One omission from Spaceships 7 is the heat signatures produced by the drives therein. Here's my best attempt to extrapolate the values from known data, feedback welcome. I'm going to ignore paranormal technologies, for realistic and quasi-scientific designs:
- Jet engine: My guess is all jet engines should have the same heat signature (+4), which means yes, you can have a fusion-powered stealth bomber that stays in the air for years at a time.
- Solar Boiler: Same as fuel cell or solar panel (+4).
- Vacuum Energy Power Plant: Antimatter, fusion, and total conversion reactors all have the same IR signature (+7), giving this power plant the same IR signature is an easy decision.
- Laser Rocket: Same as HEDM rocket (+5).
- VASIMR Electric Rockets: I would assume this has the same heat signature as an ion drive, whatever that is. I guess there's no reason for it to be any higher than the power source?
- Plasma Torch: Same as Fusion Torch (+10).
- Solar Thermal Engine: No clear analog, but my guess is +4, since it isn't particularly powerful.
- Radioisotope Sails: Same as lightsail or mag sail (+7) seems like a reasonable guess, but this is so low-thrust that maybe it should be lower?
Areas of uncertainty: maybe the solar boiler and solar thermal systems should be in the same category as lightsail/mag sail due to the size of the required mirrors? Also: maybe fission air ram and fusion air ram should be higher because they're basically flying nuclear reactors? Is anyone more informed about these things than I am?