Researchers design a new breed of unmanned aerial vehicle (UAV) using membrane wings inspired by bats, which they say has improved aerodynamics and can fly for longer. Matthew Stock reports.
Bat wings are a triumph of natural design. A flexible skin membrane gives them unique aerodynamic properties. This drone wants to copy that. By mimicking the bat's physiology its makers hope to present a new paradigm for drone design. Researchers built wings that change shape in response to the forces experienced during flight. In wind tunnel tests, the membrane shape was changed under varying wind conditions to optimise aerodynamic performance. (SOUNDBITE) (English) PROFESSOR BHARATH GANAPATHISUBRAMANI, UNIVERSITY OF SOUTHAMPTON, SAYING: "The membrane actually acts very much like a sail of a ship - when the flow hits it, it sort of changes shape and it gives you some aerodynamic performance. And not only does it change, it also starts to vibrate and fluctuate. And that fluctuation improves the aerodynamic performance even more." The wing's flexibility creates a whirling vortex of air as it passes over, providing extra lift. (SOUNDBITE) (English) ROBERT BLEISCHWITZ, PHD STUDENT AND DRONE DESIGNER, SAYING: "A membrane wing can keep it afloat because the dynamics in the surface trigger vortices which roll down the wing, and these vortices produce lift. So you can use this vortex generation to produce lift. And you need the membrane to excite, generate these vortices." While it can fly just above the surface of the ground, the developers say it's more efficient and stable over water. Two electric rotors produce a cushion of air under the wings, helping it to lift like a hovercraft. Once airborne, the rotors keep it on course. The team now wants to incorporate their membrane wings into typical unmanned aerial vehicles, paving the way for a new breed of bio-inspired drones.