In its continued quest to improve the efficiency of helicopters, the German aerospace center, DLR, is now flight testing rotor modifications inspired by Humpback whales.
Researchers noticed that bumps on the mammal’s fins have led to much better flow. The observation has inspired the development, patenting, and now testing of so-called Leading-Edge Vortex Generators, each with a diameter of 6 mm and weight of 0.04 g.
DLR believes the devices could delay the onset of dynamic stall, with the resulting increase in drag. With the devices, it sees the opportunity for helos to fly faster and with reduced vibration.
The vortex generators have undergone wind-tunnel tests and now the first flight trial on a DLR-owned Bo 105 in Braunschweig, Germany. DLR says it glued 186 of the vortex generators to each of the four blades.
"The pilots have already noticed a difference in the behaviour of the rotor blades," Kai Richter from the DLR Institute of Aerodynamics and Flow Technology in Goettingen says in a statement announcing the findings. After having first examined safety issues, Richter says "the next step is a flight using special measuring equipment to accurately record the effects."
DLR sees potential for a low-cost retrofit of existing rotorcraft to improve performance. It adds that “for new helicopters, contours could be milled into the front edges of existing titanium blade designs during the manufacturing process.”