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Japanese Secret Projects of WW2 Vol 1

Amongst many areas, I have been eager to do a profile set of Japanese Secret Project aircraft for some time but the finding and collecting of data and references has proved a somewhat slow process. Japanese secret projects seem to be far less well documented than say German stuff.

I did learn the Japanese used a wide range of colours, markings and camouflage patterns. Camouflage styles covered segment, blotch, mottle, cross hatch, wave and palm leaf types plus schemes of a single colour or two colours. And it seems, as was the case with German WW2 schemes, application could be infinitely varied due to field applied schemes in many instances. But unfortunately the vast majority of pictorial references are usually of green and light grey painted aircraft with an occasional offering of solid brown over light grey or natural metal. Another complication is the fact that Imperial Japan had two distinct air forces; the Army Air Force and that of the Navy, each commanding unique aircraft design, development and production.

I eventually arrived at a point where I felt comfortable enough to start, although I still cannot fully vouch for the authenticity or accuracy of the profile aircraft's’ colour usage, schemes or markings, so I will claim “artistic license” or “Luft 46” rules apply. However should anyone spot something really out of place or obviously wrong please contact me.

The Japanese showed little or no interest in the jet engine or jet powered aircraft until quite late in the war and it is also thought the Germans did not share any data or information from their Me262 programme until the twin jet fighter was actually deployed for active service. Only then did the Japanese pursue the design and development of jet aircraft and jet engines to power them, as by then Allied aircraft had become very much improved and were a real threat to the Japanese planes they opposed.

The aircraft
Kayaba Katsuodori

Very late in the war, German research data was much more forthcoming enabling the Japanese to explore many, to them, new possibilities, such as the use of simple aircraft design that used non-strategic materials and newer forms of propulsion such as the pulse jet and the ram jet.

One such design that was influenced by such new data was the ram jet Kaybaya. It was an all Japanese design with easy construction in mind, using non-strategic materials, such as wood for the wings. Take off was to be by the German dolly method as used by the Me163 and powered by four jettisonable solid-fuel rockets, until level flight had been achieved were the ramjet would have been started. The Kaybaya was a private venture with neither the Army or Navy having any direct influence.

Mansyu Ki-98

Mansyu produced this advanced design to no apparent specification directive. It was an attempt to produce a more effective ground attack platform. The design featured a twin boom layout and a pusher engine/prop allowing a solid nose to accommodate the armaments. The problem of pilot escape seems not to have been dealt with.

Mitsubishi J4M1 Senden (Lightning Flash)

Mitsubishi produced the twin boom Senden design in answer to the Navy specification 17-Shi, sometime in 1943. Not a lot of details are readily available but this version was to be powered by the company’s MK9D engine driving a 4-blade pusher prop. There are some reference drawings that show the 5-blade prop that I included on the profiles. Unfortunately the J4M1 was passed over in favour of the Kyushu J7M1 Shinden, so no further work was continued. There was a second version that I hope to include in a future set.

One small point of interest was the Allies thought this aircraft existed and in readiness of it being a possible combatant it was given the code name “Luke”.

Nakajima Kikka (Orange Blossom)

The first and only Japanese jet aircraft to actually fly during World War 2 was the Nakajima Kikka. In September 1944 the Japanese Naval Staff issued a directive, ordering Nakajima to design and produce a twin-jet engine attack aircraft based on the Messerschmitt Me 262.

Kazuo Ohno and Kenichi Matsumura produced the Kikka design which looked very similar to the German design, but the two aircraft shared not a single part. The Kikka was a little thicker in the cord of the rear fuselage and the engines were mounted much further forward under the wings.

The first engines that were tried on the Kikka were a pair of Tsu-11 ducted flow units but producing only 441 lbs thrust each , proved woefully weak. These were quickly replaced by two Ne-12 turbojets, each producing 750 lbs thrust, a big improvement but still considered underpowered. Finally after examining a number of photographs of the German BMW 003 engine, and to their credit, the Japanese engineers produced a third engine, the Ne-20, producing a much more satisfactory 1,047 lbs thrust each. The design included folding wings not for carrier deployment, but for easy storage in land based underground bunkers. The end of the war curtailed any further development.

