Beidecke Blitz
of 1942, it wasn't a requirement from 1943 onwards,
when Rhubarbs and Circuses, and the like, became
what the RAF was doing - i.e. flying offensive
operations over France during daylight. (And of course
the nightbombing over Germany and occupied countries).

-- and the Hispano II and V had similar muzzle
-- velocity and rate of fire to the .50, but
-- more destructive power,
-
- similar... well, considering the fact that kenitic
- energy componet of velocity is squared, a small
- change in velocity makes a very big difference.

They are within a few 10s of m/s. In fact some
figures quote the Hispano II as having a higher
muzzle velocity than the M2 .50. The Hispano V
was about 30m/s slower (less than 5%) but had
a higher ROF than the Hispano II. The Hispano II
official ROF was only slightly behind that of the
official ROF for the M2. The Hispano V matched
the ROF.

- And
- agin, more destructive power to the point of over
- kill is just that. Better to increase you odds of a
- hit with a ball pean,

The odds are, in fact, not much increased.

-- With RAF planes you only had the
-- ammunition for a short burst, but a P47 with 4 20mm
-- cannon could have carried a fair bit of ammunition.
-
- Could... but WE were not worried about bombers, we
- were worried about keeping fighters off the bombers.

The 4 20mm set up also seemed to be very effective
for the RAF in shooting down fighters, which they
spent a lot of their time doing from 1943 onwards.

-- As you increase the number of guns, there is a
-- diminishing return in terms of the chance of at
-- least one round hitting.
-
- What? I Disagree, please explain your reasoning
- here,

It's a function of statistics.

- this is 180 out of what I consider to be
- common sense... What ifno are you basing that
- statement on?

Being a scientist, and having to use statistics
daily. Often probability and statistics seems
counterintuitive.

If you have one coin, and flip it, the chance
of getting a head is about 50%. If you flip
two coins, the chance of getting at least one
head is increased, but doubling the number of coins
does not double the chance of getting a head.
If it did then getting a head would be a certainty,
and it obviously isn't. In fact you'd need
an infinite number of coins to guarantee a head.

Doubling the number of samples doesn't linearly
increase the chance of getting an outcome. It's
a case of diminishing returns.

And in the case of the coins the events are independent,
whereas when aiming a plane, all the guns results are
somewhat interdepdent, as it is based on the plane
being pointing in the right direction.

To model that you'd have a series of coins. You
flip one. If you get a head, you flip the next, etc.
(Ok this is a bit too far in the other extreme, but
I couldn't think of a better analogy!)

I hope that makes the underlying processes a bit
clearer.

- True.. for both cannons and MG, but, with all other
- things constant, with more of EITHER you increase
- your chance of a hit... Right?

Yes, it increases it, but with a series of diminishing
returns. If you look at the first coin example, the
chance of getting at least one head with 4 coins and
with 8 coins isn't that much different. And that is a
set up that is generous to the 8 coin set up.

- What? I Disagree, please explain your reasoning
- here, this is 180 out of what I consider to be
- common sense... What ifno are you basing that
- statement on?

See above.

- I see alot of percentages being tossed around... but
- they seem to be pulled out of thin air?

They are just for illustrating the point.

- you gettnig these numbers that your attaching to the
- obious? I agree your chance of a hit imprvoes with
- more guns, but I dont agree with your 90% and 95% in
- that I dont see how you come up with that number.

They are just for the point of argument.

-
-- I.e. you are about as likely to hit the target,
-- but very much more likely to down it.
-
- Dont know about the likly part, but I do agree that
- more guns means more chance of a hit.

But less of an increase than you'd imagine.

- If it remains sufficient, which I doubt, couple that
- with the fact that bigger guns typically means
- smaller ammo counts.

If does, but less guns to use them up, and less guns
taking up weight, so the firing time may not decrease
if you, say, halved the number of .50s and replaced
them with 20mm cannon.

- Thus, you dont have as many
- rounds to PLAY WITH! By PLAY WITH I mean you could
- pop off a few ronds to see if they are going where
- your aiming, once ON TARGET give it a good burst...

If you have the same firing time (entirely possible)
then it doesn't make any difference.

-- So in the first example chance of a hit is initially
-- 90%, chance of a kill 10%, given you are htting, so
-- the total chance of a kill is 9% With twice as many
-- guns( these are all notional figures!) the chance of
-- a hit is 95%, of a kill given a hit is 30%, so the
-- chance of a kill given a hit is 28.5%, say, but
-- a chance of a degradation in the plane of perhaps
-- three times that - 85%).
-
- notional... you mean nominal?

No, notional, for the sake of illustrating the argument
and not to be taken as actual, real world figures.

- Eitherway, what part
- of thin air are you grabbing them from? I would like
- to look at that thin air and understand it a bit
- more!

The coin example's a good place to start.

For example with 4 coins the chance of at least one
head is 1-P(0 heads). P(0 heads) is easy to calculate -
it is 4 tails, the chance of which is 0.5*0.5*0.5*0.5,
or 0.0625, so the chance of at least one head is 93.75%.
The chance of at least one head with 8 coins is
1-0.5*0.5*0.5*0.5*0.5*0.5*0.5*0.5, or 99.6%. So by
doubling the number of coins the chance of at least
one head (or hit) has gone up from about 94% to 99.6%,
which isn't a huge jump.

The expected number of heads is different. With
4 coins it is about 2, with 8 coins, about 4. So the
expected number of heads (hits) has gone up linearly
in this case.

- Again.. what part of thin air are you grabbing these
- numbers from? Im not saying they are wrong, I just
- dont buy them without some sort of calcuation or
- data to back them up.

I hope the examples help. You get different points
of balance with different likelihoods of hitting, though.

Also since bullets are quantised, there comes a point
where a plane can fly through the gaps between the rounds.
Different maneouvers mean that different ROFs are marginal.

If you have a typical figher flying across you at
full deflection at about 300mph then any gun combo
with an ROF of around 900rpm should be able to score
at least one hit.

If the angle is not left to right then you need a
higher ROF, and so on.

So there is definitely a minimum cut off for ROF.
It is that above that ROF, you don't increase your
chances much.

I can't draw curves in here, so it is hard to explain...


- True, and dont forget, the whole HE round that the
- Lw boys like to bring up, that extra complexity will
- lower it's reliablity.

In terms of kinetic energy it is still quite potent,
though.

- But you cant assume that, the bigger rounds are sure
- to have more drag,

The surface area per mass drops as an object becomes
larger, which helps with bigger rounds, assuming the
same relative dimensions. In other words
if a round is fired at the same velocity then the
larger round actually has lower drag per unit kinetic
energy and will slow down less. However in the case
of 20mm rounds they were not of the same relative
dimensions as a .50 round and were shorter in
proportion to their mass than a .50 round. In other
words in the specific case of 20mm rounds from WW2,
the drag per kinetic energy was probably less good
than the .50

XyZspineZyX
06-25-2003, 11:45 PM
tagert wrote:
-- However, the turn of events in the 1950s,
-- inevitably forced the US air force to rapidly
-- abandon the "50cal agenda" and come to the
-- conclusion which other countries reached years
-- ago - the future of fighter armament
-- was with cannons over 20mm.
-
- DING! THANK YOU FOR MAKING MY POINT! As a quick
- historical reminder, by the 50s the USA was now
- comming within reach of long range bombers... Hence
- the need to take out long range bombers.

Actually the problem was the lack of ease of being
able to down Mig-15s in Korea which demonstrated
that the .50 was no longer considered sufficiently
effective air-to-air when mounted in a fighter
(and this was with the higher ROF M3 version, not the
M2 .50).







Message Edited on 06/25/03 10:47PM by AaronGT

Message Edited on 06/25/0310:47PM by AaronGT

XyZspineZyX
06-25-2003, 11:57 PM
HellToupee wrote:
- the final marks of the spitfire rested with 4 20mm
- cannons, i belive the mk 24 was the last one.

And it was the RAF's job to protect the UK from potential bombers.

- I would take cannons any day over machine guns,

Ok.

- cannons when they hit

WHEN

- will have 3 times the power of a single .50 hit,

Maybe, do you have some mass and velocity and kenitic enery equations to back that up? The eq is easy, getting the data should be easy too.

- and that power is concentrated in one place,

Which is not allways a good thing.

- 3x the power hitting a wingspar is pretty good

Enh.. maybe. Wingspars were designed to distribute the load pretty well. Thus it could be argued that a hit in one spot is less damaging then many smaller hits in many spots. That statement is base on the premis that these sims DONT model the effect of the forces on the wings!!! That is key, to my best knowledg the damage model simply sums up the damage in a spot, when the majic number is reached, it breaks. Where as in real life a little damage here, a little damge there applys some force and the wing might fail faster than alot of damage in one spot.

- where as 3x .50 hits to equal one 20mm is going
- to be spread everywhere.

Exactally! And the point is a alluminm SPAR is going to be like butter to a 20mm or a 0.50 cal, both will take out enough to cause it to fail. That and the spred everywhere means you have more of a chance of hitting it, and more of a chacne of hitting other vital areas, MULTIPLE systems.

- The .50s are more useful for sprey and prey

DING! And when you consider the state of WWII targeting systems... i.e. EYEBALL, BRAING, and GUNSIGHT there was alot of praying going on!

- but for someone who can get his guns on target

who can, not all could.

- the 20mm is better because it will take them
- down quicker.

Your missing one of my key points... in a sim that might be important.. but in WWII for the US escorts that was not what was important!!! All they had to do was get them off the B17s! Now, I know you all are very brave in these sims what with the re-spawn feature and all.. Which is why you will press on the attack of a B17 formation with six P51s spraing thousands of rounds over your sholder while your engine is smoking like a factory... BUT in WWII that was hardly the NORM!! A few rounds passing by the canopy of a Fw190 or Bf109 was enought to cause them to break off the attack of the B17s! Let alone a few passing threw the canopy!!

- I belive the 190 started as a fighter it had 4 20mms
- and proved very effective.

Your mising another one of my key ponits, every maker of fighters in WWII was concerned with bombers that could reach thier capitals... EXCEPT FOR THE USA!! There was no heavy bomber in the late 30s or early 40s that could reach us in the USA. Thus no real need for heavy guns to take out a heavy bomber. 0.50 cals were more then good enough for the job at hand, fighters and light bombers. Had we had to face our own heavy B17s we probaly would have had more AC like the P38s with the mix.



TAGERT
-------------------------------------------------------------------------------------------------------
If WAR was not the ANSWER.. Than what the H was your QUESTION?

XyZspineZyX
06-25-2003, 11:58 PM
tagert wrote:
- AaronGT wrote:
--
-- Actually the likes of the P47, P38, and P39 were
-- designed to be interceptors, with the presumption
-- that they would also be facing bombers (hence the
-- 37mm cannon in the P39) and the P51 was designed
-- for export.
-
- interceptors of fighters and light bombers, in that
- in the late 30s and early 40s there were no heavy
- long range bombers that could reach the USA. On the
- note of P51 As export, the Brits did go with the 4
- 20s but it was more for ground attack in that the
- allison could not do the hi alt stuff anyways.
-

Wht did the USAAF give a contract to Lockheed in 1937 for an interceptor?

"Lockheed was invited along with Boeing, Consolidated, Curtiss, Douglas, and Vultee to take part in a USAAC design competition X-608 for a twin-engined high-altitude interceptor. The specification called for a maximum speed of at least 360 mph at 20,000 feet and 290 mph at sea level, an endurance at full throttle of one hour at 20,000 feet, and the ability to take off and land over a 50-foot obstacle within 2200 feet. "

Or the P-47?

"The P-47 as originally conceived was quite different from the aircraft which was ultimately to emerge from the Republic factories. On August 1, 1939, Kartveli, in response to an official requirement, proposed a lightweight high-altitude interceptor to the USAAC under the company designation of AP-10."

The USA was not involved in WW2 yet.



http://www.wpafb.af.mil/museum/air_power/ap18a.jpg

XyZspineZyX
06-26-2003, 06:11 AM
AaronGT wrote:
- You have to remember that there were US assets
- in areas that could be potentially reached by
- heavy bombers, not part of the continental USA,

No, you have to remember that the defence of the UK was left upto the RAF! The USAAF had nothing to do with it, all we did prior to normandy was escort bombers into Germany.

- and US aircraft development had to have an eye
- on that.

They did! They just realised that nobody we faced had the likes of a heavy B17 like bomber... All there bombers we light and medium in comparson. And the 50 was a the perfect inbtween weapon! In that it was found that MG was more than enough for those bombers.

- The Philipines is a prime example of this.

A prime example of how good the 50s worked on light and medium bombers.

- Plus despite there being no heavy bombers capable
- of hitting the lower (only) 48 states at the time,
- an eye was kept on the potential threat. After
- all the threat against the continental USA from
- light bombers was also rather low in the late 1930s
- and early 1940s.

Exactally.

- One of those things!

Life is funny like that!

- That's what happens when you start dealing with
- probabilities.

Nope! Even probabilities have to have a data base to work from, otherwise they are just W.A.G.s

- And it is a contentious issue. To be sure you
- really need to simulate all the dispersion, etc.,
- in all situations. Ogre has done some of this
- work in terms of the dispersion at various ranges,
- but really to get a full picture you need to model
- all the features of combat, so you basically come
- down to seeing what happens in something like FB.
- The problem seems to be is that if a gun doesn't
- perform as people assume it should, people sometimes
- blame the sim, rather than wondering if it could
- also be accurate. Of course it's very hard to know
- which of the two it is.

Agreed.

- Actually there is a difference - if the ball pean
- takes the plane out of the fight, but the pilot
- survives, it is less effective.

Disagree.

- Actually if you need 12 .50s to have the same
- damaging power as 4 20mm cannon, then you have
- a huge weight of .50s that could have been used
- for ammunition. So you might actually end up
- with the ball pean having more bullets, but
- a shorter firing time than you could have had.

Your missing one of my main points, you dont need 12 fiftys, because you DONT NEED THE SAME DAMAGING POWER of 4 20s!! That is you dont have to blow it up into 1000 little bits, just enough damage to take it out of the fight, and gravity will do the rest.

- In any case, you need to measure the number
- of seconds of firing required to disable the
- target and remove it from the fight rather than
- concentrate on the quantity of ammunition.

Disagree. In that the number of seconds will depend on where it hits. All Im saying is the US was smart, in that by providing more ammo, and more guns they gave all thier pilots a better chance of getting a hit. And it dont take much to mess up aluminum. Thus, you could be a pilot with worse aim then the enmy pilot with 20mm and still get a hit that would take the fighter out.

- If one burst from a cannon does what it takes
- two from the .50, then the .50 needs twice as
- much ammo to keep up (plus you need to be in
- a firing position twice, perhaps).

Disagree. Until I see some numbers on the mass and velocitys of the 50cal vs 20mm we wont have a good feel for that. But again, note your assuming you get a hit with the 20.

- With an escort that long firing time was helpful.

DING!

- With the P47, I've done some rough (but not too
- rough) calculations, which suggest that if it had
- been armed with 4 20mm cannon then it would have
- had firing time close to that of the normal .50
- load, or about 2/3 the max ammo load, and possibly
- longer. (This is based on the weight of guns
- and ammo in both cases, and a rough appraisal of the
- volume of wing devoted to the ammunition storage,
- and neglecting the potential extra volume vacated
- by guns).

Yet the US never did that... Kind of makes you wonder why? I think they just realised that the 50 was a very good MG and a prety good cannon, in that fell right between the two in size and velocity.. ie THE PERFECT MIX!! That and the probally one of the things that makes the USA such a great place and leader in the world.. that mind set of IF IT AINT BROKE, DONT FIX IT!!!!


- With the P51B, you'd have to take a drop in
- firing time to go for a 4 20mm set up. Arguably
- a 2 20mm setup would be of greater offensive power
- than 4 .50s, though, although by that point the
- ROF is getting to be marginal.

Disagree.

- I understand the idea,

Worth stating though, in that most DONT! They think there sim experance is on par.. aint, and never will be!

- and the .50s probably wasn't too bad for that,

LOL!

- but I think the advantages compared
- to a smaller number of 20mm cannon was probably
- marginal.

Well, we have nothing to prove that.. Or do we? We had AC with cannons early on.. P39, P38.. but the P51 didnt... sure some tried cannons... but went back to the 50s.. That and when the P51B changed from 4x50s to the P51D... did they go for the cannons.. All the while knowing there were more an more US troops showing up on UK soil every day and in range of bombers... NOPE! They just added more 50s for a total of 6... Keep in mind 4x20mm had been mounted onto a P51 early on... yet... They went back to 4x50s... an EVEN SWAP.. and than later went to 6x50s instead of the better 20mm that were comming out... THAT SAYS ALOT FOR THE 50s!! So we can sit around and say we THINK it was MARGINAL... but clearly it wasnt to THEM!

- In 1940-41, yes, but apart from the Beidecke Blitz
- of 1942, it wasn't a requirement from 1943 onwards,

Not True.

- when Rhubarbs and Circuses, and the like, became
- what the RAF was doing - i.e. flying offensive
- operations over France during daylight. (And of
- course the nightbombing over Germany and occupied
- countries).

Agreed, onece we moved onto the content the RAF's defence (The UK did both) role encapslated those areas too, but for the most part we stayed on the escort and gnd attack roles, not defence.

- They are within a few 10s of m/s. In fact some
- figures quote the Hispano II as having a higher
- muzzle velocity than the M2 .50. The Hispano V
- was about 30m/s slower (less than 5%) but had
- a higher ROF than the Hispano II. The Hispano II
- official ROF was only slightly behind that of the
- official ROF for the M2. The Hispano V matched
- the ROF.

A few 10s of a m/s...? I got the meters per second thing (m/s) but what the H is 10s? On that note though, dont you find it funny... When the USA saw that the Merlin Engine was a better than the Alison, we had no problem adoptig it into service, Yet when this Hispano II came out we didnt use it... Even though the Mustang had been fitted with 20s by the Brits early on... What that tells me is the 50s were doing the job at hand just fine!

- The odds are, in fact, not much increased.

In fact huh? Is this some more of that special probalitys thin air stuff? Or do you have some math to back that up? If not, just want are you basing that statment on?


- The 4 20mm set up also seemed to be very effective
- for the RAF in shooting down fighters, which they
- spent a lot of their time doing from 1943 onwards.

True, but they were more worried about bombers.

--- As you increase the number of guns, there is a
--- diminishing return in terms of the chance of at
--- least one round hitting.
--
-- What? I Disagree, please explain your reasoning
-- here,
-
- It's a function of statistics.

A function huh? Well a function requires AT LEAST some input... thus, what part of thin air is your input from?

-- this is 180 out of what I consider to be
-- common sense... What ifno are you basing that
-- statement on?
-
- Being a scientist, and having to use statistics
- daily. Often probability and statistics seems
- counterintuitive.

Being an engineer I know how easy it is to disregard on set of data to make your statistics say what ever the H you want them to say.

- If you have one coin, and flip it, the chance
- of getting a head is about 50%.

Not ABOUT 50, it is 50!

- If you flip two coins, the chance of getting at
- least one head is increased, but doubling the
- number of coins does not double the chance of
- getting a head.
- If it did then getting a head would be a certainty,
- and it obviously isn't. In fact you'd need
- an infinite number of coins to guarantee a head.

The old coin senario wont do this justice, we aint talking heads vs tails here... What we are talking about is taking 6 pennys and throwing them at a spot on the wall... vs taking 4 nickles and throwing them at a spot on the wall... and the spot on the wall is moving... Now, I care if the heads side, or the tail side hit first, I just care if any of them hit at all.

- Doubling the number of samples doesn't linearly
- increase the chance of getting an outcome. It's
- a case of diminishing returns.
- And in the case of the coins the events are
- independent,

I realise it is diminishing returns, but, you still have a better chance, it is not double, but it is better. And this is a perfect example of why most statics are not worht the paper they are printed on, in that by excluding some variables you can make them come out the way you want them to. You cant boil this down to one variable, ie HEADS (ON) or TAILS (OFF). If you want to do it more justace stand on the roof, drop you pennies from there onto a dog with a small target taped to his A while that dog is chasing a cat... THEN tell me how many pennys hit, let along hit heads up!

- whereas when aiming a plane, all the guns results
- are somewhat interdepdent, as it is based on the
- plane being pointing in the right direction.

Exactlly, which is why the coin toss does not fit this well.

- To model that you'd have a series of coins. You
- flip one. If you get a head, you flip the next, etc.
- (Ok this is a bit too far in the other extreme, but
- I couldn't think of a better analogy!)

LOL! Well, because this aint a simple one! There are alot of factors playing into this, and the coin toss, ie the FIST THING THEY TEACH YOU IN STATISTICS is way to simple of a modle for this!! Need to get into ch 9 with correlation ans stuf like that! But who has the data to feed into those types of equations?

- I hope that makes the underlying processes a bit
- clearer.

Only thing clear is that it is not a good example. I will admit that doubleing guns probally does not double your chances... but you would have to agree that it does improve you chance of a hit! But I would not be so bold as to state a number! espically one based off the chapeter one coin toss of statistics!!!

- Yes, it increases it, but with a series of
- diminishing returns. If you look at the first
- coin example, the chance of getting at least
- one head with 4 coins and with 8 coins isn't
- that much different. And that is a
- set up that is generous to the 8 coin set up.

Disagree, the coin toss is not good here.

- See above.

Did, and still dont!

- They are just for illustrating the point.

Funny, if only for illustrating... then why did you go with the 90% to 95%... instead of the 73.2% to 98%?


- They are just for the point of argument.

Typical statics work! <G>

- But less of an increase than you'd imagine.

No, I dont imagine a doubling of guns would give me a doubling of chance, I only know that my chance would be better! I have no hard number, nor will I toss one out for... how did you put it illustration, in that it might give some people the false impression that 4 out of 5 dentiets choose chrest... Notice they never said if the 4 out of 5 had stock in the chrest company! /i/smilies/16x16_smiley-wink.gif

- If does, but less guns to use them up, and less guns
- taking up weight, so the firing time may not decrease

Typically a cannon weighs more than a MG, so, dont know if I buy the whole less weight thing... But the Germans were very good at making light and fast cannons! So, that might be true for some.

- if you, say, halved the number of .50s and replaced
- them with 20mm cannon.

Not just weight, large rounds have larger volume, thus more wasted space between rounds, more space taking up per round, etc.. It was simple stuff like that which drove the US from the old M1 to the M16. Less accurate at long range, ture, but more ammo, higher velocity meant better chance of a hit and could carry more ammo. It really is that simple!

-- Thus, you dont have as many
-- rounds to PLAY WITH! By PLAY WITH I mean you could
-- pop off a few ronds to see if they are going where
-- your aiming, once ON TARGET give it a good burst...
-
- If you have the same firing time (entirely possible)
- then it doesn't make any difference.

You missed my point, not talking time, Im talking spare ammo to take a few practace shots... to WALK IT IN!! You can DO THAT when you have more ammo, you cant do that with less ammo.. or you could, but not as many times! That simple thing is what escorts were faced with... One P51 had to swat off many attackers...

- No, notional, for the sake of illustrating the
- argument and not to be taken as actual, real
- world figures.

Ah, well maybe you should say that before you post it! /i/smilies/16x16_smiley-wink.gif

- The coin example's a good place to start.

But not a good place to work from.

- For example with 4 coins the chance of at least one
-<snip>
- which isn't a huge jump.

But, they are really not independed, thus the coin toss example is not a good modle here.

- The expected number of heads is different. With
- 4 coins it is about 2, with 8 coins, about 4. So the
- expected number of heads (hits) has gone up linearly
- in this case.

Try 4 to 6! Still in the linear rane, or plato yet?

- I hope the examples help. You get different points
- of balance with different likelihoods of hitting,
- though.

Emmmm but I just dont buy the coin toss model for this.

- Also since bullets are quantised, there comes a
- point where a plane can fly through the gaps between
- the rounds.

DING DING DING!!!! EXACTALLY!!! That variable is not captured by the coin toss, and I think you would even agree that those gaps get smaller with more guns firing down range! Thus less room for the AC to fly through!!!

- Different maneouvers mean that different ROFs are
- marginal.

Huh? Tell that to Ek =1/2mv^2

- If you have a typical figher flying across you at
- full deflection at about 300mph then any gun combo
- with an ROF of around 900rpm should be able to score
- at least one hit.

Assuing the guns were pre firing, and that the pilot didnt have to react to something moving into his perifial vision, then his forward vision, then to pull the trigger... etc.

- If the angle is not left to right then you need a
- higher ROF, and so on.

Dont know if I buy that one yet...

- So there is definitely a minimum cut off for ROF.
- It is that above that ROF, you don't increase your
- chances much.

But your increase in Ek is.

- I can't draw curves in here, so it is hard to
- explain...

Try me.

- In terms of kinetic energy it is still quite potent,
- though.

Never said it wasnt, just noting that more complex system means more chance of failer.

- The surface area per mass drops as an object becomes
- larger, which helps with bigger rounds, assuming the
- same relative dimensions. In other words
- if a round is fired at the same velocity then the
- larger round actually has lower drag per unit
- kinetic energy and will slow down less.

Hmmmm area/mass... hmmmmmm area, a squared term, mass would be tied into the volume.. a cubed term... hmmmm Ill have to give that a little more thought..

- However in the case of 20mm rounds they were not
- of the same relative dimensions as a .50 round
- and were shorter in proportion to their mass
- than a .50 round. In other words in the specific
- case of 20mm rounds from WW2, the drag per kinetic
- energy was probably less good than the .50

Ill have to take your word fot it, in that Ill have to give this some more thought. But a larger diameter is going to have more surfce area, no way around that. but, one could taper the round more, limits to that too, but the length of the round... that could/would play into that area/mass thing, so a longer round would have a better Ek (ie Ek = 1/2mv^2) but in that equation, v is the driver! And in most physic's 101 classes they assume no drag anyways in all them projectile equations... So, it probally realy is depended on m and v.


TAGERT
-------------------------------------------------------------------------------------------------------
If WAR was not the ANSWER.. Than what the H was your QUESTION?

XyZspineZyX
06-26-2003, 11:04 AM
tagert wrote:
- AaronGT wrote:
-- You have to remember that there were US assets
-- in areas that could be potentially reached by
-- heavy bombers, not part of the continental USA,
-
- No, you have to remember that the defence of the UK
- was left upto the RAF!

I was talking about the threat of attack of US
assets outside the USA, specifically the Philipines.

In Europe, the USA had troops in Africa, Italy, and
France, that all, at various points, would need
protection from bombers.

- The USAAF had nothing to do
- with it, all we did prior to normandy was escort
- bombers into Germany.

Apart from Italy and North Africa...

- They did! They just realised that nobody we faced
- had the likes of a heavy B17 like bomber...

At the point of development of most of the US fighters
(P38, P47) Germany was heavily involved in its later
cancelled B bomber design. This meant that at the time
of the issuing of specifications it was possible that
Germany could have had a heavy 4 engined bomber by the
time the USA entered the war. In the end it didn't
(apart from the flawed He177 and limited production
Ju290, and the recce bomber Fw Condor) but it could
have had more potential than it did.

-- The Philipines is a prime example of this.
-
- A prime example of how good the 50s worked on light
- and medium bombers.

No, I meant that it is an example of an area that
could have been at threat from heavy bombers, had
they been developed.

