Calculated "base" dispersion of guns based on energy delivered

[HoHun]

Hi Charge,

>HoHun, the projectiles in high dispersion do not avoid the area in the middle of the hit pattern but spread randomly over it with the preference being in the center [...]

Correct. And the same is true for pilot aiming errors. To reap any benefit from a large-dispersion weapon - which concentrates its fire on the aim point, just like a low-dispersion weapon -, the pilot would have to involuntarily avoid the correct aiming point.

Only then the large-dispersion weapon's higher hit concentration out of the centre of the pattern would improve kill chances.

If the pilot's aim is not avoiding the correct aiming point, but merely inaccurate, the low-dispersion weapon's higher concentration of fire in the centre of the pattern makes it more lethal even if the aim is subject to errors.

>But if you hit the pilot, or a coolant, oil, or fuel line or radiator that is usually enough, depending on if the damaged a/c can handily RTB which was not the case for German a/c for example during BoB.

True :-)

>Obviously during the last stages of WW2 the experience had shown that the increase in speeds and amount of defensive armament in bombers required lots of damage in shortest time possible -thus the cannon armament became a necessity.

Well, the Luftwaffe actually had developed cannon from the mid-1930s on, and intended them as general anti-aircraft weapon, so I think your sentence could be misunderstood. If your main point is that the Luftwaffe would have been off worse in 1944 with machine guns instead of cannon, I certainly agree.

>I'd take a dangerous step here and claim that if the situation had gone to worse direction for the allies the US, too, would have had to introduce the cannons into aircraft participating in aerial battle.

Again, I agree. Using the 12.7 mm machine guns for air-to-air combat was a bit of a dangerous luxury - the RAF had actually been in a bad situation in 1940, which might explain their different weapon selection.

>Sorry, I went quite far from the original subject.

Well, you highlighted a new aspect of a much discussed topic, so it was an interesting digression :-)

Regards,

Henning (HoHun)

[Tony Williams]

A couple of points may be worth emphasising:

High dispersion only works if each individual hit is capable of inflicting significant damage. The RAF were forced to adopt a closer concentration of the .303 guns in the BoB (much against their will) because the damage inflicted by an individual bullet was usually small, so they had to concentrate a large number of hits in a small area to have much effect.

The aiming of most pilots in deflection shooting was CONSISTENTLY poor, in that they usually seriously underestimated the lead required. With a precisely accurate gun they would therefore have missed virtually every time. A dispersed set-up improved their chances of scoring SOME hits.

Tony Williams: Military gun and ammunition website and discussion
forum

[Roman1]

I was on a site checking out some things for CFS3 and found this. I thought that it might help you out. Here is the link.

http://www.avhistory.org/  
Go to Knowledge base drop down and then to "1% Standards" --> WW2 gun parameters.

Might be some info that can really help you out.

[HoHun]

Hi Tony,

>High dispersion only works if each individual hit is capable of inflicting significant damage.

I see your point, but my point is that even then, low dispersion works better :-)

>The aiming of most pilots in deflection shooting was CONSISTENTLY poor, in that they usually seriously underestimated the lead required. With a precisely accurate gun they would therefore have missed virtually every time.

Well, air combat is highly dynamic. It's not like an artillery duel where you set up the guns in fixed positions and then slug it out.

In air combat, the aircraft move in 3D, and it's rare that you get into a position where the target is static in the sights of the attacker for any length of time. As long as we're talking about manoeuvring tarets, that usually happens only if the defender is surprised or if he is attempting to run away in a straight line.

The amount of "static" dispersion is not a help in these situations since the attacker usually has the time to set up an accurate shot with a low aiming dispersion there, so a low-dispersion weapon means he can score more hits.

Number two of "Sailor" Malan's "Ten Rules" was: "Whilst shooting, think of nothing else, brace the whole of your body, have both hands on the stick, concentrate on your ring sight." Obviously, relaxing a bit would increase uncontrolled dispersion, which you'd usually want to avoid.

In a manoeuvring fight, "static" dispersion is not that important either because it's two-dimensional. It's easy for the pilot to create "dynamic" dispersion by handling of the stick and rudder if he needs it, and he can actually create one-dimensional dispersion by "hosing" the target along a certain axis.

