Come back old ASAS - all is forgiven!

[carazvan]

For me on stock steam install now KSP/Parts/ folder contains 2 things: JetEngine and turboFanEngine each with 3 files in their folders ... is this normal for everyone?

[SkyRender]

Now this is much more like it!

I'm also suspecting from all the reports that something, could be a mod, could be a bad settings file, could be old parts lingering about the KSP/Parts folder, might be interfering with normal SAS operation.

The new SAS might be a lot of things, but it most definitely isn't a thing that requires constant input to maintain attitude. It's been pretty consistently doing that on all the test cases we did here, and there were a lot of them.

If the SAS isn't holding attitude properly for you, then it very well may be in a buggy state, because that is certainly not the intended behaviour.

First things first though, we need a proper baseline to compare different cases here. So how about we use the Aeris 3A spaceplane as a benchmark? It's easy to fly and it's got a few particular flight characteristics that are easy to spot.

So, the test is as follows.

* Launch a new Aeris 3A from the runway, set it at full throttle and try to maintain level flight.

* Do not adjust trim. On neutral trim, the 3A has a slight tendency to pitch down when the tanks are full.

* Climb out to 1000m altitude and verify that it's doing that. Let go of the controls and make sure this tendency to drop the nose is there.

* Ok, that's our control. If you've observed anything else at this point, something is already wrong with your game and you should be doing a complete reinstall.

* Now, let's test the SAS. From level flight, engage it with T and don't apply any input. Verify that it's maintaining attitude.

* If that didn't happen, then something is wrong with your game. Reinstall.

* Now, a few more tests. Apply some slight pitch up input without disengaging SAS. Pitch up to about 30° and watch the aircraft maintain the new attitude.

* If that didn't happen, then something is wrong with your game. Reinstall.

If you spotted something wrong by doing this test, please list all your mods if any, and check the KSP/Parts folder to see if there's anything in there (on a stock install it should be empty). Also, try deleting your settings.cfg file and running the game again. It's unlikely, but not impossible that a bad config would mess things up.

That should be enough to spot most cases where things are very obviously wrong. We can start with that for now.

Cheers

To test the issues some have reported with the SAS seeming to malfunction on anything but stock craft, I devised a clone of the Aeris 3A painstakingly built from scratch in 0.21. Tests thus far suggest that it behaves exactly the same as the actual Aeris 3A, so we can probably rule out the problem being that stock craft somehow are "special" outside of being well-designed.

[giltirn]

Now this is much more like it!

I'm also suspecting from all the reports that something, could be a mod, could be a bad settings file, could be old parts lingering about the KSP/Parts folder, might be interfering with normal SAS operation.

The new SAS might be a lot of things, but it most definitely isn't a thing that requires constant input to maintain attitude. It's been pretty consistently doing that on all the test cases we did here, and there were a lot of them.

If the SAS isn't holding attitude properly for you, then it very well may be in a buggy state, because that is certainly not the intended behaviour.

First things first though, we need a proper baseline to compare different cases here. So how about we use the Aeris 3A spaceplane as a benchmark? It's easy to fly and it's got a few particular flight characteristics that are easy to spot.

So, the test is as follows.

* Launch a new Aeris 3A from the runway, set it at full throttle and try to maintain level flight.

* Do not adjust trim. On neutral trim, the 3A has a slight tendency to pitch down when the tanks are full.

* Climb out to 1000m altitude and verify that it's doing that. Let go of the controls and make sure this tendency to drop the nose is there.

* Ok, that's our control. If you've observed anything else at this point, something is already wrong with your game and you should be doing a complete reinstall.

* Now, let's test the SAS. From level flight, engage it with T and don't apply any input. Verify that it's maintaining attitude.

* If that didn't happen, then something is wrong with your game. Reinstall.

* Now, a few more tests. Apply some slight pitch up input without disengaging SAS. Pitch up to about 30° and watch the aircraft maintain the new attitude.

* If that didn't happen, then something is wrong with your game. Reinstall.

If you spotted something wrong by doing this test, please list all your mods if any, and check the KSP/Parts folder to see if there's anything in there (on a stock install it should be empty). Also, try deleting your settings.cfg file and running the game again. It's unlikely, but not impossible that a bad config would mess things up.

That should be enough to spot most cases where things are very obviously wrong. We can start with that for now.

