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GalexSedlex
03-14-2004, 06:34 AM
Hello Oleg and everyone,

Sorry to start another complaining topic about FMs.
I noticed that Spits Vb are very good... But the battle reports (especially from Clostemann, French Pilot) notice that it was completely surpassed by FW-190s...
May be I fly against to weak FW drivers, or maybe I'm too good (my bet is none are true), but the MkV eats them for breakfast.
Don't you guys thinks there is a problem with the spit ?
I wonder how the MkIX will be !
:-D
I am otherwise delighted with AEP and this minor glitch is not a real concern...
I just wanted to share my thought and know what other think.

Galex SedLex

GalexSedlex
03-14-2004, 06:34 AM
Hello Oleg and everyone,

Sorry to start another complaining topic about FMs.
I noticed that Spits Vb are very good... But the battle reports (especially from Clostemann, French Pilot) notice that it was completely surpassed by FW-190s...
May be I fly against to weak FW drivers, or maybe I'm too good (my bet is none are true), but the MkV eats them for breakfast.
Don't you guys thinks there is a problem with the spit ?
I wonder how the MkIX will be !
:-D
I am otherwise delighted with AEP and this minor glitch is not a real concern...
I just wanted to share my thought and know what other think.

Galex SedLex

warriorbear
03-14-2004, 06:50 AM
nice generic post.

knight

Hristo_
03-14-2004, 07:13 AM
The integral part of Spit FM are certain Spit drivers which seems to be greatly attracted to the type...

No matter how generous or not the FM is, they will always push it over the limit with regard to flying silly http://ubbxforums.ubi.com/infopop/emoticons/icon_wink.gif.

VW-IceFire
03-14-2004, 08:09 AM
I think its more a matter of many pilots just not being experienced and therefore competitive with the FW190. Oleg and others have posted some data now showing exactly how to outclimb a Spitfire, how to outpace a Spitfire, and how to beat one. Its the tried, true, and has been pointed out a thousand times by experienced WWII pilots and seasoned FB veterans. Always have speed or altitude to your advantage.

Many people take a German fighter, even a 109, and attempt to enter into turn fights with La's, Yak's, Spitfires, and any other highly capable turn fighter and then wonder why the rest of their team can't help them clear their tail or why they keep loosing fights to these planes. Inevitably it leads to the claims of overmodeling and bias...in the meantime I've watched as the same mistakes are made over and over.

If you are piloting a FW190 you typically have a couple of things to your advantage.

The first is your engine power and your speed...in shallow dives or in level flight the FW190 is fast. Use CEM to get the most of your engine (prop pitch and boost at opportune moments are important). A shallow dive will allow you to escape from most opponents except a P-47 or a La (which has superior short term dive acceleration). At higher speeds only a few planes still retain manuverability...particularly in the elevator.

The second is the massive firepower. With 4x20mm cannons and machine guns of two types you have enough firepower to disable an engine, blow off a wing, cripple the flight surfaces, and rake 20mm cannon shells across your target from stem to stern.

Now I don't have AEP but considering that most people believe the Spitfire to be a bit similar to a Yak and considering that the same tactics apply no matter what the target is you just have to be proficient at your plane. The FW190 is harder to fly than some other types when you aren't used to it...when you are you'll start to feel the other types just don't offer enough speed or raw firepower.

So at this limited, non-AEP perspective, I believe its the pilots you may be flying against rather than specifically the FM's. Good FW190 pilots will give Spitfire V's a real handful...watch out for the IX tho http://ubbxforums.ubi.com/infopop/emoticons/icon_biggrin.gif

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ucanfly
03-14-2004, 01:11 PM
I have a better time against Spits online rather than offline. The LFCW AI model is much more challenging to be against than a Yak3 , LA7, or P-51. Even when I try to climb out at 350 kph they catch up with me.If I try against four ACE AIs, I can out dive them and that is about it. The Yaks and Las are far easier offline than spit LFCW IMO as I can take four of them (Yak3s or LAs) on with relative ease using a 190A5.

I thimk this an Ai issue more than anything offline as I notice the SPIT LFCW almost climbs outta sight before the merge, and avoidance, climbing, diving, keeping speed up, etc. doesn't seem to work so far. Still trying to figure out best way to go on offensive as BnZ doesn't work if they're above you most of the time and can outclimb you in QMB neutral - advantage situation.

pinche_bolillo
03-14-2004, 01:55 PM
in aep in my opinion, the spifire mv V is cannon fodder. if the spitfire is shooting you down a lot and you are in a 190 then stop turn fighting w/ them. if you read any popular report on the 190 vs spit you will see that they felt the 190 was more maneouverable due to the fact that the 190 could dive away from the spitfire and also that the 190 had such a high rate of roll that it could split s away and the spitfire could not follow. no where in the report does it say that a 190 could out turn a spitfire.

one thing that has been bugging me about the spitfire though has been its lack of roll rate. the clip wing spit has a rate of roll very similar to the 190 from stall speed to 400 mph, havent seen this in the game though :O

p/s oleg do not respond to any of my posts, I am an idiot and I will drag you down to my level and then beat you with experience.

Jazz-Man
03-14-2004, 04:41 PM
...


The AI in this game will push aircraft beyond their limits. It has been like this Il2, and it is still like this AEP. AI planes are not the best way to judge the flight model of a particular aircraft. The best way to test reletive flight models is to do so online on a 2 person server.

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rangooon
03-14-2004, 04:56 PM
ola!

i read posts like these all the time which spout FM discrepancies as they pertain to a certain plane and/or plane set.

most of the time, i wonder how the "spouter" has configured his/or hers joystick.

seems likely to me that poor joystick settings result in lackluster performance and, as such, are an instigator of many of these posts.

just my opinion.

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HellToupee
03-14-2004, 05:49 PM
I fly the spit alot i fidn it very good tho, if the guy runs he usually gets away, in turn fights i find i catch up to them and they dont last long under a burst of the 20mms http://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif.

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SeaFireLIV
03-14-2004, 06:06 PM
I was wondering how long it would take before someone would complain about the Spitfire. Attempts to destroy it have begun already and most of Europe still hasn`t got AEP yet, so we can`t speak up for it. It`s a Brit plane dammit! Let us at least have our say! http://ubbxforums.ubi.com/infopop/emoticons/icon_frown.gif

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Soon... Very soon....

Bull_dog_
03-14-2004, 07:48 PM
I fly mostly allied aircraft, but I was flying online tonight in a server with historical aircraft...so it pitted G-2's and Fw A-5's against spit LfMk V's....

While I don't fly the Fw much, I've learned to fly it like the Jug and when I do it is very difficult for anyone to shoot it down...such was the case tonight.

The spitfires were no match...I was even able to get double kills twice...2 on 1. I'm sure there was some luck to it but I wasn't going against noobie pilots. The fight was below 3000 meters like most on line fights. I just kept my airspeed up...that was all I needed cause a spit can't catch a Fw. There wasn't too many on this server so I was able to extend before turning around and of course a Fw is deadly in a head on.

Problem is on-line, too many pilots want to completely kill their opponent and follow them into the sea. In real life it didn't happen that way. Self preservation was number one...no turn fighting for a Fw pilot and all was well. In real life, if the situation wasn't good then pilots chose not to engage...

Anyways, I like the spit and I think its modelled pretty close to right having flown it. Get on a server with historical planesets and jump in a Fw...fastest ride at low altitude and tear them up. Start turning with a spitfire and your dead meat...I don't care what kind of luftwaffe plane your in...it was the best turnfighter of the European Theater from 1941 on...so don't turn with it...

I can't out turn a zero in a yak-3 either...so I don't.

SAF_ginner
03-14-2004, 08:38 PM
[QUOTE]Originally posted by VW-IceFire:
I think its more a matter of many pilots just not being experienced and therefore competitive with the FW190. Oleg and others have posted some data now showing exactly how to outclimb a Spitfire, how to outpace a Spitfire, and how to beat one. Its the tried, true, and has been pointed out a thousand times by experienced WWII pilots and seasoned FB veterans. Always have speed or altitude to your advantage.

Many people take a German fighter, even a 109, and attempt to enter into turn fights with La's, Yak's, Spitfires, and any other highly capable turn fighter and then wonder why the rest of their team can't help them clear their tail or why they keep loosing fights to these planes. Inevitably it leads to the claims of overmodeling and bias...in the meantime I've watched as the same mistakes are made over and over.

If you are piloting a FW190 you typically have a couple of things to your advantage.

The first is your engine power and your speed...in shallow dives or in level flight the FW190 is fast. Use CEM to get the most of your engine (prop pitch and boost at opportune moments are important). A shallow dive will allow you to escape from most opponents except a P-47 or a La (which has superior short term dive acceleration). At higher speeds only a few planes still retain manuverability...particularly in the elevator.

The second is the massive firepower. With 4x20mm cannons and machine guns of two types you have enough firepower to disable an engine, blow off a wing, cripple the flight surfaces, and rake 20mm cannon shells across your target from stem to stern.

Now I don't have AEP but considering that most people believe the Spitfire to be a bit similar to a Yak and considering that the same tactics apply no matter what the target is you just have to be proficient at your plane. The FW190 is harder to fly than some other types when you aren't used to it...when you are you'll start to feel the other types just don't offer enough speed or raw firepower.

So at this limited, non-AEP perspective, I believe its the pilots you may be flying against rather than specifically the FM's. Good FW190 pilots will give Spitfire V's a real handful...watch out for the IX tho http://ubbxforums.ubi.com/infopop/emoticons/icon_biggrin.gif

http://ubbxforums.ubi.com/infopop/emoticons/icon_rolleyes.gif this guys... dont talk and show something online... i take spit you fw - and when you get one kill and i nine - you are still the winner

ucanfly
03-14-2004, 09:30 PM
I would like someone to show a track offline with no advantage in which you go 1 on 4 in a 190A5 against 4 ACE Spit LFCW (the non LF elliptical is much easier), without any cheats, especially hitting WEP prior to dot visibility, and start below 3000 m.

This is not a challenge, but a request. I have taken a couple out but feel lucky to escape alive from an offensive confrontation.

GalexSedlex
03-15-2004, 12:18 AM
All right, then !
Thanks every one for your opinions.
Got me to read the other FW-Spit posts...
Interresting indeed.
I was just wondering why...
Now I can tell it's because those FW drivers were 'flying slow and turning with me'
I guess that's why I was feeling the FM was 'too good' regarding Clostermann's writings.
Thanks for sharing your thoughts !

Galex SedLex

Hunde_3.JG51
03-15-2004, 12:52 AM
Me and my squad leader just did some side by side testing with the Spitfire and 190 (as Oleg suggested) concerning dive. The FW-190A-4 pulled away slightly from the Spitfire '41 in a prolonged dive which resulted in the controls coming off of the Spitfire. The difference was so slight that it was of no real advantage for the 190 with the Spit easily remaining within firing range. With the LF.V '42 there was no difference in dive at all. We will try more dive angles tomorrow.

What was really disturbing was that I was shallow diving away from the Spitfire LF. in the 190A-9 with more of an advantage than the A-4, but when I leveled out (after clearly pulling away from the Spitifre) and went into zoom climb at over 640+km/h IAS the Spitifre walked me down as if I was standing still and was easily within firing range in moments. We will probably record a track tomorrow as this seemed really off. We will evaluate it and see if it is worth sending to Oleg (along with dive tracks). Also, the ability of the Spitfire to hang on its prop is amazing and there is no stiffness of elevator even at critical dive speed (whether this is correct or not I don't know).

Before anyone gets too worked up, I'm only doing as Oleg asked in another thread. He suggested going online with another person and flying the 190 and Spit side by side and compare, then switch drivers. Thats what we did and the results were certainly interesting, but there is alot more to test.

*All tests done with radiator closed, max power (including WEP/Boost), and manual prop-pitch for 190.

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[This message was edited by Hunde_3.JG51 on Mon March 15 2004 at 12:10 AM.]

RAF74_Buzzsaw
03-15-2004, 01:36 AM
Salute

The problem with dives is not just the Spitfire, it's with all planes.

The P-47 should out dive pretty much anything, but it doesn't. It only gains an advantage at extreme speeds, which normally are not attainable at the heights aircraft usually fight.

Overall dive acceleration is too slow. Gravity does not seem to be taken into account as much as it should.

blabla0001
03-15-2004, 03:14 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by RAF74BuzzsawXO:
Salute

The problem with dives is not just the Spitfire, it's with all planes.

The P-47 should out dive pretty much anything, but it doesn't. It only gains an advantage at extreme speeds, which normally are not attainable at the heights aircraft usually fight.

Overall dive acceleration is too slow. Gravity does not seem to be taken into account as much as it should.<HR></BLOCKQUOTE>

That is the trend around here for certain people.
Simply target one plane type because it gives them trouble so it get's toned down without looking at the rest of the planes and their FM.

robban75
03-15-2004, 06:16 AM
Hunde, unfortunatelly the Fw 190A-9 still has a bugged climb. It's really no better in the climb than a Fw 190A-5. On my computer anyways. http://ubbxforums.ubi.com/images/smiley/16x16_smiley-sad.gif

In RL a diving D-9 could leave the Yak-9 and Yak-3 standing. To do this in FB you have to reach 900km/h IAS in order to increase separation from even the light Yak-3. http://ubbxforums.ubi.com/images/smiley/16x16_smiley-indifferent.gif

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When it comes to aircombat, I'd rather be lucky than good any day!

GregSM
03-15-2004, 07:01 AM
Hi all,


The FW 190 A4 I've got goes up to roughly 950 KPH TAS before it starts to break, while the Spitfire V LF CW makes 830.


Cheers,


Greg

WWMaxGunz
03-15-2004, 07:34 AM
In real, pilots did not go diving trying to see what speed their planes would break up at. Far sooner they would cut back unless chased with pretty certain death if they did cut back.

Some things about engines and pressure are no modelled too. I know this from professional pilots that leaving power high while doing some things about pitch would blow an engine but do not in the sim, those things involve putting heavy backpressure on the engine, going slow with too coarse a pitch and lots of throttle is one and somethings in dives is another. So gravity and mass against drag as importance, some is lost to being able to get extra engine thrust beyond where it should be seems to me to be a factor. Other long time and pro pilots write about prop bearings that would fail in dives that gamers put the planes to routinely.

If we treat the planes unrealistically and they take it then unreal results will happen.

With regard to FW's vs Spits online... the gunsight view of the FW makes deflection shooting harder than it should. BnZ requires deflection shooting. Deflection shooting is harder always than to park behind a plane and rattle away. Most players regardless of plane will get behind, stay there and rattle away. To do that requires flying co-speed with the target and that is not the way to stay long alive in a furball and especially against a plane with better low speed handling than yours. In plain, it's kind of dumb to do and even worse to complain about when you lose. As for using the statistics online or against the AI... just say you're ignorant and need to learn a lot.

This sim ain't perfect. Never will be. Learn to use what there is as it is and try, try, try to disengage your personal and nation images from those in the game! You'll enjoy it much more and maybe learn some good things in general.


Neal

JaBo_HH-BlackSheep
03-15-2004, 08:15 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by HellToupee:
I fly the spit alot i fidn it very good tho, if the guy runs he usually gets away, in turn fights i find i catch up to them and they dont last long under a burst of the 20mms http://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif.

http://lamppost.mine.nu/ahclan/files/sigs/spitwhiners1.jpg d<HR></BLOCKQUOTE>

tur, but the Spit last quite long under the burst of 4x20 ...

blabla0001
03-15-2004, 09:12 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by ToP_BlackSheep:
tur, but the Spit last quite long under the burst of 4x20 ...<HR></BLOCKQUOTE>

From where?
Dead six or something?

One hit in the spitfire's engine and it bursts into flames.

If you really are just a dead six shooter then aim for the cowl box on the left wing root.

And the Spitfire's wings snap off pretty good too if you come from above.

All this was tested with a Bf109 G2, so that's just one 20mm cannon instead of four.

faustnik
03-15-2004, 09:32 AM
Spitfires are more vunerable than most of the fighters in FB now. Every a/c seems to take more hits than before.

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JaBo_HH-BlackSheep
03-15-2004, 10:23 AM
ok i gave it a try offline and your right,

but spit has a quite crazy DM even shoting the outerwing will cause smoke out of the engine.

and since FB it's nearly impossible for FW to down a fighter with a snapshot. http://ubbxforums.ubi.com/infopop/emoticons/icon_frown.gif (4*20 schould do this job just fine http://ubbxforums.ubi.com/infopop/emoticons/icon_frown.gif )

Aaron_GT
03-15-2004, 11:13 AM
Buzzsaw wrote:
"The P-47 should out dive pretty much anything"

In some circumstances. You suggest it really only
outdives when at high speed. This sounds about
right. The P-47 has relatively poor powerloading,
but excellent aerodynamics. It has relatively low
drag per unit mass at high speed compared to
most planes in the game.

At low speed its lack of power loading will mean
that it doesn't accelerate as quickly in a dive
as some planes. If it enters the dive at high speed,
however, its aerodynamic advantages quickly
begin to dominate and it pulls away.

If the modelling on the Tempest V is correct it
should be a shade better than the P47 according
to the RAF. Reading between the lines of this
statement by the RAF on the basis by comparing
power loading, the Tempest probably has
similar high speed dive characteristics (relatively
low drag for size of plane) but better lower
speed dive characteristics due to slightly better
power loading (15% better more or less AFAIK).

With regard to Spits versus 190s - compare the
speed at which you enter the dive, and the power
loading of the planes at that altitude. It might
not be so far wrong.

Hunde_3.JG51
03-15-2004, 11:37 AM
Just to clarify.

I am not targeting the Spitfire, my tests are more to draw attention to problems with 190 or FB engine in genereal. Planes like the P-47, FW-190, and P-51 don't seem to have any useful dive advantage. This advantage was used to pull away from pursuers or to catch opponents. It has to do with acceleration and building speed quickly, not critical dive speed. I said a long time ago that the poor performance/attributes of the A-4 will lead to alot of arguments when the Spitfire V is released.

