Tiny airplanes with insectlike flapping wings may soon explore difficult-to-reach places such as earthquake and urban war zones and sewage pipes. A U.K. team of aeronautical engineers from Cranfield University is working with zoologists from Cambridge University to build small, unmanned aircraft called micro air vehicles (MAV). The miniature planes will have a maximum wingspan of about 6 in. and will be able to lift off, hover, and fly.
"Contrary to popular opinion, insects do not just flap up and down," says Professor Clifford Friend, Cranfield University. "Their wings trace a figure-of-eight pattern as they beat, flipping the entire wing upside down on the upstroke to create maximum lift." Eventually researchers hope to mimic this with "smart" flapping wings powered by a central motor. But first on the agenda: developing reliable subsystems. Only limited work can take place on control, navigation, and payloads before a reliable platform capable of agile, low-speed flight is available.
"We are concentrating on flies because they are evolutionarily advanced. Nature has already done a lot of optimization," says Friend. Unlike conventional aircraft that have additional features such as ailerons on the wings for control, insect wings bend and flex in response to muscle control and to air pushing against them in flight. To be successful, MAVs must master this basic motion using elastic elements.
Researchers have built simple models and used computer simulations to investigate possible range of motion using racks and gears. Additionally, the project will look at unsteady and high lift aerodynamics in a framework similar to that used for helicopter rotor design.