Effect of the US produced HS.404R4M 20mm cannon being perfected pre-war?

Discussion in 'Aviation' started by gjs238, Oct 31, 2014.

  1. gjs238

    gjs238 Well-Known Member

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    #1 gjs238, Oct 31, 2014
    Last edited: Oct 31, 2014
    Or at least early war.

    Figure if we can have a thread about the "Effect of the R4M rocket being invented pre-war" we could do the same for US production of the Hispano-Suiza HS.404R4M 20mm cannon - not an unreasonable expectation.
     
  2. stona

    stona Well-Known Member

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    If they could have got the cannon to work reliably then I think we would have seen both Army and Navy fighters armed with it during the war.
    As the .50 calibre M2 Browning proved adequate for the task that US aircraft were expected to perform its limitations, in terms of hitting power, were never really revealed. US aircraft never routinely had to engage formations of heavily armoured bombers like the Germans and Japanese, both of whom adopted ever larger calibre cannon for the task. The British had plumped for the 20mm cannon for much the same reason early in the war. For the most part the US fighters were engaging the much more fragile enemy fighters. This in turn meant that there was less urgency to develop reliable cannon armament, so we never saw it.
    Cheers
    Steve
     
  3. Denniss

    Denniss Active Member

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    A reliable cannon would have at least been used in the strafer nose of the various medium bombers so equipped and some fighter-bombers dedicated to ground attacks.
     
  4. tomo pauk

    tomo pauk Creator of Interesting Threads

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    I'm afraid that it would not bring too much. Maybe outfitting the P-39 with it and that's it; early US fighters were already over-burdened by hevy batteries (bar P-38 ).
    Much more benefit would've been achieved with the V-1710 having a bigger supercharger :)
     
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  5. stona

    stona Well-Known Member

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    That would have been a sensible use. The 20mm cannon of the 2nd TAF's Typhoons were by far their most effective weapon.

    Cheers

    Steve
     
  6. gjs238

    gjs238 Well-Known Member

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    Other potential uses for 20mm cannon are antiaircraft batteries, vehicle mounted weapon, boat/ship mounted weapon, etc.
     
  7. Shortround6

    Shortround6 Well-Known Member

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    Just for the record the US spent a tremendous amount of money on heavy machine guns that went nowhere, ie they couldn't get them to work to acceptable level of reliability or durability.

    from Tony Williams website:
    HMG2.jpg

    Cartridges 7,8, 9 and 10 from the left were ALL experimental cartridges worked on in WW II. "15.2x114 (US .60" T17), 12.7x114 (US .50/60"), 12.7x120 (US .50" HV - from 20mm HS.404 case), 16x99 (US 16mm Vega exp)"
    Cartridge #1 is a standard US .50 cal round for scale.
    There were a variety of experimental guns to fire these cartridges.
    The US wanted higher velocity for shorter flight times and increased hit probability (less lead needed). Please note that round #9 is a 20mm Hispano case necked to .50 cal and would need a Hispano cannon with new barrel to fire it (another reason these cartridges/rounds went nowhere, the size/weight of the guns) post war they necked the the 15.2x114 (US .60" T17) case out to 20mm and it became the round used in variety of US 20mm cannon including the Vulcan gun.

    The US was NOT sitting back fat, dumb and happy with the .50 cal. They just went too far down the wrong road.
     
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  8. stona

    stona Well-Known Member

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    They were happy enough with the performance of their .50 calibre machine guns throughout the war. They may have been spending a lot of money and resources on other heavy machine guns, were these intended for use in aircraft?

    What they didn't have was the incentive to really push the development of cannon armament for their fighters (or other aircraft for that matter) as it was demonstrably not necessary given the operations being undertaken. When did the USAAF start to fit cannons as standard armament to its fighters? They might not have been sitting back "fat, dumb and happy" but as far as cannon for their aircraft go they were sitting back.

    Cheers

    Steve
     
  9. gjs238

    gjs238 Well-Known Member

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    SR6 - Great info. Demonstrates that there was apparently some level of dissatisfaction with the .50 BMG.
     
  10. swampyankee

    swampyankee Active Member

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    According to at least AG Williams, the USN's experience showed that the 20 mm was about 3 times as effective as the 0.5 in. Its shortcoming seemed to be the result of poor construction practices by the US ordnance industry, possibly because of a rather arbitrary division between "artillery" and "small arms."
     
  11. Garyt

    Garyt Member

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    The Oerlikon 20mm became a fairly standard ship mounted weapon early in the war for the US.

    One thing US fighter might have had with the Hispano as opposed to the .50 cal - Less firing time to put rounds on target :)

    As I'm thinking about it, more firing time but less damage per hit might be more helpful for a beginning to intermediate level pilot. Particularly if they are not going after heavy bombers.

    And I'd definitely rather have 6 guns with 450 rounds each of .50 caliber than 4 hispanos of 60 rounds each like the British Spitfires if I'm shooting at a plane without self sealing fuel tanks.
     
  12. Shortround6

    Shortround6 Well-Known Member

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    They were pursuing the wrong path.

    One reason the US .50 was as successful as it was is because of it's high velocity and well shaped bullet which meant A, a shorter time of flight than any other aircraft rounds except the Hispano, Soviet 12.7mm and German 15mm rounds. And only the 15mm was actually superior. This simplified the aiming problem. The US had a study that estimated that a 25% increase in velocity would result in 50% more hits (on average, and this is before the advent of the MK 14 sight and it's like) )(and would increase damage of a hit but that was secondary) and they went after this with a vengeance despite the cost in large heavy guns, burnt out barrels, weight of ammunition and broken guns.

