Question about A6M Duraluminum?

Discussion in 'Aviation' started by Gibbage, Oct 16, 2007.

  1. Gibbage

    Gibbage New Member

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    For years, I heard that one of the reasons why the Zero was so flammable was a high concentration of magnesium in the aluminum alloy they used. It was VERY light, but made the metal brittle and flammable. Does anyone know the mixture they used for the alloy? VS the mixture in most US WWII aluminum? Also, how thick was the skin of the A6M vs US aircraft?
     
  2. FLYBOYJ

    FLYBOYJ "THE GREAT GAZOO"
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    The aluminum used on the Zero was very similar, if not the same as 24T or in todays world 2024 T3 or T6. I don't believe Magnesium was part of the alloy, zinc seems to be the major alloying element. In the old threads we have a very lengthy discussion about this, I even took pictures of various WW2 aircraft skins for a comparison. If I remember right the Zero's skin ranged from about .030 to .060. Us aircraft was from .030 to .125 depending on the aircraft and the loaction on the skin.
     
  3. drgondog

    drgondog Well-Known Member

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    Most wing skins in US aircraft were .032 to .040 - with exceptions when the torque box required more as well as some larger flush rivet requirements. Dimpling is usually required for .032 and .040 will usually take a countersink with at least 1.5 edge distance, 2.0 pereferably.

    It would require an Extraordinary concentration of magnesium for the Aluminum ally to be 'flammable' per se... w/o knowing all the facts I would give most of the credit to lack of armor plating for fuel cells..

    I just looked up T3, T4 and T5 - all have exactly the same Mag constituency --> 1.2-1.8 percent. So if the Jap Zero was a flamer so was the Hellcat

    I would doubt that the wing skin varied much from US as the primary purpose of skin was to take shear out of spars and ribs when they were under bending loads.
     
  4. Gibbage

    Gibbage New Member

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    Im VERY sure that magnesium was a part of the A6M's alloy. You can find a few sources on the net about it. Later on, the US made a few aircraft made of just magnesium. The B-29's cylinder heads, XP-56 prototype, and B-36. So its not unheard of.
     
  5. Gibbage

    Gibbage New Member

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    Aluminum itself is flammable under the correct conditions, and adding magnesium lowers its burn temp a lot. From what I recall, tracer rounds could set the A6M's wings alight due to its high heat, and the magnesium would keep the flame alive even in 300MPH wings. Add fuel, and or fuel vapor, and you have a very bad situation for the pilot.
     
  6. FLYBOYJ

    FLYBOYJ "THE GREAT GAZOO"
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    Magnesium was used in some areas but was not part of the aluminum alloying. Brake caliper castings and some other parts were probably magnesium but 90% of the airframe was aluminum.
     
  7. FLYBOYJ

    FLYBOYJ "THE GREAT GAZOO"
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    I stand corrected on the alloying elements in 2024 - Aluminum and copper - no magnesium...
     
  8. evangilder

    evangilder "Shooter"
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    The reason the wings would burst into flames with a tracer round is simple, no self sealing fuel tanks. There is practically no armor in the Zero either. Once a tracer round hits avgas, you have a torch.
     
  9. drgondog

    drgondog Well-Known Member

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    Gibbage - I don't doubt that a magnesium alloyed aluminum would more easily sustain a local ignition due to API or Incindiery - but would you really pose that as more of a reason for a flamer as a couple of hits in an unprotected fuel tank?

    Alclad 'back in the day' was 2024-T3,T4 and T6 - I will dig in the old material properties to see what I can see but doubt I will find much verification for you.

    I designed around a lot of 2024 and 7075 plus some 6063 and 64 when welding was important but don't recall any high mag properties for those?
     
  10. FLYBOYJ

    FLYBOYJ "THE GREAT GAZOO"
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    2024 - Aluminum and .20% copper by weight T3 - solution heat treated, T-4 solution heat treated and artificially aged. T-6 solution heat treated and then cold worked....

    These are off the top of my head but I think I might be pretty close....
     
  11. 16KJV11

    16KJV11 Member

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    That's what I have read also.
     
  12. evangilder

    evangilder "Shooter"
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    There are plenty of gun cam clips that show it. There are also a number of pilots who shot them down who will tell you that you only need a short burst on the wing and the flames will take care of the rest.
     
  13. Gibbage

    Gibbage New Member

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    My question really is not if they were easy to shoot down, but if there was magnesium in the skin.
     
  14. FLYBOYJ

    FLYBOYJ "THE GREAT GAZOO"
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    No.....
     
  15. evangilder

    evangilder "Shooter"
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    You asked if the reason the Zero was so flammable because of magnesium in the skin. The question was answered and then some.

    No aircraft was made completely of magnesium. Magnesium parts, like wheels, yes, but the entire aircraft, no.
     
  16. drgondog

    drgondog Well-Known Member

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    The answer is yes... as there was in both 2024 and 7075 aluminum skins in american and German aircraft - although I'm not sure how much 7075 was used at all in WWII.

    7075 is the EXTREME of aluminum sheet with 2.0-2.8 % by composition - a full percent above 2024-T4 and it was Not Flammable!

    So the answer to you fundamental question is No. Japanes Zero nor Betty nor Dinah nor George had 'flammable' wing skins- at least not any more than F6F, P-40 or SBD's (or Me 109s or Spits or Yaks)

    As Joe pointed out a Turbo on a B-17, while a magnesium fiorging, was also an alloy and even though it was at least 40% by weight it wasn't particularly flammable - it's not like we are talking Willy Peter 4.2 shells!
     
  17. FLYBOYJ

    FLYBOYJ "THE GREAT GAZOO"
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    The XP-56 was made from Magnesium - that's all she wrote!
     
  18. FLYBOYJ

    FLYBOYJ "THE GREAT GAZOO"
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    Here we go - 1.2 - 1.8% Mg in 2024 - hardly enough to strike a match!
     

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  19. Gibbage

    Gibbage New Member

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    The B-36 also.
     
  20. Gibbage

    Gibbage New Member

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    OK. Im doing a lot of research on this topic. I think a lot of you guys are assuming that the Japanese used standard aircraft aluminum. What they did use was something called Extra-Super Duraluminum (Or ESD) produced by the Japanese company of Sumitomo Metals.

    Here is what I found about ESD so far.

    "The development of wrought aluminum alloys in Japan about transportations, mainly, airplanes, railway cars, motor cycles and automobiles are summarized. In airplanes, especially fighters before World War II, higher strength aluminum alloys were required to compete with European or American fighters. ESD (Extra Super Duralumin), which strength was higher than duralumin or super duralumin, was invented and applied to Zero Fighter. This alloy was modified as 7075 in USA during WW II."

    Anyone have the values of ESD? Im not comming up with anything solid on ESD other then it was used in the A6M.
     
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