Vultee XP-81 Mixed-Power Fighter Prototype Aircraft
The Vultee XP-81 was a combination fighter powered by both turboprop and turbojet powerplant technology.
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The Consolidated Vultee XP-81 was a proposed long-range, high-altitude fighter design that was to be the answer for bomber escorting in Europe but, more importantly, throughout the island hopping campaign of the Pacific. The XP-81 melded together the power of the ever-evolving turbojet engines and the development of America's first turboprop engine.
The single-seat, twin engine fighter was designed around the complicated General Electric powerplant creations that would never live up to expectations with the XP-81 design. To feed the two-engine idea, the aircraft itself was to be of a rather large design for a fighter when compared to its contemporaries in the P-51 Mustang, P-38 Lightning and the P-47 Thunderbolt.
The pilot sat forward of the wing assemblies, offering up tremendous visibility from the bubble canopy overlooking the front part of the aircraft. A four-blade propeller sat at front, powered by the turboprop assembly in the nose. The laminar flow wings sat directly in the center of the design with a low tricycle landing gear system underneath the massive spread. Twin intakes were mounted just aft of the cockpit on the top portion of the fuselage. These intakes were placed as such to feed the single turbojet engine jettisoning exhaust through the rear under the rudder and tail assemblies.
On paper, the design was sound. Estimated capabilities proposed that the system would be able to achieve over 500 miles per hour and reach over 35,000 feet. As impressive ranges were a part of the American aircraft pedigree throughout the war (British and German aircraft seldom were long-range threats to one another), the XP-81 was to have a distance of 2,500 miles - more than enough to keep up with the B-17 and B-29 bomber formations pounding The Reich and the Empire of Japan.
Alas, troubles with the powerplant forced the only flying prototype to be fitted with a P-51 engine alternative. When the turboprop did arrive and was installed, the system produced well under expectations - a full 1,000 horsepower under proposed capabilities in fact. With the war in Europe now held in check by the existing breed of fighter escorts and the island hopping campaigns of the Pacific progressing equally well - though slow-going and costly to US ground forces - the XP-81 project was cancelled along with the order of 13 YP-81 developmental models.
Though envisioned with an armament array of 6 x .50 caliber machine guns, the weapons were never fitted to the aircraft. Provisions for drop tanks or bombs can be assumed. The two surviving prototypes were later found scrapped of most anything of value and, as of this writing, are awaiting their fate with the USAF - perhaps seeing fit to restore at least one model for the USAF Museum in Dayton, Ohio. A sound concept nonetheless, the twin engine creation never really got off the ground.