Why the early war Japanese fighters were structurally fragile and unarmored?

[FLYBOYJ]

Jiro Horikoshi is my source to confirm the assertion that the Japanese had developed a 'duraluminum' that was purportedly more advanced and lighter in weight than other nation's industries, and was utilized in the Zero fighter. As for it being thinner - I can't confirm that. I have pieces of many Japanese aircraft in my collection, as well as comparable parts of American, German, British, and Russian machines. The thinnest by far seems to have been of Russian origin, but you can also tie the stuff in a knot - almost - it's so malleable. But thicknesses would differ from one panel to another. Japanese wartime metallurgy seems to have been very inconsistent. The only real post-war scientific studies ever conducted, that I know of, were of Japanese steel by the U.S. Navy - specifically steel armor plate in their warships. The results ranged from identifying some of the best steels ever tested - to garbage.

"Duraluminum" is more or less a marketing name for 2024 aluminum. During WW2 it was known at "24T." It is basically aluminum alloyed with copper and has traces of magnesium and manganese in it as well. 2024 or similar alloys were widely used for aircraft skins although I do know that the Soviets used an aluminum similar to 6061.

2024 can be tempered to meet various stress requirements calculated by engineers. The material can go from being extremely malleable but weak in the annealed condition to hard and brittle in some of it's tempered conditions.

2024 was first used in the construction on Zeppelins.

2024 can be made foil thin to rather thick depending on how it's tempered. If I remember there are about 15 different basic temper designations but in today's world you commonly see -O, T-3, T-351 and T-6.

 

[evangilder]

Probably the 64th Kokutai, but I'd have to look it up. 'Hayabusa' is literally Japanese for 'Peregrine Falcon' and, in Japanese vernacular, refers specifically to the Ki-43 series of fighters, or "Oscars". In 1942 that would have been the Ki-43 I with the two-bladed propeller, one of which is preserved in Australia. The Japanese still pay homage to the original WW2 Hayabusa by having named one of their first spacecraft after it, and the world's fastest production motorcycle.

Thanks, the 64th sounds right. I was thinking that before I typed it but wanted to look it up. I had heard rumors of Zeros against the AVG, but I am guessing it was the Oscars they were facing. I haven't seen any evidence to indicate any Zeros at the time. It's an interesting history that I am reading which compares the claims to the actual losses in the records of both the Americans and the Japanese. Both sides overclaimed, although it isn't terribly surprising when you look at the battle as told by different people. That is often the case, two people side by side in the same firefight can have vastly different views by how they took in the information, especially under duress.

 

[ColesAircraft]

Thanks Coles.

You know, I think there's more lack of information in the West than lack of information itself. You see, not today, but in the first decades after the war, there were many veterans and factory workers that were still young and with good memory, I beat they provided this info.

I'm not looking for othing in specific at the momment, I just would like to see what a pilot from a Ki-44 or other still unknow type would tell if asked what color the cockpit was painted. I have some Maru Mechanic books, and I belive the cockpit colors in them were painted according to the veterans, and it's really strange sometimes.

Other question: the Zero and Ki-43 pilots belived their machines were adequate against early war Allied types such as the P-40 and the Wildcat?

Exterior colors for Japanese military aircraft seem to have been usually specified by the military services and did not differ significantly between manufacturers (but not always, early Nakajima-built Zeros were painted a different shade of gray than Mitsubishi-built Zeros, for example), but such was not the case with interior colors.

As a general rule: Japanese aircraft manufacturers outsourced many components to myriad small companies, each using its own paint and colors when painting was required. Thus the landing gear legs of many Japanese fighters were gloss black, including the Zero. Why? That's what the company that made the landing gear used. The same was true of all sorts of components, for the cockpit as well. The only military mandate that effected interior color was the one regarding corrosion prevention, and thus it was required that all aircraft manufactures use Aotake primer to cover all interior aluminum - inside the wings, everywhere. This coating was a clear coat that was mixed with a blue/green tint to make it visible. It served the same purpose as zinc chromate for the Americans, but in tests proved more effective at preventing corrosion. Until later in the war it would be found everywhere, in every aircraft, including crew areas. Many manufacturers, however, painted over the Aotake, and many outsourced parts, with their own paints for crew areas. Mitsubishi did this throughout the war, which is why Zeros and "Bettys", etc., had mat olive green cockpit areas. I've never heard why, but since the Aotake was glossy it might have been a glare concern.

The Ki-44 was a Nakajima product. Since there are no Ki-44s in existence (Except the wings preserved in China - do they have the rest? No one seems to know!) we have to look at other Nakajima-built aircraft for evidence. There are few of them around. I have several cockpit airframe pieces from a B5N2 "Kate" that reveal two different olive greens in use in the cockpit - but alas, this was a rare license-built Aichi airframe! The NASM's J1N1 "Irving" was built by Nakajima and it retains its Aotake primer in the cockpit with all the different colored components. The same seems to be true of Nakajima's Ki-43 "Oscar". Thus it's safe to suppose that the Ki-44's cockpit would be Aotake blue/green, glossy, and filled with lots of different colored parts: probably dark green for radio components, black for the instrument panel, etc.

