Airfiol design is a big factor. L/E radius and trailing edge thickness would be were i would find less drag.. You can use, water, as a easy and fairly accuate method to test drag. Glass or sand paper will let you see what is related to, surface drag only. By running water down an incline, with test material ,on the incline you can see it live!! Turbulance is the real problem. "Trailing edge is a killer".. Drag it through water,behind a canoe..or build a test rig,run water over it and read drag ..Then ,after all that work,you can tell us ,for free, what you foud out!!!! lol [X(]