Toroidal Propellers

[FWB]

Came across this. Very expensive though.

 

[Tranona]

The Sharrow has been around for many years and has not made much impression on the market, maybe because the theoretical benefits do not seem to translate into real benefits sufficient to justify its high price. Comes up regularly on the MOBO forum.

 

[Thistle]

105% efficiency strongly suggests snake oil.

 

[westernman]

These guys are very enthusiastic, but are quoting nothing like 105% improvement. More like ~30% efficiency improvement at slightly lower speed.