[jaipilot747]

Is there even a hydrogen turbojet engine?

[moffkalast]

Afaik it's one of the three H2 airframe options Airbus is pursuing.

https://www.airbus.com/en/innovation/low-carbon-aviation/hyd...

The general idea is to use liquid H2, like the old KN-88 design.

https://en.wikipedia.org/wiki/Kuznetsov_NK-88

[twic]

Maybe not in service, but it's been done: https://www.reuters.com/business/aerospace-defense/rolls-roy...