And I think with DM changes all structures are too tough. Actually thats not true, I like the tougher fuesalage structures but wings of all planes simply take too much damage now IMO. Others will likely disagree and thats fine. And I do agree that the Spitfire's engine may be the most vulnerable in the game.

And Robban it looks like you are right, the more time I spend with the A-9 the more I realize that its climb is still too low. It climbs like an A-5 despite having about 400 more hp and despite what it says in object viewer. Anyway the test we did last night will likely be sent to Oleg as it just looked silly as a plane going MUCH slower simply ran down the A-9 (with superior speed and energy) in an incredibly short period of time as soon as the nose goes above the horizon and into a climb.

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Gunner_361st
03-15-2004, 11:43 AM
Snapshots not working in the FW190 with 4x 20mm cannon? Hehe... They seem to work just fine for me. Whats important is just how many of your rounds hit, exactly where they hit, and what types of rounds hit.

If a bunch of HE rounds hit one relatively small area of the wing all at once, its a sure bet that wing is coming off. In turn, if only mostly armor piercing shells hit all over the plane, chances are you just make the plane swiss-cheese rather than chopping anything off. (Don't forget control cables, we got those modeled in to practically everything too now as well)

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GalexSedlex
03-15-2004, 12:11 PM
MaxGunz:

Hello !

Please note that i didn't try to say this game is not good or ahything like that.
To clarify: I think this game is Outstanding in every matter.
I was just curious about one particular game-fact in (as i thought) contradiction with Clostermann's writings.
But, be sure my friend, I really enjoy that game. No matter what my nationality maybe (neither brit nor german, tho).
I (very) keep in mind that this IS A GAME. Yes, it's outstanding. Yes it's almost incredibly beautiful. Yes we couldn't have dreamt it a few years ago. Yes, we see many guy taking this much too seriously. But I guarantee one thing: I'm having fun with this 'Entertainement' piece of software... And lots of it.

Hope you guys also have this fun.

Sincerely,

Galex SedLex

WWMaxGunz
03-15-2004, 12:48 PM
I am hoping the patch will change some things as possible. Just sent a track in to show how shell explosions inside a cockpit right close to pilot and rear gunner had no effect on either. And there was more than one of those in a single frontal pass.

My feeling is that crew are not flesh. ;^) Also that this is the biggest weakness in DM's I see in the game. If crew injuries due to explosions inside the cockpits plus on unarmored glass and skin just outside their positions were modelled then many planes would go down easier and we would not see people trying to cut wings or blow tails off in frustration. Well, less of those anyway.

Maybe as well the dive issues will change. I think there is less chance of that. It is not a question of what when a change is made but of how the change is to be made. How is it working wrong? The physics are supposed to be right within close limits. That is why I was saying that what I heard about engines may be the difference. But there are still conditions where the plane that won't win in the long run will be ahead in the start and keep up for a while in reality.


Neal

pinche_bolillo
03-15-2004, 04:30 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Aaron_GT:
Buzzsaw wrote:
"The P-47 should out dive pretty much anything"

In some circumstances. You suggest it really only
outdives when at high speed. This sounds about
right. The P-47 has relatively poor powerloading,
but excellent aerodynamics. It has relatively low
drag per unit mass at high speed compared to
most planes in the game.

At low speed its lack of power loading will mean
that it doesn't accelerate as quickly in a dive
as some planes. If it enters the dive at high speed,
however, its aerodynamic advantages quickly
begin to dominate and it pulls away.

If the modelling on the Tempest V is correct it
should be a shade better than the P47 according
to the RAF. Reading between the lines of this
statement by the RAF on the basis by comparing
power loading, the Tempest probably has
similar high speed dive characteristics (relatively
low drag for size of plane) but better lower
speed dive characteristics due to slightly better
power loading (15% better more or less AFAIK).

With regard to Spits versus 190s - compare the
speed at which you enter the dive, and the power
loading of the planes at that altitude. It might
not be so far wrong.<HR></BLOCKQUOTE>

I think buzzsaw has an interesting point. yes it is true that at low speed the P-47 did not have steller accelleration, however this is in level flight. when any aircraft dives its weight brings in a considerable advantage in terms of dive accelleration it is included in the forces that drive the a/c, gravity now becomes a source of accelleration.

Bull_dog_
03-15-2004, 05:34 PM
I'm so glad to see the energy model talked about...it is probably one of the weak points of the FM that doesn't get modelled... I think the high altitude modelling is pretty good but most wouldn't agree i think...

anyways as I was reading through the posts comparing spit mk V's to Fw's... it occurred to me that we might not be comparing proper aircraft...the spit that was so heavily dominated by Fw's was the hf V with full wings, 1941 version... once the wings were clipped, things were a little better and when the Lf verisons arrived on the scene they could hold their own with Fw's down low...they stayed in service until mid 1944 !

Just a guard against expectations... the Fw should not dominate the Lf series down low. The Hf MkV's without clipped wings should be pretty vulnerable to A-4's and A-5's and I still contend that spit mk V's are not a match for a well flown Fw... the Fw can choose their time and place and that is always the ultimate advantage. If an online player doesn't choose the time and place of the fight then so be it... they are just being an on line player ... I think fm's for fw's and spits are pretty close over all imho

pinche_bolillo
03-16-2004, 12:17 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Bull_dog_:
I'm so glad to see the energy model talked about...it is probably one of the weak points of the FM that doesn't get modelled... I think the high altitude modelling is pretty good but most wouldn't agree i think...

anyways as I was reading through the posts comparing spit mk V's to Fw's... it occurred to me that we might not be comparing proper aircraft...the spit that was so heavily dominated by Fw's was the hf V with full wings, 1941 version... once the wings were clipped, things were a little better and when the Lf verisons arrived on the scene they could hold their own with Fw's down low...they stayed in service until mid 1944 !

Just a guard against expectations... the Fw should not dominate the Lf series down low. The Hf MkV's without clipped wings should be pretty vulnerable to A-4's and A-5's and I still contend that spit mk V's are not a match for a well flown Fw... the Fw can choose their time and place and that is always the ultimate advantage. If an online player doesn't choose the time and place of the fight then so be it... they are just being an on line player ... I think fm's for fw's and spits are pretty close over all imho<HR></BLOCKQUOTE>

compair the roll rate for the spit mkv and mk v clippy to the naca chart. you will find that neither roll anywhere near what the chart says that they do. on the naca chart the clippy out rolls the 190 by a small margine from stall speed to about 400 kph and above that the 190 out rolls the clippy by a small margine up to the limit of the chart which is around 630 kph. so for all practical purposes the roll rates of the 190 and clippy are so close that they should have amost identicle roll performance.

Aaron_GT
03-16-2004, 10:28 AM
" think buzzsaw has an interesting point. yes it is true that at low speed the P-47 did not have steller accelleration, however this is in level flight. when any aircraft dives its weight brings in a considerable advantage in terms of dive accelleration it is included in the forces that drive the a/c, gravity now becomes a source of accelleration."

The weight itself (if drag was the same) wouldn't matter
at all. Big things don't drop faster _unless_ the drag per
unit mass is less.

If you are diving well under the maximum level speed
then the forces are along the direction of movement
are:

Engine thrust, T
Force due to gravity, sin(p).m.g where p is the dive angle
from the horizontal
and drag, D.

F=ma, so ma = T+sin(p).m.g -D
or
a=T/m + sin(a).g -D/m

If the plane was going at a steady speed below its maximum
before it was diving then T=D before this (p=0, a=0).

If we assume that to begin with the drag doesn't increase
much with speed or induced drag (i.e. remains relatively
constant) then we have. At lower speeds D will increase
more slowly with speed.

a = deltaT/m + sin(a).g

where deltaT is the increase in thrust that is applied
by throttling up the engine.

Thus the acceleration is proportional to the increase
in power applied,, which is related to the power loading,
plus what is there from gravity. Increased mass does
NOT give the plane any advantage (rather the reverse).

Now if the plane is at maximum level speed when
it enters the dive then deltaT is zero - the engine is
already putting in the most thrust it can at that speed.
Also D will change much more rapidly as the speed
increases, so we can't ignore it.

So we have
a = sin(p).g -(D(v1,m)-D(v0,m))/m

where D is a function of the speed (v) and mass (m).
v1-v0 is the difference in speeds over which we are
measuring the acceleration. (It's hard to represent
things in just ascii!)

The dependency of D on v is much greater than that on m,
so we can reduce it to

a = sin(p).g -(D(v1)-D(v0))/m.

So now the plane which is larger actually has an
advantage if its aerodynamics are clean for its
size over an increase in speed at the higher end.

In other words, if two planes enter a dive at cruise,
the one which has better power loading (or rather
potential to improve its power loading) wins. If a
plane can cruise well at lower power (e.g. P51) then
it has power loading in reserve to add into a dive.

But in the long term, the cleaner, larger plane will
tend to win once maximum power has been applied.

There are more factors involved, but those are the
main ones.

JG14_Josf
03-16-2004, 01:55 PM
What is the effect of weight on speed?

Picture a glider flying in ridge lift where this glider is not moving relative to the ground. Like a bird hovering over the side of a cliff.

For all practical purposes the glider is motionless.

The glider dumps ballast.

What happens to the glider?

Add an engine to the glider and at the same time add a higher relative wind velocity going up the ridge just enough to offset the increase in thrust.

The glider is now an airplane with an engine flying motionless relative to the earth.

The airplane dumps balast.

What happens to the airplane?

Aaron_GT
03-16-2004, 02:36 PM
Josf: the glider should
rise if ballast is dumped
as then lift exceeds weight.
However lift does not
contribute to speed to
forward airspeed, though.
It's not very relevant to
diving performance really
(except see below)

The part about bring
motionless relative to
the earth is irrelant as it
has motion relative to the
air, and gravity accelerates
you whether moving or not.

One thing missing from my
analysis above is the effect
of lift. At the moment the
plane enters the dive L=mg.
This lift will remain at
90 degrees to the long axis
at magnitude mg. Different
planes have different
centres of lift relative
to centre of gravity,
controls, etc, so its
going to account for.

Really you need figures
for this, induced drag
at velocity, drag, thrust
efficiency, at each velocity
etc and finally set up DEs
and solve for position. Not
simple!

I still think the general
principle is that power
loading matters
initially if you
enter a dive at cruise,
but aerodynamic efficiency
relative to gravitational
force (weight) makes the difference at high speed.

heywooood
03-16-2004, 03:40 PM
Airplanes really do evoke strong emotional responses from their fans. A sense of propriety
and of maternal protection of their characteristics that is primal in strength.
Do you have mathematical charts as proof of these claims?.. submit NACA charts from actual test pilots and the FM will be looked at again as Oleg has said - otherwise simmer down. Not diagrams and charts you or a friend made but real,solid data as was used originally by Maddox
programmers and I'm sure they will look at it.
k?

JG14_Josf
03-16-2004, 03:57 PM
Aaron_GT wrote:

"Josf: the glider should rise if ballast is dumped as then lift excees weight. However lift does not contribute to speed to forward airspeed, though."

I ask questions because it is important to me to keep my mind open.

I know this to be true:

Gravity contributes to foward thrust.

Not only does the glider go up but it also slows down when dumping ballast.

The pilot can control the tendency to climb as ballast is dumped by pitching the nose down. The glider will then go backwards relative to the ground.

In other words the glider is slower relative to the motion of the air and that is why this example is relavent to the question:

What is the effect of weight on speed?

Bull_dog_
03-16-2004, 05:55 PM
Weight has minimal impact on speed in level flight. In a vacuum, weight (mass) has no effect on the speed at which objects fall...ie a feather falls as fast as a marble.

In the atmosphere, there is drag cause by air. Heavy planes could compete with light planes where drag was low...at high altitude. Kinetic energy is greater in heavy objects hence the zoom climb...the top speed at a given dive angel will be largely a function of drag and weight...initial acceleration would be influenced by power to weight ratio however that effect would go away quickly.

If two planes had similar drag coefficients but one weighed 14,000 pounds and the other weighed 9,000 pounds and both entered a dive at a 15 degree dive angel starting at 300 mph...which one would be going faster 10 seconds later?

The heavier one would....if the dive continued, the heavier object would reach a higher speed than the lighter object at the same relative dive angel.

That is where energy modelling comes in...how fast was the accelaration? How long did a plane retain its speed? How does kinetic energy affect the zoom climb? and how fast is terminal velocity?

Yes there is a terminal velocity...by that I mean objects can only go so fast before drag stops their accelaration....A skydiver starting at 12,000 ft. will splat on the ground at the same speed as one who jumps from 15,000 ft assuming drag is equal....a heavier skydiver will splat at a higher terminal velocity than a lighter one with the same drag.

If a P-38 enters a dive at 12,000 ft. he will not experience compressability because the air is too dense and creates too much drag to allow him to reach a high enough terminal velocity...at 32,000 ft. the lightning pilot dare not enter a dive because the air is so thin that they will accelarate too fast and have compressibility problems as the air get thicker but speed is too high.

Heck I can't even remember what the topic was about other than it turned to energy modelling and I don't think that is FB strong suit ... not by a long shot ... and if we started debating flight models, we could throw all of them in there... there was a reason Bf109's split S'd on Lightnings at 25,000 ft and the lightning didn't follow and it wasn't because the 109 could dive faster...its light weight and slower dive acceleration allowed it to complete its loop before compressibility started where P-38's had lower compressibility speeds and accelerated too fast. Spits and Fw's could split S at high altitudes too.

WWMaxGunz
03-16-2004, 08:47 PM
Same plane, same dive, two different weights.

Until drag reaches thrust limit the accel will be determined by excess power to weight ratio. EP will be the same both times, weight differs.

Induced drag will be less than level flight by that sine dive angle fraction you gain mass x grav by. The dive angle isn't where the nose points is all.

Drag increases by square of speed difference unless the start speed is low enough the AOA has a significant induced drag, but once at cruise or faster the induced is low. Thing is that in a dive, drag picks up faster than speed.

So once drag &gt;= thrust you only have the force of weight (mass x gravity factored by dive angle) to pull you against the extra drag. Same plane, different weights you get the same drag.

Lastly, prop thrust efficiency drops off with speed. It is not linear. Accel from thrust gets less and less with speed but the force of weight remains constant.

These things affect dive performance. Maybe I missed something? I dunno. Got bad headaches today but I'm not terrible right now so I post.

I really think that someone like Blotto, Ugly Kid or Oryx to name 3 trained in this should be able to post the clearest meaning.


Neal

JG14_Josf
03-16-2004, 11:27 PM
Neal,

I don't know from where your experience originates, and can only guess that it is extensive.

I have flown in ridge lift. Weight is important for speed.

I know this, I have lived this fact.

In Hang Gliding, while that was a part of my life, we called it penetration.

I does not matter to me how many guys offer their expertise on this subject matter with numbers and equations, at least not until my experience is explained.

So far, even Oryx has not been able to accomplish this task.

I am thick, it comes with old age.

What I do find curious is that on this subject I have found others who confirm my understanding.

Perhaps Robert Shaw will suffice as a reference:

Fighter Combat

page 407

"When two fighters are similar in all respects except that one is heavier, the heavier aircraft will accelerate faster in a dive and, assuming structural considerations allow, will have a faster terminal velocity."

As far as the FW performance discussion goes I cannot say that I have any experience with how a real FW will perform against a Spitfire and despite my quotes from books reporting WWII combat pilots who flew a capture FW against Spitfires and how thier conclusions do not agree with the opinions of the 'experts' on this board, I can tell you for certain that I have personal experience with weight and speed.

My life has depended upon this relationship.

My tendency, despite the resolve to keep and open mind, is to go with Robert Shaw's take on this issue as refered above, since his clearly stated opinion agrees with my own.

Please continue to prove otherwise.

WWMaxGunz
03-17-2004, 12:46 AM
Of course more weight makes you go faster in a dive. Isn't that evident that I think so from the above?

The FORCE of your WEIGHT (mass x gravity) pulls you against drag from the air. However if the acceleration from your THRUST/MASS is greater than the acceleration of GRAVITY (appx 10m/s/s) times the sin of your dive angle then THRUST will dominate.

Straight down dive, your nose actually points farther so your wings don't pull you outward.

FORCE -- mass x gravity
FORCE -- thrust
FORCE -- drag

As long as mass x gravity + thrust &gt; drag, you accelerate. But thrust acceleration divides by mass while gravity acceleration is a constant.

If you start the dive slow enough then the same plane with less weight will accelerate quicker until the speed is up enough to negate the advantage of thrust/less mass.

Gee... why wouldn't this be evident in a glider?
I know! How much thrust does the glider have?

Suffice it to say that in a vertical dive in a powered prop plane the the speed picks up quick and I'd expect the same plane with more mass to pull ahead in less than a linear proportion to that extra mass since drag increases by appx the square of the speed increase. I'd also add that at very high speed there's the prop disk acting as a brake effect, still heavier will dive faster before long. If the planes start at high speed then the heavier will probably have the lead sooner and at top speed it would be from the instant of the start of the dive.

You should also remember to reread the forward that Robert Shaw wrote and take that in consideration. In fact, really spend some time thinking about that because he means it.

I've got a funny idea who Oleg might have meant about people who only know literature lyrics that want to discuss FM. It's not a matter of incantations but rather of physics best learned by experiments and observations (lab time) for everything read from books. At least it worked that way in my time, I graduated HS in 1975.


Neal

Aaron_GT
03-17-2004, 01:03 AM
Josf wrote:
"Gravity contributes to foward thrust."

Only if you are descending - potential energy is
converted into kinetic energy

Josf wrote:
"Not only does the glider go up but it also slows down when dumping ballast."

As the plane is climbing, and thus forward speed is
being converted partially into vertical speed (kinetic energy
is converted into potential energy).

