Decoupler not...decoupling

[GJames]

So I have a Moho probe lander in Kerbin orbit and I wanted to ditch the previous stage before I zoomed off into interplanetary space. However, when I fired the decoupler and the seperatrons, the stage didn't separate and my whole craft got put onto a sub-orbital trajectory...

Are there any bugs with decouplers, or am I doing something wrong? I have got struts linking the two stages together to minimise any wobbling but I thought that they usually disappear, don't they?

Its the TR-18A Stack Decoupler and the only mods I am using are Kerbal Alarm Clock, Engineer and the fairings from KW Rocketry...

Thanks in advance.

EDIT: Definitely not the struts, I checked with a de-strutted version on the launchpad and it still won't separate...

Edited June 9, 2013 by GJames

[Bashkire]

can you post a picture(s) / .craft file of your vessel so we can diagnose the problem better?

As a preliminary, I would say make sure that you don't have anything in the way or clipping with the offending stage, make sure that the decoupler is the right way round, and if you have Quantum Struts (no idea if it's included in any of the mods you've said above, I roll with MechJeb only myself) make sure they're off before hand.

Hope this helps!

[GJames]

The offending decoupler is the one below the nuclear engine...

[Johnno]

Have you tried separating it manually? Alternatively move it into its own staging sequence and stage without firing the sepratrons. Can quicksave beforehand and try a few different things. Otherwise you may have to redo it in VAB, or check your persistance file to see if you can figure out how it's connected.

Have never had any issues myself with them, apart from putting them in the wrong staging sequence and separating stuff I shouldn't have or other way around. I don't see any other decouplers on your ship, but check your staging anyway.

[GJames]

Checked staging, all seems good. Manually separating it makes it play the decoupling sound and a puff of smoke comes from the decoupler like normal, but nothing else happens. I'm editing the persistence file now, I'll report back in a bit.

EDIT: I could force the decoupler to decouple by editing the persistence file, but I couldnt get rid of the struts, so I was a bit stuck. I figured out that I had built the Moho Lander starting with an old launcher save that was from 0.19, so that could be where something went wrong...

I ended up giving up and just changing it to a seperator in the VAB before relaunching it.

Thanks for the help though!

Edited June 9, 2013 by GJames

[Klajan]

Most likely cause is that a part is clipped into the decoupler. Sometimes twisting your craft around will brake it loose, or you can put sepratrons on the stage twist tem sligtly to the side, so the sperated stage seperates itsself spinning. This works always for me.

Edit: Well since you already did all I suggested... I am out of ideas...

[nhnifong]

This happens when you connects decouplers with the alt f12 menu's part clipping option turned on, even if the decoupler looks like it is connected normally.

Temporarily turning it off when you connect decouples has completely fixed the issue for me.

[GJames]

This happens when you connects decouplers with the alt f12 menu's part clipping option turned on, even if the decoupler looks like it is connected normally.

Temporarily turning it off when you connect decouples has completely fixed the issue for me.

Ahhh, thanks for that, I might not have so many wasted launches now!