I just came back to ksp after a long break and I'm having a problem with helicopter rotors, I'll skip to the end here and spare the details.
Using a fresh install of ksp 1.4.5, firespitter.
Whenever I use the FS copter rotor (using reaction wheels, FS steering disabled) as soon as I fly to 150 meters terrain altitude its like a switch is flipped and roll becomes...squirrely for lack of a better word.
149 meters terrain height everything is fine.
Installed atmosphere autopilot mod since I thought it was stock sas being weird and my heli flew even better,
I could do all kind of crazy maneuvers with it and the autopilot kept it rock steady...that is until I hit 150 meters radar altitude.
My question is this, What happens at that altitude?
Some notes on what I've learned:
Engines that use ModuleEnginesFX don't behave like this.
ksp 1.1.3 doesn't have this problem 1.2.2 onward does.