A NACA series 4 aerofoil generator, based on the equations and methods set out in Abbot and von Doenhoff’s classic student aerodynamicists’ text, Theory of Wing Sections. Although the 4 series aerofoils are rather old (they were developed in the thirties) they are still useful for low-speed applications such as wind turbines or velomobile fairings. They are also tolerant of innacuracies in construction, dirt and insect accumulation, and real-world conditions generally.

I’ve improved on the methods desribed in the book by using Cosine spacing of the samples along the Thickness Distribution, working from Trailing Edge to Leading Edge so that there are more samples at the critical Leading Edge, as well as wrapping the Thickness Distribution around the Mean Line as a single curve from Trailing Edge to Trailing Edge. I’ve also used Fit Curve on the Mean Line to smooth out the bump that inevitably occurs with Abbot and von Doenhoff’s method, and the Flow component to map the Thickness Distribution onto the Mean Line: a lot less fuss than using the mathematical approach that was necessary in the 1930s!

NACA 4 series aerofoil generator - R6.gh (19.8 KB)