There was a demon waiting for rocket ships reaching speeds of Mach 2 or more in the thin air up around 70,000 feet: instability in the yaw or roll axis... followed by an uncontrollable tumble. Sometimes it took the form of "inertia coupling", which usually occurred when a pilot tried to bank a rocket ship and it snapped into a full roll and then began pitching and yawing-and rolling violently. This would throw it end over end. Some pilots felt that the formal term "inertia coupling" added damned little to your understanding of the phenomenon. The ship simply "uncorked" (as one pilot liked to put it) and lost all semblance of aerodynamics and fell out of the sky like a bottle or a length of pipe. There was no way to maneuver out of a rocket-plane tumble. The pilot took a furious beating from the g-forces and from being thrown about the cockpit. The more one experimented with the controls, the worse fix one was in. The first rocket pilot to go through this particular hole in the supersonic envelope was battered unconscious and fell seven miles before hitting the denser atmosphere at 25,000 feet and coming to and managing to put the ship into a spin. >>

(I'm not coming home.)