It might also be mentioned that a thin bladed 3' diameter experimental free-wheeling device is pictured on the website that ran super fast with its flat, doubled, offset blades, implying that your four-bladers could be tried with two doubled-blades instead to gain reinforcement in each from one blade behind the other with a strut between.
Knucks the (Air) Knucklehead www.integener.com "Be sure and safe while making something that works well. This is a cause for much joy when done."
Knucks www.integener.com [ Parent ]