For example, it's usually pretty easy to align the sight with the direction of flight of a crossing target. Estimating the correct lead is much more difficult. Firing a long burst on a collision-course attack without turning the aircraft will create a pattern that extends in time rather than in space (funny way to look at it, but still :-), and because the target has to fly through the pattern, it will probably get hit.

A more conventional example would be the target that's attacked with a tracking shot. Using "static" dispersion in a stationary situation, you'd hold your aircraft in a steady turn matching the target's. The pattern will not only extend fore and aft of your aiming point, which is useful if you don't know the correct amount of lead, but also left and right, which is not that useful since the aircraft fuselage is pretty narrow. (The wings are hard to hit as due to their shorter depth, they require even more accurate lead to hit.)

Using "dynamic" dispersion, you'd usually pull too much lead, start firing, and relax the stick while holding the trigger. That will create a pattern that extends just as far fore and aft as with the high-dispersion weapon, or even wider if you desire, but still is so narrow that you can align most of it with the fuselage which is the best target anyway.

For example, you might get a 3 m diamter "static" dispersion circle with a large-dispersion weapon. You'd cover the same 7 m^2 area with a low-dispersion weapon with a 1.5 m by 4.7 m "dynamic" disperion pattern, with the 4.7 m extension along the axis of the lead, increasing your hit chances by about 50% if your main aiming error is caused by the mis-estimation of the necessary lead.

It's much easier to do then to explain :-) In fighter pilot slang, you might describe it as "hosing down" the target, if you're familiar with that term.

Regards,

Henning (HoHun)

[Tony Williams]

Hi Henning,

I think what you are forgetting is that most fighter pilots in WW2 had very little (if anything) in the way of realistic firing practice before entering combat, gained little useful practical experience in combat shooting, and were usually in a blind panic then anyway. The most that could be expected of them was to point the sights at the target and fire. Only a very small minority had the skill and coolness to achieve success with any kind of deflection shooting - which is why something like 90% of all kills were achieved by 10% of the pilots.

Perhaps one of the pernicious effects of modern combat sims - where people can practice for hours in a stress-free environment - is that they make people devalue just how very difficult it was for the vast majority of WW2 pilots to shoot anything down. For the few experts a wide dispersion would be a nuisance because it would reduce the lethality of their fire. But for the vast majority, the 'shotgun' effect of a wide dispersion gave them a better chance of scoring hits. There is a very good reason why people don't go hunting birds on the wing with rifles - or even machine guns!

Tony Williams: Military gun and ammunition website and discussion
forum

[HoHun]

Hi Tony,

>I think what you are forgetting is that most fighter pilots in WW2 had very little (if anything) in the way of realistic firing practice before entering combat, gained little useful practical experience in combat shooting, and were usually in a blind panic then anyway. The most that could be expected of them was to point the sights at the target and fire.

Well, my point is that even then, dispersion harmed more than it helped.

With mistakes of that magnitude, about the only way to bring down someone is a straight six shot without any deflection at all.

However, in that situation, more dispersion just means fewer hits as all errors involved are of random nature.

The trembling hands of a panicked pilot would be enough to increase dispersion beyond what an ace might experience. However, this was a problem, not a solution.

>Perhaps one of the pernicious effects of modern combat sims - where people can practice for hours in a stress-free environment - is that they make people devalue just how very difficult it was for the vast majority of WW2 pilots to shoot anything down.

True :-) Deflection shooting can be mastered completely given enough practice. It's something the human brain was set up to do during millions of years of evolution.

>There is a very good reason why people don't go hunting birds on the wing with rifles - or even machine guns!

Well ... this reason is that shotguns have a very rapid rate of fire, firing hundreds of projectiles in an instant. If you'd slow that shotgun down to the rate of fire of the weapons you're comparing it to, it's quite doubtful that you'd still be happy about its high dispersion.

And shotguns have a terrible overkill capability, too - they kill with one shot, even if the vast majority of the projectiles misses. If birds were a lot thougher than they actually are, the shotgun would lose a lot of its appeal.

