Clipping issue? Solar panels freaking out

[wolowizzard666]

Hi guys,

I have quite some problem and don't find a solution through googeling, maybe one of you got an idea.

If I built a space station, adding docking ports and attaching a solar panel construction to it, those docked part groups are totally freaking out (pictures below) when I load a savegame in which the station exists. It does not happen when the panels are still retracted, only if I extend them, save the game, load the new save game and go to the station.

It does not help to reset the gyro, the cubes that were controlling the solar panel beams when docking are in hibernation, RCS is off, there are no reaction wheels attached that could cause the spinning, deactivation SAS does not help, and the rotation is unstoppable if switching to the detached parts.

If have the following Mods: MechJeb, EVE, Kopernicus Planetary System Modifier, ModularFlightIntegrator, Planet Shine and it's default configuration, Scatterer, Stock Visual Enhancements: Scatterer Configs and SVE High-Res, Stock Visual Terrain High-Res, TextureReplacer.

If you got any questions or ideas, I would be very thankful for any input on how to solve this. Next I'll try rebuilding the solar array construction, maybe with other structural parts, but I find this construction quite appealing, so solving the problem would be preferrable :-D.

Thanks in advance!

[Gianni1122]

@wolowizzard666

If it is a bad interaction with a mod, I personally can't help (mechjeb is the only one we have in common). But if those are your only mods, it doesn't seem like those would cause this issue.

Some things you might try:

-In the settings menu turn on "advanced tweakables" then when right clicking on various parts you should see an option for "rigid attachment".

-In the debug F12 menu there is are options for part clipping, unbreakable joints and non-strict part attachment.

-Maybe try using something other than the structural beams (the four larger ones) or put the 4 ports directly onto the cupola module.

-You could use KIS/KAS to attach the solar arms directly without using docking ports. You could also use this mod to add struts while in orbit. *this may actually be the best solution since struts might just fix the problem.

[Zhetaan]

It turns out that I had the same problem on my own station; however, I was using Gigantors attached to M-200 I-beams.  These were hard-attached to the station, so it's not the docking ports.  I have a different mod load from you, but you're only using visual mods (except MechJeb) and they wouldn't cause this.  MechJeb isn't suspect unless you are modifying the MechJeb parts or if this is happening while it's trying to control a manoeuvre.

Therefore, it's a clipping issue.  What I do not know without checking your logs is whether the clipping is panel-to panel (in which case you need better spacing between panels), panel-to-mount (in which case you need to mount the panels on some other part of the structure), or panel-to-opposing panel (in which case you need to stagger the panels on opposite sides of the structural beam).  Incidentally, I forgot to do this with my own save when it happened, so I have no logs to share, but your problem tickles my memory, so I took it upon myself to do a bit of research on the issue.

The more advanced solar panels can be tricky because they track the sun, which requires some more complicated collision boxes to account for their motion.  In cases where they are placed too close together, these collision boxes begin to interfere, but because the speeds are so low, they merely bounce or slide off one another.  However, the panels are still trying to occupy the same space and the tracking motors will continue trying to force this to happen, so this constant effort to clip through one another can set up unstable vibrations.  Given time, they can build a destructive resonance and shatter.

The only way I know to find out for sure is to let them shatter and then look at the log to find the cause of the panels' destruction.  It will tell not only that they were destroyed by collision, but also what they collided with to cause that destruction.  If it's another panel, then it's a spacing issue.  If it's the beam, then you need a completely different design for your superstructure.

That being said, it ought to be obvious that visually, the panels don't interfere.  Therefore, either the collision boxes are larger than the visual textures or there is something else going on.  I'd be interested in seeing whether radiator panels do this, too, so I could know whether it has to do with parts that track in general or just solar panels specifically.

Searching the bug tracker yields this.  Unfortunately, the bug listed sounds to be a very good reproduction of our problem, but it is listed as a duplicate and was alternately posted in the prerelease (which is now closed).

I also found this.  Click it if you want to see your problem writ large (for my part, I think having that many Gigantors waving in space is reminiscent of sea anemones; there's a linked video which makes it look like something more Lovecraftian); however, the report is seven months old and may need to be updated.  Regardless, if you create a clean install of KSP, duplicate your station (it's easier for you than for me because I have mod parts), and create a save that documents this problem in reproducible fashion, you may see it fixed for the next release.

As far as fixes for now are concerned, it appears that the issue arises only when loading a previously-saved craft with deployed panels.  If you want to make craft that go up, complete a mission, and return in a single playthrough, that should avoid the problem.  Obviously, that's no good for a station.  A solution regularly offered is more struts, but that does not appear to work reliably.  Another I found is to add parts to the station in order to change the resonant frequency, but that really only works on stations that have not been saved with deployed panels and in any case does not fix the clipping issue; it only makes it less totally destructive.  The only way I've seen so far to really avoid the problem is to rethink your solar panel placement methodology.