Consolidated Vultee XP-81
|Consolidated Vultee XP-81|
|Maiden flight||11 February 1945|
|Primary user||United States Air Force|
|Unit cost||US$4.6 million for the program|
The Consolidated Vultee XP-81 was a development of the Consolidated Vultee Aircraft Corporation to build a single seat, long range escort fighter that combined use of both a turbojet and a turboprop engines. Although promising, a lack of a suitable engine combined with the end of World War II doomed the project.
Design and development
Two prototype aircraft were ordered on 11 February 1944 that were designated XP-81. The choice of engines was predicated upon an attempt to couple the performance of the jet engine with the endurance offered by the propeller engine. The XP-81 was designed to use the General Electric TG-100 turboprop engine in the nose driving a four bladed propeller and an Allison built J33 turbojet in the rear fuselage. The TG-100 was later re-designated XT-31. The turboprop would be used for normal flight and cruising and the turbojet added for high-speed flight.
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 February 11, 1945. During ten flight test hours, the XP-81, although it encountered poor directional stability (corrected by later modifications to the tail), in other respects, the prototypes displayed fine handling characteristics. 
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 canceled, after 85 percent of the engineering was completed. The YP-81 was to be essentially the same as the prototype but with a lighter, more powerful TG-110 turboprop engine, the wing moved aft ten 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. However, the turboprop engine was not able to produce its designed power and was limited to approximately the same power as the Merlin engine supplied (1,490 hp or 1110 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 ignominiously consigned to a bombing range as photography targets. 
Note: Performance is estimated with 'full powered' TG-100
- Crew: 1
- Length: 44 ft 10 in (13.67 m)
- Wingspan: 50 ft 6 in (15.39 m)
- Height: 14 ft 0 in (4.27 m)
- Wing area: 425 ft² (39.5 m²)
- Empty weight: 12,755 lb (5,786 kg)
- Loaded weight: 19,500 lb (8,850 kg)
- Max takeoff weight: 24,650 lb (11,180 kg)
- Maximum speed: 507 mph (440 knots, 811 km/h)
- Range: 2,500 mi (2,200 nm, 4,000 km)
- Service ceiling: 35,500 ft (10,800 m)
- Rate of climb: 5,300 ft/min (26 m/s)
- Wing loading: 106 lb/ft² (518 kg/m²)
- Knaack, Marcelle Size. Encyclopedia of US Air Force Aircraft and Missile Systems: Volume 1 Post-World War II Fighters 1945-1973. Washington, DC: Office of Air Force History, 1978. ISBN 0-912799-59-5.
- Green 1961, p. 34.
- Winchester 2005, p. 74.
- Green, William. War Planes of the Second World War - Fighters, Volume 4. London: MacDonald,1961.
- Winchester, Jim. The World's Worst Aircraft: From Pioneering Failures to Multimillion Dollar Disasters. London: Amber Books Ltd., 2005. ISBN 1-904687-34-2.
- Pre-1948 USAAF/C:
- Post-1948 USAF:
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