The unique mechanical properties of bat wings could lead to a new breed of nature-inspired drone. A prototype built by researchers at the University of Southampton shows membrane wings can have improved aerodynamic properties and fly over longer distances on less power."The unique aspect of a bat wing is that it's made of muscles and, when it starts to flap the wing, the wing can actually deform and change shape. And the change in shape could make it more efficient and fly better," said professor Bharath Ganapathisubramani of Southampton's Aerodynamics and Flight Mechanics Group, which oversaw the project.Using a paper-thin rubber membrane, the team designed wings that mimic the physiology of the muscles in a bat's wing, changing shape in response to the forces it experiences.Robert Bleischwitz, who led the project, said the wing's structure created a series of vortices as air passed over it, giving it added lift.He said a membrane wing could stop a vehicle from falling, keeping it afloat because the dynamics in the surface trigger vortices that roll down the wing and these vortices produce lift."So you can use this vortex-generation to produce lift," Bleischwitz said.He said membrane wings in future would incorporate electro-active polymers that made them stiffen or relax, depending on an applied voltage, further increasing their performance. This replicates the control bats have over their wings during flight.Research conducted in 2014 by scientists at Brown University showed that bats have a tiny network of muscles in the skin of their wings that enables them to control the stiffness and curvature of their wings when they fly...