Often thought to be a Messerschmitt Bf 109, the Kawasaki Ki-61 certainly had the distinctive nose shape associated with an inverted V-12 inline engine, the Kawasaki Ha-40 being in effect a Daimler- Benz DB 601A built under licence in Japan. The Ki-61 was designed by Takeo Doi and his deputy Shin Owada. It was designed in response to a tender by the Technical Branch of the Imperial Army Air Headquarters late in 1939 The Ki-61 was the only Japanese fighter powered by a V-12 inline engine during WW II

One of the first Ki.61-1a's

In December 1940 instructions to go ahead with the Ki-61 were given, and one year later the prototype was flown. The first production Ki-61-I fighters were deployed operationally in April 1943 when the 68th and 78th Sentais arrived in New Guinea. Named Hien (swallow) in service (and codenamed 'Tony' by the Allies),

the new aircraft proved popular with its pilots, being unusually well-armed and armoured, and the type was at least a match for opposing American fighters. Its armament (of four 12.7-mm machine-guns) proved inadequate to knock down enemy bombers, however, and the Ki- 61-I KAIc was introduced with a pair of 20-mm cannon in the nose, these being replaced in a small number of Ki-61- I KAId fighters by two 30-mm cannon.

The Ki-61- I and Ki-61-I KAI remained in production until 1945, but in 1944 they were joined in service by the Ki- 61-II with more powerful Kawasaki Ha- 140 engine (producing 1119-kW); with a top speed of 610km/h this would have been an excellent fighter but for constant engine problems; yet when fully serviceable the Ki-61-II was one of the few Japanese fighters fully able to combat the Boeing B-29 at its normal operating altitude, particularly when armed with four 20-mm cannon. Excluding prototypes and development aircraft, production totalled 1,380 Ki-61-Is, 1,274 Ki- 61-I KAIs and 374 Ki-61-Ils.

The destruction of the Kawasaki engine plant, by a B-29 bombing raid resulted in the fitting of a Mitsubishi Ha 112-II radial engine into 275 Ki-61-II airframes. This combination was designated the Ki-100 a truly outstanding air craft. .

Ki.100

cockpit