.50 cal machine guns vs 20 mm autocannons on US aircraft

[Shortround6]

The point is that the USN much preferred the four gun with more than 400 rounds per gun installation of the F4F3 over the six gun with 240 rounds of the F4F4 to the point that the late F4F4s switched back to the four guns as well as the FMs. The Hellcats and Corsairs carried the six guns with 400 rounds without much performance penalty. It is apparent that firing time was important to US pilots. Perhaps it did not matter as much to British and German pilots and the reason might have been that their AC could not stay in the air as long as the US models. Shorter duration flights don't need as long firing times. If you are going to be in the air for four hours or more it is nice to know that your ammo supply may be adequate. A fighter with empty guns is useless. If you read "The Shattered Sword" the Zekes having to land continually to replenish the 20 mms during the attacks from the AC based on Midway had a major impact on the eventual outcome of the battle. I have read that in the Pacific some Corsair pilots would switch off two guns until the other four ran out in order to stretch out firing times. Does not seem logical to me to simply ignore the huge difference in firing times for the P51 with 20mms and the F4F3 with four fifties.

A .50 cal with 400 rounds weighs about what 20mm Hispano does with 120 round (mounts, cocking units, heaters and such can throw this off) for a plane that can carry only the weight of four .50s with 400rpg each maybe it does make sense to go for the longer firing time. When you go to Six .50s with 400 rounds each vs four 20mm Hispanos and use the FULL weight of the .50 cal guns and ammo then the firing time differences could drop to only 20-25% greater. With the Navy figuring that one 20mm was equal to three .50 cal guns the four 20mms have a target effect of twelve .50cal guns. They may not need as long a burst per target and equal up some of the firing time that way.


As far as the Zeros go, the early Japanese drum fed 20mm cannon actually weighed less (3-6kg) than the American .50 cal Browning (or the later Japanese navy 13.2mm copy) and the weight of the ammo was such that 60 rounds of early Japanese 20mm ammo weighed about as much as 105-110 round of .50 cal ammo. Granted the Japanese cannon used a heavy drum but how far would they have gotten at Midway defend their fleet using Zeros armed with a pair of 7.7 mm machine guns and a pair of 12.7/13.2mm Brownings with just 120 rounds (help make up for the drum) per gun? 9.2 seconds firing time vs the 7.5 seconds of the 20mm cannon.

 

[tomo pauk]

The Japanese 20mm was a copy of the Oerlikon with a short barrel to save weight and only had a 60 round magazine. But since the 20mm was their most effective weapon the Zekes had the IJN CVs were kept busy recovering, rearming and relaunching the Fighters to cope with the onslaught of the Midway based AC. Since the flight decks were being used the Japanese could not ready another strike to be launched. The Japanese attack planes had to get to the flight deck before the ordnance could be armed and the engines warmed up, unlike the US CVs with the open hangar decks. According to "The Shattered Sword" which seems to be the best and most recent version of the battle, that was the reason the US VSBs and VBs were able to enjoy such success. The small magazine capacity was the problem, not the gun itself or the ballistics. A Wildcat, SBD, Avenger or B26 with a Zeke on it's tail with only 30 cal mgs was very difficult to shoot down.

Yep, German MG FF IJN's Type 99-1 do show lineage from the Oerlikon's basic design.

It still stands that, not just for needs of IJN fighters, that drum-fed cannon was bad choice when one needs to fight a prolonged battle. It was of low MV, low RoF, widely spaced one from another (in SE fighters) - pilot must be a good shooter to make hits/kills. VVS was fielding belt-fed cannon prior WW2, LW's MG-151 (15mm) was introduced in early 1941, MG-151/20 from June 1941, RAF's Hispano was belt fed from about that time.
All those weapons were achieving better RoF and MV than Zero's cannons of Midway era, German Soviet gun were able to be synchronized, their ammo complement was not hampered by the drum size. Unlike what Zero had in wings for Midway.

 

[Denniss]

AFAIR the 99-1 was a license-built Oerlikon FF F while the MG FF was an inproved FF F using a longer, more powerful cartridge. FF F had 20x72, MG FF 20x80 cartridges.
(From memory) the 99-2 was a license-built medium length Oerlikon FF L and the Hispano was a development (loosely) based on the long FF S.

