Kawasaki Ki-78

Japanese experimental high-speed aircraft

Ki-78

Role	High speed research aircraft Type of aircraft
National origin	Japan
Manufacturer	Kawasaki Kokuki Kogyo K.K.
Design group	Aeronautical Research Institute of the University of Tokyo
First flight	26 December 1942^[1]
Number built	1 completed + 1x mock-up and the partially complete 2nd prototype^[1]

The Kawasaki Ki-78, originally given the designation Ken III (Kensan - research III), was a high-speed research aircraft (after research projects of long-range and high-altitude aircraft),^[2] also intended to attempt breaking the world absolute speed record.^[1]

Design and development

The Kawasaki Ki-78 was a high-speed research aircraft developed to investigate laminar profile wings with high wing loadings. Early in 1938 a high-speed research program was started at the Aeronautical Research Institute of the University of Tokyo for a small single-seat aircraft.^[1]

The Ki-78 was designed at the Aeronautical Research Institute and built at Kawasaki Kokuki Kogyo K.K. to investigate flying behaviour at very high speed. It featured a streamlined minimum cross-section fuselage fitted with a licence-built Daimler-Benz DB 601A engine. For short durations, power boost methanol/water injection was used and cooling was improved by a 45 kW (60 hp) turbine driven cooling fan for the radiators.^[1]

All-metal construction was used in combination with a small thin wing with a laminar flow profile and a sharp leading edge.^[1]

Operational history

By the outbreak of the war, the whole project was taken over by the Imperial Japanese Army who gave it the military type designation Ki-78. Kawasaki received the order to build two prototypes of the Ki-78, construction of which was started in September 1941. The first was completed more than a year later and was flown for the first time on 26 December 1942. A feasibility study to improve the KI-78 flight performance showed that extensive airframe modifications were needed and consequently the project was officially terminated after the 32nd flight on 11 January 1944; the second Ki-78 was never completed.^[1]

Specifications (Ken III / Ki-78)

Data from Japanese Aircraft of the Pacific War^[1]

General characteristics

Crew: 1
Length: 8.1 m (26 ft 7 in)
Wingspan: 8 m (26 ft 3 in)
Height: 3.07 m (10 ft 1 in)
Wing area: 11 m² (120 sq ft)
Empty weight: 1,930 kg (4,255 lb)
Gross weight: 2,300 kg (5,071 lb)
Powerplant: 1 × Daimler-Benz DB 601A V-12 inverted liquid-cooled piston engine rated at 1,160 kW (1,550 hp) with Water/Methanol injection for short durations

Performance

Maximum speed: 700 km/h (430 mph, 380 kn) at 3,500 m (11,500 ft)
Range: 600 km (370 mi, 320 nmi)
Service ceiling: 8,000 m (26,000 ft)
Wing loading: 209 kg/m² (43 lb/sq ft)
Power/mass: 0.373 kW/kg (0.2273 hp/lb)

References

^ ^a ^b ^c ^d ^e ^f ^g ^h Francillon, Rene (1979). Japanese Aircraft of the Pacific War. London: Putnam & Company Limited. ISBN 0-370-30251-6.
^ スピード追い求めた幻の翼研三 - KENSAN -. かかみがはら航空宇宙科学博物館. p. 10.