Bull dog wrote:
"If two planes had similar drag coefficients but one weighed 14,000 pounds and the other weighed 9,000 pounds and both entered a dive at a 15 degree dive angel starting at 300 mph...which one would be going faster 10 seconds later?

The heavier one would."

On the whole this will be true, because for a spherical
body at least (as in Gallileo's experiments) for force
due to gravity is mg, which is p*(4/3)*pi*r^3 where p
is the density of the object, and the drag is proportional
to Cd4*pi*r^2 (assuming the wetted area to be the whole
surface area).

This is sort of my point.

But the complicating factor over dropping cannonballs
is the fact that powered aircraft add additional thrust
into the equation.

Aaron_GT
03-17-2004, 01:05 AM
"Until drag reaches thrust limit the accel will be determined by excess power to weight ratio. EP will be the same both times, weight differs."

Thanks Neal - so much more succinctly put then I managed!!!

Aaron_GT
03-17-2004, 01:30 AM
Anyway, getting back to the thing that sparked off this
part of the debate off, if you have a P47D at cruise
of, say, 200mph at about sea level, and a 109G at the
same. Both have about the same speed at sea level, so
I'll assume that at 200mph the drag is the same too.
Let's assume that the 109 needs half its horsepower
to stay there (say 800hp), and the P47 needs the same.

The 109's excess power available is about 800hp, and
for the P47 around 1300hp (depending on exact version)

The 109 weighs about 7000lbs, the P47 about 17000lbs.

So the excess power:weight on starting the dive for the
109 is about 0.11 hp/lb, and for the P47 it is about 0.07
hp/lb so the 109, from cruise, should accelerate faster
initially at sea level.

At maximum sea level speed the planes will be evenly
matched (the sea level max speeds are about the same,
and excess thrust is zero).

In a prolonged dive the 109's drag will increase more
rapidly at speeds about the max sea level speed as it is
a less clean design than that of the P47 - i..e in
prolonged dive the P47 will win.

Ok... now imagine we are at 20,000 feet at 200mph IAS.
The 109's engine is now putting out only 800hp max perhaps.
Assume it still takes 50% of this power to keep it at 200
IAS, and we have an excess power of 400hp. The P47's
engine retains power much better, so let's assume it is
still developing 1700hp, but that it still takes about 400hp
to keep the plane in the air at 200 IAS. The excess power
for the P47 is now 1300hp.

So the excess power:weight for the 109 is 0.06 hp/lb, and
for the P47 it is 0.08 hp/lb. At 20,000 feet the P47's
power loading is better - it can dive better initially. But
NOT because of its size, but because of the excellent engine.

At maximum speed for the 109G at 20,000 feet the P47
still has a little power in reserve, and will always win in
a long dive due to its cleaner aerodynamics.

These figures are guesswork, of course, but give the general
impression.

Now when people do a dive test of an La7 and P47
and complain the P47 doesn't win, you have to look at

(1) What speed the dive was entered at
(2) At what altitude it was entered at
(3) How long the dive was sustained for

If it was at cruise, and low, the La7 (or 109 or whatever)
winning initially is likely to be correct. If sustained the
P47 should ultimately gain, but rather slowly at low
altitude. Ditto if entered at high speed.

At 20,000 feet, the P47 should probably pull ahead
from the outset against most planes.

So when you read from pilots about the diving ability
of a plane being excellent, you have to look at the
altitudes and speed regimes at which they typically
entered those dives.

With regard to the Tempest V, it had about the
same engine power as all but the latest P47Ds
or Ms, and was about 25% lighter, and around
the same speed as the D-22, D-27, etc. Thus
at lower altitudes it has better power loading
that the P47, and fairly similar aerodynamics,
hence it should be no surprise that low down
it should beat the P47, and probably largely
hold onto that lead. Above 20,000 feet the
Tempest's engine began to lose power against
the P47 somewhat, so at 30,000 feet I'd
except the P47 to win. Dive performance all
depends, really.

JG14_Josf
03-17-2004, 01:33 AM
Neal,

Why must you resort to insults?

Please manage your temper with more care.

If you continue with this type of aggrivating response I will have to call in a moderator...Tully....Oh Tully! http://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif

Back to the powered airplane that is parked in ridge lift; what happens when ballast is dropped and the pilot controls all vertical movement?
What happens if the powered aircraft does not add any additional power from the engine?

In this scenario the weight of the plane is decreasing while the power from the engine remains constant.

Does the plane move forward or backwards relative to the ground? Remember the pilot controls any vertical movement.

Please educate me, if this is possible, sans the insults, please.

Fighter Combat
by Robert Shaw

page184

"The following episode, found in Thunderbolt! by the World War II USAAF ace Robert S. Johnson, is one of the best examples available of the use of energy tactics (diving extension/pitch-back) to defeat a double-superior opponent. The encounter described is a mock combat engagement over England between Johnson (P-47C) and an unidentified RAF pilot in a new Spitfire IX. the Spitfire had about a 25 percent better power loading and nearly a 25 percent lower wing loading. The Thunderbolt's only perofrmance advantages were faster top speed, greater acceleration in a dive (because of the P-47's heavier weight and higher density), and better roll performance.)

Get the book "Fighter Combat"

If you are 'into' fighter combat and if you like to read then this book is a solid investment.

Purzel
03-17-2004, 03:51 AM
Not that this would be an educated statement or something, but I always felt that the e-modelling was the cause for most whines or problems IL-2 related.

Of course you get problems when turning with better turning opponents, but when you have an energy advantage and cannot make use of it because the other plane _turns_ better than theres something wrong.

Im talking of ppl in a biplane staying behind my FW although I had more speed when I "overshot". That just cannot be, I think I should have been out of gun-range for the most part of the fight, but I couldnt force this. And I could not keep my energy advantage while staying within 10nm of the biplane. I mean: I was (seemingly) much faster and much heavier and had much more hp. In a steep climb I should be out of range in a heartbeat, right? Well, I'm not.

Two days ago an P38 advanced my Ta152 from behind, he was faster. After hitting me but not crippling me he zoomed up. Heavy plane, fast, zooming up. I got him while still zooming up with some 30mm hits.

Somehow the TnB planes do ahve certain advantages going in the energy-model.

I know, ppl are going to say: "stop whining and learn to E-fight."

In other online-sims I manage to do just that. It should be possible to keep your advantage, if nothing unexpected happens, like his buddy coming in from above.

Well, we'll see if the modelling will change...

Aaron_GT
03-17-2004, 04:50 AM
"Does the plane move forward or backwards relative to the ground? Remember the pilot controls any vertical movement.
"

Actually the pilot does not control any vertical movement,
he may exert an influence over it.

As the ballast is dropped then if the pilot puts the nose
of the plane down he can translate some of the newly
acquired vertical movement due to a sudden excess of lift
into some forward motion, at the expense of increasing
drag due to the control forces required to do so. In a
sense it's a bit like tacking in a yacht.

JG14_Josf
03-17-2004, 08:43 AM
Aaron-GT,

So does the plane move forward or backward relative to the ground?

My experience with Gliders is such that the non engine powered plane will back-up relative to the ground as the Ballast is dumped out of the glider parked in ridge lift.

Since things are held constant and the ground serves as a reference this example illustrates to me that gravity or specifically the amount of weight a plane carries will determine, to some extent, the speed a plane travels through the air. Since the ridge must have an upward component in order for the glider to stay motionless relative to the ground this indicates that the weight/speed relationship is limited to flight assisited by gravity or in other words the forward component of thrust that is added by weight occurs in dives.

If that is saying the same thing as what a yacht does while tacking?

Does the addition of engine thrust cause the same glider situation described above to allow the plane to move foward relative to the ground as ballast is dumped even though no additional engine thrust is added while the ballast is dumped?

If so then where does this additional trust come from and why is it greater than the thrust lost by the glider?

My experience tells me that the glider hovering in ridge lift will not be able to maitain a fixed spot on the ridge relative to the ground as ballast is dumped. The Glider will back up if altitude is maintained.

Are you saying that this is due to an increase in drag due to control surface deflection?

If the nose is pitched down relative to the wind as the pilot controls vertical movement then isn't the wing decreasing the angle of attack relative to the wind and therefore unloading induced drag, shouldn't the plane then move forward as Ballast is dumped? Doesn't induced drag increase as a wing increases angle of attack relative to the wind?



In this ridge lift example the wind is a constant speed going up a slope, it does not change in this hypothetical example. Such lift can be found comming off the ocean at Torrey Pines California.

WWMaxGunz
03-17-2004, 09:49 AM
"Why must you resort to insults?"

Why do you persist in being obtuse?

"Please manage your temper with more care."

Temper?

"If you continue with this type of aggrivating response I will have to call in a moderator...Tully....Oh Tully! http://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif "

Go for it.

"Back to the powered airplane that is parked in ridge lift; what happens when ballast is dropped and the pilot controls all vertical movement?
What happens if the powered aircraft does not add any additional power from the engine?"

A) Ballast dropped = constant
B) Pilot controls all vertical movement = variable

What happens varies with pilot input.

"In this scenario the weight of the plane is decreasing while the power from the engine remains constant.

Does the plane move forward or backwards relative to the ground? Remember the pilot controls any vertical movement."

With the pilot controlling the movement this comes down to the pilot, don't it?"

"Please educate me, if this is possible, sans the insults, please."

If all you do is lose the weight then the plane rises.

That has NOTHING to do with initial acceleration going into a dive. In the beginning of your scenario the plane has reached terminal speed for the dive angle and thrust. Accel is ZERO. Go back and don't just read what I wrote but actually work out some pictures. Better yet, get an AE type to write a long explanation with examples. It's been done on thise forum while you were active in the threads back what, a year and a half ago?

"Fighter Combat
by Robert Shaw

page184

"The following episode, found in Thunderbolt! by the World War II USAAF ace Robert S. Johnson, is one of the best examples available of the use of energy tactics (diving extension/pitch-back) to defeat a double-superior opponent. The encounter described is a mock combat engagement over England between Johnson (P-47C) and an unidentified RAF pilot in a new Spitfire IX. the Spitfire had about a 25 percent better power loading and nearly a 25 percent lower wing loading. The Thunderbolt's only perofrmance advantages were faster top speed, greater acceleration in a dive (because of the P-47's heavier weight and higher density), and better roll performance.)

Get the book "Fighter Combat"

If you are 'into' fighter combat and if you like to read then this book is a solid investment."

Got my copy back in 1998 and read all parts pertaining to prop AC and combat in them. Lot of reading. I also worked through the examples, graphs and formulae given to make sure I understood HOW they worked and not just WHAT was said.

How else would I know to tell you to read the Forward of the same book? TWICE and now THREE TIMES! Actually, the chapter is named Preface so maybe that threw you?

pg xiii in my copy, the last paragraph... read it carefully. Throwing out general quotes and expecting them to cover every situation falls squarely into the category of unqualified absolutes. Some examples of qualifiers are; mostly, usually, probably, not always (as opposed to always and never that Shaw considers may only be oversights), and specifying conditions as far as you can be sure of when you want to be more definite.

Treating quotes like formal rules for a board game gets you nowhere real fast and prevents you from actually understanding jack. It's worse than cookbook, just about as limited unless it's cookbook followed by someone who can't conceive of varying the formula. If you find that insulting then it's your problem, I'm just commenting on your approach which hasn't changed a whit despite very many people, some with degrees in the subject, trying to make explanations while for your part there's quotes that only loosely cover the matter. Maybe you're right and the actual professionals are wrong? Or maybe you should take heed and change your tactics of understanding?
Quotes require sense and a view to apply to real world events, not just be thrown about without any view, understanding or opinion attached. When I ask for yours, you say you have none which leads to the question of why bother throwing out the quotes? If you have a question based on them then you must have some idea of what they mean and how they apply, ie a view, an understanding as it is, an opinion. So don't snow me.


Neal

JG14_Josf
03-17-2004, 10:16 AM
So, does the plane go backward or foward or stand motionless relative to the ground?

Do you mean to say that I am stupid? (http://www.m-w.com/cgi-bin/dictionary?book=Dictionary&va=obtuse) http://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif

I don't see what is so hard about answering my question. Can I word the question to be less confusing?

Do you not see any relevance between this subject on this post and my question?

Does the Spit dive better than the FW190 in the game?

Did the Spit dive better than the FW190 in reality?

Does weight increase dive acceleration?

Is the FW190 heavier than the Spit?

Does the FW190 have higher thrust than the Spit?



The War Diary of Hauptmann Helmut Lipfert

page 31

"But I was so furious that scarcely anything could have prevented me from diving after him, especially since I knew that my machine was heavier than his and that I could certainly overtake him."

WWMaxGunz
03-17-2004, 10:52 AM
You have the answers. Just not in cookbook form.

Even your quote from Lipfert should be a clue as he used the word overtake.

What you see in the sim depends on conditions and piloting. There is not a dive button where each plane executes a perfect dive and the heavy one automatically goes instantly fastest.

I'm not going to give you a quote from me that you can apply to all situations because nothing so simple fits all situations. It's silly to try. You think I'm silly? Find someone else.

Physics is not a court with lawyers playing word games with witnesses to determine some version of truth to suit their needs.


Neal

crazyivan1970
03-17-2004, 11:14 AM
I see smoke, but no fire yet... http://ubbxforums.ubi.com/infopop/emoticons/icon_biggrin.gif

Play nice boyz

V!
Regards,

http://blitzpigs.com/forum/images/smiles/smokin.gif

VFC*Crazyivan aka VFC*HOST

http://www.rmutt.netfirms.com/coop-ivan.jpg

http://www.rmutt.netfirms.com/vfc/home.htm

Kozhedub: In combat potential, the Yak-3, La-7 and La-9 fighters were indisputably superior to the Bf-109s and Fw-190s. But, as they say, no matter how good the violin may be, much depends on the violinist. I always felt respect for an enemy pilot whose plane I failed to down.

Bull_dog_
03-17-2004, 11:25 AM
In situations like this I am reminded that words do, in fact, have absolute meanings and that I do, in fact, believe in an objective reality.

A heavy plane does dive faster than a light plane all other things held equal. It did in WWII and it does now...but not always in the Cyber world since that is a subjective reality created by Oleg Maddox and is not subject to the laws of physics but rather by a human's ability to mimic those laws through binary code.

JG14_Josf
03-17-2004, 11:39 AM
Neal,

Strawman (http://www.m-w.com/cgi-bin/dictionary)arguments aside, my question is germane to this topic.

If you are unable or unwilling to answer the question then is it possible for you to explain the reason for you responses.

What is the effect of weight on dive performance that can be shown with clarity by the powered plane flying in ridge lift; does the plane move forward or back relative to the ground and therefore accelerate or decelerate relative to the constant up draft as ballast unloads?

Clearly a force changes with changes in weight so as to allow a glider to maintain airspeed in ridge lift. I trust you are not inclined to argue otherwise. As ballast is dropped the glider will be less capable of maintaining airspeed. It has been reported that gliders are not powered planes and that when the thrust of an engine is considered into the physical situation of flight then dive performance is also different. For this reason my situation with the glider that does dive faster with more weight now includes a force of engine thrust. It seems clear to me that since engine thrust does not change simply because the plane drops weight then the powered aircraft in ridge lift will also move back relative to the ground as ballast is dumped and therefore the powered aircraft will decelerate relative to the constant wind as the aircraft becomes lighter.

If that is not true, if a powered aircraft does not decelerate relative to the flow of air due to the loss of weight then this fact would be nice to know and I can move on to try and figure out why this occurs.

I find it difficult to proceed in my effort to understand the situation until this point is made clear.

If you are unable or unwilling to answer the question then why post a response? Why post an insulting response? Why post a response that avoids the question? Why do you create a Straw Man?

Who are you to determine my perspective? If your perspective is that this discussion is somehow analogous to 'a court' then does your perception reign supreme and does your perception override my own?

I assure you that my perception is not argumentative. I want to understand the effects of weight on speed. An answer to my question will move me along in that regard. That is why I ask the question.

How convenient it is for you to decide for me what are my motives in this discussion when your version of my motives are so easy to confute.

I must admit however that a part of my motivation for posting on these boards is a general desire to improve my writing ability.

Perhaps you see this as being argumentative.

My motive remains to understand the effect of weight on speed and therefore what is going on with the Spitfire flight model in this game relative to the FW190.

clint-ruin
03-17-2004, 11:45 AM
Related reading, can't really be bothered getting into an in-deep physics discussion, but this might help some of the participants. One second on google..

http://www.grc.nasa.gov/WWW/K-12/airplane/induced.html

http://www.csulb.edu/~gordon/valles.html

Weight is the force with which a planet's gravity attracts another mass:


W=mg = D

where W=weight

m=mass

g=acceleration of gravity and
http://www.csulb.edu/~gordon/drag1.gif


Where:

D=drag

http://www.csulb.edu/~gordon/rho.gif =atmospheric density

v=velocity

S=cross-sectional area

cd =drag coefficient, an empirically determined, dimensionless number, which relates to the shape of the object.


http://www.quantumscientific.com/balldrop.html

Explanation:
Gravity causes objects to accelerate towards the ground. The equation that governs the motion is as follows:

Force = Mass x Acceleration (Newton's Law)

Acceleration = Force / Mass

The force acting on the ball is WEIGHT, thus,

Acceleration = Weight / Mass = (Mass x G) / Mass = G = 9.8 m/sec‚¬≤

The mathematics shows that the acceleration in "independent" of the object's mass (or weight). As a result, for each second both balls fall, they gain the same amount of speed. If the speed of both balls is equal, they will travel the same distance for a given amount of time. Since they are falling the same distance, it will take the same amount of time for each to hit the ground.

This experiment can be expanded by using a basketball and a beach ball. Repeat the expeiment and see which one hits the ground first. Depending on the mass of the beach ball, the basketball will probably be the first to hit. Why? Doesn't gravity accelerate all objects equally? In this case, the drag acting on the beach ball comes into play. The drag force opposes the gravitational force (weight) as the beach ball falls and the resulting acceleration is lower. The same equations used above can be expanded to mathematically prove this.

