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Kawasaki Ki-91 long range heavy bomber

blackkite

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Hi! I believe this is a trace of original drawing. This drawing is from Kawasaki designer Takeo Doi's book.
50 years memory of aircrafts design by Takeo Doi, Kantosha, ISBN4-87357-014-X C0053 P2890E
 

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PlanesPictures

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Thank you very much. Every iteration of drawing has "ïmprovements" of its new author and therefore I prefer original drawings although in poor quality. As sample I attach drawing of Dornier P252-2. Red lines is some new clear improved drawing. But some parts are totally out
 

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lark

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In my humble opinion,the windtunnel model of the Ki-91 forms
a solid basis also as background for drawings...
 

blackkite

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Hmmm...
blackkite said:
Hi! Kawasaki Ki-91 long range heavy bomber
Length : 33.35 m
Height : 10.00 m
Span : 48.00 m
Wing area : 224.0 m²
Aspect ratio : 10.3
Wing cross section : Laminar flow wing
Empty weight : 34,000 kg

Gross weight : 58,000 kg
Maximum speed : 570 km/h (at 10,000 m)
Service ceiling : 13,500 m
Time climb to 8,000 m: 20minutes 30seconds
Range : 9,000 km(with 4ton bomb)
Over 10,000km(without bomb)
Engine : Mitsubishi HA214Ru turbo charged air cooling radial 18cylinders(2,500 hp × 4)
Propeller : constant speed, 4 blades, diameter 4.4 m
Fuel :27,500ℓ(the wing contained almost fuel)
Crews : 8
Armaments : 20 mm cannon × 9、Bomb : 8,000 kg(max)


The line which connect inner and outer propeller spinner top in the 3 side view is parallel to the wing leading edge line, but the wind tunnel test model's same line is not parallel to the wing leading edge line.

http://matever.com/archives/ct01complete/_91_1144.html
 

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Jemiba

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blackkite said:
The line which connect inner and outer propeller spinner top in the 3 side view is parallel to the wing leading edge line, but the wind tunnel test model's same line is not parallel to the wing leading edge line.
Well spotted, blackite ! And comparing modeland drawing, there ae other differences, too, although some of them
may be caused by the photo of the model not being a precise plan view, although it sems to be. To be fair, the
draughtsman may have used other sources, too (or even other models ?), which may show some details diferently.
But I agree to lark, that the most authentic source probably is the wind tunnel model.
 

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PlanesPictures

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Yes, it is my way in similar case, too. Wind tunnel model as base and to check useful details on other sources. 3D modeling is as spy job. Plus you have to find compromise between not absolutely precise top/side/front views
 

blackkite

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Many thanks my dear Jens and Jozef. :D There were some differences between wind test model and most reliable three side view drawing. ???
Hmmm...Mystery.
 

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Did we have all clear similar with Fugaku versions? I wanted to render it but I had problems to collect right sources
 

Stargazer2006

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I'm not sure the question is so much whether one is more "authentic" than the other. Both the plans and the wind-tunnel model originate from the company.


It's just that there can be variants in the plans, but not many wind-tunnel models. The tunnel stage is usually an indication that the design has attained its most developed form and is ready for tests.
 

Jemiba

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What I meant with "authentic" in this context, was just, that although we see those
typical "old fashioned" blueprints, we shouldn't be too sure, that they don't just stem
from the fund of requisits made for the TV drama (for example !) mentioned by blackkite !
About wind tunnel models, there often is a stage in the development, where a lot of different
models are used, for determining the best basic configuarion, just remember our Junkers EF/
EFo thread. How many models were used to find out the final layout for the Ju 287 ?
When this stage is finished, the model in most cases remains unchanged, because the details,
that often need changes for during all those teething troubles (fillets for fins and wings for example)
probably were too small to be tested in the wind tunnel with reliable results, I think.
Unfortunately, in the case of the Fugaku there seem no models to have survived. Maybe for the
mentioned early stage there just was no need, becus of the quite conventional layout ?
 

blackkite

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PlanesPictures said:
Did we have all clear similar with Fugaku versions? I wanted to render it but I had problems to collect right sources
Hi! It's clear that we can't find survived official drawing for final Fugaku shape which determined by all Japan Fugaku comittee(member : the IJA, the IJN, Nakajima, Mitsubishi, Kawanishi, etc) still now. So it's impossible to render reliable final Fugaku shape.(I believe that final Fugaku had a slanting cocoon type pressurized cabin( B-29 like wind shield), turbo charged eigines, remote controlled turrets and dropable main tires.)
But I believe that we get reliable Fugaku candidate official drawing recently. I think it's better to construct 3D image for this candidate.
 

