Hi, I am trying to approximate the length of a spline. I have circular cross section extruded perpendicular to the spline though the whole length.

My 3d cad software will not give me the spline length. I have used the volume / area of extruded circle is approximately equal to spline length. Of course this is really the cylinder formula to find the height of a cylinder.

Does anyone have an approximation ratio that I could multiply to reduce the cylinder volume formula to get the spline length closer? My one test shows 98%.

I don't have any way of analyzing the spline in terms of aspect ratio or curliness. Does anyone know of a way?

Thanks Cozmo