The propellers of the world's ships and boats create a constant drone that disrupts ocean life. New propeller designs based on loops could one day quiet that drone and be more fuel efficient. Sharrow ...

Years after the space race, propeller design remained a sea-trial-and-error endeavor: haul, tweak the props, relaunch, sea-trial, repeat. Finally, the U.S. Navy paid ...

This paper by TSAW Drones discusses the need for less noise in UAVs, how these toroidals can benefit the drone industry, how these propellers came to be and how exactly they reduce the noise. Also, in ...