Nakajima Kikka - Design and Development

Design and Development

After the Japanese military attaché in Germany witnessed trials of the Messerschmitt Me 262 in 1944, the Imperial Japanese Navy issued a request to Nakajima to develop a similar aircraft to be used as a fast attack bomber. Among the specifications for the design were the requirements that it should be able to be built largely by unskilled labor, and that the wings should be foldable. This latter feature was to enable the aircraft to be hidden in caves and tunnels around Japan as the Navy began to prepare for the defense of the home islands. Nakajima designers Kazuo Ohno and Kenichi Matsumura laid out an aircraft that bore a strong but superficial resemblance to the Me 262.

The Kikka was designed in preliminary form to use the Tsu-11, a very crude thermojet style of jet engine that was little more than a ducted fan with an afterburner. Subsequent designs were planned around the Ne-10 (TR-10) centrifugal-flow turbojet, and the Ne-12, which added a four-stage axial compressor to the front of the Ne-10. Tests of this powerplant soon revealed that it would not produce anywhere near the power required to propel the aircraft, and the project was temporarily stalled. It was then decided to produce a new axial flow turbojet based on the German BMW 003.

Development of the engine was troublesome, based on little more than photographs and a cut-away drawing; but a suitable unit, the Ishikawajima Ne-20, was finally built. By summer 1945, the Kikka project was making progress once again and at this stage, reflecting the deteriorating war situation, it is possible that the Navy considered employing the Kikka as a kamikaze weapon although the prospect was questionable due to the high cost and complexity associated with contemporary turbojet engines. As well, other more economical projects meant specifically for the role such as the simple Nakajima Tōka (designed to absorb Japanese stock of obsolete engines), the pulsejet-powered Kawanishi Baika, and the infamous Yokosuka Ohka, were either underway or already in mass production.

Compared to the Me 262, the Kikka airframe was noticeably smaller and more conventional in design, with straight (rather than swept) wings and tail surfaces. The triangular fuselage cross section characteristic of the German design was less pronounced, due to smaller fuel tanks. The main landing gear of the Kikka were taken from the A6M Zero and the nose wheel from the tail of a Yokosuka P1Y bomber.