-- Plus despite there being no heavy bombers capable
-- of hitting the lower (only) 48 states at the time,
-- an eye was kept on the potential threat. After
-- all the threat against the continental USA from
-- light bombers was also rather low in the late 1930s
-- and early 1940s.
-
- Exactally.

What I was saying was that the threat from light
bombers was as real as from heavy bombers. The safety
was in the relative distance of the continental USA
from threats. However assets such as the Philipines
were at threat from all sorts of threat. In the end
the first attack was by carrier borne light bombers,
of course.

- Nope! Even probabilities have to have a data base to
- work from, otherwise they are just W.A.G.s

I was trying to demonstrate the PRINCIPLE, not use
exact numbers.


-- Actually there is a difference - if the ball pean
-- takes the plane out of the fight, but the pilot
-- survives, it is less effective.
-
- Disagree.

The RAF found the critical problem in the Battle of
Britain was loss of pilots. Thus killing a pilot
was in a sense more important a task for the LW than
destroying the planes.

- Your missing one of my main points, you dont need 12
- fiftys, because you DONT NEED THE SAME DAMAGING
- POWER of 4 20s!!

Just use 2 20mm then - large weight saving.

-- In any case, you need to measure the number
-- of seconds of firing required to disable the
-- target and remove it from the fight rather than
-- concentrate on the quantity of ammunition.
-
- Disagree. In that the number of seconds will depend
- on where it hits.

Of course.

- All Im saying is the US was smart,
- in that by providing more ammo,

It is firing time that is the requirement, coupled
with destructive power. With 4 20mm cannon would
could equip the P47 with about the same firing time
and more destructive power, with likely no significantly
less chance of at least one hit, and likely a greater
chance of taking the target out with a burst.

This was the line taken by other nations, in using
cannon armament, even those not facing heavy bombers.

One of your points is that the USA didn't have to
face heavy bombers thus did not need to use 20mm
cannon. The RAF ALSO didn't encounter heavy bombers,
yet felt 20mm cannon worthwhile enough to use them
as the primary armament on most fighter aircraft.

- and more guns they
- gave all thier pilots a better chance of getting a
- hit.

Not significantly greater, though. The returns on
increasing number of guns is diminishing.

-- If one burst from a cannon does what it takes
-- two from the .50, then the .50 needs twice as
-- much ammo to keep up (plus you need to be in
-- a firing position twice, perhaps).
-
- Disagree. Until I see some numbers on the mass and
- velocitys of the 50cal vs 20mm we wont have a good
- feel for that.

The Hispano II has the same muzzle velocity, and
a much heavier round. It has more kinetic energy
per round.

- But again, note your assuming you get
- a hit with the 20.

As I keep saying, if you are in a firing position
where a .50 hit is likely with a 6 or 8 gun fighter,
then you are almost as equally likely to get a hit
with a 4 20mm cannon set up.

-
-- With an escort that long firing time was helpful.
-
- DING!
-
-- With the P47, I've done some rough (but not too
-- rough) calculations, which suggest that if it had
-- been armed with 4 20mm cannon then it would have
-- had firing time close to that of the normal .50
-- load, or about 2/3 the max ammo load, and possibly
-- longer. (This is based on the weight of guns
-- and ammo in both cases, and a rough appraisal of the
-- volume of wing devoted to the ammunition storage,
-- and neglecting the potential extra volume vacated
-- by guns).
-
- Yet the US never did that... Kind of makes you
- wonder why?

It is easier to maintain the current set up than
risk a new one. It was done with the F4U, however.
It also makes logisitics much easier if all the
ammunition you make is basically the same.

- I think they just realised that the 50
- was a very good MG and a prety good cannon, in that
- fell right between the two in size and velocity.. ie
- THE PERFECT MIX!!

So perfect the USN wanted cannon :-)

-- With the P51B, you'd have to take a drop in
-- firing time to go for a 4 20mm set up. Arguably
-- a 2 20mm setup would be of greater offensive power
-- than 4 .50s, though, although by that point the
-- ROF is getting to be marginal.
-
- Disagree.

Actually I was being pro .50 at this point.

- Well, we have nothing to prove that.. Or do we?

You can run simulations and get some information
from those. The stuff that Ogre did is part of
that sort of information. There are a large number
of variables at play, which makes the modelling
somewhat complex.

- We
- had AC with cannons early on.. P39, P38.. but the
- P51 didnt... sure some tried cannons... but went
- back to the 50s.. That and when the P51B changed
- from 4x50s to the P51D... did they go for the
- cannons.. All the while knowing there were more an
- more US troops showing up on UK soil every day and
- in range of bombers...

Not every decision made during WW2 was correct.
In many instances there were all sorts of competing
reasons. For example the Sherman was an adequate tank,
being derived from the M2 via the M3. Rather than go
all out for a new tank there and then, the US Army
decided to create volume production based on a
tried and tested design, relying on numbers to win
out.

With the .50 the design was tested and reliable.
Production in volume was possible. The logistics
were simplified in using one type in many aircraft.
Maintenance knowledge was simplified (although
the number of guns probably increased it again).
It was simpler to keep with the .50 that in
sufficient numbers could do a decent job. This does
not mean, however, that the .50 in multiple
mountings, was better than the 20mm cannon. This
is my argument - not that the .50 wasn't very good,
but that the more efficient installation for
air to air combat in WW2 was the 20mm cannon
installation (of at least 2 20mm cannon, as less
than that and hit probabilities do suffer).

- 50s for a total of 6... Keep in mind 4x20mm had been
- mounted onto a P51 early on... yet... They went back
- to 4x50s...

Actually it wasn't a case of going back to 4 .50s,
except in the sense that 4 .50s were part of the
4 .50, 4 .30 armament of the Mustang I.

The Mustang IA was for the RAF only.

The US continued its versions with .50s.

- an EVEN SWAP..

- and than later went to 6x50s

the A36 also had 6 .50s (although often the nose
guns were removed).

- instead of the better 20mm that were comming
- out... THAT SAYS ALOT FOR THE 50s!!

It says something for standardisation of armament.

- So we can sit
- around and say we THINK it was MARGINAL... but
- clearly it wasnt to THEM!

Because there were concerns in addition to air-to-air
effectiveness alone.

-- In 1940-41, yes, but apart from the Beidecke Blitz
-- of 1942, it wasn't a requirement from 1943 onwards,
-
- Not True.

Actually it is entirely true. Britain faced very little
bombing by Germany after the Beidecke Blitz. I can
dig up the figures on sortie per year if you like.

- Agreed, onece we moved onto the content the RAF's
- defence (The UK did both) role encapslated those
- areas too, but for the most part we stayed on the
- escort and gnd attack roles, not defence.

My point was more that the RAF had swapped to an
offensive role over Europe before Overlord. There
were few raids by German bombers of any size or
real intent to deal with.

- A few 10s of a m/s...? I got the meters per second
- thing (m/s) but what the H is 10s?

A few tens.


- On that note
- though, dont you find it funny... When the USA saw
- that the Merlin Engine was a better than the Alison,
- we had no problem adoptig it into service, Yet when
- this Hispano II came out we didnt use it...

The UK suggested the use of the Merlin AFAIK, to
allow the Mustang continued RAF service. Also AFAIK
the USA was already producing the Merlin by that point
(Packard Merlins were fitted in various other RAF
aircraft).

- In fact huh? Is this some more of that special
- probalitys thin air stuff?

If you want to call it that, then yes.

-- The 4 20mm set up also seemed to be very effective
-- for the RAF in shooting down fighters, which they
-- spent a lot of their time doing from 1943 onwards.
-
- True, but they were more worried about bombers.

I suppose the worry was still there, but they weren't
spending much time shooting at them over the UK.

[.. snip...]

-- If you have one coin, and flip it, the chance
-- of getting a head is about 50%.
-
- Not ABOUT 50, it is 50!

Only if the coin is fair, and if you discount the
small but non-zero chance of it landing on its edge.

- The old coin senario wont do this justice, we aint
- talking heads vs tails here...

It was only intended as a demonstration of how
the chance of a desired result does not increase
linearly with the number of samples.

With aircraft guns we don't have independent
actions, such as the coins, they are all partially
dependent on a single event (pointing the plane
in the right direction).

Perhaps another analogy would be to throw a dice,
and then throw the coins. If you throw a 6 you
get to flip the coins.

So your chance of at least one head with 4 coins
is (1/6)*(1-0.5^4) or about 16%. With 8 coins it is
(1/6)*(1-0.5^8) or 17%.

This is an attempt to give an analogy of the
requirement to aim correctly (the target area
is comparatively small).

These are just analogies. For a full and detailed
analysis of the .50 and 20mm you'd need to
take into account the dispersal patterns and so on,
with various sorts of attack and aiming scenarios.
Based on that modelling (such as Ogre has done,
although you'd need more scenarios) you can get
closer to the true figures. I don't have his
functions or figures to do those analyses.

In reality dispersion against a target gives you
a function rather than the simple 0.5 probablity
of a hit that is based on the weapon type and the
shape of the plane, the distance to target, and so on.

The dice term above is dependent on what the chance
of getting a suitable firing solution were for a pilot
in WW2 (rather harder to compute).

- What we are talking
- about is taking 6 pennys and throwing them at a spot
- on the wall... vs taking 4 nickles and throwing them
- at a spot on the wall... and the spot on the wall is
- moving... Now, I care if the heads side, or the tail
- side hit first, I just care if any of them hit at
- all.

And you'll find that if you do this then increasing
the number of coins has a lesser effect on your chance
of one hitting the spot than you think.

One experiment sometimes quoted is drawing a circle,
and then taking a number of sticks of the radius
of the circle and dropping them.
As you increase the number of sticks, the chances
of one of them crossing the circle increases, but
not linearly. The probability of a single stick
crossing is related to Pi (but I can't remember how
exactly).

- I realise it is diminishing returns, but, you still
- have a better chance,

Yes, but it can be a smaller increase than you seem
to think it is. To know exactly, I'd need to look
at Ogre's figures and do the calculations. If anyone
has any links to his site it would help. Or alternatively
a link showing dispersion for .50 and 20mm guns at
air-to-air ranges. Then I could write a simple program
and get some real numbers.


- better. And this is a perfect example of why most
- statics are not worht the paper they are printed on,
- in that by excluding some variables you can make
- them come out the way you want them to.

That's not my intention.

You cant
- boil this down to one variable, ie HEADS (ON) or
- TAILS (OFF).

it's an analogy only!!!!!

- If you want to do it more justace stand
- on the roof, drop you pennies from there onto a dog
- with a small target taped to his A while that dog is
- chasing a cat... THEN tell me how many pennys hit,
- let along hit heads up!

I have a cat. I could borrow the neighbours dog :-)

-- whereas when aiming a plane, all the guns results
-- are somewhat interdepdent, as it is based on the
-- plane being pointing in the right direction.
-
- Exactlly, which is why the coin toss does not fit
- this well.

I know. I said this. I just couldn't think of a better
analogy at the time!

- LOL! Well, because this aint a simple one! There are
- alot of factors playing into this, and the coin
- toss, ie the FIST THING THEY TEACH YOU IN STATISTICS
- is way to simple of a modle for this!! Need to get
- into ch 9 with correlation ans stuf like that! But
- who has the data to feed into those types of
- equations?

I thought of sometime a bit simpler (above)

- Only thing clear is that it is not a good example.

I'll see if I can get hold of some disperion figures
and knock up a program (I'll publish the source)
to show the differing chances of hitting (assuming
that you are aiming on or close to the target -
that one is hard to compute for all the possibilities
air-to-air) and run some simulations. That might
be a bit fairer.

- that it does improve you chance of a hit! But I
- would not be so bold as to state a number! espically
- one based off the chapeter one coin toss of
- statistics!!!

I'm not stating a number either - I've just been
tryinig to illustrate things with examples.

[.. snip... ]

- Typically a cannon weighs more than a MG, so, dont
- know if I buy the whole less weight thing...

The Hispano V doesn't weigh a great deal more than
a .50. 4 Hispano Vs weigh less than 8 .50s.

- But the
- Germans were very good at making light and fast
- cannons! So, that might be true for some.

True for the USSR too.

- Not just weight, large rounds have larger volume,
- thus more wasted space between rounds,

yep - took that into account too, as best I could
(only knowing the diameter of the rounds rather
than the catridges meant I had to estimate a bit,
assuming the catridge diameter scaled up similarly).

- You missed my point, not talking time, Im talking
- spare ammo to take a few practace shots...

If you have the same firing time, then you have
the same ability to take practice shots - i.e. you
total firing time is depleted equally in both
instances.

- IT IN!! You can DO THAT when you have more ammo,

Not if you have the same firing time!

- Try 4 to 6! Still in the linear rane, or plato yet?

It's not linear at any point. 0 coins - 0 chance.
1 coin - 0.5. 2 coins - 0.75, 3 coins 0.875,
4 coins 0.9375, 5 coins 0.96875, 6 coins - 0.985...
etc. It's asymptotic p(x) = 1 - 0.5^x.It never reaches
1.0

- Emmmm but I just dont buy the coin toss model for
- this.

It was an example of the diminishing returns from
repeated samples only.

- DING DING DING!!!! EXACTALLY!!! That variable is not
- captured by the coin toss,

No, it isn't.

- and I think you would
- even agree that those gaps get smaller with more
- guns firing down range!

Totally. But about a certain ROF, this stops
making a difference, like trying to dodge raindrops.
Above 900rpm in the full deflection example you
can't avoid being hit. There are other scenarios,
but by the time you get to 4 20mm cannon, it's
basically impossible to avoid at least one hit
if you fly the plane through the stream of rounds.

The question is spray-and-pray the best tactic,
a valid tactic, worthwhile having the option of?
I don't know the answer to that one.

-- Different maneouvers mean that different ROFs are
-- marginal.
-
- Huh? Tell that to Ek =1/2mv^2

I meant that there are difference chances to
'slip between the rounds' depending on the relative
maneouvering of the aircraft and their relative
orientations. For a 300ph basic full deflection shot
against a fighter, 900rpm will ensure at least 1 hit.
With an engagement with wing mounted guns, not at
convergence, with high relative roll, you need much
more ROF to be sure of at least one hit. (Note this
is about 900rpm combined from all guns).

- Assuing the guns were pre firing,

Yes, and that is what a pilot should do - anticipate.
Since there is a delay in the guns firing, and
the target would be across your sights for about
1/10 seond then prefiring would be a good idea anyway.

-- If the angle is not left to right then you need a
-- higher ROF, and so on.
-
- Dont know if I buy that one yet...

Most aircraft guns are mounted across the width
of the plane. If the target flies in at 45 degrees
then the effective time in front of a gun is reduced.
Thus you need a higher ROF to ensure at least one
hit from that gun. Since you can't be sure how
the guns are synchronised to each other, you can't
otherwise be sure that each gun might not miss
in turn. I.e. to be totally sure of a hit you need
to ensure that each gun can put out enough rounds
to be sure of hitting the plane on its own. To have
a good chance of hitting the plane, we are back
to the diminishing returns thing again.


-
-- So there is definitely a minimum cut off for ROF.
-- It is that above that ROF, you don't increase your
-- chances much.
-
- But your increase in Ek is.

That's got nothing to do with this part of the argument.

-
-- I can't draw curves in here, so it is hard to
-- explain...
-
- Try me.

You have a line that as you decrease the ROF drops
non linearly, but steadily, until it hits the critical
ROF, at which point it decays rapidly, and then tails
off. Like a culmulative score graph (ogive).

- Never said it wasnt, just noting that more complex
- system means more chance of failer.

That it does.

- Hmmmm area/mass... hmmmmmm area, a squared term,
- mass would be tied into the volume.. a cubed term...
- hmmmm Ill have to give that a little more thought..

It's also why, all other things being equal, a heavy
plane can accelerate faster in a dive.

- Ill have to take your word fot it, in that Ill have
- to give this some more thought. But a larger
- diameter is going to have more surfce area, no way
- around that. but, one could taper the round more,
- limits to that too, but the length of the round...

The mass increases as the cube of the dimension,
all other things being equal. But the 20mm round
is about half as long as you'd expect from a scaled
up .50 round. Plus it is not a solid projectile.
It has less mass than you'd expect, relative to its
surface area, than you would from simply scaling
the dimensions by 20:12.7. If the surface area
(and we assume drag does too, for a first approximation)
scales with the square of the dimension, and the
mass with the cube, then the ratio of mass:surface
area (and thus kinetic energy:drag) should increase
linearly with dimension. But perhaps with the 20mm
round we have some fraction of the mass we'd expect.
If we have less than 63% of the mass we'd expect from
just scaling up a .50 round, then the 20mm round
has more drag per unit kinetic energy.

XyZspineZyX
06-26-2003, 07:55 PM
S! All

The Discovery Channel has been running the series "The Color of War". In it they follow a Squadron of P47's from late 44 till the end of the war.

There is actual gun camara footage of P47 strike missions on german airdromes, convoys, trains/rail yards, bridges, and busting tanks.

The 47 pilots interviewed talked about how the Tiger Tanks would carry spare fuel drums behind the tank either on the tank itself or in a small trailer pulled by the tank.

Thunderbolt pilots would either strafe the fuel drums and ignite them or shoot at an angle behind the tank to ricochet the bullets up thru the thinner armor plate on the bottom of the tank.

A "1" second burst of the 8 .50 cal is supposed to have the equivelant of 13lbs of lead being fired at you.

I DO NOT think the power of 8 .50 cal is accurately modeled in FB on the P47 as to what these guns accomplished in real life.

XyZspineZyX
06-26-2003, 08:57 PM
If folks are not getting the right results from the 47s guns then theyu are missing..it's that simple.. If you hit right on a 2 second burst can set a plane on fire. You cant judge that by online play either..there is lag and all sorts of other network stuff like the other guys's connection, your connection, both processors, video cards..etc. Fly off line and put thise shots where they belong and see if that sucker doesnt light up.... /i/smilies/16x16_smiley-very-happy.gif

<CENTER>http://www.world-wide-net.com/tuskegeeairmen/ta-1943.jpg <marquee><FONT COLOR="RED"><FONT SIZE="+1">"Straighten up.......Fly right..~S~"<FONT SIZE> </marquee> http://www.geocities.com/rt_bearcat

<CENTER><FONT COLOR="ORANGE">vflyer@comcast.net<FONT COLOR>
<Center><div style="width:200;color:red;font-size:18pt;filter:shadow Blur[color=red,strength=8)">99th Pursuit Squadron

XyZspineZyX
06-26-2003, 10:40 PM
The .50 cal in FB are not undermodelled, it´s just a matter of convergence and ascociated firing ranges. The lethality (FL) of a gun can be estimated by multiplying the destructive power of it´s projectile and number of hits. For non-explosive bullets, destructive qualities are generally proportional to kinetic energy: half the mass of the projectile times the square of it´s velocity, whereas the velocity used should be the impact- not the muzzle velocity (V0), but here muzzle velocity will do for comparison. Weight of fire (WF), which is the total weight of projectiles that can be fired in one minute (assuming barrel limitations and ammuntion supply allows) is taken into the equation. The factor FL is proportional to the kinetic energy of each projectile and rate of fire. FL should be roughly indicative of the lethality of nonexplosive bullets fired at a specific rate from a given gun. Cannons are a somewhat different case, since much of the lethality of these weapons is derived from their explosive shells, and hence fragmentation, blast and incendiary effect. Therefore FL is a simple relative assessment of the destructiveness of machineguns, but it underrates the cannon in comparison.

Wf= lbs/min
Fl= Wf x V0² x 10 ^-8

.50-cal M2 (12.7 x 99)
Bullet Weight (lbs): .10
Rate of Fire (rds/min): 800
V0 (ft/sec): 2810
=================================
Weight of Fire (Wf): 80
Lethality (Fl): 6.4

The P-47D does have 8 x .50-cal M2, which equals an Fl factor of 51 if all machineguns are fired.

For comparison:

MG 131/13 (13 x 64)
Bullet Weight (lbs): .085
Rate of Fire (rds/min): 930
V0 (ft/sec): 2461
=================================
Weight of Fire (Wf): 79
Lethality (Fl): 4.8

MG 151/20 (20 x 81)
Bullet Weight (lbs): .25
Rate of Fire (rds/min): 780
V0 (ft/sec): 2592
=================================
Weight of Fire (Wf): 195
Lethality (Fl): 13.1

Note that fragmentation, blast and incendiary effect of 20mm cannon ammuntion is not taken account for.

It´s obvious that a large array of wing mounted machine guns with a relative low individual Fl rating will only deliver the maximum destructive effect to the target if the combined firepower can also be concentrated on the target.
Now the advent of wing-mounted guns led to increased problems with bullet dispersion, leaving large gaps in the bullet pattern at some firing ranges. The lethal bullet density was increased by a method known as harmonization (point or pattern) to increase the bullet density near a particular range (normally 700ft-800ft). Outside this harmonization envelope, and only a fraction of the firepower can be brought to bear on the target, and it takes alot more .50 cal rounds to achieve similar effect as a single 20mm HE hit.


============================
When it comes to testing new aircraft or determining maximum performance, pilots like to talk about "pushing the envelope." They're talking about a two dimensional model: the bottom is zero altitude, the ground; the left is zero speed; the top is max altitude; and the right, maximum velocity, of course. So, the pilots are pushing that upper-right-hand corner of the envelope. What everybody tries not to dwell on is that that's where the postage gets canceled, too.

XyZspineZyX
06-27-2003, 01:31 AM
It would be nice if this myth of shooting through the thin bottom of a Tiger would die. The bottom of a Tiger was 25mm or 1" thick or at a richochet angle thickness of ~ 100mm or 4".

If a .50" did such a good job there was no need for all those big calibre AT guns , eh?


BigKahuna_GS wrote:

-
- The 47 pilots interviewed talked about how the Tiger
- Tanks would carry spare fuel drums behind the tank
- either on the tank itself or in a small trailer
- pulled by the tank.
-
- Thunderbolt pilots would either strafe the fuel
- drums and ignite them or shoot at an angle behind
- the tank to ricochet the bullets up thru the thinner
- armor plate on the bottom of the tank.
-
-




http://www.wpafb.af.mil/museum/air_power/ap18a.jpg


http://www.wpafb.af.mil/museum/air_power/ap18a.jpg

XyZspineZyX
06-27-2003, 02:29 AM
MiloMorai wrote:
- It would be nice if this myth of shooting through
- the thin bottom of a Tiger would die. The bottom of
- a Tiger was 25mm or 1" thick

Only an inch? Huh, thought it was more than that! An inch would probaly be no proble for an 50 cal!

- or at a richochet angle thickness of ~ 100mm or 4".

Dont know where you came up with that number, but it is most likly based on a level tank and a diving aircraft... Consider this, a level flying aircraft and a tank just cresting a hill.. The belly is not exposed, and the incidence angle (richochet) i much smaller, if not zero.

- If a .50" did such a good job there was no need for
- all those big calibre AT guns , eh?

LOL! Well, I think it is safe to assume that 99 out of a 100 times they were not dealing with a tank cresting a hill!



TAGERT
-------------------------------------------------------------------------------------------------------
If WAR was not the ANSWER.. Than what the H was your QUESTION?

XyZspineZyX
06-27-2003, 02:32 AM
Bearcat99 wrote:
- If folks are not getting the right results from the
- 47s guns then theyu are missing..it's that simple..

Probally True!

- If you hit right on a 2 second burst can set a plane
- on fire.

True.

- You cant judge that by online play
- either..there is lag and all sorts of other network
- stuff like the other guys's connection, your
- connection, both processors, video cards..etc. Fly
- off line and put thise shots where they belong and
- see if that sucker doesnt light up..

Very good point! I have noticed that online I dont see the hit strikes as much as I do offline... Which makes it a little harder to walk it in.. Love it though when they do! Nutting like lighting up a Fw190 with what looks like a box full of XMAS light tied to it's "A"!



TAGERT
-------------------------------------------------------------------------------------------------------
If WAR was not the ANSWER.. Than what the H was your QUESTION?

XyZspineZyX
06-27-2003, 06:23 AM
Aaron GT wrote:
-- No, you have to remember that the de fence of the UK
-- was left upto the RAF!
-
- I was talking about the threat of attack of US
- assets outside the USA, specifically the Philipines.
-
- In Europe, the USA had troops in Africa, Italy, and
- France, that all, at various points, would need
- protection from bombers.

--SEE HERE--
Ah, I see the misunderstanding here. You are operating under the impression that NATIONS main purpose for building ARMYS is to protect ARMY'S ASSETS, Where as I'm operating under the impression that NATIONS main purpose for building ARMYS is to protect NATIONS! You have to understand two things for this to really make sense.. One in the 20,30,40 the USA had a very isolation attitude towards Europe and all their problems. TWO Americans, American government didn't then, and until 911 didn't give a RATS A** about A**ETS outside of the USA! Recent History proof, We didn't give a RATS A** when Bin Ladin bleu up that US Embcy.. and A**ET... We didn't give a RATS A** when Bin Ladin bleu up the USN COLE.. and A**ET... We didn't give a RATS A** UNTIL Bin Ladin bleu up something in the USA! That simple mind set played into every aspect of government, industry and peoples decisions. Read this twice, because in the rest of this post I going to simply say see above where it says --SEE HERE--.

- Apart from Italy and North Africa...

SEE ABOVE, where it says --SEE HERE--

- No, I meant that it is an example of an area that
- could have been at threat from heavy bombers, had
- they been developed.

SEE ABOVE, where it says --SEE HERE--

- What I was saying was that the threat from light
- bombers was as real as from heavy bombers.

Not to the lower 48.

- The safety was in the relative distance of the
- continental USA from threats.

DING DING DING... which is also why the whole isolation stance work pre 1950s+

- However assets such as the Philipines
- were at threat from all sorts of threat. In the end
- the first attack was by carrier borne light bombers,
- of course.

SEE ABOVE, where it says --SEE HERE--

- I was trying to demonstrate the PRINCIPLE, not use
- exact numbers.

Should note that than when doing so.

--- Actually there is a difference - if the ball pean
--- takes the plane out of the fight, but the pilot
--- survives, it is less effective.
--
-- Disagree.
-
- The RAF found the critical problem in the Battle of
- Britain was loss of pilots. Thus killing a pilot
- was in a sense more important a task for the LW than
- destroying the planes.

We didn't face the RAF, they were on our side.

-- Your missing one of my main points, you don't need 12
-- fiftys, because you DON'T NEED THE SAME DAMAGING
-- POWER of 4 20s!!
-
- Just use 2 20mm then - large weight saving.

Your still missing the point, you have to hit it first! And with more guns you have a better chance. Granted, there is a limit, and the gun has to be somewhat effective. And the 6x mix of .50s meets both limits with flying colors... pun intended!


-- Disagree. In that the number of seconds will depend
-- on where it hits.
-
- Of course.

A first! /i/smilies/16x16_smiley-wink.gif

- It is firing time that is the requirement, coupled
- with destructive power.

Agreed... ONCE YOU ARE ON TARGET AND GETTING HITS!! And that is another one of my points you keep side stepping... With more guns, you get more ammo down range, thus more chance of a hit, with smaller guns (i.e. not cannons) you can carry more ammo. Thus you have ammo to play with, by play with I mean you don't have to have PERFECT AIM!!! You could WALK THE ROUNDS ONTO TARGET!! Where as with bigger guns, and less ammo, you don't have ammo to spare! You have to have a beater AIM from the get go!! Which is why big guns and small ammo loads works very very VERY well on bombers... Bombers don't jink around like fighters... Thus you aim is much much easier to do.


