The Kayaba Ku-4 was a research aircraft built in Japan in 1940 to investigate the possibilities of tailless designs. It followed designer Hidemasa Kimura's successful Ku-2 and Ku-3 designs for the Imperial Japanese Army. While these previous aircraft had been gliders, however, the Ku-4 was to be a powered by a pusher engine. It had a low, swept wing, and like the Ku-2, fins at the wingtips.
Work on the prototype was well advanced by April 1941, but the following month, Kimura's relationship with the Army soured following the crash of the Ku-2. The Ku-4 was cancelled, and Kimura eventually received only ¥17,000 of the ¥200,000 that had been promised for the development of his tailless designs.
Specifications (as designed)
- Crew: One pilot
- Length: 3.42 m (11 ft 3 in)
- Wingspan: 9.80 m (32 ft 2 in)
- Wing area: 9.0 m2 (97 ft2)
- Powerplant: 1 × piston engine, 90 kW (120 hp)
- Maximum speed: 180 km/h (110 mph)
- Range: 300 km (190 miles)