1. #1
    You forgot the P-38. Heh.

    The USAAF was fighting a war against fighters. We had very very little bombers to shoot down. The .50 cal's I think are better suited in that way then 20MM due to its higher ROF, more weapons, more ammo, better chance of hitting.

    We also had the P-61 had 4 20MM and 4 .50 cal.
    Share this post

  2. #2
    Originally posted by Gibbage1:
    You forgot the P-38. Heh.

    The USAAF was fighting a war against fighters. We had very very little bombers to shoot down. The .50 cal's I think are better suited in that way then 20MM due to its higher ROF, more weapons, more ammo, better chance of hitting.

    We also had the P-61 had 4 20MM and 4 .50 cal.
    The P-61 was a bomber-killer, though, totally in agreement with your theory. Yeah, I think it makes alot of sense - it didn't take much to knock a fighter down, spraying 50 cals was probably an easier way to get a kill than placing a cannon round on your target.
    Share this post

  3. #3
    Infrastructure and technological inertia had a lot to do with it as well, as did a lack of indigenous weapons to supplant the .50.

    The .50 worked well, and was appropriate for the job: A to A gunnery against lightly armoured targets. If the USA had gone up against 4 engined heavies, I suspect it would of been replaced by something heavier. The USNs late war fixation with fitting cannon to its fighters probably has a lot to do with its desire to stop Kamikazes as effectively as possible.


    Potential replacements were the .60 cal (15.25mm) very heavy machine gun (a high velocity redesign of the German MG 151/15 15mm) and the ANM2 20mm (A US copy of the Hispano). However, these never really got off the ground during the majority of the war, due to a variety of issues, some industrial, some institutional, some political. So there was no real alternative to the multiple .50 cal installation for US fighters. Through the war period various calibres (37mm, 23mm,

    US fighters were moving towards banks of HMGs as standard armament while other nations (France, Britain, Germany, Russia, and Japan to a lesser extent) went to the single/ paired 20mm. Its just a different approach to the same problem given the external constraints; putting the most amount of high velocity lead and high explosive onto the target in the shortest amount of time.

    Take a look at this article for a better explanation: http://www.quarry.nildram.co.uk/US404.htm
    Share this post

  4. #4
    WOLFMondo's Avatar Senior Member
    Join Date
    Dec 2003
    Posts
    4,910
    I'd say ISD's infrastructure has allot to do with it. If you start putting different guns in planes you have to re tool factories, retrain the workers, change supply chains, change shipping logistics, retrain all your pilots in how to use and fire the new gun, retrain all the ground crews in using and maintaining the guns, you have multiple stock piles of ammunition, guns and spare parts etc. It would have been a huge task to do this.

    The US sticking mainly with the .50 in the European theatre meant all hit had to do was ship one type of ammunition in, supply one type of gun, spare parts for one gun only, train crews and pilots in one guns use and mainenance.
    Share this post

  5. #5
    p1ngu666's Avatar Senior Member
    Join Date
    Aug 2003
    Posts
    11,199
    all the reasons above
    european aircraft where bulit as interceptors too, while the american designs where too, just abit different, the european ones upgraded from mostly rifle calibre, to 20mm cannons, the americans never had a pressing need too.

    think even the 190's started off with 4 mg guns or something fairly weedy
    Share this post

  6. #6
    p1ngu666's Avatar Senior Member
    Join Date
    Aug 2003
    Posts
    11,199
    apart from the uk, france, russia

    prewar thinking was that the bomber would always get through...
    Share this post

  7. #7
    Aaron_GT's Avatar Senior Member
    Join Date
    Dec 2003
    Posts
    6,134
    US fighters were moving towards banks of HMGs as standard armament while other nations (France, Britain, Germany, Russia, and Japan to a lesser extent) went to the single/ paired 20mm.
    Actually the UK went for quad 20mm cannon, if you look at the flurry of mid-1930s specifications that were issued. So in 1937 there were quad cannon Hurricane and Spitfire designs around, as well as the Whirlwind and other aircraft. In the end the Spitfire went for, typically, only 2 20mm cannon, but almost everything else had 4.

