Did the U.S. attempt to design a different aircraft gun?

Discussion in 'Aviation' started by DAVIDICUS, Apr 23, 2005.

  1. DAVIDICUS

    DAVIDICUS Member

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    I thought I read somewhere that the U.S. had designed or at least flirted with the idea of designing a new gun for use on aircraft. I think it was a .60 cal. or something like that.

    Is there anything to this or is my dimentia acting up again?
     
  2. DAVIDICUS

    DAVIDICUS Member

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    OK, here's something. It was the T17 and was 15.2mm x 114mm. (The .50 BMG was 12.7mm x 99mm)

    Does anyone know what the performance specifications were for this cartridge?

    From http://www.quarry.nildram.co.uk/MilRel.htm

    In 1939 the US Army issued a requirement for an anti-tank rifle capable of penetrating 1ΒΌ" (32mm) of armour at 500 yards (460m). This produced the massive .60" cartridge. The rifle never saw service, neither did the T17 aircraft machine gun (developed from captured Luftwaffe MG151) which was intended to use it. Different designs of .60" machine guns (including revolver and rotary versions) were experimented with but without success.

    In the constant USAAF search for higher velocity the cartridge was also necked down to .50", generating up to 4,400 fps (1,340 m/s) with lightweight incendiary bullets. None of the HMGs came to anything and the cartridges are merely collectors' items.

    Ironically the Americans learned the same lesson as the Germans had with the MG151 and necked up the case to form the 20mm M39 round which has been the standard USAF cannon cartridge since the 1950s. Its most famous application is in the six-barrelled rotary M61 Vulcan cannon, which also serves as the business end of the Phalanx anti-missile system.
     
  3. Anonymous

    Anonymous Guest

    As you've pointed out the T17 was played with but never came to anything.

    And of course there was the M1, AN-M2, and finnally M3 versions of the Hispano 20mm. The M1 and many of the AN-M2's suffered from a defect in the chamber clearances making them unreliable. Even in its British form the gun was never more than about 1/3rd as reliable as the .50 BMG.

    For the most part, the USA felt the .50 BMG was sufficent for the task of killing fighters and Japanese bombers, and it clearly was when arrayed in groups of 6-8.

    I do have to wonder why the US did not neck up the BMG to 20mm like the Japanese did with the Ho-5 (a BMG derivative). Seems rather obvious to me.

    =S=

    Lunatic
     
  4. Matt308

    Matt308 Glock Perfection
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    Does this answer David's query? I have also read about a taperbore gun that was played with too. Interesting concept the taperbore.
     
  5. DAVIDICUS

    DAVIDICUS Member

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    What was it?
     
  6. Matt308

    Matt308 Glock Perfection
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    A cannon that by its definition tapered from breech to muzzle. The tapering increased muzzle velocity into the 4500+ ft/sec realm. Originally developed by the Germans (I believe) for armour piercing capability in small caliber rifle/cannon, caliber of weapon eventually increased up to 75mm. I do recall reading that some experimentation was made with aircraft armament by the US.

    As an example, I remember reading about the projectile originally designed with skirts to allow for the tungsten projective to squeeze down the bore while still trapping the propellant and thus an increasing pressure vs friction curve. To get an idea of the degree of tapering, I think I recall the 28mm cannon tapering down to 20mm at the muzzle. Use of tungsten is the precursor of the depleted uranium rounds we now read so much about. I think tungsten is basically the same material as that of the M1A1 APFSDS round.

    Interesting principle that can still be found today in some modern rifles using wildcat cartridges. Must be expensive to manufacture though. Probably why it was not a embraced on a large scale. I would love to have someone tell me which form of rifling (button, cut, hammer forged, etc) is used for a taperbore. Better yet, I would like to see the mechanics of the machinery that does it!
     
  7. DAVIDICUS

    DAVIDICUS Member

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    Interesting.

    What modern wildcat catridges employ a tapered bore?
     
