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Kawanishi K-90/KX-2 "Jinpu" (J3K, J6K & carrier-based A8K)

CherryBlossom

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Hello everyone,

It was discussed some time before on this topic, but was wondering if anyone found out more about the Kawanshi A8K1 Toppu?

It seems that there was speculation on whether this was indeed a real project and/if it was a carrier-based J6K.

Does anyone have any information or resources to prove its existence and what it was?

Thanks

Cherry
 

blackkite

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Oh Toppu(突風)!! This is the first time for me to see this name. :eek:

突風 means
•a (sudden) gust of wind
or
•a squall
or
•a blast of wind

I find this site.
https://forum.valka.cz/category/view/500610/Kawanisi
 

CherryBlossom

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blackkite said:
Oh Toppu(突風)!! This is the first time for me to see this name. :eek:

突風 means
•a (sudden) gust of wind
or
•a squall
or
•a blast of wind

I find this site.
https://forum.valka.cz/category/view/500610/Kawanisi
Hi blackkite,

Is it a genuine aircraft? There was discussion about its existence and was wondering if this was true

Cherry
 

airman

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http://japaneseaircraftofwwii.blogspot.it/2015/03/kawanishi-a8k-projected-fighter-carrier.html

where Mitsubishi A8M seems be A7M3 for carriers .

Nakajima A8N it's new for me
 

blackkite

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CherryBlossom said:
blackkite said:
Oh Toppu(突風)!! This is the first time for me to see this name. :eek:

突風 means
•a (sudden) gust of wind
or
•a squall
or
•a blast of wind

I find this site.
https://forum.valka.cz/category/view/500610/Kawanisi
Hi blackkite,

Is it a genuine aircraft? There was discussion about its existence and was wondering if this was true

Cherry
Sorry I'm not sure. Why was there discussion about Toppu existence? Any evidence? Who said the existence of Toppu?
I have not seen Toppu information in Japanese sources.
 

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probably because carrier-based Kawanishi J6K was J6K1-A instead A8K !?
 

blackkite

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Ummm......What is the difference between J6K and A8K?

http://forum.valka.cz/topic/view/86276/Kawanisi-A8K1-Toppu
https://forum.worldofwarships.ru/topic/32334-kawanishi-a8k/
https://www.facebook.com/Bruyneel.Patrick/photos/pb.1665620223655805.-2207520000.1476345766./1747193092165184/?type=3
"Kawanishi A8K Toppu 1945 (Japan). Embarked Hunter.
The Kawanishi A8K was a development of the j6k Jinpu, a terrestrial interceptor that had not been retained. It was then modified to be used as an on-board fighter on the Japanese aircraft door to replace the famous zero. It had a folding canopy, was fitted with a NK9H Nakajima Homae 21 1990 CV radial engine. The aircraft was heavily armed and carried
Four 30 mm wing cannons. The prototype was finished at 95% when the war was over."

But no carrier at the day. :-[ Looks like fake?
 

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CherryBlossom

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blackkite said:
Ummm......What is the difference between J6K and A8K?

http://forum.valka.cz/topic/view/86276/Kawanisi-A8K1-Toppu
https://forum.worldofwarships.ru/topic/32334-kawanishi-a8k/
https://www.facebook.com/Bruyneel.Patrick/photos/pb.1665620223655805.-2207520000.1476345766./1747193092165184/?type=3
"Kawanishi A8K Toppu 1945 (Japan). Embarked Hunter.
The Kawanishi A8K was a development of the j6k Jinpu, a terrestrial interceptor that had not been retained. It was then modified to be used as an on-board fighter on the Japanese aircraft door to replace the famous zero. It had a folding canopy, was fitted with a NK9H Nakajima Homae 21 1990 CV radial engine. The aircraft was heavily armed and carried
Four 30 mm wing cannons. The prototype was finished at 95% when the war was over."

But no carrier at the day. :-[ Looks like fake?
That is a shame, at least there is further clarity on the issue.
 

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If carrier-based A8K was a fake must be mentioned like fictional in some sources ??? ???
 

blackkite

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Yes anyway we need evidence. ;)
I think it's true that there are no evidence for Toppu existence.
 

