Nakajima G10N Fugaku
The Nakajima Fugaku ("Mount Fuji") was a planned Japanese ultra-long-range heavy bomber of the Second World War, designed under Project Z to take off from the Kuril Islands, bomb the United States and fly on to land in German-occupied France. Conceived by Chikuhei Nakajima around six projected 5,000 hp engines, it was cancelled in July 1944 before construction began: no prototype was built, nothing survives, and every performance figure published for it is a design projection.
Why It Mattered
The Fugaku was Japan's bid for a true intercontinental bomber: it was to take off from the Kuril Islands, bomb the contiguous United States, and then fly on across the Atlantic to land in German-occupied France, refuel and rearm there, and repeat the sortie in reverse. It grew out of Project Z, a 1942 Imperial Japanese Army project to design a bomber capable of reaching North America, and it was conceived by Chikuhei Nakajima, head of the Nakajima Aircraft Company. Its published data promised a range of 19,400 km (12,055 miles) with a bomb load of 20,000 kg, at a projected speed of 779 km/h (484 mph). The project was cancelled in July 1944 and the Fugaku was never built, so its significance is as a statement of intent: the mission Japan wanted an aircraft to fly.
Design Notes
The design had straight wings and six engines, driving contra-rotating four-blade propellers. Each engine was to be a Ha-54 of 5,000 hp: two 18-cylinder Ha-44 engines mounted in tandem in each nacelle, making a 36-cylinder, four-row powerplant. To save weight, some of the landing gear was to be jettisoned after takeoff, as it would not be needed for a landing made with the bomb load gone. All of its figures are projections from the design data: a maximum speed of 779 km/h (484 mph) at 10,000 m, a range of 19,400 km (12,055 miles), and a bomb load of 20,000 kg (44,092 lb). Project Z also called for transport and gunship versions of the airframe: a transport capable of carrying 300 troops, and a gunship with forty downward-firing machine guns in the fuselage. Design arguments over ceiling and defensive armament were settled in favour of the Navy's requirement for 15,000 m (49,200 ft), with light armament accepted in view of the low interception risks.
Operational History
There is no operational history: the Fugaku never flew, no prototype was completed, and no service ever operated it. Project Z began with a 1942 Imperial Japanese Army specification for an intercontinental bomber, and Nakajima initiated development in January 1943, building a design and manufacturing facility at Mitaka, Tokyo. Despite its Army origin, the programme was a joint Army–Navy project. Designs from other firms were presented under the same programme, including Kawasaki's Ki-91, which reached only scale-model form, and a Kawanishi flying-boat conversion that remained a concept; of the Project Z designs, none but the G5N Shinzan even reached prototype form, and the Fugaku remained a project only. The engine programme failed first: Nakajima's 36-cylinder Ha-54 was abandoned as too complex, after the tandem arrangement's cooling problems proved insurmountable, and the design reverted to a 2,500 hp engine that halved the power available. With the fall of Saipan the project was terminated, and Project Z was cancelled in July 1944.
Afterlife
Nothing physical survives: no prototype was ever built, so there is no airframe to preserve, restore or display. The programme's own documentation was supposedly burned when the project ended, which is why published reconstructions of the design rest on postwar compilations, such as the performance data printed from Edwin Dyer's Japanese Secret Projects. A 1956 Japanese three-view drawing of the type drew on data from Nakajima designers Tei Koyama and Katsuji Nakamura, and later drawings differ from it in detail. Even the type's usual name is a postwar convenience: the G10N designation is an extrapolation from the Japanese naming system, and reference works warn that it is sometimes still used incorrectly.