Hope that helps! It's a long-winded explanation, but the whole subject of Japanese cockpit colors can be a study in itself!


Ron Cole

 

[ColesAircraft]

Thanks, the 64th sounds right. I was thinking that before I typed it but wanted to look it up. I had heard rumors of Zeros against the AVG, but I am guessing it was the Oscars they were facing. I haven't seen any evidence to indicate any Zeros at the time. It's an interesting history that I am reading which compares the claims to the actual losses in the records of both the Americans and the Japanese. Both sides overclaimed, although it isn't terribly surprising when you look at the battle as told by different people. That is often the case, two people side by side in the same firefight can have vastly different views by how they took in the information, especially under duress.

My pleasure! I was actually going to mention the American use of terms like 'Hayabusa' and 'Zero' in my original reply, as in fact they can cause some confusion today. The Allies routinely called any Japanese fighter they encountered a 'Zero' - no matter what it was. I have volumes of USMC 'kill' claims from the war, and among the thousands of encounters listed I think in total there are more 'Zero' losses claimed than there were Zeros actually built. The practice comes out in post-war written accounts as well. If it had one engine and turned like the devil - it was a 'Zero', or sometimes a 'Hayabusa'.

Yeah, eye witness claims can sometimes cause more heartache than they resolve. They've fueled the mildly ridiculous feuds over what color early Zeros were actually painted, for example, as different people heard different information from different vets who swear they flew planes painted everything from chalk white to pale brown. But studying actual aircraft parts for evidence can be just as confounding. I recently obtained these preserved pieces of fuselage from an Fw190A-8 excavation, and from what they reveal this aircraft was painted red, yellow, blue, gray, a bunch of different greens, and black.

?????!!!!!!

 

[ColesAircraft]

Regarding Japanese aircraft construction and cockpit colors, I might suggest checking out the link to a section devoted to the subject on my website:

Japanese Aircraft in Detail JAPACDET

One area is dedicated to some amazing and high quality photos taken during the construction of the N1K1 "George" prototype by the official Kawanishi photographer, detailing each step in the construction process - start to finish. Even disregarding the technical value, it's striking to see the factory workers wearing sandals and tabi socks!

Another area that's unique is a series of photos taken by the Russians of a captured and dismantled A5M "Claude" fighter. Amazing stuff. It's a compilation of the best of most unique photos I've ever found.

 

[FLYBOYJ]

GREAT SITE!

 

[Jenisch]

Interesting.

About the A5M, the Russians regarded the machine has very good, as they also regarded the Ki-27 and it's pilots.

 

[ColesAircraft]

GREAT SITE!

Thank you! Some of the pictures are a little small (now that I revisit it after a time) - I'll try to fix that.

 

[ColesAircraft]

Interesting.

About the A5M, the Russians regarded the machine has very good, as they also regarded the Ki-27 and it's pilots.

The Japanese performed poorly in the Nomonhan Incident with Russia, in which Ki-27s were pitted against Soviet air forces, but not in the realm of air power. The Japanese Air Force in the area was grounded by the Japanese government in Tokyo after they had successfully attacked a Russian airfield, so as to avoid escalating the conflict. That left General Zhukov (later to take Berlin) free to counterattack with overwhelming forces. Nevertheless, the Ki-27 was thought to have performed well.

Russian respect for Japanese air power and pilots came more indirectly from their volunteers in China, who generally speaking were consistently outmatched unless attacking unescorted bomber formations - from which the Navy learned the value of possessing fighters with longer range. The Russians eventually bought several Japanese aircraft captured by the Chinese, including the A5M, Ki-27, and Ki-10. Reports regarding the new Zero were received by all parties involved in the region - but were generally not taken seriously.

 

[evangilder]

Nice! I really like the painting of the captured P-40 with the Zero. The color scheme on the Zero in that painting is very much like the Camarillo Zero.

 

[ColesAircraft]

Nice! I really like the painting of the captured P-40 with the Zero. The color scheme on the Zero in that painting is very much like the Camarillo Zero.

Thank you. I used a picture of that A6M to work from!

 

[evangilder]

I know there are at least a couple of guys that have used that for basis of artwork. The yellow leading edges and the white around the roundels do make for a good looking bird. I had heard about the captured P-40 and it was apparent that they captured a few during the battle of Burma, but that was the first photo I have seen of one.

 

[cherry blossom]

Jiro Horikoshi is my source to confirm the assertion that the Japanese had developed a 'duraluminum' that was purportedly more advanced and lighter in weight than other nation's industries, and was utilized in the Zero fighter. ....

