Airplanes of the Future Could Be Fitted with Feather-Like Flaps

These findings could be hugely important for the future of the aviation industry. Climate change is making weather conditions more unpredictable and severe. Over the past four decades, the frequency of extreme turbulence events has increased by 55 percent. To ensure passenger safety, aircraft must become more resilient and capable of performing agile maneuvers in challenging conditions without compromising aircraft stability and passenger safety.

At the same time, air traffic volume is continuing to increase, making it crucial to explore innovations that enhance aircraft efficiency and can help decarbonize flying without having to rely solely on innovations in fuel. Passive advancements could not only help with this, but would do so without depending on complex electronic systems.

Yet the path to getting such technology adopted commercially is challenging—and this has been the case for a lot of other animal-inspired technologies. For instance, in the 1980s, scientists discovered that sharks have small protrusions, called riblets, covering their bodies, which reduce drag as they glide through water. They wondered if applying a similar design to aircraft could significantly cut fuel consumption. In 1997, researchers quantified that the shark-skin-style riblets can reduce drag on airplanes by nearly 10 percent. However, commercial testing on real aircraft didn’t begin until 2016.

Lufthansa Technik, a German aerospace company, eventually developed AeroSHARK, an aircraft surface technology inspired by shark skin. “Today, 25 aircraft across seven airlines have been modified with our sharkskin technology, and the number is steadily growing,” says Lea Klinge, spokesperson at Lufthansa Technik. She adds that such innovations require decades of research, and that integrating new solutions into existing fleets without disrupting operations remains a major challenge.

When considering how to scale these feather-inspired flaps, “there are some logistical challenges in terms of what kind of materials we can make those flaps out of or how we can properly attach them to the wings,” Wissa says. And rolling out such an innovation would not be as simple as adding the plastic film to the small prototype aircraft in the team’s experiment. “Oftentimes, integrating innovative solutions at a commercial level can quickly become complex and multidisciplinary,” says Ruxandra Botez, an aerospace engineer at the university ETS Montreal. An aircraft has to go through a variety of safety tests and certifications, which can easily take several years. Botez also notes that most modern aircraft are built with incremental improvements on previous models, with manufacturers reluctant to stray far from existing designs.

Lentink, however, argues that focusing solely on commercial scalability is the wrong approach. He adds that if innovations with clear scalability are the only ones to be tested, researchers won’t think outside the box. “If you truly want to innovate in aerospace, then you do have to come up with these completely wild ideas,” he says. Staying too close to the final application limits engineers’ ability to create new things. He believes that the covert-feather-inspired flaps, in their current guise, probably aren’t close to immediate application. “But I don’t see it as criticism,” he says. “I see it as researchers developing critical ideas that can now be developed further in this technological pipeline towards an application.”

The scientists WIRED spoke to stress that the future of aircraft design must continue drawing inspiration from nature. Birds are more agile, capable, and maneuverable than anything humans have built. “If we want to create aircraft that can fly as efficiently and adaptably in unpredictable conditions, we’ll inevitably need to incorporate aspects of bird flight into next-generation designs,” says Sedky.

Even if they don’t make it onto large commercial planes, Wissa says these feather-inspired innovations could be game-changing for small aircraft, which are expected to play a major role in the future of aviation, such as in package delivery or urban air mobility—there are multiple startups trying to develop flying taxi services, for example. Such aircraft will likely need to take off and land in tight spaces. These innovations could boost lift and control during such high-angle maneuvers.

“As aircraft get smaller, they also become more susceptible to environmental factors like gusts, high winds, and turbulent airflows,” Wissa explains. Equipped with these flaps, small flying vehicles of the future might be able to handle “gusts that would have thrown an aircraft out of the sky.”