Kayaba “Ka”-Go / Ka-1 / Ka-2
In 1939 the Imperial Japanese Army imported a Kellet KD-1A single-engined two-seat autogyro as an artillery spotter. Powered by a 225hp Jacobs L-4M4 seven-cylinder air-cooled radial, the KD-1A featured an advanced version of the Kellet direct control rotor system. Shortly after its arrival in Japan, the aircraft was seriously damaged during flight trials at low speeds. The Kellet KD-1A had been damaged beyond repair, but the Japanese Army delivered the wreck to K.K. Kayaba Seisakusho (Kayaba Industrial Co Ltd), a small company doing autogyro research, with instructions to develop a similar machine.
The Kayaba engineering team developed a two-seat observation autogyro based on the Kellet KD-1A but modified to Japanese production standards, designated Ka-1.
The Ka-1 was powered by a 240hp Kobe eight-cylinder inverted-vee air-cooled (licence version of the German Argus Argus As 10c) engine driving a two-blade propeller, and had a three-blade rotor. Completed in May 1941 at the Sendai (Miyagi Prefecture) plant of Kayaba, the first Ka-1 made its maiden flight at Tamagawa on 26 May, 1941.
During its flight test programme the Ka-1 performed remarkably well, demonstrating its ability to take-off after running only 30m in still air. By running the engine at full power and holding the nose 15 deg up, the Ka-1 could hover and could also execute a full 360 deg turn while hovering. As maintenance in the field appeared to present less difficulty than anticipated the aircraft was placed in production for service with artillery units.
Eventually some two hundred and forty aircraft of this type were built.
A small number of Ka-ls were modified for operation from naval craft as anti-submarine patrol aircraft. As the load-carrying capability of the standard two-seat Ka-1 was too limited, the carrier-borne Ka-ls were operated as single-seaters and carried two 60kg bombs or depth-charges. In this role the Ka-ls operated over Japanese coastal waters and particularly over the Tsugara and Korean channels.
The Kayaba Ka-1 autogyro was the first armed autogyro/helicopter to have been used operationally.
At least one of these aircraft, the Ka-1 KAI, was tested with powder rockets on the rotor tips in an attempt to improve its load-carrying capability while another aircraft was fitted with a 240hp Jacobs L-4MA-7 seven-cylinder air-cooled radial. With Jacobs engine the type became the Ka-2.
Engine: 1 x Kobe/Argus As 10c, 180kW / 240 hp
Main rotor diameter: 12.2m
Max take-off weight: 1170kg
Empty weight: 775kg
Max speed: 165km/h
Cruising speed: 115km/h
Armament: 2 x 60kg depth charges