I need help fixing an orbit bug

[Flamingkerbal]

I put a probe in an orbit around duna. Right know the probe is connected to the fueltank and nuclear engine but when i decouple the engine and fueltank everything starts to shake a little when i move the probe.  The orbit suddenlychanges from a circular one to a straight line that just goes into duna and if a try to accelerate time it says i cant go over 1 speed while in an atmosphere even tho i am 210 thousand meters over dunas surface. 

Has anyone here expierenced this bug or knows how to fix it? Because i need help fixing this.

[paul_c]

What kind of probe, and what else is connected to it? Do you have a screenshot?

[OHara]

Also, the version of KSP might help find a solution,

and even if you have no mods currently, maybe some mod present involved in building or launching the ship left an effect.

(The symptom sounds similar to what happened in a previous version, when using the mod 'HyperEdit' to move a craft and then use a decoupler (thread link) when HyperEdit and KSP miscommunicated about whether the ship is 'landed' or not.)

[Flamingkerbal]

3 minutes ago, OHara said:

Also, the version of KSP might help find a solution,

and even if you have no mods currently, maybe some mod present involved in building or launching the ship left an effect.

(The symptom sounds similar to what happened in a previous version, when using the mod 'HyperEdit' to move a craft and then use a decoupler (thread link) when HyperEdit and KSP miscommunicated about whether the ship is 'landed' or not.)

I am playing on the latest version (1.11). I havent had mods on at all for the past weeks.

[Flamingkerbal]

1 hour ago, paul_c said:

What kind of probe, and what else is connected to it? Do you have a screenshot?

Here's the probe

 

It's not the best screenshot but it's what i have.

The probecore is a MTM stage.

[paul_c]

2 hours ago, Flamingkerbal said:

 The orbit suddenlychanges from a circular one to a straight line that just goes into duna

For an orbit to change that radically over Duna, it must have a ton of delta V or TWR or force or whatever. Is it stable on and off the (engine) power? Can you hold a position? Does it have SAS? Are the pitch/roll/yaw indications off the scale when you or the SAS is trying to turn it, etc?

What is the TWR? You don't need much for orbit changes, in fact the less the better if you can fit a smaller/lighter engine.

[OHara]

1 hour ago, Flamingkerbal said:

I am playing on the latest version (1.11).

There is a similar bug that appeared with that version.  There are reports on the tracker (link, link) but so far no solution or clear way to avoid it.  

[Flamingkerbal]

13 minutes ago, OHara said:

There is a similar bug that appeared with that version.  There are reports on the tracker (link, link) but so far no solution or clear way to avoid it.  

Thanks! Thats exactly what happened!

 

I hope squad fixes this soon

[Flamingkerbal]

42 minutes ago, paul_c said:

For an orbit to change that radically over Duna, it must have a ton of delta V or TWR or force or whatever. Is it stable on and off the (engine) power? Can you hold a position? Does it have SAS? Are the pitch/roll/yaw indications off the scale when you or the SAS is trying to turn it, etc?

What is the TWR? You don't need much for orbit changes, in fact the less the better if you can fit a smaller/lighter engine.

The craft has SAS and isvery stable and it can easily hold positions.

[OHara]

There is yet another bug-report of what seems to be the same problem (link) and it suggests a possible workaround. 

If you can still go back to the VAB or go to an earlier save-file and start that mission again, change the root part.  Use the Re-Root button in the upper left in the VAB, or main-keyboard '4'-key, to get the re-root mode.  Then click some some part in the probe above the one connected the de-coupler. The idea is to choose some substantial part, like the probe core, to be the root of the probe after it separates.

That worked for the specific example in the bug report, so it might work for you, might not.

Edited January 23, 2021 by OHara

[paul_c]

16 minutes ago, Flamingkerbal said:

The craft has SAS and isvery stable and it can easily hold positions.

Aaaaah ok it sounds/looks like a bug. I wonder if it is specific to a feature/design of that vehicle, or Duna.