Because the difference between a shotgun and a machine gun is much bigger than it appears at first, the shotgun example really isn't that helpful.

Regards,

Henning (HoHun)

[Tony Williams]

All I can say, Henning, is that during WW2 the RAF disagreed with you - their studies with the Hispano showed that some dispersion of fire would increase the hit probability.

Tony Williams: Military gun and ammunition website and Discussion forum

[MANDO]

Originally posted by Tony Williams
some dispersion of fire would increase the hit probability.

At the same time it will decrease the chances of concentrating the fire on one spot.

[HoHun]

Hi Tony,

>All I can say, Henning, is that during WW2 the RAF disagreed with you - their studies with the Hispano showed that some dispersion of fire would increase the hit probability.

Well, that statement doesn't qualify the exact conditions, so it's not very useful. It certainly seems to be overly pessimistic about the pilots' deflection shooting abilities.

The Luftwaffe used the low-dispersion, low-velocity MG FF/M with good effect, and I'm not aware of any complaints about this battery. By the RAF approach, you'd have thought that the low velocity should make deflection shooting even more impossible than with RAF guns, and the low dispersion prevented any stray hits on a target that's far away from the pilot's faulty aiming point.

To me, this sounds a lot like the RAF had exceptionally poor standards in aerial gunnery training, as other air forces besides the Luftwaffe had good confidence in the effectiveness of aimed fire, too. The US Navy thrived on deflection shooting, using it as one of their means of breaking the Zero's superiority in the Pacific. I seem to remember reading that the Polish squadrons in the RAF outperformed their hosts in gunnery accuracy, too, which would be an indication of a training deficiency on part of the RAF.

(Just to make sure - the Mölders/Galland debate was about firepower, not about accuracy. The MG151/20 in an engine mount had just the same low dispersion as the wing-mounted MG FF/M. And fuselage-mounting, which yielded low dispersion figures, was considered "ballistically ideal" by the Luftwaffe.)

Regards,

Henning (HoHun)

[Tony Williams]

I believe you are right that RAF gunnery training was poor - it was that realisation which led to the introduction of the gyro gunsight, as I've said. However, I don't know that the training of other air forces was much better. Don't forget the German analysis that most successful attacks were at zero deflection, with 15 degrees being the maximum. I believe that the USA made a major effort to improve the realism of their training during the course of the war, but they still eagerly seized on the gyro gunsight.

When you think about it, realistic training in deflection shooting was actually very difficult until the advent of combat simulators. They could show pictures of deflection shots to indicate the aiming marks, but there were so many variables that that could only have given a general idea. Pilots could practice attacks using camera guns but there would be a long delay before the film could be analysed and used to help indicate problems and this would also be very resource-intensive, so I suspect that this wasn't used that much. It tended to be country boys with much shotgunning experience who did best.

TW

[HoHun]

Hi Tony,

>However, I don't know that the training of other air forces was much better.

At least the Luftwaffe und the US Navy devoted special attention to deflection shooting in their training.

Remember that the Luftwaffe went into the Battle of Britain with low-velocity, low-dispersion cannon - if their gunnery standards would have been as bad as you seem to believe the RAF's were, they would have found gunnery a lot more difficult than the RAF with their high-velocity, high-rate of fire, high-dispersion MGs.

However, I'm not aware of the Luftwaffe considering their gunnery performance lacking in any way. Even Galland, who voted for more guns on the Friedrich to make it easier for the average pilot to knock down enemy aircraft, intended to keep the low-velocity, low-dispersion MG FF/M cannon.

If deflection shooting was that dficult, and if dispersion was that important, things would have gone different in the Luftwaffe.

>Don't forget the German analysis that most successful attacks were at zero deflection, with 15 degrees being the maximum.

Well, without the details of that study, I'm afraid that doesn't allow any conclusion. Those zero deflection attacks are usually the result of the target failing to notice the attacker, and quite naturally, these are most successful by far.

>I believe that the USA made a major effort to improve the realism of their training during the course of the war, but they still eagerly seized on the gyro gunsight.

