Nickname: Old Friend
Posts: 255
Date: 3/24/04 18:17
The Browning .50 Cal as USAAF WWII Aircraft Armament
I don't have much of an informed opinion of this.
Why was the USAAF so "high" on the .50 machine gun as a primary fighter armament when by the end of the war, the Europeans had widely adopted the cannon?
I think I know of the .50:
- flat trajectory within reasonable ranges
- respectable rate of fire
- it wasn't a "light" armament
So why did the USAAF never adopt the widespread use of cannon armament on fighters, like the Europeans did?
Imagine a P-47 with 6 x 20mm cannon and ~200 rds/gun
My theories:
- Use of .50s gave a good combination of high-energy and ammo load (number of shots)
- Ligher weight and smaller size meant more guns for increased chance of hits
- A combination of guns and cannon was counter-productive because of differences of trajectories, although I believe a .50's trajectory would make for an ok cannon-"ranging" armament
- The .50 was very adequate for ripping-up Pacific Theater enemy aircraft and because of the higher production rate benifits of commonality, the .50 was it.
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Username: Seer Stuart
Nickname: The Prince of Darkness
Posts: 2345
Date: 3/24/04 18:40
Re: The Browning .50 Cal as USAAF WWII Aircraft Armament
I think the primary reason in WW2 was simply availability. The .50 was there, it was easily available and in mass production, there was a huge stock of ammunition and it did the job. It was powerful enough to punch through any armor on hostile aircraft and could deliver enough damage to bring them down.
Also, pre WW2, the US did experiment with cannon armament. They had two aircraft cannon, a 23 millimeter Madsen gun and the 37 millimeter. I understand that the 23 millimeter Madsen showed very little advantage over the .50 but was heavier and reduced ammunition stowage.
The 37 mm Madsen is a much more controversial weapon. It was planned for quite widespread use on bombers and fighters. Most famously, it was the nose gun on the P-39 Aircobra and the Russians don't stop singing its praises. I'm just readinga history of the Aircobra units now and they rate the P-39 as equal to an Me-109 with the great advantage of its 37 mm gun giving it single hit kill capability against German fighters (the Russians did not use the Aircobra for ground attack).
Nations do not survive by setting examples for others.
Nations survive by making examples of others
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Username: Mike Kozlowski
Nickname: BUFF Fan
Posts: 1895
Date: 3/24/04 20:19
Re: The Browning .50 Cal as USAAF WWII Aircraft Armament
tw-
As Stuart indicates, the Browning .50 was a remarkable blend of firepower, availability, ease of manufacture, and design that all happened to be at the right place at the right time. The USAAF did eventually do some work with 20mm cannons - the P-38 and the P-61 being the best known examples. In addition, IIRC some A-36/P-51B's got cannon installations, but for the life of me I cannot remember what size bore. Keep in mind also that the last generation of piston engined fighters would have carried 20mm cannon, most notably the F8F Bearcat and the F2G Super Corsair.
Stuart, the Marsden was a weapon with a very impressive punch, but it was (at least in US service) fairly tempramental. A very long time ago, I stood in freezing water up to my waist helping an EOD team from KI Sawyer AFB recover 37mm rounds that had been ejected - unfired - from P-39s that trained at what is now Oscoda-Wurtsmith IAP in Michigan. Seems as the cannons wore, they had a nasty tendency to push rounds through the breach, but not fire them. Still in their links, they'd go through the ejection chute and as the planes pulled up at the east end of the field (now Michigan Route 41 and Van Ettan Lake) they would be thrown from the aircraft and end up in the lake...which is where an ice fisherman found them one night.
Mike
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Username: Tomahawk6
Nickname: Unknown
Posts: 1649
Date: 3/24/04 21:46
Re: The Browning .50 Cal as USAAF WWII Aircraft Armament
I would only add this to the above points is that the .50 cal weighed less than a cannon and weight is important on any aircraft but more so on a bomber.
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Username: Sorivar
Nickname: Lord of the Cyber-Gnomes
Posts: 1598
Date: 3/24/04 22:07
Consider the Targets
No powers but the Allies had large numbers of airplanes like the B-17, B-24, Stirling, Lancaster and Halifax that required considerable amounts of fire power to bring down. The German fighters in particular (also Japanese and Italian fighters to a much lesser extent) began to get larger bore cannon later in WW II in an effort to effectively engage US and British Heavy Bombers. Even fighters like the P-47, Typhoon, and Hellcat required a fair amount of punishment and the German 7.9mm round and the Japanese 7.7mm round were ill-equiped to handle them.
The Allies, by contrast were not confronted by large masses of heavily armoured bombers in the Axis inventory. The JU-88, He-111, G4N and others are just not in the same category as even the B-25/26. The .50 cal and even the .303 are fine against them.
Only when jets came around did the US really move away from .50 cal. They didn't really have enough range or enough hitting power to handle the Mig-15 or enough power to handle later Soviet made heavy bombers like the Badger.
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Username: edgeplay cgo
Nickname: Old Friend
Posts: 1622
Date: 3/25/04 6:37
Re: The Browning .50 Cal as USAAF WWII Aircraft Armament
Perhaps more important, the ammunition weighed less and occupied less space. That meant you could carry more of it. This meant you could do a lot of shooting - important when you're shooting down more of them than they are of you. And vital for close air support.
Four to eight .50s makes a helluva mess when they strafe your convoy. .50 fire is effective against merchant ships and destroyers.
