jmb52760, good links, thanks. I should spend some time with foilsim or similar before proceeding. It looks to me that both the Sikorsky S72 and the Boeing X50 are using oval shaped airfoils, and at least one, if not both are using Coanda effect. I don't think that is practical for a park flyer, but the shape is interesting and I want to learn more about that. The fact that the oval airfoil is used on a helicopter rotor blade suggest the C of P and pitch moments are quite different to normal foils, and may be close to my ideal.

Cheers from the Barfly.