I have built two "Transatlantic" slope soarers from 1990 RCM plans. One for myself and another for a friend. They both seem unstable and prone to stalling and poor penetration. I have had no luck finding anyone else with hands-on experience with these planes. They have full floating stabilators. My friend has used the top of the fuse as his zero reference and decided the wings had nearly 6 degrees of positive incidence and adjusted it down to about 1/2 degree positive. He is more pleased with the way it handles now but I am not convinced.

My questions are: What is the best reference to measure incidence on a floating stabilator equipped plane? If the top of the fuse does make the best reference, why would a designer want that much positive incidence?

Thanks for looking, Cliff