- Dennis
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Username: Nick Sumner
Nickname: Ex Hippy
Posts: 83
Date: 3/25/04 15:16
Re: The Browning .50 Cal as USAAF WWII Aircraft Armament
The US manufacturesrs had a hard time getting the 20mm hispano cannon to work properly and the British manufacturers had none spare to give them, which in effect forced their choice of fighter armament. Have a look at this link
http://www.quarry.nildram.co.uk/US404.htm
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Username: Larry
Nickname: Official USAF Sycophant
Posts: 711
Date: 3/25/04 16:30
Re: The Browning .50 Cal as USAAF WWII Aircraft Armament
I'll second what Mike said, but add that with alot of WWII, and even some Korea, pilots, their top three concerns in armament were, in order:
1. Rate of fire
2. Rate of fire
3. Rate of fire
Stuart alluded to this, but I think it needs to be stressed that the high rate of fire of the .50 cal, along with a reasonable punch (during WWII at least), were seen as greatly preferable to heavier cannon. It must also be remembered that in many WWII theaters, USAF aircraft were primarily dealing with fighters, or unarmored Japanese aircraft. Had USAF aircraft had to fight a more defensive war, against large groups of incoming bombers, cannon armament may have found its way to the fore.
"Out here in the middle,
where the center is on the right,
where the ghost of William Jennings Bryan,
preaches every night"
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Username: JPaulMartin
Nickname: Capitalist Pig
Posts: 455
Date: 3/26/04 2:21
Browning M3
Would something like the Korean-era Browning M3 be ideal for the US? From what I understand, RoF is 1200rpm, which means 2 M3s can fire as much as 3 M2s. Assuming total ammo load is kept the same (for the same firing endurance) then the designer could save a couple hundred pounds of guns and support structure, which could boost performance. Alternately, the weight of the third gun could be devoted to more ammo, and firing endurance could be increased while keeping performance constant.
Or is the above too big a disruption of the production line for too small a gain?
Jeff
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Username: Sea Skimmer
Nickname: Interstellar Warlord
Posts: 998
Date: 3/26/04 2:57
Re: The Browning .50 Cal as USAAF WWII Aircraft Armament
The M2 did weigh less then cannon, but when you compare the gun's weight to its rate of fire and weight of shell its pretty much the worst fighter weapon of the war, largely because it was very heavily built. That's nice with ground guns, but in the air no plane would ever survive long enough to use up more then a tiny fraction of the guns large life.
What we could have used is a lighten .50cal machine gun.
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Username: Seer Stuart
Nickname: The Prince of Darkness
Posts: 2355
Date: 3/26/04 3:05
Re: The Browning .50 Cal as USAAF WWII Aircraft Armament
Stuart, the Marsden was a weapon with a very impressive punch, but it was (at least in US service) fairly tempramental. A very long time ago, I stood in freezing water up to my waist helping an EOD team from KI Sawyer AFB recover 37mm rounds that had been ejected - unfired - from P-39s that trained at what is now Oscoda-Wurtsmith IAP in Michigan. Seems as the cannons wore, they had a nasty tendency to push rounds through the breach, but not fire them. Still in their links, they'd go through the ejection chute and as the planes pulled up at the east end of the field (now Michigan Route 41 and Van Ettan Lake) they would be thrown from the aircraft and end up in the lake...which is where an ice fisherman found them one night.
Interestingly the Russian P-39s had an ammunition tank for the empties, apparently to preserve CofG but 37 mm and .50 ammunition had to come all the way from the USA so reloading empties was a good thing. The primary complaint from the Russians about the P-39 was poor construction standards. Apparently replacing a few key components, especially in the engine significantly improved performance.
Nations do not survive by setting examples for others.
Nations survive by making examples of others
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Username: MBecker01
Nickname: Unknown
Posts: 18
Date: 3/26/04 12:36
Re: The Browning .50 Cal as USAAF WWII Aircraft Armament
Sorivar wrote:
Even fighters like the P-47, Typhoon, and Hellcat required a fair amount of punishment and the German 7.9mm round and the Japanese 7.7mm round were ill-equiped to handle them.
The Allies, by contrast were not confronted by large masses of heavily armoured bombers in the Axis inventory. The JU-88, He-111, G4N and others are just not in the same category as even the B-25/26. The .50 cal and even the .303 are fine against them.
Thats not logical. Axis cal. 30 ammo is not good enough for fighters, but allied cal. 30 ammo is even OK for bombers?!
edgeplay cgo wrote:
.50 fire is effective against merchant ships and destroyers.
If thats the case, 20mm ammo must be a real ship-killer.
About the P-39/63:
Look what I found about the P-39:
There was only one front where the P-39 enjoyed success, the Eastern Front in Russia. The USSR, like other countries, received aircraft from the United States through the Lend-Lease program; 4,773 of them were Airacobras. Unlike everyone else, the Russians loved the P-39. They stripped them of pilot armor and other "non-essentials" to reduce weight and enhance performance. The P-39 turned out to be well suited for combat on the icy Russian Front. Air combat there was at low altitude, where the P-39 performed best. Also, the USSR's air campaign consisted mainly of attacking ground targets, mostly tanks, other vehicles, and soldiers. This was the P-39s strong suit. Bell's fighter also enjoyed success, strangely enough, against the Luftwaffe. The German fighters, particularly the Bf 109, were high altitude interceptors, and their performance dropped considerably at lower levels. In Russia, German pilots were forced to face the Airacobra on its terms.
AFAIK the Russians did not change the engine.
Markus
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Username: Seer Stuart
Nickname: The Prince of Darkness
Posts: 2356
Date: 3/26/04 14:37
Re: The Browning .50 Cal as USAAF WWII Aircraft Armament
Thats not logical. Axis cal. 30 ammo is not good enough for fighters, but allied cal. 30 ammo is even OK for bombers?!
Perfectly logical - what Sorivar is pointing out is that there is a significant difference in target profile between the two. Where there is such a difference it results in assymetric ammunition preferences. Simple example; in shooting at people, if the target is wearing a bullet-proof vest, we need ammunition that penetrates said vests, if they are not, hollow-points are better.
If thats the case, 20mm ammo must be a real ship-killer.
Perhaps, perhaps not. Penetration, rate of fire, ammunition storage all come into the question as well - as does number of guns. Also it depends what 20 millimeter - the MG-FF in the Me-109E was little more than a grenade thrower - which made it very effective against unarmored targets but ineffective against armor.
