I am glad to see a thread on airfoils, I have been in this hobby for 60 years, starting with Baby ROG for you younger guys that was a rubber powered Rise off the Ground, I progressed through C/L freeeflight, single channel etc, my problem is this, I instruct and fly everything from 3 channel Senorita's up to my 103 inch C130 and lots in between, they all fly great , most of the trainers with a Clark Y my Herk uses NACA 23012, I have triied to undersatnd Reynolds numbers, Epler and many others but it seems that in modeling the foil is not that important as long as the wing loading is light and you got lots of power, for example, we had a guy flying his 33% Edge 3D tons of power, the airfoil is fully symetrical and VERY thisk, great show but then there was the guy with his 36 " foamy P51, a chunk of foam for a wing and he put on the same show CONFUSED LOL Mike