 

[Shortround6]

I don't think I said this. What I said was "Does anyone have a report from the Germans or Japanese saying they were not concerned about the American fighters because they only had 50s?"

yes you did say .50 cal but I don't think you are going to find a such a statement about either caliber. Not concerned about getting hit is a while lot different than how fast a gun/ammo combination can wreck a plane or over come built in protection.

I don't understand this. Did you mean "doesn't mean the .30 cal gun is not a plane killer…}

Then you have a double negative. It was possible to bring down planes using .30 cal (7.7-8mm) guns but few people viewed them as "plane killers" like the heavier guns.

I don't understand why you keep saying this. I haven't seen anyone say it was a super weapon or a "be all and end all of aircraft armament".

I keep saying because many people keep saying the .50 must have been good because the US won the war with it (and kept it to Korea) or that the US shoot down XXXXX planes using or try to say it could out range 20mm cannon or other nonsense.

It was adequate as an air weapon (ground may very well be different) and that is a different thing or category.

I don't understand this argument. During war time lots of money and time go into advancing the current capabilities. What other weapons system could you apply you philosophy that spending money and time on improving was a sign of lack of capability, engines like the Merlin, airframes like the Fw-190, bombs, tanks????

Countries spend money on weapons systems to keep ahead of the enemy and since it takes years to get form drawing board to the front lines research is usually going on. Unless the User is really happy with what they are using. How much effort did the US or England put into replacing the 105 howitzer or 25pdr during the war? Or how much effort did the US put into replacing the Grand, the BAR, the 1919 machine gun? The US didn't even put quite the priority on getting a replacement for (or even upgrading) the Sherman tank. And yet there were, by count, several dozen projects for faster firing .50s, higher velocity .50s ( a least one larger cartridge case and not just a hot load) , .60 caliber guns (several different receivers) using more than one cartridge case, and fast firing and/or higher velocity 20mm cannon( again with different cartridge cases). A number of these projects date from around 1942. The US may have pulled the German mistake by trying to jump further than the technology allowed as many of the High velocity projects had goals of 3500fps (1060mps).
If the .50 was so good why ALL the effort to replace it? and then the Air Force goes into Korea with a "tweaked" version of the old gun? Somebody may have been believing their own press releases.

For a brief rundown on the models programs try;
View: https://www.youtube.com/watch?v=-p8h43TRXwk

Certainly by the end of WW2, the M-2 armed fighters were not up to world standard. However, had the M-3 been incorporated they would have been. Indeed, the M-3 armed F-86 was as potent as the F9F and more so than the Mig-15. This all changed with the M-39 20 mm.

covered above.

Not adequate to do the job like there was a big demand to upgrade the F4F once the Zero was encountered.

There is a difference, in my opinion anyway, between what was decent armament in 1942 and what was decent armament in 1944. The .50s did the job, that doesn't make them great or ideal or even particularly desirable, it makes them adequate no more but no less. It also means that a number of American fighters had lower flight performance than they otherwise might have had if the US had had better guns or been a bit smarter in specifying ammo loads.

The M-14 seems well liked but out of place in the jungle as any full sized rifle would be. In the Middle East it seems to be popular.

It wasn't the size in the jungle, it was the requirement to fire full automatic. No 10lb weapon is controllable in full auto fire using a cartridge in the 7.62X51 power class. It was a dumb requirement, "solved" by removing the selector switch/lever.

It seems to have been around a long time for such a miserable failure.

Great airfield defense weapon, Great jungle/city close quarters gun. Not so good in the desert or mountains of Afghanistan, which is why the old M-14s are getting popular again. Too many high ranking people have too much invested in the M-16/M-4 at this point to admit it has been a limited use weapon from day one (that and every replacement, using the same cartridge, has been an even more expensive proposition)

 

[Tante Ju]

It wasn't the size in the jungle, it was the requirement to fire full automatic. No 10lb weapon is controllable in full auto fire using a cartridge in the 7.62X51 power class. It was a dumb requirement, "solved" by removing the selector switch/lever.

I agree, 7,62 mm rifle round is simply too powerful to be effective controll. I guess one more thing about M-14 was its unsuited ergonomics - it was a classic rifle shape, not even having a pistol grip to help control it.

 

[Glider]

Its digresing I know but when people say that the M14 was very popular, a lot of countries who spent their own money went for the FN instead of the M14. Countries that were equipped with the M14 tended to get them via MAP.

 

[tomo pauk]

Hi, David,
What could be a reasoning for Sabre's armament being as potent as Panther's, and more potent than MiG-15's?

