POWER PLANT: One Kawasaki Ha 40 liquid-cooled engine, rated at 1,100 hp
PERFORMANCE: No data available
COMMENT: In the summer of 1941, Rikugun Kokugijutsu Kenkyujo (Japanese Army Aerotechnical Research Institute, short named “Kogiken”) formed a design group under the leadership of Ando Sheigo. The task was to study Japanese aviation technology in terms of what was possible at present and in the near future. Additionally, some effort was to be spent on reviewing the aircraft technology of other countries. From the results the group was to assemble and draft proposals for aircraft to fill various pre-determined roles: heavy fighter, light bomber, heavy bomber and reconnaissance. For a bigger idea pool, Imperial Japanese Army (IJA) main aircraft providers, Kawasaki and Tachikawa, were invited to join the group, too. In that period projects such as Kogiken Plan III Revised light bomber and Kogiken Plan V Revised light bomber were designed and proposed to the IJA.
Among fighter designs the Kogiken Plan I Type A was a single seat heavy fighter and a Japanese adaption of the Bell P-39 “Airacobra” mid-fuselage engine concept. The aircraft was designed end 1941 and should be powered by a single Kawasaki Ha 40 liquid-cooled in-line engine, derived from the German Daimler-Benz DB 601A. The engine was installed immediately aft the cockpit driving a four-bladed puller propeller via an extension shaft. A tricycle landing gear was provided similar to the Bell P-39. Armament consisted of 37 mm Ho-203 or 20 mm Ho-5 canon firing through the propeller hub and two wing-mounted 12.5 mm Ho-103 guns. No further details are known, the project never left the drawing board (Ref.: Parts from Unicraft).
POWER PLANT: Two radial engines, rated at 1,450 hp each
PERFORMANCE: No data available
COMMENT: This design of a light bomber dates back to autumn 1941. A blueprint became available after the end of WW II showing a detailed three-view of the project and some important physical dimensions. It might be possible that this design may have had influence on the development of the Kawasaki Ki-102 (Allied code ‘Randy’). Furthermore, the design shows some similarity to the Grumman XP-50, forerunner of the Grumman F7F “Tigercat” (Ref.: 24).
POWER PLANT: One Mitsubishi Ha-211 Ru radial engine, rated at 2,200 hp
PERFORMANCE: 454 mph at 32.810 ft
COMMENT: In 1943 Mansyu offered the Japan Army Air Force a project of a single-seat ground attack aircraft designated Ki-98. The design was of twin boom configuration and was powered by a 2,200 hp turbosupercharged Mitsubishi Ha 211 Ru radial engine mounted in the central nacelle behind the pilot’s seat and driving a four-blade pusher propeller. Nose-mounted armament consisted of one 37 mm and two 20 mm cannon. A prototype was still under construction when Japan surrendered in September 1945 (Ref: 1)
POWER PLANT: Two radial engines, type not available
PERFORMANCE: No data available
COMMENT: Poorly documented JAAF-project of a light bomber with twin fuselage, two radial engines and pilot and gunner/radio-operator seated in the left fuselage. Similar designs during World War II were in Germany Arado E,580 (project), Messerschmitt Me 109Z (flown, Z for Zwilling = twin), Messerschmitt Me 308 (project), Messerschmitt Me 609 (project), Dornier Do 635 (Junkers Ju 8-635) (project),and Heinkel He 111Z (flown), and in the United States North American P-82 (flown).
POWER PLANT: One Kawasaki Ha-140 liquid-cooled engine, rated at 1,500 hp
PERFORMANCE: 373 mph at 19,685 ft
COMMENT: The Kawasaki Ki 88 was designed as a fighter aircraft and inspired by the Bell P-39 Airacobra. Work on the design began in 1942 and by 1943 a full-scale mock-up was completed. The engine was mounted behind the cockpit, driving a tractor propeller via an extension shaft. Proposed armament comprised a 37 mm cannon in the propeller shaft and two 20 mm cannon in the lower section of the nose. Calculation suggested no great improvement on that of the Kawasaki Ki-61 Hien already in production, and so the project was abandoned during 1943 (Ref.: 1).
POWER PLANT: One Kawasaki Ha-40 liquid-cooled engine, rated at 1,175 hp
PERFORMANCE: 370 mph at 15,950 ft (estimated)
COMMENT: The Nakajima Ki-62 was a light fighter designed in 1941 to compete with the Kawasaki Ki-61 “Hien”. Although this design appeared to be promising, its development was discontinued to enable Nakajima to concentrate on production of their Ki-63 “Hayabusa” and Ki-44 “Shoki” fighters. Later, the Ki-62’s data and design features were incorporated in the Nakajima Ki-84 “Hayate” design (Ref.: 1).
POWER PLANT: One Mitsubishi Ha 203-II liquid-cooled engine, rated at 2,600 hp, driving three-bladed contra-rotating propellers
PERFORMANCE: 466 mph
COMMENT: During May 1943, Japanese authorities delivered a new requirement for a single-seat, single-engine long range escort fighter to protect bomber formations from interception by Allied warplanes beginning to gain the advantage in the skies over the Pacific Area of Action. The Mitsubishi Ki-73 was one result of the requirement by the type was not furthered beyond a sole, incomplete prototype before the end of WW II. The design team managed to find success with the earlier twin-engine Mitsubishi Ki-46 “Dinah” and eventually moved on to the promising Mitsubishi Ki-83 twin-engine, two seat long-range heavy fighter design of which four prototypes ultimately emerged when the development of the Ki-73 was abandoned. Rather unique for Japanese-originated wartime fighter design was the use of contra-rotating propeller arrangement. The rest of the overall design arrangement was conventional – the engine in the nose, a single-finned tail at rear and cockpit set over center mass. Wings were straight monoplane appendages with clipped tips and tailwheel undercarriage was fully retractable. While the Mitsubishi Ki-73 was never formally adopted for service and never entered serial production, captured documents by the Allies – who believed the type was to come online soon – allocated the codename “Steve” for the series which never was.