Now Pratt & Whitney thinks it may have taken the first steps along that path with the Hydrogen Steam-Injected, Intercooled ...

However, the compression of air at Mach 5 causes superheating, so the engine will need to be cooled using a cryogenic heat exchanger. This engine technology could also dramatically cut the ...

Cryogenic: Relating to very low temperatures, typically below -150°C, where superconductivity is achieved. Heat Exchanger: A device that transfers heat between two or more fluids without mixing ...