Unknown
| XP-81 | |
|---|---|
 | |
| Role | Escort fighter |
| Manufacturer | Consolidated Vultee Aircraft Corporation |
| First flight | 11 February 1945 |
| Status | Cancelled |
| Primary user | United States Army Air Forces |
| Number built | 2 |
| Unit cost | US$4.6 million for the program[1] |
Contents
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Design and development
Two prototype aircraft were ordered on 11 February 1944 that were designated XP-81. The engine selection was an attempt to couple the high-speed capability 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 (later designated XT31 by the US military) in the nose driving a four-bladed propeller and an GE J33 turbojet in the rear fuselage. The turboprop would be used for normal flight and cruising and the turbojet added for high-speed flight.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).[2]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. 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.[3][4] Both prototypes are currently in storage at the National Museum of the United States Air Force near Dayton, Ohio.[5]
Operators
- United States Army Air Forces (testing only)
Specifications (XP-81)
Note: Performance is estimated with "full powered" TG-100. Armament is projected only.
- 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)
- Powerplant:
- 1× General Electric J33-GE-5 turbojet, 3,750 lbf (16.7 kN)
- 1× General Electric XT31-GE-1 (TG-100) turboprop, 2,300 hp (1,700 kW)
- 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)
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