Cheers

Hi HarvesteR, here are my observations from performing the tests you describe:

Fresh install of KSP from Steam (deleted directory first), Windows 7, no mods or parts packs. I launched the Aeris 3A and leveled it out (did not touch controls to yaw or roll the plane). Left SAS off. Firstly I did not see the tendency for the plane's nose to drop - it stays very level but does want to seem to roll slightly in a clockwise direction and also yaw in the same direction (which may be induced by the roll). Even after first rolling the plane anticlockwise past the horizontal point, the plane continued to try to roll and yaw in the clockwise direction. Activating SAS and pitching up from horizontal to 30 degrees, then releasing the pitch control, the nose immediately bounces back down towards the rising velocity vector (much as it does without SAS active), before settling at around 25 degrees pitch. After every adjustment of direction, the SAS always bounces back slightly before settling - a behavior others have observed. The bouncing seems worse when making only small adjustments.

[giltirn]

For me on stock steam install now KSP/Parts/ folder contains 2 things: JetEngine and turboFanEngine each with 3 files in their folders ... is this normal for everyone?

Yes, me too.

[Tiron]

Hi HarvesteR, here are my observations from performing the tests you describe:

Fresh install of KSP from Steam (deleted directory first), Windows 7, no mods or parts packs. I launched the Aeris 3A and leveled it out (did not touch controls to yaw or roll the plane). Left SAS off. Firstly I did not see the tendency for the plane's nose to drop - it stays very level but does want to seem to roll slightly in a clockwise direction and also yaw in the same direction (which may be induced by the roll). Even after first rolling the plane anticlockwise past the horizontal point, the plane continued to try to roll and yaw in the clockwise direction. Activating SAS and pitching up from horizontal to 30 degrees, then releasing the pitch control, the nose immediately bounces back down towards the rising velocity vector (much as it does without SAS active), before settling at around 25 degrees pitch. After every adjustment of direction, the SAS always bounces back slightly before settling - a behavior others have observed. The bouncing seems worse when making only small adjustments.

Yeah, I just ran a Kerbal-X Launch just to test it. I used a Mechjeb unit to give me ascent path guidance on the navball, but flew manually (and STILL botched it by letting my attention wander), and noticed that while it WAS stabilizing, after I finished the initial ascent burn and let go of the controls, it wobbled back and forth on the yaw axis (functioning as pitch due to the placement on the launch pad) for awhile before settling in. It kinda seemed like the initial response was very gentle before getting harder and overcorrecting, eventually managing to null it out after several cycles.

What I think might be happening is not so much that it's failing to stabilize, but it's doing so rather slowly, and people are assuming it's not working and trying to correct it manually before it really does anything. Or it'll start to correct, and being very slow fine-tune adjustments when they get impatient and do it manually. And then you end up with the fine-adjustment making it seem like it's creeping.

Edited July 25, 2013 by Tiron

[Cipher29]

After doing quiet a bit of testing, strictly with aircraft, I can find no consistency whatsoever with how the SAS behave between craft. I've tried old planes, new planes, and stock planes, yet every time the SAS behaves differently. With some aircraft you can point to a heading and it will keep that heading just like the old SAS. With others however the SAS won't keep heading you started with but drift to the velocity vector and only maintain a certain attitude once the two meet. Even odder stuff happens when trying inverted flight: most of the time the craft will pitch towards the ground and the SAS will not apply any action to counteract this drift, despite the fact I could easily maintain attitude with some trim. It seems that a lot of the time the SAS is "underpowered" and isn't applying as much control as it could to maintain headings. Tomorrow I'll try some more tests with rockets and a fresh install and see if that fixes anything, but for right now the SAS varies on a case by case basis.

[DChurchill]

Yeah, I just ran a Kerbal-X Launch just to test it. I used a Mechjeb unit to give me ascent path guidance on the navball, but flew manually (and STILL botched it by letting my attention wander), and noticed that while it WAS stabilizing, after I finished the initial ascent burn and let go of the controls, it wobbled back and forth on the yaw axis (functioning as pitch due to the placement on the launch pad) for awhile before settling in. It kinda seemed like the initial response was very gentle before getting harder and overcorrecting, eventually managing to null it out after several cycles.

