Originally Posted by Whiskers
I totally agree with the claim, "... airfolis are not really relevant at the reynolds numbers we as hobbyists are concerned with."
At the high end of contest flying, where 1000% effort is deemed worth 1% improvement, airfoil selection and construction may well come into play.
i should probably phrase it as "LESS relevant" instead. i.e. toilet paper rolls and pool noodles make crummy wings.
generally anything that promotes separation improves stall. as mentioned my friend had similar results with a row of tiny vortex generators (angled fins) across the top. the more the merrier. i got kf type stall resistance with a simple strip of triangle cross-section placed just in front of Cl. both resulted in considerably more drag than kf and also lacked its wing strength benefit.