The Kyushu K10W 'Oak' was an intermediate trainer based on the North American NA-16 and that replaced the Yokosuka K5Y1 in Japanese naval service.
The Japanese aircraft industry had originally developed by copying and improving Western designs, but by the late 1930 it had moved on from that and was creating world class designs of its own. The only exception to this was in the 'K' series of naval trainers, where two of the most important trainers in service during the Pacific War were based on foreign designs, both originally produced in Japan by Kyushu. The first of these was the Kyushu K9W, a basic trainer based on the German Bücher Bü 131 Jungmann. The second was the Kyushu K10W1, which was based on the North American NA-16 basic trainer.
Japanese interest in the NA-16 began in 1937 when Mitsubishi purchased two examples of the aircraft, one powered by a 450hp Pratt & Whitney R-965-9CG engine and one powered by a Wright R-975-E3. Mitsubishi passed the aircraft on to the Japanese navy, which tested them as the KXA1 and KXA2 Navy Experimental Type A Intermediate Trainers. The navy was impressed by the aircraft and decided to purchase a licence to manufacture the aircraft in Japan. Production of the new trainer was entrusted to K.K. Watanabe Tekkosho, and the modified aircraft was designated the Navy Type 2 Intermediate Trainer (K10W1). Watanabe was later renamed Kyushu, and the aircraft is normally referred to as the Kyushu K10W1, although the company letter remained 'W'.
The K10W was a low-wing monoplane, with a crew of two carried in tandem under a greenhouse canopy. The wings had a straight centre section and tapering outer sections, with more of a taper on the leading edge. The vertical tail surfaces differed from those on the NA-16, and the aircraft was given a more powerful 600hp Nakajima Kotobuki 2 Kai air-cooled radial engine.
Watanabe built 26 K10W1s, before in November 1942 production was transferred to Nippon Hikoki, which built 150 aircraft between February 1943 and March 1944 (the aircraft was thus actually never built by the renamed Kyushu Company). The K10W1 replaced the earlier K5Y1 as the standard intermediate trainer in the Japanese Navy, although by the time it entered service the navy was rarely able to give its pilots a satisfactory amount of training.
Engine: One Nakajima Kotobuki 2 air-cooled radial
Power: 600hp at take off, 460hp at 6,825ft
Wing span: 40ft 6 5/8in
Height: 9ft 3 5/8in
Empty Weight: 3,254lb
Loaded Weight: 4,448lb
Max Speed: 175mph at 6,825ft
Cruising Speed: 138mph at 3,280ft
Service Ceiling: 23,950ft
Range: 652 miles
Armament: One forward firing 7.7mm machine gun