Force = Mass x Acceleration

Acceleration = Force / Mass

Force = Weight - Drag

Thus,

Acceleration = (Weight - Drag) / Mass

Since the drag is more significant relative to the weight of the beach ball, the acceleration is less. The use of a balloon makes the effect even more significant.


edit: keep forgetting to paste bits in, sorry if you read this before the .gif equations and last italicised paragraph was added

http://home.iprimus.com.au/djgwen/fb/leninkoba.jpg

JG14_Josf
03-17-2004, 11:49 AM
crazyivan1970,

If you can point out where my posting has warranted these insulting responses then I can adjust my future postings to avoid a repeat occurance.

JG5_UnKle
03-17-2004, 11:52 AM
Purzel I agree. For a long time now and with extensive testing within our squad we have come to the same overall conclusion.

We fly a lot od VVS/UK/US kit as aggressors and find it extremely useful and enlightening. WRT the 190 (A4) vs Spit VB's I think you have to be a pretty dumb Spit driver to not kill a 190 in a Co-E fight.

With a 1500M advantage you can BnZ the spit forever and a day, you just might not kill him http://ubbxforums.ubi.com/infopop/emoticons/icon_wink.gif but you can do that in any a/c.

If you start Co-E with a Spit - what will you do? Extend maybe? So great, here we are extending away at 400 Kph.

If you are a dumb spit driver you will follow the 190.
If you are smart - you will climb.

So you end up in your 190 with separation and some Alt if you climbed, and the Spit has spent his time following you (dumb - he's been flat out running - lower energy and lower alt) then all you do is an oblique vertical turn and go head-on or set up your BnZ.

Thing is, if the Spit pilot spent his time climbing you are now heading towards a problem. You bleed loads of energy in the 190 just turning round to head back towards him, he's higher than you. If you try and climb up to him you just won't manage it if he keeps climbing - his sustained climb is better than yours. If you build up speed and try and zoom up to him you will find that doesn't help either.

If you try and extend and think Ah-ha! I will climb to 6000M where my Wurger is surely faster and can climb better? Think not :
http://homepage.ntlworld.com/victoria.stevens/190vspit_rocalt.gif

Look how the max Rate Of Climb for the spit way exceeds the 190, especially above 6000M! So if you are high - he would just climb up if he had any sense.

If you managed to get higher you MUST climb with a higher airspeed as he climbs much better than you at lower speeds. So a slow spiral climb that might work in the G-2 will not work in the 190 - understandable. Take a look:
http://homepage.ntlworld.com/victoria.stevens/190vspit_roczoom.gif

You can see at 250 Kph your climb rates are roughly equal (OK this is at zero alt) and at altitude it only gets worse :
http://homepage.ntlworld.com/victoria.stevens/190vspit_roc.gif

So a lot of it comes down to energy bleed.

You bleed more energy moving for a shot in the 190. Also you overheat much quicker so you can't apply 110% power as long as the Spit can.

The spit can pitch up after you at low speed and low AoA which is OK, but he can hang on his prop and shoot at you, (negating your zoom climb advantage) with no problems of Torque or P-Factor as they are not modelled http://ubbxforums.ubi.com/images/smiley/16x16_smiley-indifferent.gif

Anyway, long post - sorry guys. But in this case it is a mix of Pilot skill, FB Physics engine and initial situation.

If you meet a Co-E Spitfire flown by a good pilot and you are in a 190 A-4 you better hope he screws up. http://ubbxforums.ubi.com/images/smiley/blink.gif

http://homepage.ntlworld.com/victoria.stevens/jg5_logo.jpg

faustnik
03-17-2004, 12:28 PM
Of course the one ace-in-the-hole us 190 drivers have is the option to go home. http://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif Didn't Sun Tsu say to avoid a fight when you don't have a position of advantage?

Anyway, great post Uncle. You outlined our 190 climb issue very well. It's too bad you just get a bunch of garbage answers labeling you a whiner in rebuttal. http://ubbxforums.ubi.com/images/smiley/16x16_smiley-indifferent.gif

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www.7Jg77.com (http://www.7jg77.com)
CWoS FB forum. More Cheese, Less Whine. (http://www.acompletewasteofspace.com/forum/viewforum.php?f=25)

JG14_Josf
03-17-2004, 12:40 PM
Weight effect on descent performance (http://flighttest.navair.navy.mil/unrestricted/FTM108/c8.pdf)

"To fly a the same L/DMax (same descent angle) at a higher gross weight, the flight path airspeed increases and the rate of descent increases. At the higher airspeed for the higher gross weight, the increase in drag is offset by the increased weight component along the flight path."

Thanks all.

I think the picture is becoming clear.

But I am running out of time, chores must be done.

In short Ps or P sub s is normalized by dividing weight.
Weight drags the plane down.

Get it?

In the imortal words of the Governor.

"I'll be back"

JG5_UnKle
03-17-2004, 02:24 PM
LOL faustnik - what more can a poor luftwhiner do eh ? http://ubbxforums.ubi.com/images/smiley/10.gif

http://homepage.ntlworld.com/victoria.stevens/jg5_logo.jpg

Aaron_GT
03-17-2004, 02:26 PM
Just to throw more stuff
into the mix:

as clint says:
a=w/m - d/m

w/m is g, so a=g-d/m

For spheres of the same cd
using a wetted area of the
sphere's surface and of the
same dEensity we basically
get

a=g-k/r

where k is a constant

so two with two objects
falling unpowered then
of the same shape and
density the larger one
accelerates more.

With planes we have
different densities, cd,
variation of cd with speed,
other aerodynamic
considerations, plus thrust
so much more complex

With regard to the glider,
it will rise as the mass
is dropped as lift
exceeds weight, gaining
potential energy. Since
energy must be conserved
then kinetic energy must
be reduced, hence forward
speed is lost. If the pilot
tries to keep the plane
level then the kinetic
energy loss will be less
but not zero as drag will
have to be generated by
the control surfaces to
resist the tendency to rise.

The energy lost by dropping
ballast is probably less
relevant, perhaps. It isn't
that so much as resisting
the tendency to climb that
is.

JG14_Josf
03-17-2004, 02:43 PM
I understand that my brain may not be as sharp as others and in fact my brain may resemble a marble more so than a tack, but this subject has brewed within the limited confines of my electro-chemical pathways for such a great length of time that I now recognize a pattern that makes sense.

Height and speed alone do not describe enough information for the fighter pilot as these factors are static. At a given point in space and time a plane can be said to contain x amount of energy derived from the altitude times the speed of the plane.

What is needed is a reference to compare this factor of energy toward a future energy state; this is accomplished by dividing or normalizing the energy factor by weight.

The result is a number that represents maneuvering potential.

I have racked my brain for literally years in an effort to see this relationship for what it is and not just as jargon or dogma and numbers.

As the old saying goes: You can lead a horse to water but you can't make him drink.

Weight drags a plane down.

Adding more weight reduces maneuvering potential, but more specifically; adding weight lessens the ability a plane has at any given time during flight to gain more total energy.

Here is where the problem stumped my poor capability to deduce the complex relationship.

A heavy plane will dive faster than a light plane.

A heavy plane will bleed energy faster than a light plane.

Those two statements confounded my understanding as they appeared to contradict each other.

Now it seems clear to me that those two statements are one and the same.

Altitude is energy.

The heavy plane will bleed altutude energy faster than the light plane.

The more weight added to a plane the greater capacity that plane will have to bleed altitude energy.

And for that same reason the plane gaining in weight also gains in dive acceleration.

Clear understanding or greater confusion?

If this understanding is correct and if the IL2 flight model does not afford a heavy plane a faster capacity to dump altitude energy, even if the same penalty is not applied to the heavy plane resulting in a penalty for the heavy plane on the way back up, then the game is missing a physical relationship that does exist and did drive tactics.

Put another way; weight kills lift, lift maintains altitude, dive speed is the absence of lift and altitude.

So what happens when a plane is both heavy and produces a lot of thrust?

Fw 190 in Combat
by Alfred Price
Unsolicited Testimonials
page 51
"The Fw 190 is faster than the Spitfire IX in a dive, particularly during the initial stage. This superiority is not so marked as with the Spitfire VB."

JG14_Josf
03-17-2004, 03:22 PM
Please forgive my rambling on and off topic.

It makes very much more sense as this understanding connects the previously dead ended pathways in my thinking.

Sustained turn techniques work or should work in the real world because of this energy/speed/altitude relative relationship.

Fighter Combat by Robert Shaw:

One-versus-One Maneuvering, Dissimilar Aircraft
Low versus High Wing Loading with Similar T/W

page 179

"Because of the T/W equivalence, the climbing extension/pitch-back tactics described earlier generally are not viable. This method is based on exploiting a climb-rate superiority, which does not exist in this scenario. In order for the high-wing-loaded fighter pilot to gain an energy advantage where one does not exist initially, he must either increase energy faster than the opponent (which may be done by exploiting superior diving acceleration and high-speed energy addition rate in a diving extension), or induce the bogey to bleed energy at a faster rate (which may be accomplished by sustained-turn techniques)"

Note the words: exploiting superior diving acceleration and high-speed energy addition rate in a diving extension

Specifically note the word: High-speed energy addition rate

Not to be confused with total energy addition rate.

Sustained turn techniques work because the employer of the technique exploits the opponent.

This can only occur if the opponent takes the bait.

If the opponent does not follow the dive and instead chooses to keep a total energy advantage by staying higher, if the opponent choosed higher instead of faster then the sustained turn cannot work, instead the sustained turn becomes a simple diving extension. End of fight.

It is when the lighter fighter dives to catch the heavy fighter that the sustained turn technique starts to work.

The heavy fighter is gaining total energy relative to the lighter fighter hence the words: exploit superior high-speed energy addition rate. The lighter fighter dumps just as much altitude but doesn't gain as much speed.

The sustained turn technique then goes on to bait the lighter better turning opponent into pulling lead and burning massive amounts of energy. The lighter plane does not realize that the heavy plane has built up more total energy in the dive and the ligher plane does not realize that the heavy plane is not burning energy at as high a rate as the ligher plane when the lighter plane goes for the angles.
The ligher plane is looking for that shot pulling massive g's all the while the heavy plane is holding back and maintaining a higher total energy state.

This scenario cannot happen if the heavy plane does not have a dive acceleration advantage.

This scenario cannot happen if the lighter plane sports a much lower energy loss rate even during much higher G loads.

A heavy plane that does not have good dive acceleration but does have a high energy loss rate is like not having your cake and not be able to eat it too.

Energy tactics won't work.

crazyivan1970
03-17-2004, 04:14 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by JG14_Josf:
crazyivan1970,

If you can point out where my posting has warranted these insulting responses then I can adjust my future postings to avoid a repeat occurance.<HR></BLOCKQUOTE>

Josf, where in my post i pointed to you sir http://ubbxforums.ubi.com/images/smiley/16x16_smiley-wink.gif Just making an observation, that`s all. Been around long enough ya know http://ubbxforums.ubi.com/images/smiley/10.gif

V!
Regards,

http://blitzpigs.com/forum/images/smiles/smokin.gif

VFC*Crazyivan aka VFC*HOST

http://www.rmutt.netfirms.com/coop-ivan.jpg

http://www.rmutt.netfirms.com/vfc/home.htm

Kozhedub: In combat potential, the Yak-3, La-7 and La-9 fighters were indisputably superior to the Bf-109s and Fw-190s. But, as they say, no matter how good the violin may be, much depends on the violinist. I always felt respect for an enemy pilot whose plane I failed to down.

JG14_Josf
03-17-2004, 05:06 PM
Crazyivan,

Thanks http://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif

Joe

RAF74_Buzzsaw
03-17-2004, 08:08 PM
Salute

I would say that JG14 Josef and JG5 Unkle have summed it up very well.

Because the physics model of the game does not seem to take into account the effect of greater mass, both in dive acceleration, and in zoom climb, we have a situation whereby aircraft such as the 190A or P-47D lose a significant advantage which they enjoyed in real life.

Now whether that issue can or will be addressed by Oleg is a question. If the physics engine of the game cannot be modified to take this into account, then I guess large heavy aircraft will have to deal with the disadvantage.

There is one thing which probably should be done, that being that the early 190's climbrates should be improved to Western based 190 standards. Ie. 1.42 ata.

faustnik
03-17-2004, 08:14 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by RAF74BuzzsawXO:
There is one thing which probably should be done, that being that the early 190's climbrates should be improved to Western based 190 standards. Ie. 1.42 ata.<HR></BLOCKQUOTE>

http://ubbxforums.ubi.com/images/smiley/11.gif

Thanks Buzzsaw. You really do want realism! I take back every bad thing I ever posted about you. http://ubbxforums.ubi.com/images/smiley/16x16_smiley-very-happy.gif

And just so you know I agree with "the Spit ain't broke, so don't fix it".
Spit as Aces Scapegoat Thread (http://acompletewasteofspace.com/forum/viewtopic.php?t=18061)

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WUAF_Boxer
03-17-2004, 09:49 PM
I havent read every post but i just wanted to say that I have no problem shooting down spits in any 190. If flown correctly the 190 in FB can be virtually untouchable. In level flight at sea level the A4 is still a good 40 kph faster than the LF. 190 justs needs better climb and everything would be perfect imho.

Magister__Ludi
03-17-2004, 10:06 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by RAF74BuzzsawXO:

Because the physics model of the game does not seem to take into account the effect of greater mass, both in dive acceleration, and in zoom climb, we have a situation whereby aircraft such as the 190A or P-47D lose a significant advantage which they enjoyed in real life.

<HR></BLOCKQUOTE>


We've been here a thousand times. A plane with better powerloading accelerates better in a dive up to max speed in level flight, then the heavier plane accelerates faster. This is a physical fact and Il2 reflects it very well, much better than any other sim.

If you want to test it, try in QMB with a Jug and a Yak3 at say 4000 or 5000m, accelerate to max speed (around 650km/h for both planes), then pick a dive angle - take for example 30 degrees in wonder woman view - dive to 2000m and measure the time. You'll see that nothing outdives the Jug from this speed up, not Yak3, not any other prop fighter.

JG14_Josf
03-17-2004, 10:34 PM
Buzzsaw,

I really don't want to step on anyones toes and, of course, you could be right, however, I don't think it is a function of real life physics to have it both ways.
What I mean is that if weight helps the plane accelerate going down then it can't help the plane going up.

Please consider this reference:

Fighter Combat

"The amount of energy gained or lost in the zoom depends on the average value of Ps during this period. To illustrate this concept, assume two fighters are identical in all respects, except one is heavier (maybe it is carrying more internal fuel). If they begin zooms at the same speed and altitude (i.e., same Es), Equation 4 shows that the lighter fighter will have greater Ps, will therefore add more energy during the zoom, and will ultimately zoom higher than the heavy fighter. Ps as well as energy state must, therefore, be taken into account when calculating the zoom capability, or "true energy height," of a fighter."

I think this is a very important point to understand. I could be wrong, but as the problem exists with heavy fighters in IL2/FB where their weight holds them back in climb but does not advance their progress going down, the opposite would be just as wrong where weight assists acceleration going down and going up.

Any zoom climb advantage a heavy plane has over a light plane must be the result of a mistake made by the pilot of the light plane.

Such as the case with the following example also found in Fighter Combat by Robert Shaw

page 184

"We flew together in formation, and then I decided to see just what this airplane had to its credit.
I opened the throttle full and the Thunderbolt forged ahead. A moment later exhaust smoke poured from the Spit as the pilot came after me. He couldn't make it: the big Jug had a definite speed advantage. I grinned happily; I'd heard so much about this airplane that I really wanted to show off the Thunderbolt to her pilot. The jug kept pulling away from the Spitfire; suddently I hauled back on the stick and lifted the nose. The thunderbolt zoomed upward, soaring into the cloud-flecked sky. I looked out and back; the Spit was straining to match me. and barely able to hold his position.
But my advantage was only the zoom-once in steady climb, he had me. I gaped as smoke poured from the exhaust and the Spitfire shot past me as if I were standing still. could that plane climb! He tore upward in a climb I couldn't match in the Jug. Now it was his turn; the broad elliptical wings rolled, swung around, and the Spit screamed in, hell-bent on chewing me up.
This was going to be fun. I knew he could turn inside the heavy Thunderbolt: if I attempted to hold a tight turn the Spitfire would slip right inside me. I knew, also, that he could easily outclimb my fighter. I stayed out of those sucker traps. First rule in this kind of a fight: don't fight the way your opponent fights best. No sharp turns: don't climb: keep him at your own level.
We were at 5,000 feet, the Spitfire skidding around hard and coming in on my tail. No use turning; he'd whip around inside me as if I were a truck loaded with cement, and snap out in firing position. Well, I had a few tricks, too. The P-47 was faster, and I threw the ship into a roll. Right here I had him. The Jug could out roll any plane in the air, bar none. With my speed, roll was my only advantage, and I made full use of the manner in which the Thunderbolt could whirl. I kicked the Jug into a wicked left roll, horizon spinning crazily, once, twice, into a thrid. As he turned to left to follow, I tramped down on the right rudder, banged the stick over to the right. Around and around we went, left, right, left, right. I could whip through better than two rolls before the Spitfire even completed his first. And this killed his ability to rurn inside me. I just refused to turn. Every time he tried to follow me in a roll, I flashed away to the opposite side, opening the gap between our two planes.
Then I played the trup. The spitfire was clawing wildly through the air, trying to follow me in a roll, when I dropped the nose. The Thunderbolt howled and ran for the earth. Barely had the Spitfire started to follow-and I was a long way ahead of him by now-when I jerked back on the stick and threw the Jug into a zoom climb. In a straight or turning climb, the british ship had the advantage. But coming out of a dive, there's not a British or German fighter that can come close to a Thunderbolt rushing upward in a zoom. Before the Spit pilot knew what had happened, I was high above himn, The Thunderbolt hammering around. And that was it-for in the next few moments the Spitfire flier was amazed to see a less maneuverable, slower-climbing Thunderbolt rushing straight at him, eight guns pointed ominously at his cockpit."

