The sight of birds soaring through the sky has inspired humans for generations before the invention of powered flight in the early 20th century. Still looking to learn from winged animals, a team of researchers from Princeton University is exploring how feather-like flaps on aircraft wings could improve stability and maneuverability. While there are still hurdles in scaling up the feature to airliners, the group’s findings so far were published in a paper last October.
Numerous bird species feature small covert feathers layered on their wings. As the name implies, these feathers remain hidden flat against the wing during normal flight but flare to mitigate turbulence during abrupt maneuvers like landings and sharp turns. The research focused on adapting this biomechanical feature for planes. The researchers trialed passive covert flaps atop the wing of a radio-controlled plane. The plastic flap ran the entire wing width and used tape as a hinge, far different from the traditional flaps planes use for takeoff and landing. They quickly discovered that the aerodynamic benefits were additive and fitted multiple rows of flaps. Wired reported:
“When Wissa and her team tested the flaps in a wind tunnel and on the prototype airplane, they found that the added flaps enhanced lift by up to 45 percent, reduced drag by nearly 31 percent, and helped prevent the sudden loss of lift that causes stalling, compared to when the aircraft was without the flaps.”
Aviation’s ever-evolving future
With the rise of extreme turbulence, it’s likely that feather-like flaps would be most effective for small aircraft. These planes are far more likely to crash than commercial airliners. There were 271 fatal crashes last year, based on National Transportation Safety Board data. From a twin-engine Navajo splitting in half after slamming into several cars at a Texas intersection to a single-engine Piper crashing into a dragstrip RV lot, crashes happen for various reasons. Everything that could mitigate dangerous situations would be more than welcome.
These flaps aren’t the first time nature inspired a feature on modern planes. Lufthansa Technik, the engineering arm of the similarly-named German flag carrier, developed sharkskin technology for large airplanes. The riblet-textured film, called Aeroshark, acts like dimples on a golf ball and optimizes airflow over a plane to reduce drag and improve fuel efficiency.
The future of aviation is ever-evolving, with manufacturers looking for ways to make planes more fuel-efficient and more profitable to operate. Open-fan engines could be the next big innovation for large airliners. Airbus tested CFM International’s open-fan concept on its massive A380 a few years ago. The companies hope that engines without cowlings can reduce carbon emissions by 20 percent through just improved fuel efficiency.
