Is the Toroidal Propeller the Greatest Prop Advance since the Wright Brothers?

These interestingly-shaped toroidal propellers may be a significant advance for both the aviation and marine sectors. An MIT student team found itself wondering whether prop noise in multirotors could be mitigated with differently-shaped propellers, and this extraordinary design was developed. Much quieter than traditional propellers in air and water, they also demonstrate large efficiency gains. A key issue with flying multicopters is annoying rotor noise, often described as "whiny”. Drone applications in towns and cities...