Look what I found about the P-39:
Where? Providing the source would have been nice. However, this quote appears to be exceptionally unreliable. Based on "Attack of the Airacobras" by Dmitri Lorza we get the following.
They stripped them of pilot armor and other "non-essentials" to reduce weight and enhance performance.
Incorrect, the first models supplied were armed with a 37 millimeter and two .50s in the nose and two .30s in the wings. The .30s were removed and the Russians requested they not be installed in future deliveries. This was done at the factory. Thereafter the Russians used the aircraft as supplied.
The P-39 turned out to be well suited for combat on the icy Russian Front.
Incorrect, the P-39 was primarily deployed in the southern part of Russia, an area called the Kuban. Also, it first gained its reputation in the summer of 1942, not winter.
Air combat there was at low altitude, where the P-39 performed best.
In reality, the P-39 was considered a "high altitude" fighter and was used to supply top-cover for other aircraft. Interestingly, the P-39 was considered to have better high-altitude performance than the P-40. There is a detailed description of P-39 tactics in Attack of the Airacobras which makes this quite clear. they repeatedly describe the P-39s diving on German formations.
Also, the USSR's air campaign consisted mainly of attacking ground targets, mostly tanks, other vehicles, and soldiers. This was the P-39s strong suit.
Completely false. The Russian P-39s was never used for ground attack. This depiction of the Russian air effort as being primarily ground attack is wildly inaccurate. I suspect its a hangover from the bad old days when virtually all the information on Russian Front activity came from German sources. Those days are gone now and we have access to the Russian side of things.
he German fighters, particularly the Bf 109, were high altitude interceptors, and their performance dropped considerably at lower levels.
Again, this is false, comparison with action reports shows that the 1942 air battles over the Kuban took place at similar altitudes to those two years earlier during the Battle of Britain. The reason was quite simple - the fighting was intended to stop bombers reaching their targets and so it took place where the bombers were. And the loaded bombers (on both sides) flew at around 14,000 - 15,000 feet.
It's hard to say for sure since you didn't source the quote but it looks to me to be just a recycling of old legends that have been discredited now we have real access to the Russian side of things. Anyway, its not reliable.
AFAIK the Russians did not change the engine.
Nobody ever said they did. Where did you get that from? What they did do was that they found some of the components were faulty or inadequate so they replaced them with Russian equivalents. Items particularly quoted were seals, filters (especially oil filters) and bearings. The largest individual units to be replaced were fuel pumps. Bearing in mind all the spares had to come from Niagara Falls, that was probably inevitable; I suspect a lot of the replacements were made because the US-supplied components were unavailable and explained by the "ours is better" syndrome.
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Username: edgeplay cgo
Nickname: Old Friend
Posts: 1631
Date: 3/26/04 17:32
Re: The Browning .50 Cal as USAAF WWII Aircraft Armament
The primary complaint from the Russians about the P-39 was poor construction standards.
o/~ Oh don't give me a P-39
Oh don't give me a P-39
It will tumble, it will roll
It will dig a great big hole
Oh, don't give me a P-39. o/~
- Taught to me by an old WW-II Air Transport pilot, who used to ferry the things to Brasil. He obviously never managed to dig a great big hole, as he's still kicking.
Dennis
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Username: MBecker01
Nickname: Unknown
Posts: 19
Date: 3/26/04 17:33
Re: The Browning .50 Cal as USAAF WWII Aircraft Armament
Perfectly logical - what Sorivar is pointing out is that there is a significant difference in target profile between the two.
The target profile is very different. Sorivar said that "German 7.9mm round and the Japanese 7.7mm round were ill-equiped to handle" P-47, Typhoon, and Hellcat, but he considers "even the .303 are fine against" a Ju-88.
The same kind of ammo is not good enough to shoot down single engined fighters but OK for twin engined bombers? Was the P-47 was a kind of flying tank and the Ju-88 protected like the Zero?
Here is something I found on google:
http://home.att.net/~jbaugher1/p39_19.html
Airacobras in the Soviet Union
http://www.warbirdalley.com/p39.htm
http://www.scalecraft.com/browseproduct ... cobra.HTML
http://www.military.cz/usa/air/war/figh ... p39_en.htm
http://www.wpafb.af.mil/museum/research/p39.htm
http://home.att.net/~jbaugher1/p39_19.html
Markus
Btw: That engine/enigne parts thing was a misunderstanding.
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Username: edgeplay cgo
Nickname: Old Friend
Posts: 1632
Date: 3/26/04 17:37
Re: The Browning .50 Cal as USAAF WWII Aircraft Armament
.50 fire is effective against merchant ships and destroyers. If thats the case, 20mm ammo must be a real ship-killer.
I don't know. The high rate of fire of multiple .50s makes a lot of holes. Breaking up the boilers was usually the proximate cause of death, although rendering the crew's unifiorms unservicable was also significant. I don't know whether a 20mm would have gotten the number of hits as reliably.
- Dennis
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Username: Seer Stuart
Nickname: The Prince of Darkness
Posts: 2359
Date: 3/26/04 18:14
Re: The Browning .50 Cal as USAAF WWII Aircraft Armament
The same kind of ammo is not good enough to shoot down single engined fighters but OK for twin engined bombers?
Depends on the armored protection. The kill mechanism when using machine guns is hitting critical elements - usually interpreted as the pilot(s), fuel tanks, engines, key parts of the control system etc etc. Now, there are two parts to such an equation. One is actually hitting the vital component, the other is damaging it once hitting it.