 

[vanir]

The NS-37 fires unevenly and has sledgehammer recoil. It's not accurate (unless you're taking single shots at slow moving targets), but for shooting at bombers from fairly close range, in which case it'll take a whole engine right off it.

The 23mm guns are very good weapons though. Overall they're like a very sturdy 2cm aero gun, but the slight increase in calibre is worth almost twice the explosive fill. They're a good gun, reason they developed the fast firing twin-barrel versions in the same calibre that became 2nd-4th gen standard fitment. Being speculative here though, resident gun experts may correct me, I know little about them really.

I did read some good performance reports somewhere on those final versions of the BMG fitted to things like Sabrejets, they really pack a wallop. 6 guns at something like 1200rpm each, it's minigun territory.
Pilots didn't find them at all deficient. And until the vulcan no alternative really seemed to get full backing from all sides.

 

[gjs238]

Its digresing I know but when people say that the M14 was very popular, a lot of countries who spent their own money went for the FN instead of the M14. Countries that were equipped with the M14 tended to get them via MAP.

Who's to say a pistol grip stock couldn't be installed on an M14?

 

[Shortround6]

Before we go too far afield the point of bring up these infantry weapons was to point out that while US Ordnance did do some very good work they also made some very basic errors at times. It is one thing to try and push the boundaries in a research project, it is another thing to ignore the results of the research project/s ( and years of practical experience) and insist that certain features or performance levels be meet in production weapons.
When dealing with Full auto 10lb rifles firing full power ammunition it not just the shape of the stock it is physics. Unless you can repeal one or more of Newtons laws there is only going to be one outcome. You can't ignore it or wish it away no matter what rank in the army you have.

In reply to this question " Who's to say a pistol grip stock couldn't be installed on an M14?"

There was one, the M14A1 (you can google the image) plus it had a Bipod, still didn't work.

 

[Glider]

Who's to say a pistol grip stock couldn't be installed on an M14?

No one but dont think it would change the world

 

[tomo pauk]

The NS-37 fires unevenly and has sledgehammer recoil. It's not accurate (unless you're taking single shots at slow moving targets), but for shooting at bombers from fairly close range, in which case it'll take a whole engine right off it.

...

Perhaps you could point to a source that confirms that N-37 had those issues? Nothing bad is mentioned in Tony Williams' 'Rapid fire'.

 

[gjs238]

I agree, 7,62 mm rifle round is simply too powerful to be effective controll. I guess one more thing about M-14 was its unsuited ergonomics - it was a classic rifle shape, not even having a pistol grip to help control it.

I quoted the wrong post on my post.
I did not mean to suggest that the M-14 would be improved by the installation of a pistol grip stock.
I merely wanted to suggest that if one was wanted it probably could have been installed.

 

[davparlr]

I keep saying because many people keep saying the .50 must have been good because the US won the war with it (and kept it to Korea) or that the US shoot down XXXXX planes using or try to say it could out range 20mm cannon or other nonsense.

So, you are saying the decision makers in the Army and Navy were incompetent because they stuck with a weapon that was not good? This, of course is nonsense. They were well aware of the plusses and minuses of the various armament options and made their decision based on what they perceived as the best way to wage the war. Their conclusions were that the weapon systems they had were good and effective and any disruption in upgrading armament was not warranted by the increased performance of a new weapon system.

The WWII M2 50 cal was not great but it was good and, in fact, could be upgraded to the M3 and, when properly configured, be equitable in performance to the Korean 20mms in effectiveness.

Unless the User is really happy with what they are using. How much effort did the US or England put into replacing the 105 howitzer or 25pdr during the war? Or how much effort did the US put into replacing the Grand, the BAR, the 1919 machine gun?

Do you know?

The US didn't even put quite the priority on getting a replacement for (or even upgrading) the Sherman tank.

The Army must have spent loads of money developing replacements for the Sherman, the T-20, T-25, T-29, T-30, and eventually successful T-26.

View: https://www.youtube.com/watch?v=Jt5bJQOkI1g

And yet there were, by count, several dozen projects for faster firing .50s, higher velocity .50s ( a least one larger cartridge case and not just a hot load) , .60 caliber guns (several different receivers) using more than one cartridge case, and fast firing and/or higher velocity 20mm cannon( again with different cartridge cases). A number of these projects date from around 1942. The US may have pulled the German mistake by trying to jump further than the technology allowed as many of the High velocity projects had goals of 3500fps (1060mps). If the .50 was so good why ALL the effort to replace it?

