Generally speaking...The Corsair, Hellcat, Spitfire, P47, P51. I guess when you consider... size, weight, recoil, number of rounds... the scales never got tipped in favor of the 20mm over the 50-Cal.? I have never heard what pilots thought about a gun with more machismo than the 50-Cal. The 50 sure was a potent weapon. The difference between the 30-Cal and 50-Cal has always seemed bigger to me than between the 50-Cal and 20mm. The stuff that the ...was it AP or API... 50-Cal round could penetrate, and set to flame was amazing. Was their much talk among USA fighter pilots regarding the want of a bigger gun than the 50-Cal for their fighter planes.? Thank You
The corsair took on 20mm later in its career...My understanding is that the 50cal was a good compromise between hitting power (20mm) and fire rate (to increase the chance of a hit amongst pilots with little experience). Make no mistake though, the 20mm was always a bigger and more dangerous round to be hit by...a dubious rule of thumb was two hits to a fighter with 20mm would spell some sort of catastophic failure (be it in the wing or tail or engine) and 4-6 on a bomber...i think this rule failed as the fighters and bombers became larger and better protected.
Here's a link to an article that explains some of it: http://www.quarry.nildram.co.uk/US404.htm More interesting and possibly relevant articles can be found at: http://www.quarry.nildram.co.uk/miltech.htm
The US clearly favored the . 50. With rare exceptions, the late Corsair, one 20 in the P-38 nose, a 37 in the P 39 and perhaps a few that slip my mind. Most everyone else had or moved toward 20's. The Spitfire and Hurricane started the war with 8- .303's, one version of the Hurricane, I believe the Mark 11 B increased that to 12 ! But both eventually moved to two 20's and 2 or 4 303's , the Hurricane even went to 2 -40's for ground attacks. The Germans favored, in general a mix of 2-20's and 2 8mm As the war progressed the Germans became more defensive and needed to shoot down bombers so 20 to 30mm cannon were more effective. The Brits and Americans needed to shoot down fighters so the .50 was pretty effective for the US and the mix for the Brits, All this from off the top of my head so errors are more than likely but the 20's seem to carry 60 plus rounds per gun with a lower cycle rate which meant fewer but more effective hits . I believe the P-47 carried 250 rounds her gun but was a huge fighter, it had 8 guns , the P-51 had 6. I believe I recalled the .303 planes carried 333 rounds/guns . The guns on the P-47 are clearly staggered to keep the belts from overlapping, I do not recall how the .303's work as they appear from the exterior to be aligned straight. Maybe they are staggered inside. Now how the Hurricane B managed 6 belts per wing is a mystery. 4 appear as normal, with two placed more outside. I guess it comes down to what you are trying to accomplish, the time in the war, and history. If I were a pilot I would rather my plane be hit by a .30 , next a .50, then a 20mm in that order but the likelihood of hits is in my favor per caliber.. Did not the Germans have a 15mm too ? On a ME 109/FW 190 how did the trajectories compare between the 8 and 20mm ? How were they zeroed in. ? Did the 20 run out before the 8 ? At least on the .50's they all fired to a common point, or should. Seems I remember the Tempest/Typhoon went to 4-20's . As for difference in sizes they would be , roughly, 7.62, 12.7 and 20. The bigger gap would be between the 12.7 and the 20 for diameter and the 20's seem to be proportionally longer. I am purely guessing but the .30 and .50 seem to have a better BC. There must be studies or threads on this interesting subject. Equally interesting is the 12-15 second supply of said ammunition.. Anyone know the cycle rate of a 20mm ? Nott WW 2 but I read a fascinating article of a Defense Forum about a Russian radar controlled cannon that would not fire unless the radar predicted a high hit probability. With few 30mm rounds on board certainly a good idea.
lwd, , I was busy typing with one finger while you were actually producing useful reading! Many thanks. Look like great articles and I am off to read. Gaines
Noted weapons expert Tony Williams has an analysis that quantified fighter armament weaponry effectiveness on his website. Most 20 mm cannons had three times the chemical content compared to 50 cal and a more favorable weight to destructive power ratio; the USN considered using the 20 mm Hispano as the standard weapon but US production models had reliability problems.
GTB...That is good "common sense" info...and is kind of what I thought. The 50 was a great, all-around compromise. I guess we all all seen Videos and Pictures of returning Fighters that were hit with both The German 50-Cal (12mm) and 20mm guns. Man-Oh-Man...those 20mm sure made a big hole. I can see where the 50 was a good choice though. Thanks
50 cal had no problems against fighter aircraft. 20 mm shells were more useful against bombers and the 30 mm was even better. The Germans mounted 30 mm guns on their late war interceptors for this purpose.
