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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...