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

The story of "Corky" Meyer seeing the Pratt Whitney logo with an eagle and "Quality Reliability" seems to be true. Similarly the picture at 01 three dollar bill G W Bush « Voices from Russia has the words "Federal Reserve Note". However, I do not believe that the Nakajima Sakae has a close relationship with any Pratt Whitney engine. Apart from little details like having different bores and strokes, there is the point that all the valves are driven from in front in the Sakae while P&W two row radials drove the valves of the back row from behind.

On the subject of the A6M needing a Sakae to fly like a Zero, the A6M8 was accepted for production with a Kinsei. However, it did seem to be slower than it should have been which has produced two threads over at J-aircraft Was drag a significant factor in the lack of real performance with the A6M8? and A6M8 performance.

cherry blossom said:

The story of "Corky" Meyer seeing the Pratt Whitney logo with an eagle and "Quality Reliability" seems to be true. Similarly the picture at 01 three dollar bill G W Bush « Voices from Russia has the words "Federal Reserve Note". However, I do not believe that the Nakajima Sakae has a close relationship with any Pratt Whitney engine. Apart from little details like having different bores and strokes, there is the point that all the valves are driven from in front in the Sakae while P&W two row radials drove the valves of the back row from behind.

On the subject of the A6M needing a Sakae to fly like a Zero, the A6M8 was accepted for production with a Kinsei. However, it did seem to be slower than it should have been which has produced two threads over at J-aircraft Was drag a significant factor in the lack of real performance with the A6M8? and A6M8 performance.

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Ah! Good old reliable J-Aircraft.com!

My understanding of the A6M8 is that the aerodynamic efficiency - or lack thereof by mid '40s standards - of the Zero's fuselage design had become an obstacle. The Japanese were perfectly aware of what worked better by the time the A6M8 was in the works, and in fact put such knowledge into the design of the incredibly fast and aerodynamically efficient C6N "Myrt" (the fastest multi-seat single-engine production aircraft of WW2). But the fuselage of the Zero was largely a mirror of its successful predecessor, the A5M "Claude" - which itself was designed in 1934!

The A6M8 had a slightly larger cowling than its predecessor models, but I don't think that counts for drastically increased inefficiency. The firewall behind it remained unchanged. But though it's hard to articulate in words: the Zero's fuselage was tapered in a curve (like a backwards rifle bullet) unlike more modern designs as employed in the C6N, and was not as aerodynamically efficient. Proving that this attributed to the retardation of the A6M8's top speed is probably impossible - but it makes sense as a major culprit. In the end the Zero was never especially fast by WW2 standards. Even the A6M3 fell short of expectations in terms of speed, in spite of clipping its wings, and the D4Y "Judy" that was in service by mid-1942 could walk away from it - and the "Judy" was a dive bomber!


Ron Cole

You might like to hear the story of the planes of Fame A8M5 Model 52 Zero when it went to Japan the first time.

There is no general aviation in Japan. It is all either commercial or military. Today there are a smattering of ultralights, but nothing like we have. Consequently, their airports are not designed like ours and there are no or few windows in hangars, and little way to look out except to open the hangar door. When our Zero was shipped over to Japan, we (the "We" is the Planes of Fame people, I wasn't even a volunteer yet) took it inside a hangar, assembled and test ran it.

When the time came to present it to the crowd, nobody was sure if we'd have any people there, be it 4, 40, 400, or 4000. Nobdoy knew, including the sponsors of the event (flying an authentic Zero over Mount Fuji). When they opend the hangar, there were 1.4 million people out there! Everyone was overwhelmed. We trundled out the Zero, started it, took off and made several passes, then did the photo flight over Mount Fuji. When the Zero returned, about 100 ex-Zero pilots were allowed to sit in the cockpit again for a time, and they came back next day to see it again. It was HUGE hit and everyone had thought the people would be ashamed of the Zero ... but they were very happy to see it, and were especially happy to see it not only run but also fly.

They sang WWII songs when it flew over.

Our Zero has been to Japan twice, and the engines were restored with the help of Nakajima (Fuji Heavy Industries) and Mitsubishi.

Just some info on the Zero ... Cheers!

By estimated data of the A6M8 performance, it doesn't look much different from the N1K2-J.

GregP said:

and Japanese pilots were considered expendable!

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I already read this from an interview with Saburo Sakai. This is funny, since the IJN pilots specially, probably had the hardest selection and training in the world before the war.

Post #64: No, but it was better than the A6M5 ...

Jenisch said:

I already read this from an interview with Saburo Sakai. This is funny, since the IJN pilots specially, probably had the hardest selection and training in the world before the war.

