[alberth]

I was hoping this was going to be about eliminating the heat trail of a plane.

Then learned it’s just about rerouting a flight to climate zones that will less likely form a vapor trail.

[Tor3]

But there's no physics which can remove heat from a thermal engine, other than shifting the heat to the outside.

(Science fiction books would use "heat sinks" in their war space ships to try to hide the heat for a short while, but would eventually have to dump the heat somewhere. As heat sinks are basically just a huge mass.. not an option for airplanes.)