windswords

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CherryBlossum,

If you don't mind me answering, that is a G8N. As far as I know they did not ever make the Ki-91, so it was just a "paper project".
 

blackkite

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windswords said:
CherryBlossum,

If you don't mind me answering, that is a G8N. As far as I know they did not ever make the Ki-91, so it was just a "paper project".
Yes I think so,too. ;)
 

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windswords said:
CherryBlossum,

If you don't mind me answering, that is a G8N. As far as I know they did not ever make the Ki-91, so it was just a "paper project".
Thanks for your reply Wind,

I have looked at different sources they state the Ki-91 began construction but was never finished. Some proof of the partial construction is something i would be interested in.

Do you know what sources say it was a paper project?
 

windswords

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No not really. Just that I've never seen a picture of a prototype or even a partial construction. According to Ed Dyer's book Japanese Secret Projects a wood mockup was made and inspected by the JAAF in May 1944. The book also says that construction of a prototype was began but the factory was bombed by the Americans in February 1945 which severely damaged the project. With the war situation worsening the project was abandoned to concentrate on fighters.
 

blackkite

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Japanese wikipedia says that
"Ki-91 full scale mockup inspection by the IJA were held in May and April 1944. The result of the mock up inspection was good. A factory for experimental productions of Ki-91 was completed in June 1944, installation of making jig began after factory completion.
Completion of No.1 experimental aircraft with pressurized cabin was scheduled in June 1946, completion of No.2 experimental aircraft with pressurized cabin was scheduled in March 1947.
But the Japanese mainland bombing by U.S. forces increased the violence from these days, and inevitably, an assembly plant in Gifu for this aircraft also changed the production system because the thing which becomes a target of bombing was expected. But the environment for the development of this aircraft aggravated because of delay of new large power engine with turbo charger, and lack of the fuselage material in particular, the aluminum alloy.
It was obvious by deterioration of the war that it was the situation to concentrate energy on production of interceptor and special attack aircraft than strategic bomber
Development cancellation of this aircraft was considered by the IJA and experimental production cancellation of Ki-91 was dictated in February 1945.
When cancellation, the design had ended until the stage of the 60%.
Further, every materials which Ki-91 need were gathered in experimental production factory in Gifu when cancellation."
 

Stargazer2006

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Thanks a lot for this valuable info, folks, although I do believe it would be put to better use in a dedicated Ki-91 thread...
 

blackkite

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I hope that Ki-91 full scale mockup pictures are still survive somewhere in Japan now and we will see these pictures near future. ;)

http://alternathistory.org.ua/proekt-tyazhelogo-bombardirovshchika-91-kawasaki-ki-91-yaponiya
 

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windswords said:
No not really. Just that I've never seen a picture of a prototype or even a partial construction. According to Ed Dyer's book Japanese Secret Projects a wood mockup was made and inspected by the JAAF in May 1944. The book also says that construction of a prototype was began but the factory was bombed by the Americans in February 1945 which severely damaged the project. With the war situation worsening the project was abandoned to concentrate on fighters.
I have the book as well, its a dam shame about it.

It reminds me of the Ki-98 and Ki-119, I just wish to see some photos of them!

But otherwise i have another question; The Ki-91 was supposed to have 12 x 20 mm cannons according to various sources. However, In artist impressions and the drawings, you find it difficult to see where the remaining two go. I think if i recall correctly, the far-rear turret housed 4, but again i cannot see them on the impressions/drawings. Do you know why this is?
 

blackkite

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Hi!
I think 20mm cannon were 10.
Some Japanese source says that each fuselage side had a 20mm cannon.
But I can't confirm it.

http://military.sakura.ne.jp/ac/ki91.htm

武装(armament) 20ミリ機関砲(20mm cannon)×12(連装銃座(coaxial machine cannon)(機首(nose)、前方下部(front under)、上部(upper)、後方下部(aft direction under)、尾部(tail))5、
胴体側面左右各1(fuselage left and right side had one cannon each))、爆弾(bomb)4,000kg~8,000kg搭載
 

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blackkite said:
http://military.sakura.ne.jp/ac/ki91.htm

