Thick, high lift airfoils with wide speed range?

lr27 · Aug 3, 2023

I've been looking at airfoils. Imagine a 1-26 that's been on a diet and has magically lost 75 lbs. It has a d-tube wing now. Goal is have a very slow stall speed (i.e. high Cl) (or to use a smaller chord) with a reasonable speed range. Needs to be quite thick. 20 percent would be nice. The Reynolds number might run from 900k at the tip to 1,700k at the root. Or, at a Cl of 0.2, 1,,986k and 3,836. A Reynolds number would vary by 1/sqrt of Cl, of course, and getting down to 0.2 or 0.3 with relatively low drag would be nice. According to Xfoil, the original 43012A is almost matched by the 43018, as used (sort of) on the Sky Pup. Except the former is a little better under a Cl of 0.4. The Ara D, modified to have a sharp leading edge, is lower drag. Both have trailing edges that probably aren't too challenging, and both have relatively mild pitching moments. The Eppler 749 and NACA 63-820 have very similar performance. However, the two have more extensive laminar flow than the first two, which might mean they'd have to be more precisely made to give good performance. They have relatively large pitching moments, too. And the trailing edges would be harder to build.

I'm sort of looking at what would be possible with a self launching glider based somewhat on the Sky Pup. Part 103 legal. So, at least for now, flaps are out.

Anyone want to suggest other airfoils I should be looking at? Also, wind tunnel data at pertinent Reynolds numbers?