"Scram-jet" engine or supersonic combustion ramjet engines.

-They begin to work when they reach the speed of sound increased several times, almost 5 Mach and to reach much more (9 or 10 Mach).

-The Hyshot III launched in Australia reached 7'6 Mach at 314 km high (note from the BBC).

-It was installed on the second stage of a Terrier-Orion.

“Hyshot III test”