- With 4 20mm cannon would could equip the P47 with
- about the same firing time and more destructive
- power, with likely no significantly
- less chance of at least one hit, and likely a
- greater chance of taking the target out with a burst.

Yet they never did it.. That and even the NAVY who installed them into F4us didn't continue with it. That says a lot for the .50s!

- This was the line taken by other nations, in using
- cannon armament, even those not facing heavy
- bombers.

Name one that didn't! All nations in WWII city faced attackers from bombers, except the USA! And when I say attack from bombers... I don't mean like doolittles raid!! That was more for moral than strategic!!

- One of your points is that the USA didn't have to
- face heavy bombers thus did not need to use 20mm
- cannon.

That and the .50 is close enough to cannon that it will do just fine, especially for ASSETS!!

- The RAF ALSO didn't encounter heavy bombers,
- yet felt 20mm cannon worth while enough to use them
- as the primary armament on most fighter aircraft.

Heavy, Medium, Light... NONE could get to the USA in any useful manor! When your factory, an ASSET is 5 miles from the border of a country you going to war with... YOU BEST BE DAM WORRIED ABOUT DROPPING ASAP! City cant get up and move like ARMYS, sad but true, thus SEE ABOVE, where it says --SEE HERE--

- Not significantly greater, though. The returns on
- increasing number of guns is diminishing.

But better none the less! And the gun count never reach a point of diminishing returns on USAAF aircraft.

- The Hispano II has the same muzzle velocity, and
- a much heavier round. It has more kinetic energy
- per round.

Yet we didn't use it.. That says a lot for the .50s.

- As I keep saying, if you are in a firing position
- where a .50 hit is likely with a 6 or 8 gun fighter,
- then you are almost as equally likely to get a hit
- with a 4 20mm cannon set up.

Like I keep saying, your assuming you have the aim to get the hits.. thus you are ignoring the hardest part! GETTING THE AIM TO GET THE HITS!! And, as I noted, smaller mg like the .50s with more ammo means you don't have to be as good of a shot, simple pull the trigger, and WALK THE ROUNDS ONTO THE AIRCRAFT! Cant do that, or at least can do it as many times in a ship with large guns and small ammo counts.. You have to be a good shot, -OR- be hunting BOMBERS that are much easier to draw an aim on.

- It is easier to maintain the current set up than
- risk a new one.
- It was done with the F4U, however.
- It also makes logistics much easier if all the
- ammunition you make is basically the same.

Agreed 100% something I have point out with regards to Williams sight and his fancy full "what if" scenario where he put together the dream machine of fighters. Totally disregards the facts of war in WWII. But, when faced with something that is BROKE!!!! WE FIXED IT!!! For example, did we stick with the Allison in the P51 after the Brits pulled our heads out for us and showed us the Merlin... NO!! Thus, not only do you have to understand the mind set of the USA than and now with regards to isolationism, but, the tried and true notion of IF IT AINT BROKE DON'T FIX IT!! The .50s work find on the bombers we faced, and great on the fighters we faced. They were the perfect mix in so many many ways!


- So perfect the USN wanted cannon :-)

So perfect were they that they stopped using them /i/smilies/16x16_smiley-wink.gif Granted, in the 50s they brought them back to the F4u, but by that time it was devoted to ground attack roles... If you think a bomber is easy to draw a bead on, try a truck! (and no, I'm not saying it was easy, Ill bet I couldn't do either in the heat of battle, but it had to be easier than a bomber)

--- With the P51B, you'd have to take a drop in
--- firing time to go for a 4 20mm set up. Arguably
--- a 2 20mm setup would be of greater offensive power
--- than 4 .50s, though, although by that point the
--- ROF is getting to be marginal.
--
-- Disagree.
-
- Actually I was being pro .50 at this point.

Disagree /i/smilies/16x16_smiley-wink.gif

- You can run simulations and get some information
- from those. The stuff that Ogre did is part of
- that sort of information. There are a large number
- of variables at play, which makes the modelling
- somewhat complex.

CHA CHING! Yet.. you think a coin toss statistics model with fit?

- Not every decision made during WW2 was correct.

Agreed 100%

- In many instances there were all sorts of competing
- reasons. For example the Sherman was an adequate
- tank, being derived from the M2 via the M3. Rather
- than go all out for a new tank there and then, the
- US Army decided to create volume production based on a
- tried and tested design, relying on numbers to win
- out.

Your point? Because it worked didn't? What was bad about it? Oh, wait, I see, you think the only factor was production... Don't forget had we build a 60 ton KING TIGER like tanks it would have sank the transports bringing it across the pond from UK to FRANCE!

- With the .50 the design was tested and reliable.
- Production in volume was possible. The logistics
- were simplified in using one type in many aircraft.
- Maintenance knowledge was simplified (although
- the number of guns probably increased it again).
- It was simpler to keep with the .50 that in
- sufficient numbers could do a decent job. This does
- not mean, however, that the .50 in multiple
- mountings, was better than the 20mm cannon. This
- is my argument -

And your.. i.e. THAT argument would be true for the Allison Engine... Yet we didn't keep using it in the Mustang! Again, a case of if it aint broke, don't fix it!

- not that the .50 wasn't very good,
- but that the more efficient installation for
- air to air combat in WW2 was the 20mm cannon
- installation (of at least 2 20mm cannon, as less
- than that and hit probabilities do suffer).

Only more efficient once you start getting hits. Which is the hardest part of getting a kill. Couple that with the fact that you don't have to blow it to bits to take it out of the fight, and it becomes more clear why we stuck with the .50s

- Actually it wasn't a case of going back to 4 .50s,
- except in the sense that 4 .50s were part of the
- 4 .50, 4 .30 armament of the Mustang I.

Exactally. Tried it, didn't improve things all the much if at all, thus stick with the logistics flow.

- The Mustang IA was for the RAF only.
-
- The US continued its versions with .50s.

Never said it wasn't or didn't.

- the A36 also had 6 .50s (although often the nose
- guns were removed).

True, them Brits did like the mix, cannons for bombers, Mg for fighters

- It says something for standardisation of armament.

That too, but it says more about.. IF IT AINT BROKE DON'T FIX IT!

- Because there were concerns in addition to
- air-to-air effectiveness alone.

Something I have been saying from the get go.. If you think .50s were good in the air, they were even better on the gnd targets!

--- In 1940-41, yes, but apart from the Beidecke Blitz
--- of 1942, it wasn't a requirement from 1943 onwards,
--
-- Not True.
-
- Actually it is entirely true. Britain faced very
- little bombing by Germany after the Beidecke Blitz.
- I can dig up the figures on sortie per year if you like.

Ah, I see your mistake, your statement says it after the fact... Which is easy, but at the time they didn't know for sure. Kind of like we didn't expect the battle of the budge. Thus like the good Brits that they were, they stayed sharp and ready!

- My point was more that the RAF had swapped to an
- offensive role over Europe before Overlord. There
- were few raids by German bombers of any size or
- real intent to deal with.

Again, knowledge after the fact... Allways can be used to make people look stupid. Hind sight is 20, 20.. The fact is the possibility of a bombing raid was there.

- A few tens.

Ah! Well, true of one cannon.

-- On that note
-- though, don't you find it funny... When the USA saw
-- that the Merlin Engine was a better than the Alison,
-- we had no problem adoptig it into service, Yet when
-- this Hispano II came out we didn't use it...
-
- The UK suggested the use of the Merlin AFAIK, to
- allow the Mustang continued RAF service. Also AFAIK
- the USA was already producing the Merlin by that
- point (Packard Merlins were fitted in various
- other RAF aircraft).

Is what I'm saying, but, you missed the point. Point being when something didn't work, logistics, production, experience or not, we changed it to fix it! The .50s were never broke, they shot down fighters and bombers great! That and our factory, city, and citizens were not within five miles on an enemy bomber base... So, even if it did take us a little longer (which I aint saying it did) we had plenty of time to shoot it down before it got to the USA! Oh, and SEE ABOVE, where it says --SEE HERE--! /i/smilies/16x16_smiley-wink.gif

- If you want to call it that, then yes.

LOL! I just call em as I see em! /i/smilies/16x16_smiley-wink.gif

- I suppose the worry was still there, but they
- weren't spending much time shooting at them over
- the UK.

No supposing about it!

- Only if the coin is fair, and if you discount the
- small but non-zero chance of it landing on its edge.

LOL! And they say I like to stretch the story over admitting I was wrong! /i/smilies/16x16_smiley-wink.gif

- It was only intended as a demonstration of how
- the chance of a desired result does not increase
- linearly with the number of samples.

A bad demo imho! I've seen others state it like fact, Ill give you credit, at least you admit it is not a good model!!

- With aircraft guns we don't have independent
- actions, such as the coins, they are all partially
- dependent on a single event (pointing the plane
- in the right direction).
-
- Perhaps another analogy would be to throw a dice,
- and then throw the coins. If you throw a 6 you
- get to flip the coins.

LOL! I like it, sounds like it would account for that initial aim of a cannon driver.. But to simulate the .50s driver you would have to let him role the dice more than once, in that he has more ammo. /i/smilies/16x16_smiley-wink.gif

- This is an attempt to give an analogy of the
- requirement to aim correctly (the target area
- is comparatively small).
-
- These are just analogies. For a full and detailed
- analysis of the .50 and 20mm you'd need to
- take into account the dispersal patterns and so on,
- with various sorts of attack and aiming scenarios.

Agreed 100%

- Based on that modelling (such as Ogre has done,
- although you'd need more scenarios) you can get
- closer to the true figures. I don't have his
- functions or figures to do those analyses.

And we haven't even begun to model the aim of the pilot, they are just assuming the same aim and unlimited ammo.

- In reality dispersion against a target gives you
- a function rather than the simple 0.5 probability
- of a hit that is based on the weapon type and the
- shape of the plane, the distance to target, and so
- on.

Agreed!

- The dice term above is dependent on what the chance
- of getting a suitable firing solution were for a
- pilot in WW2 (rather harder to compute).

LOL! My joke was not that far off.. Ok, now let the .50 drivers roll the dice more than the cannon drivers, and we have a pretty good model!

- And you'll find that if you do this then increasing
- the number of coins has a lesser effect on your
- chance of one hitting the spot than you think.

Nope! In that I don't think it would be a linear improvement, but I KNOW IT WOULD BE BETTER NONE THE LESS!!!! And when you consider how much damage one .50 round can have in the right place, I think it would be clear that getting the hit is the main goal, gravity will do the rest!

- One experiment sometimes quoted is drawing a circle,
- and then taking a number of sticks of the radius
- of the circle and dropping them.
- As you increase the number of sticks, the chances
- of one of them crossing the circle increases, but
- not linearly. The probability of a single stick
- crossing is related to Pi (but I can't remember how
- exactly).

Dropping all the sticks at once? Or clearing the board and dropping them one at a time? In that if all at once, there would be interaction between the sticks that might force out out of the picture on the way to the target.. Which is true for my penny at he wall scenario, but not true for bullets that don't all leave the barrel at the same time.

- Yes, but it can be a smaller increase than you seem
- to think it is.

NO IT IS NOT! I don't assumed a doubling effect, never did, not even before I spoke with you.

- To know exactly, I'd need to look
- at Ogre's figures and do the calculations. If anyone
- has any links to his site it would help. Or
- alternatively
- a link showing dispersion for .50 and 20mm guns at
- air-to-air ranges. Then I could write a simple
- program and get some real numbers.

Well, write it in C/C++ so when you present it I can double check your work... That or MatLab! Stay away from MathCad.. pretty GUI and all, but I like code! /i/smilies/16x16_smiley-wink.gif

- That's not my intention.

Ok.

- it's an analogy only!!!!!

And a bad one! /i/smilies/16x16_smiley-wink.gif

- I have a cat. I could borrow the neighbours dog :-)

LOL! Well video tape it, because it would be a hoot! /i/smilies/16x16_smiley-happy.gif

- I know. I said this. I just couldn't think of a
- better analogy at the time!

Roger, Ok, I understand, I do the same thing sometimes, over simplify in the hopes of everyone getting something out of it, then there is Allways some S head that stands up and say how stupid you are for using such a bad example.... Hey... wait... Does that mean I'm the S head?

- I'll see if I can get hold of some disperion figures
- and knock up a program (I'll publish the source)
- to show the differing chances of hitting (assuming
- that you are aiming on or close to the target -
- that one is hard to compute for all the
- possibilities air-to-air) and run some
- simulations. That might be a bit fairer.

But... it sounds like the hardest part is still left out.. GETTING ON TARGET IN THE FIST PLACE... Or will this factor that in somehow?

- I'm not stating a number either - I've just been
- tryinig to illustrate things with examples.

Roger!

- The Hispano V doesn't weigh a great deal more than
- a .50. 4 Hispano Vs weigh less than 8 .50s.

Well, pick the two extremes and leave out the FACT that the ammo weight more!

- True for the USSR too.

They all got better at it... Had to, in that better bombers kept coming out! /i/smilies/16x16_smiley-wink.gif

- yep - took that into account too, as best I could
- (only knowing the diameter of the rounds rather
- than the catridges meant I had to estimate a bit,
- assuming the catridge diameter scaled up similarly).

Hmmmmm well, depends, I have seen some cartridges very greatly.. I actually forgot about that.

-
-- You missed my point, not talking time, I'm talking
-- spare ammo to take a few practace shots...
-
- If you have the same firing time, then you have
- the same ability to take practice shots - i.e. you
- total firing time is depleted equally in both
- instances.

Ok, so if you want to have the guy with the 20s waste ammo walking it on, you have now reduced the number of times he can do it.

- Not if you have the same firing time!

For once instance! I state it again, with more ammo, you can have worse aim, in that you can walk the rounds onto the target. Now with less ammo, it forces you to be a better shot, assuring you want to get the same number of kills.. -OR- you can walk your ammo onto a target too... but sense you don't have as much ammo, you wont be able to do the walk as many times, i.e. you won

-- Try 4 to 6! Still in the linear range, or plato yet?
-
- It's not linear at any point.

Ah, ok, I based that comment where you said it was pretty linear between... was it 2 and 4 coins? thus my question from 4 to 6.

- It was an example of the diminishing returns from
- repeated samples only.

Well, still not totally sold, I'm not even sure it is good for modeling diminishing returns... My gut says it will be diminishing, but I don't think the coin toss model is good. For example, the coin toss does NOT take into account the ROF spacing. You know that space between rounds doing down range we talked about... for a fixed rate of fire, the more guns the spacing gets smaller, thus less chance of the target slipping threw, thus a better chance of a HIT! Now before you point out that .50s don't fire evenly, I know, but if you take the average of one firing slower than evenly (bigger gap) and another firing faster then evenly (smaller gap) it would probably work out to be equal to assuming they are firing evenly.

-- DING DING DING!!!! EXACTALLY!!! That variable is not
-- captured by the coin toss,
-
- No, it isn't.

So, you agree, coin toss is worthless for talking about hits,kill

-- and I think you would
-- even agree that those gaps get smaller with more
-- guns firing down range!
-
- Totally. But about a certain ROF, this stops
- making a difference, like trying to dodge raindrops.
- Above 900rpm in the full deflection example you
- can't avoid being hit. There are other scenarios,
- but by the time you get to 4 20mm cannon, it's
- basically impossible to avoid at least one hit
- if you fly the plane through the stream of rounds.

Agreed.. but again, your assuming your INITIAL AIM IS ON!! That little assumption was the hardest part of air to air back then! To assuming even firing times, passing threw all stems from assuring your aim is on at the FIRST PULL OF THE TRIGGER!!! It typically wasn't!! Check out the old gun camera stuff, just about every one I have seen shows the pilot WALKING THE TRACERS ONTO THE TARGET!!

- The question is spray-and-pray the best tactic,
- a valid tactic, worthwhile having the option of?
- I don't know the answer to that one.

It wouldn't be if you knew your pilots all had near perfect aim... But, they knew they didn't, Thus, Once again, a smart move by the USA.

- I meant that there are difference chances to
- 'slip between the rounds' depending on the relative
- maneouvering of the aircraft and their relative
- orientations. For a 300ph basic full deflection shot
- against a fighter, 900rpm will ensure at least 1
- hit.
- With an engagement with wing mounted guns, not at
- convergence, with high relative roll, you need much
- more ROF to be sure of at least one hit. (Note this
- is about 900rpm combined from all guns).

And stars off assuming the aim is on... Which in fact it hardly ever was! And the gun camera stuff agrees with that.

- Yes, and that is what a pilot should do -
- anticipate.

LOL! Should and Could... Two of MAN's biggest battles sense the begging of time... and probably till the end of time.. or MAN!

- Since there is a delay in the guns firing, and
- the target would be across your sights for about
- 1/10 seond then prefiring would be a good idea
- anyway.

If you saw it coming, which, in your scenario, i.e. broad side, you probably wouldn't have picked it up in your perfial vision in time.

- Most aircraft guns are mounted across the width
- of the plane. If the target flies in at 45 degrees
- then the effective time in front of a gun is
- reduced.

Assuming the aircraft doing the firing does not TRACK it! Which is hardly ever the case!

- Thus you need a higher ROF to ensure at least one
- hit from that gun. Since you can't be sure how
- the guns are synchronised to each other, you can't
- otherwise be sure that each gun might not miss
- in turn.

Nice thing about not being synchronised is you could also obtain all 6 firing at once! Thus a wash in statistics, wouldn't you agree? /i/smilies/16x16_smiley-wink.gif

- I.e. to be totally sure of a hit you need
- to ensure that each gun can put out enough rounds
- to be sure of hitting the plane on its own.

I don't buy it, in that it would change for every situation! So no mater what you pick for ROF, you could come up with an angle where it would be good.. Any ROF within reason of WWII type MG, not modern chain gun stuff!

- To have a good chance of hitting the plane, we are
- back to the diminishing returns thing again.

Are we? <G>

- That's got nothing to do with this part of the
- argument.

Roger, re-read it, your right! Thought you were talking destruction power, your talking gaps between rounds.

- You have a line that as you decrease the ROF drops
- non linearly, but steadily, until it hits the
- critical

Ok, so far so good.

- ROF, at which point it decays rapidly, and then
- tails off. Like a culmulative score graph (ogive).

So like a discharge of a cap..

-- Never said it wasn't, just noting that more complex
-- system means more chance of failer.
-
- That it does.

Something the Lw types Allways seem to convently forget when talking about HE rounds! /i/smilies/16x16_smiley-wink.gif There were storys of planes landing at base with a 20mm HE stuck in the side of the AC.

-- Hmmmm area/mass... hmmmmmm area, a squared term,
-- mass would be tied into the volume.. a cubed term...
-- hmmmm Ill have to give that a little more thought..
-
- It's also why, all other things being equal, a heavy
- plane can accelerate faster in a dive.

Agreed.

- The mass increases as the cube of the dimension,

Agreed

- all other things being equal. But the 20mm round
- is about half as long as you'd expect from a scaled
- up .50 round. Plus it is not a solid projectile.

True.

- It has less mass than you'd expect, relative to its
- surface area, than you would from simply scaling
- the dimensions by 20:12.7. If the surface area
- (and we assume drag does too, for a first
- approximation)
- scales with the square of the dimension, and the
- mass with the cube, then the ratio of mass:surface
- area (and thus kinetic energy:drag) should increase
- linearly with dimension. But perhaps with the 20mm
- round we have some fraction of the mass we'd expect.
- If we have less than 63% of the mass we'd expect
- from
- just scaling up a .50 round, then the 20mm round
- has more drag per unit kinetic energy.

All in all, not good to have a short cannon round, when one of the benefits is mass.


TAGERT
-------------------------------------------------------------------------------------------------------
If WAR was not the ANSWER.. Than what the H was your QUESTION?

XyZspineZyX
06-27-2003, 08:39 AM
Hey Milo,

You dont have to believe me but like I said--there is actual gun camara footage of P47's "lighting up" Tiger Tanks by ricocheting bullets from the rear of the tank.

Tune into the Discovery Channel and see it for yourself.



Milo wrote----It would be nice if this myth of shooting through the thin bottom of a Tiger would die. The bottom of a Tiger was 25mm or 1" thick or at a richochet angle thickness of ~ 100mm or 4".


Sorry bud but it aint No Myth !

XyZspineZyX
06-27-2003, 08:42 AM
Actually, I'm totally convinced that the 50's in FB are modeled accurately enough as to real life. Here is the test:

In real life, there were over 100 US ace in a day, ie 5 kills/sortie loadout. Generally, in P51's, some P47's, as well Hellcat and Corsairs.

In the ETO, you see a number of 5kill/sorties vs Me109's and FW 190's.

All you need to do convince yourself of this, is setup an offline Quick Combat with 2 wing of 4 of each on YOUR side, set to novie and empty.

Then go shoot them down. I can easily down 7-8 Me109's and 5-6 Fw190's in a P40, or P47.

Now the 109's you can get from the straight 6 decent enough, but not the 190's due to the armour. In either case, especially the 190's, you need about 15 degree offsets to the either side or above. This is sufficient to take of wings, break fuses, or if you hold the fire long enough, explosions.

To me, this comparitive ability to shoot down 190's and 109s with the .50 cal P47 and P40 is so close to actual... I don't see where it can be improved (speaking of 50cal ability to inflict damage divided by 109/190 DM).

" The first time I ever saw a jet, I shot it down ": General Chuck Yeager, USAF, describing his first confrontation with a Me262 - - -
" Aggressiveness was a fundamental to success in air-to-air combat and if you ever caught a fighter pilot in a defensive mood you had him licked before you started shooting ": Captain David McCampbell, USN, leading U.S. Navy ace in W.W.II.

XyZspineZyX
06-27-2003, 12:35 PM
Sorry, it is a myth, no Tigers were found to have been knocked out because of ricocheting bullets to its >>belly<<. In fact the number of tanks knocked out from the air is over-claimed by a large factor.

I have seen that footage but would not say they were Tigers. But then all German tanks were Tigers, were they not, to GIs./i/smilies/16x16_smiley-wink.gif

Think Kahuna. What angle would the a/c have to dive at? What would happen to the shape of the bullet after ricocheting of the macadam or cobble stones? The shallower the angle the thicker the armour gets. What would be the velocity of the bullet be after hitting the ground - did it increase or decrease?

If you want to believe the almighty American .5" was that good, well then there is no hope for you.


BigKahuna_GS wrote:
- Hey Milo,
-
- You dont have to believe me but like I said--there
- is actual gun camara footage of P47's "lighting up"
- Tiger Tanks by ricocheting bullets from the rear of
- the tank.
-
- Tune into the Discovery Channel and see it for
- yourself.
-
-
-
- Milo wrote----It would be nice if this myth of
- shooting through the thin bottom of a Tiger would
- die. The bottom of a Tiger was 25mm or 1" thick or
- at a richochet angle thickness of ~ 100mm or 4".
-
-
- Sorry bud but it aint No Myth !
-



http://www.wpafb.af.mil/museum/air_power/ap18a.jpg

XyZspineZyX
06-27-2003, 12:40 PM
A most recent research from N. Zetterling shows that only around 2% of the German AFV losses were directly realted to Allid Airpower in Normandy.

Interestingly enough, this 2% is the same as the hit rate of Typhoon rockets at a tank sized targets (according to a British test).




http://www.x-plane.org/users/isegrim/FB-desktopweb.jpg
'Only a dead Indianer is a good Indianer!'

Vezérünk a Bátorság, K*sérµnk a Szerencse!
(Courage leads, Luck escorts us! - Historical motto of the 101st Puma Fighter Regiment)

Flight tests and other aviation data: http://www.pbase.com/isegrim

XyZspineZyX
06-27-2003, 01:17 PM
Interesting test carried out during the Korean war:

For those uninitiated in the Korean War arguments over the difference between .50 caliber ammo the B-26s/F-84s used and the 20mm HEI that the Marines used, they scheduled a test in Taegu in the summer of 1951 between USAF F80 Shooting Star and F-84 Thunderjets with 30 rounds of 50 caliber per gun. The Marine F4U-5N had only 10 rounds of 20mm HEI. The F4U-5N was flown by Lt. Roland of the VMF(N)-513. USAF aircraft attacked their truck carrier targets with .50 caliber and caused the max damage of a "the kapok seat of one carrier began to smolder." The F4U-5N snapped the frame of the truck almost in half; blew one of the front wheels off; and destroyed the flatbed. On his second run, he hit the cab and snapped the steering column in half. Despite these tests, the USAF persisted in the use of .50 caliber ammo simply because there was a lot of it left over from World War II. Even today many people feel the USAF MiG kills would have been much higher if they had used 20mm HEI instead of .50 caliber as Soviet jets were literally riddled with holes from .50 caliber...but continued to fly and returned to base.

http://www.kalaniosullivan.com/KunsanAB/VMF513/Howitwasa1ac.html

XyZspineZyX
06-27-2003, 02:24 PM
Comparing the P-40s guns to the P-47s guns makes me revise my earlier statement..... there may just actually be some undermodeling of the 47s guns...Gibbage explains it better than i can in a thread in the GD......

<CENTER>http://www.world-wide-net.com/tuskegeeairmen/ta-1943.jpg <marquee><FONT COLOR="RED"><FONT SIZE="+1">"Straighten up.......Fly right..~S~"<FONT SIZE> </marquee> http://www.geocities.com/rt_bearcat

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<Center><div style="width:200;color:red;font-size:18pt;filter:shadow Blur[color=red,strength=8)">99th Pursuit Squadron

XyZspineZyX
06-27-2003, 03:18 PM
tagert wrote:
- Aaron GT wrote:
--- No, you have to remember that the de fence of the UK
--- was left upto the RAF!
--
-- I was talking about the threat of attack of US
-- assets outside the USA, specifically the Philipines.
--
-- In Europe, the USA had troops in Africa, Italy, and
-- France, that all, at various points, would need
-- protection from bombers.
-
---SEE HERE--
- Ah, I see the misunderstanding here. You are
- operating under the impression that NATIONS main
- purpose for building ARMYS is to protect ARMY'S
- ASSETS, Where as I'm operating under the impression
- that NATIONS main purpose for building ARMYS is to
- protect NATIONS!

That's a side issue. I am talking about what the
planes were used for.

In terms of design, a lot of weapons are built
with the requirement to be able to defend military
or colonial assets in addition to the home nation.
Certainly in the 1920s and 1930s the British designed
planes specifically for overseas operations, and not
defence of the home country. The USA also had an
eye on its ability to wage war overseas (it did
a fair bit of it in the first part of the 20th
century) and protecting its assets abroad (Philipines,
Hawaii, Alaska).

- You have to understand two things
- for this to really make sense.. One in the 20,30,40
- the USA had a very isolation attitude towards Europe
- and all their problems.

It also had military establishments in the Philipines,
Hawaii, Alska, Nicaragua, Honduras, Costa Rica, etc.

- TWO Americans, American
- government didn't then, and until 911 didn't give a
- RATS A** about A**ETS outside of the USA!

See above. It did give a proverbial monkey's about
its own assets already in those parts outside the USA.

- Recent
- History proof, We didn't give a RATS A** when Bin
- Ladin bleu up that US Embcy..