Aircraft technology developed faster than just about all other technology in WWII. In four or five years it went from being barely out of biplanes, shooting twin .30s, to jet and rocket aircraft firing 20mm cannons and up, an incredible leap. All aspects of aircraft were developed intensively, engines, aerodynamics, avionics, survivability, etc., some of which were already deemed adequate. It is not surprising that armament, and the .50 machine gun, was left out of this upgrading expense effort.

and then the Air Force goes into Korea with a "tweaked" version of the old gun? Somebody may have been believing their own press releases.

Because it was not only adequate but was effective and when upgraded, the available 20mm offered little to no in improvement

For a brief rundown on the models programs try; Milsurps - The Machine Gun (by George M. Chinn)

This looks interesting. Thanks for the site. I am going to enjoy reading it.

That rather depends on how you rate the effectiveness of the .50 and 20mm Hispano. The Navy thought that one 20mm Hispano was worth three .50 cal guns so four Hispanos were worth 12 M-2 Brownings. Now if the 1200rpm M-3 Brownings are worth 1.5 times the M-2 that means the Saber had the equivalent of 9 M-2 Brownings, leaves it a little short of the 12 mark doesn't it?

Actually no, the projectiles hitting the target and the damage they do is what counts. If we look at an individual event, in this case a timed burst of fire e.g. one second, the important factors are probability of a strike, which is the probability of a strike per projectile calculated with the number of projectiles fired, and probability of damage given a strike, in this case the 20mm being three times more effective than the .50 cal
Here is a repeat of my post on another thread comparing the F-86 to the F9F in firepower, reformatted.

I did run a few simple probability calculations on probability of number of strikes given the probability of a strike for 47 r/sec (F9F) vs.125 r/sec (F-86). This is for a one second burst. Two 20mm rounds are used as a reference.

For 2% probability of a strike per projectile:
Out of 47 attempts, the F9F has a 24% probability of 2 or more 20 mm rounds hitting.
Out of 125 attempts, the F-86 will have 4 or more 50 cal rounds hitting (24%).
For 5% probability of a strike per projectile:
Out of 47 attempts the F9F has a 69% probability of 2 or more rounds hitting.
Out of 125 attempts, For slightly better probability, the F-86 will have 5 or more rounds hitting (75%).
For 10% probability of a strike per projectile:
Out of 47 attempts the F9F has a 96% probability of 2 or more rounds hitting.
Out of 125 attempts, the F-86 will have 7 rounds hitting (97%).

Obviously, the more round fired the higher the probability of hits. As shown here, for increasing probability of hits, the F-86 will deliver more hits, from 2x at 2% probability of a hit to 3.5x at 10%. As the planes get closer, or the pilot more accurate, or the aircraft more stable, etc, the advantage moves in the F-86's direction. As the planes move farther apart, the advantage moves to the 20mm. However, for any distance, the probability of equal hits always falls in favor to the F-86.
Given the Navy analysis of one 20mm equal three .50s, at about 5% probability of strike (five projectiles hitting out of one hundred), the F9F and F-86 are roughly equal in fire power, below 5% probability of strike, the F9F delivers more damage, above that, the F-86 is more effective, at least according to probability.

It also must be noted here that one poster pointed out that the armament of the F-86 is lighter than the F9F, although a couple of seconds less in firing time. Equal being equal, both are probably equal in weight per firepower. I did not check his numbers.

It is apparent to me that the six M-3 machine gun battery on the F-86 was reasonably equal in effectiveness and weight to the four M-2 cannon on the F9F, and for the Korean War, was as state-of-the art as the 20 mms, not just a "tweaked", old gun. I think the claim that the Korean War F-86 was under-gunned is a myth.

No I don't have any "real evidence" that would not have been devastatingly effective, but then do you have any "real evidence" that they would have been devastatingly effective, or is this supposition?

You are the one making the claim that they are not effective, so I think you are the one that should support it.

There is a difference, in my opinion anyway, between what was decent armament in 1942 and what was decent armament in 1944. The .50s did the job, that doesn't make them great or ideal or even particularly desirable, it makes them adequate no more but no less. It also means that a number of American fighters had lower flight performance than they otherwise might have had if the US had had better guns or been a bit smarter in specifying ammo loads.

