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XyZspineZyX
10-10-2003, 02:52 PM
Gentlemen,

Pursuant to US M2 .50cal MG dispersion, the following data is taken from Department of the Air Force AF Manual 335-25: Fighter Gunnery, dated December 1950. It covers the following a/c - F47, F51, F80, F82, F84. I invite you to read the following and draw your own conclusions regarding accuracy and lethality of this weeapon in aerial gunnery.

The 100 pct dispersion value of the M2 .50cal was 8 mils in aerial gunnery application. In USAF parlance, an angular measure of one mil is equivalent one foot at 1000 feet.

At a range of 1000 feet (333 yards), 100 pct of the bullet strikes from a .50cal MG will therefore fall within a circular area 8 feet in diameter centered upon the point of aim. By the law of ballistic dispersion, if 100 pct of strikes fall within 8 mils, then 50 pct of bullet strikes will fall within a circular area of 2 mils (2 feet) diameter. 75 pct of bullet strikes will fall within a circular area of 4 mils (4 feet) diameter.

In the case where all guns of a fighter are point harmonized, then all the individual gun dispersion circles will be super-imposed upon one another at the point harmonization range. Assuming a 2 second burst of fire from eight x M2 50cal firing at 720 rpm each at a point harmonization range of 333 yards, 96 rounds of .50cal will strike within the two foot diameter circle of the 50 percent zone, i.e. - about 30 rounds per square foot within that circular area. To put this in perspective, it would equate to about 25 .50cal bullets coming at you through the glass screeen of your average 17-inch monitor. See below regarding the opinion ofthe USAF that this degree of fire concentration was overkill.

The USAF appears to have frowned upon point harmonization for the generality of their fighter pilots, who were not necessarily skilled marksmen. Here is what the manual says about harmonization -


QUOTE -

Although point harmonization results in a heavy concentration of bullets at a certain range, it produces excessive dispersion at others. The heavy concentration of bullets at a selected range is not always desirable, because the density of the concentration is in excess of that required. This is inefficient use of available fire power and requires too many refinements in aiming.

For a superior fixed gunner, point harmonization is probably the best type. For the average pilot, a pattern-type harmonization is more desirable because it compensates for minor sighting errors.

-snip-

Such a harmonization fixes the sight line approximately in the center of the projectile pattern throughout the effective range when the aircraft is flown at the basic harmonization speed. This relieves ths pilot of the need to calculate the projectile drop within the limits of effective range. The most effective range for harmonization purposes is considered to be 2,000 feet.

- UNQUOTE

To get a sense of the nature of a pattern harmonization, imagine six overlapping circular dispersion areas whose individual centers would form a regular hexagon when connected by straight lines.


Blutarski editorial comment -
This same gun, in 6 or 8 gun batteries, proved lethal at ranges up to 700 yards with the K14 gunsight. IMO, the M2 50cal was an accurate and powerful weapon.



Blutarski

XyZspineZyX
10-10-2003, 02:52 PM
Gentlemen,

Pursuant to US M2 .50cal MG dispersion, the following data is taken from Department of the Air Force AF Manual 335-25: Fighter Gunnery, dated December 1950. It covers the following a/c - F47, F51, F80, F82, F84. I invite you to read the following and draw your own conclusions regarding accuracy and lethality of this weeapon in aerial gunnery.

The 100 pct dispersion value of the M2 .50cal was 8 mils in aerial gunnery application. In USAF parlance, an angular measure of one mil is equivalent one foot at 1000 feet.

At a range of 1000 feet (333 yards), 100 pct of the bullet strikes from a .50cal MG will therefore fall within a circular area 8 feet in diameter centered upon the point of aim. By the law of ballistic dispersion, if 100 pct of strikes fall within 8 mils, then 50 pct of bullet strikes will fall within a circular area of 2 mils (2 feet) diameter. 75 pct of bullet strikes will fall within a circular area of 4 mils (4 feet) diameter.

In the case where all guns of a fighter are point harmonized, then all the individual gun dispersion circles will be super-imposed upon one another at the point harmonization range. Assuming a 2 second burst of fire from eight x M2 50cal firing at 720 rpm each at a point harmonization range of 333 yards, 96 rounds of .50cal will strike within the two foot diameter circle of the 50 percent zone, i.e. - about 30 rounds per square foot within that circular area. To put this in perspective, it would equate to about 25 .50cal bullets coming at you through the glass screeen of your average 17-inch monitor. See below regarding the opinion ofthe USAF that this degree of fire concentration was overkill.

