A helicopter's rotor design may allow for vertical takeoffs but that comes at a price -- the backwards moving blade counteracts the helicopter's forward momentum, causing it to stall at high speeds. But one German firm believes that outfitting the blades with bumps inspired by the fins of humpback whales.
A humpback whale swims at roughly five times the speed of Michael Phelps, over 16 MPH. This is due in part to the bumps found along the front of the animal's pectoral fins. At one point in every stroke, the whale's movement "stalls" when there isn't enough lift to keep it from sinking. The bumps on the fins cause this stalling point to occur later in the stroke, providing an aerodynamic advantage.
This is the same principal at work in the quarter-inch-wide rotor blade bumps currently being tested by the DLR Institute of Aerodynamics and Flow Technology in Germany -- they provide an aerodynamic advantage by increasing the maximum speed a chopper can travel without stalling. The technology has been patented already and dubbed "Leading-Edge Vortex Generators."
Researchers have just completed wind tunnel testing with 186 of these bumps affixed to the leading edges of a helicopter rotor. "The pilots have already noticed a difference in the behaviour of the rotor blades," said Kai Richter from the DLR Institute, "The next step is a flight using special measuring equipment to accurately record the effects."
Once the bumps have been scaled accordingly to provide the optimum amount of lift the technology should become available to all helicopters. Older models can have the bumps installed and new chopper rotors will be built with them. [MSNBC]
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