Please, before you conclude that a heavy fighter zooms better consider how Robert Shaw introduces this report:

Johnson, undoubtedly one of the greatest natural fighter pilots of all time, used his roll performance defensively to allow himself the chance to build an energy advantage in a diving extension.

Consider the possibility that the P-47 was able to zoom climb as a result of the higher relative energy state made possible by the Spitfire pilot's mistake to follow the P-47 in a dive.
Had the Spitfire pilot stayed level or climbed as the P-47 dove the energy margin would have favored the Spitfire.

Note Shaw's terminology:

page 179

"high-speed energy addition rate in a diving extension"

How can it be possible that a heavy fighter can lug the weight around to advantage?

The advantage is gained when the light fighter falls into the water, in the Sharks element.

Just as it is a mistake for the P-47 to climb against the Spitfire, it is a mistake for the Spitfire to dive against the P-47.

Going up the Spitfire gains energy relative to the P-47.

Going down the P-47 gains energy relative to the Spitfire.

But only if one follows the other.

If the Spitfire goes up while the P-47 goes down the Spitfire will increase total energy over the P-47.

Perhaps Robert Johnson is correct and in this case the P-47 is more capable of zooming, however it may not be as a result of increased weight, this does not figure, the advantage may be gained by aerodynamics.

Who knows?

JG14_Josf
03-17-2004, 10:52 PM
Magister_ludi wrote:

"We've been here a thousand times. A plane with better powerloading accelerates better in a dive up to max speed in level flight, then the heavier plane accelerates faster."

I sure would like to hear this type of discussion played out between Robert Shaw, Robert Johnson, Helmut Lipfert, Eric Brown, and those other British fighter pilots testing the capture 190-A3 in combat test trial and us.

My mind can be pried open to rewrite what those people wrote and correct their errors.

I think part of the problem may exists when a test pilot or aeronautical engineer is assuming that pilots fly around in combat at half throttle and they only choose to accelerate in a dive by adding more power.

Who knows?

I think that most combat situations are such that the planes are up against the wall where thrust equals drag and at this point gravity takes precedence as is the case with my motorized glider in ridge lift.

Please answer this question?
Will the motorized glider in ridge lift move forward or backwards in ridge lift as it drops ballast?

WWMaxGunz
03-18-2004, 12:04 AM
Johnson was able to start his dive much sooner as the Spit had to finish rolling into position to follow the faster rolling Jug.

Heavy plane will have a better zoom climb due to inertia of the extra mass but zoom climbs are not long lived. Lots of people have been posting about zoom climbs versus lighter planes but seem to think that zoom means until you're slowed clear down to or below sustained climb speed. Okay maybe techinically you still have zoom right down to sustained climb but the other guy is flying a different speed curve so if you milk it, you might just get caught up. Zoom from inertia has to comply with one of those laws of thermodynamics (been too damn long) that says you don't get out all of what you put in -- there's no such thing as a perpetual motion machine.

Energy? Ps, etc? Yes, there are equations showing initial zoom favors weight at speed. The heavier plane will lose more energy but then **it has more to lose**.

If Robert Shaw did not agree then he would have had more to say about the anecdote from Johnson.

Speed and alt can be traded noting that drag and thrust do enter into it. Put simply Alt = Speed * circumstances. You get to know how much speed you get from how much alt traded off depending on conditions (like initial speed and alt) and you get to know how much alt you can trade off excess speed for, knowing you can regain the speed or part of it (most if you fly well, more if you allow thrust to work into it) by dropping back down.

Speed or alt can be traded for angles. Speed for alt and vice-vera is like banking where speed or alt for angles is like buying something -- maybe a shot onto a target or a jink or other maneuver to save your butt, or maybe just a hard turn onto the approach to land because you want to blow speed.


Neal

Magister__Ludi
03-18-2004, 12:26 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by JG14_Josf:
Magister_ludi wrote:

"We've been here a thousand times. A plane with better powerloading accelerates better in a dive up to max speed in level flight, then the heavier plane accelerates faster."

I sure would like to hear this type of discussion played out between Robert Shaw, Robert Johnson, Helmut Lipfert, Eric Brown, and those other British fighter pilots testing the capture 190-A3 in combat test trial and us.

My mind can be pried open to rewrite what those people wrote and correct their errors.
<HR></BLOCKQUOTE>


Read this passage carefully, it is from a flight test comparison between 109F4 and 190A2:

"The comparison was flown at combat power, approximately 20% dive and a height difference of 2,000 m. The result was a lead of several hundred at all atltudes by the Fw 190 A-2. The steeper and longer the dive, the greater the lead. The tests did show, however, that the Fw 190 A-2 took longer to reach its maximum speed than the Bf 109 F-4"

You see that F4 outdives A2 up to max speed, even though A2 is much heavier and has a significantly more powerful engine than F4. Everybody states that 109 accelerates better initially, but usually they give no explanation of what this "initially" means. In the above passage however this is clearly explained, "initially" is replaced with: up to max speed in level flight (at the current altitude). Depending on the speed and altitude at which dive started it might not be "initially" at all, the lighter fighter (and with better powerloading) can put an advantage that cannot be nulified by the heavier plane.

Here's a chart with instantaneous acceleration at different speeds in a 30 deg dive at low altitudes (up to 1000m) for some important late war fighters:

http://mywebpages.comcast.net/bogdandone/30degdive.JPG

JG53Hunter
03-18-2004, 01:31 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Magister__Ludi:
[QUOTE]Originally posted by JG14_Josf:
Magister_ludi wrote:
...
Read this passage carefully, it is from a flight test comparison between 109F4 and 190A2:

"The comparison was flown at combat power, approximately 20% dive and a height difference of 2,000 m. The result was a lead of several hundred at all atltudes by the Fw 190 A-2. The steeper and longer the dive, the greater the lead. The tests did show, however, that the Fw 190 A-2 took longer to reach its maximum speed than the Bf 109 F-4"<HR></BLOCKQUOTE>

I hope i got that right but doesn't that passage say the 190A2 had the lead by several hundret in the dive BUT the 109F2 was faster than the 190A2 in accerlating to its max speed !? (i assume in level flight)

I may get that wrong thought English isn't my motherlanguage.

Greetings
Hunter

Magister__Ludi
03-18-2004, 02:27 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by JG53Hunter:

I hope i got that right but doesn't that passage say the 190A2 had the lead by several hundret in the dive BUT the 109F2 was faster than the 190A2 in accerlating to its max speed !? (i assume in level flight)
<HR></BLOCKQUOTE>


No, the whole passage is about dive, not level flight.
BUT max speed in level flight is very important for dive performance, as it is acceleration in level flight. Best dive acceleration will have the plane with the best acceleration in level flight (acceleration in level flight depends on power loading). This relationship is maintained up to max speed in level flight at the current altitude of dive, then the heavier plane will accelerate better up to compressibility speeds (the plane with a higher Mach number will be able to stay in a dive a little longer).

It's not very easy to explain, I'm not a native English speaker either.

JG53Hunter
03-18-2004, 06:21 AM
"The comparison was flown at combat power, approximately 20% dive and a height difference of 2,000 m. The result was a lead of several hundred at all atltudes by the Fw 190 A-2. The steeper and longer the dive, the greater the lead. The tests did show, however, that the Fw 190 A-2 took longer to reach its maximum speed than the Bf 109 F-4"


I think i have to get that text in its full context to understand it right. Do you have a link or a scan?

JG14_Josf
03-18-2004, 09:32 AM
Magister_Ludi,

I am not at all convinced one way or the other, however my most resent understanding makes the most sense to me.

It goes something like this:

Weight effects a planes ability to go up. An airplane's capcity to lift is reduced with the addition of weight. This is why the plane goes up in ridge lift when dumping ballast.

Picture the plane flying motionless above the ridge with all forces in balance.

The plane dumps the ballast and the balance of forces are no longer equal. No longer can the airplane hold it's possition motionless against the forces present on earth.

The only thing that changes on the plane is a loss of weight.

So it is easy to see now that weight lessens the planes capacity to lift because the plane will climb higher on the ridge as it dumps ballast. The plane changes only it's weight and in so doing the plane gains lift.

Where all other forces were equal now the force of lift is greater as a result of the reduced weight.

All done?
Everything is abundantly clear? Light planes lift better than heavy planes?
Light planes climb better than heavy planes?

Reasonable?

Now place that same plane on the ridge flying motionless with all forces in balance and fill it's empty ballast tank. (use your imagination or a flexible rubber tube)

What happens?

It seems reasonable to conclude that the plane goes down, since the plane dumping balast went up; naturally and logically the plane gaining balast will go down.

Fill the plane and empty the plane and watch the plane go down and then up on the ridge.

Up the plane goes as ballast is removed and down the plange goes as ballast is added.

The only force that changes in this scenario is lift or is it?

Add weight, add a little bit of weight and the plane decends a little bit. Add a lot of weight and the plane decends a lot. Remove a little bit of weight and the plane climbs up a little bit, remove a lot of weight and the plane climbs up a lot, right?

So, can we use the word acceleration for this effect?

Remove a little bit of weight and the plane accelerates up a little bit.

How about that, is that right?

Now add a lot of weight.

Does the plane accelerate down a lot?

One more thing on this scenario and I know this to be true. I've flown in ridge lift and with my limited imagination I can still feel this experience.

It is one of my favorite memories.

Our plane in ridge lift does not simply go up and down with the addition and subtraction of weight.

It moves back and forward too.

Up and back as weight is removed.

Foward and down as weight is added.

The removal of weight cause an acceleration up and a deceleration foward.

The addition of weight causes a deceleration up and an acceleration forward.

Words are sometimes inadequate when a person is trying to communicate an understanding, perhaps that is why people invented math.

The addition of weight decelerates upward and backward motion.

The subtraction of weight decelerates downward and forward motion.

How about this:

Lift causes drag and drag resists forward movement through the air.

Removing lift and the associated drag resulting from lift will allow a plane to accelerate in the atmosphere.

Weight removes lift.

Regardless of what I think, there are reports that conclude:

Wings of the Luftwaffe by
Capt. Eric Brown

"The Fw 190 had tremendous initial acceleration in a dive..."

Magister__Ludi
03-18-2004, 09:57 AM
Josf,

You cannot use gliders as a good model to understand dive performance. Gliders do not generate own thrust, they rely on air streams, otherwise they simply go down at a constant sink rate, regardless of weight, if optimal AoA is maintained (optimal AoA for best sink rate is the same regardless of weight, only forward speed (TAS) vary).

You have to take into consideration the fact that planes use their own power in a dive. The thrust generated by the plane is larger than drag up to max speed (in level flight, at current dive altitude), then only weight counters the excess drag (in excess over thrust) - this is the moment in which heavier plane dives faster.

Look in this picture and check the slope of the acceleration graphs for each of the planes. The slopes are steeper for planes with better powerloading, but after max speed in level flight (which is around 350mph at low level for the planes in the chart) the heavier planes accelerate better.

http://mywebpages.comcast.net/bogdandone/30degdive.JPG

Magister__Ludi
03-18-2004, 10:03 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by JG53Hunter:
I think i have to get that text in its full context to understand it right. Do you have a link or a scan?<HR></BLOCKQUOTE>


This is an excerpt from a Rechlin comparison test between 190A2 and 109F4, made prior service. Point C of the evaluation is about dive performance:


"C: Dive
The comparison was flown at combat power, approximately 20% dive and a height difference of 2,000 m. The result was a lead of several hundred at all atltudes by the Fw 190 A-2. The steeper and longer the dive, the greater the lead. The tests did show, however, that the Fw 190 A-2 took longer to reach its maximum speed than the Bf 109 F-4."

JG14_Josf
03-18-2004, 11:12 AM
Magister_Ludi,

You can determine how you think and what evidence you use to try and understand how the world works, but you cannot tell me how I think and what evidence I use to try and understand how the world works from my perspective.

If you do not have a problem with understanding the effect of weight on aircraft performance and if you find no reason to question the disparity of information that seems to contradict this relationship then by all means find comfort in your enlightenment.

Your chart looks like something derived from a flight sim game.

The ridge lift example can include a plane with an engine and if the plane is held on the ridge with enough ridge lift to offset the engine power then it stands to reason that the powered plane is at max speed.

What happens to the plane as it dumps ballast?

My example does not purport to show how a real P-47 or real Fw 190 accelerated against a real Spitfire. Real pilots flew those planes and they reported relative dive acceleration. I do not profess to contradict or confirm their findings.

My example appears to confirm my understanding that weight adds to forward thrust and if this is true then it seems logical to me that this is always true and is not made untrue just because a plane also has an engine and is not made untrue just because a plane is not a max speed.

My ridge lift example appears to show that the addition of weight accelerates the plane foward and down, and the subtraction of weight accelerates the plane backwards and up.

It also shows to me that as the factor of weight increases so does the factor of acceleration, where a lot of weight makes for a lot of acceleration and a little weight does not accelerate much.

WWMaxGunz
03-18-2004, 11:32 AM
Gaining alt loses speed, losing alt gains speed.
It trades one for the other at some exchange rate.
That's what happens easiest explained.

Losing weight means less downward force against the wind, so the wind pushes it back.
That is also true.

They all blend together at once. Nature is beautiful.


Neal

faustnik
03-18-2004, 12:00 PM
What is "retained energy"? I thought heavy planes used this to advantage in a zoom climb?

Talk slow please, my degree is in Anthropology not physics.

http://pages.sbcglobal.net/mdegnan/_images/FaustSig
www.7Jg77.com (http://www.7jg77.com)
CWoS FB forum. More Cheese, Less Whine. (http://www.acompletewasteofspace.com/forum/viewforum.php?f=25)

WWMaxGunz
03-18-2004, 12:23 PM
"The comparison was flown at combat power, approximately 20% dive and a height difference of 2,000 m. The result was a lead of several hundred at all atltudes by the Fw 190 A-2. The steeper and longer the dive, the greater the lead. The tests did show, however, that the Fw 190 A-2 took longer to reach its maximum speed than the Bf 109 F-4"

My English is pretty good. It says maximun speed but not what maximum speed. Since the subject is dives though the safest bet is that they speak of maximun speed in the dive, whichever dive at whatever alt since they did many, no? 20% dive at combat power, those planes really moved, hey?

If that is correct then the FW (in the tests) took longer to go faster. How much faster? Result of several hundred meters seperation in a travel length of ....

Lets see if I get this right, anyone who knows better please correct:

20% dive is 20% rise (vertical distance) to run (horizontal distance). 2km vertical to 10km horizontal, travel distance = sqrt(4 + 100)km is still just a hair over 10.2km.

.... 10km is close enough when the other value is "several hundred". Is several hundred less than 1km? They are talking meters, yes? If so than less than 10% but far enough to be beyond effective fire by the end of the test run.

Very important to specify that seperation is at the end of the run. If it was soon and the FW was moving faster than the 109 then the seperation would be much longer, right?

So the FW gets less than a 10% lead in the dives regardless of starting alt (it says at all alts) but with combat speed to start. The FW ends up going faster as well. If the dive continues then the FW will be pulling away at a greater **average** rate in the longer dive than in the test dive but at the same rate as when both planes did reach the maximum velocity for their 20% dives at whatever alt the particular test was made.

Before they both reached their maximum 20% dive speeds the relationship was different. Just how different it does not say. I have a feeling that the 109 never passed ahead of the FW but I have no evidence of that, just that I'd think if the writers were fair then such would be noted. I cannot assume fairness or completeness however all the way from the tests to what the author put into the book.

It does say that the 109 reached its maximum speed (for reasons above I believe that is the 20% dive speed) sooner than the FW reached its maximum. And that with the rest tells me some things.

1* Both planes reached maximum before the end of the dives.
2* The FW maximum was always higher speed.
3* The FW got further ahead by the end of the dive than it was when it reached maximum speed.
4* When the 109 reached maximum dive speed the seperation to distance travelled was proportionately less than the ratio of speration to travel at the end of the dive. That was also before the FW reached maximum speed.

The seperation at the end was less than 10% of the total distance travelled, I am guessing since exactly how many hundreds of meters is not stated.

Without knowing the maximum dive speeds and times each took to reach them there is no real guessing how close they were at any points along the way. And those numbers vary with the start alt in every case as does the final seperation.

Only conclusion I can come to besides is that the FW had to travel 10km to gain a lead of several hundred meters and that at that point the relative speeds were not changing by much though still changing as alts got lower, more drag but different supercharger/engine power states might make the dynamics interesting and/or misleading.

5* The lead was less that half as much in the middle of the dive as it was at the end since by the end the average speed difference for the entire dive was at the greatest. This very probably holds true for at any fraction of the dive.

All this depends on the maximum speeds noted being maximum for the 20% dives. Well, it mostly or I think still totally holds true if the maximum is maximum level speeds as well since either way it is about relative speeds only and the FW has the higher maximum according to the original quote.


Neal

Edit: PS -- wow a lot of meaning can be packed into 4 sentences, hey?

Magister__Ludi
03-18-2004, 12:51 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by JG14_Josf:
Magister_Ludi,

Your chart looks like something derived from a flight sim game.<HR></BLOCKQUOTE>

I made the chart when I was trying to verify the dive and zoom climb of the planes in FB. It matches perfectly what I found in FB, though I have no inside information about how dive/zoom climb performance is calculated in FB.

The only weakness is that it does not take into account compressibility (FB does't either) but the compressibility effects are small since this chart is valid at low alts (below 1000m) where 500mph is around 0.65 Mach (compressibility effects start to become significant just above this speed for late war fighters).


<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>
My ridge lift example appears to show that the addition of weight accelerates the plane foward and down, and the subtraction of weight accelerates the plane backwards and up.

