The Karman-Trefftz airfoils are a set of profiles created from conformally mapping a circle into an airfoil by manipulating the Epsilon, Kappa, and Tau parameters. While not exactly correct in definition, you can think of Epsilon as controlling the thickness and leading edge curvature, Kappa as controlling the camber, and Tau as the angle at the trailing edge. These airfoils are of particular interest in aerodynamics because not only is the circle itself conformally mapped to the airfoil, but the analytic solution of the flow field about a circle (remember sources and sinks?) may also be conformally mapped as well which provides analytic flow solutions to each airfoil shape.
The CST (Class-Shape Transformation) airfoils or Kulfan airfoils are a family of airfoil shapes that are defined by a parameterization of the upper and lower curves. In most cases, users will likely begin with a desired airfoil shape and then use the “Fit CST” feature of chosen degree to approximate that shape. From there, the individual parameters of the upper and lower surface curves may be modified to achieve the desired profile.
The Biconvex airfoil (or opposed-arc airfoil) is a sharp-edged supersonic airfoil defined by the thickness to chord ratio. Note that these airfoils are typically very thin, having relatively low thickness to chord ratios.
The NACA 16-Series airfoils are automatically generated according to the ideal lift coefficient and the thickness to chord ratio from the functions that define the shape. This series is a subset of the NACA 1-Series airfoils with the location of minimum pressure 60% along the chord. The airfoil name will also be automatically updated with the parameters according to convention.
The NACA 4- and 5-Series Mod airfoils provide additional control over the leading edge radius index and the location of maximum thickness. The naming convention follows the usual method for 4- and 5-series airfoils with the extension of two additional digits indicating these new values. The leading edge radius index ranges from 0.0 (sharp) to 9.0 (semicircular) with a default of 6.0 corresponding to the traditional series.