Taking the first. Where bullets hit on an aircraft is essentially a matter of chance (I know that there is much written about aiming for and hitting specific components but people actually able to do it were very rare). In reality, bullets hit the target at random. Therefore, the more bullets hit the target aircraft, the greater the chance that one or more of them will hit something vital. All other things being equal, its better to hit the aircraft with two small bullets than one big one (the pilot will not be particularly concerned about the difference between getting a .3 inch and a .5 inch bullet between his eyes). That was the reason why the British went to batteries of eight .303 machineguns in the early Spitfires and Hurricanes. They wanted to fill the target with as many bullets as possible, aware that the more hits they scored, the greater the chance of one being the vital one.
Now lets look at another factor. Size. Assuming that the vital targets within two aircraft are of the same volume, the larger aircraft will have an edge. Becuae the vital volume in the larger target is a smaller percentage of the volume as a whole than in a smaller aircraft, if the two are hit by the same number of bullets, there is a smaller chance of them hitting something in the larger aircraft. Thus, to give an even chance of hitting a vital element, we have to pour more bullets into larger targets. That again benefits weapons with a high rate of fire and shows the truth behind Larry's comment about rate of fire.
However, if the volume of vital components in the larger aircraft is much larger than in the smaller aircraft (say four crew as opposed one, two engines as opposed to one, bigger fuel tanks, bigger oil tanks, etc etc) then the chance of a given number of bullets striking something vital becomes greater. Now we see the true relation between various types of target
All other things being equal, the measure of vulnerability of an aircraft to machinegun fire is directly proportion to the percentage of the target's total volume occupied by critical elements
So, using your Ju-88 and P-47 example, it doesn't matter whether one is a tank and the other a spiders web or not. If the P-47 has 25 percent of its total volume occupied by vital elements and the Ju-88 33 percent, the P-47 is less vulnerable to machinegun fire.
Now we go to the other consideration, damaging something after hitting it. When the British elected to use 8 .303 machineguns, aircraft by and large were not armored. That changed although not as fast as sometimes believed ( the stories from the Battle of Britain of German bombers flying after being hit by hudnreds of machinegun rounds are mostly false - what actually happened was the pilots simply missed. British fighter pilots were dreadfully bad at shooting.). Anyway, so if we score a hit on a vital area, we have to damage it. The obvious answer is to protect the vital areas with armor. Now another obvious comment. For a given weight of armor, the smaller the area of being protected, the more heavily that area can be protected. Thus, for a given weight of armor, whether the vital areas can be protected against a given weapon depends on how great the volume of those areas is.
So, in order to determine the relative vulnerability of the P-47 and the Ju-88 to hits in vital areas we have to know (a) what weight of armor was protecting those vital areas and (b) what the volume of the vital areas was. If (purely hypothetically) it turns out the P-47 had half the weight of armor that a Ju-88 had but it was protecting onlya third of the area, then the P-47 is actually better protected.
Hence the importance of what I described as target profiles.
Was the P-47 was a kind of flying tank and the Ju-88 protected like the Zero?
If you followed through the analysis above, you know know the answer. Maybe. We don't have the figures needed to tell us. However, the answer isn't nearly as simple as you make out.
If you read the Baugher quote it mostly confirms what I said. Lorza's history of the Airacobra disagrees on the the relative merits of the 20 millimeter and 37 millimeter - his book states categorically that the Russians preferred the 37 millimeter due to its hitting power. Lorza's book is based on interviews with surviving Russian P-39 pilots and the records of the regiments and divisions that were equipped with the aircraft. Its therefore primary research material. Baughers is a secondary source and I would therefore take Lorza's word. The others you quote are tertiary or quaternary and the Internet is hardly research-grade reliable anyway.
Nations do not survive by setting examples for others.
Nations survive by making examples of others
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Username: Sorivar
Nickname: Lord of the Cyber-Gnomes
Posts: 1601
Date: 3/26/04 18:53
The difference is the target not the gun
The JU-88 is not very well armoured for an aircraft of it's size, particularly in the early models. It was built for speed more than defense.
The .303 machinegun is adequate against it.
The B-17 is well armoured and is much larger than a twin engined aircraft.
The .303 machinegun is inadequate against it.
The G4M Betty is basically unarmoured and a flying fuel tank.
Just about any machine gun is effective against it.
The P-47 is a flying tank, well armoured and large for a single engine fighter.
The .303 machinegun is inadequate/marginal against it.
The Zero-sen is much like the Betty only a single engine plane.
The .303 is effective against it.
It is not the nations gun that is at issue in this case. The Machine gun could be the Japanese 7.7mm or the German 7.92 or the British Browning .303 and they'd be effective against the Betty, Zero or JU-88 but not against the B-17 or P-47.
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Username: MBecker01
Nickname: Unknown
Posts: 20
Date: 3/26/04 18:58
Re: THX for the explanation. (no text)
mmm
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Username: Theodore
Nickname: Resident Vexillologist
Posts: 1960
Date: 3/26/04 21:57
Re: The Browning .50 Cal as USAAF WWII Aircraft Armament
the Russians did not use the Aircobra for ground attack
Say what? I thought that was why they loved the thing.
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Username: Seer Stuart
Nickname: The Prince of Darkness
Posts: 2361
Date: 3/26/04 22:14
Re: The Browning .50 Cal as USAAF WWII Aircraft Armament
Say what? I thought that was why they loved the thing.
So did I, for many years. So did everybody. The only thing is, it wasn't true. P-39s were never - never - used for ground attack by the Russians. Over the Kuban, the operational pattern was that the P-39s flew top cover, close escort was provided by P-40s and Russian fighters and ground attack was done by Il-2s and other light bombers.
I would say that almost everything we read about the P-39 in Russian hands is wrong. A few intersting things I've learned.
The P-39s had a specific operational formation called "The Bookcase" this was three flights of six P-39s stacked vertically at 1,000 foot intervals. As they peeled off to dive on the enemy formations, they'd automatically drop into three waves and go through the enemy formation like that.
The Russians re-rigged the firing switch so they could let fly with all three guns simultaneously. Previously, the pilot could fire either the machineguns or the cannon (technically it was possible to squeeze both buttons but it was hard work.)