It also shows to me that as the factor of weight increases so does the factor of acceleration, where a lot of weight makes for a lot of acceleration and a little weight does not accelerate much.<HR></BLOCKQUOTE>

As long as you are talking about a glider not in ridge lift, then the above is correct. Ridge lift is an unnecessary complication for this problem.


<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>
My example appears to confirm my understanding that weight adds to forward thrust and if this is true then it seems logical to me that this is always true and is not made untrue just because a plane also has an engine and is not made untrue just because a plane is not a max speed.<HR></BLOCKQUOTE>

This is incorrect. Though a complete physical explanation would be more apropriate, I'll do a simple one first:

* You forget that you are comparing different planes, not the same plane at different weights. This is very important because heavier planes are larger and produce more drag. For example P-47D-25 has a slightly smaller max speed at sea level than Yak-3, though uses twice more HP to achieve this speed. This means that P-47 produces twice the drag of an Yak-3, so even though P-47 has more than twice the weight of Yak-3 it also has to counter twice the drag of a Yak-3.

* Not all the weight has a contribution to dive acceleration, only sin(dive_angle) multiplied with weight adds to thrust to counter drag, at 30 degrees only half of the weight adds into the equation. Drag on the other hand adds to the last lb, regardless of dive angle.

* Thrust is very powerful, for example at 100mph Dora produces in excess of 4000lb thrust.

In conclusion a P-47 will dive faster than an Yak-3 if the planes have their engines off (windmilling props will complicate the problem, but we'll ignore this now) regardless of speed; if both planes have their engines at combat power, then Yak-3 will accelerate faster in dive up to max speed in level flight, when P-47 will accelerate faster.

[This message was edited by Magister__Ludi on Thu March 18 2004 at 12:13 PM.]

Magister__Ludi
03-18-2004, 01:08 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by WWMaxGunz:
"The comparison was flown at combat power, approximately 20% dive and a height difference of 2,000 m. The result was a lead of several hundred at all atltudes by the Fw 190 A-2. The steeper and longer the dive, the greater the lead. The tests did show, however, that the Fw 190 A-2 took longer to reach its maximum speed than the Bf 109 F-4"

My English is pretty good. It says maximun speed but not what maximum speed. Since the subject is dives though the safest bet is that they speak of maximun speed in the dive, whichever dive at whatever alt since they did many, no? 20% dive at combat power, those planes really moved, hey?

...

All this depends on the maximum speeds noted being maximum for the 20% dives. Well, it mostly or I think still totally holds true if the maximum is maximum level speeds as well since either way it is about relative speeds only and the FW has the higher maximum according to the original quote.

<HR></BLOCKQUOTE>


Both planes have the same speed limit in a dive, which at low altitudes is 750kmh TAS. That would mean that F4 accelerated faster to 750km/h in dive than A2. This literal interpretation of the text is much more radical than what I said, I was thinking that F4 was better than A2 up to 550kmh TAS (low alts). Neal's interpretation is of course incorrect: this was not a test for the behaviour of those aircrafts outside their specified flight envelope (over 750km/h TAS), also
there was no way they would try to dive to max speed so close to the ground (dive speed limit would have been reached very close to the ground if dive begins at 2000m - I assume both planes start the dive from cruise speed).

The test gives a better mark to A2 from dive characteristics point of view, which would be meaningless if A2 would have an advantage only outside the envelope (at speeds higher than maximum allowed dive speed).

PzKpfw
03-18-2004, 01:29 PM
Dean provides an dive capability comparison anlayss* in AHT which deals with dive speed from 25000ft to 10000ft @ 30 & 90‚? angle below is the ranking of US fighters Ie:

1 - P-38G
2 - P-51D, F4U-1D (tie)
3 - P-47D
4 - F6F-5
5 - P-39D
6 - F4F-4
7 - P-40E

@ 10,000 feet when the 1G limit had been reached:

P-47D - 500mph IAS
P-51D - 500mph IAS
P-63A - 500mph IAS
P-40E - 480mph IAS
P-39Q - 475mph IAS
F6F-5 - 449mph IAS
F4U-1D - 443mph IAS
P-38J/L - 440mph IAS
P-61A - 430mph IAS
FM-2 - 425MPH IAS

In later tests both the P-47D-20 & P-51B-5, out dived the P-38J.

In postwar tests the dive order for US fighters was:

1 - P-47D-40
2 - P-51D
3 - F6F-5
4 - FG-1D (F4U-1D)

*See: Dean Francis H. America's Hundred-Thousand p. 605

Some more dive comparison testing from RAF conducted flight tests, @ Duxford to evaluate the P-51B.

Dive:

- P-51B superior to Spitfire IX.

- Tempest V equal to & superior to P-51B in extended dives.

- FW 190A-4 initial advantage, P-51B overtakes in extended dive.

- BF 109G-2 initaial advantage P-51B overtakes in extended dive.


Regards, John Waters

[This message was edited by PzKpfw on Thu March 18 2004 at 01:47 PM.]

WWMaxGunz
03-18-2004, 02:22 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Magister__Ludi:
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by WWMaxGunz:
"The comparison was flown at combat power, approximately 20% dive and a height difference of 2,000 m. The result was a lead of several hundred at all atltudes by the Fw 190 A-2. The steeper and longer the dive, the greater the lead. The tests did show, however, that the Fw 190 A-2 took longer to reach its maximum speed than the Bf 109 F-4"

My English is pretty good. It says maximun speed but not what maximum speed. Since the subject is dives though the safest bet is that they speak of maximun speed in the dive, whichever dive at whatever alt since they did many, no? 20% dive at combat power, those planes really moved, hey?

...

All this depends on the maximum speeds noted being maximum for the 20% dives. Well, it mostly or I think still totally holds true if the maximum is maximum level speeds as well since either way it is about relative speeds only and the FW has the higher maximum according to the original quote.

<HR></BLOCKQUOTE>


Both planes have the same speed limit in a dive, which at low altitudes is 750kmh TAS. That would mean that F4 accelerated faster to 750km/h in dive than A2. This literal interpretation of the text is much more radical than what I said, I was thinking that F4 was better than A2 up to 550kmh TAS (low alts). Neal's interpretation is of course incorrect: this was not a test for the behaviour of those aircrafts outside their specified flight envelope (over 750km/h TAS), also
there was no way they would try to dive to max speed so close to the ground (dive speed limit would have been reached very close to the ground if dive begins at 2000m - I assume both planes start the dive from cruise speed).

The test gives a better mark to A2 from dive characteristics point of view, which would be meaningless if A2 would have an advantage only outside the envelope (at speeds higher than maximum allowed dive speed).<HR></BLOCKQUOTE>

Okay. If both have the same max dive speed of 750kph and the 109 reaches that speed quicker than the FW... how is it the FW has the lead at the end of the dive at all let alone by several hundred meters? That makes no sense.

Could it be possible that in real life the FW 190 A2 tested had a higher dive maximum than the 109 F4 tested? Could it be possible that in real life there are limits or capabilities that an imperfect simulation cannot model all of?

The dives don't begin at 2000m. The dives all had a height difference of 2000m. That is from start of dive to end of dive.

If these statements are true:

"The result was a lead of several hundred at all altitudes by the FW 190 A2."
"The steeper and longer the dive, the greater the lead"

Does that mean that all during the dives the FW had such a lead from the top to bottom "all altitudes"? Or does it mean that the 2000m dives were conducted at different starting altitudes and at the ends of every test the FW had a lead of hundreds of meters?

These are the kinds of problems I see with interpretations of accounts. It is best to draw pictures and weight the logic of statements and how they mean to the reader to test for complete consistency. If no way consistency can be shown then either the reader/interpreter is not right or the writer has not given enough information or incorrect information.

I really don't think I had it that wrong.

Only if the FW had a faster speed could it end up with a lead given that the 109 reached maximum speed quicker. In a dive, both go faster than on level but is there some magic where the 109 reaches maximum level speed quicker and then suddenly waits for the FW to pass it up? Weight and thrust work together, not step 1 then step 2. Not so simple.

Weight force plus thrust force overcome drag force until through speed increase drag becomes equal to the others combined. In level flight it is only thrust force alone against drag. The level maximum speed is the outcome of thrust alone versus drag, not an intrinsic speed at which the prop cannot go faster. Witness to this is that maximum level speed at different altitudes is different as power and drag both vary.

In a dive, weight force is added to thrust. For dive acceleration the acceleration of mass in gravity can only be so much, sine of dive angle from horizontal x gravity acceleration, so that with =enough= thrust acceleration you can pull down faster until that is overcome. But just because in a dive the speed reaches level maximum for the alt doesn't mean the prop has necessarily reached zero net thrust. You take torque off the engine by taking force off the engine through use of weight force helping and that engine will be able to go faster, no?

It is all one really, the splitting of forces into vectors makes the math workable but the math works only as a whole.


Neal

WWMaxGunz
03-18-2004, 02:26 PM
John, was there anything to show that a 90 degree dive reached max G limit before a 30 degree dive, as I'm kind of thinking it should?

15,000 ft is kind of a long dive just for that. What else were they finding out?


Neal

PzKpfw
03-18-2004, 02:53 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR> Originally posted by WWMaxGunz:
John, was there anything to show that a 90 degree dive reached max G limit before a 30 degree dive, as I'm kind of thinking it should?

15,000 ft is kind of a long dive just for that. What else were they finding out?


Neal<HR></BLOCKQUOTE>

Hi Neal not sure ATM, am reading thru AHT's dive sections.

Dean is not clear on the 10000ft section Ie, I cant tell if the order listed is 'ranking' Ie, the P-47D reached 500mph IAS first or if he is just listing speed reached before pullout etc.

Maybe Chimp can toss in his take on that section.

Regards, John Waters

---------
Notice: Spelling mistakes left in for people who need to correct others to make their life fulfilled.

------
"We've got the finest tanks in the world. We just love to see the German Royal Tiger come up on the field".

Lt.Gen. George S. Patton, Jr. Febuary 1945.

JG14_Josf
03-18-2004, 03:25 PM
Magister_Ludi,

If you think this statement:

"My example appears to confirm my understanding that weight adds to forward thrust..."

means this:

"you are comparing different planes, not the same plane at different weights."

Then we are not communicating.

Is or is it not true that a powered Plane in ridge lift flying in such a manner as to be stationary relative to the ground will accelerate upwards and backwards relative to the ground if the plane drops ballast?

I would like to learn the facts concerning relative dive speeds between WWII combat fighter planes but you must understand a few things about me if your intentions are to convey knowledge.

1. I am not too smart.

2. I place value in the opinions of the people who actually flew these planes in combat and therefore the information they report on this subject carries value in my judgment.

It occurs to me that you may think you know how these planes did compare in dive performance and it occurs to me that you may be right, but it is not going to be possible for you to convince me of this fact even if it is a fact if you continue to disregard what I write and if you continue to assume meaning in my words that is not intended by me.

Functio
03-18-2004, 04:04 PM
Just to make sidetrack from the above discussion -

The Spitfire doesn't seem to suffer very much at all fom the effects of compression. Now, is this an actual trait of the Spitfire, or does it point to an error of some sort?

JG14_Josf
03-18-2004, 05:59 PM
Faustnik wrote:

"What is 'retained energy"? I thought heavy planes used this to advantage in a zoom climb?"

Since the subject also interests me and since I am also working on the answer to this question, and since I like to write; I'm going to examine this question and at some point in time when the picture appears to be clearer I'll return to this, or the latest, discussion on this topic.

Fixed Wing Performance (http://flighttest.navair.navy.mil/unrestricted/FTM108/)

SkyChimp
03-18-2004, 06:46 PM
John, those are just the placard dive speed limitations at 10,000 feet.

Regards,
SkyChimp
http://members.cox.net/us.fighters/skychimp.jpg

WWMaxGunz
03-18-2004, 06:51 PM
Retained energy might be momentum.
That's velocity x mass.

Moving things are harder to stop in direct proportion to their weight.

Same plane with more weight and same speed will be able to get that initial climb higher trading inertia for altitude. After the zoom if it continues to climb that will be at the sustained rate for its weight, power and alt plus any etcs that don't count as much.
The same plane with less weight will benefit more from thrust during the total climb, both zoom and sustained. It won't have the inertia benefit for the beginning of the zoom and however far the excess weight of the other carries it but it will have a higher sustained climb and Ps so it will be playing catch-up the whole way and I believe should be climbing faster before the heavier one has reached its own lower sustained climb speed that the lighter one won't drop to at all.

I could say swing a pendulum. They don't have thrust though so I don't want to confuse things. Still the trade between alt and speed can be seen at least without the element of thrust and the changes it makes. You can also use different weight pendulums released from the same height and stop them with your hand at the bottom of the swing. The best part of physics is always the experimenting. It's playing with nature and reality!

An Anthro major? Most I've done is an intro to Cultural Anthro (very interesting) and for 10 years or so read loads of anthro articles in Sci American mag. I guess you're intrigued or exceited about those teeth they just released the news about? Or is that paleo?


Neal

boohaa
03-18-2004, 06:56 PM
I just did zoom climb tests and was pleasantly suprised with results.I say suprised because it seems to be a new feature in AEP http://ubbxforums.ubi.com/images/smiley/11.gif

In FB 1.0 all planes zoomed to exact same alt.

OK here is how I did it and my results.Dove down and pulled up at 600KPH/radiator closed and ENGINE OFF to remove all thrust from equation.So in this sense it is pure drag/weight.

P47-D27.....950M
FW190-A9....800M
LA7.........450M
Yak3........600M

This is 3 attempts for each plane.I am alittle stumped by the YAk3 here though.How does a plane that weighs so little keep so much energy in a zoom climb.Is the drag for it that low???

PzKpfw
03-18-2004, 07:17 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by SkyChimp:
John, those are just the placard dive speed limitations at 10,000 feet.

_Regards,_
_SkyChimp_
<HR></BLOCKQUOTE>

Ah ok Chimp Dean does not make that clear from the text that those were placard limits.

Regards, John Waters

---------
Notice: Spelling mistakes left in for people who need to correct others to make their life fulfilled.

------
"We've got the finest tanks in the world. We just love to see the German Royal Tiger come up on the field".

Lt.Gen. George S. Patton, Jr. Febuary 1945.

WWMaxGunz
03-18-2004, 07:21 PM
Low drag and the wings are better for making the transition from down to up with less speed loss.

If you save tracks then you can run them through playback and use pause to grab the speed data then catch the timing on another playback to make your own data charts. If you run no cockpit then you get even more data.

Also try not shutting the engine off but dropping power to 20% and pitch to the same with CSP planes to avoid having prop and engine drag affect your results. Oh, and get the data you may find about how much drag in some fashion.


Neal

Aaron_GT
03-18-2004, 11:00 PM
Neal: mv isn'r an energy - 0.5mv^2 is, though.

Aaron_GT
03-18-2004, 11:16 PM
Josf wrore:
"A heavy plane will dive faster than a light plane.

A heavy plane will bleed energy faster than a light plane."

No...

The mass doesn't make any
direct difference (if we
assume a frictionless
environment )

potential energy=mgh
kinetic energy=0.5mv^2

m cancels out

in an environment with
friction, and no thrust
then for zoom (to
0 speed) we have

mgh=0.5mv^2 - X or
h = 0.5v^2/g - X/mg

where X is the energy lost
to drag.

Planes that are large have
more drag, and more mass,
but the tend to have less
drag per unit mass than
smaller planes. Thus larger
planes should tend to zoom
better with engines turned
off.

With the engines running
too then power loading
comes back into the ewuation
and with two otherwise
equal planes the one with
the better powerloading will
win.

For a yak versus a p47 then
the relative power loading
AND drag are important, and
the relative balance.

So there is nothing in AEP
that sounds to be obviously
wrong.

Ditto a heavy plane only
tends to win in a dive
eventually because drag
per unit mass tend to be
lower. (this is only a general trend of course -
specific examples may differ!)

WWMaxGunz
03-19-2004, 01:16 AM
Mass x Velocity is Momentum. Check ballistics tables, they often list both or just MV. Also known as knock-down force and a very real measure of projectile power. Yeah KE is the energy but MV is... I forget my terms so you put a label on Momentum for me?

KE penetrates, MV knocks down or carries. I've had that one explained in words and examples since I was 12. It's just as real, only the mechanics differ. Catch a baseball moving twice as fast and it smacks the skin of your hand 4x as hard but is only 2x as much to your arm. There's a nice transferrence method for KE but the quick and easy is MV. I can do math either way for simple results and simple is all at least I'm trying to keep it to here.


Neal

Aaron_GT
03-19-2004, 01:34 AM
Neal, the original reference was to 'retained energy'. I was just pointing out that momentum isn't energy (wrong dimensions).

Aaron_GT
03-19-2004, 01:37 AM
"Also known as knock-down force and a very real measure of projectile power. Yeah KE is the energy but MV is... I forget my terms so you put a label on Momentum for me? "

The normal label for moment is p, p=mv.

The force derived from momentum is termed
impulse, which is dp/dt (to strictly momentum
is not a knock down force, only the change of
momentum).

Strictly Newton actually stated F=dp/dt, which
works at special relativistic speeds too. For
Newtonian physics m is not m(v), so it comes
down to F=m.dv/dt, or ma.

Ugly_Kid
03-19-2004, 05:32 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by RAF74BuzzsawXO:
Because the physics model of the game does not seem to take into account the effect of greater mass, both in dive acceleration, and in zoom climb, we have a situation whereby aircraft such as the 190A or P-47D lose a significant advantage which they enjoyed in real life.
<HR></BLOCKQUOTE>

That's rather broad statement, how would you know this? The fact is you don't and besides before you lay down some analysis of what to expect and why it's something else in the game you can't really just write something like that.

