[support] BZ-52 Radial Attachment Point physics issue

[ravensierra]

KSP Version: 1.3.1 (b01891) x64

What Happens: BZ-52 attachment points that should be part of decoupled debris remain with the vessel (sometimes invisible) and contribute to floating point errors and vessel explosions.

Mods / Add-Ons: All Stock (screenshots have a few utilities installed but this issue is present in a clean unmodded install, with no mods used in craft creation)

Steps to Replicate:

1) Have radially attached 'stacks' in lifter stage that include the BZ-52 e.g.:

2) Decouple the first stage from the central stack

Result:

The outermost BZ-52s (attached to SRBs) do not fall away with the rest of the first stage. They remain locked in space relative to the vessel and accelerate with the vessel.

Sometimes the BZ-52s are invisible but reappear at random.

Lots of floating point errors appear and periapses vary by hundreds or thousands of kilometers when pitching/yawing etc the craft or unloading the craft.

Larger vessels ALWAYS disintegrate spectacularly at SOI changes, and sometimes when coming out of time warp.

Here the BZ-52s became displaced at about T+15s, and then resettled:

Unfortunately, I brought the whole SRB stage to 'orbit' with me:

Note Ap/Pe etc NaN

Fixes/Workarounds:

- Going through SOI change at 5x warp at least stops vessels disintegrating..

Other Notes/Pictures/Log Files:

Vessel large enough to explode at SOI etc: https://www.dropbox.com/s/5aqq3k19x8h97de/Spice Miner.craft?dl=0

Smaller vessel which exhibits floating point errors: https://www.dropbox.com/s/y27d01arb1a5cp8/Munbis IV.craft?dl=0

Edited October 29, 2017 by ravensierra
Added more info / pictures

[ravensierra]

Has anyone/devs got any input into this?

[OHara]

People eagerly try to give help here, so probably no-one recognized the problem you report.
Your example ships are complicated enough (300 parts) that people might not have time to debug them.

I flew your big ship through a couple SOI changes with no problems on the same version and build as you use.  The only thing I suspect is maybe an intermittent problem with auto-struts(?) because you use them quite a lot.

I see the problem with the smaller vessel, radial attachment points failing to drop away.  Inspired by a recent thread, I edited 'radialAttachmentPoint.cfg' to make "PhysicsSignificance=0" and that removed the problem.   I have no idea why that would help, but you might try that yourself, or read that other thread and dig back to find the history of that setting.  @Geschosskopf might be interested/amused to see this come up again so soon.

Edited November 23, 2017 by OHara

[ravensierra]

Thanks for the response OHara, I'll give that a shot and see how I get on.