August 28, 1945
1st Navy Technical Arsenal

List of Prototype Engines
Manufacturing LocationDesignationEngine TypeBore
Takeoff HPRated HP/Rated Altitude
(mm)(l)1st Speed2nd SpeedNavyArmy
1st Munitions ArsenalHa-45 Model 23Air-cooled R18130×15035.819901860/17501625/61001-stage 2-speed supercharger, low-pressure injectionGinga, Saiun, Shiden Kai, RyūseiKi-84Mass production underway, ground and air testing completed.
Fuel is injected from the front surface of the impeller.
Ha-45 Model 44Air-cooled R18130×15035.819101830/23001640/48001530/80002-stage 3-speed supercharger, low-pressure injectionShiden Kai1st unit completed in the last third of July 1945, in ground testing.
2nd unit and beyond are in manufacturing.
Ha-44 Model 13Air-cooled R18146×16048.223002250/20002080/67001-stage 2-speed supercharger, low-pressure injectionKi-83, Ki-93In prototyping. Next prototype engine after “Ha-45” of the 1st Munitions Arsenal.
In flight testing with Army airframes.
MitsubishiHa-43 Model 11Air-cooled R18140×15041.621502020/11001800/51001-stage 2-speed supercharger, high-pressure injectionReppūKi-87, Ki-74In mass production. 18-cylinder Kinsei engine. In flight testing with both Army and Navy.
Ha-43 Model 42Air-cooled R18140×15041.621001850/20001600/84002-stage Vulkan supercharger, high-pressure injection, extended shaft, pusher modelShindenIn prototyping, engine for the Shinden, in flight testing. 1st and 2nd units are at Kyūshū Airplane. 3rd unit and beyond are in manufacturing.
Ha-43 Model 51Air-cooled R18140×15041.621302000/18001800/50001660/87001-stage 3-speed supercharger, high-pressure injection (axial cooling fan attached)Reppū1st unit completed in the middle third of July 1945, in ground testing.
2nd unit and beyond are in manufacturing.
Ha-42 Model 21Air-cooled R18150×17054.125002300/20002000/64001-stage 2-speed supercharger, high-pressure injectionKi-6718-cylinder Kasei engine, in ground testing.
Ha-42 Model 31Air-cooled R18150×17054.124002130/18001730/83002-stage Vulkan supercharger, high-pressure injectionKi-67In flight testing of “2-stage Vulkan supercharger” with Army Ki-67 plane.
Ha-50 Model 01Air-cooled R22150×17066.130502660/15002510/52001-stage 2-speed supercharger, high-pressure injectionKi-91Japan’s first 22 cylinder engine, world’s most powerful air-cooled engine.
In ground testing.
AichiHa-70 Model 01Liquid-cooled inverted-V 24-cylinder twin 150×16067.834003040/13003000/28001-stage Vulkan supercharger, twin model based on DB606KeiunEquipped inside the fuselage in twin-layout with extended shaft.
In flight testing with Keiun.

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