Kayaba Ka-1

The Kayaba Ka-1 was a Japanese autogyro, seeing service during World War II.

Design and development
The Imperial Japanese Army developed the Ka-1 autogyro for reconnaissance, artillery-spotting, and anti-submarine uses. The Ka-1 was based on an American design, the Kellett KD-1A, which had been imported to Japan in 1939, but which was damaged beyond repair shortly after arrival. The Kayaba Industry was then asked by the Army First to develop a similar machine, and the first prototype was flying on 26 May 1941. The craft was initially developed for use as an observation platform and for artillery spotting duties. The Japanese Army liked the craft's short take-off span, and its low maintenance requirements. The production began in 1941 and the first autogyros were assigned to artillery units for artillery spotting. These carried two crewmen: a pilot and a spotter.

Later, the Japanese Army commissioned a small aircraft carrier, Akitsu Maru, intended for coastal antisubmarine (ASW) duties. The Ka-1 was modified by eliminating the spotter's position in order to carry one small depth charge. The carrier was later sunk by American submarines on November 15, 1944.

The prototype, Ka-1 was essentially the repaired Kellett KD-1A. The Ka-1 had a change of the engine to the 240 hp Argus As 10c. But only about 20 Ka-1 were made. The Ka-1 employed similar aspects to the Focke-Wulf Fw 61, which was first flown in 1936.

The production of the remainder were all Ka-2. The Ka-2 returned to the same Jacobs L-4MA-7 engine as the Kellett KD-1. Total Ka-1 and Ka-2 production was approximately 240.