As a simpliest help to get the very first estimate of what to expect you just have to open the IL2Compare. There is unfortunately only a chart of climb rate vs. velocity for the SL. However, you will see that a fast aircraft like FW and P-47 will eventually outclimb most of the slower opponents at some higher speed. You can say that from this point on they will also outaccelerate their opponents in a) horizontal flight or b) in a dive. If you turn circles with 270 km/h against yak in that jug and realize "heck I can't turn with him" there is no secret get-hell-out-of-dodge trick. On your way to 500+ km/h in a dive you will be eaten alive twenty two times to hell and back yak even has to cut back that throttle. If you repeat the same stunt at an engagement with 450 km/h your changes are better. There is hardly another aircraft that will dive like FW or P-47 from 500 km/h on. Most of the simmers are just way too slow and have quite overmodeled expectations.

What Neal wrote about mass being a hindrance before level flight top speed and being an aid after it, is correct. In a 700 km/h dive the plane with smaller top speed actually bleeds more E compared to another plane with higher level flight top speed, also worth knowing. Put Bf-109 in a small dive and hold some 500+ km/h and the following I-16 if started from co-E or even if he had E-advantage will bleed to a disadvantage during a prolonged dive. Prolonged dive is not a typical DF-gamers 500 m spurt with jug from 1000 m and then "sniff sniff sniff FM is crap".

As for that "fact" about mass being not correctly accounted for, the gentlemen should have a little bit more knowledge about a typical simulator code. Simulation FM works with time integration proceeding forward, not by reversally solving a system.

Now typically you calculate E=0.5*m*v^2 kinetic energy. You solve the system by saying with force F I will travel distance s by dividing E/F. So you have solved the system.

FM works differently it would account for forces and make a resultance F. Now with this F it would divide it with the weight to come to an acceleration a, so with this we look at the speed change and stepwise integrate forwards.

For example initial velocity v
steps:

time velocity distance
0 v0 s0
t/10 v1=v0-F/m*(t/10) s1=s0+(v0+v1)/2*t/10
2*t/10 v2=v1-F/m*(t/10) s2=s1+(v1+v2)/2*t/10
3*t/10 v3=v2-F/m*(t/10) s3=s2+(v2+v3)/2*t/10
...
10*t/10 v10=v9-F/m*(t/10) s10=s9+(v9+v10)/2*t/10

If you try this with practical numbers you will realize that the iteration process does not contain that mystical parameter
kinetic energy E nor a function called energy retention. However, the system works and in the end you will get the same result. So how an earth could you leave something like an effect of the mass out of the system? http://ubbxforums.ubi.com/images/smiley/52.gif You will develop only moments and forces based on airspeed, thrust and angle of stream.

Another partly different issue is E-bleed in the turns, this issue is related to generating the forces in a certain conditions (flight with high angle of attack). Now if you don't penalize this state with correct force balance you will get wrong E-bleed in tight turns issue. However, the integration is still correct itself. You can speculate about lift being not correct, you can speculate about thrust and drag but it is pretty unlikely that there is a secret conspiracy that gives aircraft different gravity vectors...

JG14_Josf
03-19-2004, 08:38 AM
Aaron_GT wrote:

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Josf wrore:
"A heavy plane will dive faster than a light plane.

A heavy plane will bleed energy faster than a light plane."

No... <HR></BLOCKQUOTE>


The above appears to declare that my statement is wrong, yet when comparing the context of my quotes to the context of the words following the word "No..." is appears to me that it is a simple matter of coincience.

Aaron_GT,

Why did you us my quote to begin one of your declarations of physical facts, and why did you add the word "No" after your quote of my words?

I cannot see any relation between the context of my post where you extracted that quote and the context of your post that includes my quoted words, please explain the correlation between your post and my post if there is one.

My post, where those words were found, had to do with energy maneuverability. Your post seems to report some conclusions based upon large planes vs small planes and something about a frictionless environment, and the Yak and P47 relative power loading.

Why did you stick my quote at the begining of your quote and why follow my quote with the word "No"?

Are you meaning to refute my new found understanding that Altitude is energy and that the loss of altitude can be seen as a loss of energy even though it is an increase in velocity? That perhaps the heavy plane relative to the light plane is dumping energy as a sum total of energy yet for practical applications in combat the heavy plane is extending relative possition even though the net energy state is a loss.

If you are refuting that understanding then I have not found any evidence in your words to support this fact.

Communication is not easy. It takes at least the desire to accomplish the task from at least two people.

Aaron_GT
03-19-2004, 09:47 AM
"Why did you us my quote to begin one of your declarations of physical facts, and why did you add the word "No" after your quote of my words?"

Because I thought your statement was a bit
misleading. On reflection it was actually
correct (and I apologise), although see below:

You are correct that a heavy plane will
bleed energy faster. However, it will bleed
it more slowly as a proportion of its
initial energy (which was the point I was
trying to make). In terms of things like
zoom climb (which was being discussed) the
rate of loss of energy as a proportion of
the original energy is the important factor,
in determining how well a plane zooms,
not the total amount of energy lost, or
the gross rate of loss.

"Are you meaning to refute my new found understanding that Altitude is energy and that the loss of altitude can be seen as a loss of energy even though it is an increase in velocity? "

No - that would be a totally correct
statement of how the physics works.

Basically I was trying to show that a massive
plane will have a maneouvering advantage
as it will retain a greater proportion of
its energy as it tends to have less drag
per unit mass.

Sorry if my pervious post seemed a little
bit offhanded. I was trying to get the point
across that heavier planes tend to dive and
zoom better assuming that they have the
same power loading, due to the typically
lower drag per unit mass of objects scaled
up.

JG14_Josf
03-19-2004, 12:08 PM
Aaron_GT,

Thanks for the kind reply.

I've managed to find time to work on this more and have arrived at a new point of perspective. This time I am reluctant to label this condition as a state of understanding.

It seems more answers simply lead to more questions.

Es(ft)= H + Vsquared/2g

Ex = Specific Energy
H = Altitude
V = Velocity
g = Gravity

Specific Energy or Es or E sub s is an accounting of three variables; altitude, gravity and speed.

Any 2 objects can be compared with this mathematical accounting.

An object 20000 ft above the earth at 0 speed has the same Specific Energy state as another object at sea level that is traveling at approximately 700 knots.

The purpose of Specific Energy is to have a point of reverence, a standard by which to compare two objects and in this case we are concerned with Airplanes.

Specific Energy is very limited in scope, it does not take into account anything more than three factors those being Speed, Altitude, and the force of gravity, therefore the two airplanes being compared by this method will also be very limited in scope.

Plane A at 20000 feet at 0 velocity is at the same level of energy against the force of gravity as is plane B at sea level going 700 knots.

It is true with this standard of comparison known as Specific Energy that Plane A can drop down to plane B just as quick as Plane B can zoom up to Plane A but only if the atmosphere is removed from the planet earth and only if Plane A is directly above plane B and only if Plane B is vectored at Plane A.

Specifc Energy can be computed and charted on graph paper.

Specific Energy allows someone the advantage of knowing how altitude and speed are relative, and for fighter pilots this is valuable stuff.

Going faster is just as good as being higher and visa versa.

It should be clear that Plane A has no advantage over Plane B despite the fact that Plane A is 20000 feet higher than plane B.

I should be just as clear that Plane B has no advantage over Plane A despite the fact that Plane B is going very fast while Plane A is not even moving.

Ps(ft/sec) = [T-D/w]V

Ps=Specific Excess power
T = Thrust
D = Drag
V = Velocity

Specific excess power or Ps or P sub s is an accounting of three more variable that add to the fighter pilots ability to compare two planes.

These three extra variables take into account enough information to place our two planes that have already been described with the earlier simpler accounting and add into the comparison an atmosphere and an engine.

The bottom line is that Plane A and Plane B will meet somewhere and this exact spot isn't important but both pilots would like to know who has the shorter or longer end of the stick when that point is reached. This is where time is important. It takes time for things to happen. In other words things happen in time.

In this case we are finding out how many feet will be traveled in a given amount of time.

P sub s is measured in feet per second.

Specific excess power is a measurment of how many feet a plane will travel in one second.

Going back to the earth without the atmosphere where plane A and Plane B have a specific altitude and a specific speed and a specific state of energy we can now apply another number to find out more information on how these two planes compare.

Remember Plane A at 20000 feet pointing down at Plane B, and Plane B going 700 Knots pointing up at Plane A?

Es or E sub s or Specific Energy is the same in both of those planes.

When Plane A falls it will meet Plane B half way down and Plane B will take just as much time to burn up all that speed to reach that half way point.

That is what would happen if no atmosphere existed and no engine thrust existed.

Specific Energy does have limitations.

P sub s or Specific excess power should give us a more accurate accounting of the physical relationship of these two planes, but we still need to compare Specific excess power to Specific Energy, in other words we still need all the information found in Specific Energy, we need to know the force of gravity and the altitude of the planes being compared.

Speed is also a part of the Ps Specific excess power equation.

Ps or P sub s will let us know how many feet per second Plane A will gain relative to Plane B and Specific Excess Power or Ps gives us how many feet per second Plane B will shed on it's way up toward Plane A.

Every single required piece of information is available in the Ps equation for us to determine where these two planes will meet; we have in the Specific Excess Power equation an accounting of Thrust, Drag, Weight, and velocity.

No

What about lift?

JG14_Josf
03-20-2004, 08:44 AM
Lift is not entered into that equation unless the factor of total drag includes the drag force generated by lift and not unless the factor of total thrust includes the thrust generated by lift.


Back to the earth without the atmosphere.
Plane A at 0 speed will drop from 20000 feet and meet Plane B.
Plane A is pulled by the force of gravity.
Plane A has 20000 units of Potential Energy.
Plane B will rocket upward with 700 knots from zero alitutde to meet Plane A.
Plane B has 700 units of Kinetic Energy.
Is it true that since Plane A and Plane B start out with the same Es or the same level of Specific Energy and that they will meet at the half way point or 10000 feet at the same Energy State or Es and therefore the same speed?
I think this works out with logic.
I see no need to calculate.

Practical application of Es or Specific Energy information ends at this mid way point or much sooner.

The Pilot of both Planes are on a suicide mission for they have no possible way to alter their course. Specific Energy calculations dictate a planet without atmosphere, and no propulsion.
Scotty from Star Trek beamed those two planes onto that planet earth minus the atmosphere and into their repsective conditions; one at 20000 feet at 0 velocity and the other at 700 knotts at 0 altitude.
Gravity pulled Plane A straight down.
Plane B had a purely vertical trajectory.
Both planes were lined up relative to each other and the fight ended at 10000 feet when both planes hit.

Ps or P sub s allows us to add an atmosphere on the planet and engines on the planes.

It seems to figure, again by logical deduction, that if both planes were identical then the addition of engines and atmosphere would not change the relative states of energy between Plane A and Plane B and therefore these two planes will meet at 10000 feet.

How can we define; "Identical"?

Keep in mind that our present combat condition does not include any factor of lift generated by wings, unless drag is counted as a negative force of lift.

What happens if "identical" is defined as two very heavy planes with very small engines?

WWMaxGunz
03-20-2004, 12:41 PM
Get yourself a HS physics book and look for the chapters on Mechanics and/or Motion. Read the sections and do the homework. Check your answers against the ones in the back of the book. If your answers are different, go back step by step till you find out what you did wrong and maybe what you thought that got you there.

700 knots straight up = 700 units of kinetic?
And 20000 feet up = 20000 units of potential?

Are you smoking something really good?
Or perhaps you have a degree in english or art?


Neal

JG14_Josf
03-20-2004, 01:17 PM
Neal,

Thanks for the suggestion, no thanks on the insults.

I have little desire to learn math, and a lot of desire to learn fighter combat.

"Fighter Combat"
by Robert Shaw

page 394

""Kinetic energy" is the energy of speed."

and

"Altitude, therefore, may be thought of as "potential energy""

Why do you continue with the insults?

I am not smoking anything, is your desire that I return your derogatory statements in kind?

Moderators please take note here on this thread that despite repeated and obivous provocation my posts remain civil.

clint-ruin
03-20-2004, 01:44 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by JG14_Josf:
Neal,

Thanks for the suggestion, no thanks on the insults.

I have little desire to learn math, and a lot of desire to learn fighter combat.<HR></BLOCKQUOTE>

From memory you need to have done 3Unit [highest offered by most non-selective schools] math in highschool to stand a good chance of admission into the RAAF :&gt;

Unfortunately a lot of this does come down to raw physics. People aren't trying to be obtuse or brush you off, it's just that any analogy is only going to go so far in describing the basic physical properties of an object going through the air. The sites I linked a few pages ago dealt with:

induced drag

calculating drag / effects of gravity on mass in a specific atmospheric density

and
the relationship between mass, drag, and gravity

The problem you are trying to solve is basically trying to work out the relationship between an object with greater mass and thrust vs an object with less mass and thrust, but also less drag.

Unfortunately the maths involved requires you to get into at least the basics of classical mechanics.

If you don't want to hit the books, there's some concise definitions here:

http://en.wikipedia.org/wiki/Newton%27s_laws_of_motion

http://en.wikipedia.org/wiki/Motion

http://en.wikipedia.org/wiki/Force

http://en.wikipedia.org/wiki/Mechanics

Reading through those should at least get you a nice enough collection of links to study what you're interested in at length. I know you probably don't want to go blind or mad doing equations about it, but as I said, on one hand you have ill-fitting analogies and on the other hand there's actually understanding the physical relationships involved here.

edit: munged urls

http://home.iprimus.com.au/djgwen/fb/leninkoba.jpg

[This message was edited by clint-ruin on Sat March 20 2004 at 01:05 PM.]

[This message was edited by clint-ruin on Sat March 20 2004 at 01:06 PM.]

Aaron_GT
03-20-2004, 02:18 PM
I have to admit that I have
a degree in physics. I've
been too lazy so far,
though, to do the research
to fill in some of the
gaps in the parameters, set
up the required differential
equations and try to solve
them for distance. Prop
efficiency and induced drag.

With regard to the potential
energy example,

E=fd=mgh

Since we are comparing
planes of the same mass in
your example we can
compare energy per unit mass

so at 20,000ft (6000m)
the energy 6000x10=60kJ

So we have 0.5v^2=60kJ
or v=sqrt(120000) =
346ms-1, or about 1200km/h
or just over the speed
of sound at sea level.

Aaron_GT
03-20-2004, 02:49 PM
The two planes will pass
each other at an altitude
of 4500m at 175m/s, about
17.5 seconds in a 35 second
long maneuver.

JG14_Josf
03-20-2004, 02:58 PM
Clint_ruin,

The problem I am trying to solve may be what you think it is and then again it may not be what you think it is, and I mean this with all sincerity and frank honesty.

The Spitfire vs Fw 190 comparison is a side issue and I really don't see any need to look any further than the combat pilot accounts I find in the books that I have to form my opinion as to how these planes actually did stack up in history.

The effects of weight on aircraft performance is a subject that has held my interest for some time now and my quest to understand this relationship is driven by it's application to combat tactics. In order for me to better understand the effects of weight on combat performance I find use in writting out my thoughts and I find use in minimizing the variables.
Sometimes I find use in what other people post on these boards, and other times I find only confusion, and then there are those who must resort to insults.

A plane in ridge lift offers my sense of comprehension a constant, a point of reference.
A plane in ridge lift is stationary relative to the earth. You can stand next to it and watch it move as conditions change. Add weight to the plane in ridge lift and what happens?

I don't expect anyone to see my perspective, but I do find it odd that other people tell me my perspective. How can anyone know my perspective if they don't ask? It suggests to me that confidence can be misleading and reading between the lines is prone to error.

The Specific energy example is another basic form of inspection into the problem. It eliminates a lot of variables. I don't care to crunch the numbers. Shaw has a neat chart that shows this altitude/speed energy relationsip.

Es, however is very limited in scope.

So what is wrong specifically with my questions that they must be ignored, cast out as irrelevant?

It seems clear to me that my questions are simply irrelevant to you because you do not understand my perspective. True or false?

When the Moderators find reason enough to banish me from posting then I'll stop.

Meanwhile this board offers me a place to bounce my thoughts around to see what comes back. I can suffer the insults and I can try my best to communicate when communication becomes difficult.

The title Post "Spit FM" inspired my responses that are germane since weight is a factor in determining performance. That is not to say my perspective suggests that wieght is the only determining factor.

It does seem to figure however that if the Combat pilots flying the Captured FW were able to out climb the Spit and if the Fw was in fact heavier than the Spit then there is all the more reason to suggest that the Fw would accelerate faster in a dive.

JG14_Josf
03-20-2004, 03:15 PM
Aaron_GT,

My hypothetical example Plane A and Plane B on Earth with no atmosphere are taken from a constant Es chart in Fighter Combat.
The chart is not exact but one constant line of Specific energy starts at 20,000 feet and then arcs down somewhere around 700knots.

Is it not true that since both planes have the same level of specific energy that they will meet at the half way point?
Since this is an imaginary situation where drag and weight are not a factor, where no atmosphere exists, the only force acting upon the speed of the one going up and the plane falling down is gravity.
Is it not true that an Es chart is only going to show comparative energy levels in a line parrallel to the force of gravity?
This is why my comments suggested the two planes being compared were one on top of the other pointing at each other and the combat situation would end in a collision.

It serves me to always think toward the goal of air combat reference. I am not interested in math, except as it serves to illuminate confusion in Air Combat tactics.

Robert Shaw wrote a chapter on Energy Maneuverability and his chapter begins with the Es or Specific Energy equation, chart, and explanation.

I think that my take on his explantation of the use of Es, written here on this topic, is correct.

My question concerning where the two planes will meet along the Es chart, i.e. half way, is a genuine unknown for me. I think however they would meet half way since each starts out with the same specific energy.

Aaron_GT
03-20-2004, 05:49 PM
Sorry I had read 700 knots
in you previous post as 700
km/h. 700 knots is around
1200 km/h, so your calcs
on sea level speed are
correct.

