In a Leading Edge blog titled “Humpback Helos,” International Editor Robert Wall writes of the German DLR's quest to improve helo efficiency. DLR is flight-testing rotor mods inspired by humpback whales. Noting that bumps on the mammal's fins led to a much better flow inspired the development of Leading-Edge Vortex Generators (circled), each with a diameter of 6 mm and weight of 0.04 grams.
This is a great idea . . . [W]e are still a long way from properly understanding aerodynamics, so ideas like this one are well worth investigating.