For years, engineers have been working on making smaller and smaller UAVs (unmanned aerial vehicles). DARPA (Defense Research Advanced Projects Agency) has been taking the lead for years, and is now pushing the envelope by providing a second round of funding for the development of nano-UAVs, unmanned flyers with a mass of just 10 grams, approximately equivalent to two nickels. The company designing the flyer, AeroVironment, recently announced reaching a never-before-achieved technical milestone: a 10-gram nano-UAV that can engage in controlled hovering flight by flapping its two wings, using only an on-board power source and its wings for propulsion and control.
Previous nano-UAVs of similar size used a tether system for power and/or control. What makes the nano-UAV even more attention-grabbing than prior UAVs is biomimicry — it looks like a hummingbird, and the company’s press release comes with a concept image of a nano-UAV that is painted just like a hummingbird. AeroVironment tested 90 different wing designs before settling on the hummingbird design. Like a pencil balanced on its tip (or a human walking), the design is inherently unstable. It constantly wants to tumble out of control, and is only corrected by an automatic control system. The aircraft has a wingspan of about five inches, about five times larger than the smallest UAV ever built, but the extra size is essential for the UAV to withstand wind gusts of 2.5 m (8.2 ft) per second, one of the requirements of DARPA’s Nano Air Vehicle program.