If there is a holy grail for the military it is probably a remote controlled flying spy the size of an insect or small bird. The problem up until today has been that when you get down to that size these flying robots have not been able to carry their own batteries and have had to be guided by wires that let them move in a limited fashion.
This may have changed if the reports about the smallest free-flying aircraft that is able to hover and climb with flapping wings is true. The nano air vehicle as it is being called was developed by Aeronvironment of Monrovia, California and the success to date has prompted the Pentagon to extend the program that began in 2007 with additional funding. The Pentagon is looking for a more rugged version that is capable of coping with wind and other outdoor flying hazards.
Aeronvironment has released video that shows its “nano air vehicle” (NAV), which is the size of a small bird or large insect, hovering indoors without such crutches and under radio control. “It is capable of climbing and descending vertically, flying sideways left and right, as well as forward and backward, under remote control,” says the company.
Source: New Scientist :: Hover no bother for flapping ‘nano’ aircraft