The USAF appears to have frowned upon point harmonization for the generality of their fighter pilots, who were not necessarily skilled marksmen. Here is what the manual says about harmonization -


QUOTE -

Although point harmonization results in a heavy concentration of bullets at a certain range, it produces excessive dispersion at others. The heavy concentration of bullets at a selected range is not always desirable, because the density of the concentration is in excess of that required. This is inefficient use of available fire power and requires too many refinements in aiming.

For a superior fixed gunner, point harmonization is probably the best type. For the average pilot, a pattern-type harmonization is more desirable because it compensates for minor sighting errors.

-snip-

Such a harmonization fixes the sight line approximately in the center of the projectile pattern throughout the effective range when the aircraft is flown at the basic harmonization speed. This relieves ths pilot of the need to calculate the projectile drop within the limits of effective range. The most effective range for harmonization purposes is considered to be 2,000 feet.

- UNQUOTE

To get a sense of the nature of a pattern harmonization, imagine six overlapping circular dispersion areas whose individual centers would form a regular hexagon when connected by straight lines.


Blutarski editorial comment -
This same gun, in 6 or 8 gun batteries, proved lethal at ranges up to 700 yards with the K14 gunsight. IMO, the M2 50cal was an accurate and powerful weapon.



Blutarski

XyZspineZyX
10-10-2003, 03:08 PM
I'm getting the impression that the .50 cals are moddeled correctly in terms of damage, piercing, etc, but that their dispersal patterns are quite off.

I've set my convergence around 400 meters now...rather than the 250 I usually find most effective for machine guns (including .303's) and that seems to help a bit...setting the convergence farther away seems to give me more firepower up close.

Its just odd that sometimes, with a Bf 109 centered totally in my sights (from a straight 6 o'clock position)...that I fire all 8 guns and hit with only a few shots (ranges being virtually the same in all situations) and at other times...in very similar circumstances...the plane not only gets hit but folds, breaks, and turns into a pile of smoking debris.

Nonetheless...practice is definately important. Cannons are much easier to get kills with than machine guns and after some work I have brought down many opponents online flying any fighter. But the fact remains that its a guessing game...last night I made 4 runs on a Stuka and at close ranges still did nothing more than take out his undercarriage. He had a fuel leak as well but no major damage.

http://freespace.volitionwatch.com/icefire/icefire_tempest.jpg
"Never in the field of human conflict was so much owed by so many to so few." - Winston Churchill

XyZspineZyX
10-10-2003, 03:16 PM
ye when i flew the real deal campaign, sometimes u sawed through planes, other times it was a pea shooter :\

XyZspineZyX
10-10-2003, 03:21 PM
Interessting! but isn´t it a bit theoretical?
For a single weapon on a fixed block of concrete? Especially wingguns are vibrating, and if you have 8 of this heavy MGs in your wing, all of the shooting, and creating vibrations, making the whole plane shaking??

Shooting tests of the MGFF with a low muzzlevelocity shown that at a range of 100m (300ft) 50% bullets hit within an area of 15/15cm, don´t know about the dispersion of the other bullets... but if you shot it from an Emil the dispersion will be much more!

JG53 PikAs Abbuzze
I./Gruppe

http://www.jg53-pikas.de/
http://mitglied.lycos.de/p123/Ani_pikasbanner_langsam.gif

XyZspineZyX
10-10-2003, 03:30 PM
yeah you are flying at hundreds of miles per hr u got wind vibrations and a lot of over stuff i think that the dispesil is fine

unless you have certified, verified data and proof of this or have actually flown the planes that stop your whineing!

XyZspineZyX
10-10-2003, 03:47 PM
Good point BLUTARSKI, I have very little issue with the DM of the M2, but the dispersion seems ... out of whack. Not horrible, but not right either.

Maybe it's just me wishing the cone would come to a better point.



http://home.earthlink.net/~aclzkim1/sitebuildercontent/sitebuilderpictures/il2sig2.jpg

XyZspineZyX
10-10-2003, 04:00 PM
Then remember you're target isn't sittitng still while you shoot at it, and you automatically increase your dispersion vs. a level steady speed firing platform as you attempt to draw the bead on the intended victim.

XyZspineZyX
10-10-2003, 04:18 PM
Remember that these figures are theoretical and for ground-based testing. When airborne there are a "few" factors coming into the equation which do affect dispersion in a negative way.


============================
The important thing in [tactics] is to suppress the enemys useful actions but allow his useless actions. However, doing this alone is defensive.

