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Type: Experimental Long-Range Escort Fighter Origin: Consolidated-Vultee Aircraft Corporation Crew: One Model: XP-81 & YP-81 First Flight: February 11, 1945 Production: 1 Prototype (44-91000) Powerplant: Model: General Electric XT31-GE-1 (TG-100) Type: Turboprop Number: One Horsepower: 2,300 hp And Model: Allison J33-GE-5 Type: Turbojet Number: One Static Thrust: 3,750 lb. Dimensions: Wing span: 50 ft. 6 in. Length: 44 ft. 10 in. Height: 14 ft. 0 in. Lifting Surface Area: 425 sq. ft. |
Weights: Empty: 12,755 lb. Loaded: 19,500 lb. Maximum Overloaded: 24,650 lb. Performance: Estimated Maximum Speed: 478 mph at Sea level 507 mph at 30,000 ft. Initial Climb Rate: 5,300 ft. per minute Service Ceiling: 35,500 ft. Range (at 25,000 ft.): 2,500 miles at 275 mph Armament: Proposed Six .50 in. machine guns in wings. Or Six 20mm cannon in wings. Payload: Proposed Two 1,600 lb. bombs. |
The XP-81 was originally conceived to overcome the severe range limitations suffered by the early model jet engines. The designers strove to overcome this problem by creating an aircraft with a hybrid propulsion system. By taking a GE TG-100 turboprop engine driving a four bladed propellor with a Allison J33 turbojet engine, the designers sought to combine endurance with a high top speed.
The prototype, designated XP-81, was completed in January 1945 but the TG-100 turboprop suffered from some development issues and thus was not available for initial flight testing. In order for flight testing to commence a Packard built Merlin (V-1650-7) powerplant package was fitted to the airframe with the radiator being housed in the area reserved for the turboprop exhaust. The prototype was fitted with a P-51D airscrew assembly and after ground tests were completed the aircraft was sent to Muroc where it made it's first flight. Ten hours of flight testing showed the XP-81 to have fine handling characteristics.
The intended purpose of this aircraft was to provide a long-range escort fighter for the Pacific theater but with the fall of Guam, Saipan and other islands the need for this aircraft dissolved. Though 13 YP-81 pre-production aircraft were ordered, the project was eventually cancelled shortly before Japan surrendered. The YP-81 differed from the XP-81 in have a lighter turboprop powerplant (TG-110) and the wing was set back 10 inches.
The prototype eventualy returned to Vultee were the TG-100 powerplant was installed. Flight tests were resumed on December 21, 1945 but proved to be disaapointing. The TG-100 was expected to produce 2,300 hp but in practice produced a lttle over 1,400 hp thus making it no more powerful than the temporary Merlin which produced 1,490 hp. Regardless, the design was rapidly overtaken by the wave of new designs that erupted after the end of WWII.
The Complete Encyclodepia of World Aircraft, 1997, Barnes & Nobles Books, ISBN: 0 7607 0592 5
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