The Kawasaki Ki-100 was Imperial Japanese single-seat, single-engine fighter and interceptor aircraft developed during the last months of the WWII. No Allied code-name was assigned to this type.
When B-29 bombers based in India began, in the summer of 1944, to make high-level attacks on targets in Japan after refueling in China, the Imperial Japanese Air Force had no aircraft capable of intercepting and destroying them, although its intelligence officers had known for some months that runways at airfields near Calcutta and at Chengtu, in China, were being lengthened to accommodate American bombers of exceptional range. The Ki-61 was endowed, in theory, with the necessary high-altitude performance, but it was still in the prototype stage, and the authorities despaired of bringing it into service in time to save the situation unless a more reliable power-unit then the Ha-140 could be found for it.
After studying the German Focke-Wulf Fw-190, Kawasaki`s engineers succeeded in marrying the tubby Mitsubishi HA-112-II radial engine to the slim fuselage of the Ki-61. Of some 375 Ki-61-II KAI airframes produced between the following September and the end of the war, 275 were fitted with Mitsubishi engines and completed a high-altitude fighters/interceptors. Three were used as prototypes with the designation Ki-100, the rest treated as production aircraft and given the designation Ki-100-Ia or Army Type 5 Fighter Model 1A. In addition, about a 100 K-100s were manufactured from scratch and received the designation Ki-100-Ib or Army Type 5 Fighter Model 1B. A version powered by a turbo-supercharged variant of the HA-112-II and given the designation Ki-100-II was projected, but did not get beyond the prototype stage. The Ki-100 could climb 10,000 meters in 20 minutes and was brisk performer at such altitudes, but its armament left a good deal to be desired and many of the handled it had very little operational experience.
The Kawasaki Ki-100 wingspan was 12.00 meters (39 ft 4 in) and length was 8.82 meters (28 ft 11 in). It was powered by single Mitsubishi Ha 112-II radial engine (1,120 kW or 1,500 hp at take off). Maximum speed was 580 km/h (313 knots or 360 mph), and range was 2,200 km (1,367 miles). Total Ki-100 production was 385 units.