Question about A6M Duraluminum? - Aircraft of World War II

Gibbage · 10-16-2007, 08:05 PM

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?

FLYBOYJ · 10-16-2007, 08:17 PM

Quote:

Originally Posted by Gibbage

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?

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.

drgondog · 10-16-2007, 08:21 PM

Quote:

Originally Posted by Gibbage

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?

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.

Gibbage · 10-16-2007, 08:24 PM

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.

Gibbage · 10-16-2007, 08:29 PM

Quote:

Originally Posted by drgondog

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..

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.

FLYBOYJ · 10-16-2007, 08:32 PM

Quote:

Originally Posted by Gibbage

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.

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.

FLYBOYJ · 10-16-2007, 08:39 PM

I stand corrected on the alloying elements in 2024 - Aluminum and copper - no magnesium...

evangilder · 10-16-2007, 08:43 PM

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.

drgondog · 10-16-2007, 08:44 PM

Quote:

Originally Posted by Gibbage

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.

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?

FLYBOYJ · 10-16-2007, 08:50 PM

Quote:

Originally Posted by drgondog

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?

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....

16KJV11 · 10-16-2007, 08:52 PM

Quote:

Originally Posted by evangilder

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.

That's what I have read also.

evangilder · 10-16-2007, 09:17 PM

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.

Gibbage · 10-16-2007, 09:36 PM

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

FLYBOYJ · 10-16-2007, 09:39 PM

Quote:

Originally Posted by Gibbage

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

No.....

evangilder · 10-16-2007, 09:48 PM

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.

10-16-2007, 08:05 PM	#1
Gibbage Junior Member Join Date: Dec 2006 Posts: 24	Question about A6M Duraluminum? 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?

10-16-2007, 08:39 PM	#7
FLYBOYJ IP/Mech THE GREAT GAZOO Join Date: Apr 2005 Location: Colorado, USA Posts: 16,877	I stand corrected on the alloying elements in 2024 - Aluminum and copper - no magnesium... __________________ > I Support Doug Gillis <

10-16-2007, 08:43 PM	#8
evangilder "Shooter" Join Date: Sep 2004 Location: Moorpark, CA Posts: 15,421	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. __________________ For once you have tasted flight you will walk the earth with your eyes turned skywards, for there you have been and there you will long to return. Leonardo Da Vinci

10-16-2007, 09:17 PM	#12
evangilder "Shooter" Join Date: Sep 2004 Location: Moorpark, CA Posts: 15,421	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. __________________ For once you have tasted flight you will walk the earth with your eyes turned skywards, for there you have been and there you will long to return. Leonardo Da Vinci

10-16-2007, 09:48 PM	#15
evangilder "Shooter" Join Date: Sep 2004 Location: Moorpark, CA Posts: 15,421	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. __________________ For once you have tasted flight you will walk the earth with your eyes turned skywards, for there you have been and there you will long to return. Leonardo Da Vinci

10-16-2007, 08:24 PM	#4
Gibbage Junior Member Join Date: Dec 2006 Posts: 24	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.

10-16-2007, 09:36 PM	#13
Gibbage Junior Member Join Date: Dec 2006 Posts: 24	My question really is not if they were easy to shoot down, but if there was magnesium in the skin.

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