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 such as: - Viscous (or inviscid) analysis of an existing airfoil - Airfoil design and redesign by interactive specification of a surface speed distribution via screen cursor or mouse - Airfoil redesign by interactive specification of new geometric parameters - Blending of airfoils - Drag polar calculation with fixed or varying Reynolds and/or Mach numbers. - Plotting of geometry, pressure distributions, and polars