Phantom Torques during eeloo intercept burn

[Cannibal]

Hi there,

I have a very strange observation that I am hoping has a physical explanation since it is very frustrating and I would like to fix my spacecraft to remove it (if possible).

What's happening is, I am in an orbit around the sun just outside of kerbin's orbit, and have matched inclination angles with Eeloo. If this is suboptimal that's fair but my intercept efforts from inside of kerbin's orbit were always being interfered with by the mun so I decided to remove that from the equation by just moving out of its sphere of influence.

I am now in the process of raising one side of my orbit to intercept Eeloo about 15 degrees after its orbit has crossed that of Jool, and during the delta V burn really strange things are happening that I can't explain.

I am using the Smart A.S.S. to hold the maneuver node under the reticle which works well, but as I increase engine power beyond 1/3 the ship will begin to pitch or yaw despite having symmetric thrust and symmetric weight distribution. Reducing thrust slightly allows the reaction wheels to keep up for a while but after a few minutes of burning I have to lower the power to 20%, then 15% then 10% and the Smart A.S.S. has more and more trouble holding the heading. Keep in mind this is a heading that should rotate about 1 degree/day since I am in an orbit only a little higher than kerbins around the sun.

Eventually even if I kill all thrust the spacecraft rotates uncontrollably by either the Smart A.S.S. or by me manually!

Now the really weird part. Suspecting this was a bug I did a quicksave then a quickload and guess what.... the forces are gone. The spacecraft can hold a heading again no problem.

The only mods I have installed are mechjeb and build tools, no custom parts or other wackyness. The vessel is two probes docked together, one as a stage to carry them to Eeloo the other for the trip back with kerbals eventually, they are rotated 180 degrees relative to one another each with a large gyro unit and a large probe computer. Originally I thought the problem was related to the gyros fighting each other but disabling one spacecrafts gyros does nothing. Locking engine gimbals also does nothing.

Please let me know what you think as this one really has me scratching my head.

Edited August 13, 2013 by Cannibal

[Johnno]

Now the really weird part. Suspecting this was a bug I did a quicksave then a quickload and guess what.... the forces are gone. The spacecraft can hold a heading again no problem.

You already answered your problem. Quicksave/quickload is one of the standard recommendations for solving phantom torque.

Phantom torque can come from various sources, anything from clipping parts to entering/exiting SoIs at timewarp. There's no "physical explanation" to the issue as you already yourself proved that it was a bug. Beyond that, to avoid it in the future, don't clip parts together, don't enter SoIs at warp, quicksave/load when it does appear.

[KerbMav]

don't enter SoIs at warp

Install Kerbal Alarm Clock - it can automatically slow down and stop (even pause if wished) on SOI changes or maneuver nodes.

[JCLindo10]

I, too am having this problem. My spacecrafts that I've sent out to Dres and Duna are experiencing phantom forces, and they only go away when I close KSP, and restart it.

[Claw]

I, too am having this problem. My spacecrafts that I've sent out to Dres and Duna are experiencing phantom forces, and they only go away when I close KSP, and restart it.

Hmm. Because this thread is a bit old, I would recommend starting a new one. If you can, include pictures of your craft or a save file and a bit more description about what you are doing or what is going on. Those things can help us figure out what is going on with your specific ship. Some things have changed in 0.23.5, and there are several things that could be causing problems.