A Quieter Propeller: Chasing the Unicorn

This may be old news, but let’s look at the toroidal propeller patent from 2020. It is a valiant attempt to make drones more palatable for the general public.

The idea came from the “ring wing” design, an airplane with a wing in the shape of a ring. Tests in WW2 were promising, because this design spreads out the vortices normally concentrated at the tips of regular wings.

The inventor of this design (interview here: https://youtu.be/E8L8I0dLh_o?si=9OKId5uP7x_wgXuT) thought ‘well, propellers are just wings spinning around, why not have them as ring wings?’ Hence, the toroidal propeller was born.

“Public acceptance of multirotor drones is critical to their widespread use; acoustically quieter propeller designs that are able to serve as drop-in replacements for conventional propellers may, more than any other technological advancement, accelerate the acceptance and wide use of drones in public spaces.”

Evolution in the field of propellers is slower than in other fields. The results of this toroidal propeller have been mixed, as witnessed in several YouTube videos.

Claim 1: “Toroidal propeller comprising: a hub supporting a plurality of elongate propeller elements in which a tip of a leading propeller element curves into contact with a trailing propeller element to form a closed structure with increased stiffness and reduced acoustic signature.”

This is a very nice, elegant claim, and it will take someone very creative to go around it.

Title: “Toroidal propeller”

US Patent No: 10836466

Filed (US Reg): 2017-11-06

Granted: 2020-11-17

Applicant: Massachusetts Institute of Technology