It's been amazing to watch how computer technologies have revolutionized the R/C aircraft world. The combination of high-efficiency brushless electric motors (first developed for DVD drives), lithium-ion batteries (developed for laptops) and spread-spectrum digital radio (popularized with WiFi) have created a class of small, quiet electric planes that are every bit their old noisy gas-powered predecessors. AMA membership is down even as R/C flying is booming because you don't need to go to a AMA certified field or join a AMA club to fly anymore. Today's planes are quiet and safe enough to fly in most parks.
More and more military UAVs are using this same technology, most notably the Raven, which is the most common UAV found in Afghanistan. (it uses a brushless electric and LiPo combination similar to that you can buy from any hobby store.)
Now, inevitably, the same revolution is coming to full-size planes. At Oshkosh, Sonex unveiled a prototype electric one-seater. From a Green Car Congress post:
"Since 1994 and Flash Flight’s feasibility study, the popularity of radio-controlled (RC) electric powered toy vehicles, gas-electric hybrid cars, and the boom in wireless electronic devices such as cell phones and PDA’s have pushed the state-of-the-art in battery, electric motor and controller technology.
Brushless DC cobalt motors are now lighter and more efficient. Advances in microprocessors have allowed motor controllers to be smaller, lighter and more efficient. Lithium Ion and Lithium Polymer battery technology has pushed the endurance, efficiency and power output of electronic devices, while shrinking in physical size and weight. The Sonex R&D team concluded that the time for this endeavor had arrived.
E-Flight’s proof-of-concept prototype will use the flight-proven Waiex airframe, flown single-pilot only, so that the emphasis can be placed solely on powerplant research and development. Initial top speeds will reach approximately 130 mph, and endurance is expected to range between 25-45 minutes or longer, depending upon power usage on each individual flight."