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blackkite said:
Yes anyway we need evidence. ;)
I think it's true that there are no evidence for Toppu existence.
So could be that carrier-based A8K haven't an officially code ::)
 

blackkite

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Jinpu(陣風) was cancelled in 8th of July 1944.
In 1th of may 1945 there was a meeting between the IJN,IJA and aircraft makers.
In this meeting, there was a discussion about high altitude air superiority fighter(甲戦) development(開発). (Land base fighter.)
Candidates were as follows.
(1)Shiden-kai or Reppu parts utilization plan.
(2)Jinpu base plan.
(3)New design.
And Jinpu base plan did not selected.

Source : "Reppu and Reppu-kai", Gakken, ISBN4-05-602990-3, page168-171.

"The (Toppu)prototype was finished at 95% when the war was over." ← Apparently fake. No Kawanishi engineer said so.

There was a Jinpu development story(開発始末) by famous Yoshiro Ikari(碇義朗) based on Kawanishi engineer Reiji Toyofuku(豊福厲治)'s diary in Maru magazine.(June 1993 page 122-129.) I can't find any description about Toppu. ;)

https://www.google.co.jp/search?q=%E7%A2%87%E7%BE%A9%E6%9C%97&source=lnms&tbm=isch&sa=X&ved=0ahUKEwiyrbnU8bDVAhWKfLwKHQ0-AiMQ_AUIBigB&biw=1366&bih=617
 

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blackkite

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To understand Jinpu is very hard for me,too.
You can see the caption of this picture at the right side bottom of this picture.
J-6-33/32
19-6-1.

19-6-1 means "the first day of June 1944". It was just the before day of the IJN'S J6K wooden mochup first inspection day.
It's true that Kawanishi received the IJN's first inspection by this wooden mockup as J6K. So it's natural to think that this was J6K.
Engine nacelle side air intake might be intercooler cooling air intake. But I can't find intercooler air outlet which must be located side of the fuselage.
Because I imagine this mockup was a almost J3K mockup with MK9B engine. Engine nacell side air intake was for Vulkan coupling drive supercharger.
The IJN inspector claimed this fact and ordered mockup modification.  

And Jinpu cancelletion was told to the factory at the eighth of July 1944.
 

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blackkite

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This picture was taken at 15th and 9th of July 1944. (after cancellation)
I think J6K final design also had engine nacelle side air intakes sama as J3K.
Also I think J6K had intercooler air outlet which must be located side of the fuselage.
These are only my poor opinion which must be corrected.
 

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blackkite

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Amazing drawings as usual my brilliant Justo-san!!:cool:
There are many many mysteries to be solved about WWⅡJapanese military aircraft still now.;)
 

blackkite

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I compare Matsuba-san's Jinpu and Shiden-kai front view (almost same scale).
Jinpu's engine was Nakajima Homare, NK9A-O(Ha45-42), two stage two speed mechanical supercharger with intercooler and forced cooling fan.
Shiden-kai's engine was Nakajima Homare, NK9H, single stage two speed mechanical supercharger.
Both engine diameter were same.(1,180mm)
Shiden-kai's engine ram air intake and oil cooler air intake were located front end of the engine nacelle.
Ram air intake was located top of the engine nacelle and oil cooler air intake was located bottom of the engine nacelle.
Jinpu's engine nacelle was very slim compared with Shiden-kai. It was very hard to have ram air intake behind the forced cooling fan.
Perhaps Jinpu's ram air intake and oil cooler air intake were located outside of the engine nacelle bottom.(Little small size?)
I can't find intercooler air intake in this front view drawing.
 

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blackkite

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You can see Tachikawa Ki94Ⅱ's two intercooler air intakes located under the wing.
The engine was a Nakajima Ha-44. Ha-44 was a powerful 2,400hp class engine.
I want to say that intercooler air intake size is not small.
 

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blackkite

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Shiden-kai's main landing gear tires were retracted under the fuselage.
But Jinpu's main landing gear tires were not retracted under the fuselage.
I think that this means Jinpu's engine ram air intake interfered main landing gear tires when tires retracted under the fuselage.
Narrow main landing gear tread is desirable to realize small moment of inertia around directional axis.
But Jinpu was a high altitude interceptor for B-29 attack, not a air superiority fighter. Jinpu's designer selected high speed performance.

I imagine that Jinpu's first stage mechanical supercharger was a twin blade type which located both side of the fuselage bottom.
Twin intercoolers were located over the first stage supercharger.


 
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