Aviation of World War II

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Experimental High-speed Fighter


Ki-78 Ken III (Kensan III) is an experimental high-speed aircraft designed to study the properties of a laminar wing at high wing loads. In early 1938, a high-speed research program for a small single-seat aircraft was launched at the Institute of Aviation Research, University of Tokyo.

To achieve record speed, an all-metal construction was used in combination with a small, thin wing with a laminar flow profile and a sharp leading edge. The aircraft used a streamlined fuselage with a minimal midship. To reduce the landing speed and improve controllability at low flight speeds, the wing was equipped with hovering ailerons and a combination of slotted flaps and Fowler flaps, which was used for the first time on Japanese aircraft.

A licensed Daimler-Benz DB 601A engine was installed as a power plant. For a short-term increase in power, injection of a water-methanol mixture was used, and the cooling of the radiator was enhanced by a fan driven by a turbine, taken for cooling power of 45 kW (60 hp).

Kawasaki Ki-78
Crew 1
Wing span, m 8.00
Wing area, m² 11.00
Length, m 8.47
Height, m 8.10
1 × PE Daimler-Benz DB-601А, power, hp 1 × 1175
with injection of water-methanol mixture 1 × 1550
Weight, kg:
Empty weight 1,930
Gross weight 2,300
Maximum speed, km/h 700
Service ceiling, m 8,000
Service range, km 600

The first flight of the Ki-78 took place on December 26, 1942, during which poor controllability at low flight speeds and extremely low stall characteristics were discovered. The aircraft turned out to be heavier than in the design and estimate documentation, which increased the already high specific wing loading. Even with special flaps, takeoff and landing speeds remained high and reached 205 km / h and 170 km / h, respectively. In addition, at a relatively low speed of 635 km / h, elevator flutter was detected, to eliminate it, horn compensation was installed on the rudders.

Flight speed tests began in April 1943, and in the 31st flight, December 27, Ki-78 at an altitude of 3527 m developed a maximum speed of 699.6 km/h, which was significantly less than the expected speed of 850 km / h. Research has shown that significant modifications to the airframe were necessary to improve the Ki-78's flight characteristics, and as a result, after the thirty-second flight, on January 11, 1944, the Ki-78 test program was officially terminated. The second Ki-78 was never completed.

Photo Description
Drawing Ki-78

Drawing Ki-78


  • Record aircraft Kawasaki Ki-78 / Ivan Byakin /
  • Japan Aviation. / Andrey Firsov /
  • Encyclopedia of Military Equipment / Aerospace Publising /

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Ki-78 destruction

Ki-78 survived the war, but did not arouse interests of the Americans and in 1945 it was destroyed at the Gifu factory airfield.