[Colinsky]

I don’t ‘get’ why a great heat exchanger is so important.

The article explains that at supersonic speeds, the air intake is compressed to such high temperatures that it melts the engine.

[Secret Agent Man]

yes, it is a very easy concept. in chemistry you learn

PV = nRT

where p is pressure, v is volume, and t is temp

you can rearrange to T = PV / nR

so when the pressure goes up temperature goes up. at scramjet speeds the incoming pressure is waaaaaay up.

they even make small portable piston based fire starters based on this principle.