"The maneuverability of a bat in flight makes even Harry Potter’s quidditch performance look downright clumsy. While many people may be content to simply watch these aerial acrobats in wonder, Kenneth Breuer and Sharon Swartz are determined to understand the detailed aerodynamics of bat flight – and ultimately the evolutionary path that created it.
Breuer, a professor of engineering at Brown University, who studied mechanical aerodynamics earlier in his career, is particularly intrigued by bats because “they can generate different wing shapes and motions that other creatures can’t.”
“Bats have unique capabilities,” says Breuer, “but the goal is not to build something that looks like a bat. We want to understand bat flight and be able to incorporate some of the features of bat flight into an engineered vehicle.”
Swartz, an associate professor in ecology and evolutionary biology at Brown University, and longtime collaborator with Breuer, is particularly interested in how bats evolved their capabilities. “The assumption has always been that bats evolved from some sort of flying squirrel-type animals,” says Swartz. “Gliding has evolved in mammals seven times. That tells us that it’s really easy for an animal with skin to evolve into a glider, but going from a square gliding wing to a long, skinny flapping wing has not happened seven times. It might have happened once. And now it doesn’t look like bats have any relationship to these gliding things.”
Bat wings are highly articulated, with more than two dozen independent joints and a thin flexible membrane covering them. The videos, shot from four angles simultaneously and then synchronized, show how the complex movements of each wing stroke relate to overall flight speed, body position and angle of attack. Reflective markers placed on joints, along bones and at key points on the wing membrane allowed the researchers to accurately track the position and shape of bones throughout the wing stroke. (...)"