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I don't think they were so much regarded as expendable in the sense that they were not valued as important national assets, they were, as the investment in their training indicated. But the Japanese thought of war in terms of the one war they'd actually fought - and won: the war with Russia in 1904/05. They anticipated a quick decisive battle where attrition played no role, and whatever they had on hand when the war started - in terms of equipment and manpower - would be what they'd win it with. Casualties were expected, but that's what the hard training was meant to minimize, and in the end they believed that their smaller and better trained elite force would overcome whatever was put into its path. Some of the more worldly Japanese elite, such as Isoroku Yamamoto, saw the flaws in this way of thinking - but it was still largely a part of Japanese national identity in the 1930s and '40s.


Ron Cole

Greg, have you ever had a tour bus of Japanese arrived at the POF? We had a couple show up at Camarillo and Steve Barber, who is in a video earlier in this thread took the Camarillo Zero up for the folks to see. It was really something, and they ate it up.

I spent my first few years at Camarillo moving around the Zero that was in two pieces (now at the Pacific Museum on Ford Island) and I was always amazed at how light the tail structure was. We had it on a customer fit dolly and it was no problem for one person to shift it around. There are 2 flyable Zeros in the hangar right now, until later in the spring when the second one will be departing to Alaska. The crew chief on the Camarillo Zero is Japanese and he knows the aircraft quite well. He has corresponded with Mr. Harada on several occasions.

There is something neat about seeing a Zero fly, especially knowing the rarity of them. Regardless of what the performance is with the P&W, they have demonstrated the Zero with the Hellcat on a few occasions and you can clearly see a difference in the turn capability at slow speeds. The "like concrete" statement was something that was told to me by Steve Barber, who has flown the Zero a lot.

With regards to the performance of the A6M8 one needs to look at the pictures of the aircraft and see the differences between the Sakae cowling and the Kinsei cowling.

Posted here: http://www.ww2aircraft.net/forum/flight-test-data/looking-ki-43-hayabusa-data-30779-2.html

One needs to rethink the low altitude performance of the A6M8 with an extra 400 to 500 BHP available.

Mr Cole
Thank you for providing your extensive knowledge on japanese aircrafts
I would like to ask you three qustions
1) I have read somewhere that japanese had very good metelourgy and could built thinner aircraft skins without sacrificing strength, so saving weight. Do you confirm it?
2) Also, many years ago, i have read that in order to save weight , japanese constructed their wings on a single piece or something like that. Do you know anything about that?
3) Japanese used combat flaps in their later fighters apparently with good results. However no other nation used them . Do you have any explanation?
Thank you in advance

jim said:

Mr Cole
Thank you for providing your extensive knowledge on japanese aircrafts
I would like to ask you three qustions
1) I have read somewhere that japanese had very good metelourgy and could built thinner aircraft skins without sacrificing strength, so saving weight. Do you confirm it?
2) Also, many years ago, i have read that in order to save weight , japanese constructed their wings on a single piece or something like that. Do you know anything about that?
3) Japanese used combat flaps in their later fighters apparently with good results. However no other nation used them . Do you have any explanation?
Thank you in advance

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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.

I'm not sure about your second question. Japanese aircraft were uniquely designed to be modular (wings and fuselages could break down into transportable components), but if anything incorporating that feature might have added weight. They did go to great lengths to reduce the number of rivets required in an aircraft design - as was most glaring in the design of the C6N "Myrt", the design of which was detailed extensively in a series run in the 1970s by Koku Fan magazine - to save weight.

The Japanese first used combat flaps in the Ki-43 "Oscar" fighter - first flight tested with combat flaps in 1939. I can't say why (or even if) other nations were less inclined to study this technology - but, again, the Japanese were wedded to the idea of the 'light fighter' and in the pursuit of that goal pushed every envelope to make lightweight and maneuverable aircraft. This was not due to an inability to make powerful engines - as has been asserted. It came from experience in China against other light fighters, such as the I-16. Surely the Japanese would have welcomed a more powerful engine for the Zero in 1939 and later - but not at the expense of weight that would have impacted other 'light fighter' performance priorities. The Raiden proves my point: it was the opposite of the Zero fighter in many ways, yet was designed by Mr. Horikoshi's team almost side-by-side with the Zero (though took much longer to reach prototype stage). The plane was built around its then powerful 1500 bhp (later 1850 bhp) Kasei engine. It's rate of climb was spectacular, it was fast - and, like the Gee Bee racer it vaguely resembled - handled like a truck.*

Thanks for your comments! Japanese aircraft are extremely interesting machines - even for no other reason they they were so different.


