I have mentioned cooling systems on space craft a few times in the Jack Mack stories, but never
delved into it. It was never necessary to the story. I have noted
that the heat is not generated from the thrust tubes in a typical
engine but by the force fields that contain their power. From a
practical standpoint, that comes to much the same thing and it is,
admittedly, not a tremendous amount of heat.
It is, of course,
difficult to dissipate heat in a vacuum. None of it flows out of the
the rear of the engines, as with a jet. Indeed, one can stand quite
close to business end of most thrust tubes (too close might knock you
down, or worse). Almost all engines do have a vacuum cooling system,
involving some sort of radiant heat dispersal via fins or the like.
This would be a back-up or auxiliary to normal cooling systems,
though small low-power engines might need nothing more (including at
least some maneuvering units).
Jack’s crippled W-4
he piloted into Thule Station had a very minimal vacuum system to
save weight and space. He could have limped along with it after his
main unit gave out, but coming out of jumps might have been
hazardous.
More robust main
systems are needed in most ships, involving the circulation of a
coolant. Even more so in atmospheric ships, which tend to incorporate
larger pumps to keep things circulating. Fans, too, though those are
useless in space!