[Spaceships] Detecting hot reactionless

[Rupert]

Currently I use +6, so that a ship using standard thrusters (also called 'cold' in my campaign) and a non-nuclear power plant is noticeably stealthier. This is also high enough that hot thrusters are not stealthy (unless you're accelerating towards the sensor), while cold ones powered by solar panels or fuel cells are. It also makes using an old fission reactor slightly stealthier than a fusion plant, because the drives are less obvious than the latter.

It's not unknown for navies to have a few ships that have a cold thruster for low-signature manoeuvres and a fission plant and sometimes even a solar panel array just big enough to run the thruster. These are intended for quietly moving into low traffic systems to have a look around. Naturally such a ship has the Stealth and Dynamic Chameleon options, Enhanced Sensors, etc.