What I think might be happening is not so much that it's failing to stabilize, but it's doing so rather slowly, and people are assuming it's not working and trying to correct it manually before it really does anything. Or it'll start to correct, and being very slow fine-tune adjustments when they get impatient and do it manually. And then you end up with the fine-adjustment making it seem like it's creeping.

I did an absolutely fresh install with no mods and this was my experience. I can see RCS trying to stop the creep, but isn't successful. It also seemed to bounce back and forth in both pitch and yaw for me. It would settle, but back to where I started before trying to correct it. You can't make small little taps to correct it and have it stick.

[Fleb]

I did a quick vid with the 3A on a stock install, new save. The only thing I noticed, is a bit of drift after manual input.

http://www.youtube.com/watch?v=busbXdu5gDU

[Brabbit1987]

I did some of my own tests, both rockets and planes. It is working perfectly fine on my end. Though I do have to mention, as an example, I pitch the planes nose up by 20 degrees and it will drop back down 10 degrees, or something like that. I actually find this works fine and have gotten used to it pretty quickly as I remember playing flight simulators with similar behaviors. I used my controller, and I must say, I flew an airplane in the cockpit the whole time with perfect control, landed after about 10 minutes. I then took off again, and landed back at Kerbal Space Center. Perfect landings each time. Just so we are clear, past versions I pretty much always crashed. So this is a huge improvement.

As for rockets, steady as can be. I was easily able to get it into orbit.

No mods, all stock parts. Fresh install.

[Cipher29]

I just noticed something very odd with the Aeris 3A test, if I pitch up 30 degrees, full throttle, SAS on with precision controls off it will bounce down to 25 degrees but slowly climb back up to 30 degrees. If precision controls are on however it bounces down to 25 degrees and stays there.

Precision control seems to affect how the SAS locks on headings, people should indicate whether they have it on or off from here on out.

Edited July 25, 2013 by Cipher29

[regex]

Fresh install of KSP from Steam (deleted directory first), Windows 7, no mods or parts packs. I launched the Aeris 3A and leveled it out (did not touch controls to yaw or roll the plane). Left SAS off. Firstly I did not see the tendency for the plane's nose to drop - it stays very level but does want to seem to roll slightly in a clockwise direction and also yaw in the same direction (which may be induced by the roll). Even after first rolling the plane anticlockwise past the horizontal point, the plane continued to try to roll and yaw in the clockwise direction. Activating SAS and pitching up from horizontal to 30 degrees, then releasing the pitch control, the nose immediately bounces back down towards the rising velocity vector (much as it does without SAS active), before settling at around 25 degrees pitch. After every adjustment of direction, the SAS always bounces back slightly before settling - a behavior others have observed. The bouncing seems worse when making only small adjustments.

Confirming this behavior from a completely clean install from Steam. I blew out the directory before reinstalling.

The exact same thing happens during rocket launch: you must massively over-correct because the SAS (or the craft) swings back towards the original heading once you let go of the controls instead of accepting the new heading. Having it correct itself to the new heading would be perfectly fine behavior but it's as if the SAS simply doesn't want a new heading. Toggling the SAS (I thought not having to do that was a big feature of the new code) helps to put the rocket (or plane) onto the correct new heading.

Making small corrections in orbit is incredibly frustrating because the SAS wants to return to the original heading. Once again, if I twitch it using "F" or toggle it off and on again it accepts the new heading.

If the rocket is even slightly unbalanced, the SAS will only hold it on course to a certain degree; it will drift a bit until the SAS regains control and then remain at a slightly "off" heading until the burn is complete, at which point it will return to the original heading.

You can replicate the above rocket behavior by putting a small craft into orbit that is slightly off balance, like this one:

I have more than enough control authority to throw this thing all over the place during a burn without using RCS, the SAS should have no problems at all keeping it on heading, but it always heads slightly off during a burn.

Edited July 25, 2013 by regex

[giltirn]

I just went out flying the Ravenspear Mk4. On this plane the bounceback upon releasing the controls after changing direction is less harsh than on the Aeris 3A. One thing I did observe: when you adjust the pitch, the control surface angle changes to about 30 degrees. With SAS on, releasing the pitch control causes the control surface to reset its angle to zero before slowly climbing back to its original angle again. What I think is happening is that the SAS sets the trim to maintain a fixed direction. It seems that it always resets the trim to zero prior to performing its adjustments, irrespective of the initial angle of the control surface when the player releases the control.

