Falling with the Falcon

Peregrines think simple thoughts: See food. Fly down. Go fast. Very fast.

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Franklin describes Frightful’s configuration when going into “hyper drive” as asymmetric; she deforms her shoulders the way a person would when trying to squeeze through a very small opening. “She’s slipping through molecules,” he says; “the asymmetry seems to be part of that.” He holds no hope that airplanes could imitate the malleability and asymmetry of a diving falcon. But his years of study and observation of falcons all over the world lead him to suggest that copying certain aspects of peregrine flight could improve aircraft efficiency.

John Szabo, an articulate and agreeable theoretical mathematician in Cheney, Washington, is a master falconer who collaborates closely with the Franklins. Szabo has calculated that when the two-pound Frightful pulls out of a high-speed dive clutching her nearly two-pound lure, she undergoes 27 Gs of deceleration: At that moment, she and her prize weigh slightly more than 100 pounds. Based on Szabo’s mathematical modeling and Franklin’s measurements of Frightful in mid-dive, the two men think the secret to a falcon’s speed may be in the jagged edges of its feathers, which mitigate the effects of air turbulence and make the bird more streamlined. The jagged edges disrupt the airflow less than squared-off edges would. “Look at the wake turbulence behind a canoe compared to a rowboat with a square transom,” Szabo says.

Szabo, who has done research for NASA in computational fluid dynamics, says that nature is full of these kinds of adaptations for moving through air and water efficiently. In the case of shark skin, for instance, the ribbed texture of the scales helps to reduce drag, a finding that in recent years caught the interest of swimsuit manufacturers. “It wasn’t until the 2000 Olympics that the obvious advantage of minuscule dimples in swimsuits could radically improve efficiency over smooth suits by more effectively diffusing turbulence,” says Szabo. “Altering the design of swimsuits took a cross-disciplinary approach.”

Likewise, a stamped or incised surface that replicates the jaggedness of falcon feather tips, could, he and Franklin suspect, significantly improve an aircraft’s efficiency. “Look at how vortex generators have revolutionized aviation,” Franklin says. “There’s still room for improvement in drag reduction.”

Although they arrived at this conclusion independently from aeronautical engineers, the falconers are hardly alone in suggesting it. Nearly 20 years ago, scientists at 3M developed an adhesive film with a micro-structured texture that, when applied to the surfaces of an aircraft wing, will reduce drag, resulting in greater fuel efficiency. Even a one percent reduction in fuel use for a wide-body jet saves about $100,000 in fuel for each aircraft annually, according to 3M’s Web site.

Not everyone agrees that Franklin’s research tells us much about the behavior of wild peregrines. Some falcon experts have called his studies artificial, because freefalling from 17,000 feet is unnatural behavior for falcons, who normally stay below 14,000 feet. Franklin says the only reason he goes so high is to get more time for his observations, and that doing so doesn’t make much difference to the bird. “Falcons can accelerate from 100 mph to 200-plus mph in eight seconds in pursuit of prey,” he says. “They don’t need that vertical space to accelerate. But they often ride thermals up to cloud base, getting a free ride up the column of air, checking out everything in the airspace for a meal. They soar at altitude, practically invisible, waiting for prey—then they stoop. To say that stooping from 14,000-plus feet is not normal for a falcon is like observing a Ferrari on a crowded freeway doing 55 mph and assuming that’s all they can do.”

Ken and Suzanne Franklin would love to see their falcon studies contribute to even modest improvements in aircraft efficiency. And even though aerospace companies are hardly beating their door down, Franklin takes every opportunity to deliver his message. Last September, he addressed a meeting for Boeing engineers and the British Royal Society of Aeronautical Engineers at the Museum of Flight in Seattle, and he regularly talks to groups of pilots and birders.

In the meantime, he and Frightful continue their high-dive act. Looking each other in the eye while falling at 242 mph, they share a knowledge and a bond that few people, let alone people and animals, could ever know.

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