Well apart from the series of missile strikes that
followed it...

-- Apart from Italy and North Africa...
-
- SEE ABOVE, where it says --SEE HERE--

I did. You are wrong.

-- What I was saying was that the threat from light
-- bombers was as real as from heavy bombers.
-
- Not to the lower 48.

There was little threat to the lower 48 states
from the main threats (Japan or Germany) from either
light OR heavy bombers. The threat was as real, i.e.
small. In fact given the ranges, the threat from
long range heavy bombers was actually greater than
that from light bombers as light bombers generally
have much shorter range.

-- The safety was in the relative distance of the
-- continental USA from threats.
-
- DING DING DING... which is also why the whole
- isolation stance work pre 1950s+

It was isolationism with respect to Europe, rather
than isolationism in a total sense, as there were
a number of military interventions in this period,
plus owning of assets outside the continental USA
(notably Alaska, Hawaii, Philipines). More or less a
statement of the Monroe doctrine.

-- I was trying to demonstrate the PRINCIPLE, not use
-- exact numbers.
-
- Should note that than when doing so.

I thought what I was doing was clear, but maybe you
are right and I should have been clearer.

-- The RAF found the critical problem in the Battle of
-- Britain was loss of pilots. Thus killing a pilot
-- was in a sense more important a task for the LW than
-- destroying the planes.
-
- We didn't face the RAF, they were on our side.

But you'd think that reducing the number of LW
pilots would be of interest, surely?

- Your still missing the point, you have to hit it
- first!

Yes, and that would not be a particular problem
with 2 20mm cannon. I've nearly finished by
program which will demonstrate this. I just
need some realistic figures for dispersion from
20mm cannon and .50 MGs.

- And with more guns you have a better chance.

Yes, but not nearly the increase you seem to think
it would be.


- Agreed... ONCE YOU ARE ON TARGET AND GETTING HITS!!

Ok... if I have 4 20mm cannon with 200 rounds,
and 8 .50s with 400 rounds (ROFs are about the same)
in what way do I have ammunition to waste with the
.50 that I don't have to waste with the 20mm cannon?
In fact given that I may have to fire for a longer
time when on target with the .50s I might have LESS
firing time to range in with .50s than with the
20mm cannon.

If you look at the lift capacity of the P47 then
replacing 8 .50s with 4 20mm cannon would give
you rather comparable firing times. Ditto if
you replaces the 4 .50s in the P51B with 2 20mm
cannon.

- And that is another one of my points you keep side
- stepping...

No, I am not side stepping it, I just don't understand
what you are talking about.

- With more guns, you get more ammo down
- range, thus more chance of a hit,

Not such an increased chance of a hit as you think.

- with smaller guns
- (i.e. not cannons) you can carry more ammo.

But you may have exactly the same firing time!

- Thus you
- have ammo to play with, by play with I mean you
- don't have to have PERFECT AIM!!!

If you need 1/10 of a 4 20mm cannon load (say 40
rounds in the example above) to down a plane, then
given that the USN felt that one 20mm round was
worth 3 .50 rounds, you'd need to fire 120 .50
rounds. You have more guns, but in fact you need
to fire a longer burst. So with equal firing time
with 20mm cannon you might have more ammunition
you can afford to waste and still put a target
down

This assumes the same chance of hitting
per gun (which will be true if the ballistics are
the same - note this is per gun, not the overall
chance of at least one hit).

- You could WALK THE
- ROUNDS ONTO TARGET!! Where as with bigger guns, and
- less ammo,

Less ammo doesn't matter if the firing time is
more or less the same (provided you keep up some
decent level of ROF of course - I am not talking
about taking things to absurdity and one round
a minute!)

- Yet they never did it.. That and even the NAVY who
- installed them into F4us didn't continue with it.

I was under the impression that they did. They
certainly seemed to use a lot of 20mm cannon in Korea,
and the USAF also swapped to 20mm cannon then too.

-- This was the line taken by other nations, in using
-- cannon armament, even those not facing heavy
-- bombers.
-
- Name one that didn't!

USSR, UK, France (e.g. Dewotine D.520, the last and best
French fighter before it was overrun).

- All nations in WWII city faced
- attackers from bombers,

Bombers, yes, heavy bombers, not really. The Germans
had very few.

-- The RAF ALSO didn't encounter heavy bombers,
-- yet felt 20mm cannon worth while enough to use them
-- as the primary armament on most fighter aircraft.
-
- Heavy, Medium, Light... NONE could get to the USA in
- any useful manor!

Actually towards the end of the war the Germans
did build a bomber capable of getting there, but
it wasn't produced, it was just a prototype. It did
have some long range recce bombers (JU290, Condor,
but they didn't really have the range either)

- When your factory, an ASSET is 5
- miles from the border of a country you going to war
- with... YOU BEST BE DAM WORRIED ABOUT DROPPING ASAP!

Well of course.

-- Not significantly greater, though. The returns on
-- increasing number of guns is diminishing.
-
- But better none the less!

Yes, better. Good enough to warrant the extra
weight? Very debatable. Check out Tony Williams' site.

- And the gun count never
- reach a point of diminishing returns on USAAF
- aircraft.

Many people would disagree with this in terms
of the likelihood of at least one hit.

You would be correct to say that tne expected
number of hits E(hits) increases with the number
of guns, but this is not the same as P(hits>1).

-- The Hispano II has the same muzzle velocity, and
-- a much heavier round. It has more kinetic energy
-- per round.
-
- Yet we didn't use it.. That says a lot for the .50s.

The USA used it on the P38, A20G, P61, F4U, F8F, F7F,
A1.

- Like I keep saying, your assuming you have the aim
- to get the hits..
thus you are ignoring the hardest
- part! GETTING THE AIM TO GET THE HITS!!

Yes, because that is to do with the pilot, not the guns,
so isn't a useful part of this discussion.

- And, as I
- noted, smaller mg like the .50s with more ammo means
- you don't have to be as good of a shot,

Well I am trying to point out that this is not
a good argument when talking about the .50 and
20mm cannon, as you can have the same (or more)
hitting power with equal firing time in the same
airframe.

- simple pull
- the trigger, and WALK THE ROUNDS ONTO THE AIRCRAFT!
- Cant do that, or at least can do it as many times in
- a ship with large guns and small ammo counts..

You are obsessed with ammo counts! You need to
think about firing times.

- Agreed 100% something I have point out with regards
- to Williams sight and his fancy full "what if"
- scenario where he put together the dream machine of
- fighters. Totally disregards the facts of war in
- WWII.

He knows what he is talking about with respect to
armaments, and I think he's allowed a little
recreational flight of fancy!

- But, when faced with something that is
- BROKE!!!! WE FIXED IT!!! For example, did we stick
- with the Allison in the P51 after the Brits pulled
- our heads out for us and showed us the Merlin...

The history of WW2 is littered with instances when
one problem was fixed, but in another case a change
might have been beneficial, it was not taken. Let's
not assume some sort of inability not to mess things
up. All bureacratic structures do that. I know the
British did many times, and followed all sorts of
dead ends. For example the Westland Whirlwind could
have been an excellent fighter with the right engines,
but it didn't happen. Or look at the whole disaster
with certain parts of the LW blocking the development
of the He219, delays with the Me262, etc, etc.

-- So perfect the USN wanted cannon :-)
-
- So perfect were they that they stopped using them

The US military was being wound down at that point.
For example, on that basis, the P47 couldn't have
been very effective, as the line was canned, and the
planes sold off or scrapped. I don't think you can
read much into the cost saving actions after a world
war when the priority is to get 9 million people
out of uniform and get the civilian economy working.

- was devoted to ground attack roles... If you think a
- bomber is easy to draw a bead on, try a truck!

As mentioned here, they tested on trucks...


--- Disagree.
--
-- Actually I was being pro .50 at this point.
-
- Disagree

Ok - have it your way.

- CHA CHING! Yet.. you think a coin toss statistics
- model with fit?

No - and I said it didn't! I said it was an analogy
to demonstrate the diminishing returns and nothing else.

-- US Army decided to create volume production based on a
-- tried and tested design, relying on numbers to win
-- out.
-
- Your point?

My point is that it was an adequate weapon, produced
to allow for rapid expansion in the forces. It was
not the best weapon possible, and others possibly
could have been available, but the decision was to
produce it to allow for expansion.

My supplementary point is that not saddled with
these concerns, we have the ability to ask 'was
the .50 the best performing gun, or, if 20mm
cannon had been used in the P47 (or whatever) would
it have performed better'. It's a 'what if'.

- And your.. i.e. THAT argument would be true for the
- Allison Engine...

Well no, in that the USAAF wanted a long range
high altitude escort plane that would perform
better than the P38. This wasn't possible with the
Allison engine, and the options were more work
on the P38, or using P51 with the Merlin that
seemed to have the required performance.

- Only more efficient once you start getting hits.

Yes... I know... Wait until the results of my
simulations, then. The code is almost written. I
just need to find the dispersion figures, and then
refresh my memory of black-and-white bitmap file
formats so I can draw in some plane profiles.


- True, them Brits did like the mix, cannons for
- bombers, Mg for fighters

I have no idea what you are talking about here.
The standard basis for RAF armament was 4 20mm cannon
for most planes. This included those originally
intended to be interceptors (The Typhoon was intended
to have this role) againdt both fighters and bombers.
Some aircraft (e.q. Mosquito) gained additional MGs
in addition. In the case of the Spitfire the 4 20mm
cannon wing was used in some instances, but the primary
armament was 2 20mm guns plus MGs as the thin wing
of the Spitfire was seen as a problem.

The RAF used cannons for attacks on fighters and
bombers, sometimes MGs added into the mix because
there was space (Mosquito) or not seen to be enough
space (Spitfire). Where new designs were made
(Typhoon, Whirlwind) 4 20mm cannon were specified,
with no MGs. (The Typhoon 1a was a stopgap produced
in very small numbers).

- Something I have been saying from the get go.. If
- you think .50s were good in the air, they were even
- better on the gnd targets!

See other posts.

-
---- In 1940-41, yes, but apart from the Beidecke Blitz
---- of 1942, it wasn't a requirement from 1943 onwards,
---
--- Not True.
--
-- Actually it is entirely true. Britain faced very
-- little bombing by Germany after the Beidecke Blitz.
-- I can dig up the figures on sortie per year if you like.
-
- Ah, I see your mistake, your statement says it after
- the fact...

I was pointing out the historical fact.

Actually from 1943 onwards there was always the chance
of heavy bomber attacks, although the feeling was
(read what was said at conferences) that Germany was
beaten.

- Which is easy, but at the time they
- didn't know for sure. Kind of like we didn't expect
- the battle of the budge.

Not really very comparable in nature.

I take your point in part, though.

-- My point was more that the RAF had swapped to an
-- offensive role over Europe before Overlord. There
-- were few raids by German bombers of any size or
-- real intent to deal with.
-
- Again, knowledge after the fact...

Huh? It had already switched to the offensive. This
is just plain historical fact!

- Allways can be
- used to make people look stupid. Hind sight is 20,
- 20.. The fact is the possibility of a bombing raid
- was there.

In theory, but the chances of the LW pulling its
comparatively short range bombers from tactical
support on the Eastern Front after Stalingrad was
basically zero, The threat was from some other form
of attack (V1, V2, or nuclear). If the attack had
been nuclear, then it would have been launched at
night, in which case RAF defences would have been
fairly ineffective given the difficulty (even with
advances in radar) of attacking the bomber(s).
Night intruders continued to shoot down aircraft
over RAF bases into 1945 as they operated at low
level in small numbers. This would probably have been the
delivery mode for a nuclear weapon for LW if
a V2 could not have done the job.

-- A few tens.
-
- Ah! Well, true of one cannon.

?? The muzzle velocity is the same no matter how
many cannon there are.

- Is what I'm saying, but, you missed the point. Point
- being when something didn't work, logistics,
- production, experience or not, we changed it to fix
- it!

Agreed. And I agree that the USAAF felt that changing
fighter armament on existing types wasn't, on the whole,
of sufficient


- A bad demo imho!

If you say so. It demonstrated, easily, one of the
things I was trying to get across. I've now got
something rather closer to reality in preparation.

- LOL! I like it, sounds like it would account for
- that initial aim of a cannon driver.. But to
- simulate the .50s driver you would have to let him
- role the dice more than once,

Why? He doesn't have the ability to aim the plane
in two different directions. The chance to hit
given a good aim (the coin flipping) encompases
the effect of additional guns.


- And we haven't even begun to model the aim of the
- pilot,

The roll of the dice does that.

- they are just assuming the same aim and
- unlimited ammo.

The type of gun shouldn't affect the skill of the
pilot in bringing them to bear (assuming that the
ballistic properties are broadly similar), hence
there is no reason to make this different for each
weapon type.

In the progrsm I am writing, though, I simulate
a random aiming point within the general area
of the aircraft, and then movement of the aim
to simulate relative movement of the aircraft.


-- The dice term above is dependent on what the chance
-- of getting a suitable firing solution were for a
-- pilot in WW2 (rather harder to compute).
-
- LOL! My joke was not that far off.. Ok, now let the
- .50 drivers roll the dice more than the cannon
- drivers, and we have a pretty good model!

The coin flipping represents the number of guns.
The initial dice roll represents the aim. The
.50 armed plane cannot aim twice, it just has
more guns. Multiple dice rolling would work if
we were talking about B17 turrets, where the
aiming is more indepdendent.

-- And you'll find that if you do this then increasing
-- the number of coins has a lesser effect on your
-- chance of one hitting the spot than you think.
-
- Nope! In that I don't think it would be a linear
- improvement, but I KNOW IT WOULD BE BETTER NONE THE
- LESS!!!!

Wait for the computer simulation results. I'll post
the source code so people can comment on it, so everything
will be totally open.


- Dropping all the sticks at once? Or clearing the
- board and dropping them one at a time?

As long as they don't clang into each in mid
air it doesn't matter,


- Well, write it in C/C++ so when you present it I can
- double check your work...

That's the idea. I was going to write it in C++,
but then wondered if C might be easier as more
people might have C compilers (or maybe I should
have done it in Java, but it's mostly done now
so I am not going to change it to Java now).

- LOL! Well video tape it, because it would be a hoot!

Thing is our cats love the neighbours dog so it
would be pretty static and not a good test!

- Roger, Ok, I understand, I do the same thing
- sometimes, over simplify in the hopes of everyone
- getting something out of it, then there is Allways
- some S head that stands up and say how stupid you
- are for using such a bad example.... Hey... wait...
- Does that mean I'm the S head?

I won't comment!

I am a physicist at heart, and take the words
of Occam and Einstein to heart - make things
as complex as they need to be and no more. That
means starting with first approximations. Plus
simple cases are sometimes better for getting
across parts of the whole picture, even if they
don't hope or intend to address the whole picture.

- But... it sounds like the hardest part is still left
- out.. GETTING ON TARGET IN THE FIST PLACE... Or will
- this factor that in somehow?

I am assuming that the pilot opens fire by
randomly spawning an aim point withiin the general
vicinity of the target (controlled by an aim quality
paramter on the command line). The aim point then
moves in a random direction by a specified amount
per second to simulate relative target movement.

A bullet firing event then occurs in which N
bullets are fired (one for each gun). For the
moment I've assumed all guns are centred on
the point of aim, and are coaxial. I'll add in
wing mounts and convergence later. Each bullet
has dispersion in a random direction applied, and
then the hit/miss status is calculated.

The aircraft is created by using a black and
white silloutte in a black and white bitmap
of 512x512 where each pixel represents a 10cmx10cm
area. (I'm hoping to use 3 view plans and scale
and paint them for various aircraft types, basically).

Thus gives a 51.2x51.2 m area, which is big enough
to cope with bombers too. If the resolution isn't
fine enough I'll change it.

-- The Hispano V doesn't weigh a great deal more than
-- a .50. 4 Hispano Vs weigh less than 8 .50s.
-
- Well, pick the two extremes and leave out the FACT
- that the ammo weight more!

The ammunition does weigh more, but with less
guns you need less of it. You also, within the
weight limit of the original installation, get
to use the weight of the no longer present .50s.

- Hmmmmm well, depends, I have seen some cartridges
- very greatly.. I actually forgot about that.

Yep. It was just an estimate I did. A fairly reasonable
ball park figure.

-
--
--- You missed my point, not talking time, I'm talking
--- spare ammo to take a few practace shots...
--
-- If you have the same firing time, then you have
-- the same ability to take practice shots - i.e. you
-- total firing time is depleted equally in both
-- instances.
-
- Ok, so if you want to have the guy with the 20s
- waste ammo walking it on, you have now reduced the
- number of times he can do it.

No. I don't know how you conclude this.

- For once instance! I state it again, with more ammo,
- you can have worse aim,

If the firing time is the same then this is not
the case.

- Ah, ok, I based that comment where you said it was
- pretty linear between... was it 2 and 4 coins? thus
- my question from 4 to 6.

If I implied that, I didn't mean to. It's not linear
at any point. What I probably did or meant to say
was that the returns diminish more rapidly between
4 and 6 than between 2 and 4.


- So, you agree, coin toss is worthless for talking
- about hits,kill

It's only a first approximation, as a tool for discussing
diminishing returns. As to whether it is worthless, that
depends on a value judgement on how closely you require
the model to model the real data.

- Agreed.. but again, your assuming your INITIAL AIM
- IS ON!!

Well if the pilot is firing into empty space it doesn't
matter where they are firing.

By 'on' I am assuming that the aim is at least in the
same general part of space as the target.

- That little assumption was the hardest part
- of air to air back then! To assuming even firing
- times, passing threw all stems from assuring your
- aim is on at the FIRST PULL OF THE TRIGGER!!! It
- typically wasn't!! Check out the old gun camera
- stuff, just about every one I have seen shows the
- pilot WALKING THE TRACERS ONTO THE TARGET!!

Which they did quite happily with 20mm cannon too.

In the Tempest the firing time was typically about
15 seconds. Dittor the Spitfire I in the Battle
of Britain. They walked fire with both if necessary.
The firing time was the same.

With a 4 20mm cannon set up, the firing time would
likely (if fully loaded) be the same as 8 .50s. Thus
you have the same amount of firing time to walk
the fire onto the target.

[.. snip...]

- If you saw it coming, which, in your scenario, i.e.
- broad side, you probably wouldn't have picked it up
- in your perfial vision in time.

In which case, given the speed of the target, and
himan reaction time, electrical firing delays, etc.
you'd miss the target anyway.

- Assuming the aircraft doing the firing does not
- TRACK it! Which is hardly ever the case!

true - and something I haven't built into my
program yet, but I'll do that in version 2.

- Nice thing about not being synchronised is you could
- also obtain all 6 firing at once! Thus a wash in
- statistics, wouldn't you agree?

There is an element of that, and something to
simulate as I work on the program.

-- I.e. to be totally sure of a hit you need
-- to ensure that each gun can put out enough rounds
-- to be sure of hitting the plane on its own.
-
- I don't buy it, in that it would change for every
- situation!

Exactly.

- So no mater what you pick for ROF, you
- could come up with an angle where it would be good..

Or bad.

- Roger, re-read it, your right! Thought you were
- talking destruction power, your talking gaps between
- rounds.

yep.

- So like a discharge of a cap..

In reverse, yes.

- Something the Lw types Allways seem to convently
- forget when talking about HE rounds! /i/smilies/16x16_smiley-wink.gif There were storys of planes
- landing at base with a 20mm HE stuck in the side of
- the AC.

Ditto .50 rounds!

- All in all, not good to have a short cannon round,
- when one of the benefits is mass.

Yep. But then there are all those other compromises -
you don't want a round that is so heavy that you
can't build a gun light enough to fire it to fit
in a plane!

XyZspineZyX
06-27-2003, 03:25 PM
Bearcat99 wrote:
- Comparing the P-40s guns to the P-47s guns makes me
- revise my earlier statement..... there may just
- actually be some undermodeling of the 47s
- guns...Gibbage explains it better than i can in a
- thread in the GD......

It's probably the dispersion rather than the guns.
I can't see that there would be two different
forms of .50 in there (unless one was some sort
of accidental development version which the P47
still references?)

XyZspineZyX
06-27-2003, 06:15 PM
Did some testing and indeed it seems that the P-47´s 0.50 cal configuration displays some relatively high bullet dispersion as compared to other .50 cal equipped aircraft. While it didn´t became obvious when going after large targets such as bombers, against nimble fighters at 200m+ it´s quite noticeable, especially as IL-2/FB features no hitboxes extending beyond the actual 3D model, so a few cm do make the difference between hit and miss. Speculation whether the dispersion is intentional due to a design decision; i.e. using pattern- instead of point harmonization for the P-47, or due to physical attributes of the ingame P-47, which i think is rather likely. What did work satisfactory as a countermeassure was to set the gun convergence considerably lower, i.e. 100m. The P-40M on the other hand displays alot less dispersion even at high convergence settings, and generally scores more hits on small targets because of this. In a QMB fight against ME-109 G-6 A/S a burst of 2 seconds from a 180? aspect angle was usually enough to either explode the Messerschmitt directly, or to cause sufficent damage to practically disable it with the pilot bailing out.



============================
When it comes to testing new aircraft or determining maximum performance, pilots like to talk about "pushing the envelope." They're talking about a two dimensional model: the bottom is zero altitude, the ground; the left is zero speed; the top is max altitude; and the right, maximum velocity, of course. So, the pilots are pushing that upper-right-hand corner of the envelope. What everybody tries not to dwell on is that that's where the postage gets canceled, too.

XyZspineZyX
06-27-2003, 07:13 PM
Oak_Groove wrote:
- Did some testing and indeed it seems that the P-47´s
- 0.50 cal configuration displays some relatively high
- bullet dispersion as compared to other .50 cal
- equipped aircraft.

I wonder... Could it be the .50 gun model is the same for the P40 and P47, and that .50 modeled fine/well with regards to the kill power.

But, maybe the vibrations due to one .50 is over modeled and thus playing to big of a factor with regards to the dispertion?

In that would account for the difference seen going from 4x.50s on the P40 to 8x.50s on the P47.

In that I personally belive the vibration of the aircraft due to .50s is over modeled. Dont get me wrong, I know the pilot would feel the vibrations, and should feel more of them in a P47.. but the effect they would have on the aircraft as a whole.. I just dont think it would move the AC as much as it appears to move in the game. I base that *feeling* on what COL Kit Carson had to say with regards to the P51D and it's guns. He pretty much debunks the whole aircraft loosing tens of miles per hour by firring the guns.



TAGERT
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XyZspineZyX
06-27-2003, 09:59 PM
I tried just firing the inboard guns (1+2) of the P-47, while slowing the gamespeed down to 1/4, to get better visual feedback on the amount and pattern of dispersion. This brought it down to 4 .50 machineguns firing as opposed to 6 on the P-40M used as reference. From what i´ve seen there are no obvious differences in 4 or 8 guns firing, the P-40 does appear to have tighter groupings with 6 guns than the P-47 with 4. If you compare the structures and wing mounted armament installations of the P-40 and P-47, you´ll note that the P-47´s guns are located much further away from the aircrafts center of gravity, which in real life could, and probably did, cause problems if there is a malfunction with one or several guns on one side, causing the aircraft to jaw, messing up aim. To which extend the outboard location of guns and subsequent angular alignment of the outter guns on the P-47 promoted vibrations and trajectory jump, could be possibly calculated by someone who has access to structural specifications of the aircraft and it´s gun installations. It should be noted however that weapons which line of fire do extend through the center of gravity of the aircraft are more stable than wing-mounted solutions located further away from the center of gravity.

============================
When it comes to testing new aircraft or determining maximum performance, pilots like to talk about "pushing the envelope." They're talking about a two dimensional model: the bottom is zero altitude, the ground; the left is zero speed; the top is max altitude; and the right, maximum velocity, of course. So, the pilots are pushing that upper-right-hand corner of the envelope. What everybody tries not to dwell on is that that's where the postage gets canceled, too.

XyZspineZyX
06-28-2003, 08:01 AM
And guns mounted on a very heavy plane with big sturdy wings will cause less shake.

Higher effective rate of fire is better for shot where the target crosses the line of fire or the line of fire crosses the target. Low rates of fire allow the target to fly between the shots as it were. So there are times when loads of fast firing guns used within effective range are better than fewer slower firing guns with 2+ times more power per shot.

It would be neat if there was a P47 variant with 2 20mm and 4 .50's, or even cannon in under wing mounts like the FW's could. Imagine a P47 with a pair of 37mm's? It is a big plane even if the 37 is bigger than the Mk103.


Neal

XyZspineZyX
06-28-2003, 11:25 AM
WWMaxGunz wrote:
- Higher effective rate of fire is better for shot
- where the target crosses the line of fire or the
- line of fire crosses the target. Low rates of fire
- allow the target to fly between the shots as it
- were. So there are times when loads of fast firing
- guns used within effective range are better than
- fewer slower firing guns with 2+ times more power
- per shot.

I've mentioned this. Hopefully my program (although
not fully featured) is sufficient to investigate this,
once I've finished. Hopefully I'll get enough time
between house and garden work and so on (guests are
visiting next week, and there is much home improvement
to do!) to finish it and then I can run some simulations
during the week.

XyZspineZyX
06-28-2003, 02:05 PM
Just try sweeping fire across a drone a few times with the arcade arrows set on and make tracks of both MG's and cannon. Tracks run at 1/4 speed reveal so much that anyone can miss while playing. I've used tracks and the view from the target plane back towards mine to check my shooting since IL2 came out... I can't remember if I did with the demo. 1C did real good with putting those arrows in.


Neal

XyZspineZyX
06-28-2003, 03:05 PM
WWMaxGunz wrote:
- Just try sweeping fire across a drone a few times
- with the arcade arrows set on and make tracks of
- both MG's and cannon. Tracks run at 1/4 speed
- reveal so much that anyone can miss while playing.
- I've used tracks and the view from the target plane
- back towards mine to check my shooting since IL2
- came out... I can't remember if I did with the demo.
- 1C did real good with putting those arrows in.

The code I've written should hopefully be able
to simulate some of this, but with the ability to
run various scenarios a few thousand times so it
will be statistically significant. Got to finish
the code first, of course!

XyZspineZyX
06-28-2003, 05:16 PM
WWMaxGunz wrote:
- And guns mounted on a very heavy plane with big
- sturdy wings will cause less shake.

DING! That is what one of the things COL Leonard Kit Carson (one of the higest scoring aces in the 357th) was noting in kinetic enrgy calculations with regards to the P51. He basically debunked the whole notion that firing the guns will slow the plane down by 10s of miles per hour. The same would ratio holds here.

- Higher effective rate of fire is better for shot
- where the target crosses the line of fire or the
- line of fire crosses the target. Low rates of fire
- allow the target to fly between the shots as it
- were.

Agreed 100%

- So there are times when loads of fast firing
- guns used within effective range are better than
- fewer slower firing guns with 2+ times more power
- per shot.

With that said, than assume you have the same ROF for smaller guns (0.50cal) vs larger guns (20mm). Now if you have 1 vs 1, the larger is the way to go. But if you have 6 of the smaller, and only 4 of the larger than you increase your chance of a hit with the smaller 6. In that with the same ROF for both small and large, increasing the count of either will multiply the ROF, and thus make the time between rounds smaller, thus the gap to fly through gets smaller. Granted, the spacing of the guns will factor in, but lets stick with the convergance point for now.

