World War II Database

Contributor: Alan Chanter

ww2dbaseThe Mitsubishi Ki-51 was designed to meet a Japanese Army requirement in 1937 for a ground-attack aircraft. The company's design team came up with what was virtually a scaled down version of the company's Ki-30 light bomber except that, as a bomb bay was not required, the wing was dropped from a mid to a low-set position and a revised cockpit layout was provided for the two man crew. Two prototypes were built, both powered by the same 940-horsepower Mitsubishi Ha-26-II radial engine, and these were flight tested in the summer of 1939. The prototypes were followed by eleven service trials aircraft which introduced armoured protection for the engine and crew. In addition aerodynamic refinements were incorporated in order to improve the aircraft's low-speed handling.

ww2dbaseHaving passed its service trials the Ki-51 was accepted by the Japanese Army with the designation of Army Type 99 Assault Plane, although the Allies would allocate the codename "Sonia" to the type. First employed in China, the Ki-51 would see service throughout the Pacific War, although its vulnerability to Allied fighters meant that it was usually confined to secondary theatres of war. In the closing stages of the war however numbers were employed for special attacks on American shipping.

ww2dbaseProduction eventually totalled 2,385 machines of which Mitsubishi built 1,472 and the Tachikawa 1st Army Air Arsenal built 913.

SPECIFICATIONS

Ki-51

Machinery	One Mitsubishi Ha-26-II radial engine rated at 940-hp
Armament	2x7.7mm (later 2x12.7mm) forward machine guns, 1x7.7mm rear machine gun, up to 411-lb external bombs
Span	12.10 m
Length	9.20 m
Height	2.73 m
Wing Area	24.02 m²
Weight, Empty	1,873 kg
Weight, Loaded	2,920 kg
Speed, Maximum	425 km/h
Service Ceiling	8,270 m
Range, Normal	1,060 km

Photographs