Miyamoto Musashi (1584-1645)
Japanese Samurai and Philosopher
(More than 60 Victories in Hand-to-Hand combat.)

XyZspineZyX
10-10-2003, 04:19 PM
I'm at work so I don't have my ballistic charts with me but people need to realize that firing a M2 .50 cal. does generate a bit of recoil but it can be handled by trained sniper. Now put that in an 8 ton aircraft travelling at 350 mph. The plane's energy and momentum far exceed the recoil of the M2 or for that matter 8 M2's. The plane's wings are not going to be flopping around like some people think. They may a bit if the plane is on the ground and not moving and I say that is what gives the M2 it's 8 mil dispernsion because the .50 caliber round is ballistically very accurate do to it's sectional density and ballistic coeffient. In other words if the best the .50 cal. could do was 8 mils it would not be used as a sniper round. Snipers' look for accuracy of a 1/4 mil or below. I could go on at length at what makes a certain caliber/weapon system accurate but I'll spare you the boring details. There is more to it than what most people think or what movies depict.

Fireman

XyZspineZyX
10-10-2003, 04:27 PM
fiestapower wrote:
- yeah you are flying at hundreds of miles per hr u
- got wind vibrations and a lot of over stuff i think
- that the dispesil is fine
-
- unless you have certified, verified data and proof
- of this or have actually flown the planes that stop
- your whineing!

From the context of the post, and the fact that it was an Air Force study about dispersion from specific aircraft, it seems probable to me that they were concerned about firing the guns while flying the listed aircraft.

If you do any reading about WWII aircraft at all, you are probably familiar with the phrase "stable gun platform." This expression has been used a lot in association with a number of US built planes, with the P-40 and P-47 leading the list. It means that when the aircraft is in the air, and the pilot gets the target centered in his sights from six o'clock and pulls the trigger, his bullets will hit the target.

When your aircraft is as heavy and strong as a P-47, even eight .50s will not create sufficient vibration to throw off your aim. You should give the design engineers a little credit for doing everything possible to keep the guns in their cradles. If they bounced around like some of you guys apparently think they did, the they would have torn the wings off the plane every time they were fired. The only mitigating factor would be the propwash from the target, and again, the sheer size of the Jug would minimize that. As for wing flex, that was usually associated with jamming the ammo feed, and the Jug never experienced that issue to the point of official notice, unlike early Wildcats or the A & B models of the Mustang.

It does appear to me that the .50 is undermodelled in the P-47, while it is not (or significantly less so) in the P-39, which had the synchronized guns firing through the prop (hence, at a lowered rate of fire). There does seem to be a prejudicial element at work here.

While there is good documentation that the Soviet 12.7mm and German 13mm MGs had a higher muzzle velocity and rate of fire, the fact is that in practice, they were generally used in only single and double mounts firing through the prop, which further limited their weight of fire (the number & total weight of bullets striking the target per second) in comparison to the 4, 6, or 8 .50 caliber wing mounted guns favored by the Americans. At 250m (almost 300 yards), the difference in muzzle velocities (and dispersion), was neglegible, and the number of guns on the target should be the deciding factor and the advantage should go to the P-47 or P-40, as it did in real life.

"Here's your new Mustangs, boys. You can learn to fly'em on the way to the target. Cheers!" - LCOL Don Blakeslee, CO, 4th FG, March, 1944

XyZspineZyX
10-10-2003, 04:28 PM
BLUTARSKI wrote:
- The 100 pct dispersion value of the M2 .50cal was 8
- mils in aerial gunnery application. In USAF
- parlance, an angular measure of one mil is
- equivalent one foot at 1000 feet.


That's most likely assuming no additional sources
of dispersion, such as wing flex, vibration in the
wings, etc, perhaps, as otherwise it would have
to be quoted with reference to the aircraft type.

RAF figures for dispersion of .303s at 400 yards
are about 2,5 times those quoted above, which would
be about twice that figure at 1000 feet, although I
don't know if the .303 Browning dispersion compares
to the .50 (the share the same basic design, though).

XyZspineZyX
10-10-2003, 04:31 PM
fireman1969 wrote:
- I'm at work so I don't have my ballistic charts with
- me but people need to realize that firing a M2 .50
- cal. does generate a bit of recoil but it can be
- handled by trained sniper.

A trained sniper has little to do with 6 to 8 guns
mounted, firing full auto, in the wings of a plane
though.