Yokosuka RY2 Kieun (Beautiful Cloud)

This aircraft design had a quite long and varied life taking in many types of power plant and influences. In its original form, R2Y1, it used a pair of tandem mounted engines driving a front propeller via an extended shaft based on the German Heinkel He119.

The Germans sold the manufacturing rights and two He119 prototypes to the Japanese in 1940. Development continued with R2Y1 looking very similar to the Me 509.

The R2Y1 was lost due to American bombing and any further development seemed to be over. However a proposal to use jet power for the R2Y saw the project revitalized, materializing in a number of design variants of the R2Y2, attack bomber. The first version proposed mounting the engines under the wings similarly to the German Me 262 and adopting a solid nose. One saw two side by side jet engines mounted in the rear fuselage, with wing root intakes and a solid nose, while a third design featured a nose intake instead.

If you want to read more information on these and many more Japanese Secret Project Aircraft you may like to visit the Hikoki1946 section of www.j-aircraft.org/xplanes/

Until next time...
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About the Author

About Peter Allen (flitzer)

Greetings to all. My real name is Peter Allen and I have recently returned to UK from working in Riyadh, Saudi Arabia, as a creative director in an advertising agency. My home town is Wigan in the north of England. I’m married to Emily, a Polish lass who tolerates my modelling well. I’ve wor...


Great work as always. Really interesting as I had no knowledge about the Japanese "luft46" versions and projects. One thing puzzles me: where is the armament on the Kayaba Katsuodori. It is listed as having two 30mm cannons, but I cannot see where they are placed on the interceptor? I would guess they would be on the side of the fuselage, but I see no openings for the gun barrels? You should collect all the art work and text in a small book and publish it. I think it would sell quite good. Thanks for sharing and kept up your good work!
MAR 14, 2007 - 04:27 PM
Many thanks to Rowan (Merlin) for doing all the hard graft in getting it up on site. And Jesper, you are absolutely right. The armament should be as you say, on the fuselage sides, either side of the cockpit. I guess I forgot to cut a couple of holes... Moreon the way. Cheers Peter :-)
MAR 14, 2007 - 05:11 PM
Hi Peter Let me know when you've got the beast fully armed and I'll replace the pics. All the best Rowan
MAR 14, 2007 - 06:29 PM
Thanks Rowan... I'll add a couple of gun ports and get them off to you. Cheers Peter :-)
MAR 16, 2007 - 11:34 AM
Hi Peter! I've replaced the pics. It's funny how so little can make so much difference! Thanks for sharing these profiles. I didn't knew the Japs had secret projects! :-) Jean-luc
MAR 16, 2007 - 03:31 PM
Many thanks Jean-Luc now that's what I call service.... Cheers Peter :-)
MAR 16, 2007 - 08:37 PM
Great to see those paper projects come to life Peter! The Ki-98 has long been a favorite of mine since first seeing it as a drawing in Rene Francillon's Japanese Aircraft of WW 2 a Putnam publication that was the first comprehensive overview of Japanese aviation. I could be picky and mention that some of the JNAF aircraft have JAAF colour schemes and markings; then again, the two rival organisations did actually share some aircraft types by the end of the war, so I won't quibble too much.
MAR 17, 2007 - 09:27 AM
They look really good Pete, you really need to lay off that Cherry Blossom Wine. :-)
MAR 17, 2007 - 01:09 PM
Many thanks... Dave May be you are right...there's always Fruit cup... Jeff Now if I could get hold of some pukka Sake...I may be able to tell the difference... or you could point out which is which please...for future reference :-) Thanks again Cheers Peter...hic... :-)
MAR 18, 2007 - 07:21 PM