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Phantom Acceleration after separation and docking of


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  • KSP Version: 0.1.1
  • Operating System and version:  Windows 10 Pro 22H2
  • CPU and GPU models: i7 7900k EVGA 3080 XC3
  • Description of the bug.  
    • Expected Behavior: When no throttle inputs are on, ship's trajectory should not change
    • Observed Behavior: Apoapsis is slowly increasing and periapsis is slowly decreasing. Orientation of craft does not seem to change this acceleration
  • Steps to Replicate:
    • Log, Save and Craft files: https://gist.github.com/mattdarveniza/5d7c0d180279471db40fc4f8fcf6b457
    • If launching the craft file:
      • Launch to orbit
      • Drop all stages besides the lander and command module
      • Separate the stack separator
      • Note that the separator _should_ decouple both sides but stays stuck to the lander, this is likely the root cause of the bug
      • Turn command module around dock ship to lander
      • Phantom acceleration! Could be due to the interference of the still attached stage separator, but even after undocking both vessels still experience phantom acceleration
  • A list of ALL mods.  If the list is long, please consider using a spoiler window: no mods
  • Other Notes / Screenshots / Log Files (if possible..): See above for files
    • Note that the stack separator was attached to engine plates on both ends. This was done for stability as struts are pretty whacky and broken in this version of KSP sometimes. I can imagine that can cause some pretty whacky logic on separation.
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  • 3 weeks later...

Can confirm… I’m suddenly seeing phantom forces operating on my craft. I have been ferrying fuel up to my interplanetary craft and after delivery I shut down the Interplanetary Craft (basically turn of RCS and SAS and make sure engines are deactivated…. And even turned off fuel flow to main engine and double checked the ship orbit stats) and then switch to my tanker and fly it into atmosphere to keep the place tidy… And suddenly I get a message that my Interplanetary Craft is heading for a crash. 

When I check on my craft I find the Apoapsis has shot higher and Periapsis is heading for the surface,


Then I notice that other craft won’t respond to auto control right. If I set it for Prograde it keeps overshooting like crazy… pulls back and overshoots the other way. Other craft don’t even seem to try to head for prograde but if I manually steer it works perfectly. Sometimes the sluggish craft will randomly explode. It’s really bizarre.


This phantom force bug happened to KSP1 back in the beta and the very same things happened then. It’s like there is something pushing on the craft at 90 degrees to the direction of flight.

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