From John Fisher:
Here are the two rudder examples, 812 is the thicker one and 813 is thinner. The % thickness is the same on both, but 812 is thicker over more of the rudder since it was a 1/8" pc of balsa that was rounded on the ends. 813 was made by two pcs of 1/64 ply expanded over a 1/8" shaft.
They clearly show the difference in cross section, however they’re a little small to judge the details. Interested in contrasting the radius of the leading edge. Is there much of a difference between the two rudders in the first .125 to .25 of the foil? Typically sections with a sharp leading edge will lead to a pronounced stall as the flow can’t make the sharp turn to stay attached to the low pressure side.
