Brown University scientists say they have built a robotic bat wing that could lead to the development of a flapping aircraft. The 8-inch wing is based on the lesser dog-faced fruit bat. "A bird has three wing joints at the shoulder, elbow and wrist. Bats also have several joints within each of the fingers, providing up to 25 joints in the wing, all of which allow it to change the shape of the wing dramatically, for more maneuverability and fine control over flight," said researcher Joseph Bahlman.