Quote Originally Posted by Jonathan View Post
You beat me to it, nice explanation! I used the same method with vectors in my wind turbine blade profile and tool-path calculation program. Using the equation for a NACCA airfoil, which doesn't simplify as nicely.
Cheers! Sounds lke a nice project, hope you differentiated the eq to get the tangents ;-) Somewhere I still have the source I wrote for a surface model with 310 bicubic patches. That a patch bounded by four cubic splines (48 coeficcients) (just in case!), all continuous with each other. I had algorithms to calculate the normals at any point (for shading), integrals for area, routines that solved the intersections of them with planes for crossections. And, believe it or not, it ran on a BBC model B because the IBM pc hadn't been invented yet! I remember rewriting it in pascal for the pc.
Tom