XFV-1 and the Hiller X-18 tilt-wing research aircraft. Fitted with the more powerful 7,100shp YT40-A-6 the XFY-1 flew the first full flight from vertical take-off to horizontal flight and back to vertical flight for landing, of a fixed wing aircraft, in November 1954. Continuing concerns over propellers and the poor payload and performance precluded further development. Some flying was carried out with the Hiller X-18 but most research was carried out with the aircraft attached firmly to a force measuring platform, that could be raised hydraulically, to gather data on ground cushion effects. Limited flying was carried out by the two Republic XF-84H Thunderscreech turboprop fighter aircraft, but the continuing difficulties with the T40 engine, supersonic propeller, not to mention performance completely overshadowed by contemporary rivals led to cancellation of production plans. Applications Data from: Convair P5Y and R3Y Convair XFY Pogo Douglas A2D Skyshark Hiller X-18 Lockheed XFV North American XA2J Super Savage Republic XF-84H Thunderscreech Variants Model 500 Company designation for the T40 Model 501 Company designation for the T38 (half a T40, for development of the T40) Model 501-D Company designation for the T56 Model 503Company designation for the T44 XT40-A-1 XT40-A-2 T40-A-4 XT40-A-5 XT40-A-6 XT40-A-10 YT40-A-14 T40-A-20 T40-A-22 T44 (Model 503), with three power sections; none were built and the project was cancelled. T54-A-2 Re-designed T40 giving equivalent. After the initial limited success of the T40 the US Navy sponsored development of a new turboprop about 28% larger than the T40, but this work was soon overtaken by the Allison T56 / Allison 501-D and development was cancelled. T56 (Model 501-D) Successful development of the T40 / T38 with a single power section. Specifications (T40-A-6) See also References Further reading External links Flight 1950 article Dual Turbine Produces 5,500 h.p. early article with good illustration showing how two engines are connected to one gear box "American Turboprops" a 1950 Flight article "Tradewind Turboprops" a 1955 Flight article T40 1940s turboshaft engines 1950s turboshaft engines