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 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 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. Operational history In 1947, before the flight testing of the prototypes was completed, 30 production aircraft were ordered. They incorporated an ejection seat and a redesigned vertical stabilizer as well as two auxiliary fins, one towards the tip on each side of the tailplane in an attempt to improve the directional stability of the aircraft. The fuselage was lengthened to fit additional equipment and the wing had fillets added at the rear junction with the fuselage. During the production run, the Navy decided to move the Chance Vought factory from Stratford, Connecticut, to a much larger facility in Dallas, Texas, which had been vacant since the end of World War II; this badly disrupted the production of the Pirate. The airframes were built in Stratford and trucked to Dallas, where government-furnished equipment, such as the engines and afterburners, were installed. The completed aircraft were then taxied around the new plant's airfield, but the runway was deemed too short to handle jets. The aircraft had to be disassembled and trucked to an abandoned airfield at Ardmore, Oklahoma, with a runway long enough for acceptance testing. The first production F6U-1 performed its initial flight on 29 June 1949, and 20 of the aircraft were provided to VX-3, an operational evaluation squadron based at Naval Air Station Patuxent River in Maryland. The judgment from the evaluation was that the Pirate was unacceptable for operational use. Naval aviators disparagingly called the F6U the "groundhog". On 30 October 1950, BuAer informed Vought of the Navy's opinion of the Pirate in terms both bureaucratic and scathing: