Lockheed X-17

The Lockheed X-17 was a three stage solid-fuel research rocket to test the effects of high mach atmospheric reentry. The first stage of the X-17 carried the rocket to a height of 17 mi before burning out. The rocket would then coast on momentum to about 100 mi before nosing down for reentry. The second stage engine would then fire before jettisoning and igniting the third and final stage. On April 24, 1957, an X-17 reached a speed of 9000 mph at Patrick AFB. Ultimately the X-17 would be travelling towards earth at up to Mach 14.5.

The X-17 was also used as the booster for the Operation Argus series of three high-altitude nuclear tests conducted in the South Atlantic in 1958.