Aerodynamics pose limits on helicopters particularly in movement, where it meets more resistance and can cause an imbalance affecting the controllability of the aircraft. Now researchers at the German Aerospace Center in Göttingen, have discovered and flight-tested a way to increase manoeuvrability using an idea they got from observing humpback whales.
The main advantage of a helicopter is its ability to take-off and land vertically via their main rotor, said researchers. But this creates aerodynamic disadvantages during a fast forward flight or manoeuvring, because of turbulence and the loss of lift that exerts large forces on the rotor.
"This limits the top speed of helicopters at high altitude and, in particular, their manoeuvrability," said Kai Richter in a press release
from the DLR Institute, but researchers at Göttingen discovered a solution courtesy of humpback whales, in particular their large pectoral fins.
"These marine mammals are renowned for their great speed and acrobatic skills," says Holger Mai from the DLR Institute of Aeroelasticity, despite weighing up to 30 tons and reaching lengths of up to 50 feet. Humpback whales maneuver extremely well in their surroundings and can reach speeds of 16.5 miles per hour in the ocean.
The whales' secret weapon said the Institute, is it large pectoral fins containing characteristic bumps along the front edge. Mai said, "research has shown that these bumps cause stalling to occur significantly later underwater and increase buoyancy."
The bumps, patented artificially as Leading-Edge Vortex Generators (LEVoGs), were applied to helicopter rotors in the hope they would delay the onset of stalling, and so far tests have been promising. Pilots, Richter said, after experiments conducted in a wind tunnel with 186 rubber LEVoGs glued to each of the helicopter’s four rotor blades, "have already noticed a difference in the behaviour of the rotor blades."
"Flow phenomena in water are similar to those in air; they just need to be scaled accordingly," says Mai. The artificial bumps on helicopters are smaller than those on the whale and have a diameter of six millimeters, and a weight of just 0.04 grams.
The bumps on the pectoral fins of humpbacks have been used as inspiration before, in the development of turbine blades used in wind turbines, hydroelectric turbines and ventilation fans that increase efficiency.
Other marine animals have also contributed to technology over the years. The ability of a shark's skin for example that can reduce drag as it swims along, was used in the development of swimwear worn by by US swimmer, Michael Phelps at the Beijing Olympics.
DLR researchers meanwhile, said that existing helicopters could be retrofitted with LEVoGs at very little expense, making them safer and more manageable.
Scientists have often tapped biomimicry to improve technology. Provided research is humane, and animals are studied in their natural habitats with minimal invasion, who knows what secrets they will reveal, given the chance?