Hey, I can stay on-topic here.
An helical vertical axis tri-plane wing.
https://static.turbosquid.com/Previe...8ddaLarger.jpg
The airfoils would be timber bamboo, split in thirds, lashed together and twisted when they're green, then the airfoil shaped and carbonized when they are dried. The culms would attach to the shaft via three struts.
20ft of hex bar to act as a torsion bar that stores energy to spin up from stopped.