[0.1.1.0] Maneuver direction indicator on navball drifts during maneuver, SAS pointing at maneuver results in failed burn

[Draradech]

KSP2 0.1.0.0.20892   -   Windows 10 Home 21H2   -   Ryzen 9 3950X   -   RTX 2080 Ti (Driver 528.49)

KSP2 0.1.1.0.21572   -   Windows 10 Home 21H2   -   Ryzen 9 3950X   -   RTX 2080 Ti (Driver 531.18)
 

Observed: The maneuver direction indicator on the navball drifts during maneuver execution. SAS pointing at maneuver results in  failed burn. Switching SAS to hold before the burn results in correct maneuver execution.

Expected: SAS pointed at maneuver results in accurate maneuver execution, ideally compensating for alignment errors (unbalanced craft, etc).

SAS pointed at maneuver:
before:

after:



 

SAS hold:
before:

after:

Edited March 25, 2023 by Draradech

[MARL_Mk1]

Can confirm this happened to me too.

[DaveLChgo]

Task:
Create and executing a maneuver node that will change the direction of the orbit.
 

Execution:
While in orbit create a maneuver node so that the direction of the orbit will go from clockwise to counter clockwise or vis-versa.
Lock SAS onto the 'maneuver node'  not prograde or retrograde.   This will in most cases put the rear end of the ship in a retrograde fashion.  And the 'maneuver node and retrograde node icons will be on top of each other in the nav ball.

Start burn at appointed time and watch in map view.

 

Result:
As burn is applied....  New orbit line will decrease as expected.  Orbit line will impact planet as expected.  Eventually the orbit line arc switches to the other direction as expected.  The nav ball retrograde icon flips and becomes the prograde as expected.    But the maneuver icon for whatever reason stays locked onto the retrograde icon instead of staying locked onto the maneuver heading.  This then causes the ship to rotate back onto the maneuver node and flip flop around as the ship continually rotates.  This of course destroys the task of reversing the orbit direction.

 

Please let me know if you need any further information.

DaveLChgo

 

System SPECS - 

Dell XPS 8950
12 Gen i7 12700 2.10 GHz
32 GB DDR5 RAM
512GB NVMe M.2  & 2TB 7200RPM SATA
NVidia GeForce RTX 3060 Ti  8GB
Windows 11  Ver 22H2

[Starhawk]

Overlapping bug reports merged.

[Bej Kerman]

SAS assumes you do not rotate at all during the maneuver, which is understandable as long as the devs have not yet implemented persistent rotation. You just have to make sure your ship isn't changing course during the burn. Just use stabilize SAS mode or engage timewarp for the duration of the burn.

[Draradech]

6 minutes ago, Bej Kerman said:

SAS assumes you do not rotate at all during the maneuver,

Exactly. This bug report is for the fact, that while the maneuver is supposed to have constant pointing, the maneuver indicator on the navball (and thus SAS in maneuver mode) is drifting.

[Scarecrow71]

I have noticed that while this happens on most craft, it is really exacerbated when the Poodle or Labradoodle engines are the primary thrust.  

[Draradech]

6 minutes ago, Scarecrow71 said:

I have noticed that while this happens on most craft, it is really exacerbated when the Poodle or Labradoodle engines are the primary thrust.  

That might be a side-effect of the lower TWR and thus longer burns (which increases the difference of the current orbit direction relative to the orbit direction at the node).
It is also more noticeable for burns other than pro- and retrograde, because you are directly changing your orbit direction (and not just velocity). This is the reason my example in the top post uses an inclination change.

Edited March 25, 2023 by Draradech