Reaction Wheels Going Rogue (on a Minmus Rover)

[Hoshi]

Hello KSP Forums,

I have a peculiar problem with my Minmus rover. When it sits there on the surface, doing absolutely nothing at all with SAS off, the medium reaction wheel in its center starts to applying torque. The full list is:

• SAS off, reaction wheel set to:
  • Normal: pitches forward
  • SAS only: indicators show slight pitch forward, but no actual pitch happens
  • Pilot only: indicators show slight pitch forward, but is actually 100% pitch forward
• SAS on (stability assist mode), reaction wheel set to:
  • normal mode: nothing
  • SAS only mode: slight pitch forward
  • Pilot only mode: pitch, roll, and yaw all 100% engaged

All this happens without me touching any buttons other than turn SAS on/off and cycling the reaction wheel mode. If I leave it alone with SAS on and the reaction wheel set to pilot only, I'll start violently tumbling through the air smashing my solar panels when I hit the ground. What's even weirder is that at certain points during the tumble, the direction that the pitch/roll/yaw is torquing will switch.

I'm completely at a loss as to why this would happen, but I think it's a problem with Minmus. The exact same rover works just fine on Mun. Any help would be appreciated.

Tumbling in Action

https://steamcommunity.com/sharedfiles/filedetails/?id=1436930824

[bewing]

Welcome to the forums.

First guess is trim. Did you try Alt-X?

 

[FleshJeb]

Second guess is an un-calibrated joystick.

[Hoshi]

Eureka! It was the trim! Thank you, bewing.

For those reading this in the future, trim is a sort of autopilot feature where you hold alt + wasdqe to adjust all reaction wheels/control surfaces to bend a certain way constantly whenever you aren't manually controlling them. alt + x resets trim to zero. For planes flying through the atmosphere, this means you can get your plane to fly straight without constant minor adjustments.

I'm surprised that I'm just now learning about this after 402 hours of game time. Trim controls aren't in any tutorial or even in the key bindings menu; I had to google 'ksp trim' to find out about it.