Hi, in some cases it is hard to get the exact position of the leading edge of a NACA profile, because the t-parameter (curve parameter) is not at 0.5 anymore. That is why I wrote a small feature which finds the t-parameter for the point which has the longest distance to the trailing edge. Furthermore I included a few lines in the feature to measure the elapsed time. This can be helpful to optimize your feature. (Thanks Stefan for this.) regards Carsten FindNacaStart.fdb FindProfileLeadingEdge.fdf