Aircraft gun article

[Knegel]

Originally posted by Tony Williams
I am no statistician and don't want to get involved in complex mathematical arguments. However, it seems to me from what I can understand of some of the more abstruse posts that there it might be worth clarifying a couple of points in plain language, specifically, the difference between hit probability and kill probability.

The hit probability is simply the chance that the target will be hit - somewhere. It can be expressed as the hit probability per round, or per gun for a burst of fire of a given length, or for a burst of fire from a plane's entire armament.

The kill probability can be expressed as the chance that the target will be destroyed; either by a single round, or by a burst of fire as above. It incorporates the hit probability (because you're not going to kill something if you don't hit it) but multiplies that by the destructive power of each hit.

So to give a simple example, if one plane armed with many MGs has a hit probability for its entire armament (in a one-second burst, say) five times higher than that of another plane firing cannon, but that each cannon hit is five times as destructive as a bullet hit, then the kill probability of both armaments is equal.

Now let's turn to the argument that if an MG bullet kills the pilot, its kill probability is equal to that of a cannon shell (because you can't kill someone any deader). The validity of that depends on the probability that the MG bullet will in fact hit a vital point. This itself depends on two factors: the area of the vital point as a percentage of the area of the aircraft exposed to fire, and the probability of a bullet getting through the aircraft's structure and armour to hit that vital point.

I have a paper from RAF studies of the Bf 109F, in which they carried out some practice firings with different weapons which showed that in a rear attack the chance of a hit with a .50 AP bullet in the area of the pilot or vital controls being effective was 3%. That should not be too surprising in that passing through aircraft structures tended to destabilise the bullets, either deflecting them away from the vital point or tumbling them so they hit the armour side-on rather than point first.

Tony Williams: Military gun and ammunition website and discussion forum

Hi Tony,

i agree absolutly to all you wrote(well written!)!!  

Do you also have a test similar to that of the Bf109F to a unprotected target without selfsealing tanks?? Include this test the tank area?
On what distance this test was made?

Wouldnt the probability to hit a critical area increase much if there isnt plating and selfsealing tanks?? Wouldnt the resulting  higher killprobability, of this guns, increase much more than the killprobability of a 20mm, which have much less trouble with selfsealing tanks and plating anyway?


Hi HoHun,

if you did read what i wrote, why you dont saw that i did took the higher catrige power of the 20mm into account??

After Tony Williams statement regarding the term "hitprobability",  there is not much sence in many of your replys. I dont say that the formulas are wrong, but at the end my initial statement of the higher hitprobability of the .50cal armament was not wrong.

Can you please point me to the point in the 'Gesetz der großen Zahlen' where they refer to Nh??

As far as i know, any value that i multiply with a probability (P ) result in a new probability, therfor the value would be P(Nh), what would be the same like P(gun) or P(armament).

We can use Nh( a exact known value) and divide it by the ROF*Tf to use the resultig hitquote as bullet hitprobability, to estimate comming results under similar circumstances. But we cant use a unexact value, a probability, multiply it with a exact value to get a exact value Nh(number of hits) as result.  It remain a probability.

If the law of probability use a simplyfication, cause it dont matter for the calculation, it dont mean its a correct describtion!


Hi gripen,

maybe i dont understand the theory like it is written, or maybe i dont talk in the common therms so you have problems to follow my thoughts, but strangewise my conclusions are the same like the germans had(at least according to the book).
And looks like the Ing´s in the USA thought the same.

"Note that it is claimed in the book that against the fighters parameters would be different (favoring the ROF and somewhat lower calibres)."

If they was right to favoring the ROF and somewhat lower calibres, while shooting to fighters, this must be more important while shooting to unprotected fighters.

Nothing more and nothing less i told in my 1st post, till the end!

ROF and the target itself are important parts while determining  the killprobability.

btw, i never told that the .50cal is more powerfull than the 20mm´s in general!  I only disagree to the 5:1 Killprobability relation (same number of rounds hit) while shooting to smal targets in general and specialy unprotected targest!

