Wash-In and Boundary Layer: In a letter to me, Jonathan Pitt points out, "The elevator [D-tube?] is oversized in order to reattach the boundary-layer at the hinge line. It is just another bit of aerodynamic tweaking that Irv Culver added to make a great flying sailplane. Another point to look at is the small wash-in built into the horizontal stabilizer. This wash-in helps to self-trim the stick forces as the airspeed increases ... but it can be a trouble spot when you attach the D-tube skin." If you carefully draw a nose-to-trailing-edge line on each airfoil and carefully analyze the amount of camber above and below this line ... you will clearly see a built-in twist to the H Stab.