The world's first variable-sweep combat aircraft, the XF10F-1 was designed as a transonic single-seat shipboard fighter with an internal armament of four 20mm cannon and provision for an external bomb load of up to 1814 kg. The sweepback angle of the wings could be varied hydraulically between 13.5° and 42.5°, and high-lift devices consisted of full-span slats and an 80% Fowler flap. The Jaguar was intended to be powered by a Westinghouse XJ40-WE-8 turbojet rated at 3357 kg military thrust and 4944 kg with afterburning, but when flight trials were initiated on 19 May 1952, a J40-WE-6 rated at 3084 kg was fitted. Numerous problems arose during the test programme, and as some of these could not be resolved, trials terminated with the 32nd flight on 25 April 1953. Orders had been placed for 1