Greetings, Knegel

[Karnak]

Knegel,

It sounds to me like you are overfocused on the unprotected pre and early war Japanese designs as the primary American targets.  While the Ki-43 and A6M never had really significant protection, later Japanese fighters such as the Ki-44, Ki-61, Ki-84, J2M and N1K did have protection.  The same is true for their bombers and attack aircraft.  The notorious G4M "One Shot Lighter" traded much range for protection in the G4M3 model.  The Ki-67 and H8K2 also had significant levels of pretection.

And that ignores the large number of well protected German aircraft they faced completely out of the picture.

[HoHun]

Hi HoHun,

>if you did read what i wrote, why you dont saw that i did took the higher catrige power of the 20mm into account??

I read your handwaving arguments and told you that you broke the logical chain. I pieced together the logical chain for you and posted the appropriate formula for your use. Go and use it.

>After Tony Williams statement regarding the term "hitprobability",  there is not much sence in many of your replys.

I knew Tony would be misunderstood. Each probability is the probability for a defined event happening under defined circumstances. Tony quoted the requirement for stating the burst length, for example. "Hit probability" without any qualifier is just that, the probability for one hit in one shot.

>I dont say that the formulas are wrong, but at the end my initial statement of the higher hitprobability of the .50cal armament was not wrong.

You stated:

"the .50 cal was the better weapon for the US need, cause, while the gun was good enough to destroy all japanese planes rather fast and to keep the german fighters away from the Bombers, it did provide a much better hitprobability than the relative slow firing Hispano."

This sentence fulfills none of the requirements for stating a complex probability (which could safely be called "hit probability" in inaccurate slang if all defining elements were stated), but you compared one weapon against another weapon. The only valid interpretation of that sentence is that you suggest that for each bullet, the Browning has a greater hit probablity than the Hispano, which - as I was able to conclude from the context - probably was not what you meant.

In short, you were wrong.

>Can you please point me to the point in the 'Gesetz der großen Zahlen' where they refer to Nh??

I already told you that I am not your teacher, and your question is of a rethoric and thus insulting nature as it's obvious that the law of great numbers is so general that it doesn't need to refer to WW2 gunnery directly to apply to it.

One more offense like that, and I'll put you on my ignore list.

Kind regards,

Henning (HoHun)

[BlauK]

Gripen,
I was pretty much agreeing with you an dsimply trying to direct HoHun to look at what you wrote... since he seems to believe you better that he believes others.

HoHun,
Knegel wrote about fast firing and slow firing guns in what you quoted. You simply cut away the RoF from the equation yourself when you believe it talks about both of those guns firing only a single bullet.
Keep the time as a factor in the equation and you will have the amount of bullets there as well. Without time there is no talk of fast or slow RoF.

"I already told you that I am not your teacher, and your question is of a rethoric and thus insulting nature as it's obvious that the law of great numbers is so general that it doesn't need to refer to WW2 gunnery directly to apply to it.

One more offense like that, and I'll put you on my ignore list. "

I was very tempted to comment on this... but, well.. it's not worth it

[HoHun]

Hi Blauk,

>Knegel wrote about fast firing and slow firing guns in what you quoted. You simply cut away the RoF from the equation yourself when you believe it talks about both of those guns firing only a single bullet.

As I stated above, I was aware what Knegel meant to say. Unfortunately, it was not what he had said - which is what I have quoted verbatim above - so I pointed out the confusion in terms.

>I was very tempted to comment on this... but, well.. it's not worth it

My ignore list is a simple tool that helps me not to waste time on people who have nothing to contribute. Consider yourself added to the list.

Kind regards,

Henning (HoHun)

[Knegel]

Hi HoHun,

it looks to me you mix up math with logic!!

We also can put logic into words, but of course this need the will and skill to read and understand the words. I have to admid that my skill in reading fomulas is not the best, but as BK´s example point out, your skill to read and understand words isnt the best eighter.