[Sapphire]

Okay, so I ran some tests with a probe in orbit around Mun and ran it through some orientations and basic maneuvers to find out a few things. The craft is a symmetrical probe with an OCTO core, a 1.25m inline reaction wheel, and a 1.25m advanced stabilizer.

1. The SAS doesn't utilize your craft's full gyroscopic potential. I turned off my RCS for this and pointed it in a couple directions, then I sent it into a slow spin and stopped it manually, then I sent it into a slow spin and stopped it with SAS. Result: SAS stops it much, much slower. It doesn't use the full power of your reaction wheels.

2. SAS won't return it to its original orientation.

I set up a maneuver node, then spun slowly.

When passing over the maneuver node I hit T (and the screenshot button).

It slowly came to a halt, started to move back,

then stopped here permanently, quite a ways off from the original node. I wasn't using WASDQE at all, so it stopped at its own accord. Which means that if gravity, thrust, etc. moves you off your node, SAS won't bring you back, so you constantly have to be doing adjustments to stay on the node.

My question: Is that working as intended?

[giltirn]

I just noticed something very odd with the Aeris 3A test, if I pitch up 30 degrees, full throttle, SAS on with precision controls off it will bounce down to 25 degrees but slowly climb back up to 30 degrees. If precision controls are on however it bounces down to 25 degrees and stays there.

Precision control seems to affect how the SAS locks on headings, people should indicate whether they have it on or off from here on out.

I cannot replicate that behavior on the Aeris 3A or Ravenspear Mk4 - in both cases the 5 degree bounce-back occurs after a 30 degree pitch adjustment.

[Cipher29]

I cannot replicate that behavior on the Aeris 3A or Ravenspear Mk4 - in both cases the 5 degree bounce-back occurs after a 30 degree pitch adjustment.

So its just a bug on my end then? Everyone seems to be getting different results right now

[Nexustrimean]

Just a Minor Curiosity, were any of you using physics warp before this happened? Even in another flight?

[Cronos988]

Report from testing the Aeris 3A:

- On launch, has a slight tendency to veer off runway.

- Rolls slightly left (or counterclockwise) when climbing, nose pitches up as a result.

- after correcting the roll, maintains level flight with the nose pitching slightly down, as expected.

Now engaging SAS:

- Holds level flight

- Upon pitching up, bounces back about 5° for every correction. Trying to move the nose up 5° does almost nothing (bounces approx. 4 degrees back down).

- after the slight bounce-back, it holds the new attitude perfectly

- corrects rolls very sharply, positively "locking" the craft in roll.

- Does not accept any change in the yaw axis. It immediately bounces back, only allowing me very very slight yaw corrections.

Edit: Upon further testing, "locking" the roll and bouncing back immediately from any yaw correction seem to be natural features of the craft, not specific SAS effects. SAS does indeed make the yaw more manageable, as the craft will not overcompensate any yaw input as it does without SAS.

Edited July 25, 2013 by Cronos988

[boxman]

I have been trying for hours just to break the new ASAS/reaction wheels and it just dosent happen for me. I have been making several spaceplanes and now just finished a trip to duna using my regular aspargus mainsail lifter.. Again it keeps heading just fine and never goes out of control.

Really odd how this only seems to affect some people.

[Tiron]

I went and reinstalled cleanly, and ran a kerbal-x up to orbit fully manually. The behavior was almost the same.

My observations:

On Torque-Only craft with high mass relative to their control forces, the new SAS system is *extremely* slow to stabilize a gross movement. It initially tries to fine correct it, and brings in more control force gradually as that fails to do anything. This is pretty much how it's supposed to behave, it just doesn't work very well on a craft where you need full force to initiate or stop a movement of any significant rate. It seems to take the new SAS system awhile to realize that the small inputs aren't actually doing anything and go to full power...and then it does the same thing AGAIN when it gets back to where it's trying to hold. This causes it to bounce back and forth before gradually settling in and stabilizes. On something like the Kerbal-X core at 40KM+, where the fins do basically nothing, this can take 10-15 seconds for a gross movement to be nulled.

The top stage demonstrates the same problem, to a lesser degree: I've got it on orbit with a bit under 2/3rds fuel...and may have found the problem.

