Hummingbird UAV flies by flapping its wings

A tiny new unmanned air vehicle with flapping wings can hover, fly at high speed and negotiate indoor and outdoor environments while sending back video imagery, even though it weighs just nineteen grams. The Hummingbird Nano Air Vehicle (NAV) has been developed by AeroVironment Inc. of Monrovia, California, under a contract with the Pentagon's Defense Advanced Research Projects Agency (DARPA). In a recent demonstration the Hummingbird was shown flying outside, entering a building through an open doorway and reconnoitering the interior before coming out again. The craft can hover for eight minutes on internal batteries. It is highly efficient thanks to a biomimetic design which borrows some of the features found in small birds. At very small scales, the Reynolds number of a wing (the ratio of inertia to drag) is much lower than with manned aircraft. Under these circumstances flapping wings are more effective at providing lift than propellers or rotors. (Image: Aerovironment) The craft's avian appearance is enhanced by a body made to look like a hummingbird, though it has landing skids rather than feet and a tail. The handmade prototype has a wingspan of sixteen centimetres and can fly at up to 11 miles per hour. It can cope with a five mile an hour crosswind. DARPA's development plans for the NAV include indoor navigation without GPS, automated collision avoidance and improved power and communication systems.
One Per Cent: Hummingbird UAV flies by flapping its wings