- It would be neat if there was a P47 variant with 2
- 20mm and 4 .50's, or even cannon in under wing
- mounts like the FW's could.

It would be a hoot! /i/smilies/16x16_smiley-wink.gif

- Imagine a P47 with a pair of 37mm's? It is
- a big plane even if the 37 is bigger than the Mk103.

But, bigger typically means smaller ROF.. typically!



TAGERT
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XyZspineZyX
06-29-2003, 08:46 AM
the most important thing to use multi-MG is set the correct convergence, and only fire when a bandit at ur MG convergence distance, in that way, a short 8 MGs burst can really cut a 190 into pieces in FB. /i/smilies/16x16_smiley-happy.gif

but i just think the recoil of multi-MG in FB are so high during gun firing, you can see it during replay, the bullets go every where instead of concetrating on a target like cannons, i don't know this is real or not /i/smilies/16x16_smiley-sad.gif

XyZspineZyX
06-29-2003, 12:12 PM
Ok - code written. Does anyone have any web space
on which I could host the code?

I ran some simulations for two upper and lower
bounds for dispersion (I don't have any definitive
figures for that as yet) assuming a 200m engagement
to a fighter sized target, dead six, with an aiming
error of up to +- 5m (I ran versions for 0m, 1m, 2m,
3m, 4m, 5m). In reterospect I should tweak my code
to give a gaussian distribution centered on the
target, probably, rather than a uniform distribution
of aiming points.

Anyway, with 10,000 experiments for each parameter set
the results are still not totally smooth due to random
variations, so I'll have to run for 100,000 experiments.
The initial results show that 8 guns are slightly
better than 4, with the maximum difference being maybe
10% based on the probability distributions above, and
3m/s target movement in a random direction and a 1 second
firing time. The target movement is to represent a
combination of the firing fighter moving, and/or the
target moving or evading. I haven't simulated roll, just
x-y movement.

I tried 5cm dispersion at 100m and 50cm at 100m, aimed to
take into account ballistics and wing shake - actual figures
for this welcomed!

For 10,000 experiments for a particular dispersion and 6
aiming qualities it took about 30 minutes, but to smooth
out the distributions I am going to up that to 100,000, so
that is going to take all night to run (5 hours per set - 10 hours total) - so I'll try
to post some outline results based on those runs sometime
tomorrow.

XyZspineZyX
06-29-2003, 12:36 PM
I don't know about you guy's but to my expierience Using the P-47 8x .50's seem less effective then beeing shot at by the A.I. P-40's 6x .50's!!!?

9 out of 10 times when those A.I. P-40's hit you you lose control cables over Elavator, Ailleron or Rudder controll while losing rudder doesn't mather to me the others mean Baill out!
last DF vs 4 rookie A.I. one 'rookie' succeeded to kill my engine and at the same time cuting my ailleron cables in a single head on attack!??
Smart bullets i geuss?

XyZspineZyX
06-29-2003, 05:39 PM
AaronGT wrote:
- Ok - code written. Does anyone have any web space
- on which I could host the code?

Cool! Let me know where and when I can get a look at it! You did it in C or C++?



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XyZspineZyX
06-29-2003, 07:12 PM
Aarons proggy is here in .txt format:

Aaron's program (http://www.kolumbus.fi/jan.niukkanen/Aaronsproggy.txt)


-jippo

XyZspineZyX
06-29-2003, 07:22 PM
Just ignore the bit about it being on a 51.2x51.2m
grid - my icon program in Linux only does 200x200
max, so it's on a 20mx20m grid in 10cmx10cm squares.

Here's a some results (takes about 3 hours on an
AMD XP2000) for various aiming accuracies against
a fighter-sized target with relative speed across
the sights of 3m/s with a 1 second burst fired.
Each aiming accuracy requires 100,000 simulations.
The range is 200m.

The gun dispersion is assumed to be a 5cm radius
dispersion at 100m. I've assumed uniform distributions,
which is of course wrong - I am sure there are many
more things that can be added to the simulation.
I realised this was missign yesterday but haven't
got round to changing anything (and probably never
will!)

The results for 10,000 (I accidentally deleted
them - my script tidies up all the results files
when it starts - DOH!) for a wider dispersion
showed similar results.


Low dispersion

We also set the threshold for downing a plane to be 18 .50 hits
or the equivalent and give a 'number downed' figure (for the
20mm cannon this requires 6 hits).

A second figure is double this numbers

I've clipped the last column off all these results
to fit the page for the forum. Jippo has the
full file of this in text format.

% hit | 1 hit means number hitting, given that
this simulation resulted in at least one hit

8 guns

aim_____________0.0_____1.0 ____2.0_____3.0_____4.0
% > 1 hit_______100_____80.7____68.0____57.7____49.6
% hit___________25.7____20.1____15.0____11.7____9.4
% hit | 1 hit___25.7____24.9____22.1____20.3____19.0
damage (avg)____24.7____19.3____14.4____11.2____9.0
damage | 1 hit__24.7____23.9____21.2____19.5____18.2
downed (1) %____53.6____43.0____30.9____24.1____17.6
downed (2) %____22.8____19.3____13.1____9.8_____7.8

4 guns (20mm cannon for damage)

% > 1 hit_______100_____79.7____66.9____57.6____49.2
% hit___________25.9____20.6____14.8____11.3____9.3
% hit | 1 hit___25.9____25.8____22.1____19.6____18.9
damage (avg)____37.3____29.7____21.3____16.3____13.4
damage | 1 hit__37.3____37.2____31.8____28.2____27.2
damge cf 8 guns_1.5_____1.6_____1.5_____1.5_____1.5
d | 1 hit cf 8__1.5_____1.9_____2.2_____1.5_____1.5
downed (1) % ___64.9____56.3____40.5____30.5____24.5
downed (2) % ___46.7____38.9____27.1____19.9____15.2
rel down (1)____1.2_____1.3_____1.3_____1.3_____1.4
rel down (2)____2.0_____2.0_____2.1_____2.0_____1.9

downned(1) % is the proportion that would be severely
damaged by being hit by the equivalent of 18 .50
rounds or more. downed (2) is the same, but for
at least 36 rounds. The rel figures in table 2
are the .50 proportion: 20mm proportion.





Message Edited on 06/29/0306:32PM by AaronGT

XyZspineZyX
06-29-2003, 10:05 PM
AaronGT wrote:

I shouldnt even comment on this yet, in that I have not soaked up the code to see what it is doing, but the comments worry me in that:

* We assume (for this first program)
* that the guns are a super gun of the specified
* rate of fire, mounted coaxially with the aiming
* point. To simulate multiple guns, we assume
* it fires n bullets simultaneously, where n is
* the number of guns.

Simultaneouslys is good for energy transfer, but it kind of negates the "better chance of a hit" thing I have been noting. Simply put, assumed they fire evenly spaced, I know I know, but for the moment assume that. Now take the ROF times the number of guns... Simple example, one gun has a ROF of 10. Two of the same is like having a ROF of 20, 4 of the same is like having a ROF of 40, etc... THUS, that gap down range is much much smaller for the target to SLIP through!!! And, yes, to start off simple you have to assume evely spaced firings and the target is at the point of conversion...

But like I have said, didnt soak up the code yet, thus it wouldnt be the 1st time I have seen code where the comments dont match what it actually does! /i/smilies/16x16_smiley-wink.gif



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XyZspineZyX
06-29-2003, 10:27 PM
tagert wrote:
- * We assume (for this first program)
- * that the guns are a super gun of the specified
- * rate of fire, mounted coaxially with the aiming
- * point. To simulate multiple guns, we assume
- * it fires n bullets simultaneously, where n is
- * the number of guns.
-
- Simultaneouslys is good for energy transfer, but it
- kind of negates the "better chance of a hit" thing I
- have been noting.

If we assume that each gun is a perfect example of
the gun, then the ROF will be steady, and all will
start firing at the same moment. In which case
you will get N bullets fired at the same time, where
N is the number of guns. It's a good starting point.
I don't have any figures on the variability of firing
rates, firing delays, etc., to model. If someone
does then they are free to add that in.

If I'd been more careful about the program I would
have written it with a fine time counter and a series
of firing events that could be triggered, with the
ROF for each gun, firing delay, etc. arranged on
a Gaussian distribution based on proper data. That, I
felt, would take too long and be going a bit over
the top! If someone wants to do it and post the source,
be my guest!

I'd be surprised if it makes much difference to the
overall conclusions, though.

What DOES make more difference is the total lack
of modelling convergence, and the uniform rather
than gaussian aim distribution. Plus there are very
many more experiments for different situations to be done.


- Simply put, assumed they fire
- evenly spaced,

No, they will tend to clump together in time, which
is why I modelled them clumped in time (if perfectly
clumped for simplicity).

- And, yes, to start off simple you
- have to assume evely spaced firings and the target
- is at the point of conversion...

It's actually more reasonable to assume that all
the guns have the same, stable ROF, and no delay
in firing, i.e. 8 rounds for an 8 gun set up
are fired simultaneously, which is how I coded it.

- But like I have said, didnt soak up the code yet,
- thus it wouldnt be the 1st time I have seen code
- where the comments dont match what it actually does!

Apart from the bit I pointed out it should match.
I didn't take the same care I would at work where I
am very, very careful.

XyZspineZyX
06-29-2003, 11:14 PM
AaronGT wrote:
-
- If we assume that each gun is a perfect example of
- the gun, then the ROF will be steady,

Agreed.

- and all will start firing at the same moment.

DISAGREE!!!!!

- In which case you will get N bullets fired
- at the same time, where N is the number of
- guns.

True, but it is biased towards lower gun counts with larger rounds. And negates the basic theam I have sense day one.


- It's a good starting point.

Emmmmmmmmmmm, well, you have to start somewhere, ture, but this in its current form is bias towards lower gun counts with larger rounds... ESPICALLY when, like in our case, the ROF are simular!!! But as is might work, just multiply your ROF by the number of guns and divide the damage by the number of guns.... at least until the code evolves a bit.

- I don't have any figures on the variability of
- firing rates, firing delays, etc., to model.

A guy who is all about statistics cant come up with that? DUDE!! <G> I think, that is to say, my GUT tells me that it is a good model to SIMPLY assume they fire evenly, that is take the ROF times the number of guns. In the AVERAGE would come out to that.

- If someone does then they are free to add that in.

Ok, but you dont need em, the average would come out to evenly.

- If I'd been more careful about the program I would
- have written it with a fine time counter and a
- series of firing events that could be triggered,
- with the ROF for each gun, firing delay, etc.
- arranged on a Gaussian distribution based on
- proper data.

This is a good start, it is just biased towards smaller gun counts with larger rounds. Thus it does not do the .50cals justice.

- That, I felt, would take too long and be going a
- bit over the top! If someone wants to do it and
- post the source, be my guest!

If I get the time, I will, next week I got a big deadline to meet, thus, might not happen. But as long as you realise that it in it's current from is bias towards smaller gun counts with larger rounds

- I'd be surprised if it makes much difference to the
- overall conclusions, though.

I wouldnt! <G>

- What DOES make more difference is the total lack
- of modelling convergence, and the uniform rather
- than gaussian aim distribution.

If your only goal it to see how much lead goes down range and hits near the target, it kind of works, but, from day one I have been noting the fact that with more guns firing, that gap down range to slip through gets smaller.. This sim negates that by assuming they all fire at once.

- Plus there are very many more experiments for
- different situations to be done.

Allways more that can be done! /i/smilies/16x16_smiley-wink.gif

- No, they will tend to clump together in time, which
- is why I modelled them clumped in time (if perfectly
- clumped for simplicity).

Disagree! Or something is missing, because this does not model the CHANCE of a hit than.

- It's actually more reasonable to assume that all
- the guns have the same, stable ROF, and no delay
- in firing,

More REASONABLE? NO! Not at all! TOTALY NOT! If all you want to do is see how much lead went down range over time, it will model that, but it does not model the chance of a hit.

- i.e. 8 rounds for an 8 gun set up
- are fired simultaneously, which is how I coded it.

Roger, and that is wrong IMHO! It's is bias from the get go for lower gun counts with larger rounds!!!

- Apart from the bit I pointed out it should match.
- I didn't take the same care I would at work where I
- am very, very careful.

Roger!


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XyZspineZyX
06-30-2003, 02:39 AM
What a load of crap.. I think its not about US .50 Calls not beeing effective, but they do spread all over the place bit too much.. and some fighters (Like the I-16) take insane amount of .50 Cal fire before they get blown up.. Though this is not the issue for LW-planes.. BF109 and FW190 are fairly easy to kill with .50 Calls..

Just that some planes have bugs for beeing too strong.. I-16 is one of them in my view.. What I really would like to know is the true trajectory of Machine guns and Cannons.. at the moment I find the German 151/20 ridiculous compared to über Soviet ones.. Sure the USSR version had bit higher Muzzle velocity, but how does it occur in real life.. when comparing German MG151/20 and Soviet 20 mm.. in FB Soviet 20mm has a flat trajectory almost to 1000 meters.. and German 20 mm begin to fall down after 200-300 meters.. surely there can't be such a big difference? Also would like to know the actual trajectory of MK108..


My point is.. everyone knows .50 calls are devestating to fighters.. and sure they are... even in FB. P-47 Indeed has weaker .50 calls than P-40.. this is nothing more but a bug, wich will hopefully beeing fixxed in the Patch... My point is its ridiculous to argue about on what purpose US .50 calls were designed for.. we all know that - For engaging fighters! And that they did!




<center>http://koti.mbnet.fi/vipez/shots/Vipez2.jpg </center>

XyZspineZyX
06-30-2003, 02:56 AM
Vipez- wrote:
- What a load of crap..

Well hello to you too!

- I think its not about US .50 Calls not beeing
- effective, but they do spread all over the
- place bit too much..

Based on?

- and some fighters (Like the I-16) take insane
- amount of .50 Cal fire before they get blown up..
- Though this is not the issue for LW-planes..
- BF109 and FW190 are fairly easy to kill with
- .50 Calls..

Well, in general a more complex system is subject to more failers.. With that said the I16 was a very uncomplex system, unlike the BF109 and Fw190s <G>

- Just that some planes have bugs for beeing too
- strong.. I-16 is one of them in my view..

Based on?

- What I really would like to know is the true
- trajectory of Machine guns and Cannons..

That should be pretty easy to calc, all you need is the weight/mass of the bullet (not after fired, not the whole casing and powder) and the inital velocity, two things I know I have see floating around on the web.

- at the moment I find the German 151/20 ridiculous
- compared to über Soviet ones..
Based on?

- Sure the USSR version had bit higher Muzzle velocity,

Finally, something to base something on.. Ok, velocity is very VERY important with regards to bullets! In that velocity is a squared term with regards to the energy. Put in simple terms, a little V goes a long long LONG way. Much longer than the weight/mass with regards to energy.

- but how does it occur in real life.. when comparing
- German MG151/20 and Soviet 20 mm.. in FB Soviet 20mm
- has a flat trajectory almost to 1000
- meters.. and German 20 mm begin to fall down after
- 200-300 meters.. surely there can't be such a big
- difference?

Maybe.. in that Ek = (1/2)*mass*(velocity)^2

- Also would like to know the actual trajectory of
- MK108..

And I would like to know the actual loto numbers for tommorow! <G>

- My point is.. everyone knows .50 calls are
- devestating to fighters..
- and sure they are... even in FB.

Based on?


- P-47 Indeed has weaker .50 calls than P-40..

Based on?

- this is nothing more but a bug, wich will hopefully
- beeing fixxed in the Patch...

Based on?

- My point is

Second point?

- its ridiculous to argue about on what purpose US .50
- calls were designed for..

Based on?


- we all know that - For engaging fighters! And that
- they did!

Well... I see alot of stuff being tossed out there, all seems to be BASED ON EMOTIONS though.. At least Aktan is trying to write a program to BASE HIS statments on! So, thanks for stopping by and adding useful FEELINGS to the topic at hand!



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XyZspineZyX
06-30-2003, 10:43 AM
tagert wrote:
- AaronGT wrote:
--
-- If we assume that each gun is a perfect example of
-- the gun, then the ROF will be steady,
-
- Agreed.
-
-- and all will start firing at the same moment.
-
- DISAGREE!!!!!

If all the gun firing mechanisms are perfect, then
why wouldn't this be the case?

- True, but it is biased towards lower gun counts with
- larger rounds.

It is, but this effect will (a) be small and (b)
is based on what I presume the basic firing mechanism
is (you pull the trigger, the guns fire) with the
simplfication that I am assuming that the mechanisms
are perfect.

- And negates the basic theam I have sense day one.

No. The bullets each have their own trajectories,
and thus there is still more chance of the 8 gun
scenario hitting as there is a wider pattern from
them. What I need are some reliable figures for
that dispersion.

If you like, if I get chance in the next couple of
weeks, is rewrite my program to use a more event-based
system, with delays in firing of each gun taken into
account, and spreads in firing rates from different
guns in an installation, and so on. I need information
on the typical variation in ROF from a set of .50s
and 20mm cannon in an installation, though, to put
in any useful figures. It will probably be a more
complex program, giving basically the same results.

- Emmmmmmmmmmm, well, you have to start somewhere,
- ture, but this in its current form is bias towards
- lower gun counts with larger rounds...

It is, but the simplification is based on the
assumption that 8 .50s will all fire at the
same time (when the trigger is pulled) and at
the same rate (which isn't too bad an assumption).

-- I don't have any figures on the variability of
-- firing rates, firing delays, etc., to model.
-
- A guy who is all about statistics cant come up with
- that?

I don't have a brace of .50s to test the ROF of, nor
know of the results of any such tests!

- I think, that is to say, my GUT
- tells me that it is a good model to SIMPLY assume
- they fire evenly, that is take the ROF times the
- number of guns. In the AVERAGE would come out to
- that.

I am assuming that they are firing evenly per gun.

If the variability is such that this is not the
case then I can easily do some runs where the
equal to the ROF per gun, times the number of gun.
I can do some runs based on that tonight, maybe,
and post the results tomorrow with luck (no promises).


- This is a good start, it is just biased towards
- smaller gun counts with larger rounds.

It's not a bias on my part, though, just modelling
of perfect guns in terms of ROF stability. I'll do
the runs based on totally interleaved firing as that's
the easiest to achieve, and post the results. I would
be surprised if the results are much different.

If anyone knows how I can post tables that don't
get mangled by the board, then that would be handy
to know.


-- I'd be surprised if it makes much difference to the
-- overall conclusions, though.
-
- I wouldnt! <G> -

I'll let you know tomorrow.

- If your only goal it to see how much lead goes down
- range and hits near the target, it kind of works,
- but, from day one I have been noting the fact that
- with more guns firing, that gap down range to slip
- through gets smaller.. This sim negates that by
- assuming they all fire at once.

I'm trying to model the fact that, if the guns
are perfect in their ROF, this is what happens.
But I can do things totally in the other direction
tonight.


- More REASONABLE? NO! Not at all! TOTALY NOT!

Well I don't have any figures on how stable ROFs
are, hence I took the initial assumption that they
are stable, and that it was a reasonable assumption.
But I'll assume that they form a steady stream
(perfect interleaving) tonight and compare the
results.

XyZspineZyX
06-30-2003, 06:54 PM
I do know if there is a scientific way to prove it but the P40 with 6 .50cals seems to pack more punch than the P47 with 8 .50cals. Both online and off.

That is just my experience from flying both planes. I have heard this from many in the FB community that fly both planes.

Yes, I know it is unscientific /i/smilies/16x16_smiley-happy.gif

__________________________


Milo--dont shoot the messanger !

Take it up with :

The Discovery Channel who brodcasted the documentary.

The Pilots that flew the missions and claimed destroyed and damaged Panther & Tiger Tanks.

The gun camara footage that clearly shows a Tiger Tank being strafed from behind and catching fire.

Next get your glasses fixed !

And who was it that verified that no Tigers or Pathers were knocked out from strafing runs?

______________________


>>>Milo wrote :

Sorry, it is a myth, no Tigers were found to have been knocked out because of ricocheting bullets to its >>belly<<. In fact the number of tanks knocked out from the air is over-claimed by a large factor.

I have seen that footage but would not say they were Tigers. But then all German tanks were Tigers, were they not, to GIs.

XyZspineZyX
06-30-2003, 06:58 PM
Sorry typo :

I do not know a scientific way to check the power between the the P40 with 6 .50cals vs the P47 with 8 .50 cals.

XyZspineZyX
06-30-2003, 09:17 PM
Some comparasion of some of the results I've got.

I've been using a low measure of dispersion (a uniform
distribution over a 20cm circle at 200m).

Initially I simulated firing N rounds simltaneously
where N is the number of guns. At tagert's suggestion
I've now done a run (for 8 guns at least) of the
reverse - perfectly interleaved shots (effectively
for an 8 .50 set up a super gun with an ROF of 96).
The results for a 4 gun set up are computing now.

The following is the proportion of experiments with
at least one hit, for the specified aim radius on
the target centre, for 8 .50s (N fired at once),
8 .50s (fired singly - the ROF of 96 simulation) and
4 20mm (4 fired at once).

Aim .50 .50 20mm
0.0 100 100 100
1.0 80.7 78.4 79.7
2.0 68.0 67.4 66.9
3.0 57.7 58.4 57.6
4.0 49.6 50.1 49.2
5.0 43.0 44.8 42.0

The percentage of rounds hitting follows the same sort f shape. As can be seen - the chance of at least one
hit is about the same for 4 guns, 8 guns, 8 firing
in groups of 8, or singly.

There are all sorts of oher stats, but here is one
for at least 18 .50 shots or at least 6 230mm shots (sae sort of power delivered). The figure is the
percentage of trials achieving the goal (this represents
a damaging hit, not a critical hit)

Aim .50 .50 20mm
0.0 53.6 48.4 64.9
1.0 43.0 41.0 56.3
2.0 30.9 30.0 40.5
3.0 24.1 21.4 30.5
4.0 17.6 16.9 24.5
5.0 14.2 15.1 20.0

I'd expect to see a reduction in the 20mm
>= 6 hits proportion for the single round
at a time trial to be a bigger reduction than
that seen between the two sets for the .50, but
not enough to reduce it below the number for
.50s

Next up is to try bigger dispersions, or even
better - proper figures for dispersion of each
weapon if I can find some figures. Tony Williams'
site? This would be the definitive test from this program at least.

XyZspineZyX
07-01-2003, 02:12 AM
Pilots that flew the P-47 had the ability to decide rather they wanted there rouds to scatter at the selected convergance or all rounds concentrate on a single spot.


It seems that in FB they are selected to scatter. It would be nice to have this option in FB. Because I prefer to have my rounds hit roughly the same spot.


Squadmates and I have found little trouble in downing 109s but the 190s seem immune to the .50s. While playing in a scripted mission on our first flight two of us landed a total exceeding 300 hits on a 190 and he just flew away.


Whats funny is we have little trouble at all downing bombers. The JUG makes easy work of them. Even the joke of the game..the TB.


I here good news about the JUG from people who have the beta version of the patch. Like rollrate, climbrate, decentrate, and cruise speed have all been improved. But no word on the .50s yet.

XyZspineZyX
07-01-2003, 04:36 AM
AaronGT wrote:
-
- If all the gun firing mechanisms are perfect, then
- why wouldn't this be the case?

True, but we know that it is hardly ever the case! Example, it is ok to assume a case like that if it is not the BEST CASE for your argument your trying to make. For example, When COL Leonard Kit Carson (one of the hights scoring aces in the 357th) was talking about aircraft slowing down due to guns fring, he did a Kenitic Energy example where he assumed that all guns fired at once.. Which for that case is the WORST CASE for his argument.. Had he trying to argue the point that not all guns fire at once, and based the equation on one, or two, or three firing people would have looked at him funny, and or not put much validation in what he was trying to say.

- It is, but this effect will (a) be small

Disagree 100%!

- and (b) is based on what I presume the basic firing
- mechanism is (you pull the trigger, the guns fire)
- with the simplfication that I am assuming that the
- mechanisms are perfect.

You can, not stoping you, Im just pointing out how wrong it is based on that we know it is hardly ever, IF EVER the case.

-- And negates the basic theam I have sense day one.
-
- No.

YES IT DOES!! In that my basic theam is not how much lead is deposited onto the target, or how long you have to fire to equate a 20mm. My whole premis consists of TWO simple things

1) With more guns you increase your chance of a hit! In that you are multiplying the ROF, thus that spacing down range is tighter, thus harder for the target to slip through
2) Cannons are over kill for fighters! It dont take much to dmg a fighter, and a .50 cal is more than enough most of the time, and what it didnt finish, gravity will do for free.

- The bullets each have their own trajectories,
- and thus there is still more chance of the 8 gun
- scenario hitting as there is a wider pattern from
- them. What I need are some reliable figures for
- that dispersion.

You code is geared toward how much lead you can depost in X amout of time. In the hopes of equating and comparing cannons to .50s. But, it does not simulate the improve chance of a hit you get with more guns! I know you even said it once... I know you pointed out the importance of ROF over just about everything else.. And now to write code that basically negates that feature.. I didnt expect that.

- If you like, if I get chance in the next couple of
- weeks, is rewrite my program to use a more
- event-based system, with delays in firing of each
- gun taken into account, and spreads in firing rates
- from different guns in an installation, and so on.

Im working on that too! /i/smilies/16x16_smiley-wink.gif

- I need information on the typical variation in ROF
- from a set of .50s and 20mm cannon in an installation,
- though, to put in any useful figures.

You can use the same ROF, just different start times, same effect. And I think you would agree if you had a model that took all that varations and start times into account, you would find that the average is probally very very close to dividing up the guns to fire evely spaced! But, that would be the BEST CASE for my argument... So I wont go there. But here is what I hope to code up, take the P47 for example, take the ROF of the .50, divide it by 8.. That will give you the evenly spaced firings.. Now take a rand() function that will take a percentage of that time and add or subtrat it from that start time. You will have to change your code to not step by the "timeStep" amount you use now, but that wont be hard.

- It will probably be a more complex program, giving
- basically the same results.

As it is, it only seems to address the amount of lead deposited on the target.. Which is how most of these guys work it.. But it says nothing for the chance of a hit, in that it disregards that spacing down range that the target could slip through.

- It is, but the simplification is based on the
- assumption that 8 .50s will all fire at the
- same time (when the trigger is pulled) and at
- the same rate (which isn't too bad an assumption).

It isnt if all you want to do is see how much lead went down range in X amount of time, but if you want to calc the chance of a hit, it is a bad assumption to make and is very bised towards low gun counts with larger rounds.. that is to say the P39 would probally do well in this, and we know how hard it is to get a hit on a fast moving target with that 30mm.

- I don't have a brace of .50s to test the ROF of, nor
- know of the results of any such tests!

Dont need it really, just take the stated ROF, and div it by the number of them to get the even spacing firing, then take that even spacing time times a rand() percentage and offset that time a bit. That would simulate it pretty darn well IMHO!

-- I think, that is to say, my GUT
-- tells me that it is a good model to SIMPLY assume
-- they fire evenly, that is take the ROF times the
-- number of guns. In the AVERAGE would come out to
-- that.
-
- I am assuming that they are firing evenly per gun.

