Robert Clark schrieb:

Haven't taken it that far frankly. But a possibility might be the heat
exchangers planned for the Skylon:

These are a nice concept, but unfortunately will not work for you.

What you want to do is to use the exhaust stream, which travels at
supersonic velocity, and use that for coolig. This runs into the
problem of compressive heating (aka adiabatic temperature increase
upon compression) of the gas, and loss of specific impulse from
slowing down the

What they do is to slow down the incoming air, which also increases
the temperature up to rather high temperatures (~1350K), and
then use the liquid hydrogen to cool down the air to save work on
compression and increase efficiency. Nice concept (if ambitious).