Phantom acceleration?

[Oiff]

I’m just wondering if this is still an issue caused by parts clipping?

I made a ship and conducted rendezvous over Kerbin but then quickly realised I didn’t have sufficient control to dock it so went back to the drawing board and edited the ship a bit giving it some more reaction wheels and RCS thrusters.  I had to clip the reaction wheels to fit them in.

Now when I try to rendezvous it is nigh on impossible as my orbit keeps changing without me doing anything.  I will set up a 10km intercept but by the time I get there it has increased to 150km.

 

Is this likely caused by me clipping the reaction wheels?  Otherwise the ship is almost the same as the previous iteration that worked fine.

[Cavscout74]

I've found if you are playing for a while without exiting & restarting the game, I sometimes get phantom forces building up that act like that.   I usually notice it when I jump to an existing interplanetary mission & it starts changing the orbit on me.

[Oiff]

Ok I’ll try the same ship again on a fresh load and see if it behaves itself.

[LordFerret]

15 hours ago, Oiff said:

I will set up a 10km intercept but by the time I get there it has increased to 150km.

This could happen from other reasons. When you set up the intercept and do the burn, is the ship aligned prograde or to the blue course target indicator on the Navball? When you perform the burn, just how precise is it?... at times and under certain circumstances, even a fraction of a second short or over would have such impact.

And if none of the above, perhaps you've discovered a new Kraken for v1.4.x? ... which I'm assuming is what version you're playing.

[wumpus]

16 hours ago, Oiff said:

 I will set up a 10km intercept but by the time I get there it has increased to 150km.

If this is happening during [non-physics] warping, any acceleration (phantom or not) should be ignored.  If it *is* happening during warping, it is likely an unrelated bug.  I suppose it is possible for clipping to influence the physics engine, but altering a warp course is rather strange.

[Oiff]

13 minutes ago, wumpus said:

If this is happening during [non-physics] warping, any acceleration (phantom or not) should be ignored.  If it *is* happening during warping, it is likely an unrelated bug.  I suppose it is possible for clipping to influence the physics engine, but altering a warp course is rather strange.

It happens without warping at all.

 

42 minutes ago, LordFerret said:

This could happen from other reasons. When you set up the intercept and do the burn, is the ship aligned prograde or to the blue course target indicator on the Navball? When you perform the burn, just how precise is it?... at times and under certain circumstances, even a fraction of a second short or over would have such impact.

And if none of the above, perhaps you've discovered a new Kraken for v1.4.x? ... which I'm assuming is what version you're playing.

Aligned to the blue target indicator.  The intercept changes after I have shut down the engines, it is like they are still on even though they aren’t.  Not 1.4 on this game as it was started quite a while ago with ongoing missions.

[OHara]

4 hours ago, Oiff said:

[Changing course while in orbit] happens without warping at all.

Recent KSP versions are pretty clean from phantom forces; I would not expect clipped parts to cause any forces until and unless you un-dock them from the main craft. 

The only guess I have is that the RCS is turned on, and while the SAS is using those thrusters to keep you pointed, there is a net sideways thrust.  Even then, 100km change in intercept within one orbit takes a noticeable amount of RCS fuel.

[Airdude]

I experienced this last night. Just put a science ship in orbit when the apoapsis starts rising around 100 m/s. I shutdown the engine, disengaged SAS, hibernated the probe core, but it still kept rising. I can’t remember exactly how I stopped the bug but I think timewarping fixed it. My guess is an experiment storage box clipped into an equipment bay caused it.

Edited March 19, 2018 by Airdude

[invision]

did jeb eat the beans again?

[blakemw]

I'm pretty sure part clipping can't do this because parts on the same vessel don't collide with each other, for the most part. And I have a test setup that self-destructs on the launchpad due to "clipping" (though it's actually due to too many connections to one part), this thing involves just sticking like 100 edge radiators onto one small part. Even this highly unstable contraption when put into orbit doesn't apply the slightest phantom acceleration - and given that it suffers from a lot of wibbliness (parts jittering back and forth) you'd expect it to apply a change to the orbit if that could be done by two parts tugging on each other. I'm happy to be proven wrong of course.

I have 100% for sure seen phantom acceleration from mods, particularly time-warp mods, I can't remember exactly which ones though.

Edited March 20, 2018 by blakemw

[cgjunk2]

I noticed what appeared to be phantom forces on the ground.  I had some of the basic fins clipped into the bottom of a large service bay on a lander.  Below the service bay was a decoupler, and the fins clipped into this slightly as well.  When landed, I noticed jittering on the decoupler, and the whole lander moved laterally on the ground in tiny little spurts.   This is on a stock 1,4,1 install, no mods.

Edited March 20, 2018 by cgjunk2

[Oiff]

As an update I have found that I can use the same ship fine when I have freshly loaded KSP.

 

I can only assume something builds up in memory after a while that causes this.

[Mark Kerbin]

I've had an issue with this for a while. That was until I realized I was throttling down during docking/ interplanetary stuff  with the ctrl key, and some how wasn't turning the engine all the way off.

Doh.

Its also possible that you have a issue with physical / rails timewarp conversions. Don't timewarp during a docking maneuver and see what happens. This can be aggravated by part clipping.

Never had an issue with part clipping tho so... idk man.

[Oiff]

Oh, yeh I normally shutdown with X when completing manoeuvres, I’ve been caught out with that one before myself.