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big_trike t1_iya1zn5 wrote

Reply to comment by KechtmutAlTunichtgut in Rolls-Royce successfully tests hydrogen-powered jet engine | Britain's Rolls-Royce said it has successfully run an aircraft engine on hydrogen, a world aviation first that marks a major step towards proving the gas could be key to decarbonising air travel. by yourSAS

Combusting hydrogen that starts in the liquid state is tricky. At 1 atmosphere, hydrogen evaporates into a gas at 33K, but oxygen freezes at 54K. On top of that, combustion occurs at much higher pressures in a jet engine. So, while it's definitely possible to make it work, you need an engine design that significantly pre-heats the incoming fuel. The space shuttle main engines do this by scavenging heat from the exhaust and are a marvel of engineering.

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