v1.04 Reaction wheels and Engine gimbals do not agree on SAS direction.

[Meteo]

Has anyone run into this problem before?

When using SAS Stability Assist, it works normally if you are set to prograde.

However, if your SAS is set to anything other than prograde (normal SAS in an arbitrary position, retrograge, anti-normal, etc), then any reaction wheels including those on command modules will work normally, but engine gimbals will spin you toward the prograde position no matter what orientation you are in.

As a work-around when this bug happens to me, I can either orient myself without using SAS, or lock my engine gimbals in order to thrust and not spin out.

On ships this bug occurs on, I've tested locking out the gimbals on just certain engine types, but it appears to affect the gimbals on all engines at the same time of any type.

Mods I have installed: (nothing that controls the ship or changes physics)

ScanSat

RemoteTech

StageRecovery

HotRockets (& SmokeScreen)

I used to have FAR installed but I uninstalled it a while back due to performance issues (lag).

This is what my ship looks like that it is currently affecting. It has affected multiple launches of this ship: http://i.imgur.com/gxCw355.png

This is the .craft file: http://puu.sh/jehpi/557fb28edb.craft

This does contain parts from the RemoteTech mod.

Now just on a note, near the very top of this ship is a unmanned command pod in addition to manned command pods. I launched more ships that had that configuration and the problem did not affect them. It's just once an a while a certain VAB build of a ship gets the bugged SAS problem.

Here is another .craft of a vessel with the same command+unmanned modules and reaction wheel which is NOT affected by the bug: http://puu.sh/jehwx/e8a3a5b1d1.craft

Edit: After loading the craft that had this problem in the VAB and fixing the position of some solar panels that inexplicably explode on the launchpad, I saved it as a different name. After launching the newly-renamed vessel, I soon realized that it did not experience the SAS problem. Any more information I find about this bug I'll try to update here for others. Here's the renamed vessel that is almost exactly the same that does not have the problem: http://puu.sh/jekz4/98b6ff1377.craft

Edited July 27, 2015 by Meteo

[ColKlonk]

If you have more than one SAS wheel, they sometimes fight against each other and the ship never settles on assigned direction.

If I have more than one wheel, I'd deactivate all except the one closest to COG (Centre of Gravity), and disable RCS as well.

As KSP has an awful PID centering algorithm, I get around this by a single time acceleration step when the ship is on target, and step back to normal time again.

[Meteo]

Oh really ColKlonk? I never had a problem with reaction wheels fighting, but that's similar to my problem of the engine gimbals fighting them. I did try using time warp briefly after disengaging SAS and it did not help. Thanks for the reply, it sounds like the same class of problem.

[sebi.zzr]

Did you use RT flight computer?If you use it to execute maneuvers,when it finishes,it will set itself to "kill rot" and will conflict with stock SAS.