- Now put that in an 8 ton
- aircraft travelling at 350 mph. The plane's energy
- and momentum far exceed the recoil of the M2 or for
- that matter 8 M2's. The plane's wings are not going
- to be flopping around like some people think.

Actually one of the concerns the RAF had with going
to cannon was exactly that, and the effect of recoil
on wing flex and accuracy. If you can track down
Ogre's site (I can't remember the URL) he takes this
into account.

XyZspineZyX
10-10-2003, 04:37 PM
fireman1969 wrote:
- The plane's wings are not going
- to be flopping around like some people think.

This depends on how far the armament is located from the AC´s cg, wing construction (flexing under load, vibrations due to recoil, etc), and the amount and type of armament installed. If the line of fire does not extend through the cg, then the AC can actually start to jaw when firing, in case of variations in rate of fire for single guns or weapon malfunction. The accumulated recoil of a 3 second burst from a P-47 could actually slow down the AC´s airspeed.

============================
The important thing in [tactics] is to suppress the enemys useful actions but allow his useless actions. However, doing this alone is defensive.

Miyamoto Musashi (1584-1645)
Japanese Samurai and Philosopher
(More than 60 Victories in Hand-to-Hand combat.)

XyZspineZyX
10-10-2003, 04:41 PM
horseback wrote:
- If you do any reading about WWII aircraft at all,
- you are probably familiar with the phrase "stable
- gun platform." This expression has been used a lot
- in association with a number of US built planes,
- with the P-40 and P-47 leading the list. It means
- that when the aircraft is in the air, and the pilot
- gets the target centered in his sights from six
- o'clock and pulls the trigger, his bullets will hit
- the target.

There are several factors involved.

One is the stability of the aircraft in the air.
This is independent of the guns.

Factor two is the reaction of the aircraft as a whole
in relation to the recoil.

The third is the reaction of the wings in reaction
to the firing.

And this is without taking into account convergence,etc.

- When your aircraft is as heavy and strong as a P-47,
- even eight .50s will not create sufficient vibration
- to throw off your aim.

This is true. It is entirely possible that the aircraft
can be stable in this respect, but that vibration of
the guns in the wings have a significant negative impact
on the dispersion of rounds. For example, the Spitfire
had thin wings compared to the Hurricane, and apparently
one of the factors giving the Hurricane an advantage
as a gun platform was the relative stability of the
wing when firing 8 guns.

Look at Ogre's site if you can find it. One of the
demerits of 20mm cannon is the effect of recoil with
respect to wing structure and the additional dispersion
it imparts to the distribution of rounds. With .50s
the effect should be smaller than a 20mm cannon, but
I don't think you can dismiss the effect, even on
a large plane.

- If they
- bounced around like some of you guys apparently
- think they did, the they would have torn the wings
- off the plane every time they were fired.

The wings on many planes of the period flexed significantly
under load. They didn't often fall off.

- As for wing flex, that was usually
- associated with jamming the ammo feed, and the Jug
- never experienced that issue to the point of
- official notice, unlike early Wildcats or the A & B
- models of the Mustang.

With regard to the P51 it seemed to be a combination
of wing flex, freezing of feed lines, and the
cant of the guns over in the thin wing. The P47 wing
is thicker in absolute terms, requiring no cant. When
the P51 gun cant was removed the jamming went away.

- It does appear to me that the .50 is undermodelled
- in the P-47, while it is not (or significantly less
- so) in the P-39, which had the synchronized guns
- firing through the prop (hence, at a lowered rate of
- fire).

But with less issues with regard to vibration of
the wings, relative roll, and convergence. The P47
may have a bug with .50 effectiveness, but the nose
guns on the P39Q10 are not a fair comparasion. Probably
fairer is a comparasion between the two gun groups
on the B239, as you can fire wing or nose guns
separately. I haven't found a good way of setting up
a static target to see if there is a difference in
static testing. Even more so given the B239 is a tail
dragger.

XyZspineZyX
10-10-2003, 04:44 PM
it may not make a huge differnce but a fast moveing plane that is manovering trying to fire at another fast moving target is gonna really screw up aim and with the way the guns were set up would make it hard at some distance but i think all this wineing is that people with bad aims pratice or fly a plane with cannons

unless you have certified, verified data and proof of this or have actually flown the planes that stop your whineing!

XyZspineZyX
10-10-2003, 05:03 PM
http://www.cris.com/~reaper/gunnery/gunnery.html

for Ogre's site.