Once a P-39 went into a spin, getting out again was very hard. Could be done but it needed a lucky pilot
The P-39 was the first aircraft in Russian service to have a radio all of its own. In fact it had "five" (actually three transmitters, two receivers). The Russian pilots considered the radio as a weapon along with the cannon and machine guns.
People who are interested in the P-39 should get "Attack of the Airacobras" Its a long overdue look at how the Soviets used the aircraft and why they liked it so much.
Nations do not survive by setting examples for others.
Nations survive by making examples of others
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Username: edgeplay cgo
Nickname: Old Friend
Posts: 1640
Date: 3/26/04 23:32
Re: The Browning .50 Cal as USAAF WWII Aircraft Armament
Once a P-39 went into a spin, getting out again was very hard.
... It will dig a great big hole.
The Russian pilots considered the radio as a weapon
No fools, those Russkies.
- Dennis
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Username: MarkSheppard
Nickname: Old Friend
Posts: 155
Date: 3/26/04 23:33
Re: The Browning .50 Cal as USAAF WWII Aircraft Armament
The Fifty Cal was I think, the perfect general purpose aircraft armament of World War II, when employed in the USAAF/USN's typical battery of six wing gun because you sprayed a LOT of lead into the air, and the dispersion because of the wing locations ensured you'd hit at least SOMETHING, and when all six of them hit the target, the results were devastating, like wings being sawed off FW-190s in midair, etc.
I find in flight simulators, that the USAAF fighters are the easiest to score kills with, as opposed to the russian and german fighters, all you have to do is pull in a turn ahead of your opponent, get him juuust below the gunsight pipper in a turn and mash the firing button, and watch him spin out of control as your spray of fire impacts him.
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Username: Allen Hazen
Nickname: Old Friend
Posts: 287
Date: 3/27/04 6:51
P-39
The ditty about "It will tumble and spin, and auger right in,and dig a big hole in the ground! Oh! don't give me a P-39" is quoted in "Yeager," Chuck Yeager's autobiography. It also comes out that Yeager LIKED the P-39: unlike most of his squadron mates, he would have been happy to fly it in combat, and he bosts of doing airobatics in one at an airshow postwar.
Is it possible that the P-39 needed a more skillful pilot than other WW II types? To keep it from tumbling and rolling and spinning?
Leading to another thought. WW II in the air was fought by what would now be thought of as very hastily trained pilots. So (thinking out loud here, with no real knowledge) one of the essential features in a "great" WW II airplane would have been... being readily tamed by pilots NOT in the 95th percentile of skill?
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Username: Seer Stuart
Nickname: The Prince of Darkness
Posts: 2368
Date: 3/28/04 17:25
Russian Sturmoviks
Theodore - Say what? I thought that was why they loved the thing.
Stu - So did I, for many years. So did everybody. The only thing is, it wasn't true. P-39s were never - never - used for ground attack by the Russians.
Turns out I was a more than a little over-emphatic there. On April 16th 1945, orders were issued that, due to the complete absence of enemy air opposition, all Soviet fighters were to conduct ground attack sorties. Accordingly, between April 25th and May 8th 1945, Soviet P-39s flew ground attack missions, primarily using RRAB-70 cluster bombs (they had no armor piercing ammunition for their 37 millimeter guns).
Couple of other little extracts. On the "Icy Northern Front" issue, it turns out that the P-39 was assigned to the southern fronts because the booster coils on the Allison engine were inefficient and failed in cold weather. When the temperature dropped below zero, the Allison engine couldn't be started at all.
The recurring refrain through all the stories of maintaining and supporting the P-39 is correcting poor workmanship and construction standards. It makes me wonder how much of the Airacobra's poor reputation in US service was due to poor design and now much to manufacturing deficiencies.
Nations do not survive by setting examples for others.
Nations survive by making examples of others
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Username: Theodore
Nickname: Resident Vexillologist
Posts: 1970
Date: 3/28/04 19:01
Re: Russian Sturmoviks
I was not aware that the cluster bomb existed in WWII. Can you expand on its development?
Were the Russian complaints about the P-39 centered on the engine or were there other major problem areas?
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Username: Seer Stuart
Nickname: The Prince of Darkness
Posts: 2372
Date: 3/28/04 19:51
Re: Russian Sturmoviks
I was not aware that the cluster bomb existed in WWII. Can you expand on its development?
I knew the Germans used canisters of small bombs but I wasn't aware of the RRAB-1. "It was a 70-kilogram weapon that contained 35 to 40 bomblets. The container had a small windmill device . After bomb separation from the aircraft, this began rotating and, at a specified altitude, triggered a mechanical detonating device that blew open the bomb container. The bomblets then dispersed in the air and spread out to cover the area of the target."
Typically the RRAB-70 was dropped from about 300 meters and each bomblet had a lethal radius of 25 - 50 yards for personnel and 25 - 30 yards for vehicles (presumably that means soft-skins.
The US shipped 1,232,991 rounds of shell, 37 mm M54 high explosive to the USSR during WW2. The US supplied 65,380 M80 armor-piercing rounds to the UK but none to the USSR. There are interesting questions there. Was the Airacobra's 37 mm ammunition interchangable with that on the M3 light tank? If not, why did the UK get so much AP ammunition for an aircraft they didn't use? If the ammunition was interchangable, didn't the USSR get AP ammunition for its 37 mm armed lend-lease tanks?
Were the Russian complaints about the P-39 centered on the engine or were there other major problem areas?
It seems to be across the board. The aircraft suffered tail unit failures that were due to poor workmanship in structural assembly, instrument installation problems, defective wiring etc etc. I think Bell's Niagara Falls factory has some hard questions to answer - its interesting it was almost immediately shut down post-war and was never re-opened.
The Allison engine problems may be additional to that litany - one of the post-war problems with the F-82 Twin Mustang was the shift from Packard Merlins to Allison engines and the discovery that extremely poor workmanship made the Allisons unreliable (to the point where then F-82 was on the verge of being cancelled).