No doubt, the LCOS was a good thing. It's just that it's impossible to make assumptions about gunnery standards based on the fact of its introduction.

Regards,

Henning (HoHun)

[gripen]

Well, as noted above, the LW found out from gun camera analyses that an average LW pilot got just 2% hits when shooting on heavy bomber size target. The range is not specified but apparently this means all ranges, so 2% might be for something around 200 m, this means that at 500 m there would have been much less hits.

gripen

[HoHun]

Hi Tony,

>However, I don't know that the training of other air forces was much better. Don't forget the German analysis that most successful attacks were at zero deflection, with 15 degrees being the maximum.

This link to the Luftwaffe training booklet was already posted on another thread, but you might have missed it:

http://rafiger.de/Homepage/Pages/Schiessfibel.html

Page 14 re-inforces I point I've made in this thread: Dispersion doesn't help you. The Schießfibel:

"Accordingly [referring to example illustrations for faulty deflection shooting], don't rely on weapon dispersion - it won't help you if your aim is flawed! You can see here clearly how ACCURATELY you have to know and to apply deflection, or your fire will miss. But if you think now that you could simply adjust your MGs for a larger pattern to hit more reliably, then you're making a mistake. Your experience will be similar to that of the wild hunter in the picture on the right."

The latter advice is repeated on page 28:

"Another thing: Please don't invent new harmonization patterns, for example by adjusting the trajectory cross-over 100 m out etc. The ordered harmonization has been carefully devised by combat veterans and is good."

>It tended to be country boys with much shotgunning experience who did best.

Interestingly, Priller's book on the JG26 gives a breakdown of professions among the fighter pilots who served with JG26 and scored victories with JG26 or other units:

No/unknown pre-service profession: 126 pilots, 261 victories (average 2.1)
Career soldiers: 152 pilots, 1752 victories (average 11.5)
Pilots with pre-service profession: 166 pilots, 989 victories (average 6.0).

A detailed breakdown of the high scorers is available for III/JG26:

1 student (55 victories)
1 public servant (40)
2 merchants (64/27)
1 employee in public service (173)
2 technicians (71 each :-)
2 mechanics (24 each)
3 mechanics/precision instrument makers (63/52/40)
1 baker (48)
1 furrier (27)
1 optician (22)
1 carpenter (190)
1 musician (58)
1 metal worker/craftsman (89)
1 farm hand (20)

I assure you that it was Priller himself who put the single farm boy at the end of the list! :-) It was actually Erich Scheyda (who stated his profession as "coachman"), 188 combat sorties, 20 victories (32 points), KIA 25 years old.

Of the 166 pilots with a pre-service profession, craftsmen were the largets group with 90 pilots, the largest group of them being mechanics/fitters (25). It appears that a fair proportion of the latter were former ground crewmen who volunteered for pilot training.

If anything is striking about the list, it's - ironically! - the absence of farm boys. I think this might be systematic as men with agricultural professions might have been exempted from the draft to a certain degree in order to secure Germany's food supply. (Germany hadn't forgotten the food shortages in WW1, and Hitler really feared a revolution like it occurred at the end of WW1.) A contributing factor might be that a good education helps you to become a successful pilot, and farm boys might have been a disadvantage there.

Another irony about this topic is that due to the German laws gouverning hunting, it had become much more difficult for "ordinary" people to participate in hunting activities. It's ironic because this was a direct result of Hermann Göring's own hunting passion, and by devising the laws to keep hunting elitary, he was actually sabotaging the gunnery training of potential fighter pilot aspirants :-)

Among Göring's many titles was that of "Reichsjägermeister", and for once "Jäger" meant "hunter" literally instead of the "fighter pilot" we've gotten used to :-)

Regards,

Henning (HoHun)

[moot]

The public service employee and carpenter scored 173 and 190 resp.?

[HoHun]

Hi Moot,

>The public service employee and carpenter scored 173 and 190 resp.?

"Behördenangestellter" resp. "Schreiner", with 173 resp. 190 victories according to "J.G. 26 - Geschichte eines Jagdgeschwaders" by Josef Priller.

Regards,

Henning (HoHun)