The analyses for the F6F don't include wing vibration,
buffeting etc and assume perfect targeting, so be careful
with those results - they would be upper bounds assuming
no effect of the aerodynamics etc of the aircraft.

Sadly I don't know what the axis units are in for the
comaparative study (including aerodynamic effects on
the aircraft) for F6F, Spit IX, and Fw190A

XyZspineZyX
10-10-2003, 05:08 PM
Aaron, et al -

These dispersion data are not from artificial ground-based bench tests. The 8 mil 100 percent zone was based upon observation of aerial gunnery and ground strafing test results. As such, they already reflect the influences of fire from an in-flight firing platform which do indeed diminish accuracy. A .50 caliber weapon firing under bench test conditions at 300 yards would produce FAR better accuracy results by several orders of magnitude. By way of comparison, a decent rifleman with a .30 caliber weapon can easily produce 6-inch groups at 200 yards. The .50 is a far more accurate cartridge than that under ground fire conditions.

When comparing ballistic accuracy between different caliber projectiles of the same overall shape, the determining value of merit is the ballistic co-efficient:

W
--
cd2

where W = projectile weight
c = co-efficient of form
d = projectile diameter (caliber)


A 50cal projectile weighs about 4.5 times more than a .303 caliber projectile. Co-efficient "c" cancels out of the equation when projectiles are of similar form, as they are assumed to be here. A quick calculation therefore gives a relative ballistic co-efficient superiority for the 50cal of about 1.667 to 1 versus the .303. This is why a .303 caliber weapon shows greater dispersion than a .50 caliber weapon at similar muzzle velocities.


Blutarski

XyZspineZyX
10-10-2003, 05:33 PM
BLUTARSKI wrote:
- way of comparison, a decent rifleman with a .30
- caliber weapon can easily produce 6-inch groups at
- 200 yards. The .50 is a far more accurate cartridge
- than that under ground fire conditions.

And such a shooter wouldn't even need to be decent. 10cm (4 inch) group at 150m with assault rifle is something decent shooters manage. Now such a guy with a good rifle and it'll be 1 inch at 200m.

- When comparing ballistic accuracy between different
- caliber projectiles of the same overall shape, the
- determining value of merit is the ballistic
- co-efficient:

Ballistics do not effect nearly as much as the innaccuracy of the weapon. Assault rifle has something like 50mm dispersion at 150m while a good bolt-action rifle chambered for the same round will shoot "in the same hole".

Automatic weapons do have significantly worse accuracy than single shots due to their moving breech construction. Especially when fired in full auto mode barrel vibration has negative effect in accuracy.

When you talk about automatic weapon that is connected to solid frame, also the vibration of the frame adds to the dispersion.


-jippo



Message Edited on 10/10/0304:34PM by Jippo01

XyZspineZyX
10-10-2003, 05:56 PM
BLUTARSKI wrote:
- Aaron, et al -
-
- These dispersion data are not from artificial
- ground-based bench tests. The 8 mil 100 percent zone
- was based upon observation of aerial gunnery and
- ground strafing test results.

How was the averaging done? The dispersion would
be different from planes such as the F84
(nose mounted) and F51 (wing mounted, thin wing).


-
-
-
-
-

XyZspineZyX
10-10-2003, 07:00 PM
Abbuzze wrote:
- Interessting! but isn´t it a bit theoretical?
- For a single weapon on a fixed block of concrete?
- Especially wingguns are vibrating, and if you have 8
- of this heavy MGs in your wing, all of the shooting,
- and creating vibrations, making the whole plane
- shaking??


Not theoretical. See my post to AaronGT. To put 8 mils dispersion in perspective, it is about the accuracy performance of a good early 19th century muzzle-loading smoothbore musket. The influence of an in-flight factors is already in that 8 mil 50cal dispersion value.


- Shooting tests of the MGFF with a low muzzlevelocity
- shown that at a range of 100m (300ft) 50% bullets
- hit within an area of 15/15cm, don´t know about
- the dispersion of the other bullets... but if you
- shot it from an Emil the dispersion will be much
- more!


Was this a ground-based bench test or an in-flight test?
In any case, 50 pct strikes within a 15cm diameter would indicate a 100 pct strike zone of 60cm diameter, otherwise equal to 6 mils.

While of lower muzzle velocity, the 20mm round is superior to the 50cal in ballistic co-efficient to approximately the same degree as the 50cal is superior to the .303. As an example of the influence of ballistic co-efficient, a 15-inch naval projectile fired at 2500fps will retain a greater velocity at 20,000 yds than a 12-inch projectile fired at 3000fps. Exterior ballistics is a complicated inter-relationship of different factors.


