Why does this rocket ALWAYS pull upwards? both in space and in atmosphere.

[TomDRV]

As title

 

 

Also, I'm having probelms with the nose 'dancing' around and triggering a flip, is the an aerodynamic effect? I'm trying to make the rockets shorter to counter this but I'm having no luck.

[Corona688]

Your topic says 'pull up', your post says 'dances', which is right?

Your rocket is long enough that when your rockets gimbal, it causes the rocket to bend in the middle a little bit.  The engine isn't quite pointing where the control pod thinks it is, causing it to overreact, correct, and overreact on the way back, back and forth.

You could try turning off gimbaling in some of your rockets on the way up.  You could also put a control pod in the middle of the rocket, right-click it, and 'control from here', which wouldn't stop the flexing, but would stop it from going bananas when it happens.

Edited July 12, 2016 by Corona688

[bewing]

You may be experiencing this bug: http://bugs.kerbalspaceprogram.com/issues/10079

Thrusting or struts seem to cause the stacks of some rockets to bend in a particular direction. Which means that the thrust is then off-center. Which causes a slewing force. Unfortunately, the only answer I have is to keep redesigning the rocket until the issue goes away or becomes manageable enough.

The annoying thing is that struts can actually cause this problem, when they are the things you want to use to fix it.

Edited July 12, 2016 by bewing

[Ultimate Steve]

Try pressing ALT+X. It will reset your trim. If that doesn't work, I can't help you.

[JPLRepo]

Like the others said. Your COT and COM are misaligned.

[Red Iron Crown]

Both screenshots are showing a small amount of control input with SAS off, either trim needs to be reset (Alt-X) or MechJeb is trying to steer.