Thrust does not scale with different propellants when RealFuels is installed

[quantum1423]

When RealFuels is installed, KSP Interstellar's engines have the wrong thrust values. Essentially, no matter the choice of reactor, etc, the thrust is always fixed at a particular, arbitrary value.

The easiest way to reproduce this would be to get the CANDLE and turn it on. It always produces 4 kN in vacuum, no matter what type of fuel you give it, although the Isp does properly change.

This is more than a nuisance even though the wrong value is generally in the right order of magnitude, because MechJeb and other similar tools actually think that the maximum thrust is the correct value, when in reality it's stuck at, say, 4 kN for the CANDLE. This means that MechJeb starts burns at the wrong time, crashes probes attempting to use the landing autopilot, etc.

[sswelm]

From what I heard MechJeb does not work with correctly with engines with variable Isp and thrust. It assumes these values are always stable and only look at the the atmospheric curve

[quantum1423]

This is not an issue with MechJeb, although that was what I was expected early on. RealFuels prevents the scaling of thrust at all, and that's definitely wrong, and has absolutely nothing to do with MechJeb. MechJeb misbehaving is just a symptom of that: a lot of mods get confused because frankly, it's seems to be a bug in Interstellar.

Just install RealFuels and fuel the CANDLE with different propellants, then right-click to see the thrust. Without RealFuels, it scales properly. With RealFuels, the thrust is stuck at 4 kN. In general, the thrust value is stuck at the "default" value displayed in the VAB.

I think the incompatibility may be an interaction with the SolverEngines module, which would also explain the incompatibility with AJE, but I'm not sure.

[quantum1423]

Here are some screenshots showing the issue:
https://imgur.com/a/HqPe0