They were adequate and effective.

It wasn't the size in the jungle, it was the requirement to fire full automatic. No 10lb weapon is controllable in full auto fire using a cartridge in the 7.62X51 power class. It was a dumb requirement, "solved" by removing the selector switch/lever.

In reality, I have no idea. I did talk to my brother, who was trained on M-14. He stated that there were some M-14s that retained their auto functions but in order to be issued one a soldier had to be auto-fire qualified. Now, I am as old as dirt and he is older than I am, so memory may be a problem. He was in the Army Security Agency when he was sent to Vietnam in early 1965. As the biggest dude in the group he was handed an M-60 and told he was the machine gunner. He thought the M-60 was a good weapon and did not hear any negative things about it. His favorite saying was that it "barked here and bit out their". Being in the ASA, he was not meant to be involved in any combat and, in fact, he had marines assigned to guard his facility, an air conditioned trailer, which made the marines jealous. The machine gun was strictly assigned for defensive purposes. He also was issued a 1911 colt, he said all machine gunners were.

 

[davparlr]

Hi, David,
What could be a reasoning for Sabre's armament being as potent as Panther's, and more potent than MiG-15's?

Hi, Tomo
See above post for probability analysis of the F-86 vs. F9F.

For the Mig-15, here is a repeat of my post on another thread modified a bit.

I wanted to comment on the perception of the effectiveness of the Mig armament compared to the F-86. In another thread, I did an analysis of the probabilities of effectiveness of the F-86, with six browning M3 50 cals compared to the F9F with four M2 20mm cannons. This indicated that the F-86 and F9F were roughly comparable in effectiveness at about 5% probability of a hit per round. Above that point, like 10% probability of a hit, the F-86 was increasing in effectiveness. This was based on the Navy's assertion that the 20 mm round was comparable to three 50 cal rounds.

I thought I would do a similar comparison with the F-86 and Mig-15. The Mig-15 has two 23mm NR-23 cannon firing a total of 27 rounds/sec* and one 37mm N-37 cannon firing 7 rounds/sec. To make this simple, I will assume these will have a one hit one kill capability and will treat both cannon types as the same. So, total round/sec of the Mig-15 is 34. At this rate, and with a probability 5% hit per round, the probability of one or more hits with a one second burst is 83%.

The F-86 has six Browning M3 machine gun capable of a total of 125 rounds/sec*. At this rate, and 5% probability of a hit per round, the F-86 will have 88% probability of four or more hits, or a bit better at getting four hits than the Mig has of having one hit. So, with these assumptions, the F-86 has a slight advantage in kill at a 5% probability of a hit.

At a 10% probability of a hit per round, the Mig will have 97% probability of one or more hits. The F-86 will have seven or more hits with a probability of 97%. So, at a 10% probability of a hit per projectile, the F-86 will strike a killing blow with a shorter burst than the Mig-15

Now I don't really know the comparison of 23 mm or 37 mm to the 50 cal and of course, the probability of one hit, one kill is not one, nor do we know how the effective distribution of over the aircraft. However, if one 20mm is equal to three 50s, it appears reasonable to me that one 23mm would be equal to four 50s. The 37mm is a ringer. It is noticeable that, as the probability of hits per round increases, the high rate of fire F-86 becomes more effective.

Additional notes would be that it is my understanding that the 50 cal has better ballistic characteristic than the 23 mm or 37mm (it certainly has better initial velocity) which could possible affect the critical probability of strike per round. Also, the F-86 with its radar ranging gun sight would also improve the probability of strike per round. Both of these statistically improve the advantages of the higher rate of fire weapons.

In general, in my opinion, the armament of the F-86 was equal to or better than the Mig-15. It is also interesting to note that the AF did not change to the 20mm until the much faster firing M39 (twice a fast as the M2 cannon) became available late in Korean War.

*I used the higher rate of fire of 1250 rounds/min vs.1200 r/m, and also the higher rate of fire for the 23mm of 800 r/m (AF test was at 650 according to Wiki)

 

[tomo pauk]

David, hit probability makes just a part of weapon's 'potency', the other part is effect (of a bullet/shell) upon the plane is hit.
For MiG-15, even at 600* rpm per 23mm gun, that makes 1200 rpg per plane, or 20 rps per plane. Mutiplied by 200g, that's 4 kg per second. For F-86, 120 rps per plane, multiplied by 46g per projectile, makes 5,52 kg. So Sabre fires greater mass from it's guns.
Now, how much a kg of cannon shell is worth of HMG bullets? Even if the ratio is 1,5 to 1, MiG-15 leads in effect on target. Then we add the 37mm (that one fires at same MV as 23mm, 690 m/s), 400 rpm -> 6,67 rps -> 4,9 kg per second.
So even if the Soviet cannons were firing ball ammo, they offer almost 9 kg per second of fire weight vs. Sabre's 5,52 kg. For same gun weight.

