Change to RCS in 1.1.3

[Laughing Gravy]

I just installed 1.1.3, upgrading from 1.0.5. Just messing around, I notice that the RCS thrusters seem to fire non-stop while SAS is turned on.

In 1.0.5, I could, say, click on the retrograde button and the ship would turn to retrograde using RCS and any other attitude control available. When the ship was in the proper position, the RCS thrusters would shut down.

But in 1.1.3, when the proper attitude is reached, the RCS thrusters continue to fire pointlessly, draining monopropellant.

This is really annoying. Is this a defect, or is there a new configuration I need to perform to get the RCS to behave correctly?

Edited August 27, 2016 by Laughing Gravy

[Superfluous J]

41 minutes ago, Laughing Gravy said:

In 1.0.5, I could, say, click on the retrograde button and the ship would turn to retrograde using RCS and any other attitude control available. When the ship was in the proper position, the RCS thrusters would shut down.

I never experienced this phenomenon, with anything larger than the most extremely simple craft. Is it possible that in 1.0.5 you were new at the game and hadn't tried anything large yet, and now in 1.1.3 you're better at the game and trying your hand at more complex craft?

And yes it's annoying, but it's part of the game, at least for now. The best you can do at the moment is to just turn RCS off once it's done the bulk of the work getting you lined up, and let reaction wheels and engine gimbaling do the last bit.

[Crown]

A similar observation involves not RCS but electricity.

When I tell the craft to orient to prograde it will use more power to stay at prograde than telling it to go to prograde and then enabling attitude control (tapping "F" once). I think in the same way it uses RCS.

This might be due to the inaccuracies of the simulation. If I need to look at power I usually switch to "attitude control" after orientation is done. With some minor corrections just before the main event.

[Reactordrone]

I tend to find it happens more on small vehicles when using SAS settings other then stability hold. You can select the RCS units and adjust then to only fire for translation manoeuvres. That eliminates the problem since it tends to be a rotational oscillation caused by the reaction wheels.r

[swjr-swis]

The culprit is the current implementation of SAS: in most circumstances, enabling anything other than 'stability' mode, SAS basically never succeeds at pointing at the node you requested, instead entering an eternal state of correcting-but-never-quite-getting-there. This happens no matter the size of the craft, it is just less noticeable with larger craft.

Two workarounds for the wasteful monoprop usage: as stated by the others, you can manually disable RCS when you're close enough. Or you can rightclick tweak the RCS thrusters to NOT work for craft reorientation at all; let reaction wheels do that for you (but mind the EC usage, and SAS will still fail at orienting accurately at nodes), and use RCS only for translations. I feel the reaction wheel 'cheat' is currently warranted considering the game forces me to deal with untrustworthy SAS to begin with; dev notes give us some hope that 1.2 may bring improvement.

[GoSlash27]

3 hours ago, Crown said:

A similar observation involves not RCS but electricity.

When I tell the craft to orient to prograde it will use more power to stay at prograde than telling it to go to prograde and then enabling attitude control (tapping "F" once). I think in the same way it uses RCS.

This might be due to the inaccuracies of the simulation. If I need to look at power I usually switch to "attitude control" after orientation is done. With some minor corrections just before the main event.

This has always been present in my experience. "Prograde" doesn't stay in one place when in orbit, so SAS is constantly correcting. I have always parked my ships radial when in orbit to avoid this problem. It also males it easier to keep my solar panels exposed to sunlight.

Best,
-Slashy

[Laughing Gravy]

Thanks for the responses. I have experienced this on larger and smaller craft in 1.1.3. Switching off RCS right when I reach the desired attitude will have to do for now - and this is an ironic solution, since in previous versions, I would often leave RCS off until just when I was pointing at the node, then turn it on to quickly stabilize attitude, at which point it would shut itself down.

I do like to use RCS when I can to match orbital inclinations, which is hard to do if it's also firing in all directions as it tries to maintain Normal or Anti-Normal attitude. I'll have to fiddle with the settings to see what works best. I suppose each quad has to be adjusted separately? There's no universal RCS configuration?

6 hours ago, swjr-swis said:

The culprit is the current implementation of SAS: in most circumstances, enabling anything other than 'stability' mode, SAS basically never succeeds at pointing at the node you requested, instead entering an eternal state of correcting-but-never-quite-getting-there. This happens no matter the size of the craft, it is just less noticeable with larger craft.

Two workarounds for the wasteful monoprop usage: as stated by the others, you can manually disable RCS when you're close enough. Or you can rightclick tweak the RCS thrusters to NOT work for craft reorientation at all; let reaction wheels do that for you (but mind the EC usage, and SAS will still fail at orienting accurately at nodes), and use RCS only for translations. I feel the reaction wheel 'cheat' is currently warranted considering the game forces me to deal with untrustworthy SAS to begin with; dev notes give us some hope that 1.2 may bring improvement.

You know, after posting my message and playing with it some more, I began to suspect SAS. I noticed my engines also continue to gimbal wildly when at a node. Thanks for the tips. I hope it gets fixed. I did a maneuver burn and the engine was shaking like it was three espressos over its limit.

[Rodhern]

52 minutes ago, Laughing Gravy said:

.., I began to suspect SAS. .... I did a maneuver burn and the engine was shaking like it was three espressos over its limit.

Oh no, now you got me to notice it too! Never really played around a lot with the SAS, but letting Jeb try it out onboard a stock "Kerbal 1-5" just now, it seems you are right. Either Jebediah had three espressos too much, or the sneaky little monkey is imitating me playing KSP on a keyboard (flickering the key to get some sort of minimal 'average' control deflection, because I yet again forgot about the caps-lock controls).

[steve_v]

Stock SAS has been garbage forever, recently it got even worse. On a small craft the current "Pilot SAS" doesn't even get close to the selected heading, it just flails about wasting EC and/or monoprop indefinitely.
Come to the dark side, install MechJeb and SmartASS will point ships where you tell it to.

[fourfa]

MechJeb's SmartA.S.S. really is what stock ought to be.  Worth installing just for that module alone