The Nano Air Vehicle (NAV) is a small bird-sized aircraft that uses flapping wings to fly and hover. It was developed by UAV-pioneers Aeronvironment with funding from (you guessed it) the Pentagon's Defense Advanced Projects Research Agency (DARPA). Aeronvionment is now working to improve the robot so it can fly in outside winds. From New Scientist:
Aeronvironment's flapper appears to achieve propulsion, stabilisation and control all at once using its paired wings. Details of the technology are confidential, however, under the US ITAR arms control export restrictions..."Hover no bother for flapping 'nano' aircraft"
DARPA has said it wants a 10-gram aircraft with a 7.5-centimetre wingspanMovie Camera that can explore caves and other hiding places, relaying GPS data and images to base. It will need to fly at 10 metres per second and withstand 2.5-metre-per-second gusts of wind.
That goal is a long way off, but DARPA programme manager Todd Hylton says Aeronvironment is on the right track. "Progress to date puts us on the path to such a vehicle," he says.