Maybe it wasnt as clear in the sentence you did quote, but the whole contex make it pretty clear:".........it did provide a much better hitprobability than the relative slow firing Hispano....... specialy if the smaler gun provide a much higher hitprobability."

I clearly talk about the different in ROF  and the gun and its hitprobability. If i talk about a MG, why shal i talk about a single shot???  Yes sure, now you will come and say, no you dont told that both shoot a burst of fire of a given length, but realy, do i need to say that the sun dazzles??  

I explained several times exact the same, but you always didnt agree!!
Example: "......if you agree that a shotgun provide a higher hitprobability, while shooting to a smal fast moving target, than a normal rifle, you also must agree that a MG, which shoot 12 rps have a higher hitprobability than a rifle.
And of course also 6 x 13rps(78 rps) provide a higher hitprobability, while shooting to this smal target, than 4 x 10rps(40 rps)."

Your answer:

">if you agree that a shotgun provide a higher hitprobability ...

The point is, I don't."

lol i just saw this in your last reply:
">Knegel wrote about fast firing and slow firing guns in what you quoted. You simply cut away the RoF from the equation yourself when you believe it talks about both of those guns firing only a single bullet."

BK dont believe i talk about the guns only shoot one round, thats the point you dont get. I didnt talk about the guns only shot one round, i was talking about the gun hitprobability!!   You remeber?? Hitprobability(bullet) * ROF = Gun hitprobability.  Since ROF implement rounds per sec, we have a clear determined timespan and number of rounds. Or will you tell me the Gunpower on Thonys page also is a wrong term?  

Of course if you only relay on your formulas, without to see other possibilitys of defination, you will get problems to understand someone who dont know the exact terms you use.
And if you only refer to pages, where someone who dont know many of the displayed sighns cant find a correlation to your examples, noone will be able to understand you, if he dont understand you already before!!
As i told, i dont would expect from someone to learn a new language just in a discussion, while iam able to talk in the known language.

And if you refuse to point more exact to what you refer to, how shal i understand?

"One more offense like that, and I'll put you on my ignore list."

Is a question, where you dont be willing to answer and offence for you??
Or are you not able to answer?

From my point of view your way to discuss is pretty much a offence. Looks like you dont be able to jump over your shaddow and to agree that my 1st statement wasnt wrong, though not good formulated from your knowledge of terms.

I many times told that iam not used to your terms, but you simply didnt care and go on to tell me that i dont understand this, but now i would say its the other way around.
You know many formulas and how the theory work in some special situation, but it looks to me you dont be able to implement it into a different contex, into the real world.  

I think this is enough, you also can set me onto your ignore list(you realy seems to think you be very important, if you threat with this), for now i dont got any new information out of your formulas.  The only new information i got is that the 'possibility theory' seems to use some simplyfied terms.


Karnak,

as far as i know the Ki43 and A6M was the main japanese fighter even in 1945.
When newer fighters came in more big numbers, the numerical and skill advantage of the US fighters(pilots) already was much to high.
All statements i found regarding the Ki44 was like this: Lack of fuel and crew protection; very vulnerable. The main version of the Ki61 was armned with 4 x .50cal and had roughly the performence of the Bf109F2 and that in 1943-45, who realy need to fear this planes anyway in a F6F, F4U, P51D or P38J/L??
Most other japanese planes was also smal, without effective tailgunners and not nearly as good protected like many other allied and axis planes.

