Nakajima G10N - Design and Development

Design and Development

The Fugaku had its origins in "Project Z", a 1942 Imperial Japanese Army specification for an intercontinental bomber which could take off from the Kuril Islands, bomb the continental United States, then continue onward to land in German-occupied France. Once there, it would be refitted and make another return sortie.

Project Z called for three variations on the airframe: heavy bomber, transport (capable of carrying 300 troops), and a gunship armed with 40 downward-firing machine guns in the fuselage for intense ground attacks at the rate of 6,400 rounds per second.

While the project was conceived by Nakajima head Chikuhei Nakajima, Kawanishi and Mitsubishi also made proposals for the Fugaku. The Nakajima design had straight wings and contra-rotating four-blade propellers; the Kawanishi design had elliptical wings and single four-blade propellers. To save weight, some of the landing gear was to be jettisoned after takeoff (being unnecessary on landing with an empty bombload), as had been planned on some late-war German very long range bomber designs. Both designs used six engines.

Development started in January 1943, with a design and manufacturing facility built in Mitaka, Tokyo. While Nakajima's 4-row 36-cylinder 5,000 hp Ha-54 (Ha-505) engine was abandoned as too complex, Mitsubishi successfully built the 2-row 22-cylinder Ha-50 engine for the Kawanishi design, testing three units in May 1944. An example of this engine was unearthed in 1979 during expansion of Haneda Airport and is on display at the Narita Aerospace Museum.

Project Z was cancelled in July 1944, and the Fugaku was never built.