If I hold one of the yaw controls down until I've rotated about 45 degrees, it takes a further 90 degrees to stop. When it does stop, rather than rotating around to the point where I let go of the button, it rotates it around 1-2 degrees, to a point very near where it stopped, and stabilizes there.

Is the Pod SAS still just acting a movement-damper and not a direction-hold because it lacks an Integral Component, like the old ones did?

Going to add the renamed ASAS to it and relaunch.

[boxman]

I just noticed something very odd with the Aeris 3A test, if I pitch up 30 degrees, full throttle, SAS on with precision controls off it will bounce down to 25 degrees but slowly climb back up to 30 degrees. If precision controls are on however it bounces down to 25 degrees and stays there.

Precision control seems to affect how the SAS locks on headings, people should indicate whether they have it on or off from here on out.

It works fine here and I am not using any precision controls.

[Umlüx]

i miss the old ASAS already. sure it was way to overreactive, but it held the plotted course. i have flown some manned and unmanned missions since the update and the ships are always drifting.

even on ascend my rockets are slowly tipping over and i have to correct it manually.

well.. waiting for MJ SmartASS...

[KOCOUR]

Guys who hate the new SAS, i thing you have the same problem iam having with all new stuff and changes. It is called getting use to, or Figuring out how to. I bet in short time most of you will figure it out and it will work for you.

I had this problem when they introduced maneuver nodes. they didnt work for me and confused me, before i figured out how they work. now i love them. I had this problem when i first time tried out mechjeb (i had to do randevouse and docking and interplanetary transfers manualy, before i figured out how to work with mech jeb, now mechjeb is doing all randevouse and docking for me allright. i still have to do some manuall interplanetary transfer trajectory adjustments, but mj is doing most of the work now.)

So give it time, play with it a little, and i thing it will just get better.

Iam really looking forward to when i come home from work and try it out for my self, and i bet i will have the same issues as you do, but i allso bet that i will get the hand of it.

Edited July 25, 2013 by KOCOUR

[SkyRender]

For those of you still having SAS issues, try these tips:

* Make sure your rocket/spaceplane is as balanced as possible; that means more than just symmetrical, it also means nothing bulging out excessively and a decent balance between centers of lift, thrust, and mass

* Put reaction wheels, winglets and RCS on your rockets; the new SAS requires some form of control method to work properly, and gimballing is often not sufficient

* If it's not balanced in space, it's going to drift off center; make sure whatever's actually ending up in space is also fairly well-balanced between thrust and mass

[Tiron]

i miss the old ASAS already. sure it was way to overreactive, but it held the plotted course. i have flown some manned and unmanned missions since the update and the ships are always drifting.

even on ascend my rockets are slowly tipping over and i have to correct it manually.

well.. waiting for MJ SmartASS...

Mechjeb's been updated.

As for now, my all stock reinstalled steam version, with the Kerbal-X upper stage, is exhibiting the same behavior with the large ASAS added on.

It's starting to try to damp the movements almost immediately, but not at full rotational power: It starts slowly and ramps up, and then as it starts to slow (long before it's stopped), it starts to ramp down. It eventually stops at a point around 90 degrees past where I let go of the controls (a little further with the large ASAS, presumably because of weight), and then holds that position.

There seems to be some kind of error in what it's setting as the attitude to hold. The ramp down as it approaches the point where it stops suggests that it's actually aiming for that point almost from the moment you let go. What I'd expect to see is that it would ramp up to full almost immediately, hold until it started to rotate back towards where you let go, and then exhibit the behavior it's currently showing as it approaches that point.

This error in setting the hold attitude seems to show up for small movements too, causing the SAS to start pushing it off the point where you set it at, as it tries to reach the erroneous setting.

Edited July 25, 2013 by Tiron

[Vanamonde]

This test ship

has cabin torque, both versions of the inline thingy, canards, and a gimballed engine, but just coming straight up off of the pad with no input from me, this is how quickly and severely it wanders from its heading.

Now, am I misunderstanding something, or are all those control devices combined not supposed to be enough to make a ship this size fly straight?

For the record, it was built in a fresh download of 21 and not carried over from a previous save, and I have no mods installed. SAS mode is on with T, and I tried tapping F, which made no difference. I tried the design with each control piece type separately, and then combined them; NO permutation of control parts can hold a heading, though some deviated more slowly than others. When watching the ship zoomed in, I can't see the engine pivot at all, and control surfaces only move slightly.