Thomas, Slow, J.Cran
great explanations.
I fully agree with you cran when you say it's a defeating engeneering
a kind of "driving the worse"..
I still having questions in the choice of a OA213 and a VR7 or NACA0012 , the first has, appearently a design made for higher AOA , similar to the VR4.
My questions would be what choice for thinner chords (lets say 16 cm). and what are the wayto reduce the reverse flow and gain efficiency.
I'm also wondering in the sanded surface on the upper surface... it sould be very slick... the sanded should be under, to slow the flow.. or is it a way to deal with a non-laminar but averaged up flow ?
Thanks to all, this really helps.