Rethinking aircraft design by imitating nature’s best-kept secrets could help solve a variety of aviation challenges. Biomimicry—or biologically inspired engineering—is providing engineers with invaluable insight on how to design lighter and more fuel-efficient aircraft.
When Daedalus and his son Icarus from classic Greek mythology found themselves imprisoned by King Minos of Crete, they began to wonder: what if they could escape by flying away like birds?
According to the legend, Daedalus crafted bird-like wings made of feathers and wax, which enabled them to fly out of their prison. But Icarus failed to heed his father’s warning and flew too close to the sun. The wax melted and Icarus fell to his death. Daedalus heeded the warning and flew to the island of Sicily. His wing design—inspired by birds—had flown him to safety.
Like Daedalus, aeronautical engineers have been inspired by birds for decades. In fact, the study and imitation of nature’s best-kept secrets to help solve human challenges has a name: biomimicry. As the aviation industry faces the colossal challenge of how to make aviation more sustainable, nature is increasingly proving to have some invaluable insight—from the flight secrets of birds to the movement of sharks—on how to make aircraft lighter and more fuel efficient.
As the aviation industry faces the colossal challenge of how to make aviation more sustainable, nature is increasingly proving to have some invaluable insight on how to make aircraft lighter, faster and more fuel efficient.
Ever noticed how snow geese often fly in a “V shape”? This is because follower geese expend less energy by surfing on the wakes (i.e. left-over kinetic energy of moving air in the sky) created by the leader bird. When flying in this way, geese immediately benefit from free lift, which enables them to stay aloft with minimal fatigue over long distances.
The Airbus fello’fly demonstrator project aims to prove the viability of this flight technique—known as “wake-energy retrieval”—for commercial aircraft. Every in-flight aircraft creates a wake, so positioning a follower aircraft in the air upwash of the leader could help the follower to reap the benefits of this “free” lift. In fact, according to preliminary studies conducted by the Airbus fello’fly team, this collaborative activity could produce fuel savings of between 5-10% per fello’fly trip.
Of all the birds of prey, the bald eagle reigns supreme. This large, powerfully built bird has long, broad wings that contribute to faster flight. Eagles, like albatrosses, are soaring birds—this means they can provide engineers with a lot of insight into dealing with wind gusts, and more.
Airbus’ “Bird of Prey” conceptual airliner is inspired by the eagle. The theoretical design is a hybrid-electric, turbo-propeller aircraft for regional air transportation, which mimics the eagle’s wing and tail structure, and features individually controlled feathers that provide active flight control.
Although Bird of Prey is not intended to represent an actual aircraft, it does provide insight into what a future regional aircraft could look like based on technologies that currently form the basis of Airbus research. This includes hybrid-electric propulsion, active control systems and advanced composite structures.
The long-eared owl is one of nature’s most silent hunters, thanks to a wing design that enables it to fly in almost complete silence. When most birds fly, turbulence—created when air flows over the surface of their wings—causes noise. However, the long-eared owl is one of only a few birds that has primary feathers serrated like a comb. This breaks down turbulence into smaller currents called micro-turbulences. The serrated feathers thus are able to muffle the sound of air flowing over the wing by enabling the air to pass easily through.
Today’s aircraft already produce 75% less noise than those produced 40 years ago. Airbus engineers are studying owls to further unlock the secrets of silent flight. Some ideas include a retractable, brush-like fringe to mimic the owl’s serrated feathers on wings and a velvety coating on aircraft landing gear.
Like birds, sharks can also teach engineers a lot about aircraft movement. A shark’s tail is its propeller: it moves forward by swinging its tail back and forth, which pushes water around its fins. Aircraft move forward in the same way, pushing air around their wings to create lift. The shark also has dorsal fins that work exactly like the vertical stabiliser wing on an aircraft, giving it exceptional manoeuvrability.
In 2013, Airbus introduced “sharklets”—or vertical wing-tip extensions that resemble a shark’s dorsal fin—as a retrofit to its A320 Family aircraft. These aerodynamic surfaces, which are mounted vertically at the wingtips, significantly reduce the size of the wingtip vortex, thus reducing induced drag. Today, all members of the A320neo Family are fitted with sharklets as a standard.