Curtiss XF15C

The Curtiss XF15C-1 is a mixed-propulsion fighter prototype of the 1940s. It was among a number of similar designs ordered by the US Navy before pure-jet aircraft had demonstrated their ability to operate from carriers and the mixed-propulsion designs were abandoned. Only three prototypes were constructed, the first one having crashed in testing while the second was scrapped and the last survives to this day.
Development.
By the late 1940s, the United States Navy was interested in the mixed-power concept for its shipborne fighters. Jet engines of that era had very slow throttle response, which presented a safety concern in the case of a missed approach on an aircraft carrier as the aircraft might not be able to throttle up quickly enough to keep flying after leaving the end of the deck. This led to orders for a number of mixed-propulsion fighters, including 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 R-2800 Double Wasp propeller engine, and an Allis-Chalmers J36 turbojet, the aircraft was in theory the fastest fighter in the US Navy at that time.
Operational history.
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 8 May, 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.