Hypersonic flow:
In aerodynamics, hypersonic speeds are speeds that are highly supersonic. In
the 1970s, the term generally came to refer to speeds of Mach 5 (5 times the
speed of sound) and above. The hypersonic regime is a subset of the supersonic
regime. Hypersonic flow is characterized by high temperature flow behind a shock
wave, viscous interaction, and chemical dissociation of gas.