The Consolidated Vultee XP-81 (its newly-merged builder soon to be better known as Convair) was the first American aircraft powered by a turboprop engine. Ordered by the USAAF on 11 February 1944, the XP-81 was intended as a long-range escort fighter using compound power, with one 1230kW General Electric TG-100 turbo-prop and one 1701kg thrust Allison I-40 jet engine, eventually designated J33-A-5. When delays with the turboprop powerplant were encountered, the prototype XP-81 was flown on 11 February 1945 with a Packard V-1650-7 Merlin installed temporarily in the nose. The first flight with the intended turboprop engine followed on 21 December 1945 and, to the astonishment of pilots and observers, the turboprop provided no advantage in performance over the Merlin! A second XP-81 flew in early 1946 to join the first machine in exploring the potential for this unusual powerplant, but several factors (war's end, the disappointing results with the TG-100, and the evident, superiority of pure jet designs) resulted in cancellation of an order for 13 YP-81 service-test aircraft.

Both XF-81 airframes have survived, albeit in poor condition, and are today derelict on a test range at Edwards AFB, California, known until 1949 simply as Muroc Dry Lake.