Makes one wonder what would have happened if somebody had put a Packard Merlin into a P-39.....
Nations do not survive by setting examples for others.
Nations survive by making examples of others
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Username: edgeplay cgo
Nickname: Old Friend
Posts: 1645
Date: 3/28/04 21:16
Re: Russian Sturmoviks
The US shipped 1,232,991 rounds of shell, 37 mm M54 high explosive to the USSR during WW2. The US supplied 65,380 M80 armor-piercing rounds to the UK but none to the USSR. There are interesting questions there. Was the Airacobra's 37 mm ammunition interchangable with that on the M3 light tank? If not, why did the UK get so much AP ammunition for an aircraft they didn't use? If the ammunition was interchangable, didn't the USSR get AP ammunition for its 37 mm armed lend-lease tanks?
There's a third possibility. The ammunitions are not interchangeable, but the author mised the difference.
- Dennis
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Username: Seer Stuart
Nickname: The Prince of Darkness
Posts: 2373
Date: 3/28/04 21:55
Re: Russian Sturmoviks
There's a third possibility. The ammunitions are not interchangeable, but the author missed the difference.
Very good point - so now we need to know (a) about the 37 millimeter guns in general and (b) about the M54 and M80 rounds for those guns.
**EDIT**
I did a check around. The M4 and the M9 were the 37 millimeter guns on the P-39. The M54 and the M80 were the ammunition for those guns. I found
http://www.wwiivehicles.com/html/usa/guns.html
This table
that gives lots of information but it isn't clearly laid out; I can't work out whether its saying the ammunition was or was not interchangable. So, can anybody who ahs a detailed knowledge of tanks help out here??
Nations do not survive by setting examples for others.
Nations survive by making examples of others
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Username: Guilherme Loureiro
Nickname: Unknown
Posts: 297
Date: 3/28/04 22:10
Re: Russian Sturmoviks
IIRC, the 37mm ammo used by the P-39 was shorter than the ones used by tanks; the numbers 37x139 and 37x227 keep coming to mind, but don't take my word for it - they are almost certainly wrong.
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Username: Sea Skimmer
Nickname: Interstellar Warlord
Posts: 1001
Date: 3/28/04 23:04
Re: Russian Sturmoviks
The M9 aircraft cannon fired 37x223SR, which included the M54 and M80 rounds. The M4 cannon however fired the 37x145R cartridge.
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Username: A G Williams
Nickname: New Guy
Posts: 1
Date: 3/29/04 7:43
Re: The Browning .50 Cal as USAAF WWII Aircraft Armament
Correct - the M4 cannon used in the P-39 and early P-63 used the 37x145R ammo, as did the M10 used in the later P-63. AP ammunition was available for these guns but it appears that it was not sent to the USSR. Incidentally, the M4/M10 weren't Madsen designs but came from John Browning and were made by Oldsmobile.
The M9 did use the much more powerful 37x223SR ammo from the M1A1 AA gun (it was a modified, belt fed version of that gun) which was almost but not quite the same as the 37x223R ammo used in US tank/anti-tank guns. However, the M9 was only experimental and was not used in service aircraft.
You'll find details, illustrations etc of the ammo on my website, as well an analysis of the effectiveness of WW2 fighter armament and an explanation of why the USA made so little use of the 20mm cannon.
Tony Williams: Military gun and ammunition
http://www.quarry.nildram.co.uk
website
http://forums.delphiforums.com/autogun/messages/
and discussion forum
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Username: A G Williams
Nickname: Unknown
Posts: 2
Date: 3/29/04 7:52
Re: The Browning .50 Cal as USAAF WWII Aircraft Armament
Six .50 were certainly effective against fighters, but at a significant cost in weight. The bullets lacked the significant HE/I content of cannon shells, which made the cannon more efficient. So the usual RAF quartet of 20mm cannon weighed about the same as six .50s but was about twice as destructive.
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Username: Hoahao
Nickname: Unknown
Posts: 1556
Date: 3/29/04 13:17
Re: Russian Sturmoviks
I'll be happy to conjecture too!!
The load of armor piercing ammo destined for the USSR might be sitting on the bottom curtesey of the German navy; since strafing tanks was from above, the armor might have been thinner there and armor piercing rounds might not have been considered necessary. I'm thinking of the area over the engines.
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Username: Seer Stuart
Nickname: The Prince of Darkness
Posts: 2375
Date: 3/29/04 15:21
Re: The Browning .50 Cal as USAAF WWII Aircraft Armament
This is fascinating - so why did the US send 60,000 plus rounds of AP ammunition that was unique to the Airacobra to the UK???????
Could it something as simple as a clerical error??
Another thought; didn't the P-39s supplied to the UK have a 20 millimeter cannon in place of the 37? If so, why did the UK get Airacobra 37 millimeter ammunition at all??
Nations do not survive by setting examples for others.
Nations survive by making examples of others
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Username: Scott Brim
Nickname: Technocrat
Posts: 525
Date: 3/29/04 16:14
Clerical errors and scale of supply
In World War II, my mother spent some time working in a railroad dispatching center. It wasn't unusual for an entire trainload of supplies to be misdirected to the wrong destination. But the scale of supply was so huge that it didn't seem to matter if here and there a misdirected train sat on a siding for awhile until it could be sent to the right place.
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Username: Philistine
Nickname: Unknown
Posts: 82
Date: 3/30/04 2:30
Re: Russian Sturmoviks
"Makes one wonder what would have happened if somebody had put a Packard Merlin into a P-39"
On the one hand, the difference between the Allison-engined P-51A and the Merlin-engined P-51B was dramatic. On the other hand, the difference between the P-40E (Allison) and P-40F (Merlin) was negligible. The P-39 looks pretty clean, which should work in its favor, but I just don't know. Also, I don't know what the odds would be of shaking loose a spare Merlin for a plane the USAAF had already given up on.
