Propeller design is sort of a black art. Activity factor, aspect ratio, etc.
Curious, does anyone know how an airfoil cross section would work with this as opposed to flat blades? I would think there would be efficiencies to be had with the right symmetrical airfoil.
Flat plate l/d is very predictable, but also not so efficient.
An airfoil could theoretically be employed that has less drag (and therefor less noise) and higher lift when alpha changes - implying greater output per energy expended. Also, an airfoil could be employed to get either more output, or less required motor force from the driver. (speaker coil) A fatter airfoil near the base, and less towards the tip would maximize and even out the the velocity cone across the disc.
Lot's of low rent stuff stacked up into a medium rent pile.