Blutarski

XyZspineZyX
10-10-2003, 07:09 PM
AaronGT wrote:
- With regard to the P51 it seemed to be a combination
- of wing flex, freezing of feed lines, and the
- cant of the guns over in the thin wing. The P47 wing
- is thicker in absolute terms, requiring no cant.
- When
- the P51 gun cant was removed the jamming went away


As further comment, the jamming problem experienced by early P51 with the canted gun installations was most commonly associated with high (3+) G firing conditions. Several solutions were tried, including the use of booster motors on the belt feeds, but the problem was not completely solved until the guns were re-mounted in more conventional vertical fashion.



Blutarski

XyZspineZyX
10-10-2003, 07:12 PM
... or was the data from a waist gunner on a B-17?

{{tosses in two cents}}

There is a lot of vibration with an airplane period (example the P-47):
-Four blade prop constantly buffetting the plane. A prop does not make a smooth blowing wind, but a helical pressure front that is contantly pounding the plane with every revoluntion.
-Torque can be cancelled out, but only at a specific speed/angle-of-attack, and air density. Change that and the plane wanders. The wander is small, just a fraction of a mil even, but it still happens.
-Angle of attack will change the vibrations in the wings (buffet)
-With eight, non-syncronized, non-compensated, .50 caliber machine guns firing there are several actions to throw the plane off of alignment:
--Dirty guns fire slower, one side can produce higher recoil forces than the other.
--Rate of fire can vary by G-loading and belt length. There was not a motorized loading system, these were gas operated weapons.
--Muzzle blast does change the aerodynamics over and under the wing, adding vibration.

It all adds up. I wouldn't put much faith in a 2 second burst from a P-47 hitting a 2 foot circle at 1000 yards 50 % of the time without computer controlled assist.

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

Comparing a 50cal military ball round out of an M2 machine gun to a modern .50 sniper rifle with match-grade ammo isn't even fair. That is like comparing a Chevy Camaro to a Can-Am racing car.These both may use the same ening block, but that is where they part company. One is a daily workhorse used for normal duty, the other very specialised and limited.



Message Edited on 10/10/0306:15PM by legodragonxp

XyZspineZyX
10-10-2003, 07:23 PM
Jippo01 wrote:
- Ballistics do not effect nearly as much as the
- innaccuracy of the weapon. Assault rifle has
- something like 50mm dispersion at 150m while a good
- bolt-action rifle chambered for the same round will
- shoot "in the same hole".

..... Agree. Comparing like to like, consider an AK47 versus a rifle of the same nominal caliber. Same bullet perhaps, but very different cartidges. The rifle will fire a full-power cartridge yielding much higher muzzle velocity. For the same bullet, a higher velocity will produce greater accuracy over range.
-
- Automatic weapons do have significantly worse
- accuracy than single shots due to their moving
- breech construction. Especially when fired in full
- auto mode barrel vibration has negative effect in
- accuracy.
-
- When you talk about automatic weapon that is
- connected to solid frame, also the vibration of the
- frame adds to the dispersion.

..... Also agree. No MG in automatic fire will produce accuracy results equivalent to single shot fire.Andthis is altogether due to vibration produced by the reciprocating elements of the breech mechanism. I understand in fact that screwing the traverse and elevation down too tight would actually INCREASE dispersion in a WW1-WW2 era rifle caliber sustained fire ground mount MG. The effects of vibration upon accuracy are considerable.



Blutarski

XyZspineZyX
10-10-2003, 07:39 PM
BLUTARSKI wrote:

- ..... Agree. Comparing like to like, consider an
- AK47 versus a rifle of the same nominal caliber.
- Same bullet perhaps, but very different cartidges.
- The rifle will fire a full-power cartridge yielding
- much higher muzzle velocity. For the same bullet, a
- higher velocity will produce greater accuracy over
- range.

No with the exact same round. Differences in construction can easily cause such difference. It is mainly due to, different breech construction(AK bolt will move while bullet is in the barrel even in single shot fire, while in bolt action rifles breech will remain closed) frame sturdiness, barrel length, all sorts of things really. On a rifle even a small thing as barrel touching the wooden parts can double the dispersion compared to free floating.


- ..... Also agree. No MG in automatic fire will
- produce accuracy results equivalent to single shot
- fire.Andthis is altogether due to vibration produced
- by the reciprocating elements of the breech
- mechanism. I understand in fact that screwing the
- traverse and elevation down too tight would actually
- INCREASE dispersion in a WW1-WW2 era rifle caliber
- sustained fire ground mount MG. The effects of
- vibration upon accuracy are considerable.