Also I made a calculation
error in my analysis

For the descending plane
h=6000-gt^2/2

For the ascending plane
h=gt^2/2

so we have h being the same
when they pass
6000-gt^2/2=gt^2/2
or gt^2=6000
t=sqrt(6000/10)=24.5

h=gt^2/2=3000m

So you were correct - they
cross at the mid point in
height (makes sense - same
k.e. and p.e. at this point)

JG14_Josf
03-20-2004, 06:28 PM
Aaron_GT,

Thank you very much for the clarification.

Please understand that I do not expect anyone to answer, and that my following words are meant to communicate ideas, even if I am only practicing the typing part of this exercise in communication.

The relevance to this thread topic continues to be Fighter combat performace.

Oleg may use accurate data to simulate these planes and his product may reflect the data he uses. It is the disparity between his product and historical record that inspires my need to understand these physical relationships.

I want to know why the discrepencies exist and I want to know how any errors may effect the application of real world tactics such as are described in Shaw's book.

The Fw 190 vs Spit matchup in particular is ineresting to me on this subject because so many accounts have crossed my attention that describe the Fw 190 as a 'superb' dog fighter against the Spitfire. Specifically the references I have describe in detail what appears to be the same tactical employment of Energy tactics in combat. This type of combat utilizes vertical manuevering and is not to be confused with Hit and Run tactics or to use the Sim Game vernacular 'Boom and Zoom'.

From that point in Shaw's Fighter Combat Book where he describes the concept and application of Specific Energy he moves on to Specific Excess Energy.

Aaron_GT
03-21-2004, 01:44 AM
I think people are still
reading more into pilot or
AFDU reports than is
warranted, or rather taking
parts out of context.

Roughly,
a=T/m+sin(p)g-D/m

Thrust decreases as speed
increases but drag increases

For small increases in speed
drag is constant. Drag also
depends on size but surface
area increases less rapidly
than mass so larger objects
will tend to have less drag
per unit mass (D/m)

So when beginning a dive
power loading is the
important factor, but
ultimately drag does.

Down low the engine powers
are easy to calculate by
looking at spec sheets. We
should see planes with poor
power loading at low
altitudes do poorly
initially. This is what we
see - seems to be ok there.
There are no long dives at
low altitude so drag
increase does not dominate

At high altitude too the
plane with the better
powerloading should win
initially too. The
difference is that a high
altitudes the P47 has a good
power loading compared to
other planes so wins
initially.

In the long run the plane
with less drag per unit
mass will win as drag will
tend to dominate.

In FB few people get up to
high alt so may not operate
in the region where the P47
has better powerloading than
others but have read about
the P47 pulling away in
dives without noting that
the reports were about high
alt engagements. So seeing
the P47 not win in dives low
down the assume FB is wrong
when it isn't

Now in the above I should
have called it excess
powerloading - i.e. it
assumes the engine is not at
full power and you can
throttle up

If you are at max level
speed, the same as another
plane then initially (drag
not changing much) both
planes will tend to drop
at the same rate until drag
dominates. There is no
excess power.

I hope that helps.

JG14_Josf
03-21-2004, 11:21 AM
Aaron_GT,

I don't know who are the people that read too much into pilot and or AFDU reports but for my understanding of the purpose of language the idea is to communicate with precision so as to leave the smallest room for error, to leave the least room between the lines, in effect to communicated effectively.

Alfred Price's Book appears to see things in this manner. Read, if you care, the following example and see if it applies to my statement above. Specifically see if the Author is trying to express the idea that communication needs to be precise in order to be effective.

"Following initial flight trials at the Royal Aircraft Establishment at Farnborough in July 1942, the captured Focke Wulf 190 flew to the Air Fighting Development Unit at Duxford for tactical trials. The resultant report, issued in August 1942 and reproduced below almost in its entirety, is a model of what such an intelligence document should contain. In places the language was complimentary in the extreme. The reader should bear in mind that these are not the words of a Focke Wulf salesman trying to boost his firm's product, but those of an enemy force to give an opponent grudging admiration in time of war."

Then on page 51 the above mentioned report states:

Dive
"The Fw 190 is faster than the Spitfire IX in a dive, particularly during the initial stage. This superiority is not so marked as with the Spitfire VB."

Manoeuvrability
"The initial acceleration of the Fw190 is better than the Spitfire IX under all condition of flight, except in level flight at such altitudes where the Spitfire has a speed advantage and then, providing the Spitfire is cruising at high speed, there is little to choose between the two aircraft"

Although the language above would fail to supply a flight sim producer with the required information to construct a flight model it is however the information that contemporary Combat Pilots considered to be vital for their survival.

The language is clear and unmistakable. Either those pilots actually did find the Fw190A-3 to be superior to their own planes in those specific areas of performance or the book is a falsification.

There is little room to read between the lines of the words written on that report.
Example:
'The Fw190 is faster than the Spitfire in the dive, particularly during the initial stages'

A British Combat Pilot or even a Flight Sim Combat Pilot reading this language would know what was being said.

If there is room to interject extra meaning into those example words then the next communication closes that space even further:

'The initial acceleration of the FW190 is better in all conditions of flight'

The Combat Pilot will know something valuable from reading those words if the information contained in those words is true.

I guess a person can find all kinds or reasons as to why those words could be falsified. But the same application of verification should apply to any information. Which leaves us with the need to have examples of these planes in our hands so we can test them ourselves, but even in this regard we fail because the planes we may aquire now are not the planes those pilots had then, and it would be difficult at best for any of us to aquire the same level of skill that those pilots had during that time.

Why those reports don't describe the game we play is not going to be an easy question to answer, but if you do not understand the validity of the question then you will never understand my perspective.

Aaron_GT
03-21-2004, 11:31 AM
"I don't know who are the people that read too much into pilot and or AFDU reports "

Not a reference to you!

SkyChimp
03-21-2004, 11:59 AM
From:

Focke-Wulf Fw 190 ‚"Long Nose‚"Ě: An Illustrated History of the Fw 190 D Series
Dietmar Hermann

Lt. Ossenkopp stated of the Dora-9's dive capability:

Spitfire: The D-9 was better in level flight, climb and dive.

Tempest: The D-9 climb and tuned better, but was inferior in a dive.

Mustang: The Mustang was rather faster in a dive.

Thunderbolt: We were hopelessly inferior in a dive. Never try to dive away from a Thunderbolt.

While this says nothing of prolonged dives, it's clear the Germans (at least this German) thought the least of the Spitfire's dive capability.

Regards,
SkyChimp
http://members.cox.net/us.fighters/skychimp.jpg

Aaron_GT
03-21-2004, 04:40 PM
Skychimp,
At high altitude that would
be true for the P47 as it
had good powerloading at
high altitude due to the
turbosupercharger. It
wouldn't be the case at low
altitude as there the P47
power loading was
indifferent. The Luftwaffe
would be encountering P47s
most at high altitude so
that seems correct.

The P51 had lower cd0 at
cruise, and different
supercharger arrangements
so may well have had more
excess power at high
altitude than the Spit (
which Spit version?). Also
with a lower cd0 drag
would build up more slowly
until high mach numbers. So
it seems entirely possible
that the P51 could outdive
some or all Spits in high
alt combat conditions. It
would be interesting to
know if this is also true
of the Griffon Spits
(faster than the P51B,C,D
at high alt)

SkyChimp
03-21-2004, 06:16 PM
Possibly Aaron, but no fighter is going to dive for very long at full throttle. In any sort of extended dive, the pilot would have to throttle-back to keep from overrevving the engine.

I think there is some conception on this board that the entire dive was done at full throttle. Maybe very, very short ones. But diving at full throttle for any significant length of time was a good way to lose a prop, strip a gearbox, or otherwise damage the engine.

Regards,
SkyChimp
http://members.cox.net/us.fighters/skychimp.jpg

JG14_Josf
03-22-2004, 10:35 AM
Ps=[T-D/W]V

Please excuse the limitations of the communication medium, the above equation is meant to show the Specific Excess Power Equation.

Back to Shaw's explanation of Energy Manueverability; Es or Specific Energy is limited in scope. Fighter performance comaprisons that utilize Es can only illuminate conditions of Altitude, Speed, and Gravity.
The example Plane A having the same Specific Energy State at 0 velocity and 20,000 feet has no energy advantage over Plane B at 0 Altitude and 700 knots.

Es limits the scope of comparison so greatly that the only application of this data involves one plane above the other since the equation provides no physical capability to maneuver and no allowance for a vectored or angled force of gravity. True or False? (I'm just thinking and writing and hoping communication does occur)

Ps or Specific Excess Power is the next formula mentioned in Shaw's book on the subject of Energy Maneuverability in his Chapter titled: Appendix Fighter Performance

With this Ps formula a Fighter Pilot can quantify a value for Energy Maneuverability, the pilot can take any combat situataion and from one moment in time he can look ahead to see how his Plane can stack up against his opponents plane with a Specific number that will predict a future relative energy state.

This number is applicable in our Earths atmosphere and can be used to compare real planes in real time.

This number must be applied to an Es value or at least to a specific relative Altitude since Altitude is not specified in the Ps equation.

In other words the Fighter Pilot does not have the complete combat picture when armed only with a relative Ps number. The pilot with a high Ps number has a greater potential future energy advantage over the opponent but not if the opponent is much higher.

Ps=[T-D/w]V

What is the effect of weight on this relative combat relationship?

If Ps, T, D and V were held constant.

If w were expressed as a factor known as 'rate of change'.

What then would be the factor of 'rate of change' for Ps?

Please correct errors in the following deductions for my math is not good and it only stands to reason from my limited perspective that as weight increases the value for Specific Excess power decreases.

Therefore if Ps decreases with increases in weight and if Velocity is held constant then altitude must drop.

If the rate of change where weight is increasing causes a decrease in the rate of change for Ps then as more weight is added the plane drops altitude at a greater rate.

Heavy planes dive faster.

On the other hand if the rate of change for weight dropping in value causes an increasing rate of change for Ps then it stands to reason that;

Lighter planes climb faster.

Aaron_GT
03-22-2004, 10:36 AM
"Possibly Aaron, but no fighter is going to dive for very long at full throttle."

Absolutely true.

My point is that in the initial stages
of a dive excess power loading is important,
but that as speed increases, it is aerodynamics
that dominate (especially if the engine has
to be throttled back).

It is just that I think people forget that
people read about the superior dive acceleration
of the P47, forgetting that this relies on
excess power loading, and that this is only
an advantage to the P-47 at high altitude.
Too many people expect it to be able to
accelerate quickly in a short dive at low
altitude too. At low altitude it has a low
power loading compared to other planes. The
other planes just don't have the ability
to hold horsepower as altitude increases.

Aaron_GT
03-22-2004, 10:46 AM
"Heavy planes dive faster."

All other things being equal, with no
critical mach issues, yes. Also at high
speeds (when drag dominates) they will
also accelerate faster in a dive. In the
initial parts of a dive from lower speed,
excess power loading will dominate.

At low speeds (in a relatively low speed
sustained climb) then drag will not be
so important, but power loading will be.
But it's not the mass of the plane that
is important, but rather than power loading.
(Well, also wing loading as well, but
you can have a light plane with high wing
loading and vice versa).

In a zoom climb (i.e. a significant portion
of the climb is at high speed) then the
heavier plane should win out (other aerodynamic
and thrust factors being equal) as at high
speed drag per unit mass dominates, and the
drag per unit mass of a large body will tend
to be lower. At the top of the zoom climb
it gradually turns into a low speed climb.

For a spherical body of constant density the
drag per unit mass scales with 1/r where
r is the radius of the body. Planes are more
complex, of course!

JG14_Josf
03-22-2004, 11:39 AM
Aaron_GT,

I am somewhat confused as usual, and it seems important from my perspective to clarify your post that started with this quote:
"Heavy planes dive faster."


Is it true that if T,D, and V are held constant that the rate of change for w is inversely proportional to the rate of change for Ps?

Is it also true that if T,D, and V are held constant that the rate of change for Ps is inversely proportonal to the rate of change in
altitude?

Is it then true that if a combat plane did nothing but dump ballast that it would climb and if it dumped a lot of ballast it would climb fast?

And therefore it would be true that if a combat plane took on weight it would dive and if it took on a lot of weight it would dive faster.

Is it also true that if the above relationship was true that it would always be true regardless of the speed at which the plane were traveling at the time the weight changed?

In other words the inverse relationship of the rates of changes between weight and altitude remains constant in the physical world. True or False?

Aaron_GT
03-22-2004, 01:03 PM
I think you are confusing yourself a bit
with the whole ballast issue.

What I am talking about are classes
of planes. E.g. a large plane tends
to be a massive one. If planes were
spheres then the drag per unit mass
would scale inversely to the radius
of the sphere. Thus by analogy the
drag per unit mass of a plane tends
to follow a similar relationship all
other things being equal.

If you think of it in energy terms,
the kinetic energy is 0.5mv^2, and
the drag is roughly dependent on
surface area, thus drag per unit energy
is less for a massive plane, as energy
scales linearly with mass. However
drag only assumes paramount importance
as speed increases, as drag tends to
scale with the square of the speed.

At low speeds power loading and lift
will dominate in climb speed. Power
loading, given the same engine, will
often favour lighter planes.

With regard to your ballast dropping
example, the plane will suddenly experience
increased lift relative to the force of
gravity on it, and it will also experience
a better powerloading. However it has just
dumped a load of energy, 0.5kmv^2 where k
depends on the amount of mass it just
dropped. If it is in a zoom climb (drag
is dominant) then dropping the ballast will
harm its climb. Since you have experience
of gliders, you have more experience of the
low speed regime in which the force of
gravity dominates, In this regime kinetic
energy is low, and dropping ballast will
ultimately help.

So it depends on the regime in which the
plane finds it in whether being light
(relative to lift and thrust - a heavy
plane with lots of lift and thrust will
climb better than an underpowered light
plane) may be an advantage or disadvantage.

Light planes with a comparartively high
lift are still able to climb poorly - just
look at WW1 planes as an example. The reason
is that their powerloading was very poor.
Zoom climb wasn't really available to them
as they could not achieve high speeds (high
kinetic energy) due to aerodynamic and
structural considerations.

JG14_Josf
03-22-2004, 02:16 PM
Aaron_GT wrote:

"I think you are confusing yourself a bit with the whole ballast issue."

I on the other hand think I am clearing my mind with the Ballast thing by making all variables constant except the one in question.

In this manner it seems clear, at least to me, that the effect of the one remaining variable is shown for what it is and not what it can be as a result of the combination it has with other forces.

Specifically my perspective relates to the use of this understanding to compare the combat effectiveness of airplanes.

Shaw and Boyd are pruported to be knowledgable in this area, and they both have a direct association with the Specific Excess Energy formula.

For this reason it seems appropriate to use that formula to work out the relative effect of weight when comparing the relative Combat performance of Airplanes.

For this reason my specific questions concering that specific formula are aimed toward a more tanslucent perspective regarding the effects of weight on Aircraft Performance.

Math being what it is I thought the specific question could be answered with a yes or a no.

Again it seems to figure that in the Ps formula:

Ps=[T-D/w]V

If T,D, and V (&lt;-Edit)* are held constant does w have an inverse rate of change relationship with Ps where increases in weight cause a decrease in Specific Escess Power and visa versa?

Now if that is know as true then it seems to me this fact can be applied to the Es equation.

Since Ps has no value all by itself since Ps does not include any reference to altitude then it seems to me that any factor of Ps must be applied to Es.

Is it not true that Ps and Es have a direct relationship? Increases in Ps will increase Es and visa versa?

Therefore, if incresase in w cause decreases in Ps then those decreases in Ps will decrease Es and if Es includes a constant value for V then Altitude must decrease.

Therefore, increases in w when T,D, and V are held constant will decrease altitude.

So, for my own personal sense of clarity my question is:

For the mathematical formula for Specific Excess Power does w have an inverse rate of change relationship with Ps if T,D, and V are held constant.

Although this math problem is not simple for me I had hoped someone else reading this could come up with the answer.

P.S. I am not able to realize the condition if in fact the answer has already been reported.

Perhaps a quote of the question followed by either the single word True or The single word False could suffice to confirm the answer.

Example:

___________________________
"The Specific Excess Power equation shows an inverse relationship between the rate of change of w and the rate of change of Ps when T,D, and V are held constant"
__________________________

True



or


___________________
"The Specific Excess Power equation shows an inverse relationship between the rate of change of w and the rate of change of Ps when T,D, and V are held constant."
____________________

False


Ps increase or decrease= [T constant - D constant/w decrease or increase]V constant

What is the mathematical symbol for constant?

I think rate of change is a triangle.

Can an inverse relationship have a symbol?

* Edited V in place of the W which was an error

[This message was edited by JG14_Josf on Mon March 22 2004 at 01:45 PM.]

[This message was edited by JG14_Josf on Mon March 22 2004 at 01:47 PM.]

JG14_Josf
03-23-2004, 05:43 AM
If thrust, drag, and velocity are held constant and if weight is changed and if Ps changes inversely proportional to the change in weight then when Ps is applied to Specific Energy the plane will decend as weight is increased.

If thrust, and drag were held constant and if Ps changes inversely proportional to changes in weight then perhaps the plane would slow down as weight increased if Altitude is held constant.

Increases in weight decrease Ps and while velocity, thrust and drag are held constant the negative values of Ps apply to the energy of altitude. The plane accelerates toward the earth.

Increases in weight decrease Ps and while altitude, thrust and drag are held constant then the negative values of Ps apply to the energy of velocity. The plane decelerates.

If the above is true then how does the ratio of rate of change between weight and altitude compare to the rate of change between weight and speed?

If rate of decrease in altitude resulting from increases in weight is high compared to the rate of decrease in speed resulting from increases in weight then wouldn't the higher rate of change of altitude result in a net acceleration due to gravity or in other words a net acceleration would only occur when the plane pointed the nose down as a result of increases in weight.