The Bell X-1 was the first crewed airplane to exceed the speed of sound in level flight and was the first of the X-planes.
XS-1 pilots
PilotAgencyFlightsAircraft Joseph Cannon Bell Aircraft 1 46-064 Chalmers "Slick" Goodlin Bell Aircraft 26 46-062 (9), 46-063 (17) Alvin "Tex" Johnston Bell Aircraft 1 46-063 Jack Woolams Bell Aircraft 10 46-062 Robert Champine NACA 13 46-063 Scott Crossfield NACA 10 46-063 John H. Griffith NACA 9 46-063 Herb Hoover NACA 14 46-063 Howard Lilly NACA 6 46-063 Joseph A. Walker NACA 2 46-063 Fred Ascani USAF 1 46-063 Albert Boyd USAF 1 46-062 Frank Everest USAF 10 46-062 James Fitzgerald USAF 7 46-062 Patrick Fleming USAF 1 46-062 Richard Johnson USAF 1 46-062 Gustav Lundquist USAF 6 46-062 Jack Ridley USAF 5 46-062 Chuck Yeager USAF 34 46-062 (33), 46-063 (1)
XS-1 flights