Flight Operating Instructions for X-5 Airplane : Periscope Film, LLC : 9781935327691 : 1935327690 : 10 Oct 2009 : An outgrowth of the Third Reich's Emergency Fighter Program, the Messerschmitt P.1101 jet fighter featured a radical new design in which the sweep of the wing could be altered in flight. Captured by the Allies before it could be completed, the P.1101 was sent to the United States where it inspired the Bell X-5. Produced by a team led by Robert J. Wood, the X-5 was a true "variable geometry" platform that offered in-flight wing positions of 20?, 40?, and 60?. Far more complex than the P.1101, the X-5 utilized a jackscrew to move the wings along horizontal rails, and disc brakes to lock the wing into position. Two X-5s were built, and almost 200 flights were made between 1951 and 1955. While the design initially showed promise, the X-5 had a tendency to go into a violent spin. That characteristic led to the crash of the second prototype in 1953, an accident that killed test p