Many times i told that this thought specialy count for the in general light protected japanese planes, and that while a escortmission the time to shoot and hitprobability was a not a unimportant factor( to bring the interceptor off the target),  but if you look to the result in war, you clearly can see that the 6 - 8 x .50cal armaments was pretty successfull, even vs the german fighters(even the P51B was successfull).
The brits did use only two hispanos in their Spits, this cannon hitprobability is even smaler than the 4 x 20mm of the F4U-1C, whould the P51 also have had only 2 x 20mm with 120 rounds(12 sec to shoot) + 2 x 50cal to keep the flight performence high??  Is there any hint that the Brits had a higher kill quote than the US boy´s?? Didnt the brits shot down well protected 109E´s and 110C´s without many problems with their poor 8 x .30cal??
The question remain: How many armament power is needed to bring a fighter down in a time and on a distance that the pilot would call satisfying and is a bit more satisfying worth to give up much of the time to shoot.

My assumtion is and was: If the pilot follow the instruction and go very close to shoot, it dont matter if he carry 6 x .50cal or 4 x 20mm while attacking a fighter, cause both armaments are able to cause deadly damages if the hitprobability is high.  When the hitprobability go down, much of the damagepower advantage get lost by the more bad armament hitprobability.  

To prove me wrong, you need to prove that the US armament was insufficient for their need.

Most of you realy sounds like the US pilots had real problems to shoot a enemy figher down, just like the brits while BoB vs the Bombers.

I realy start to wonder how the Ki43, Ki61 and Machi pilots was able to shoot something down at all.


Greetings, Knegel

[HoHun]

Hi Knegel,

>>"One more offense like that, and I'll put you on my ignore list."

>Is a question, where you dont be willing to answer and offence for you??
Or are you not able to answer?

Oh, I would have tried to answer a genuine, polite question.

As somehow, your questions regularly miss this mark, I'll just add you to my ignore list now.

Kind regards,

Henning (HoHun)

[BlauK]

Happy ignorance HoHun Enjoy it!

eh.. so that privileged contributors is his ignore list???? Doesn't that term actually mean the opposite

[Tony Williams]

Originally posted by Knegel
Hi Tony,

i agree absolutly to all you wrote(well written!)!!  

Do you also have a test similar to that of the Bf109F to a unprotected target without selfsealing tanks?? Include this test the tank area?
On what distance this test was made?

[/B]
Yes, the British assessed that a hit in the fuel tank area by a .50 stood a 10% chance of being effective if the tank was self-sealing, 40% if it wasn't.

Wouldnt the probability to hit a critical area increase much if there isnt plating and selfsealing tanks?? Wouldnt the resulting  higher killprobability, of this guns, increase much more than the killprobability of a 20mm, which have much less trouble with selfsealing tanks and plating anyway?

The probability of a hit wouldn't change, but the probability of a kill would. Yes, it was the toughening-up of aircraft (not just in terms of armour and self-sealing tanks, but also in the strength of their structure) which drove the development of more powerful guns.

The RAF's 8x.303 armament was fine against unprotected aircraft, right at the start of the war, but they soon found it increasingly difficult to score kills because the aircraft toughened up in ways which were not always recorded, e.g. armour added to existing aircraft during the BoB.

As I've said, the USAAF's preference for the .50 was the right military decision at the time, because it did an adequate job and the targets it was firing at were generally not as tough as other air-forces faced. And that decision brought lots of production, logistical, maintenance and training benefits.

Incidentally, I should perhaps clarify a couple of points from my previous post, which should be obvious, but (for the record):

First, that a very important factor affecting the hit probability is of course the nature of the target: its size, the firing range, whether it is flying steadily or manoeuvring.

Second, that the kill probability will be affected by the toughness of the target.

My post assumed that these variables would be constant for comparison purposes. To try to allow for them would dramatically multiply the complexity of the calculations.

Tony Williams: Military gun and ammunition website and discussion forum

[Knegel]

Hi Thony,

Originally posted by Tony Williams

Yes, the British assessed that a hit in the fuel tank area by a .50 stood a 10% chance of being effective if the tank was self-sealing, 40% if it wasn't.

 
The probability of a hit wouldn't change, but the probability of a kill would. Yes, it was the toughening-up of aircraft (not just in terms of armour and self-sealing tanks, but also in the strength of their structure) which drove the development of more powerful guns.