For Panther: 102g shell x 4 cannons x 11 rps = 4,49 kg per plane per second. Sabre throws 1/4 more mass, but Panther fires shells, not ball. Advantage Panther, that carries 200 kg of guns vs. 180 kg of Sabre.

While USAF was installing HMGs in their fighters, it's also true that USN was quick to adopt all-cannon weaponry for their fighters, for same post war era. Since it seem impossible that both were right, I'll bet to USN. Other AFs moved for cannons in the same era, making USAF the only proponent of HMGs of that time.

* Tony Williams ('Rapid fire' book) states that RoF ranges from 850 - 950 rpm

 

[Shortround6]

So, you are saying the decision makers in the Army and Navy were incompetent because they stuck with a weapon that was not good?

Yes and no, some of decisions were incompetent. the story of the US 20mm Hispano is a long and sad one. Some ordnance officials refused to change earlier decisions on details like chamber length ( a difference of 1/16 of an inch) no matter how many demonstrations showed it was wrong until guns were stacked in warehouses by the 10s of thousands with no takers because of the resulting poor reliability. In that case the decision to stick with the .50 rather than try to use defective 20mm guns was the right one. Bur it wasn't a question of sticking with a gun that was "good", it was a question of sticking with the lesser of two evils. a gun of adequate power and reliability (many early .50 cal installations weren't that good but that was the installation and not the basic gun) vs a harder hitting but much lower reliability gun, and again the lower reliablilty was pretty much the ordnance depts own doing, British guns (with the shorter chamber) being much more reliable than the American ones.

This, of course is nonsense. They were well aware of the plusses and minuses of the various armament options and made their decision based on what they perceived as the best way to wage the war. Their conclusions were that the weapon systems they had were good and effective and any disruption in upgrading armament was not warranted by the increased performance of a new weapon system.

They certainly spent a lot of time, money and energy on projects to "improve" their armament options. Unfortunately many of the performance goals were unrealistic which lead to less than really useful weapons. Incompetence? you judge, a number of projects involved the US .60 caliber cartridge. While using the same diameter projectile as the German 15mm round it used a much larger and more powerful cartridge case. This of course meant the gun firing it had to be larger and heavier than the German 15mm/151 and in fact the guns that used it were substantially heavier than the 20mm Hispano cannon. While it had perhaps a rather admirable short flight time and high armor penetration is was a bit lacking in HE content and barrel life would have been short. Deficiencies that should have been well known at the time. This cartridge case was later shortened and necked out to form the 2102mm round used in the Vulcan guns. I don't believe any other country pursued teh high velocity goal with the intensity the US did. They even tried necking down that .60cal case to .50 cal. Great velocity but the guns was the same size as the .60 (larger than the 20mm Hispano).
Again the decision makers had to use what the had, the .50 cal M2, because too many of the "project guns" failed to yield usable results.

The WWII M2 50 cal was not great but it was good and, in fact, could be upgraded to the M3 and, when properly configured, be equitable in performance to the Korean 20mms in effectiveness.

yes, (sort of) no and no. the M2 could not be turned into an M3, there were too many differences. the M3 had to be manufactured new, no upgrading or retrofitting of old receivers, and again no it did not equal the 20mm guns in Korea.

Do you know?

Neither country spent much time or effort improving those field guns. Any modifications were minor and no real replacements were tried until after Korea. Unless you know different? The US had few (if any official) projects to replace the M1 rifle, the BAR or the 1919 mg during the war. The Johnson guns were pre war.

The Army must have spent loads of money developing replacements for the Sherman, the T-20, T-25, T-29, T-30, and eventually successful T-26.

the T-29 and T-30 were completed post war. While the M-4 was a world class tank in 1941 (initial design) and 1942 and while ordnance tried the decision makers screwed this one up. Depending on you opponent NOT to upgrade his tanks for several more years is NOT smart. The decision to upgrade the Sherman (even if they didn't go for the M-26) should have been made sooner. Much like the Russians upgraded in the T-34 in early 1944.

