Archimedes Windmill with airfoil design and generator

thingiverse

## Update: Second Design 1. A bug in sweep() was fixed, and the problem of blade termination was solved by introducing a wedge-shaped design. The hidden airfoil design is demonstrated in cross-sectional view. 2. An airfoil-shaped 50 magnet ring was added to harvest electric energy. Stator coils will be attached to a bracket (not shown yet) after magnet delivery and first print. 3. Intended practical uses include wind lights, chargers, sailing boat position lights. Why not also harness some river current with it? ## Background and First Design Studying logarithmic spirals, I stumbled upon the Archimedes windmill patented and produced by a Rotterdam company called *The Archimedes*. Because I liked the idea behind it, I started to implement a first version to see it running, then a second version much closer to the original because I also liked the design itself. Obviously, the company's windmill has blades made from metal sheets rolled around an axis with no specific aerodynamic design. Although they claim an amazingly high efficiency for such a small wind turbine as well as a silent run, I suspected that a proper airfoil design might not be wrong - and also enhance harmony and statics of the design. So, I started to implement a library for NACA airfoil data and a sweeper to seemlessly juggle around airfoils with changing parameters in 3D space on arbitrary trajectories. This thing is the outcome for now. I guess I will also add some terminal profile, but I haven't spent time on finding a good solution for this. I added an STL file for direct printing. There, I added a foot to stabilize the print. It is meant to be cut off after print to enhance aerodynamics. As shaft, I use a 2mm bike spoke. I drill up the hole in the turbine (1.9-2mm drill bit) and heat the spoke before poking it in. The holes in the bracket I drilled up with 2.5mm. The bracket easily opens up 10mm to plug the turbine in.