The X-1E, the last of the X-1 aircraft series, was used to obtain in-flight data at twice the speed of sound, with particular emphasis placed on investigating the improvements achieved with the high-speed wing. The airplane was the first aircraft to fly supersonically with a 4% wing, and thus the first to prove the high-mach capability and adequate stability using a thin airfoil section.
The X-1E made 26 flights and a captive flight with two NACA High-Speed Flight Station test pilots. It flew to a Mach of 2.24 and
an altitude of 73,458 feet. Like its predecessors is was air launched from a Boeing B-29.