Yep, and even more important is the breech and bolt action. In addition MG's will have large tolerances built in them which aid reliability(temperature changes, moisture, dirt, ...) which will not help the accuracy either.

The mounting on a plane can make difference too. When Finns got the Fiat G.50, the pilots complained about the inaccuracy of the MG's. Problem was solved by building a proper mounting for the guns instead of the lousy original ones.


-jippo

XyZspineZyX
10-10-2003, 07:41 PM
AaronGT wrote:
-
- BLUTARSKI wrote:
-- Aaron, et al -
--
-- These dispersion data are not from artificial
-- ground-based bench tests. The 8 mil 100 percent zone
-- was based upon observation of aerial gunnery and
-- ground strafing test results.
-
- How was the averaging done? The dispersion would
- be different from planes such as the F84
- (nose mounted) and F51 (wing mounted, thin wing).
-

..... The 8 mil figure was presented as the 100 pct dispersion of an individual gun. Whether this was empirically derived or statistically calculated is not stated in the manual. The manual simply presents it as a useful overall M2 50cal dispersion value for aerial gunnery purposes. I don't disagree that this value might vary, depending upon the particular nature of a given gun mounting. But I doubt whether any such variation would be of a profound nature.

Another thing to consider regarding wing versus nose mounted guns is that any conceivable improvement in dispersion which might be obtained from a nose-mounted configuration would be offset to one degree or another by synchronization limits upon the rate of fire of that weapon (excluding those weapons firing through the prop-hub, of course).

I make no effort to argue that the 50cal was a sniper rifle, but it was clearly no blunderbuss. It was an accurate, effective, and easy to use weapon.



Blutarski

XyZspineZyX
10-10-2003, 08:05 PM
Also, another thing to consider is that no two rifle's/machine guns/pistols/mil-spec ammunition of even the same batch are the same. Every barrel has it's own unique harmonic vibration (which, grossly exaggerated "whips" the barrel), and standard mil-spec ammunition is not very consistent. Even in one of todays premier long range accuracy firing platforms (Barrett 99, bolt action), standard military ball, API, AP all produce inconsistent results at 200 yards. However, when firing hand loaded ammunition with consistent powder charges and match grade projectiles, it is very very consistent. The same effects are also apparant in other military rounds; 5.56mm NATO vs. handloads with match projectiles, the military loads aren't nearly as accurate.

XyZspineZyX
10-10-2003, 08:56 PM
BaronVonSnoopy wrote:
- Also, another thing to consider is that no two
- rifle's/machine guns/pistols/mil-spec ammunition of
- even the same batch are the same. Every barrel has
- it's own unique harmonic vibration (which, grossly
- exaggerated "whips" the barrel), and standard
- mil-spec ammunition is not very consistent. Even in
- one of todays premier long range accuracy firing
- platforms (Barrett 99, bolt action), standard
- military ball, API, AP all produce inconsistent
- results at 200 yards. However, when firing hand
- loaded ammunition with consistent powder charges and
- match grade projectiles, it is very very consistent.
- The same effects are also apparant in other
- military rounds; 5.56mm NATO vs. handloads with
- match projectiles, the military loads aren't nearly
- as accurate.


..... Quite so. Agree on all points. Gegree of ammunition QC, breech locking method (or lack), barrel length, barrel weight, free-floating, bedded, head spacing on MG's, even the temperature of the powder - all sorts of things can influence accuracy of shooting.

Although, you've got to agree that 50cal snipers firing high quality match grade ammunition have done some really good shooting at 1500 and even 2000+ meters in Afghanistan and Iraq.


Blutarski

XyZspineZyX
10-10-2003, 09:15 PM
I do agree, .50 sniper teams did some excellent work. Snipers also tend to load their own ammo.

XyZspineZyX
10-10-2003, 11:24 PM
.50s are so wrong b239 strongest, p40s then jugs? and damage models are way too strong in certain aircraft, how do I know this? Lots of research and collecting 9mm guncam reels since I was a kid. I have over 20 hrs of footage from all nations.

what are you going to tell us next a hurricane mk1 or iib couldnt shoot down 2 he111s?

