SAS Prograde/Retrograde Not Working (only Stability Assist works)

[johns]

I've been using OKTO2's with all my recent ships, but when it seems that no matter what I select on the "direction selector", SAS just behaves as if "stability assist" is selected. I have plenty of RCS thrusters and fuel, and I can easily manually orient my ships, but SAS won't do it. Has anyone else run into this issue?

[Neywiny]

are you sure that you have a prograde vector? otherwise the selection won't work.

[johns]

are you sure that you have a prograde vector? otherwise the selection won't work.

Yes - I've had this problem during takeoff from Kerbin, while in orbit, and while coming in for a landing on the Mun.

[capi3101]

Making sure I understand the problem: you've got a craft with an OKTO2 probe core, SAS on, RCS off, and can't steer, is that right?

If so, then you should be advised that the reaction wheels were removed from the OKTO2 probe core in 0.90...you can't steer with one-of-thems alone. You'll either need to add one of the SAS parts to your craft or pick a different probe core to get it to work the way you want to.

Irked me the first time I tried to use an OKTO2 by itself in 0.90...

[johns]

Making sure I understand the problem: you've got a craft with an OKTO2 probe core, SAS on, RCS off, and can't steer, is that right?

I have RCS on, and I can steer manually, and SAS will hold the current heading, but it will not change my heading to go to prograde/retrotrograde/radial/etc.

[capi3101]

Okay...so it's not that you can't steer, but that for some reason the standard attitude autopilots for the OKTO2 aren't working at all, right?

You can steer manually, so you've got electrical power, you're not in timewarp and your craft is not too heavy for the amount of thrusters you're using; we can cross all of those off the list ipso facto. SAS on, RCS on, won't steer automatically...

Might be a bug with your local instance of KSP. I haven't heard of Squad changing SAS functionality to where it wouldn't use RCS on its own.

[jkool702]

I've had this exact same issue - SAS simply brings the craft to the wrong vector. Its not an issue of lack of SAS / reaction wheels, since you can still manually steer correctly. I also seem to remember it did a decent (but not perfect) job at holding the current heading, but prograde / retrograde didnt work at all. I dont know WHY this happens but can confirm its not an isolated incident in 1.0.4. I've also had a similar problem as this in 1.0.2, making me think this is a long standing bug.

I dont think this it tied to a specific SAS unit, as when this happened to me a lvl 2 Jeb was piloting and I didnt have SAS iirc. It also doesnt sem tied to RCS use, as I had RCS off (asnt even on this craft) and it still happened.

The only thing that fixed this for me was actually returning the flight to kerbin and recovering and launching a new flight. Resetting the game didnt work, but thankfully my next flight worked correctly.

EDIT: I also seem to remember that when I turned SAS off this craft would decide to pitch up and rollaround in circles for no reason whatsoever (like I was holding "s" only I wasn't). Dont know if this is a related bug or if that craft was just kraken bait.

Edited July 9, 2015 by jkool702

[Sharpy]

Same problem here.

http://forum.kerbalspaceprogram.com/threads/128168-Decoupler-Propulsion-Rocketry

Watch the video around 2:10 - I'm switching Prograde stabilization and I'm completely ignored - I need to keep stabilizing manually. Okto2, small reaction wheel, a plenty of electricity left.

[Daveroski]

I've been using OKTO2's with all my recent ships, but when it seems that no matter what I select on the "direction selector", SAS just behaves as if "stability assist" is selected. I have plenty of RCS thrusters and fuel, and I can easily manually orient my ships, but SAS won't do it. Has anyone else run into this issue?

Just so you know.

You were clear. Concise and to the point.

I had absolutely no problem understanding your question on the first read.

Pass it forward. People need to know. ;o)

[capi3101]

EDIT: I also seem to remember that when I turned SAS off this craft would decide to pitch up and rollaround in circles for no reason whatsoever (like I was holding "s" only I wasn't). Dont know if this is a related bug or if that craft was just kraken bait.

I've seen this - turn SAS off and your craft will sit there and spin like a top until you turn it back on again. Very annoying right after you've undocked something and it starts spinning. Could be a related bug.

[Claw]

Craft or save files would help, especially if they are all stock. Or even a picture. Then we might be able to see/replicate the issue.

Cheers,

~Claw

[johns]

Sorry I've been away. I've experimented and got a HECS ship where the prograde control works, and an OKTO2 where it doesn't.

Working HECS ship: https://drive.google.com/open?id=0B7lWO4AmTlw8bjJycGw4UHpJS0k

Not-working OKTO2 ship: https://drive.google.com/open?id=0B7lWO4AmTlw8ZlJOU1V4NlFhX3c

[Sharpy]

Craft or save files would help, especially if they are all stock. Or even a picture. Then we might be able to see/replicate the issue.

Cheers,

~Claw

The craft file and a video is linked in the thread I linked from my post. Steps to reproduce: Stage everything. The issue becomes apparent when the last stage flies free.

[johns]

Here's a direct link to the timestamp on that video where "prograde" is engaged, but behaves just like stability assist: https://youtu.be/--ORuY5qqsU?t=2m10s .

Note that for my ships, they're SSTO, so only the first stage has been engaged when the OKTO2 isn't working properly.

[PaleSaint]

Was this issue ever resolved?

[Bryant]

Not sure anyone every solved this, but I did an experiment as i was seeing the same thing with OKTO2.  I added a reaction wheel, and as you would expect it tracks now fine to prograde and such, did this with rcs on and off, no problems.  I even turned the torque off on the reaction wheel, and it tracks with RCS.  Seems like without a reaction wheel onboard it just doesn't do more than stability.

[Hotaru]

(Necroing this thread because it was the first thing that came up on a Google search for "KSP SAS not working.")

I just encountered a similar problem to the OP (though not specific to any particular part; it happened on two different vehicles with different command modules). Attitude hold appeared to work fine, other modes were ignored. The solution turned out to be that I had a joystick connected and it was apparently sending a tiny amount of control input which overrode the SAS. Jiggling it a bit seems to have fixed the issue. Just something to try for anybody having this problem in future who happens to run across this old thread the same way I did.