The Mitsubishi Ki-30 'Ann' was produced as part of the Japanese Army's modernization programme of the mid 1930s, but although its design contained a number of technical 'firsts' for Japan it was a mediocre aircraft, and suffered heavy losses when it came up against determined resistance.
By 1936 the modernization programme had produced new fighters, heavy bombers and reconnaissance aircraft, but the Kawasaki Ki-3 and Mitsubishi Ki-2 remained the only light bombers in service. In May 1936 Mitsubishi and Kawasaki were each asked to produce two prototypes for a new light bomber. The new aircraft was to have a maximum speed of 248.5mph at 9,845ft, a normal bomb-load of 661lb, a maximum bomb-load of 992lb and to use one of three possible engines providing 825-850hp.
The eventual Mitsubishi design was a mid-wing monoplane, with an internal bomb bay and a fixed undercarriage. The first prototype was powered by a Mitsubishi Ha-6 radial engine, and made its maiden flight on 28 February 1937. The second prototype, powered by a Nakajima Ha-5 radial engine followed later in the same month. It would be the first operational Japanese army aircraft to be powered by a double-row radial engine, to use an internal weapons bay, have a variable pitch propeller and to have split flaps on the wings.
Both prototypes had better than required performance. The army ordered sixteen service trial aircraft, powered by the Nakajima Ha-5 KAI radial. These were completed by January 1938, and mass production began in March 1938. Mitsubishi built 618 production aircraft, ending in April 1940, another 68 aircraft were built by Tachikawa Dai-Ichi Rikugen Kokusho between 1939 and September 1941
The Ki-30 made its combat debut over China, where it operated with fighter cover and performed quite well. Its pleasant flying characteristics made it popular with its pilots. After Japan entered the Second World War the Ki-30 was used successfully over the Philippines, but as soon as it came up against fighter opposition its lack of speed and defensive armament meant that it suffered heavy casualties. The Ki-30 was quickly withdrawn from the front line, and was used for crew training. Towards the end of the war surviving aircraft were used to carry out kamikaze suicide attacks.
Engine: One Nakajima Ha-5 KAI 14-cylinder radial
Power: 950hp at take-off, 960hp at 11,810ft
Wing span: 47ft 8in
Length: 33ft 11in
Height: 11ft 11in
Empty Weight: 4,916lb
Loaded Weight: 7,324lb
Max Speed: 263mph at 16,405ft
Cruising Speed: 236mph
Service Ceiling: 28,120ft
Range: 1,056 miles
Armament: Two 7.7mm machine guns, one in port wing, one in rear cockpit
Bomb-load: 882lb/ 400kg maximum, 661lb normal