Why does my spaceplane keep rolling out of control?

[Alex319]

I am trying to build a spaceplane that uses two jet engines to get up to high altitude and then uses a rocket to get into orbit. It seems stable in the pitch direction, a little less stable in the yaw direction, but it is almost impossible to control in the roll direction. It always seems to roll one way or another out of control after a couple minutes of flight.

One thing I have noticed is that the roll controls on this work weirdly. If I try to roll it right, say, it will roll right a little bit but then zoom back left, even beyond where it was initially. I have tried looking at some spaceplane tutorials but they always seem to address stability in the pitch direction, and I haven't been able to find one that addresses stability in the roll direction. What are the possible causes of this problem?

(I am trying to copy and paste the picture in here but it doesn't seem to work; it always gives the error "The text you have entered is too long.")

[Guest Darth Gerbil]

If the image is on steam, open your steam screenshot page and copy the url of the image into the thread.

[eddiew]

If you're by any chance trying to carry an M700 scanner in that plane, remove it... I've been having all sorts of wacky issues when I cram one into a cargo bay :S

And you can't just paste pictures into a forum; you need to host them somewhere on the internet. Imgur is popular