The Defense Advanced Research Projects Agency (DARPA) kicked off its Nano Air Vehicle (NAV) program in 2005, with the goal of developing agile flying systems that could fit in one hand.
This recently released video chronicles the development of a "hummingbird" flyer by Aerovironment from concept to prototype and its eventual public debut.
According to DARPA, a number of difficult design and engineering challenges were overcome in the course of the program, particularly in the wing structure, propulsion and control actuators.
As such, numerous prototypes were built and tested to assess and improve system performance.
The final prototype managed to achieve the milestone of 2-wing flapping hovering and fast forward flight - with all controls and power sources implemented via modulation of the wing strokes in a shape resembling a real hummingbird.
The nano hummingbird flyer is also equipped with an on-board camera which relays real-time video to the pilot.