A couple teams have discovered an issue where rwdc.exe is not sorting airfoil coordinates correctly. If you see lines crossing the interior of your airfoil this could be a problem for you. The negative impact would be heavier sections. RWDC was designed to automatically sort points from the trailing edge to the leading edge, around the opposite side back to the trailing edge. The program automatically took care of both concave and convex features in the airfoil. RESOLUTION: Manually sort points (from TE to LE, and back on other side to TE) in your input. It does not matter whether the upper or lower surface is first in the list of points. Download and use the updated version of rwdc.exe (version 1.1). Mark Fischer will be posting the updated version shortly on the Getting Started page. Include a NOSORT parameter on your SECTION input. Input format: SECTION name NOSORT 1.0 0.0 ...