doctor jason wrote:
smaller the better
Yes, I agree that one easily may get such a conclusion at first sight.
But according to statements found in some books, the Re applied to a wing chord is not the same as the Re inside the boundary layer itself.
When the airflow meets the wing, a stagnation point occurs at the leading edge (LE) where Re is zero. There the flow is divided to pass above and below the wing.
As the boundary layer flow moves along the wings surface, the Re varies and at every point is proportional to the distance measured around the airfoil between the actual point and the LE.
Thus the Re in the boundary layer increases as the distance from LE increases.
Since the boundary layer flow has to travel longer way from LE to TE with a thicker airfoil, the thicker will have higher Re inside its boundary layer than the thinner one assuming the same airspeed.
Cheers,