Starship! such a beautiful plane!
I've been a fan since 2009 when I came to this site for help in a scratch build. I even met Bob Scherer, who keeps one of the last ones flying. It's based at Orange County, John Wayne Airport,CA. Here's a link to my 4 ft ws foam version.
It includes plans, pictures and some interesting links to Burt Rutan, Bob Scherer and others.
You're right about the rudders on my 92" version. What I was trying to do was to mimic the full size plane by having them move only in one direction - outwards on the inside wingtip The result was that they were fairly sloppy close to neutral, they didn't return precisely to that position. I didn't think it would cause a problem but, sure enough, something went wrong. My theory is that, the more aileron travel I transmitted, the more the wing would warp the wrong way.
I did get some successful turns, slow ones. On a fairly windy day, it was just not responding fast enough. :