Looking to Nature

Two Air Force Office of Scientific Research-sponsored university projects into how bats and insects flap their wings to maneuver in tight spots, yet remain stable in adverse weather, may yield valuable insights that improve the performance of micro air vehicles. “Birds, bats, and insects have some highly varied mechanical properties that we really have not incorporated in engineering,” said Wei Shyy, an aerospace engineering professor from the University of Michigan, who leads one of these studies. He added, “They’re not only lighter, but they also have more adaptive structures.” Shyy’s group is focusing on learning how and why flexible wing structures affect lift and thrust generation, especially in unsteady environments. Insights could improve the hovering and forward flight modes of MAVs by delaying stall, enhancing stability, and increasing thrust, he said. Kenny Breuer, a fluid mechanics professor from Brown University, leads the second project. His team’s work includes capturing video footage of bats flying in a wind tunnel and measuring the fluid velocities in their wakes. His team is also collecting data on flight properties of bats in different environments and among different species of bats. His researchers are developing computational methods for simulating complex, moving, flexible structures; mapping the neurophysiology of bat sensor and motor systems; and creating control systems that could be applied to future MAVs. (AFOSR report by Molly Lachance)