|INTERCEPTOR||Virtual Aircraft Museum / Japan / Mitsubishi|
Derived from the Ki-67 Hiryu bomber as a heavy interceptor, the Ki-109 was originally conceived in two versions: the Ki-109-ko mounting two obliquely-firing 37mm cannon and the Ki-109-otsu equipped with radar and a 40cm searchlight. The intention was that the two versions of the aircraft would work as a team. Soon thereafter the Ki-109 project was redefined as a bomber interceptor mounting a 75mm Type 88 cannon with which it could attack its quarry while remaining beyond the range of opposing defensive armament. Converted from a Ki-67 airframe and retaining the dorsal, lateral and tail gun positions of the bomber, and the Mitsubishi Ha-104 engines each rated at 1900hp for take-off, the first Ki-109 prototype was completed in August 1944. The second prototype was powered by Ha-104ru engines with Ru-3 turbo-superchargers, and it was intended that these would be installed in the final 22 aircraft of an initial batch of 42 Ki-109s. The first series Ki-109 dispensed with the dorsal and lateral gun positions, retaining only the tail position which mounted a single 12.7mm machine gun. Primary armament was the single 75mm cannon with 15 shells individually loaded by the co-pilot. In the event, production difficulties with the Ru-3 turbo-supercharger prevented its application to any series Ki-109s, and only 20 production aircraft were completed, these having standard Ha-104 engines.