Space station ocsillation

[Okie Rocket]

I've been playing for a few months and I've built space stations before with out too much trouble. In the last couple days though, I put a fuel station in orbit of the Mun. I do have some mods, one of them is Kethane, and some other parts that looked handy. On one of my trips from a Mun kethane deposit to the station I got the Mun station most of the way full with fuel and kethane. But in the middle of transferring the tanks on the station started wobbling and within 5 seconds or so the station broke up. It happened several times and seems to happen when the tanks opposite each other are at about the same level. If they're significantly uneven it doesn't happen, at least not yet. The weirder thing is, I already did this same thing once before with no trouble. I got a Kethane processing station at Minmus filled to capacity with no problems but now even if it twitches when it's full it disintegrates, too.

I couldn't find any other reports similar. Don't know if it's a physics bug or a mod. It's only just started and all I did before was add some different engines.

[Kerba Fett]

If SAS was on, the station may have torn itself apart as the ship SAS fights with the station SAS. It starts as an oscillation that gets wors and worse till something breaks.

It's a good idea to turn off SAS just before the docking ports touch. (at that point you shouldn't need it)

[capi3101]

Do you have SAS on when you're doing this? I've heard of folks having problems with fuel transfers and SAS before; this sounds like that particular bug.

EDIT: Ninja'd.

[TechnicalK3rbal]

If you can't get it to stop, quicksave and then quickload it. That should put all the parts back into the original positions.

[Okie Rocket]

Even with SAS off it can still happen. The Minmus station is really easy to get going even though it never did it until now. A little wiggle in the wrong direction gets it dancing and then nothing I do can save it, even time warping only delays the destruction. Once it started right after loading physics when I jumped from another ship, never even touched the controls. I could quicksave and load but this is something that's designed to make interplanetary trips if necessary so I'd rather not have to do that all the way to Jool and then do I always do, hit F5 when I meant F9.

[RocketPilot573]

Quick question, are there any cubic octagonal struts on this craft?

[Rassa Farlander]

Ive had problems with this before. Im not if its sas related but it seems to happen, with me at least, when transferring fuel or in unbalanced stations, it seems to start as the center of mass starts to shift. Also, Ive had it happen with stations that have big long solar arrays as well. I usually quickload, but that doesnt always work. Ive had to de-orbit and re-design stations with this problem before.

[Okie Rocket]

No cubic or octagonal struts, so it's not that. I did some experimenting with the persistence file, changing resource level and such. The odds of trouble go way up if the drive section is empty but the storage tanks are full or close to it. The storage tanks are two of the orange tanks and two large kethane tanks. They're attached to a scaled up version of the stock six way hub. It seems like when the center of mass is in that area it gets extra squirrely, even though that's where I want it. If one tank is half full and the others are topped off, everything seems ok. Of course, it'll never fly straight like that.

[TechnicalK3rbal]

You should try the kerbal joint reinforcement mod. It makes structural joints stronger and thus less wiggly.

[Tery215]

Blame the Kraken.

You could try using Quantum Struts (or KAS struts(or any other docking strut(or regular struts))) to keep your crafts not exploding from wobble.

[iBeej]

This is almost always SAS related. Make sure SAS is disabled for every module docking to the station.

I have a space station comprised of 2,000 parts, which is 12 seperate docking modules, and one time I fat fingered SAS and I watched it go in to an oscillation that tore itself in to pieces. (Including my frame rate).

SAS is bad for space stations m'kay.

[Okie Rocket]

Blame the Kraken.

Yeah, there are a couple other instances that make me wonder if the Kraken is completely dead. Like a lander with no engine accelerating to escape velocity.

I had Kerbal joint reinforcement installed. At first, I wondered if it was acting funny so I removed it but no dice. Still funky. The quantum struts seem to help, though. Trying them out, I turn them off and get the station shaking. They can settle it down again as long as I don't wait too long to turn them back on.

Still, this probably calls for redesign.

[radonek]

I've encountered similar problem after docking small lander to station radialy. Turning off SAS did not help. After some trying, I hit gold: from close observation it seemded source of the oscilation is in the lander. In a moment of inspiration, I clicked "control from here" on main space station and oscillation vanished.

My guess is that it has to do with controling part being far from COM of whole craft. Or maybe just off-axis. Since pumping stuff around change COM, I guess you are riding the same Kraken.

[m4rt14n]

Ive had to scrap my mothership because of this. Well that and the lag. God... the lag....

[700NitroXpress]

You should post a picture so everyone can see the ship. Sometimes it's parts on the ship that are the problem and not SAS or mods.

[Okie Rocket]

This is the Minmus station. It actually fell apart right after taking the screenshot. I launched another one with the quantum struts that seems stable but I'd love it if they weren't necessary.

[Okie Rocket]

https://www.dropbox.com/s/n7yldwb13u58tct/screenshot5.png

https://www.dropbox.com/s/xcihxrgbwo4m3yj/screenshot3.png

[Kerba Fett]

Large parts normally have larger attach nodes. doesn't that affect the strength of the attachment? When you rescaled the 6 way hub did you do anything with the attach nodes?

The game may still be seeing it as a small part with weak connections and that may be where the wobble is coming from.

[700NitroXpress]

Make one without the mod part in the middle and use all stock and see if it still falls apart.

[Okie Rocket]

I used to use the stock hub and some adapters for stations. It worked ok but I didn't like how flexible it was and since my computer isn't as good as it once was the I've been trying to trim part counts. I got this down to 35.

I'm not the one that did the rescale. I found it on space port. I know how to tweak some config values but I basically know nothing about the attachment rules.

http://kerbalspaceprogram.com/large-hub/

Edited February 15, 2014 by Okie Rocket
added link and fixed some grammar

[700NitroXpress]

You could use one like this, minus the docking clamps it's 43 parts, all you have to do is add your kethane module where the lander can is. You really don't need that many engines on it.

[Mokmo]

The Joint Reinforcement mod did miracles for me. Saw the wobble start and subside where the station would've blown up already...

[Okie Rocket]

You really don't need that many engines on it.

I know I would get more delta-v with just one but I like having a little extra thrust and once it's fueled it's got enough delta-v anyway that I don't mind the loss.