sas not doing it's job

[Mate_fin]

SO I played the game last in 1.1 and sas was fine no problem worked as it should and kept my rockets flying straight. When after many months I come into 1.2 and decide to launch a rocket I turn on sas and launch. And the rocket has no sas on or so it seems. before sas kept the rocket stable stopped the spinning worked all round as expected. now it acts like nothing is happening, doesn't correct (or if it does it's not helping) wont stop spinning rolling or anything of the sorts and makes the rocket give the ground an unpleasant explosive kiss. 

[Aegolius13]

You probably already know this, but you need a pilot in a command module, or a probe core.  This hasn't changed since previous versions.  (The probe core needs a CommNet link back to Kerbin, but that's not an issue at launch).

1.2 made it harder to fly un-aerodynamic rockets, so those are more prone to flipping in the new aero, even if SAS is working normally. 

What are you using to provide the SAS torque?  Gimballed engines are generally enough for launch.  But if you're using a non-gimballed engine like the Reliant, torque from your reaction wheels might not get the job done.  You could also try adding control fins or more reaction wheels.  

 

[DD_bwest]

is the green icon on the navball lit up to show that sas is on?     do you have a picture of your rocket so we can see whats going on?

[bewing]

Yup, need a pic and/or a craft file of this rocket. Because SAS actually works about 5 times better now than it used to. So something funny is going on with your ship.

[stickman939]

12 hours ago, DD_bwest said:

is the green icon on the navball lit up to show that sas is on?     do you have a picture of your rocket so we can see whats going on?

The SAS button is actually blue.

Also you engage it by pressing T, which is the default key binding for toggling SAS on/off.

Electric charge is also important, but unless you launch the craft without any that wouldn't be the problem.

And @bewing is right. If you could upload your craft to Kerbalx.com or dropbox.com (Kerbalx is much better imo) so someone could test it, that would be appreciated.  

[DD_bwest]

1 hour ago, stickman939 said:

The SAS button is actually blue.

Also you engage it by pressing T, which is the default key binding for toggling SAS on/off.

Electric charge is also important, but unless you launch the craft without any that wouldn't be the problem.

And @bewing is right. If you could upload your craft to Kerbalx.com or dropbox.com (Kerbalx is much better imo) so someone could test it, that would be appreciated.  

lol your right, im thinking of the RCS light thats green

[Champ]

Check that :

- SAS turned on

- You have electricity

- You are in full control of the ship (if manned : pilot in a control pod, if unmanned : commnet link)

[Gaarst]

13 hours ago, bewing said:

SAS actually works about 5 times better now than it used to.

More of an opinion than a fact. The damping on the feedback is worse than ever.

[steuben]

I'm going to add a fourth one to Champ's list.
- the right end is pointed to space. the navball is completely blue?

[Sharpy]

Also, probe cores require antenna anywhere but very, very near the launchpad.

As for SAS... it works WAY better now. It used to be: start turning in random direction, then after a while begin changing direction towards desired, at full power, then overshoot by half the navball and keep wobbling ten times before finally pointing it right. Never mind a craft with too much control authority, wobbling endlessly and using all monoprop.

Yes, SAS is still completely lousy if you try to maintain Retrograde on launch with probe core or pod pointed backwards. And Roll is still wobbly, despite Pitch and Yaw being stabilized correctly. But it's better by strides than what it used to be.

[Chiron0224]

It's important to remember what SAS is and what it isn't.

SAS is not:

Omnipotent.  It won't magically hold a poorly designed rocket straight.  It can only do so much

A control authority.  SAS won't steer the vessel if it doesn't have any means to steer it.  You still need reaction wheel torque, RCS, fins (in atmo), and/or engine gimbal in order to steer the ship.  SAS is autopilot, not a rudder.

A pilot.  The craft still needs either a pilot or a probe core.  In 1.2 the probe core needs a signal in order to work so you'll need to put an antenna on it.  It's very possible that if your probe doesn't have an antenna that your rocket will ascend for a bit and then suddenly go out of control as it no longer has a signal.  It's also worth pointing out the SAS is limited on some probe cores and not all probe cores have reaction wheels built in (see entry above about control authority).

 

SAS is:

Stability assist.  If you have means of controlling your rocket, it's built aerodynamically stable, fuel flows logically to maintain a forward COM, you have a probe core with appropriate SAS capacity or a pilot (specifically a pilot, not an engineer or scientist) then and only then can SAS keep it flying strait.