[/B]

Yes, regarding the hitprobability of the tanks, if there is no plating around,  of course you be right, the hitprobability dont change.
In this case i was more thinking of the 3% probability to hit  the pilot or vital controls or a Bf109F.
Without plating the probability to hit  the pilot or vital controls should increase much.

My thought is that while calculating(i like the term estimating more) the killprobability of a special armament, we need to take the different hitprobability of this armament into account, same like the different probabilitys of kill, while hitting the tankarea and structural area and the different hitprobability and resulting probability of kill, while shooting to different good protected pilots or vital controls into account. (crappy sentence, i know )

My estimation is: Many smal guns, which provide a high armament RoF, can be same effective vs smal unprotected targets, like a armament of cannons, which provide a much smaler armament RoF.
As more though the plane and the tanks get and as better the vital areas get protected, as less the high ROF count, simply due to the extreme decreasing killprobability of the smal bullet, while the 20mm damagepower result in a more constant killprobability on a wider range of 'plane toughness'.

Originally posted by Tony Williams

The RAF's 8x.303 armament was fine against unprotected aircraft, right at the start of the war, but they soon found it increasingly difficult to score kills because the aircraft toughened up in ways which were not always recorded, e.g. armour added to existing aircraft during the BoB.

As I've said, the USAAF's preference for the .50 was the right military decision at the time, because it did an adequate job and the targets it was firing at were generally not as tough as other air-forces faced. And that decision brought lots of production, logistical, maintenance and training benefits.

Incidentally, I should perhaps clarify a couple of points from my previous post, which should be obvious, but (for the record):

First, that a very important factor affecting the hit probability is of course the nature of the target: its size, the firing range, whether it is flying steadily or manoeuvring.

Second, that the kill probability will be affected by the toughness of the target.

My post assumed that these variables would be constant for comparison purposes. To try to allow for them would dramatically multiply the complexity of the calculations.

Tony Williams: Military gun and ammunition website and discussion forum [/B]

I absolutly understand why the variables are constant for comparison!

But i think you should point more to this not linear Killprobability of different damagepowers, while shooting to different sized, different tough and/or protected targets. Specialy the killprobability per amoload is not unimportant in this contex.  

Otherwise many more people start to calculate incredible cannon killprobabilitys and think the US engeeners was absolutly stupid not to use cannons. Same like others could calculate that 12 x .30cal had a higher damagepower than a 1 x MG151/20 and so a higher killprobability vs a IL-2.


Greetings, Knegel

[Tony Williams]

Any fighter armament fit was of course a compromise - within quite tight weight limits - between the volume of fire and the destructiveness of the projectiles.

At one extreme, you got up to 12 RCMGs pumping out a phenomenal volume of fire (over 14,000 rpm), which soon proved to be sub-optimal because the projectiles were insufficiently destructive. At the other extreme there were a few German fighters mounting a 50mm cannon, which was massively destructive but had great difficulty in hitting anything.

In practice, the calibre range which proved useful in WW2 was 12.7-30mm. Obviously, the 12.7mm armament was at its best against weak targets, whereas the 30mm were needed against the strongest targets. A decent (i.e. not low-velocity) 20mm cannon fit was, I believe, the best all-round compromise in WW2.

It is obvious that everyone except the USAAF agreed with this at the time, because all other air forces moved to 20mm (and even the USN wanted to, were it not for the reliability problems they experienced). In a way, the USAAF was lucky because the .50 proved well suited to their particular needs. If they had had tougher opponents to deal with, they would have been in a right mess.

Tony Williams: Military gun and ammunition website and discussion forum

[HoHun]

Hi Tony,

>A decent (i.e. not low-velocity) 20mm cannon fit was, I believe, the best all-round compromise in WW2.

