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Air Force-funded researchers from several universities are studying the flexible, flapping wings routinely used by bats and insects and mimicking their biological attributes to improve agility, speed and adaptability in MAV systems.
The Air Force Office of Scientific Research manages two projects on biologically-inspired flight, both part of the 2007 Multidisciplinary University Research Initiative (MURI), which provides funding for topics that rely on expertise in multiple disciplines.
Dr. Kenny Breuer, a fluid mechanics professor from Brown University, and Dr. Wei Shyy, an aerospace engineering professor from the University of Michigan, each lead a MURI project. Though their respective teams focus on different biological and engineering aspects of this problem, they share the same overall goal of understanding bat flight and its potential applications to MAVs.
“Future MAVs will need to be agile, robust and maneuverable, and our research will provide some guidance as to how we might incorporate these features using inspiration from biology,” says Breuer.
If successfully transitioned, this research could lead to small remote controlled aircraft that have the ability to move in complex environments such as forests, interiors of buildings, caves or tunnels.
“Birds, bats and insects have some highly varied mechanical properties that we really have not incorporated in engineering,” explains Shyy. “They’re not only lighter, but they also have more adaptive structures. These natural flyers have outstanding capabilities to remain airborne through wind gusts, rain and snow.”
Facing many of the same challenges posed by this complex, biological system, Dr. Breuer is working on a variety of efforts to unlock the mystery. One such effort involves capturing video footage of bats flying in a wind tunnel and measuring the fluid velocities in their wakes. Another involves studying flight properties in different environments and among different species of bats.
The results of these experiments and others have allowed Dr. Breuer to construct engineering models that mimic specific features found in bat flight.
His MURI partners from Oregon State University, Massachusetts Institute of Technology and the University of Maryland are also doing innovative research. They are developing computational methods for simulating complex, moving, flexible structures; mapping the neurophysiology of bat sensor and motor systems; and creating control systems that might be of use in MAV technologies.
Dr. Shyy’s team, comprised of faculty and students from the University of Michigan as well as colleagues from the Universities of Florida and Maryland, is focusing on hovering and forward flight modes of MAVs.
“Birds, bats and insects can fly in turbulent environments with fast, unpredictable wind gusts; yet, they can react almost instantaneously and adapt with their flexible wings,” says Shyy.
Knowing this, his team has placed particular emphasis on learning how and why flexible wing structures affect lift and thrust generation, especially in unsteady environments.
“If handled appropriately, flexible wing structures can delay stall, enhance stability and increase thrust,” Shyy adds.
This research should be very beneficial to the Air Force as it addresses two of the eight Focused Long Term Challenges (FLTCs) identified by the Air Force Research Laboratory. These FLTCs form a forward-looking science and technology plan that is vital to the organization’s ability to fulfill its mission.
Molly LaChance
The Pentagon Brief 