The XF6U was a small aircraft with tricycle landing gear and with straight wings and tail surfaces. The wings were short enough that they did not need to fold. In order to fit more aircraft into crowded hangars, the nose gear could be retracted and the aircraft's weight would rest on a small wheel attached by the ground crew. This raised the tail up so that it could overlap the nose of the aircraft behind it. The jet engine was mounted in the rear of the fuselage and was fed by ducts in each wing root.

The most unusual feature of the aircraft was its use of "Metalite" for its skin. This was made of balsa that was sandwiched between two thin sheets of aluminum. "Fabrilite" was also used for the surfaces of the vertical stabilizer and rudder; this was similar to Metalite, but used fiberglass instead of aluminum. Two fuel tanks were fitted in the center of the fuselage. The forward tank, ahead of the wing, contained 220 US gallons (830 l; 180 imp gal) and the rear tank, 150 US gallons (570 l; 120 imp gal). These were supplemented by two jettisonable 140-US-gallon (530 l; 120 imp gal) tip tanks. The cockpit was well forward and was provided with a bubble canopy which gave the pilot good visibility. He was provided with a Mk 6 lead-computing gyro gunsight. Underneath the cockpit were four 20 mm M3 autocannon. Their 600 rounds of ammunition were carried behind the pilot. The empty casings of the two upper guns were retained in the aircraft, while those from the two lower guns we re ejected overboard.

After a company-wide contest to name the aircraft, the initial prototype, named the Pirate, made its first flight on 2 October 1946. Flight testing revealed severe aerodynamic problems, mostly caused by the airfoil section and thickness of the wing. The vertical stabilizer also had to be redesigned to smooth out the airflow at the intersection of the horizontal and vertical stabilizers. Other changes included the addition of dive brakes on the sides of the fuselage and the replacement of the Metalite panels near the engine's exhaust with stainless steel ones.

The first XF6U-1 prototype was powered by a Westinghouse J34-WE-22 turbojet with 3,000 lbf (13.34 kN) thrust, one third of the weight of the aircraft. To help improve the underpowered aircraft's performance, the third prototype, which first flew on 10 November 1947, was lengthened by 8 feet (2.4 m) to use a Westinghouse J34-WE-30 afterburning engine of 4,224 lbf (18.78 kN) thrust, the first United States Navy fighter to have such a powerplant.

Sources:
Wikipedia