I guess it depends on the context, initially I was making comparisons to heat seeking missiles. In that context, one might use the radar absorbent materials to defeat radar guided missiles, but that trick just doesn’t work with heat, as you can’t “permanently” absorb heat the way you can other kinds of energy. If your vehicle is also generating heat, hiding that is quite difficult.
Agreed, that’s a great trick, except sometimes emitting less isn’t really an option if you need the afterburner to keep running. And in fact, being able to radiate that heat away quickly can be important to avoid parts melting. You can dump heat into the exhaust, but that isn’t always helpful. Leaving the only real alternative to just make something else emit more (a flare).
That is how heat works in general, but that has nothing directly to do with reflecting or absorbing IR.
I guess it depends on the context, initially I was making comparisons to heat seeking missiles. In that context, one might use the radar absorbent materials to defeat radar guided missiles, but that trick just doesn’t work with heat, as you can’t “permanently” absorb heat the way you can other kinds of energy. If your vehicle is also generating heat, hiding that is quite difficult.
You don’t need to absorb it, just emit less. Lower the emissivity and the at the same temperature it will appear colder to a thermal camera etc.
Agreed, that’s a great trick, except sometimes emitting less isn’t really an option if you need the afterburner to keep running. And in fact, being able to radiate that heat away quickly can be important to avoid parts melting. You can dump heat into the exhaust, but that isn’t always helpful. Leaving the only real alternative to just make something else emit more (a flare).