By the late 1940s, the United States Navy was interested in the mixed-power concept for its shipborne fighters - i.e. aircraft with a mixture of propellor and turbojet engines, such as the FR Fireball. As such, an order was placed with Curtiss on 7 April 1944 for delivery of three mixed-power aircraft, designated the F15C. Powered by both a 2,100 hp (1,566 kW) Pratt & Whitney propellor engine, and an Allis-Chalmers J36 turbojet, the aircraft was in theory the fastest fighter in the US Navy at that time.
The first flight of the first prototype was on 27 February 1945, without the turbojet installed. When this was completed in April of the same year, the aircraft flew several mixed-power trials, however on May 8 it crashed on a landing approach. The second prototype flew for the first time on 9 July, again in 1945, and was soon followed by a third prototype. Both aircraft showed promise, however by October 1946 the Navy had lost interest in the mixed-power concept and cancelled further development.
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http://en.wikipedia.org/wiki/Curtiss_XF15C
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