Consolidated Vultee XP-81 - Operational History

Operational History

The first XP-81 (serial 44-91000) was completed in January 1945 but because of developmental problems the turboprop engine was not ready for installation. A decision was then made to mount a complete V-1650-7 Merlin engine package from a P-51D aircraft in place of the turboprop for initial flight tests. This was done in a week and the Merlin-powered XP-81 was sent to the Muroc airbase where it flew for the first time on 11 February 1945. During 10 flight test hours, the XP-81 displayed good handling characteristics except for inadequate directional stability due to the longer forward portion of the fuselage (this was rectified by enlarging the vertical tail).

While 13 YP-81 pre-production aircraft had been ordered, the capture of Guam and Saipan removed the need for long-range, high-speed escort fighters and, then, just before VJ Day the contract was cancelled, after 85% of the engineering was completed. The YP-81 was to be essentially the same as the prototype but with a lighter, more powerful GE TG-110 (XT41) turboprop engine, the wing moved aft 10 inches (0.25 m), and armament of either six .50 cal (12.7 mm) machine guns or six 20 mm cannon.

After the XP-81 was returned to Vultee Field, the TG-100 turboprop was installed and flight testing resumed, including the first flight by an American turboprop-powered aircraft on 21 December 1945. However, the turboprop engine was not able to produce its designed power; producing only the same output as the Merlin (1,490 hp or 1112 kW) with the resultant performance limited to that of the Merlin-powered configuration.

With the termination of hostilities, the two prototypes continued to be tested until 1947 when they were both consigned to a bombing range as photography targets.