Bell X - 5 The Bell X - 5 was the first aircraft capable of changing the sweep of its wings in flight . It was inspired by the untested wartime P . 1101 design of the German Messerschmitt company . In contrast with the German design which could only have its wing sweepback angle adjusted on the ground , the Bell engineers devised a system of electric motors to adjust the sweep in flight . Design and development . The incomplete Messerschmitt P . 1101 fighter prototype recovered by United States troops in 1945 from the experimental facility at Oberammergau , Germany , was brought back to the United States . Although damaged in transit , the innovative fighter prototype was delivered to the Bell factory at Buffalo , New York where company engineering staff studied the design closely and led by Chief Designer Robert J . Wood , submitted a proposal for a similar design . Although superficially similar , the X - 5 was much more complex than the P . 1101 , with three sweep positions : 20° , 40° and 60° , creating an in - flight " variable - geometry " platform . A jackscrew assembly moved the wing ' s hinge along a set of short horizontal rails , using disc brake s to lock the wing into its inflight positions . Moving from full extension to full sweep took less than 30 seconds . The articulation of the hinge and pivots partly compensated for the shifts in center of gravity and center of pressure as the wings moved . Even so , the X - 5 had vicious spin characteristics arising from the aircraft ' s flawed aerodynamic layout , particularly a poorly positioned tail and vertical stabilizer which , in some wing positions , could lead to an irrecoverable spin . This violent stall - spin instability would eventually cause the destruction of the second aircraft and the death of its Air Force test pilot in 1953 . The unfavorable spin characteristics also led to the cancellation of tentative plans by the United States Air Force ( USAF ) to modify the X - 5 ' s design into a low - cost tactical fighter for NATO and other foreign countries . Operational history . Two X - 5s were built ( 50 - 1838 and 50 - 1839 ) . The first was completed 15 February 1951 , and the two aircraft made their first flights on 20 June and 10 December 1951 . Almost 200 flights were made at speeds up to Mach 0 . 9 and altitudes of 40 , 000 ft ( 12 , 200 m ) . One aircraft was lost on 14 October 1953 , when it failed to recover from a spin at 60° sweepback . USAF Captain Ray Popson died in the crash at Edwards Air Force Base . The other X - 5 remained at Edwards and continued active testing until 1955 , and remained in service as a chase plane until 1958 . The X - 5 successfully demonstrated the advantage of a swing - wing design for aircraft intended to fly at a wide range of speeds . Despite the X - 5 ' s stability problems , the concept was later successfully implemented in such aircraft as the F - 111 , Grumman F - 14 Tomcat , MiG - 23 , Panavia Tornado and B - 1 Lancer . Survivors . The sole surviving X - 5 is now at the National Museum of the United States Air Force at Wright - Patterson Air Force Base near Dayton , Ohio . It was delivered to the Museum in March 1958 . It is displayed in the Museum ' s Research & Development Hangar .