[Army Air Corps]

The FAI established the edge of space at 100km (62mi) and two X-15 flights exceeded that altitude.

[doorgunner69]

I never realized until I read the book that the X actually did a re-entry on a lot of flights. That was how they lost one bird when the pilot got messed up and re-entered sideways or backwards.

I'd think the SCRAM will always stay in air thick enough for aerodynamic control surfaces to have some traction. Do not recall reading what altitude the thing is projected to operate at.