 

 

Also a picture of your rocket might help identify any design flaws.

[Tio Oly]

Hello there! 

Well, actually I was looking for a place to ask this, and this thread looks like a good place to start.

I'm having troubles to control my ships (Any ship, even the stock ones), and this issue never happened before (As long as I can remember).

I'm using KSP 1.2 and 1.2.1 x64 on a windows system, fresh install, no mods (Or modded, the effect is the same).

At launch with SAS active, the rocket (say... The stock Kerbal X) begins to yaw left (West), very slowly, and when the external tanks were emptied and detached, the rocket has moved now ten or twenty degrees to the left, and it can go on to fourty or sixty degrees.

Now, I started to make a "gravity turn",  and press the D key to yaw right (East). Now it's when it gets crazy...

The ship begins to yaw right, but at the same time begins to pitch down (South) and roll right... as a result of this, the "obvious" response would be to cancel the pitch by pressing  the S key to pitch up (North) trying to go back to the center again, well, the rocket now is pitching up, but also started to yaw left (West) again, So, Im at the center again but fourty to sixty degrees back to the left. And this continues on and on until you can reach a circular orbit. 

Another issue (More noticeable when the ship is in orbit), is this. Let's say you move your ship prograde and click the SAS button for Stability Assist mode. now, if you manually or click the SAS retrograde button. the ship will change direction and face backwards, but it keeps making a pendular motion four or six times before it reach a stable position ( I remember with version 1.1.3 or earlier. the ship turns and stop almost immediately).

And all this movements with the A,W,S,D, controls needs to be done with the "precise" or "fine tunning" mode, in the normal mode the movement is very hard and it's very difficult to put the ship on the right spot.

I've tried everything I know without any luck:
- Change the wheel authority of the command pod and the reaction wheels.
- Put some reaction wheels on top, (And/Or) bottom (And/Or) the middle of the ship and Change the wheel authority settings.
- Change the Actuation toggles and the Gimbal limits of the engines.
- Change the Actuation toggles and the Authority Limiter of the winglets.

And... nothing, if anythig only gets worse. Is this normal? Am I missing something here?

 

Maybe it's part of the new game physics and I need to read some documentation about it, and learn to do everything again?

Or do I need to make some adjustements somewhere in the settings?

 

I'm really hoping to get some help on this issues. And thank you for your time.

Edited December 2, 2016 by Tio Oly

[bewing]

1 hour ago, Tio Oly said:

Maybe it's part of the new game physics and I need to read some documentation about it, and learn to do everything again?

Or do I need to make some adjustements somewhere in the settings?

The slow veering in the aerodynamics is a bug, and maybe it will get fixed someday. However, it is clearly a very mysterious bug, so it may take a long time to find it.

The "coupling" in the input keys (where tapping a roll control causes a small yaw too, for example) is also another bug. And that will probably also take a long time to fix. But the fact that you find it hard to control by hand should make it no surprise at all that SAS also has a hard time controlling it.

The complaints about SAS are generally not bugs, though. The same SAS system has to control airplanes, rockets in space, rockets in atmosphere, and rovers on the ground. There is one small bug that is causing overshoots in some cases. Sometimes "rotation" mode clicks on too soon. But SAS does not promise to keep your ship perfectly on course when it is in Stability mode. You can always steer your ship by hand until it is close to the correct direction and then turn on SAS to finish making the turn.

So yes, with 1.2, SAS was changed a lot, and aerodynamics changed a lot, and there are definitely a few small bugs that got introduced, and you need to learn to work with what you have until it gets fixed/changed again.

Edited December 2, 2016 by bewing

[Tio Oly]

On 2/12/2016 at 2:31 AM, bewing said:

So yes, with 1.2, SAS was changed a lot, and aerodynamics changed a lot, and there are definitely a few small bugs that got introduced, and you need to learn to work with what you have until it gets fixed/changed again.

Yes, the game has changed... a lot!
 

UPDATE:

I was trying to discover what was wrong with my game configuration, And digging in my old notes I remembered one great MOD wich I used a while ago. and was uninstalled beacause (with 1.0 I think), you can launch your rockets just fine with or without it.
 

Well... surprise!

I just installed it again and now the steering of ANY kind of rocket it's so much better and stable. It works fine with KSP 1.2 and 1.2.1.

Man! thank you so much @ferram4, this is a life saver.

[DD_bwest]

i used to use that, but as of 1.2 there is no need with autostrut and the built in joint reinforcement