A (free) must have for the more technical rocketry enthused. XFOIL is an interactive program for the design and analysis of subsonic isolated airfoils. It consists of a collection of menu-driven routines which perform various useful functions http://raphael.mit.edu/xfoil/ Link from James Lanier, Chemroc -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics