AeroVironment, the California-based company behind the largest, highest and longest flying unmanned aircraft system (UAS), the Global Observer, has now achieved a remarkable technical milestone with a much smaller aircraft. With its "Nano Hummingbird" the company has for the first time achieved controlled precision hovering and fast-forward flight of a two-wing, flapping wing aircraft that carries its own energy source and relies only on its flapping wings for propulsion and control.

The hand-made final concept demonstrator Nano Hummingbird has a wingspan of 16 cm (6.5 in) and weighs just 19 g (2/3 oz), which is less than the weight of a AA battery. Into this tiny and lightweight package the AeroVironment UAS team has managed to cram all the systems required for flight, including batteries, motors, communications systems and even a video camera.

The aircraft can climb and descend vertically, fly sideways left and right, fly forward and backward, as well as rotating clockwise and counter-clockwise - all under remote control and while carrying a video camera payload. It is even capable of doing a 360-degree loop.

The Nano Hummingbird doing a 360 degree loop

The Nano Hummingbird can be fitted with a removable body fairing, which is shaped to have the appearance of a real hummingbird and, although it is larger and heavier than an average hummingbird, the aircraft is actually smaller and lighter than the largest hummingbird found in nature.

The achievement was part of the Phase II contract awarded by DARPA to AeroVironment to design and build a flying prototype "hummingbird-like" aircraft for the Nano Air Vehicle (NAV) program.

To meet the technical goals of the contract AeroVironment needed to:

Demonstrate precision hover flight within a virtual two-meter diameter sphere for one minute.

Demonstrate hover stability in a wind gust flight which required the aircraft to hover and tolerate a two-meter per second (five mph) wind gust from the side, without drifting downwind more than one meter.

Demonstrate a continuous hover endurance of eight minutes with no external power source.

Fly and demonstrate controlled, transition flight from hover to 11 mph (17.7 km/h) fast forward flight and back to hover flight.

Demonstrate flying from outdoors to indoors, and back outdoors through a normal-size doorway.

Demonstrate flying indoors 'heads-down' where the pilot operates the aircraft only looking at the live video image stream from the aircraft, without looking at or hearing the aircraft directly.

Fly the aircraft in hover and fast forward flight with bird-shaped body and bird-shaped wings.

AeroVironment says that not only did its Nano Hummingbird meet all of these requirements, but that it also exceeded many of them.

Check out the two videos below to see the Nano Humminbird in action. The first video from 2009 shows the Nano Hummingbird at an early stage of development, while the second video shows a flight of the final concept demonstrator.

AeroVironment flapping-wing nano-UAV