American manned spaceplane used for hypersonic research. Conducted tests for ballistic flight, winged reentry, and gliding recovery. The X-15 was intended to evolve to a manned orbital spacecraft until the urgent need for the Mercury and Gemini programs surfaced. Research from the X-15 eventually led to the techniques used by the Space Shuttle.
SpaceX partially reusable heavy-lift launch vehicle derived from the Falcon 9. Consists of a strengthened Falcon 9 first stage center core and two Falcon 9 first stage strap-on boosters. As of 2021, Falcon Heavy had the highest payload capacity of operating rockets and the third highest of any rocket ever to reach orbit.