Dang, RW, I wish we could go flying with you. We're watching a storm front that is supposed to dump 6-10 inches of wet white on us by Saturday night. Maybe it will be good enough to go fly indoor RC by Sunday, but CL is shot for the weekend.

Yeah, I'd put the stock muffler on for the first flights. Better a little nose heavy, for sure. When you get comfortable with it, swap to the lighter muffler and see how it is with the CG back. If it's too touchy, you can try narrowing the line spacing at the handle. We need to find the flight trimming chart for you. I'll hunt up a link.

Some rules of thumb for CG's are: about 15% of the mean chord for flapless planes, about 20% for the Twister. Designs with flaps and long tail moments go back as far as 30%. The long tail makes them stable enough to be flyable.

I would also set the leadout guide so the centerpoint between the leadouts is about 1/4 to 1/2 inch behind the CG. This compensates for the sag in the flying lines. You know how the lines are never straight, but hang back from the drag? The idea is to end up with plane flying tangent to the circle, neither yawed in or out. The yaw creates tons of drag and hurts line tension. That's why no one uses much rudder offset anymore, like all the old plans showed. It just causes yaw and drag problems. I set all my rudders dead ahead and use only the tiniest bit of engine offset. That's pretty standard practice.

Well, got to start getting ready for work tonight. Catch you later.
Kelvin