Severe Pull during docking manuevers

[thiosk]

I've been having troubles with weirdness in my crafts that I'm attributing to SAS. I've noted a lot of severe rocking motion and inability to keep things stable. For instance, Cupola, large RCS, Medium grey tank. This guy was going bananas when I had the SAS on. I attributed it to the fuel decreasing and changing the center of mass.

I'm interested in ships designed for routine space station construction and maintenance, and am planning on doing lots of docking and undocking. As such I want a unit that can be detached, rotated, and positioned with ease, with highly balanced RCS and stable SAS.

Any tips would be appreciated! How can torque go wrong when balancing a vessel and what can I use to prevent it?

[Vanamonde]

It's hard to diagnose without pics, but as a first guess, it sounds like your RCS thrust is not centered (causing a swing to one side) and then the SAS imposes a correction (swinging to the other side), in which case, just about every tap of a translation key is going to trigger a oscillation.

[mhoram]

You might want to try this addon. It helps positioning the RCS thrusters.

http://forum.kerbalspaceprogram.com/threads/35996-0-22-RCS-Build-Aid-v0-4-For-balanced-placement-of-RCS-GUI-added

[breakthrough]

With fine control on, RCS ports will throttle their thrust based on how far they are offset from the center of mass. Combined with torque, the sway stays manageable as long as RCS ports are surrounding the center of mass.

Swept wings are very lightweight for how long they are, so I use them as arms for mounting RCS blocks on. Variations of this claw docker design have always translated without trouble for me.

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