    It is quite interesting why, the ME109E was cannon armed in 1939 & there was no serious bomber threat to the 3rd Reich at that stage
    It was still assumed that the 109E, as well as clearing paths for German medium bombers would have to defend the forward echelons of the Wehrmacht against other medium and light day bombers.
    Share this post

  8. #8
    Kocur_'s Avatar Senior Member
    Join Date
    Jun 2005
    Posts
    1,793
    The reason is quite sipmle: there was no other gun in the US inventory to replace .50ANM2. The only heavier cannons were 37mm, but these were by far too heavy. The only real option was adopting 20mm cannon, but there was none such produced in US in early WW2. As the article linked in ImpStarDuece post says, US military in fact wanted 20mm and they bought licence for British Hispano. They wanted it badly enough to get blueprints and example cannons as early as january 1942! Unfortunately some idiot though he knows better than British and altered lenght of chamber. That created problems, which were not solved in time, to let "US Hispano" appear on planes which were entering MASS production in 1942/43. Later it was too late as industry inertia wouldnt permit a change. Not that US 20mm ANM2 was 'cured' entirely before WW2 ended... OTOH .50s were doing good vs. most of small planes. But that doesnt change fact, that 20mms would do better.

    Before I get jumped by 'point-fifty' dedicated fans, I propose to check P-51 (without a letter) with 4 x British Hispanos: there are no bulges on the wings, i.e. Hispano was small enough to fit within P-51 wing. Also I suggest to calculate weights of armament sets, with assumption, a modest one, that single 20mm Hispano is as effective as 3 .50s.

    P-51 B/C entered war with 4 x .50 with 1260 rounds total. That set weight was
    4 x 39kg + 1260rds x 0,112kg = 156 + 141kg = 297 kg

    Now lets replace above with two Hispanos, 50kg each. Further lets keep the weight of entire set unchanged, so
    297kg - 2 x 50kg = 197kg

    We are left with 197kg for ammo. One 20 x 110mm round weight is 0,240kg
    197kg/0,240kg = 820/2 = 410rds

    I.e. each Hispano would have 410rounds! No problem with practical realisation, since that weapon was belt fed, and there would be lots of space after one .50 gun and ammoboxes of both removal.

    P-51B/C had enough .50ammo to fire for 350/13,3 = 26 seconds (although last 5s of that was fire from one pair only, as one of them had 280rds). And imaginary P-51B/C equipped with set of 2 x 20mm Hispanos would fire for 410/10 = 41 seconds! And that is with the same weight as RL plane!

    Lets assume single .50 ANM2 effectiveness is 1, and single Hispano - 3:
    4 x 1 = 4
    2 x 3 = 6, i.e. P-51B/C armament of two 20mm Hispanos would be 1,5 times more effective that RL one with four .50s. Lets also have in mind, that ballistic properties of both weapons were similar - at least similar enough not to make difference within ranges of WW2 aerial shooting, i.e. not further than 300m.

    Who would prefer to fly P-51B/C AND Mustang Mk.III with pair of Hispanos? I definately would!

    That is of course for the sake of comparison, RL Mustang with Hispanos would probably get also a pair of .50s. Assuming that 21s of fire from all guns would be kept, it would be:
    2 x 39kg + 2 x 280 x 0,112kg + 2 x 50kg + 2 x 210 x 0,240kg = 140 + 200 = 340kg

    Only 43kg more than 4 x .50 set with:
    2 x 1 + 2 x 3 = 8 / 4 = 2 - firepower twice greater than of RL P-51 B/C.

    That would not create logistical problems, at least not greater than in case of P-38. All I can say is I wish 20mm cannons were used widely in primary US WW2 fighters
    Share this post

  9. #9
    VW-IceFire's Avatar Senior Member
    Join Date
    Feb 2003
    Posts
    13,650
    Kocur: Just to do a bit of what-if thinking on the Mustang with the 20mm cannons in the wings...while there were no bulges the cannons did stick significantly out of the wing (it looks mean that way ). What if they managed to fit some Hispano Mark V's in there...probably would cover all but a little bit of the barrel...imagine a Mustang with that sort of configuration.

    ...sort of like a Tempest I suppose
    Share this post

  10. #10
    Kocur_'s Avatar Senior Member
    Join Date
    Jun 2005
    Posts
    1,793
    Ah, we can do even more what-if thinking What if replace Hispano with a 42kg 20mm cannon fed with rounds weighting only 0,205/0,183kg...
    Share this post

Page 1 of 9 123 ... Last ►►