Hopefully things will get sorted out, 190s yaks laggs la7s should take slightly less damage, a plane gets hit by any caliber its going to cause some serious damage, 1 .50 b17 gunners for example, do you think you would be able to down any plane in this game with 1 .50, or 303s on on the blenhiem nope

http://www.freewebs.com/leadspitter/lead.txt
Good dogfighters bring ammo home, Great ones don't. (c) Leadspitter

XyZspineZyX
10-10-2003, 11:37 PM
LeadSpitter_ wrote:

- you think you would be able to down any plane in
- this game with 1 .50, or 303s on on the blenhiem
- nope


Will MG-15 in Heinkel 111 do?

In fact it is way too easy in the game now. Especially for hand held weapons defensive MG's are way too easy to aim. Small MG's do really do damage, and can be used to mortally wound fighters. LaGG engine is invulnerable still, but for example La-7 and P-47 are quite doable, not mention Migs or 109's.


-jippo

XyZspineZyX
10-11-2003, 12:26 AM
I dunno for me at a range of .20 with 2.3 convergence I can fire at a la7 yak or 190 for a couple seconds seeing many many hit flashes ripping off elevator tabs and alieron tabs and they still out manuever you, even in short 1 second bursts same thing, in the la7 you hit a jug once it explodes into a million pieces or sheers off a wing with 1-2 hits,

offline is a totally different story ai bail from very light hits.

http://www.freewebs.com/leadspitter/lead.txt
Good dogfighters bring ammo home, Great ones don't. (c) Leadspitter

XyZspineZyX
10-11-2003, 12:29 AM
It all depended on the barrols, The M2-heavy has a 3 1/4 right hand twist, the Airforce mod had a full 4 right hand twist.
So...it depends really on who your suplier is ?

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http://home.comcast.net/~ick_352nd/

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XyZspineZyX
10-11-2003, 12:55 AM
fiestapower wrote:
- yeah you are flying at hundreds of miles per hr u
- got wind vibrations and a lot of over stuff i think
- that the dispesil is fine
-
- unless you have certified, verified data and proof
- of this or have actually flown the planes that stop
- your whineing!


Aparentaly you didnt read the Post FiestaPower hes not whining there having an interesting discusion
READ IT !!!



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XyZspineZyX
10-11-2003, 01:09 AM
Ok If all of this dispersion is true then why do yak Mig La Lag bullits fly out on a lazer like accuracy in a perfect straight line and are effective beyond 1km

Ive been shot down buy thoes lil white MGs of the yak3,
1 silver bullit from 1.2 km sure it was spray & pray & its happened more than once but imo @ 1.2km None of there guns should be able to hit especialy when Im in a 40 to 60 degree climbing angle & from 1.2km Come on ???

If the 50.s of the P47 were as deadly as thoes lil silver yak bullits well I think you know what Im saying.

IMO 50.s dispersion is a lil much compared to the lack of such in many other ac in this sim.

PS Im not whining either, I fly the D10 alot & like it very much thats just my opinion. On the Dispersion theory.

If theres going to be dispersion modled for 50.s why not for the others ?

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XyZspineZyX
10-11-2003, 02:37 AM
korean war mig aces say their 20 mil cannons were not able to hit a target past 300 feet away. on contrary they say the sabres 6 50s were able to damage and shoot down their migs at 3000 feet. easily. the dispersion on the jugs 50s is a joke . you dont have this problem in the b239 and p40. never. whats the real deal? the real deal is 8 50s on the jug should rip any plane to shreds in a few second due to the sheer number of hits....read original post to get an idea of the number of bullets. its astounding. if jugs were modelled correctly with their guns everyone would be flying it. and oleg doesnt want that

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Message Edited on 10/10/0306:42PM by RedDeth

XyZspineZyX
10-11-2003, 02:47 AM
RedDeth wrote:
- if jugs were modelled correctly with their guns everyone
- would be flying it. and oleg doesnt want that

Conversely however, the LW guns are also undermodeled it seems. Single 20mms did amazing damage to B-17s. Seeing that leads me to think that VVS fighters would have been ripped to shreds exceedingly easily (if you could score the hits that is). Far more so than what we see in game.

And - the Mk108 equipped A9 is one fierce opponent with the fire power to down almost anything in a very short burst, but not everybody is flying them.

XyZspineZyX
10-11-2003, 05:39 AM
Well, because of this thread I decided to try out a P-47...and it's not a bad plane. I set the convergence to 300 for everything, and went in qmb set up an ace 190A9, and tore him to shreds in no time flat. Seems OK to me. I typically fly 190's, so I was a little upset at how fast the thing succumbed to the 50's. Just my $.02