Advances in technology often occur by accident, when you were looking for or developing something else. Such was the case with a new propeller design that sought to reduce the annoying noise traditional propeller driven fixed wing or helicopter aircraft use. A suitable new propeller design was created that looked odd (it had a twisted-toroid ring shape) but was indeed much quieter, producing a whisper rather than the whiny roar common with conventional propellers. Then it was found that the toroid propeller was also more effective at propulsion. The new propeller was tested in the water and also found to produce more propulsive power as well as being quieter. This is an enormously big deal for submarine propellers as reducing their underwater sound is a survival issue. The toroidal design seemed to have the same impact at sea as in the air. This new design is important for surface ships as well. The quieter operation makes it more difficult for submarines or some torpedo homing systems to detect the ship,
A lot more testing of the new propeller shape is required to discover how reliable and continuously effective it is, and under what conditions or mediums such as air and water. This may require a redesign of most helicopters to use a quad-copter design common in small UAVs (Unmanned aerial vehicles) and a few new manned designs. There will be a lot of other changes, some of them not yet perceived. The new prop design was possible because of faster and more flexible simulation software as well as 3-D printers to quickly create prototypes for testing.