No, evenly spaced!! ie ROF/nGuns

- If the variability is such that this is not the
- case then I can easily do some runs where the
- equal to the ROF per gun, times the number of gun.
- I can do some runs based on that tonight, maybe,
- and post the results tomorrow with luck (no
- promises).

Ok.

- It's not a bias on my part,

I know I know! You had the whole thing to think about, It is much easer for the guy to come behind and make comments about one aspct of it after it is done... That guy would be me! <G>

- though, just modelling of perfect guns in terms of
- ROF stability. I'll do the runs based on totally
- interleaved firing as that's the easiest to achieve,
- and post the results. I would be surprised if the
- results are much different.

They wont be very differnt in what you trying to calc, the amount of lead that went down range and hit the target... In that your program also only moves the target around the aim point a little, never exceeding the worst case dispersion.. If I get the time, I would like to see just a square target board that passes through the aim point at different rates... Just one pass threw, left to right, where the aim point pluss dispertion is large enough to not hit the borad at all... I think that would be easier to code up, no bmp needed.. But, I only got to look at it for a little while on sunday... Got it to compile, and added a few typedefs to clean it up.

If anyone knows how I can post tables that don't
- get mangled by the board, then that would be handy
- to know.

I know.. I wish you could use the corier font there...

- I'll let you know tomorrow.

Ok, but I still feel that in it's current form it will not address the chance of a hit as well... in that the aim seems to be pretty dead on.. just a glance, maybe the new poit function does very it off by alot... but... Ill have to see when i run it more.

- I'm trying to model the fact that, if the guns
- are perfect in their ROF, this is what happens.

But they aint! We know that for a fact! Ill be that only 1 out of 10000000 times they all fire at once... Sorry no math, just gut feeling! Oh, that and every GD gun footage I have ever seen! <G>


- Well I don't have any figures on how stable ROFs
- are, hence I took the initial assumption that they
- are stable, and that it was a reasonable assumption.

Disagree.. but even if they were, the start time of each gun would be a littl off.

- But I'll assume that they form a steady stream
- (perfect interleaving) tonight and compare the
- results.

Ok, but, I think the code will still need some tweats to sim the chance improvment due to multipling the ROF by the number of guns.

Oh.. buy the way.. Did you know that some of the P51B's with 4x.50s had electric motors that PULLED/PUSHED the ammo threw the gun? The reason I think was to address jamming, and the side effect was it increase the ROF alot!! I had a book on that somehwere... maybe someone has that info? Was pretty interesting, espically when you consider how improtant the ROF is... Like you noted in a few emails back



TAGERT
-------------------------------------------------------------------------------------------------------
If WAR was not the ANSWER.. Than what the H was your QUESTION?

XyZspineZyX
07-01-2003, 09:30 AM
If all the guns fired the same time every time then it would be very imperfect. It would end up introducing strong harmonic vibrations to the plane as well as creating the concentrated shotgun effect you model. The big trouble with models, with sims is that the results more often point to weaknesses in the model than to what they model.

A 5cm convergence at 100m? Try 1m or 2m convergence at 200m. Try having the target pass through the stream at 15, 30, 45, 60, 75 and 90 degrees at 400kph or have the stream move from 2 degrees below to 2 degrees above the target in 1 full second. Make the gun sweep to follow a target crossing the path of the gun and firing from before to after a perfect deflection situation, as real pilots might.

Forget the robot perfection, it is as flawed as the AI's in many sims and no use to compare realities to much less predict what real performace should be.

But at least Aaron, you don't discuss ballistics way, way over your head and still pound away unlike someone else.


Neal

XyZspineZyX
07-01-2003, 10:01 AM
WWMaxGunz wrote:
- If all the guns fired the same time every time then
- it would be very imperfect.

And I've modelled the other extreme too. In terms
of chances to hit with a small dispersion it doesn't
make much difference.

- A 5cm convergence at 100m?

Yes, much too low - but I am working up to the
higher dispersion figures. 5cm at 100m would
seem ok for a completely static .50, and my intention
was to start with this figure so I couldn't be
accused of hampering the 8 .50s by using too great
a dispersion.

- Try 1m or 2m convergence
- at 200m.

I tried this for the simultaneous firing case,
and it made little difference to the overall figures.
I will be trying it with the larger dispersion
tonight (all other things the same) to see if
that makes any difference. This original trial
was with 1000 simulations, which is too small a set
to smooth out the responses, though.

- Try having the target pass through the
- stream at 15, 30, 45, 60, 75 and 90 degrees at

That's one of the things I plan to do! At about 6 hours
per set of experiments it takes a while. Actually the
target is set to move through at a random angle and
3m/s, to represent target jinking - it's only
about 11km/h.

- Forget the robot perfection, it is as flawed as the
- AI's in many sims and no use to compare realities to
- much less predict what real performace should be.

Well, my intention is not to model all the ballistics,
just to try to simulate enough of the situation to
throw some light on the relative merits of 4 20mm
and 8 .50 setups. Hopefully I've shown that the
difference in probability of at least one hit between
4 and 8 guns, in those instances that I've modelled,
is relative small.

There are a lot of other cases to model - I'm
just hampered by lack of compute power. We have
plenty of it at work - but I am much too honest
to use it even though it is idle some of the time!

So the next experiments are:-

1. Larger dispersion, 6 attack, relative movement 3m/s
2. Larger dispersion, 100m/s relative movement, side
deflection.

XyZspineZyX
07-01-2003, 03:51 PM
You need to offset 10 to 15 degrees left or right or up, not direct 0 degree "on the six" to kill the FW190's. The P47 will rip off wings, cut fuselages in half, explode them, PK from over head a bit...all out to 400 meters at least..

" The first time I ever saw a jet, I shot it down ": General Chuck Yeager, USAF, describing his first confrontation with a Me262 - - -
" Aggressiveness was a fundamental to success in air-to-air combat and if you ever caught a fighter pilot in a defensive mood you had him licked before you started shooting ": Captain David McCampbell, USN, leading U.S. Navy ace in W.W.II.

XyZspineZyX
07-02-2003, 01:51 AM
WWMaxGunz wrote:
- If all the guns fired the same time every time then
- it would be very imperfect.

Agreed.

- The big trouble with models, with sims
- is that the results more often point to weaknesses
- in the model than to what they model.

So very True.

- Try having the target pass through the
- stream at 15, 30, 45, 60, 75 and 90 degrees at
- 400kph

DING! That is what Im coding up right now, in that I think this will highlight the benifit of more guns, in that the ROF get multiplied, thus, you should get more hits, over a wider range as the target passes threw.

- But at least Aaron, you don't discuss ballistics
- way, way over your head and still pound away unlike
- someone else.

Agreed Aaron is doing a good thing here just getting it all started! That and he is not one of those typical ballistics types that all they care about is how much lead was deposited, in that is how they calc the damage.. Which says noting with regards to getting the hits in the fist place.



TAGERT
-------------------------------------------------------------------------------------------------------
If WAR was not the ANSWER.. Than what the H was your QUESTION?

XyZspineZyX
07-02-2003, 11:21 AM
Ok - more results! (I ran my PC overnight!)

I managed to delete one set of results before doing
the full analysis, though :-(

Just increasing the dispersion from a 20cm diameter
circle (uniform distribution) to a 2m one (uniform
distribution) results in the following (NB - I need
to change the distribution to a Guassian one when
I get round to it - I've been running these sims
while doing work on the bathroom, so no time for
programming), with the same 6 attack set up as before:-

The results are :- aim radius, perventage of trials with at least one hit (8 guns) percentage with at least one hit (4 guns)

0.0 100 99.4
1.0 97.2 94.4
2.0 87.6 82.7
3.0 77.6 72.4
4.0 66.7 64.7
5.0 59.0 56.1

So the 4 gun situation is scoring less instances of
at least one hit, but not many less (which was my
original contention). If we look at the number of hits
required to damage or down a plane (norminally taken
to be 18 .50 hits and 36 .50 hits repsectively, or
with one 20mm being the equivalent of 3 .50s, 6
20mm hits and 12 20mm hits) then the 4 20mm set up
potentially does better in terms of downing a plane
by a ratio of about 1.5:1

The next set of simulations were with a side on
target, moving at 100m/s (360km/h or 225mph) with
random direction of relative target movement, and
the larger dispersion, the results look like this
for at least one hit:-

0.0 100 100
1.0 98.7 96.3
2.0 88.5 85.9
3.0 79.9 75.2
4.0 71.7 68.7
5.0 66.3 62.1

Again we see that the chance of at least one hit,
even in this scenario, is not much different
for 4 or 8 guns.

What is very different now is the number of instances
with at least 2 hits, at least 3 hits, etc.

For example, for the worst aiming accuracy for 8 .50s
we get the percentages of trials with at least 1 hit, 2 hits, etc in order to be:

66.3 47.4 22.9 10.7 5.7 1.8

We get very few hits with at least 6 rounds htting, though.

For a 4 gun set up we get (same set up as above)

62.1 20.8 4.0 0.1 0.0 0.0

So that ,matches with what I said previously - the chances
of at least one hit is going to be close for 4 or 8 guns
in most situations, but the number of hits is much
more depdendent on the number of guns.

However.. if we assume that a 20mm round has 3 times
the destructive power of a .50 at 200m (this seems
to be the accepted figure by the USN, and the kinetic
energy alone is considerably more for a 20mm round -
although it's still an approximation of course) then
what we need to do is compare, say, the chances of getting
6 .50 rounds on target with the chance of getting only
2 20mm rounds on target.

In this case we are looing at a probabilty (averaged
over a lot of trials and directions, which may obscure
the details somewhat) of 20.8% versus 1.8%. The 4 20mm
set up seems to have a greater chance of getting more
destrutive power on target. If you look at the roughly
equal chance of 3 20mm rounds htting the target and
5 .50 rounds, we have about 9 plays 5 in the damage
stakes. Roughly it's going to average out to the
1.5:1 ratio that seems to be close to 4*3:8*1.

Ok.. things not modelled so far that should be:-

Gaussian dispersion of rounds
Gaussian distribution of aiming points
Vulnerable areas on the target and armouring (e.g.
not modelling of the lucky .50 hit to something
vulnerable).

The first two aren't too hard to model. The latter -
that's beyond my knowledge.

XyZspineZyX
07-03-2003, 01:54 AM
With the way that multiple guns convergence works, it's not gaussian, bell or any other straight function so don't sweat it.

Am I to assume that your 4 guns have the same rof per gun as the 8 guns?

I wonder how lethal US planes would have been if the Lend-Lease had included getting designs for Russian MG's for US fighters and the people in charge using them?


Neal

XyZspineZyX
07-03-2003, 02:20 AM
My opinion to this tread:
Bigger guns=fewer hits to down=shorter bursts=more kills in snapshots and you can kill in quick passes or large deflection.
Smaller guns=more hits to down=longer bursts=fewer kills in snapshots=you have to stay on the six for a longer period.

But: I don't have any problem with the "jug", just have to stay on the six of my enemy for a little longer../i/smilies/16x16_smiley-happy.gif

XyZspineZyX
07-03-2003, 03:29 AM
Aaron you might find this of some help.

http://www.zenoswarbirdvideos.com/Images/P-47/47GECD.gif



http://www.stenbergaa.com/stenberg/white-dickeautos.jpg

XyZspineZyX
07-03-2003, 10:33 AM
WWMaxGunz wrote:
- With the way that multiple guns convergence works,

I'm talking about the dispersion of a single gun,
rather than the convergence, though. Convergence
is something that isn't in there at all yet!

A lot of natural systems have gaussian (or similar)
distributions, and I suspect the distribution of
rounds from a single gun (i.e. the distribution
of the dispersion of the rounds) would be Gaussian.

What that does do convergence patterns is another
matter.

- it's not gaussian, bell or any other straight
- function so don't sweat it.
-
- Am I to assume that your 4 guns have the same rof
- per gun as the 8 guns?

Each individual gun does, which is basically the
case for a Hispano V as compared to the .50. The
Hispano II has a slightly lower ROF. I don't have
any figures (not that I've had time to really look
so far) for dispersion of .50s, Hispano II, and
Hispano V to fully flesh out the simulations. So
far that are indicative of the sort of behaviour,
but it would take more parameters (true dispersion,
Gaussian distribution on that, increase in dispersion
over the period of firing, convergence etc) to
fully model it anyway. But hopefully what I've done
gives a flavour of the behaviour at least.

- I wonder how lethal US planes would have been if the
- Lend-Lease had included getting designs for Russian
- MG's for US fighters and the people in charge using
- them?

I suppose we can compare the Hurricanes on that
basis, though, as some were rearmed.

XyZspineZyX
07-03-2003, 10:34 AM
Thanks Milo - that'll be handy when I get round
to considering convergence.

XyZspineZyX
07-03-2003, 12:27 PM
AaronGT wrote:
-
- WWMaxGunz wrote:
-- With the way that multiple guns convergence works,
-
- I'm talking about the dispersion of a single gun,
- rather than the convergence, though. Convergence
- is something that isn't in there at all yet!

In that case then at 200m the dispersion is small compared to the size of the target and convergence pattern. It also must add a load of time to your runtime for results. Of course you could set up a table where shots sequence through a set of displacements which while not random would provide spread. A big enough table generated once and what difference would it make? It would run faster than generating randoms. It would also help allow you to table your trig functions instead of using the functions themselves which adds serious runtime. Will there someday be TU's (trig units) to go with the FPU's in CPU's? In this reality and this world there is a place for such!

- A lot of natural systems have gaussian (or similar)
- distributions, and I suspect the distribution of
- rounds from a single gun (i.e. the distribution
- of the dispersion of the rounds) would be Gaussian.
-
- What that does do convergence patterns is another
- matter.

The patterns are much bigger than the scatter else you would never read of the long distance kills that have been recorded. At high altitudes, there is less drag on shots so yes the long shots become more possible as you go up.

-- it's not gaussian, bell or any other straight
-- function so don't sweat it.
--
-- Am I to assume that your 4 guns have the same rof
-- per gun as the 8 guns?
-
- Each individual gun does, which is basically the
- case for a Hispano V as compared to the .50. The
- Hispano II has a slightly lower ROF. I don't have
- any figures (not that I've had time to really look
- so far) for dispersion of .50s, Hispano II, and
- Hispano V to fully flesh out the simulations. So
- far that are indicative of the sort of behaviour,
- but it would take more parameters (true dispersion,
- Gaussian distribution on that, increase in
- dispersion
- over the period of firing, convergence etc) to
- fully model it anyway. But hopefully what I've done
- gives a flavour of the behaviour at least.

At the time when the P47 and P51 were set in stone so to speak, what model Hispano was available? This part of the discussion was partly about why did they go with and stick with the M2? Starting new designs in 1944, the planes would not be upgunned P47's would they?

-- I wonder how lethal US planes would have been if the
-- Lend-Lease had included getting designs for Russian
-- MG's for US fighters and the people in charge using
-- them?
-
- I suppose we can compare the Hurricanes on that
- basis, though, as some were rearmed.


Neal

XyZspineZyX
07-03-2003, 06:01 PM
WWMaxGunz wrote:
-
- AaronGT wrote:
--
-- WWMaxGunz wrote:
--- With the way that multiple guns convergence works,
--
-- I'm talking about the dispersion of a single gun,
-- rather than the convergence, though. Convergence
-- is something that isn't in there at all yet!
-
- In that case then at 200m the dispersion is small
- compared to the size of the target and convergence
- pattern.

I increased it to 2m diameter at 200m in the last
set of simulations posted.

- runtime for results. Of course you could set up a
- table where shots sequence through a set of
- displacements which while not random would provide
- spread.

I just need to go and get a library with a gaussian
function - not a big job - just a case of getting
round to it, and working out the reasonable parameters
to put in to create the required spread. I'll get round
to it eventually! Maybe on Sunday - I have some free time
then.

- difference would it make? It would run faster than
- generating randoms.

true

- At the time when the P47 and P51 were set in stone
- so to speak, what model Hispano was available?

At the time of the P51B - Hipsano II - at the time
the P51D became available - Hispano V. So there was
a cross over. The ROFs are aren't hugely different
(I'll look up the actual figures - I don't have
them to hand). The muzzle velocities also vary - the
Hispano II is a little higher than the M2, the Hispano
V a little lower.

- This
- part of the discussion was partly about why did they
- go with and stick with the M2? Starting new designs
- in 1944, the planes would not be upgunned P47's
- would they?

The Hispano II was fitted in the Mustang IA, though.

I can start redoing sims with the slightly lower ROF
of the Hispano II. It probably won't make much difference
to the figures. They'll get more refined if I use
Gaussian distributions with real dispersion figures, but
I doubt the overall feel will change much, as the
relationship between the guns is relatively constant
despite varying the parameters, basically because you
have a lot of samples for a 1 second burst (approx 96
v 48).

I'll keep working on it, though, periodically. I need
to get back to flying rather than talking about flying,
which is like dancing about architecture (Charlier Parker
quote??)

XyZspineZyX
07-04-2003, 11:30 PM
Hey AaronGT

Well, been working on the code... In a nut shell I took out the bmp compair and added a moving target... where the target is a simple circle... it passes THREW the aim point, the gun(s) detect when the target is near (a scale factor) and begin shooting, and keep shooting while the target is ner, ie as it passes through the aim point. That is the biggest difference.. I also ported the code over to CVI so i could graph the results.

here is a link to the soruce

http://groups.msn.com/FSTAGERT/documents.msnw?fc_p=%2Fdownrange&fc_a=0

I was going to up load the exe so you could run it... but I ran out of space... Thus I need a place to send or upload the exe.. Keep in mind this is very beta.. Anyway, let me know what you think.



TAGERT
-------------------------------------------------------------------------------------------------------
If WAR was not the ANSWER.. Than what the H was your QUESTION?

XyZspineZyX
07-06-2003, 12:21 PM
Any results so far?

XyZspineZyX
07-06-2003, 05:16 PM
AaronGT wrote:
- Any results so far?

Actually no... I dont have any real numbers to plug in.. What I would like to do is plug in some of the command line params you were passing in... Do you have those in a file? That and some numbers on the guns themselfs... init vel, mass, etc... And... trying to figure out a way to calculate the energy due to an HE type of round... and how much HE material was in said round. Basically just working out all the GUI items to make it a usefull tool... Oh, and last thing.. where the H can I upload this *.exe for you and other to download and use?



TAGERT
-------------------------------------------------------------------------------------------------------
If WAR was not the ANSWER.. Than what the H was your QUESTION?

XyZspineZyX
07-06-2003, 09:33 PM
tagert wrote:
- AaronGT wrote:
-- Any results so far?
-
- Actually no... I dont have any real numbers to plug
- in.. What I would like to do is plug in some of the
- command line params you were passing in...

I was using a dispersion (in the second set of experiments)
that gave a 2m diameter uniformly distributed probability distribution for a single gun at 200m. This
was by a parameter that specifies the dispersion radius,
so the parameter for that was 0.005

I was using a rate of fire of 12.0 rounds per second
(more or less correct for M2 browning or Hispano V -
sources vary slightly on the ROFs).

The assumed burst was 1.0 seconds in length.

I'll check what the other parameters were soon. The
above is from memory.


- guns themselfs... init vel, mass, etc...

Tony Williams' site is probably good for finding
all those for a good range of WW2 aircraft guns in
one place. The muzzle velocity for the Hispano II
and M2 .50 are about the same, the Hispano V is a slightly
slower round, same weight. But I can't remember the
exact figures off hand.

- trying to figure out a way to calculate the energy
- due to an HE type of round... and how much HE
- material was in said round.

That's a tricky one. Also the energy won't necessarily
tell you how the destructive power of each round scales.
How much damage is caused by an explosion rather than
an impact may be very different from the actual energies
involved. That's why I went with the USN's statement
that the 20mm round was 3 times (actually they concluded
3.4 times, but I rounded down so as to be conservative)
the power of the .50 round. Given that this was a US
source I didn't think that anyone would quibble too much
with using this as a basis for comparing the destructive
power, as an add on to the probability of hit and quantity
of hits assessments.

- Basically just working
- out all the GUI items to make it a usefull tool...

Very nice!

- Oh, and last thing.. where the H can I upload this
- *.exe for you and other to download and use?

I don't have anywhere to host it, unfortunately. If it
is a good tool, and the assumptions in the code are
all valid, etc., it might be worth asking Tony Williams.

XyZspineZyX
07-07-2003, 02:09 AM
AaronGT wrote:
- I was using a dispersion (in the second set of
- experiments) that gave a 2m diameter uniformly
- distributed probability distribution for a
- single gun at 200m.
- This was by a parameter that specifies the
- dispersion radius, so the parameter for that
- was 0.005

Ok, got it, thanks!

- I was using a rate of fire of 12.0 rounds per second
- (more or less correct for M2 browning or Hispano V -
- sources vary slightly on the ROFs).

Most I have seen give one listing... not sure if that was nominal.. but most likly. Funny thing is the .50 cal does have a few different listings on ROF... anywhere from 750-949 rnds/min. Which seems to depend on if they were BOOSTED or not... I cant find it now, but by BOOSTED I belive it meant they had electric motors to feed the ammo to the gun. I seem to recal a story about that with regards to the P51B. I think it was done to try and fix some jamming problems they were having.. and this was just a side benifit of doing so. But, when the went to the P51Ds with the 6x50s I think the got rid of the BOOST, in that the guns were monted differently and the ammo feed was better, thus less jamming, thus got rid of the el motors.

- The assumed burst was 1.0 seconds in length.

Ok, got it, thanks!

- I'll check what the other parameters were soon. The
- above is from memory.

Kewl Thanks!

- Tony Williams' site is probably good for finding
- all those for a good range of WW2 aircraft guns in
- one place. The muzzle velocity for the Hispano II
- and M2 .50 are about the same, the Hispano V is a
- slightly slower round, same weight. But I can't
- remember the exact figures off hand.

Roger, thanks!

- That's a tricky one. Also the energy won't
- necessarily tell you how the destructive
- power of each round scales. How much damage
- is caused by an explosion rather than
- an impact may be very different from the actual
- energies involved.

Agreed... in an earlier post in this thread a guy posted some numbers that were from Olegs... code for IL2... Problem is it did not include any UNITS... And, it had a listing called POWER... which looks like some scale factor used for HE stuff... I would really like to see how that was determined? Probally that coin toss stuff! /i/smilies/16x16_smiley-wink.gif But, if you have any clue as to the units, please let me know... Here is a cut and past of a portion of that msg

################################################## #####
START
################################################## #####
Here is the direct table of shells and bullets from source code of IL-2.
Comments:

power - here is the TNT, that also modelled (as well as pices of shells).

T - Tracer bullet
AP - Armor-Piercing bullet
APT - Armor-Piercing with Tracer
API - Armor-Piercing Incendary
APIT - Armor-Piercing Incendary Tracer
HE - High-Explosive shell
HEI - High-Explosive Incendary shell
HET - High-Explosive with Tracer
HEIT - High-Explosive Incendary Tracer
MG - M-Geschoss, thin-shell High Explosive

such line destinated the sequence of shells/bullets:
// APIT - AP - AP - APIT - API - API


Table itself.
==========================

Browning .50
// APIT - AP - HE - AP

APIT
mass = 0.0485
speed = 870.0
power = 0.002

AP
mass = 0.0485
speed = 870.0
power = 0

HE
mass = 0.0485
speed = 870.0
power = 0.00148

################################################## #####
STOP
################################################## #####


The speed looks like numbers I see for ROF.. The mass.. I cant come up with ANY COMBO of SI or US units that will work to match... and power... Your guess is as good as mine!


- That's why I went with the USN's statement
-
- that the 20mm round was 3 times (actually they
- concluded 3.4 times, but I rounded down so as to be
- conservative)

Huh... Ok.. God I wish I knew how they came up with that... and how it relates to the Oleg power thing... Funny too, the USN didnt get into HE stuff as much as the Lw... Thus, the Lw 20mm HE stuff might even be more... power?

- the power of the .50 round. Given that this was a US
- source I didn't think that anyone would quibble too
- much with using this as a basis for comparing the
- destructive power, as an add on to the probability
- of hit and quantity of hits assessments.

So far Im just doing Ke with no HE parameters... In that Im not really too interested in the power ans much as the chance of an hit.. In that I think any hit from a .50 is enough to make the guy in the AC that got hit think twice about what he is doing... ie if attacking a bomber.. more than likly once tagged with a .50 he would stop what he is doing and address the .50 knocking on his door! /i/smilies/16x16_smiley-wink.gif

- Very nice!

It is looking cool... the biggest dif between yours and mine is Im not using a *.BMP to check for hits.. I simply more a circle threw the aim point at different speeds and sizes... To semi simulate the tracking of a target.. ie the goal is to see how your chance of a hit(s) improves with a smaller/larger faster/slower farther/closer target.

- I don't have anywhere to host it, unfortunately. If
- it is a good tool, and the assumptions in the code
- are all valid, etc., it might be worth asking Tony
- Williams.

Hmmmm good idea... I think I found place to post it for dl... I know I got room on my ISP... but, I have never done it, ie upload (ftp) to my own space... probaly real simple, just never done it... never needed to! /i/smilies/16x16_smiley-wink.gif



TAGERT
-------------------------------------------------------------------------------------------------------
If WAR was not the ANSWER.. Than what the H was your QUESTION?

XyZspineZyX
07-07-2003, 05:35 AM
Speed in that table is muzzle velocity in m/s. ROF's are not listed either unsynchronized or synchronized. That's one of the advantages of wing guns, they can let loose at full tilt boogie.

2m scatter at 200m is IMHO too wide but I can't say and what the wings are doing to aim may depend on speed and maneuver.

The 2m at 200m is a good figure for convergence circle. Some guns actually get a little extra up or down to provide vertical coverage at least in things I read back in 1999 when the discussions were about EAW. That method is known as pattern harmonization where the other way is point harmonization.

Robert Shaw has some things to say about guns, harmonization and scatter in his book. Did you know that there was a 20mm M2 out in 1941? ROF of 650/min and 10fps higher muzzle velocity. Where he figures the .50 M2 lethality at 6.4, the 20mm M2 counts as 15.9. So the US could have lofted 20mm guns in the planes designed 1941 and later. The 30 cal M2 (1929, rof 1200, mv 2600 fps) rates 1.7. Lethality is expressed as destructive power x number of hits.

I have an old friend who worked for Curtiss-Wright and then Bell before he joined the Navy in WWII. He told me about one experimental plane he worked on (sheet metal man) that was going to be an interceptor and had a 75mm gun planned to use proximity fused shells from extreme range. There was another that had a pusher prop, delta wings and a 37mm gun that got dropped because it was no faster than a Mustang.

I really think that time of fire/ammo load counted more back then, the big push was escorting bombers and when you run half your MG's at a time you might make the whole trip out and back doing the job which wasn't necessarily making kills. Go off and down wasting ammo, alt and E then see how many bombers you lose -- you wingman has to leave his post to cover you!

If you haven't seen it before, check out a copy of Fighter Combat by Robert Shaw, Naval Institute Press. Be sure to read the intro so you know how the info is to be used and read the text as well as the quotes. It's a very good general guide with specific points and data laced through (reads like a brick) but has to be taken right or you'll end up headed off in the wrong direction. You can probably get your library to get a copy, it's normally about $35 but maybe Amazon has used copies for less. Good luck there!

Sorry guys, I got tired and pulled out the book.


