Douglas F5D Skylancer The United States Douglas F5D Skylancer was a development of the F4D Skyray jet fighter for the United States Navy . Starting out as the F4D - 2N , an all - weather version of the Skyray , the design was soon modified to take full advantage of the extra thrust of the Pratt & Whitney J57 eventually fitted to the Skyray instead of the Westinghouse J40 originally planned . Design and development . Soon the design became too different from the Skyray to be considered just a variation of it , and the aircraft was assigned a new designation as the F5D Skylancer . Almost every part of the airframe was modified , though the basic form remained the same as did the wing shape , though it became much thinner . The wing skinning was reinforced , correcting a problem found in the F4D . The fuselage was 8 ft ( 2 . 4 m ) longer and area ruled to reduce transonic drag , being thinner in the region of the wing roots . Everything was shaped to reduce drag and increase stability at high speed . Although the four 20 mm ( . 79 in ) cannon in the wing roots were retained , primary armament was to be missiles or rockets ; four AIM - 9 Sidewinder s or two AIM - 7 Sparrow s , and / or a battery of spin - stabilized unguided 2 in ( 51 mm ) rockets . Nine test airframes were ordered , with a 51 - aircraft production order to follow . Production aircraft were to be powered by the more powerful J57 - P - 14 engine , while there were plans to use the even more powerful General Electric J79 . Operational history . The first flight was on 21 April 1956 and was supersonic ; the aircraft proved easy to handle and performed well . After four aircraft had been constructed , however , the Navy cancelled its order . The stated reason was that the aircraft was too similar to the already - ordered F8U Crusader , but it is believed by some historians that politics played as big a part ; Douglas was already building a very large proportion of the Navy ' s planes , and giving them the F5D contract would have made it even closer to monopoly . The project test pilot was Lt . Cmdr Alan B . Shepard Jr . whose report stated that it was not needed by the Navy . NASA use . The four aircraft continued to fly in various military test programs . Two were grounded in 1961 , but the other two : F5D - 1 ( Bu . No . 139208 ) NASA 212 , later becoming NASA 708 and F5D - 1 ( Bu . No . 142350 ) NASA 213 , later becoming NASA 802 continued to fly . Transferred to NASA in the early 1960s , one was used as a testbed for the American supersonic transport program , fitted with an ogival wing platform ( the type eventually used on Concorde ; data from the program was shared with the European designers ) . This aircraft was retired in 1968 . NASA 802 was used for simulation of abort procedures for the X - 20 DynaSoar , because it had a very similar shape and handling characteristics . Following the DynaSoar cancellation , it was used as a chase plane and for various other programs until it was retired in 1970 . Survivors . NASA 802 still exists at the Neil Armstrong Air and Space Museum at Wapakoneta , Ohio , since Neil Armstrong flew the aircraft during the Dyna - soar research program . NASA 708 still in NASA markings exists as part of Merle Maine ' s private collection in Ontario , Oregon .