Aircraft technology developed faster than just about all other technology in WWII. In four or five years it went from being barely out of biplanes, shooting twin .30s, to jet and rocket aircraft firing 20mm cannons and up, an incredible leap. All aspects of aircraft were developed intensively, engines, aerodynamics, avionics, survivability, etc., some of which were already deemed adequate. It is not surprising that armament, and the .50 machine gun, was left out of this upgrading expense effort.

Actually it almost defies belief that the armament should be left out of the upgrading. The primary purpose of a fighter plane is to get a an effective battery of guns into a firing position to shoot down an enemy aircraft. "engines, aerodynamics, avionics, survivability, etc" are all part of getting into the firing position. to leave out upgrading the armament is leaving your newer much improved fighters with a massive handicap in using old armament. The US is the ONLY major (one of the big 5) country to exit WW II using pretty much the same aircraft gun as it started with.

You are the one making the claim that they are not effective, so I think you are the one that should support it.

You forgot "devastatingly" . What is "devastatingly effective"? in order to prove or disprove it we have to know what it is. Number of projectiles per second, weight of projectiles per second, weight of explosive deliverable per second?

In reality, I have no idea. I did talk to my brother, who was trained on M-14........

The M-14 may have been to big and heavy for ideal jungle use, but that is a theater condition, while the uncontrollability is universal the world over. Not the just the M-14 but nobodies 10lb rifle firing the 7.62X51 was controllable in full auto. Dumb requirement.
The M60 was a mixed bag, it did some things right and got some things wrong and what was wrong was stupid stuff that shouldn't have been. One thing was that on early versions it was possible to assemble the gun with the gas piston in backwards, gun would fire one shot and stop. Can be gotten around by training (somewhat) by why not make the gun a little more soldier proof to begin with? another thing was that the barrel, gas cylinder and bi-pod came as a one piece unit. Carrying a spare barrel meant carrying a spare bi-pod. Now the bi-pod did give the gunner (or his assistant) something to hang onto while changing the barrel but it also meant the gun flopped on the ground when the bi-pod was removed. An asbestos glove was part of the barrel changing gear (according to the book). one cold over look such things on a WW I or 1920s machine gun. On a 1950s machine gun it leaves you wondering where the guys who approved it it were hiding for the last 20 years. An other feature )(not) was that the replaceable barrel had a fixed front sight. Bren guns had movable front sight sights. two or more barrels could be zeroed to the same point of impact using the same rear sight settings and the barrels swapped in combat with little or no change in impact with no work by the gunner. The M-60 required the gunner to know (or record in a pocket notebook) the rear sight settings for each barrel and change the zero setting on the sight each time the barrel was changed. Again,not a good feature on a a 1950s gun. There are a few other details that were less than world class.
All in all if leaves one less than impressed with some of the personnel in the ordnance dept. others may have done a very good job on other projects but US Ordnance was certainly far from infallible at times.

 

[vanir]

Perhaps you could point to a source that confirms that N-37 had those issues? Nothing bad is mentioned in Tony Williams' 'Rapid fire'.

The VVS. TsAGI has something written up about it, the IL2 (game) designers mention it. The NS-45 was much worse, unsuccessful really. Just too powerful. But the two service evaluation flights of the Yak-9T with the NS-37, one I think at Leningrad Front, the other in Ukraine they wound up spending most of their time taking pot shots at German fighters at extreme range. They cited that it shook the aircraft violently. The MiG-9 had issues with it too. Gases entering the engine intake but also it shook the aircraft violently. The MiG-15 had a great big muzzle brake on it but seriously, how much is that going to help in an aircraft of that weight?

You know the ballistics on that Nudelman are like a BK 3.7 right?

 

[tomo pauk]

The NS-37 and N-37 were two different guns using two distinctively different rounds.
The WW2 era NS-37 was indeed as powerful as Bk 3,7, but N-37 was somewhat more powerful than Aircobras M4 gun. The NS-37 was firing a 735g shell at 900 m/s, N-37 same weigh at 690 ms - muzzle energy for the MiG-15's big cannon was some 2/3rds of Yak-9T's.
Hence, we should discard what IL-2 flight sim designers have to say about a Korean war era fighter.

For MiG-9, the installation plays a big part for gases entering the jet intake.