Neal

XyZspineZyX
07-07-2003, 12:01 PM
Tagert - those masses look like they are probably
kg.

WWMaxGunz wrote:
- 2m scatter at 200m is IMHO too wide

I used this in response to someone who said
that 20cm at 200m was too narrow, and something
along the lines of 2m at 200m made more sense.
Certainly some people were posting some big
dispersion figures for B17 mounts a couple of
weeks ago, and some were suggesting figures that
seemed to be of the order of 2m at 200m. For
the tests I was doing (slow and fast targets) the
exact dispersion didn't seem to make much difference
to the general flavour of the results, in terms
of the comparasion of the hit chances between the
two installations. Part of that might be that the
dispersion per gun was not modelled by a Gaussian
distribution or other assumptions. I think it is
mostly the diminishing returns issue, though - the
chance of at least one hit is relatively constant
as the number of 'samples' (rounds fired) is high,
but that the expected number of rounds hitting is
much more dependent on the number of rounds fired.
The general character of this relationship seems
to be preserved whatever the detailed parameters,
for the relatively large number of rounds fired in
these cases.

Obviously all bets are off when you are down to the
300 rpm and lower range of a 37mm cannon.

- The 2m at 200m is a good figure for convergence
- circle. Some guns actually get a little extra up or
- down to provide vertical coverage at least in things
- I read back in 1999 when the discussions were about
- EAW. That method is known as pattern harmonization
- where the other way is point harmonization.

Not something I am dealing with at the moment -
the initial presumption was for the perfect
coaxial mount of all guns (physically impossible,
of course, but easier to code initially). I suppose
it is a case of giving each gun its own aim point
based on the convergence pattern, though, so it isn't
an insuperable problem to modify the code.

- Robert Shaw has some things to say about guns,
- harmonization and scatter in his book. Did you know
- that there was a 20mm M2 out in 1941?

There was a Hispano M2, if that's what you mean?

- ROF of
- 650/min and 10fps higher muzzle velocity.

Sounds like the US version of the Hispano II, or
is it different? The ROF and muzzle velocities
are close to the Hispano II, and there was an M2
20mm cannon. Or is it something different again.

- I have an old friend who worked for Curtiss-Wright
- and then Bell before he joined the Navy in WWII. He
- told me about one experimental plane he worked on
- (sheet metal man) that was going to be an
- interceptor and had a 75mm gun planned to use
- proximity fused shells from extreme range. There
- was another that had a pusher prop, delta wings and
- a 37mm gun that got dropped because it was no faster
- than a Mustang.

Sounds a bit like a design similar to the XP-55.
There were a number of designs around then that looked
like they had escaped from Crimson Skies :-)

- I really think that time of fire/ammo load counted
- more back then, the big push was escorting bombers
- and when you run half your MG's at a time you might
- make the whole trip out and back doing the job which
- wasn't necessarily making kills.

One of my points was that you can probably carry about
the same firing time of 20mm ammo in a mythical P47
armed with 4 20mm cannon as one with 8 .50s, and probably
with no loss of overall effectiveness in terms of the
chance of at least one hit, or the chance of enough hits
to put a plane out of action or down it.

- If you haven't seen it before, check out a copy of
- Fighter Combat by Robert Shaw, Naval Institute
- Press.

I'll see if I can track down a copy, thanks.

XyZspineZyX
07-07-2003, 09:47 PM
Hmm..

I found an interesting web site dedicated to LW weaponry and munitions.

http://www.inert-ord.net/luft02h/

The most interesting are the pictures of the actual bullet & shell combos. If such a bullet was to penetrate aircraft frame (in most cases, aluminium) with a speed of over 600 m/s, I believe the frame wouldn't sustain such hit. Think about the hole it would leave onto the frame..

Would the aircraft be airborne anymore if it went straight through the wing ?

-Celorfie

XyZspineZyX
07-08-2003, 01:22 AM
you know.. these looks like interesting topics and i'm very interested in knowing about the p47, but can you guys narrow down your searches to a few paragraphs? i can't read these 5-page long essays.

XyZspineZyX
07-09-2003, 04:06 AM
WWMaxGunz wrote:
- Speed in that table is muzzle velocity in m/s.

Roger.. that was about the only one I could make out.

- ROF's are not listed either unsynchronized or
- synchronized. That's one of the advantages of wing
- guns, they can let loose at full tilt boogie.

/i/smilies/16x16_smiley-wink.gif

- 2m scatter at 200m is IMHO too wide but I can't say
- and what the wings are doing to aim may depend on
- speed and maneuver.

Roger... it will be adj in the program.

- The 2m at 200m is a good figure for convergence
- circle. Some guns actually get a little extra up or
- down to provide vertical coverage at least in things
- I read back in 1999 when the discussions were about
- EAW. That method is known as pattern harmonization
- where the other way is point harmonization.

Huh... do tell! That sounds interesting!

- Robert Shaw has some things to say about guns,
- harmonization and scatter in his book.

Man... 10 years if simming and hunderds of books bought... yet I have not pick that one up yet! My bad! To be honest, if I just pasted all the quotes I have seen over the years I feel like I have read it! /i/smilies/16x16_smiley-wink.gif

- Did you know that there was a 20mm M2 out in 1941?

The 20 mm M2 HISPANO CANNON tha was 94 inches long and weighing 102lb that had a 600 rounds per minute rate of fire, muzzle velocity of 2850 feet per secon and an extreme range o f15,000 feet. Where an exploseive round weighed 4.82 ounces, ie the gun that was simular to the 20 mm cannon used in the spitfire VB?


- ROF of 650/min and 10fps higher muzzle velocity.
- Where he figures the .50 M2 lethality at 6.4, the
- 20mm M2 counts as 15.9.

Huh.. must have been a differnt one! /i/smilies/16x16_smiley-wink.gif

- So the US could have lofted 20mm guns in the planes
- designed 1941 and later.

Yet didnt! Which helps my theory.. we just were not that worried about long range bombers hitting the homeland, but were worried about fast nimble fighters shooting cannons at our bombers.. thus the escort need lots of rounds to dispatch lots of fighters... and a .50 is more than enough to get the fighters att... And, we didnt have to blow it up into a million bits to get it out of the fight (attaking our bombers) and gravity usally took care of the millions bits problem! /i/smilies/16x16_smiley-wink.gif

- The 30 cal M2 (1929, rof 1200, mv 2600 fps) rates 1.7.
- Lethality is expressed as destructive power x number
- of hits.

Cool

- I have an old friend who worked for Curtiss-Wright
- and then Bell before he joined the Navy in WWII. He
- told me about one experimental plane he worked on
- (sheet metal man) that was going to be an
- interceptor and had a 75mm gun planned to use
- proximity fused shells from extreme range.

WOW!

- There was another that had a pusher prop, delta wings
- and a 37mm gun that got dropped because it was no
- faster than a Mustang.

Huh!

- I really think that time of fire/ammo load counted
- more back then,

Agreed 100%! Fighters attacking Fighters (ie escorts) need that... Fighters attacking Bombers need Bigger, and bigger usally translates into less.

- the big push was escorting bombers
- and when you run half your MG's at a time you might
- make the whole trip out and back doing the job which
- wasn't necessarily making kills.

Agreed 100%! And when you consider a .50 blast usally torr it up enough that it was not going to make it home.. the bail out or ditch usally had the same end result.. One Down! That little and smiple fact gets missed by so many in their considertions of a good fighter in WWII.

- Go off and down wasting ammo, alt and E then
- see how many bombers you lose -- you wingman
- has to leave his post to cover you!

EXACTALL! Was not the job! Not for a long time! It wasnt until we had a very good air adv that Doolittle said "Persue and Destroy!" Allowing the escorts to finish them off!

- If you haven't seen it before, check out a copy of
- Fighter Combat by Robert Shaw, Naval Institute
- Press. Be sure to read the intro so you know how
- the info is to be used and read the text as well as
- the quotes.

Is that the same book... or does he have two?

- It's a very good general guide with
- specific points and data laced through (reads like a
- brick) but has to be taken right or you'll end up
- headed off in the wrong direction. You can probably
- get your library to get a copy, it's normally about
- $35 but maybe Amazon has used copies for less. Good
- luck there!

Thanks for the heads up!

- Sorry guys, I got tired and pulled out the book.

LOL!



TAGERT
-------------------------------------------------------------------------------------------------------
If WAR was not the ANSWER.. Than what the H was your QUESTION?

XyZspineZyX
07-09-2003, 04:17 AM
AaronGT wrote:
- Tagert - those masses look like they are probably
- kg.

Really? Ok, it was late, maybe Ill look again, I my have made a mistake in my conversions


TAGERT
-------------------------------------------------------------------------------------------------------
If WAR was not the ANSWER.. Than what the H was your QUESTION?

XyZspineZyX
07-09-2003, 08:59 AM
AaronGT wrote:
- Tagert - those masses look like they are probably
- kg.
-
- WWMaxGunz wrote:
-- 2m scatter at 200m is IMHO too wide
-
- I used this in response to someone who said
- that 20cm at 200m was too narrow, and something
- along the lines of 2m at 200m made more sense.

That was me. I thought you were discussing the convergence area.

There were pilots who had convergence set farther out. Shaw lists typical as 700 to 800 feet, 250m would do. Even with wings as wide as a P47 the angle out to 250m isn't highly obtuse. I wish the battery in my sci calculator wasn't about kicked or that the windoze calc had basic trig (wonder if there's a desktop HP or TI out there? I've gotta check...

Yes, there IS! ;^)

http://www.calculator.org/

Anyway, if the guns span 10m then at 250m the total angle is less than 5 degrees... less than 3 even. A couple of meters circle isn't a whole lot of shake but if the scatter was that bad then what would be the point of setting up opint vs pattern harmonization?

There is something else I didn't really consider and that is the distribution you mention. I worked as a kind of arty spotter in the service long ago and had to study the arty manual in school. There was distribution of shots discussed there but I forget the name of the units they used -- I would call them perhaps standard deviations. Inside one such radius the probability of a hit is 50%. The chance of not getting a hit within each farther radius got smaller and smaller. At 4 radii the chance was only 2% would fall outside. One job of the gun batteries was to keep the groups small, to shrink those radii. So maybe that scatter with 98% within the 2m circle isn't so far off at all and possibly small?

B17 guns did scatter shots. I used to trade emails with a guy who did some of that when he wasn't running the Norden. He said in practice they fired at targets on train cars, the targets were as big as the cars were high and the bullets scattered all over them. I wondered how much was from the MG mounts, the gun shakes from recoil and only the gunner to hold them steady on the swivel in some stations. They didn't practice from turrets. It's also possible that for training the best bullets weren't used. They may have wanted some scatter for door gunners anyway to get at least some hits on fast or dodging planes. Defensive gunnery isn't a long range deal, it would have to use loads of ammo I think.


Neal

XyZspineZyX
07-09-2003, 09:53 PM
WWMaxGunz wrote:
-
- AaronGT wrote:
-- Tagert - those masses look like they are probably
-- kg.
--
-- WWMaxGunz wrote:
--- 2m scatter at 200m is IMHO too wide
--
-- I used this in response to someone who said
-- that 20cm at 200m was too narrow, and something
-- along the lines of 2m at 200m made more sense.
-
- That was me. I thought you were discussing the
- convergence area.

No - just the dispersion for an individual round!


- Anyway, if the guns span 10m then at 250m the total
- angle is less than 5 degrees...

10m would be my guess (to make it easy, angle is
about 10/250 radians, which is er 2*PI*10/250 degrees,
er... where's that calculator :-)

- couple of meters circle isn't a whole lot of shake
- but if the scatter was that bad then what would be
- the point of setting up opint vs pattern
- harmonization?

I did one set of runs (for the slow moving target)
with 20cm, one with 200cm (2m) and the results for
a slow moving target were of the same flavour. I didn't
do a run with the fast moving target, but I could.
I would suspect that the results would broadly have
the same flavour, though, on the whole.

- There is something else I didn't really consider and
- that is the distribution you mention. I worked as a
- kind of arty spotter in the service long ago and had
- to study the arty manual in school. There was
- distribution of shots discussed there but I forget
- the name of the units they used -- I would call them
- perhaps standard deviations. Inside one such radius
- the probability of a hit is 50%.

That's the sort of thing I really need to model
the distributions. The more points the better, but
if it was the radius within which 95% of the points
fell I could model a reasonable gaussian based on that.
There is no guarantee it actually _would_ be a gaussian,
but it's likely to be of that sort of shape - lots of
natural systems of this sort show that sort of behaviour.
I'd just have to guess at the other parameters. It would
be more reasonable than a flat distribution which was
my quick Sunday afternoon solution! It probably won't
change the overall character that much, though, at least
for a slower moving target, as the comparasion between
4 and 8 guns seemed relatively insensitive to the
different dispersions, at least of the orders of
magnitude that I used.

I may add those refinements in, and a smaller
dispersion and rerun them - but it's not a high
priority for me right now :-)

- B17 guns did scatter shots. I used to trade emails
- with a guy who did some of that when he wasn't
- running the Norden. He said in practice they fired
- at targets on train cars, the targets were as big as
- the cars were high and the bullets scattered all
- over them. I wondered how much was from the MG
- mounts, the gun shakes from recoil and only the
- gunner to hold them steady on the swivel in some
- stations.

I can see that recoil and flexible mounts are a bad
combination :-)

- They didn't practice from turrets. It's
- also possible that for training the best bullets
- weren't used.

I doubt they distinguished - having 'bad bullets - training
only' would be a nightmare in terms of logistics when
one of the advantages of the M2 being ubiquitous was
the logistics streamlining.

On the whole, though, you are roughly as likely to
get a hit with 4 guns or 8 guns, you just get more
hits with 8 guns, roughly twice as many with a slow
moving target, slightly better it seems, with a faster
moving target. Then I suppose it comes down to relative
power of the rounds.

What might be helpful is to run a set of simulations
(perhaps with the fast moving target, gaussian aim
and dispersion) with a gradually reducing rate of fire,
showing the chance of at least one hit, and the average
number of hits - e.g. 1 gun, 2 guns, 3 guns, 4guns worth, etc, or maybe even down to 37mm cannon ROF.

XyZspineZyX
07-10-2003, 03:50 AM
AaronGT wrote:
-
- 10m would be my guess (to make it easy, angle is
- about 10/250 radians, which is er 2*PI*10/250
- degrees,
- er... where's that calculator :-)

I'm way out of practice with them, but I do think a decent spreadsheet with stat functions would be a great way to streamline the H out of your simulation. Create a set of 4 concentric circles and anything intersecting would have a certain chance of being hit in some small increment of time based on the chance of a round being in the circle (or really a cylinder of some depth likened to the target) and fractioned down by the amount of area shared with it. I guess that it wouldn't be circles though but one circle and some rings. Complicating that is if the target is moving towards or away from the guns, the size of the circles change. Back when I was young, I'd reduce something like that to a function, but when you get old it's not fun any more. Still to cut individual rounds to a stat would really speed your sim up... 6 HOURS RUNTIME? Yoiiiy!

- I did one set of runs (for the slow moving target)
- with 20cm, one with 200cm (2m) and the results for
- a slow moving target were of the same flavour. I
- didn't
- do a run with the fast moving target, but I could.
- I would suspect that the results would broadly have
- the same flavour, though, on the whole.

Fast moving targets at least across the line of fire is where a high effective ROF really makes a difference in possible hits. I'd say that 6 or 8 .50's would beat the crap out of 2 20mm's there, but 4 is questionable since hits x effectiveness....

You might also factor in weight of guns + ammo for equal firing time as that affects the performance of the fighter. One 20mm round weighs as much as how many 50 cals, and not just the projectiles? If the 20mm guns have equal or near equal ROF then how much heavier is one 20mm than 2 .50's? I don't have data on cartridges but the M2 20mm weight of fire in lbs/min shows as 196 while the M2 .50 shows as 81.

Since there's some question about what the M2 20mm is...

20mm M2, operational 1941, shell .30 lbs, rof 650, mv 2850 fps
20mm M3, operational 1944, shell .30 lbs, rof 800, mv 2750 fps
20mm M39, operational 1953, shell .22 lbs, rof 1500, mv 3300 fps
20mm M61, operational 1957, shell .22 lbs, rof 6000, mv 3300 fps

I would say that the AF valued rof over shell size even beyond WWII at least for fighters.

-- There is something else I didn't really consider and
-- that is the distribution you mention. I worked as a
-- kind of arty spotter in the service long ago and had
-- to study the arty manual in school. There was
-- distribution of shots discussed there but I forget
-- the name of the units they used -- I would call them
-- perhaps standard deviations. Inside one such radius
-- the probability of a hit is 50%.
-
- That's the sort of thing I really need to model
- the distributions. The more points the better, but
- if it was the radius within which 95% of the points
- fell I could model a reasonable gaussian based on
- that.
- There is no guarantee it actually _would_ be a
- gaussian,
- but it's likely to be of that sort of shape - lots
- of
- natural systems of this sort show that sort of
- behaviour.
- I'd just have to guess at the other parameters. It
- would
- be more reasonable than a flat distribution which
- was
- my quick Sunday afternoon solution!

Well, you only really need to "calculate" it once.

- It probably
- won't
- change the overall character that much, though, at
- least
- for a slower moving target, as the comparasion
- between
- 4 and 8 guns seemed relatively insensitive to the
- different dispersions, at least of the orders of
- magnitude that I used.

Consider the delta-v and changing ranges in a BnZ or deflection shot from a 4 oclock position with planes moving at different speeds and turn rates.

- I may add those refinements in, and a smaller
- dispersion and rerun them - but it's not a high
- priority for me right now :-)
-
-- B17 guns did scatter shots. I used to trade emails
-- with a guy who did some of that when he wasn't
-- running the Norden. He said in practice they fired
-- at targets on train cars, the targets were as big as
-- the cars were high and the bullets scattered all
-- over them. I wondered how much was from the MG
-- mounts, the gun shakes from recoil and only the
-- gunner to hold them steady on the swivel in some
-- stations.
-
- I can see that recoil and flexible mounts are a bad
- combination :-)

If the gunner is having a hard time ascertaining the range, closure and lead on a weaving intercepter then scatter is good! How many hits to the front before the fighter goes evasive?

-- They didn't practice from turrets. It's
-- also possible that for training the best bullets
-- weren't used.
-
- I doubt they distinguished - having 'bad bullets -
- training
- only' would be a nightmare in terms of logistics
- when
- one of the advantages of the M2 being ubiquitous was
- the logistics streamlining.

Practice in the States where you are near your local supplier... the 40's was a time of scarcity of metals including lead. In addition to what US forces used there were 1000's of tons of material going to GB, the USSR and straight to the bottom of the seas when cargo ships got nailed, as they did frequently. For sure they recycled what they could but I'm sure that there's different qualities of lead and what got used at home could easily have varied with the good stuff sent out to war.

Perhaps someone here who casts their own for reloads can say if it matters much about lead quality.

- On the whole, though, you are roughly as likely to
- get a hit with 4 guns or 8 guns, you just get more
- hits with 8 guns, roughly twice as many with a slow
- moving target, slightly better it seems, with a
- faster
- moving target. Then I suppose it comes down to
- relative
- power of the rounds.
-
- What might be helpful is to run a set of simulations

Just find the situations where the chances of one hit are a good bit lower with 2 or 4 20mm's than 6 or 8 .50's and see how often that might reasonably occur. Also it might do to cut the target to a cylinder representing the critical hits volume of a fighter, the places where a pilot would really take notice even if the round doesn't disable or detroy the plane. Yeah maybe something for the inner wings if you're trying really hard but isn't this just to get an idea of something?

- (perhaps with the fast moving target, gaussian aim
- and dispersion) with a gradually reducing rate of
- fire,
- showing the chance of at least one hit, and the
- average
- number of hits - e.g. 1 gun, 2 guns, 3 guns, 4guns
- worth, etc, or maybe even down to 37mm cannon ROF.

Multiply the number of hits by effectiveness too. Again the use of stats could reduce runs to one per targeting and triggering situation... and you don't even have to model the rounds.


Neal

XyZspineZyX
07-10-2003, 04:35 AM
WWMaxGunz wrote:
- Fast moving targets at least across the line of fire
- is where a high effective ROF really makes a
- difference in possible hits.

DING! Something I have been saying from the get go! And Im coding it up to test that theory!

- I'd say that 6 or 8 .50's would beat the crap out
- of 2 20mm's there, but 4 is questionable since hits
- x effectiveness....

The few runs I have done seem to agree with that statment.

- You might also factor in weight of guns + ammo for
- equal firing time as that affects the performance of
- the fighter.

True!

- One 20mm round weighs as much as how
- many 50 cals, and not just the projectiles? If the
- 20mm guns have equal or near equal ROF then how much
- heavier is one 20mm than 2 .50's? I don't have data
- on cartridges but the M2 20mm weight of fire in
- lbs/min shows as 196 while the M2 .50 shows as 81.

The few cannon cases I have seen were huge! And, I think they would have to be to get the heavier projectile to match or get close to the V0 of a .50

- Since there's some question about what the M2 20mm
- is...
-
- 20mm M2, operational 1941, shell .30 lbs, rof 650,
- mv 2850 fps
- 20mm M3, operational 1944, shell .30 lbs, rof 800,
- mv 2750 fps
- 20mm M39, operational 1953, shell .22 lbs, rof 1500,
- mv 3300 fps
- 20mm M61, operational 1957, shell .22 lbs, rof 6000,
- mv 3300 fps

Actully the 20mm M2 had a rof of 600. Well at least that is what it says in "The Mighty Eighth War Manual" ISBN 0-87938-508-1

- I would say that the AF valued rof over shell size
- even beyond WWII at least for fighters.

Huh... GOOD POINT! The weight went down, and the rof went up! Which agrees with what I have been saying. A better rof means a better chance of a hit, and the size of the round only maters when you get a hit, so better to do things to improve the chacne of a hit, in that anything the size of a .50 or above is more than enough to wake the pilot up and cause him to rethink what he was doing a second ago.

- Consider the delta-v and changing ranges in a BnZ or
- deflection shot from a 4 oclock position with planes
- moving at different speeds and turn rates.

Exactally!

- If the gunner is having a hard time ascertaining the
- range, closure and lead on a weaving intercepter
- then scatter is good! How many hits to the front
- before the fighter goes evasive?

Exactally! And that seems to be showing up in the few runs I have done! When you consider that WWII aim was mostly done by the pilot and not some computing system... a little spread would be a good thing. And with that said, the convergance just before and after the set point could actually help someone with bad aim, or good aim, but just a very fast moving target.. ie not much time to aim in the fist place. That was the basic senario for most of the USAAF of WWII as escorts.




TAGERT
-------------------------------------------------------------------------------------------------------
If WAR was not the ANSWER.. Than what the H was your QUESTION?

XyZspineZyX
07-10-2003, 12:59 PM
tagert wrote:
- WWMaxGunz wrote:
-- Fast moving targets at least across the line of fire
-- is where a high effective ROF really makes a
-- difference in possible hits.
-
- DING! Something I have been saying from the get go!
- And Im coding it up to test that theory!

I've also coded that up, and tested it,
and it doesn't seem to be the effect you
think it should be!

-
-- I'd say that 6 or 8 .50's would beat the crap out
-- of 2 20mm's there, but 4 is questionable since hits
-- x effectiveness....
-
- The few runs I have done seem to agree with that
- statment.

I haven't done any runs with 2 20mm.
I'll do some over the weekend, but 8 .50s
definitely should be better that 2 20mm
Here the ROF is very different. 2 20mm
isn't very far up the curve of diminishing
returns.

-- You might also factor in weight of guns + ammo for
-- equal firing time as that affects the performance of
-- the fighter.
-
- True!

8 .50s weigh 240kg, 48.5g bullet, 112g round
4 Hispano Vs weigh 168kg, 130g bullet, 257g round.

Assuming 3400 rounds of .50 ammo - we have
240kg (guns) + 381kg ammunition (exluding linkage, since I don't know the weight of those).

That's a total of 621kg and 34 seconds firing
time.

4 Hispano Vs leave us 453kg for ammunition.
This is (again ignoring linkage weights, although
we have less round, so fewer but heavier links,
so it probably roughly works out!) 1762
rounds of ammunition. This works out as
35 seconds of firing time.

Actually the limiting factor is likely to
be the volume for ammunition storage. You
can get about 2 20mm rounds into the
cross sectional area of 5 .50 rounds, so
that would actually give you about 1360
20mm rounds for a firing time of about 27
seconds. The weight of the guns plus ammo
would be about 517kg, excluding linkage weight,
versus 621kg for the 8 .50s and max ammo.
Due to the volume considerations, Tagert
is right about there being less firing time
for 4 20mm cannon, although the difference
is not great. If more wing space could be
devoted to physically storing the ammunition,
then the firing times could be the same in
the same given weight for max ammo.

If we look at a less than max ammo situation
(e.g. 2700 rounds - another common load)
we get firing times of 27 seconds for .50s and 29
seconds for the cannon, in the same weight.
Or in other words, if the P47 had been limited
to the ammunition weight of the P47B, there
would be nothing to chose in firing time
between 8 .50s and 4 20mm cannon.


- Actully the 20mm M2 had a rof of 600. Well at least
- that is what it says in "The Mighty Eighth War
- Manual" ISBN 0-87938-508-1

The M2 is the Hispano II.
The M3 is the Hispano V.

The data for the M2 matches that for the Hispano
II exactly, and ditto for M3 and Hispano V.

- Huh... GOOD POINT! The weight went down, and the rof
- went up!

The total weight of gun installation for
8 .50s is greater than for 4 20mm
Hispanos (II or V).


- A better rof means a better chance of a hit,

Yes, but not a huge amount.

You need to separate 'the chance of a hit'
and the chance of (N) hits. The 'chance of a hit'
is P(1 hit) and doesn't vary very much between
4 guns and 8 guns. P(20 hits) (the enough
to do some damage if they are .50 rounds perhaps)
DOES vary a lot. But if the rounds vary
in effectiveness a fairer comparasion is
P(20 hits) and P(20/k) hits where k is
some scaling factor of the round's effectiveness.

- and the
- size of the round only maters when you get a hit, so
- better to do things to improve the chacne of a hit,

But P(1) is very nearly the same in both
cases...


-- Consider the delta-v and changing ranges in a BnZ or
-- deflection shot from a 4 oclock position with planes
-- moving at different speeds and turn rates.
-
- Exactally!

ROF of 8 guns might begin to make a difference
here, although I tried to take into account
some high speed engagements. I suspect
that P(1) for 4 and 8 guns will not be
much different.


-- If the gunner is having a hard time ascertaining the
-- range, closure and lead on a weaving intercepter
-- then scatter is good! How many hits to the front
-- before the fighter goes evasive?
-
- Exactally!

Actually filling an area with a fairly
small quantity of rounds (a single .50
on a flexible mount) in a random way gives
a very low P(1). In the simulations I did I
assumed that the target solution was
roughly right. If it is very off, then the
ROF of a single gun will be insufficient
(In fact I am bemused that you can say
that firing 4 guns at a target with reasonable
accuracy is insufficient and then that a single
flexible mount almost at random is a workable
solution - these two views don't square up -
it's a bit like saying if a sniper rifle can't
hit a target with a proper aim, the best
way to hit the target is to use a shotgun
and close your eyes...)