>It is obvious that everyone except the USAAF agreed with this at the time, because all other air forces moved to 20mm

A modern cannon was the best all-round compromise, and the state of the art advanced as the war progressed. At the end of the war, the Luftwaffe considered the 30 mm cannon the best compromise and the 20 mm a secondary weapon like the cowl guns had been secondary to the 20 mm cannon before.

>As I've said, the USAAF's preference for the .50 was the right military decision at the time, because it did an adequate job and the targets it was firing at were generally not as tough as other air-forces faced.

If you had asked any fighter pilot who had to go up against the manoeuvrable Japanese or fast-climbing German fighters in a F4F or P-40 whether it would have helped him to save 400 lbs by installation of a cannon battery of equal firepower, there can be no doubt what his answer would have been. (For a P-40E, a 400 lbs weight decrease would have resulted in a 10% climb rate increase, for example.)

You only rate the 12.7 mm machine gun from an armament point of view, and it might be adequate from that perspective. However, from an aviation point of view, not getting rid of those 400 lbs of ballast was a bad decision, and there can be no doubt that American aviators paid for that. In a way, every US pilot who just couldn't pull tightly enough to evade that lethal burst of fire was killed by his own machine guns! With 400 lbs less weight, his turn could have been just the decisive little bit tighter.

That's the reason why the US decision in favour of the 12.7 mm machine gun, if it was a decision at all, was clearly wrong.

Regards,

Henning (HoHun)

[Squire]

Thats assuming you replace 6 x 50s with only 2 x 20mm: as was the case with the F4U-1C and A-36, in all likelyhood, the US probably would have gone to 4 x 20mm as a battery in their fighters. The weight difference would have been negligable. The F4F, F6F, F4U, P-51, P-40, P-47 all more than likely would have carried 4 x 20mm with @ 200 rpg.

The 400 lbs of weight is speculation at best. Who knows what Grumman or Curtiss would have gone with, we will never know.

Also, there seems to be a tendancy for people to debate these issues as if they just "waved a magic wand" < and a different armament comes along like presto. There are many reasons why countries go to war with the guns they do. The USA was not happy with the early 20mm Hispano, so they went with the .50 caliber, they couldnt wait around, there was a war on.

Btw, its interesting to note that the axis did not go to an all 20mm force in most of their fighters, Fw190, Bf109, Ki-84, Ki-61, Ki-44, A6M (later), MC series, all employed either 12.7 or 13.1mm weapons. So they obviously thought they were good for something, and not just "useless weight". The Soviets used 12.7s on many fighters as well.

...All that being said, I think the 20mm is the better weapon, and had the USA been able to get the problems sorted out sooner, would have been preferable I think to the .50 cal, but as it was the .50 gave very good service, and was widely liked by most that used it, from what I read.

[HoHun]

Hi Squire,

>Thats assuming you replace 6 x 50s with only 2 x 20mm: as was the case with the F4U-1C, in all likelyhood, the US probably would have gone to 4 x 20mm as a battery in their fighters.

If they had appreciated the weight problem in the first case, they might well have used the 2 x 20 mm option, especially with the early model fighters that were not so powerful.

>Also the F4F and P-40 would not have become uber fighters with the 400 lbs your talking about, and neither was ever employed as a "dogfighter" especially in the Pacific. They wouldnt be stall turning Zeros because they were armed with 20mm cannon. Thats grossly over stating it I think.

You are right, but I didn't claim that anyway :-) However, weight (or more accurately: mass) is a major factor for almost every aspect of performance, and there should be no doubt that the early US fighters were at a serious disadvantage there and would have greatly benefitted from a 400 lbs reduction.

And 400 lbs less with no disadvantage at all, that's something an airframe designer must work long and hard for. Just think of the P-40N or the FM-2 that actually had machine guns removed to save weight. For comparison: The gondola cannon of the Me 109 that reportedly turned the plane from a nimble interceptor into an unmanoeuvrable battleship weighed 474 lbs. Not that I consider the cliché justified, but 400 lbs more or less will affect the performance of a fighter.

