Wind tunnel testing for supersonic vehicles?

Question

How is the aerodynamics model testing (read: wind tunnel) for supersonic vehicles different from those on sub-sonic vehicles?

Does the fact that these vehicles (planes, cars) travel at speeds greater than that of sound in air pose interesting problems with respect to generating stream velocities in a wind tunnel?

Answer 1

A supersonic wind tunnel requires a lot more power than a subsonic one.  Aside from that, there isn't much difference.