The Mitsubishi Ki-73 super high-speed (750km/h) experimental fighter was an Army aircraft that was only a partially developed prototype, built as a response to a specification for a single-engined long range escort fighter in May of 1943. The Ki-73 was designed by Tomio Kubo, who was also responsible for the Ki-46 Dinah. The images on this page are speculative models based on what its likely appearance would have been (also see: “Japanese secret projects. Experimental Aircraft of the IJA and IJN 1939 – 1945″ by Edwin M. Dyer), since the vehicle was not completed. Unicraft offers a 1/72 scale model proposal based on the design.
The engine was a horizontal H liquid-cooled 24-cylinder engine of Mitsubishi design – a HA 206 (or Ha-203-II, depending on sources), with an estimated 2,600HP during take off. (Source:All the Experimental Aircraft in the Japanese Army, KANTOSHA, JAPAN) As a whole, the entire Mitsubishi Ha-203-II was considered a single engine. However the design of the Ha-203-II actually used two flat engines, one on top of the other, and geared together.
The unusual dual contra-rotating propeller single engine was apparently plagued by development problems and handling characteristics were iffy with its proposed top speed, and as a result the Ki-73 never progressed to a full protoype. It was, however, an innovative design worth a place in the history books. Tomio Kubo moved on to instead develop the twin engined Ki-83, a successful design which did reach the full prototype stage, incorporating some learning from the Ki-73 design. Despite never having been manufactured, the Ki-73 was given an Allied code name – ‘Steve’ – because captured documents suggested that the aircraft was about to enter service.
In Games: The Ki-73 is an interesting “what if” prototype vehicle suited toward more fantasy-leaning wargames where keeping late-war Japanese planes at a level playing field with other countries is important. The speed, armament, and handling characteristics would need to be guesstimated since most information on the parital prototype was apparently lost.
Game Scenario: The player is a pilot of the lone working prototype of the Ki-73. Very fast, difficult to handle, and armed with four 20mm Army Type2 Ho-5 cannons (2 in each wing), the secretly completed high speed fighter is taken out of its hangar bay as a last resort to chase down a slower but heavily-armed American bomber over Japan.