X-15 with SLR99 rocket engine

Credit - Edwards Air Force Base

X-15 in flight

Credit - NASA

X-15 shock waves

Credit - NASA

X-15 on lakebed with B-25 mothership flyover

Credit - NASA

X-15 pilots

Credit - NASA

X-15 mounted to B-52 mothership pylon in flight

Credit - NASA

Pilot Neil Armstrong and X-15#1

Credit - NASA

"X-15 crash at Mud Lake, Nevada"

Credit - NASA

X-15 mated to B-52 captive flight

Credit - NASA

Attitude control simulator for X-15 studies at Langley

Credit - NASA