武装(armament) 20ミリ機関砲(20mm cannon)×12(連装銃座(coaxial machine cannon)(機首(nose)、前方下部(front under)、上部(upper)、後方下部(aft direction under)、尾部(tail))5、
胴体側面左右各1(fuselage left and right side had one cannon each))、爆弾(bomb)4,000kg~8,000kg搭載
In "The Xplanes of Imperial Japanese Army & Navy 1924-45" the armament is listed as 20mm x12 but in the drawing there are only x10. :-\
 

blackkite

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Hi!
The engine was Mitsubishi Ha214 ru(HA42-21 ru or MK10 or A18) with turbo charger.
This engine has 4 kinds of name in the thing which should be marvellous. Crazy! ;D
Take off power was 2,500hp each.
RU means turbo charged engine.
Ha214's base was the Kasei 14 cylinders air cooling engine.
Ha214 was a 18 cylinders air cooling engine.
Ki-91 engine nacelle shape is very clean same as Mitsubishi Hiryu's engine nacelle.
We can't see ram air intake for engine and air intake for oil cooler.
Perhaps Ha214-ru engine had a forced cooling fan.
Perhaps Ki-91's engine was same as Mitsubishi 4-shiki heavy bomber Hiryu Ki-67-Ⅱ's engine.

Of course A18 engine had many delivatives for example, A18A,B,C,D,E.
(1) Single stage two speed mechanical supercharger type ; A18A?
(2) First stage turbo charger+second stage two speed mechanical supercharger type ; A18B?(Ha214 ru?)
(3) Single stage three speed mechanical supercharger type ; A18C?
(4) Vulkan coupling drive first stage supercharger+second stage two speed mechanical super charger type(for pusher) ; A18D?
(5) Vulkan coupling drive first stage supercharger+second stage two speed mechanical super charger type(for tractor) ; A18E?
 

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blackkite

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TerryM76

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Saipan B-29 base received several Japanese aircraft attack. And some B-29 were destroyed without Ki-91.
Japanese aircraft which attack Saipan B-29 base were the IJA's Mitsubishi type 97 bomber(97式重爆撃機), the IJN's Mitsubishi type 1 bomber(一式陸上攻撃機) and Mitsubishi Zero fighter(零式艦上戦闘機) from Iou island(硫黄島). They were all Mitsubishi's aircrafts. ;)
Wish I had noticed this part ot the thread a few years ago. Do you know when the last Japanese air attack occurred on Saipan B29 base? My father was stationed on Saipan during last year of the war. One of his duties was guarding the fresh water supply. He passed last year and he often spoke about his time on Saipan but made no mention of any air attcks.
 

blackkite

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The first japanese attack on Saipan Island was completed on November 2, 1944, when nine Japanese Army Air Corps heavy bombers were launched and three were unreturned, but there was no damage to the U.S. military. In addition, the Japanese Luk army and the Japanese Navy jointly attacked the airfield in Saipan as a retaliatory attack on November 27, three days after Tokyo's first air raid. Two four-type heavy bombers of the Second Independent Squadron, led by Major Norinori Shinkai of the Japan Army Air Corps, bombed Isley Airfield (renamed by the U.S. Army than athletes), and the battle results were damaged by four aircraft, and both type 4 heavy bombers were brought back alive. Next, 12 Zero Fighter steams of the first shield corps led by lieutenant Kenji Omura of the Japan Navy Air Corps, machine-gun shot five B-29 swept through Isley Airfield, and also shot down one of the P-47 that had intercepted, but m Zero Fighter was all unreturned. Major Shinkai's second independent squadron also destroyed four B-29s in a night attack on December 7, damaging 23 aircraft. The last attack was at Christmas in 1944, when he first sprayed a tin-foiled imitation paper (electric probe, now a chaff), deceptiond radar, and then attacked Saipan and Tenian with a clever attack of simultaneous entry of high and low, defeating four B-29s, 11 aircraft are damaged. The Japanese army's attack on an airbase in the Mariana Islands completely destroyed or wrecked 19 B-29aircraft, damaging 35 aircraft, and 245 U.S. military casualties.
 

TerryM76

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Thank you for the response. If I recall correctly, my father did not arrive on Saipan until after January 1945. I need to research his military service history further.
 

blackkite

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Perhaps your father was a very lucky man same as my father.
Those were small but brave counterattack by Japanese aircraft.
 

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