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Username: Theodore
Nickname: Resident Vexillologist
Posts: 1973
Date: 3/30/04 3:49
Re: Russian Sturmoviks
Not all Merlins were created equal. The Merlin in the P-40F had a single-stage supercharger - the Merlin in the P-51B had a two-stage supercharger. That's the difference in high-altitude performance, which is where the Allison gave up a lot of ground performance-wise. (Reliability, of course, could only be improved with any non-Allison engine.)
The really fascinating idea to me is that of a Merlin-engined P-38. There are a lot of people who would say the Lightning was the best low-altitude fighter of the war (not that it was any slouch up high); now if it could have had engines with great high-altitude performance too...
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Username: Philistine
Nickname: Unknown
Posts: 83
Date: 3/30/04 4:56
Re: Russian Sturmoviks
I'm not sure switching to the Merlin - even with the two-stage supercharger ala the P-51 - would net that great an improvement over the turbocharged Allisons in the P-38. The Lightning's big problem with high altitudes was with its cooling arrangements: once those were worked out in the P-38J, the turbocharged Allisons were able to achieve their full rated power all the way from sea level up to 27,000 feet.
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Username: A G Williams
Nickname: Unknown
Posts: 3
Date: 3/30/04 7:26
British testing of 37mm AP
Large numbers were often involved in supplying items which might not have been needed. For instance, a factory in the USA was kept happily occupied churning out thousands of drum magazines for the Hispano long after they had all been converted to belt feed. Tens of thousands of US Hispanos were sent to the UK, who never used them.
The 37mm AP was tested in the UK: this is an extract from 'Flying Guns: World War 2' by Emmanuel Gustin and myself.
"The problem was that most aircraft were not well suited to carrying a large cannon. Some single-engined planes were able to fit a large gun in the nose, firing through the hollow propeller hub. However, this usually required the use of a liquid-cooled vee engine, the cooling system of which was vulnerable to damage from ground fire. This could be surmounted (as in the Il-2) but only by accepting the performance-draining weight penalty of comprehensive armour plating. The exception was the unique configuration adopted by the Bell P-39 Airacobra and P-63 Kingcobra, with the engine behind the pilot therefore leaving the nose clear for heavy gun armament. Unfortunately for this purpose, the Bells had liquid-cooled engines anyway, and although most of them mounted a 37 mm M4 or M10 cannon, these were low-velocity guns with a poor AP performance. The official figures were 20-25 mm / 450 m / 70 (depending on the armour type) but the British tested the weapon with an allowance for the extra velocity resulting from aircraft speed and achieved 35 mm / 360 m / 80."
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Username: Hoahao
Nickname: Unknown
Posts: 1558
Date: 3/30/04 12:51
Re: British testing of 37mm AP
Interesting. The German Mark 4 had only 10mm of armor thickness on top of the hull. A puncture of 30mm of armor is sufficent to take care of a Panther. Any figures on the armor piercing qualities of non AP shell??
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Username: A G Williams
Nickname: Unknown
Posts: 4
Date: 3/30/04 13:01
Re: British testing of 37mm AP
The penetration of the HE shells would have been relatively low. Also, don't forget that the AP penetration figures were for an 80 degree strike (i.e. almost head-on). In practice, fighter-bombers tended to attack in shallow dives of not more than 30 degrees, and the penetration was drastically reduced as the striking angle grew more shallow. I have no comparable figures for the 37mm, but the .50 Browning AP could penetrate 20-25mm at 90 degrees but only 5mm at 30 degrees.
To be sure of a roof/engine deck penetration, the P-39 would have to be in a suicidally steep dive.
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Username: Hoahao
Nickname: Unknown
Posts: 1561
Date: 3/30/04 14:00
Re: British testing of 37mm AP
"The official figures were 20-25 mm / 450 m / 70..."
I would consider the above as realitively shallow; I wouldn't think 45 degrees excessive, but what do I know. That aside, you have the effect of the shallow attack on the tracks/running gear at a 80% angle of attack. Simply rendering the tank unable to move would be helpful.
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Username: A G Williams
Nickname: Unknown
Posts: 5
Date: 3/30/04 14:24
Re: British testing of 37mm AP
There are unfortunately two different conventions for measuring penetration angle, which can lead to confusion: one takes the most favourable angle (perpendicular to the armour) as 90 degrees, one as 0 degrees. The figures I have quoted use the former measurement, so a 70 degree angle isn't far off the perpendicular and will be little different from the best possible result.
You are right about the ability to damage tank tracks, but the 37mm M4 was a relatively low-velocity gun with a rainbow-like trajectory at strafing range. It was also slow-firing, so scoring hits on a small target like a tank track would have been very difficult.
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Username: JPaulMartin
Nickname: Capitalist Pig
Posts: 460
Date: 3/30/04 15:08
Re engined Lightnings
If we are going to be re-engining the Lightning, why not go whole hog and switch to a nice relaible turbocharged US radial? R-2600 or 2800 would probably be overkill (but it would be coooool) so how about using a late model R-1830? The engine it self was slightly heavier than the Allison, but you can loose the weight of the cooling system.
Jeff
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Username: Larry
Nickname: Official USAF Sycophant
Posts: 722
Date: 3/30/04 17:05
Re: Re engined Lightnings
There was an attempt to produce a Lightning variant powered by radial engines, the XP-58. Various radials were considered, including the R2800 and Wright R-2160 Tornado. Neither provided sufficient performance benefit, and the Tornado project eventually collapsed. The aircraft was ultimately equipped with a 24 cylinder Allison V-3420, which was a disaster in its own right. The project demonstrated that it wasn't really possible to modify a Lightning with radials and gain a sufficient performance advantage, and that the changes required to incorporate the radials resulted in an aircraft that was completely different from the original.
