Posted by bcs616 on
URL: https://forum.librecad.org/spline-through-points-with-end-blended-tangentially-onto-a-circle-tp5720652.html

I want to represent a 2D section of a wing aerofoil shape.  The upper surface is defined as a set of data points, with a circular radius defined near the wing leading edge, and a flat surface for over the rear part of the wing.  I have used Spline through Points to produce a very credible looking smooth line through the data points.  By defining a complete circle at the leading edge, plus one additional point in the spline near the leading edge, I can set Snap to Entity and move the additional point onto the circle.  By moving the point with the mouse, the point slides around the circle, and I can set it by eye so that the spline looks to blend tangentially to the circle. Very pleasing. My question is please, can I get Librecad to determine the blend point automatically and so get the spline truly tangential to the circle?  Same question also for the rear part of the spline, where it is mean to blend with the falt surface, i.e. straight line.