  8. Matt308

    Matt308 Glock Perfection
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    I knew you were going to ask that. I'll have to check my gun rags to see if I can find the references. I read about wildcats, don't shoot 'em.

    I did find that a German by the name of Gherlich invented the principle in the 1920s. Apparently more than just the Germans were fiddling around with this idea. Hotchkiss was even working with the French on a taperbore cannon. Most applications that I have ever read about were for anti-tank and anti-aircraft artillery.

    I have also read about modern rifle makers using a micro-taperbore. Probably just an adjunct to a true taperbore that tapers ~30% of bore diameter.

    ...now the other experiment might have been gain twist rifling. But that's another story.:D
     
  9. DAVIDICUS

    DAVIDICUS Member

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    I have dabbled a bit in wildcatting. It's a very expensive and time consuming hobby. I have a .30-.378 Weatherby which I played around with before I got married. The thrill of high velocity shoulder launched cannons no longer has an appeal to me. .338 Winchester is about the most recoil I can tolerate these days.

    My favorite wildcat at present is the .338/06. I had one made on a Mauser action with a Douglas barrel. It's a good shooter. Perfect for hogs.
     
  10. Matt308

    Matt308 Glock Perfection
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    It's been a while since I reloaded...or shot extensively for that matter. I'm set up to load 9mm, .223, .308, .380ACP, .45ACP, .30-06 and .357Mag. I can relate how wildcatting would be VERY time consuming.

    Speaking of hogs, did you see in the paper that some forensic experts dug of "Hogzilla" and confirmed its existence? Apparently, the ranch owner finally let them in to dig it up. They claim there is another couple that same size running around on the ranch. Jeez. I would hope that a hog that big is just fat and docile...and not mean as hell like I have seen exhibited by some of the smaller ones. The experts cocluded that the hog indeed was not 9 feet long and 1000lbs. Rather, they said it was over 8ft long and over 800lbs. Holy crap!
     

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  11. DAVIDICUS

    DAVIDICUS Member

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    National Geographic did an episode on it. They think that a really big domestic pig escaped and mated with a large wild hog. It had a ready food source as a result of living around a fish farm where it ate fish feed.

    800lbs with 9" tusks (they were curled around almost in a circle). That's a monster!

    How is the pig hunting in Washington?
     
  12. Anonymous

    Anonymous Guest

    Squeeze bores have some significant advantages, but they require very strong alloys and precise ammunition tollerances. Also, the bore cannot be rifled, which diminishes accuracy a bit.

    There is some argument about the validity of the squeeze bore concept, especially amoung the brits.

    As far as I know, this was never considered for an aircraft gun in WWII (or since even...).

    =S=

    Lunatic
     
  13. Matt308

    Matt308 Glock Perfection
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    Interesting, RG. I could have sworn that I heard of US experiments in taperbores for aircraft. I know that tungsten was a rare commodity for Germany with its virtual landlocked trading capability. I have not read the tolerances were of issue. The ammunition or projectile by definition was loose in tolerances to accomodate a 30% reduction in bore diameter from breech to muzzle. The skirts were what accomodated the taper.

    We can contemplate the usefulness of taperbores, but to this day they are still used in some form for either accuracy or increased velocity in rifle calibers. For cannons, smooth bores with discarding sabots are the legacy.

    Hog hunting in WA? None to my knowledge unless they are on private ranches. To get Hogzilla size creatures, I would want your .30-.378 WM.
     
  14. Anonymous

    Anonymous Guest

    It's not the tollerance of the actual projectile that needs to be good, it's the tolerance of the whole round in order for it to feed properly.
     
  15. Matt308

    Matt308 Glock Perfection
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    Huh? Not sure what you mean with respect to a taperbore weapon.
     
  16. Anonymous

    Anonymous Guest

    On a tank gun it does not matter, but on high RoF belt fed weapons the flanges on the rounds would have to be aligned properly to feed properly.
     
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