I am having trouble getting my thermal turbojet to function in Interstellar with antimatter reactors in KSP 1.5.1, KSP interstellar, 1.20.15.2, in sandbox mode.

What I have observed is:

• it works for two fission reactors.
  • It does not work for the beam core antimatter reactor, specifically:
  • the reactor is powered. (has hydrogen and antimatter)
  • the reactor sees the radiator.
  • the reactor quickly overheats, and, last but not least:
    • the reactor tries to produce heat for the turbojet after overheating when I put its throttle to max, but the turbojet produces no thrust.

I've had this working in the past, using KSP 1.1, 1.2 and even I think 1.4 in the past, but it doesn't seem to work anymore. It's been over a year since I last played KSPi, but I am certain I had a setup like this working in the past.

Beam Core Antimatter Reactor will no longer function with thermal turbojet, its simply too powerfull and would evaporate it in an instant. Instead you could use the positron antimatter reactor, which is mend for this task and has about the same behaviour as the original KSPI antimatter reactor.

Beam Core Antimatter Reactor will no longer function with thermal turbojet, its simply too powerfull and would evaporate it in an instant. Instead you the positron antimatter reactor, which is mend for this task

Okay but how is one supposed to find this out? I spent over an hour working with antimatter power before giving up. Not having a clue as to why it wasn't working, as pointed out, I see inconsistent behavior: the reactor definitely responds to throttle action on the thermal turbojet.

There really should be a message to the user that this will not work, otherwise this is extremely confusing and disappointing.

Edit: Also, the reported temperature for the supposedly less hot anti-matter reactor is reported as being 500000 kelvin, whereas the one that is "too hot" is reported as 6666 kelvin.