Technical problems with inline engines Ha-40 and Ha-140, which were powered fighter aircraft Kawasaki Ki-61 Hien, has forced the search for a new solution. Kaigun Kōkū Hombu recommended the use of, their drive, proven air-cooled radial engines Mitsubishi Ha-112-II Kinsei (Venus) 1500 hp. The new construction was given the designation Ki-100, and ordered the rapid development of the project and construction of the prototype. Installation radial engine in place inline, posed serious problems. The new engine was almost twice as wide of an existing fuselage. In order to overcome the problems, engineers analyzed the structure of the German fighter Focke-Wulf Fw 190 also used the experience gained during the conversion bomber Yokosuka D4Y diving. A rebuilt fighter prototype made its maiden flight on February 1, 1945. In February and March 1945 were established two prototypes. Production of the aircraft started in March 1945. It lasted until mid-August 1945.
Official name: 五式戦闘機 – rikugun 5 shiki sentouki (Army Type 5 Fighter)
Ki-100 (prototypes): one batch of Kawasaki Ki-61-II Kai with radial engine. 3 built
Ki-100 I-Ko – initial model of series, KI-61 II Kai fuselage, ~271 built
Ki-100-I Otsu – bubble top canopy – 118 built as such.
Ki-100-II (prototypes) – high-altitude fighter-interceptor, engine Mitsubishi Ha-112-II Ru with turbocharger, 1120 kW (1500 hp). 3 built.
Ki-119 (only project) design influenced by the fuselage of the Ki-100, was to have been a fighter-bomber aircraft.
I.J.Army Kawasaki typ 3 & 5 Fighter – Model Art Magazine 428, 1994
Kawasaki Ki.61 Ki.100 Hien in Japanese Army Air Force Service – Richard M. Bueschel, Osprey Publishing Aircam Aviation Series 21
Ki-61, Ki-100, Ki-48 – Mechanism of Military Aircraft 2
Ki-61 and Ki-100 Aces – Nicholas Millman, Osprey Publishing Aircraft of the Aces 114
Kawasaki Ki-61 Hien Ki-100 – Leszek A. Wieliczko, Kagero Monographs 58
Army Typ 5 Fighter – Famous Airplanes of the World 23 – Bunrin Do, 1990
Japanese Aircraft of the Pacific War – R. J. Francillon, Putnam & Company 1970
Japanese Aircraft Equipment 1940-1945 – Robert C. Mikesh, Schiffer 2004