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Username: M21A1 Sniper
Nickname: Unknown
Posts: 559
Date: 3/30/04 18:28
Re: British testing of 37mm AP
37mm HEI would be generally inneffective vs tanks, but pretty darned lethal vs everything else.
The 37mm of the P-39 is an Oldsmobile produced version of a John M. Browning design(as earlier stated). I saw the original(as in the prototype handmade by J. Browning himself) 'in the white' displayed at the Browning firearms museum in Ogden Utah less than a year ago.
Wasn't the IL-2's primary weapon also a 37mm gun?
I once saw an interview with Yeager where he stated that the P-39 was the most manueverable US fighter of WWII at low altitudes and would run circles around a mustang down in the dirt. He also stated the 37mm shell had such a low velocity that the individual rounds were visible in flight(it helped that they were about the same size as a grapefruit, lol).
On another note, the .50 stayed around well into the jet age, and it proved entirely capable of ripping the Mig-15 to shreds over the skies of Korea. It had significantly greater range and velocity at the kinds of altitudes that the F-86 and Mig-15 operated as opposed to the typical fighters of WWII.
Saw an interview once where a newbie Korean war USAF pilot(who was himself a USMC WWII ace) saw his first combat against the Mig-15 with a USAF multiple ace as formation lead.
He stated he thought the Ace was 'a moron' because he opened up at a range 'well outside the .50's envelope'....until he saw the rounds tearing into the mig.
Thin air does wonders for increasing velocity, hence flattening trajectory and increasing KE.
PS... a dual stage supercharger is FAR more efficient than a single stage.
Interesting that no one mentioned that the P-39 was a mid-engined design....it was behind the pilot.
"US Snipers-Providing surgical strikes since 1776"
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Username: Seer Stuart
Nickname: The Prince of Darkness
Posts: 2381
Date: 3/30/04 18:35
Re: British testing of 37mm AP
You are right about the ability to damage tank tracks, but the 37mm M4 was a relatively low-velocity gun with a rainbow-like trajectory at strafing range. It was also slow-firing, so scoring hits on a small target like a tank track would have been very difficult.
Another comment from "Attack of the Airacobras" was that Russian pilots were taught to fire from extremely close range. I suspect thats why they had no objection to the low muzzle velocity and low rate of fire.
Nations do not survive by setting examples for others.
Nations survive by making examples of others
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Username: M21A1 Sniper
Nickname: Unknown
Posts: 561
Date: 3/30/04 18:45
Re: British testing of 37mm AP
Apparently their balls were as big as the munitions they were firing eh stuart?
"US Snipers-Providing surgical strikes since 1776"
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Username: Seer Stuart
Nickname: The Prince of Darkness
Posts: 2382
Date: 3/30/04 19:26
Re: British testing of 37mm AP
One gets that impression reading the book. The typical instruction was to hold fire until the target aircraft "filled the windscreen". Its startling how many Russian pilots ended up ramming German aircraft
Nations do not survive by setting examples for others.
Nations survive by making examples of others
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Username: techwriter
Nickname: Old Friend
Posts: 261
Date: 3/30/04 22:22
Re: British testing of 37mm AP
This website,
http://www.2worldwar2.com/erich-hartmann.htm
credits Eric Hartmann as saying: "'Detect - Decide - Attack - Disengage '. He used to close in and 'When he fills the entire windscreen you can't miss'".
Several aces had the same opinion. I believe Donald Blakselee said it best which went something like: Fly right up his *ss, and then let him have it.
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Username: Norman Yarvin
Nickname: Old Friend
Posts: 118
Date: 3/30/04 22:31
Gotta be incompatible cartridges
Anything that is describable as a "low-velocity" gun is not going to be able to fire the HE M54 round in that table, which is listed as having a muzzle velocity of 2600 fps, nor the APC M80 (at 3080 fps). The cartridge for the higher-velocity gun will be much bigger and contain much more powder; it won't come close to fitting in the smaller chamber of the lower-velocity gun. The projectiles might be interchangeable, but not the cartridges.
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Username: A G Williams
Nickname: Unknown
Posts: 6
Date: 3/31/04 7:14
Re: Gotta be incompatible cartridges
Indeed they are - see my other posts.
Some books on the P-39 contain wrong information in saying that they were equipped with the 37mm M9 cannon, which did use the high-velocity 37x223SR ammunition giving the performance you describe.However, the plane only used the M4 and M10 guns which fired the same 37x145R ammunition with a muzzle velocity in the region of 2,000 fps.
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Username: A G Williams
Nickname: Unknown
Posts: 7
Date: 3/31/04 7:23
Re: British testing of 37mm AP
The Il-2's primary gun was the 23mm VYa-23, but some later models carried a pair of 37mm NS-37. These were considerably more powerful, as far as faster firing, compared with the M4, but the heavy recoil threw off the aim. Details of tankbusting guns, their performance and planes are here:
http://www.quarry.nildram.co.uk/tankbusters.htm
The USAAF's battery of .50s was good for anti-fighter work in WW2, but showed deficiencies in Korea. Basically, the armament of both the MiG-15 and the F-86 was not ideal for quite different reasons; the MiG's 23mm and 37mm cannon were very effective when they hit, but were slow-firing low-velocity pieces difficult to hit with (and with different trajectories). The fast-firing, high-velocity .50 M3s could hit easily enough, but it took a lot of hits to bring down a MiG - over 1,000 rounds fired per plane. Late in the war the USAF ran Project GunVal, which involved testing 20mm cannon fitted to F-86s. This proved the best solution and was adopted afterwards.
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Username: M21A1 Sniper
Nickname: Unknown
Posts: 568
Date: 3/31/04 8:22
Re: British testing of 37mm AP
I don't dispute that the 20mm is superior for shooting down jets by any means- simply pointing out that the .50BMG shot down a whole lot of jets over Korea.
BTW, good to see ya still around AG...been a while.
"US Snipers-Providing surgical strikes since 1776"