US Navy interest in the mixed-power concept for shipboard fighters - aircraft employing a piston engine for cruise and an auxiliary turbojet to provide supplementary power for take-off, climb and maximum speed - which had resulted in orders for three prototypes of the Ryan XFR-1 and 100 production FR-1s, was taken a stage further on 7 April 1944 with the placing with Curtiss of a contract for three prototypes of the appreciably more powerful XF15C-1. This was to be powered by a 2,100hp Pratt & Whitney R-2800-34W 18-cylinder tworow radial and a 1226kgp Allis-Chalmers J36 (Halford H-1B) turbojet. Armament was to comprise four wing-mounted 20mm cannon. The first XF15C-1 was flown on 27 February 1945, without the turbojet installed, this being fitted by April, but the aircraft was lost on 8 May when it crashed during a landing approach. The second XF15C-1 flew on 9 July 1945, and was joined soon after by the third, both subsequently having their low-set horizontal tail surfaces replaced by a T-tail arrangement. The flight test programme continued until October 1946, by which time the US Navy had lost interest in the mixed power arrangement and cancelled further development.