I tried using Google on this and the best hit came up as a thread here five years ago http://www.ww2aircraft.net/forum/aviation/question-about-a6m-duraluminum-9908-2.html which Flyboy should remember as he contributed. Micdrow contributed on Extra-super-duraluminium, ESD, that "The ESD was used on the Zero but not for the skin, It was used for what is usually the most single heaviest member of the structure, The main wing spar." The point was that ESD was stronger but it was subject to corrosion. Other countries rejected it and Japan was alone in using it, rightly as it turned out, because they realised that aircraft would not last long in a war.

 

[FLYBOYJ]

Yep and remember it well. On that link I have all the aluminum temper designations. As stated the ESD probably was closer to 7075. Aluminum and copper alloyed together make a strong structure but is very susceptible to corrosion, that's one of the reasons 2024T skins are usually "alclad" in they have a layer of aluminum over the skin to prevent corrosion.

 

[ColesAircraft]

I tried using Google on this and the best hit came up as a thread here five years ago http://www.ww2aircraft.net/forum/aviation/question-about-a6m-duraluminum-9908-2.html which Flyboy should remember as he contributed. Micdrow contributed on Extra-super-duraluminium, ESD, that "The ESD was used on the Zero but not for the skin, It was used for what is usually the most single heaviest member of the structure, The main wing spar." The point was that ESD was stronger but it was subject to corrosion. Other countries rejected it and Japan was alone in using it, rightly as it turned out, because they realised that aircraft would not last long in a war.

Was that for the wing spar itself, or the spar caps? Spar cap exfoliation is regarded as the big problem with restoring Japanese aircraft - especially Mitsubishi-built machines - for this reason. It infects the Raiden, as we were discussing before in this thread. The wing spars themselves hold up well, but the spar caps (which are cast) corrode quickly into a flaky substance that looks like rotted wood. When it breaks down the internal structure of the wing just falls apart, and the landing gear collapses. But the Germans used a similar alloy as well, though sparingly. I have an original Bf109E instrument panel made of an 'aluminum/magnesium' alloy that shares these attributes.


Ron Cole

 

[FLYBOYJ]

Was that for the wing spar itself, or the spar caps? Spar cap exfoliation is regarded as the big problem with restoring Japanese aircraft - especially Mitsubishi-built machines - for this reason. It infects the Raiden, as we were discussing before in this thread. The wing spars themselves hold up well, but the spar caps (which are cast) corrode quickly into a flaky substance that looks like rotted wood. When it breaks down the internal structure of the wing just falls apart, and the landing gear collapses. But the Germans used a similar alloy as well, though sparingly. I have an original Bf109E instrument panel made of an 'aluminum/magnesium' alloy that shares these attributes.


Ron Cole

The reason why the German material held up better was because they probably controlled the silicon content better as well as keeping other impurities to a minimum. Other factors such as uniform furnace temps and even quench during heat treating play into this as well.

More than likely it was the spar caps that had the problem as this type of structure would usually be constructed out of a 7075 type material with the web of the spar being made from 2024.

 

[drgondog]

Was that for the wing spar itself, or the spar caps? Spar cap exfoliation is regarded as the big problem with restoring Japanese aircraft - especially Mitsubishi-built machines - for this reason. It infects the Raiden, as we were discussing before in this thread. The wing spars themselves hold up well, but the spar caps (which are cast) corrode quickly into a flaky substance that looks like rotted wood. When it breaks down the internal structure of the wing just falls apart, and the landing gear collapses. But the Germans used a similar alloy as well, though sparingly. I have an original Bf109E instrument panel made of an 'aluminum/magnesium' alloy that shares these attributes.


Ron Cole

The Wing Spas (fore and aft) are extruded, not cap and shear web rivet assemblies...

 

[GregP]

Hi Ron Cole,

I talked with the Museum staff this past weekend about the Mitsubishi J2M Raiden and said that when I was finished with the Bell YP-59A we are restoring to flight status, I'd like to take a crack at the Raiden. I spoke both to Ed Maloney (our founder) and to the Board Chairman Byian Boyer. Brian said the Raiden was not on the list at this time because the corrosion is bad enough to warrant full disassenbly and inspection ... and the estimated restoration cost would run between $4M and $5M ... and that was not in the cards at this time.

Ed said the engine is pretty much of a basket case, and that installing an American radial would not do because the engine had really long propeller shaft and American radials don't match that feature ... so we'd pretty much have to resurrect the Japanese raidal, a Mitsubishi MK4R-A Kasei 23a. We MIGHT be able to get Mitsubishi to help ... and maybe not.

So ... probably we'll work on another plane. I'll try for a restoration to flight status of our Ryan Fireball ... we'll see, won't we?

Just FYI.

 

[Jenisch]

Greg, do yous guys that have a Betty? I read it's planned to restore one in the US to flight status.

 

[evangilder]

Greg, I have been waiting for that P-59 to fly and am really looking forward to seeing that. I took some photos of the Fireball on static last year and would like to see that one fly as well. Sounds like you have a lot of work to do on the J2M.