However, a series of indepdently targeted
poor solutions with a large enough combined ROF
(the equivalent of 10 gunners from neigbouring
B17s firing at the same target) even if each
solution is poor does begin to be a viable
way of shooting down a plane. This is part
of the concept behind the defensive box. You
need a lot of weight of fire for such poor
firing solutions to become effective.

- aim was mostly done by the pilot and not some
- computing system... a little spread would be a good
- thing.

A little - the amount of spread from a single
.50 flexible mount, given the amount of space
there is wouldn't hurt, but the chances of hitting would be small in any case, and you
begin to get to almost random chances.

XyZspineZyX
07-10-2003, 02:48 PM
AaronGT wrote:
-
- tagert wrote:
-- WWMaxGunz wrote:
--- Fast moving targets at least across the line of fire
--- is where a high effective ROF really makes a
--- difference in possible hits.
--
-- DING! Something I have been saying from the get go!
-- And Im coding it up to test that theory!
-
- I've also coded that up, and tested it,
- and it doesn't seem to be the effect you
- think it should be!

Yes you have... but... your code is not looking at what Im now looking at! I have allways felt that more guns will improve your chance of a hit, and that a hit from a .50 is more than enough to damage a fighter. That is to say escorts realise they didnt need to blow a fighter to bits, just damage it enough and gravity will do the rest for you.

Now with that said, let me tell you what my code does. For this example lets compair two plane with the same types of guns (ie same ROF), but one has 4 of them and the other has 6. Kind of like the P51B vs a P51D. Granted some P51Bs had a higher ROF due to boost, but disregard that for now.


Your code compairs the percentage of:

100*(num of hits)/(num rnds fired)

And even with that it shows that more guns will give you a better percentage... but as you noted.. not that much better!

But that is not a good test IMHO! Think about it, less guns fire less, thus your test will allways be close (ie nearly normalized).

case 1 (4x.50s)

#=100*(num of hits)/(time of fire)
#=100*(400)/(800)
#=100*.5
#=50

case 2 (6x.50s)

#=100*(num of hits)/(time of fire)
#=100*(600)/(1200)
#=100*.5
#=50


What I coded up is:

(num of hits)/(time of fire)

That is to say when you have a target moving at a fixed rate threw the aim point, the time spent in the firing zone will be the same for both tests. Thus the aircraft in our test (ie P51D like) will put more lead on the target in a fixed amout of time. That is to say, you have a beter CHANCE OF A HIT in a fixed amout of firing time. So lets say this:

case 1 (4x.50s)

#/i/smilies/16x16_smiley-sad.gif num of hits)/(time of fire)
#/i/smilies/16x16_smiley-sad.gif 400)/(10)
#=40

case 2 (6x.50s)

#/i/smilies/16x16_smiley-sad.gif num of hits)/(time of fire)
#/i/smilies/16x16_smiley-sad.gif 600)/(10)
#=60

Note all the numbers presented here are just for example, not results from the program I coded up.





TAGERT
-------------------------------------------------------------------------------------------------------
If WAR was not the ANSWER.. Than what the H was your QUESTION?

XyZspineZyX
07-10-2003, 03:20 PM
tagert wrote:

- Yes you have... but... your code is not looking at
- what Im now looking at! I have allways felt that
- more guns will improve your chance of a hit,

Which is the question I was looking at.


- that a hit from a .50 is more than enough to damage

_A_ hit isn't (at least the chances of a single
hit causing significant damage are small). Several hits might be.


- a fighter. That is to say escorts realise they didnt
- need to blow a fighter to bits, just damage it
- enough and gravity will do the rest for you.

Which is why I looked at some numbers for
a number of .50 rounds enough to damage it,
and the equivalent number of 20mm rounds to
do about the same amount of damage.

- Your code compairs the percentage of:
-
- 100*(num of hits)/(num rnds fired)
-
- And even with that it shows that more guns will give
- you a better percentage... but as you noted.. not
- that much better!

Not for a single hit - not much difference.


- But that is not a good test IMHO! Think about it,
- less guns fire less, thus your test will allways be
- close (ie nearly normalized).

The reason my code does that is that is
what the original debate was about! Your
contention was originally that the chance of
a hit (P(1)) was improved notably by
increasing the number of guns. I said
this was incorrect, and my simulations show
this.

-
- case 1 (4x.50s)
-
- #=100*(num of hits)/(time of fire)
- #=100*(400)/(800)
- #=100*.5
- #=50
-
- case 2 (6x.50s)
-
- #=100*(num of hits)/(time of fire)
- #=100*(600)/(1200)
- #=100*.5
- #=50

I am a bit confused what all those figures
above mean. The time of fire figure there
makes no sense to me whatsover. If you
mean 'total rounds fired' then it makes
total sense, and also fits with what I am
saying (see below for more details).


- the firing zone will be the same for both tests.

Which is why I used the same firing time
in my tests.

- Thus the aircraft in our test (ie P51D like) will
- put more lead on the target in a fixed amout of
- time. That is to say, you have a beter CHANCE OF A
- HIT in a fixed amout of firing time.

which is why I used a fixed firing time too!


- So lets say

Which is exactly what my results said too!

Basically P(x), where x is the number of rounds
that hit in a given simulation is a function,
and for larger values of x, then P4(x) (pretend
the 4 is a subscript for the number of guns!)
is about half P8(x) (which is what you were alluding to above). For small values of x
(notably x=1) then P4(x) ~= P8(x).

This is all I've been trying to show, and to
disavow the myth that P4(x) << P8[x). It isn't
the case.

From doing a gross average (large x) we can't
deduce the behaviour at small x in a simple way,
which is what I feel you keep trying to convince
me you can!

The supplemental part to my argument is that
P4(x/3) >= P8(x). I.e. you can get enough
rounds on target with a 4 20mm cannon arrangement
to do at least as much damage (on average) as
a 8 .50 set up. My simulations seem to bear this
out.

The other thing I wanted to point out was that
in terms of weight, the 4 20mm cannon set up
has a similar firing time to the 8 .50 set up
as there are fewer guns, and a lower over all
ROF, which means that since firing time is
roughly the same then you have the same abililty
to take speculative shots. What I did note
was that the volume of rounds is more of an
issue than the weight, but with a standard
ammunition load (about 300rpg, as opposed to
max ammo loads) then the volume issue also
vanishes, and you end up with two mounts with
the same firing time and same all up weight
(or pretty close to it).

XyZspineZyX
07-10-2003, 08:49 PM
Dividing hits by fire time...

X = H/T then the smaller T is, the larger X is, but what is X?

Hits/second * fire time makes more sense to me.

Aaron... how much fire time are you using to calc PN(1)?
A good pilot uses short bursts, 1/4 second maybe unless dead on target and the target needs it. He might administer multiple bursts but a heavy trigger finger wastes ammo. In 1/4 second into the cockpit or engine you have good chance of a kill with those MG's, there's many more places where any hit is much as critical as any other than when say peppering the wings or tail.


Neal

XyZspineZyX
07-11-2003, 05:44 AM
WWMaxGunz wrote:
- Dividing hits by fire time...
-
- X = H/T then the smaller T is, the larger X is, but
- what is X?

Hits Hertz! <G> Actually, I was thinking of that as I was driving to work... What is X.. It is something we are not use to looking at... That is to say, most folks look at hit percentage... but that does not really show how a more guns improve your chance of getting a hit on a fast moving target... Basically Im trying to compair two different types of guns, and number of them for a fixed amout of firing time.


- Hits/second * fire time makes more sense to me.

(#/s)*s = #

I was thinking that too... but... the #/s vary from fire to fire, in that one might be a miss... if you hit every time, it is the ROF... Im open to sugestions here! /i/smilies/16x16_smiley-wink.gif



TAGERT
-------------------------------------------------------------------------------------------------------
If WAR was not the ANSWER.. Than what the H was your QUESTION?

XyZspineZyX
07-11-2003, 06:26 AM
AaronGT wrote:
-- Yes you have... but... your code is not looking at
-- what Im now looking at! I have allways felt that
-- more guns will improve your chance of a hit,
-
- Which is the question I was looking at.

Actually your leaning more towards what I have seen people do in the past. Trying to come up with how many of these will equal one of those. As if there was some magical number to be reached that meant destruction. There isnt one! And that whole damage thing is one of the grayest things in a sim. With alot of work we can usally get hard numbers for things like speed, drag, etc.. but who is to say what the majic number is for destruction of the target? There are some rules of thumb that some abide by, but I have never agreed with those, in that they are just a wag really.

-- that a hit from a .50 is more than enough to damage
-
- _A_ hit isn't (at least the chances of a single
- hit causing significant damage are small). Several
- hits might be.

Disagree 100%!! You have never fired a .50 cal have you? If you could see the power that things has to rip through steel you would realise that it only takes one! That is to say, one in the right place... and there are PLENTY of right places and you can take a fighter out of the fight! A .50 threw a engine block... just a mater of time, short amout.. a .50 threw a canopy, even less time! <G> Granted, there are plenty of spots where it would not have much effect.. and for every story you can find of a fighter making it back with a bunch of .50 cal holes in it, Im sure you could find hunderds of storys where one crashed with much less... only hard to prove! And, there are plenty of storys of AC making it home with 20mm holes in them.. So there is no majic number of damage... that is just LUCK! And a whole OTHER simulation! I still contend, if your seeing tracers from a .50 wizz by, let alone feel a few strike your AC... Im sure that 99 out of 100 are going to stop what EVERY there were doing and start doings something else!!! And that is all an escort really cared about!!

- Which is why I looked at some numbers for
- a number of .50 rounds enough to damage it,
- and the equivalent number of 20mm rounds to
- do about the same amount of damage.

And that whole how many of these needed to equal one of those thing is all bunk IMHO! What was important was improving your chance of a hit, any hit!! In that once hit, 99 out of 100 broke off and started donig something else... Now I know that is going to be hard to belive for alot of folks here with their sim experane to go by.. in that 99 out of 100 press on until thier prop starts to mess with the tail of the other ac... Funny how a little thing like not dying makes a John Wayne out of eveyrone! /i/smilies/16x16_smiley-wink.gif

- Not for a single hit - not much difference.

But we aint talking single are we! /i/smilies/16x16_smiley-wink.gif

- The reason my code does that is that is
- what the original debate was about! Your
- contention was originally that the chance of
- a hit (P(1)) was improved notably by
- increasing the number of guns.

Still!

- I said this was incorrect, and my simulations
- show this.

No, what your shows is a gun that fires fast will have about the same hit percent as a gun that fires slow, ie

hit percent = 100*(num of hits)/(num rnds fired)

So assume a hit percent of say 50%

A fast fring gun will fire more rounds, thus divides by more keeping the percent about the same when compaird to a slow firing gun. ie

fast
50% = 100*(500)/(1000)

slow
50% = 100*(100)/(200)

Now I think it is obious that if you hit something 500 times vs 100 times that you would say the chance of a hit is better with a fast firing gun. That is what Im trying to simulate.


- I am a bit confused what all those figures
- above mean. The time of fire figure there
- makes no sense to me whatsover. If you
- mean 'total rounds fired' then it makes
- total sense, and also fits with what I am
- saying (see below for more details).

Roger was a type-o on the fist line, if you read above that you will see I said one thing and typed another, here is what I ment to say

case 1 (4x.50s)
#=100*(num of hits)/(num of rnds fired)
#=100*(400)/(800)
#=100*.5
#=50

case 2 (6x.50s)
#=100*(num of hits)/(num of rnds fired)
#=100*(600)/(1200)
#=100*.5
#=50

Which is what I just said again above! <G>


- Basically P(x), where x is the number of rounds
- that hit in a given simulation is a function,
- and for larger values of x, then P4(x) (pretend
- the 4 is a subscript for the number of guns!)
- is about half P8(x) (which is what you were alluding
- to above). For small values of x
- (notably x=1) then P4(x) ~= P8(x).

But it is intended for that whole how many of these equal one of those, for the dmg calc that I think is bogus. Fast guns get more hits, but fire more, so the percentage comparsion to slow guns that fire less is going to be close. But if you look at just the number of hits in a an amout of time, that shows how your chance of a hit is better with more guns. Which is what I have been saying was important to escorts, that and the fact they dont need to blow up a fighter to take it out of the fight, pluss the US didnt have any real concerns of heavy bombers.. Bigger slower firing guns are good for bigger slower moving targets, faster firing smaller guns are better for faster smaller targets. I said it before, you dont need a sledge hammer when a ball pean will do. Sure you could, but it is a waste! Gravity will do that part for you.

- This is all I've been trying to show, and to
- disavow the myth that P4(x) << P8[x). It isn't
- the case.
-
- From doing a gross average (large x) we can't
- deduce the behaviour at small x in a simple way,
- which is what I feel you keep trying to convince
- me you can!

Nope! Just looking at it from a whole different prespective than you are looking at it. You trying to see how many of these equal one of those... Im saying you dont need to equal one of those, you need to improve your chacne of a hit, because one hit would be enough to cause 99 out of 100 to stop and rethink what they are currently doing. Hell the sound of a .50 on the ground is enough to have that effect! <G> You ever fired one? They will terr some S up!!

- The supplemental part to my argument is that
- P4(x/3) /i/smilies/16x16_smiley-mad.gif P8(x). I.e. you can get enough
- rounds on target with a 4 20mm cannon arrangement
- to do at least as much damage (on average) as
- a 8 .50 set up. My simulations seem to bear this
- out.

Yup, in that most people look at it like that. They are trying to equate the damage... as if there was some majic number to obtain that would equal damage.. There really isnt, for every story of a plane making it home with a bunch of holes in it there were probally 10 that didnt make it home with less holes... A .50 is more than enough to damage an AC, and way more than enought to cause 99 out of 100 pilots to rethink what they are donig.. damage or no damage, the end result is the same... the escort got the attacker to break off.

- The other thing I wanted to point out was that
- in terms of weight, the 4 20mm cannon set up
- has a similar firing time to the 8 .50 set up
- as there are fewer guns, and a lower over all
- ROF, which means that since firing time is
- roughly the same then you have the same abililty
- to take speculative shots. What I did note
- was that the volume of rounds is more of an
- issue than the weight, but with a standard
- ammunition load (about 300rpg, as opposed to
- max ammo loads) then the volume issue also
- vanishes, and you end up with two mounts with
- the same firing time and same all up weight
- (or pretty close to it).

Again, not saying your way is wrong! Hardly! It is very good for equating things to see how many of these equals one of those. That is not what Im looking for, Im looking for how your chance of a hit is imporved by haveing more guns, in that your ROF is multiplied!! That and the simple idea that you dont need a sledge when a ball pean will do, where do is brush him off his attack, move onto the next guy and let gravity do the rest. Which also explains why alot of the US pilots didnt get credits for kills, but that is another story... or sim? /i/smilies/16x16_smiley-wink.gif



TAGERT
-------------------------------------------------------------------------------------------------------
If WAR was not the ANSWER.. Than what the H was your QUESTION?

XyZspineZyX
07-11-2003, 07:33 AM
I spent some times in the service and became very familar with the browing M2 Heavy Barrol.50. The only thing I dont like with the IL2FB is the sound.

A .50cal sounds like a car wreck, I can't imagine 8 of them at once.

The IL2FB .50's sound like a water spicket!

http://www.352ndfightergroup.com/shared_art/352_487.gif

XyZspineZyX
07-11-2003, 08:30 AM
Of course P(many) becomes more important when you take in the possibility of critical hits perhaps... the thing is that explosive shells are easier to make critical hits with....

Shaw did make a set of Lethality numbers for the guns listed so it's not complete bull although not a precise measure of all situations either. Just so you know he's not a casual writer/historian -- from the jacket: Master degree in AE, 14 year veteran US Navy fighter pilot including carrier based fighter pilot, operational test pilot and test director for the Navy Air Combat Maneuvering Range. Over 4,000 air hours logged mostly in fighters such as F-4 and F-14. Rank at publish time was Commander. Also a civilian flight instructor and consulting engineer specializing in fighter AC and weapons systems performace evaluation. Founder and president of Fighter Command International, which does consulting in air combat training and engineering. The highest reference though is the respect that professional fighter pilots give his work.

What he does have to say that bears directly on this thread is what amounts to the observation that US designers built to counter German and Japanese fighters while the Germans built more to counter bombers. He notes the problems of guns in the wings and and the problems of recoil slowing planes down as an especial problem with planes already going slow stalling out. Failure of a gun to fire on one side (jam) caused planes to yaw. Combine those two! And yet still the designs were made the way they were because they were effective. We did have the P-38's and weren't there other US planes with 20's in 1941 and before? For sure if those cannon were better for the purposes planned then that's what would have been used.

OTOH, while Browning made cannon as well as MG's the cost in time, materials, tooling and money may have entered into the equation as there were LOTS of those guns made. Using the same guns in fighters that bombers, tanks and other vehicles carried did simplify ammo supply surely all the way to emergency supply shuffles.

Shaw didn't have anything bad to say about the use of 50's in WWII US fighters. He didn't say they were stellar either. His measure of fighter guns through history is based on a lethality factor based on kinetic energy and rate of fire, then he goes on to note that explosive shells are underrated in that scheme. The lethality of the 20mm at 15.9 is only with solid AP shot. The .50 gets 6.4 there.

I'd bet the whole trick is how you use what you got and either way works okay. You got cannon, you use em one way and you got beaucoup MG's you do it different. We know the .50's did down fighters, sometimes fast. I guess in the sim it should work down to pick what you like and fly it.


Neal

XyZspineZyX
07-11-2003, 10:54 AM
WWMaxGunz wrote:
- Aaron... how much fire time are you using to calc
- PN(1)?

One second.

I can see the effect of shorter bursts if you like
(I'll be running a lot of stuff this weekend!)

XyZspineZyX
07-11-2003, 11:24 AM
tagert wrote:
- Actually your leaning more towards what I have seen
- people do in the past. Trying to come up with how
- many of these will equal one of those. As if there
- was some magical number to be reached that meant
- destruction. There isnt one!

I know there isn't.

What I am trying to do is to determine the probability
of inflicting a certain amount of damage on the target
(which is sort of the point of firing at it). The
simplest way to calculate it is to assume that
any hit on target from a particular gun does a certain
quantum of damage, and that some quanta are bigger
than others. It's a simplification, but I don't think
it is a particularly bad initial simplification. Any
more than that, and I am into the realms of reimplementing
Forgotten Battles, which is too much work. My intention
is to give a flavour of the relationship between
8 .50s and 4 20mm cannon.

--- that a hit from a .50 is more than enough to damage
--
-- _A_ hit isn't (at least the chances of a single
-- hit causing significant damage are small). Several
-- hits might be.
-
- Disagree 100%!! You have never fired a .50 cal have
- you?

Yes, but only firing blanks. WW2 reenactment would
have been very dangerous for the German section if
the US Army section (to which I belonged) if we'd used
live ammunition.

If you examine combat reports
it is pretty obvious that the chances of one .50 hit
bringing down a plane is very small indeed unless it is
a very lucky hit.

- If you could see the power that things has to
- rip through steel you would realise that it only
- takes one! That is to say, one in the right place...
- and there are PLENTY of right places and you can
- take a fighter out of the fight!

Yes, but the comparasion by the USN of the .50 and
20mm cannon suggests that you have to hit a whole
heap more places (on average) with a .50 than a
20mm cannon.

You are (to coin a phrase) shooting yourself in the
foot a bit here. Since it is demonstrable that P4(1)
and P8(1) are close in most situations, and I can
demonstrate that a single 20mm round does more damage
and a single hit is more likely to down a plane when
it hits a less vital area than a .50 hit in the same
area, then this is an argument for the use of 20mm
cannon in preference to the .50. In fact it is the
argument that the French Air Force used (admittedly
in comparasion to the French 7.5mm guns, modified
Brownings with approx 1800 rpm ROF) for the use
of the Hispano cannon!

- much effect.. and for every story you can find of a
- fighter making it back with a bunch of .50 cal holes
- in it, Im sure you could find hunderds of storys
- where one crashed with much less...

Ditto .303...

- prove! And, there are plenty of storys of AC making
- it home with 20mm holes in them.. So there is no
- majic number of damage...

I agree, but I think you are getting a bit obsessed
with the power and mystique of the .50 over and above
actual abilities of the weapon.

- And that whole how many of these needed to equal one
- of those thing is all bunk IMHO!

It's an approximation. Clearly the 20mm round has
more power than the .50. It has more than twice the
kinetic energy at the muzzle, even discounting its
explosive energy.

- What was important
- was improving your chance of a hit, any hit!!

Back to this old chestnut. In that case the remember
P4(1) ~= P8(1)! The chances of a hit, any hit, are
about the same. I don't know why you don't understand
this, and after simulations pointing it out!


-- I said this was incorrect, and my simulations
-- show this.
-
- No, what your shows is a gun that fires fast will
- have about the same hit percent as a gun that fires
- slow, ie
-
- hit percent = 100*(num of hits)/(num rnds fired)

My code computes this as an interesting side value,
but my analysis is not based on this. You are
completely misunderstanding what I actually did.

I run 100,000 trials. I determine, in that trial, without
reference to any other trials. I.e. I determine if at
least one hit has occured for that one of 100,000 trials.

Over the 100,000 trials I determine how many of those
trials socred a hit.

The P(1) figures I quoted are (number of trials in which at
least one hit occured)/(number of trials). I assume that given 100,000
trials I have computed the P(1) given random startup
conditions for a trial. In reality P(1) is dependent
on the startup conditions. I give the aggregate for all
startup conditions just to given an average over a whole
range of situations, rather than just one specific one,
to give an overall flavour.

There is no aggregation of the type you suggest.


- A fast fring gun will fire more rounds, thus divides
- by more keeping the percent about the same when
- compaird to a slow firing gun. ie

This is based on a gross misunderstanding of the simulations
I ran.


- Roger was a type-o on the fist line, if you read
- above that you will see I said one thing and typed
- another, here is what I ment to say
-
- case 1 (4x.50s)
- #=100*(num of hits)/(num of rnds fired)
- #=100*(400)/(800)
- #=100*.5
- #=50

Ok - but that's not what I am calculating when I calculate
P(1)

I calculate
100 * (num of trials in which at least one hit occured)/
(num of trials)

This is very different to what you are suggesting I am
doing.

I also calculated P(x) where x > 1 for various
values of x, where I guessed that for a .50 x was
a sufficient number of hits to cause serious or
catastrophic damage based on suggestions from other
sites about how many times pilots hit the targets.
(Yes, it's an average figure - and a lucky hit is
possible).

- Which is what I just said again above! <G> -

Yes, but you are misunderstanding the trials I ran.

- But it is intended for that whole how many of these
- equal one of those, for the dmg calc that I think is
- bogus. Fast guns get more hits, but fire more, so
- the percentage comparsion to slow guns that fire
- less is going to be close.

It's not what I am caculating for P(1).

Of course for P(x) where x >> 1, then ROF has an effect.
I thought that was your point - that ROF was beneficial.
I am actually agreeing with you that in terms of getting
a number of rounds on target, where that number >> 1
then ROF is very beneficial. It just isn't true for low
values of x. In suggesting examining P4(x/3) and P8(x)
I am trying to approximate the power of the rounds in
a simple way, to make the problem tractable, at least
as a simple model.

- But if you look at just
- the number of hits in a an amout of time, that shows
- how your chance of a hit is better with more guns.

Your chance of _a_ hit doesn't change much, which
I have demonstrated multiple times, now. Your chance
of _several_ hits is better with more guns.

- Which is what I have been saying was important to
- escorts, that and the fact they dont need to blow up
- a fighter to take it out of the fight, pluss the US
- didnt have any real concerns of heavy bombers..

And what I am trying to show is that if you assume
that a 20mm round is more powerful than a .50 round
and that a few 20mm rounds will take a fighter out
of the fight, then P4(few) ~= P4(many), and so you
have no great advantage with the .50s. In fact given
that P4(1) ~= P8(1) and a 20mm round is more powerful,
then you might actually be better off, although at
the risk of P4(1) being very slightly lower than P8(1).
The difference between P4(1) and P8(1) seems to be
very small in most instances.

There is some balance, and yes you are -very slightly-
more likely to hit with 8 guns, but the difference is
small.


- Bigger slower firing guns are good for bigger slower
- moving targets, faster firing smaller guns are
- better for faster smaller targets.

Yes, this is very true. But the Hispano V actually
fired at virtually the same rate as the M2! And my
arguments is that when you get beyond a combined ROF
of about 50, P(1) is very similar in most practical
situations with fighter sized targets whether the ROF
is 50 or 500. What DOES change is P(x) where x >> 1.
That changes -a lot-

Anyway, I give up. This is like banging my head against
a wall.

XyZspineZyX
07-11-2003, 11:34 AM
WWMaxGunz wrote:
- Shaw did make a set of Lethality numbers for the
- guns listed so it's not complete bull although not a
- precise measure of all situations either.

I don't have the capabilities to take all situations
into account :-)

Seriously - doing that gets close to being a reimplementation
of FB, and then what we could do with is setting up
a whole load of attacks in FB and then ask Oleg the option
of hitting a magic button to change the weapon loadouts :-)

- What he does have to say that bears directly on this
- thread is what amounts to the observation that US
- designers built to counter German and Japanese
- fighters while the Germans built more to counter
- bombers.

But the British were the primary exponent of the
4 20mm cannon arrangement...

- He notes the problems of guns in the wings
- and and the problems of recoil slowing planes down

That's not something I've taken into account at all,
which really I should!

- as an especial problem with planes already going
- slow stalling out. Failure of a gun to fire on one
- side (jam) caused planes to yaw. Combine those two!
- And yet still the designs were made the way they
- were because they were effective. We did have the
- P-38's and weren't there other US planes with 20's
- in 1941 and before?

I am not sure about before. The P39 was designed around
the 37mm cannon, but with an eye on bomber intercepts.

The P61, A20G, F4U, P51/A36 (as Mustang 1A) F8F, F7F,
A1 Skyraider, and others all received 4 20mm fits at
various points,

- For sure if those cannon were
- better for the purposes planned then that's what
- would have been used.
-
-
- OTOH, while Browning made cannon as well as MG's

Interestingly I did some research. The M2 20mm was
a redesign of the original French Hispano, equivalent
in performance to the Hispano II, and the M3 similarly
with the Hispano V, but neither US cannon were as
reliable as the British ones, suffering the same jam
issues (to a lesser extent) that the British saw
in 1940. THis may well have influenced the decisions.

Also, interesting, the .60 proposed was a development
of captured MG151s

- cost in time, materials, tooling and money may have
- entered into the equation as there were LOTS of
- those guns made.

I think it was largely a logistics issue. And US
logistics were perhaps its strongest suit (German
logisitcs were dire).

- Shaw didn't have anything bad to say about the use
- of 50's in WWII US fighters. He didn't say they
- were stellar either.

My argument has been that the use of 4 20mm cannon
in the P47 would have given it about the same or
slightly better armament, with no great loss in
ability to land at least one shot on target. My bug
bear is that people think P(1) is greatly reduced by
having half the number of guns.

I think the P47 would have had more chance of blowing
up Tigers if it had got a 4 20mm loadout, though :-)

XyZspineZyX
07-11-2003, 05:48 PM
Given the disparity of the guns, I think that P(enough) would matter more than P(1) where the number of hits varies with the mission.