Vehicle Attitude Persistance Issues

[natsirt721]

I think I may have found an issue with the way that vehicle attitude is persisted, but I have an old version of the game and a modded install so I'm going to spell out my test case and see if 1) it is actually a bug and 2) ask that someone attempt to duplicate the test case and see if it is actually a bug.

Situation

I have placed a vehicle in a 30 degree inclined Mun orbit at 55x57 km. I set the camera to ORBITAL, and align it so that Kerbin is in my field of view. I crank the time warp up to 1000, and as expected, the camera remains fixed to the attitude of the vehicle. However, as time passes Kerbin remains in the field of view of the camera.

Problem

I would expect that in this case, Kerbin would drift off the left edge of the camera plane, and eventually return on the right side of the plane sometime less than one Munar orbit later. The attitude of the vehicle should remain fixed in inertial space, and the camera, being fixed to the attitude of the vehicle should remain pointed at the same location on the skybox. However, by following Kerbin, it seems that the camera is rotating with the orbit of the Mun, and thus the vehicle is also being rotated in the same way. As the vehicle's attitude should remain the same w.r.t. inertial space rather than the local space of its parent body, this appears to be a bug.

Help!

If someone can reproduce this in an unmodded game on the latest version, then this is probably the result of one of my mods causing the issue - likely Mandatory RCS's persistent rotation feature. I did disable the feature and restart, and while I did observe the same behavior it may be making further-reaching changes that the feature toggle affects. 

[OHara]

For craft in relatively low orbits, KSP uses a frame of reference that rotates with the body being orbited, so Foucault pendulums don't work properly, for example. I think the dividing altitude might be the same one as used to distinguish science results from "in orbit, low" versus "in orbit, high".  55km above the Mün is a 'low orbit'. The Mün is tidally locked to Kerbin, so the frame of reference for low orbits around the Mün would keep pointing at Kerbin

 

[natsirt721]

Thanks for the reply, I figured something like that was going on. Kinda frustrating that the altitude extends so far up, as you can't really have anything stationary at that altitude given the limitations of the game engine. Also doesn't look like there is a way to modify that without recompiling, so I guess I'm going to have to boost my altitude a bit so I don't run out of power every 3 days.