Spinning rockets

[Conannet]

What is the best way to center the mass of the rocket, so it doesnt spin uncontrollably. I'm making quite tall rockets and i tried some things but nothing helped. At first i tried to put the center of mass as close to the engines as possible, but no effect. I've also tried to put it as higher as possible, LOTS of RCS and SAS, but still it spins out of control as soon as i start my gravity turn, no matter how slow i make it.

[NecroBones]

I guess the first question I have is, what do you mean by "Spin"?

If it's spinning around the roll axis (spinning like a top), there are ways to deal with that by making sure struts are well placed, maybe adding fins, etc.

If you mean it's turning, or flipping end over end, you probably have a drag problem, or center of mass problem. It would be useful to see a screenshot with all of the "centers" displayed.

The center of thrust vector should point through the center of mass, but the center of mass can be either in front of, or behind it. The center of drag must be BEHIND the center of mass, or else your rocket simply won't fly straight. You'll get away with it early in the flight, before trying to turn, but as soon as you try to steer, it will lose control. This is the most likely scenario based on your description. If you're seeing this, you probably have wings or fins ahead of the center of mass. You'll need to take those off, or add bigger fins behind the center of mass.

Also keep in mind that your center of mass moves as fuel is consumed. Usually the CoM moves backward, as the fuel is drained from the upper-most tanks in the stage first. This can result in something being stable at first, but if the CoM and CoD are close together, it can become unstable as you consume fuel.

Have a screenshot?

[Mitchz95]

You want the command module and reaction wheels as close to the COM as possible. That should balance it.

It's kind of hard to do that with really tall rockets; I'd recommend building out rather than building up.

[Thomas988]

To see your rocket's center of mass while building, go down by the symmetry button on the bottom left and there should be a smaller button slightly to the left that has a little weight on it. Click on it, and a yellow and black sphere will show up right where the center of mass is. As for your spinning problem, make sure your center of thrust is inline with the center of mass. To see the center of thrust, find the button below the center of mass button. Clicking on it will toggle a purple and black sphere, appearing where the center of thrust is. Now, this is where you'll have to eyeball it and see if the arrow is inline with the center of mass. If to the side noticeably, your rocket will flip out.

I would show pictures, but I'm at school right now and the wifi here doesn't allow imgur. Sorry about that. Hopefully someone else will come along and help as well.

[Conannet]

I got all the centers right and it worked just fine! Thank you all Who would've thought that couple of wings could save a whole space program O_o

[Vanamonde]

This question about playing the game has been moved to Gameplay Questions.