How to prevent SAS from using RCS?

[Sharpy]

When the craft is big, SAS behaves reasonably, at least in Stability Assist mode. But I got some quite small crafts that use rather strong RCS (Vernors) and if I activate both SAS and RCS it's less than minute before my fuel is all gone. SAS just keeps wiggling the craft around, even in precision mode (and even worse, in that mode no plumes of gas are visible, so I don't know my fuel is leaking unless I watch the resources window).

I could really live without SAS ever touching the thrusters. It does a really lousy job of it anyway.

Are there any mods, config tricks or other methods to achieve that?

Edited August 4, 2015 by Sharpy

[Tatonf]

Try to disable the gimbal of your engines (right click on them). Sometimes they are causing the wiggling.

[Sharpy]

haha. The craft in question has no engines at all, gimballed or not. Only RCS.

Tricky part is it's *slightly* asymmetric. Just one parachute missing on one side.

[RainDreamer]

Looks like you are trying to land an asteroid, from what I assume you intend to do with that craft.

As for your question, I sadly have no better answer than just...turn off RCS.

[xtoro]

MechJeb's SmartRCS option can disable using RCS for rotation, so only reaction wheels will turn you. But it will still use RCS for translating which is a great way to save monoprol/fuel for docking.

[Sharpy]

Looks like you are trying to land an asteroid, from what I assume you intend to do with that craft.

As for your question, I sadly have no better answer than just...turn off RCS.

Not asteroid, just all kinds of cockpits and cabins, including MK3. I bring 6 or so of these into LKO in one batch, and it takes me maybe 10 minutes for a "save from Kerbin orbit"... or it would if not all the games with "switch SAS off, activate RCS, perform burn, deactivate RCS, activate SAS to stop rotation..." the out-of-balance version was really a pain in the neck. Just one single parachute... other versions meant for different orbits/locations behaved fine.

[ajburges]

That's quite a module lander. My current version lands Mk3 tanks at less than 11m/s with 2 chutes and no airbrakes.

In stock, the only way to minimize RCS use for rotation is to toggle it and/or place thrusters with minimal attitude control.

[xtoro]

That's quite a module lander. My current version lands Mk3 tanks at less than 11m/s with 2 chutes and no airbrakes.

In stock, the only way to minimize RCS use for rotation is to toggle it and/or place thrusters with minimal attitude control.

In stock, you can do it. To clarify minimal attitude control: place single Vernor engines, or the single place-anywhere RCS thrusters centered with your CoM on all 6 sides and they will only be used for translation because they will not rotate your ship, so KSP won't use them for that. He also asked for mods that do this which is why I suggested MechJeb.

[ajburges]

I mentioned stock only approaches since those are the only ones I know of. They are also available no matter your configuration.

I stopped caring about the issue once Docking Port Alignment made my docking manuvers 10x more efficient. I always keep dedicated engines for KER displays.

Knowing that MechJeb can disable attitude thrust for RCS may just tempt me to the dark side there though...

[Sharpy]

That's quite a module lander. My current version lands Mk3 tanks at less than 11m/s with 2 chutes and no airbrakes.

In stock, the only way to minimize RCS use for rotation is to toggle it and/or place thrusters with minimal attitude control.

Better safe than sorry, besides it's not like it costs me much. Brought to orbit by SSTO, recovered after deorbiting, the only losses are the fuel, the percentage on distance from KSC (and with the airbrakes I can usually get within 90%) and a couple dumb struts and beams of the "base" on which they are sitting in orbit (only so that I'm not cluttering my map, one object instead of 6 or 7)

Though I admit the big parachute is an overkill. My new batch got Spark engines on stack decouplers, and are fully symmetric. (the parachute on the side was missing to provide room for a radial separator, as you see they are quite packed and there was simply no room to attach them radially.)

[Wolfox]

I suggest adding few classic monoprop maneuver nodes, and designate vernors to a group as "toggle on/off". This way you can use vernors only for propulsion to encounter debris/whatever you want to bring back home and deorbit, and maneuver jets for fine control to catch up the debris or stabilize the craft. When toggled off, vernors should not consume any monoprop for stabilization. Also, they are a bit too powerful for stabilizing such a small craft, so they most likely "overshoot", tilting the ship too much, which mean that vernors on the opposite side have to counter that, again with inappropriate force...thus waste of fuel.