X-plane simulator

Credit - NASA

Bell X-1 in flight

Credit - NASA

XS-1 Research Team

Credit - NASA

X-1-2 on ramp with Boeing B-29

Credit - NASA

Bell X-1B

Credit - U.S. Air Force Museum

X-1E on Rogers Dry Lake with collapsed nose gear

Credit - NASA

X-1E loaded in B-29 mothership on ramp

Credit - NASA

X-2 with collapsed nose wheel

Credit - NASA

X-2 after drop from B-50 mothership

Credit - NASA

Chuck Yeager with Glamorous Glennis

Credit - Edwards Air Force Base

Bell X-2

Credit - Edwards Air Force Base

X-3 cockpit

Credit - U.S. Air Force Museum

Douglas X-3 "Stiletto"

Credit - U.S. Air Force Museum

Northrop X-4

Credit - U.S. Air Force Museum

D-558-1 in flight

Credit - NASA

D-558-2 being mounted to P2B-1 mothership

Credit - NASA

D-558-2 dropped from B-29 mothership

Credit - NASA

D-558-2 in flight with F-86 chase plane

Credit - NASA

Stamp commemorating first supersonic flight

Credit - NASA/U.S. Postal Service