 The airfoil was switched to the NACA 66,2-(1.8)15.5 a=.6 at the root and the NACA 66,2-(1.8)12 a=.6 at the tip.These airfoils were designed to give less drag than the previous NAA/NACA 45-100.In addition, the planform was a simple trapezoid, with no leading edge extension at the root.