Nakajima Ki-43-II Hayabusa

In 1937 the Imperial Japanese Army asked Nakajima for a successor to its Ki-27, a fixed-undercarriage monoplane that its pilots loved for its agility. Hideo Itokawa’s team designed a slim, light low-wing fighter with a retractable undercarriage, an enclosed cockpit and a Nakajima Ha-25 radial, and the first prototype flew in January 1939. The army’s pilots at first thought it no more agile than the Ki-27 it was meant to replace, and the design was saved only by Nakajima’s ‘butterfly’ combat flaps, which could be lowered in a turn to tighten it. It was adopted as the Army Type 1 Fighter in 1941 and named Hayabusa, ‘peregrine falcon’.

Only about 40 were in service when Japan went to war in December 1941, but over Malaya, Singapore, the Dutch East Indies and Burma the Ki-43 outturned and outclimbed the Buffaloes and Hurricanes it met, and the Allies, who often mistook it for the navy’s Zero, gave it the code name ‘Oscar’. Its weaknesses showed soon enough: it carried only two machine guns, and it had little armour and, at first, no self-sealing tanks. The Ki-43-II, flown in February 1942, answered some of this with the two-speed Ha-115 engine, a three-blade propeller, a shorter span, armour behind the pilot and self-sealing tanks, and it became the main production version.

Nakajima and Tachikawa built 5,919 Ki-43s, more than any other Japanese Army aircraft, and the type fought on every front of the army’s war, from China and Burma to New Guinea, the Philippines and Okinawa, where many ended as suicide aircraft. It was outclassed by 1943, but it stayed in production to the end, and the army never had enough of its successor, the Ki-84. After the war captured Ki-43s were briefly flown by the French in Indochina and by Indonesian forces. A handful survive, most rebuilt from Pacific wrecks, in the United States, Japan and Russia; none is in a UK museum.