Jeff,

I'm not sure if your problem is the exact same as the one I had with a plane. I had a heck of a time trying to get it stay straight and track down the runway. I figured out it was a problem with the wheels. They would move as teh plane picked up speed and one would bind on the axle. I found this Dubro product to help keep the wheel in place and the problem went away.

It is Dubro product number 342, if the link doesn't work. http://www.shopatron.com/product/pro...d=DUB342/101.0

Hope this helps.