    You can't damage the enemy aircraft if you don't hit it and they were trying to increase the chances of hitting over the ability to do more damage with each hit.

    This is of course in addition to a number of programs that were trying to increase the rate of fire on the standard Browning .50 cal. which took a number of years and only paid off in 1945, too late to have any real effect.

    Part of the problem may have been to stringent requirements. Initial requirements called for not more than one breakage and 5 stoppages per 5,000 rounds fired.

    High Standard handled the T22 series (7 different models)
    Frigidaire handled the T25 series ( 4 models, the last of which was standardized as the M3)
    High Standard also handled the T27 series (8 models)
    Aberdeen Proving ground handled the T-26 and T-28.

    Other programs came in at the end of the war and post war to boost rate of fire to 1500rpm.

    .60 cal guns
    Bendix modified a 20mm Hispano to take necked down ammuniton to 15mm.
    Colt Started a program to copy the German MG 151 in 15mm except to use the American .60 cal cartridge (originally designed as an anti-tank rifle/MG round) , which required not only rechambering the barrel but lengthening the receiver, the feed way, bolt, cam tube and cover and other minor changes. This program shifted to Frigidaire and went through 5/6 models including both percussion and electric primed.
    BTW max velocity was given as 3696fps (1120m/s).
    There were a few other attempts to modify Hispano cannon to the smaller 15mm (.50 cal) round.
    Work on .60 cal guns continued post war with 6 barreled Gatling guns being chambered for the round. Necking the case out to 20mm essentially resulted in the M61 Vulcan gun.

    There were a rather bewildering array of 20mm gun projects under taken during the war. Including a number of attempts to sycronize the Hispano by various means (no explanations to why), modifying Hhispanos from gas (or partial gas) to recoil operated, modified MG 151s, lightened-high rate of fire versions ( finally standardized as the M3 20mm gun about the end of the war or shortly after) and a others.



    And yes, these guns were intended for aircraft.

    Try : http://photos.imageevent.com/badgerdog/generalstorage/georgemchinnthemachinegun/TheMGV3a.pdf
     
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  13. stona

    stona Well-Known Member

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    That was fine for the USAAF and USN engaging Japanese types and Luftwaffe fighters. It doesn't work when you have to engage heavily armoured bombers. The RAF was well aware that it's eight gun fighters were going to struggle with their rifle calibre machine guns in 1939, not long after they were introduced.
    The arguments for eight guns had been based on calculations of the limited time on target the fighters were likely to have against high speed modern (in the mid 1930s) targets and rate of fire rather than weight of fire had been prioritised. The adoption by the Luftwaffe of relatively light armour started to show the flaw in the argument by 1940 and frantic and initially unsuccessful efforts were made to get a working 20mm cannon installation in the Spitfire. German bombers were returning to their continental bases with dozens or even hundreds of rifle calibre strikes. It wasn't long before a combination of two 20mm cannon and four .303 machine guns became the armament fitted to the vast majority of Spitfires built (some substituted two .50 calibre machine guns for the four .303s). Bigger fighters like the Typhoon and Tempest dispensed with machine guns altogether adopting a four cannon armament.

    Both the Germans and Japanese, confronted with the heavily armoured US bombers adopted ever heavier cannon armament. Even 20mm canon was considered by both inadequate for the task they faced. Late war, some Luftwaffe fighters were abandoning their machine guns in favour of cannon armament, sometimes including a 30mm firing through the spinner. No one ever considered fitting machine guns of any calibre to the Me 262 or Do 335.

    The USN caught up at the end of the war, the USAF (as it was by then)didn't really catch up until Korea.

    Cheers

    Steve
     
  14. tomo pauk

    tomo pauk Creator of Interesting Threads

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    Until the US S/E fighters got the 6 HMG battery with plenty of ammo, RAF's fighters were flying with belt-fed Hispanos.
     
  15. Edgar Brooks

    Edgar Brooks Active Member

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    #15 Edgar Brooks, Nov 1, 2014
    Last edited: Nov 1, 2014
    No Spitfire had only 4 cannon as its sole armament until the Mark 21, in late 1945; once the so-called "universal" wing became standard, from the Vc onward, it could carry 4 cannon + 4 .303" Brownings, though 2 + 4 was more normal.
    Only the Ib, IIb, Vb VI cannon had just 60 rounds of 20mm ammunition, and, even then, they had 4 Brownings as back-up; in the universal set-up it was around 150 rounds per gun.
    Also, if you have enemy bombers, with armour plate impervious to .303" or .5" bullets, roaming over your country, killing friends and family alike, you'd be praying for 20mm cannon to put a stop to it.
     
  16. stona

    stona Well-Known Member

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    Indeed. Being bombed is a wonderful incentive to devise better ways of destroying the bombers and killing their crews.

    The British were aware of the problem well before the war as discussions about cannon armament start to become frequent and serious from about 1936 onwards. The Air Ministry instructed Supermarine to prepare a scheme to mount a 20mm Hispano cannon under each wing of the Spitfire in December 1938, nearly a year before the war started (for us).

    It was Joseph Smith who decided that any cannon installation would have to be internal and though it was far from perfect the initial mock up was fitted to K9791 which was only the fifth production Spitfire.

    Cheers

    Steve
     
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