If it's not to big a trouble, could you please point me to what TsAGI thinks about N-37? Ditto for MiG-9 shaking violently while firing 37mm?

 

[davparlr]

David, hit probability makes just a part of weapon's 'potency', the other part is effect (of a bullet/shell) upon the plane is hit.
For MiG-15, even at 600* rpm per 23mm gun, that makes 1200 rpg per plane, or 20 rps per plane. Mutiplied by 200g, that's 4 kg per second. For F-86, 120 rps per plane, multiplied by 46g per projectile, makes 5,52 kg. So Sabre fires greater mass from it's guns.
Now, how much a kg of cannon shell is worth of HMG bullets? Even if the ratio is 1,5 to 1, MiG-15 leads in effect on target. Then we add the 37mm (that one fires at same MV as 23mm, 690 m/s), 400 rpm -> 6,67 rps -> 4,9 kg per second.
So even if the Soviet cannons were firing ball ammo, they offer almost 9 kg per second of fire weight vs. Sabre's 5,52 kg. For same gun weight.

Throw weight is also on only part of the equation, velocity enters when calculating energy. We need to calculate the energy of the projectile at the moment of impact. I must apologize for not having all the data I need to calculate the actual impact energy on an airborne target. I do not know the termination velocity of 50 cal, 20 mm, 23 mm, or 37 mm projectiles at, say, 1000 ft at an initial platform velocity of 600 mph, at some altitude, and published muzzle velocity. Obviously, aircraft weapons ballistics is not simple. However, I can calculate the initial energy released by an aircraft with zero initial conditions.

50 cal., 46g (710gr), mv 2910 ft/min, energy 13,354 ft/lbs, energy per second (125 rps) 1,669,250 ft/lbs/sec.

23 mm, 200g (3086gr), mv 2265 ft/min, energy 34958 ft/lbs, energy per second (20 rps) 699160 ft/lbs/sec

37 mm, 735g (11342gr), mv 2260 ft/min, energy 128605 ft/lbs, energy per second (6.7 rps) 861654 ft/lbs/sec

Some items are apparent. One, while the 50 cal is only 23 percent of the 23 mm weight, initial energy is 38% of the 23 mm. Two, energy per second of the six F-86 50 cals is more than double the two Mig-15 23 mms, most likely greater than the 23 mm with explosives. Three, the total energy per second of the F-86 is greater than the 23 mm plus the 37 mm. This does not include explosives. Again, this is with initial velocity, and all of this could change if the velocity lost is calculated in.

Earlier I had shown that the Mig-15 had an 83% probability of one cannon hit (either 23 or 37 mm) with a one second burst and that the F-86 would get four hits with a probability of 88%. Comparing these values at initial conditions, the initial energy of the Mig-15 shell was 34958 ft/lbs for a 23 mm and 128,605 ft/lbs for the 37mm. The energy of F-86 hits would be four times 13,354 ft/lbs or 53416 ft/lbs. The F-86 does overpower the 23 mm (without explosives) and is over powered by the 37 mm. However, getting hit by that 37mm is really remote.

Here is a short note on the 37mm. It is a heavy projectile and I suspect does not have the same trajectory as the 23mm. I rather doubt that a Mig could target both the 23mm and 37mm at the same time.

Without having terminal velocity, this is all an approximation. However, I think it does show the power of the six M-3 machine guns and why the AF kept them. Here is another way of looking at it. I have never heard the P-47 being under gunned. You can take the P-47 armament, add 600 rounds per minute, put it on the center line (I read somewhere the Germans thought one gun on the center line was worth two in the wings) and you can get a feel for what was coming out of the nose of a F-86.

For Panther: 102g shell x 4 cannons x 11 rps = 4,49 kg per plane per second. Sabre throws 1/4 more mass, but Panther fires shells, not ball. Advantage Panther, that carries 200 kg of guns vs. 180 kg of Sabre.

I did my analysis based on Navy assessment of the 20mm vs .50 and probability of hits. I suspect that I will get a similar equality if I do the above calculations of energy. Maybe later, I am tired.

While USAF was installing HMGs in their fighters, it's also true that USN was quick to adopt all-cannon weaponry for their fighters, for same post war era. Since it seem impossible that both were right, I'll bet to USN. Other AFs moved for cannons in the same era, making USAF the only proponent of HMGs of that time.

Its not impossible at all, both chose to emphasize different variables and arrived at a close proximity.