Ron Cole


* Incidentally, the Wikipedia page on the Raiden makes it sound like the aircraft was a general flop. Not true. It was regarded by American pilots, encountering the type over the Philippines, as a fearsome opponent that spoiled their developed tactics - referring to it as a "super Zero" - and were quick to warn fellow pilots of it. Notorious Japanese ace pilot Sadaaki Akamatsu loved the aircraft, and boasted that his favorite "prey" was the P-51 - several of which he shot down while at the controls of his Raiden (Though his claims tended to increase with his consumption of alcohol). But few Japanese pilots knew how to play to its strengths, trying to fly it like it was the Zero that most had flown previously. Saburo Sakai test flew the plane and disliked it - but not as much as he disliked the later N1K2 "George" - which he claimed was "a second rate plane from a second rate company".

The Japanese weren't the only ones to have combat or manuvering flaps. The P-38 had a specific setting for it and other aircraft could do the same , if they had adjustable flaps that could be deployed at speed, by just dropping a few degrees of flap.

But most allied pilots , if they were thinking, would not attempt to out turn most Japanese fighters.

Here's a frame from an old Japanese comic strip that I stumbled across that alludes to the whole 'powerful engine/light fighter' issue. I think it humorously speaks for itself:



Ron Cole

Coles, a modeler's question: since you have talked with many Japanese veterans, you already ask them if they remember the colors of aircraft in which there's no data or evidence avaliable?

Mr Cole
Thanks for your respond.
I find strange the comments about Raiden. A member of this forum has uploaded a comparison test between J2M and F6F5 . Raiden using combat flaps appeared to be generaly more manouverable on that test report
It appears that the requeste for manouverability was strong even in 1945. According to wiki A7M2 prototype had ...152 kgr/m2 wingloading ( from 30m2 wing area!) plus combat flaps. Even Yak 3 had 181 kgr/m2!
Or Ki84 . While considered more balanced desigh than the previus japanese fighters , with a loaded weight of 3616 kgr was much lighter than western fighters of its time. On paper has extremely good power and wing loadings. Much better even than F8F. But how such a low weight was possible? 800kgr lighter than an Fw 190A8 !! And Ki 84 had larger wing area!

Jenisch said:

Coles, a modeler's question: since you have talked with many Japanese veterans, you already ask them if they remember the colors of aircraft in which there's no data or evidence avaliable?

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Actually, yes. Believe it or not, among Japanese aircraft 'experts', the subject of what these aircraft were painted arouses furious debate - the most toxic being the rage around what shade of gray early Zeros were painted. But I digress. I've always asked color questions, as a modeler myself. The problem is in interpretation and memory, as I've gotten some pretty strange replies sometimes.

In recent years, though, a whole wealth of new information has surfaced regarding Japanese aircraft colors - inside and out. An original Japanese Navy color specification book was unearthed in Japan, including large paint samples for most everything that the Navy specified for the different manufacturers. More surviving Japanese aircraft, and aircraft pieces, have been discovered in the world, and documented - especially in China and Indonesia.

What information are you specifically looking for?


Ron Cole

jim said:

Mr Cole
Thanks for your respond.
I find strange the comments about Raiden. A member of this forum has uploaded a comparison test between J2M and F6F5 . Raiden using combat flaps appeared to be generaly more manouverable on that test report
It appears that the requeste for manouverability was strong even in 1945. According to wiki A7M2 prototype had ...152 kgr/m2 wingloading ( from 30m2 wing area!) plus combat flaps. Even Yak 3 had 181 kgr/m2!
Or Ki84 . While considered more balanced desigh than the previus japanese fighters , with a loaded weight of 3616 kgr was much lighter than western fighters of its time. On paper has extremely good power and wing loadings. Much better even than F8F. But how such a low weight was possible? 800kgr lighter than an Fw 190A8 !! And Ki 84 had larger wing area!

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The Zero and the Ki-61 "Tony" were the only Japanese fighters not to employ 'butterfly' or combat flaps - but that didn't make the Raiden into an effective dog fighter. No doubt they helped, but the impressions remembered by pilots of the type were not favorable to the Raiden's maneuverability. Maybe Akamatsu would have proffered a different first-hand opinion, but he died in 1984.

The Raiden's maneuverability problem was fundamental: it boasted a gigantic engine on a small fuselage with small wings. It was a Gee Bee with cannon and armor plate. Maneuverability wasn't ignored by its designers, but it wasn't a priority over rate of climb.


Ron Cole

Ok, I do have one question. I am reading about the Flying Tigers and they are encountering "Hayabusas" in the battle for Burma. I am trying to figure out which aircraft they are talking about with Hayabusas. They said they were retractable gear fighters. I will have to dig a little in the previous chapter to see what Kokutai they were in.

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?

evangilder said:

Ok, I do have one question. I am reading about the Flying Tigers and they are encountering "Hayabusas" in the battle for Burma. I am trying to figure out which aircraft they are talking about with Hayabusas. They said they were retractable gear fighters. I will have to dig a little in the previous chapter to see what Kokutai they were in.

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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.