>Also, there seems to be a tendancy for people to debate these issues as if they just "waved a magic wand" < and a different armament comes along like presto.

True enough. Engines and guns often require years of development time. However, in the case of the US Hispano copy, the British original had already reached a level of satisfactory reliability, so it seems not unreasonable to assume that a more determined effort would have resulted in a reliable US copy realtively quickly.

>Btw, its interesting to note that the axis did not go to an all 20mm force in most of their fighters, Fw190, Bf109, Ki-84, Ki-61, Ki-44, A6M (later), MC series, all employed either 12.7 or 13.1mm weapons. So they obviously thought they were good for something, and not just "useless weight".

Well, no simple answer to that. The Ki-44 was in fact an all-machine gun fighter, it appears no evidence of 20 mm armed versions could be found. (Of course, there was the caseless cannon, in a few examples.) In the A6M and the early Me 109, the MG had the advantage of a higher muzzle velocity and than the cannon and the advantage of a ballistally favourable centre-line position, too. In the late Me 109 types and in many of the Soviet fighters, only one cannon was carried so that the firepower increase was noticable. (The MG131 was a particularly light "heavy" machine gun.) In the case of the Fw 190, the machine guns seem not to have been worth it, especially considering that they not only increased weight but also drag. They were eliminated in some of the Sturmböcke, but I'd say they could have been eliminated from all 4-cannon Focke-Wulfs without anyone noticing. Of course, there is a school of thought that considers machine guns useful for sending a few tracers at the target to check aim, and then cut in with the cannon. This works well in simulation games, but I'm not sure it would work in real life, too.

>...All that being said, I think the 20mm is the better weapon, and had the USA been able to get the problems sorted out sooner, would have been preferable I think to the .50 cal, but as it was the .50 gave very good service, and was widely liked by most that used it, from what I read.

Well, I'm not sure contemporary literature has fully understood the disadvantages of the 12.7 mm machine gun. I have a dozen books here on my shelf that bash the Messerschmitt gondolas for their 500 lbs weight penalty, but somehow, there's not one book that bashes the US batteries for being 400 lbs overweight. I don't think the Messerschmitt gondolas were quite as bad as my books would have them, but I don't believe the extra 400 lbs of the US batteries were a non-issue either.

Regards,

Henning (HoHun)

[Knegel]

Hi,

"A modern cannon was the best all-round compromise, and the state of the art advanced as the war progressed. At the end of the war, the Luftwaffe considered the 30 mm cannon the best compromise and the 20 mm a secondary weapon like the cowl guns had been secondary to the 20 mm cannon before."

Looks like he still cant see the different need while fighting B17´s, B24´s, IL-2´s, P47´s, La(GG)´s, Wellingtons, Mosquitos, Lancasters and other very tought planes, in oposide to  the FW190A as most though oponent in big numbers, while the biggest number of enemys was Ki43´s, A6M´s, Me109´s and other rather light protected and/or relative smal targets.

Even the FW190´s did fear the .50cals of the B17´s pretty much.

And it looks like he realy think a nation, which did pop out CV´s, many other ships, thousands of Bombers, fighter, tanks etc, one after the next, wouldnt have been able to introduce a 20mm in big numbers, if there would have been a real need.  They had the 20mm in the P38 very early, so they must have been able to produce it somehow, but no need = no motivation.

Btw, 2 x Hispano II(dont the US 20mm had a smaler ROF?) would have provided around a 4 times smaler armament-hitprobability  than the 6 x .50cal, without to consider the shorter time to shoot,  vs smal fighters this would have been a pretty bad handycap. 4 x 20mm would have been needed, but this would have increased the weight and reduced the ammo load, and wouldnt the long barrels also decrease the performence(afaik it did in the SpitVa to SpitVb, or was it the weight?)?

Anyway, at the end of the war the USA did introduce the new Gunsight, which did increase the killprobability much, specialy while a fightercombat. So the already good working armament got even more effective.


Greetings, Knegel