On a bright, sunny afternoon on July 9, a white unmanned air vehicle (UAV), its two 2.75-horsepower engines buzzing, taxied smoothly down a finely mowed field of dark green grass. After a short distance, it lifted off and effortlessly soared to an altitude of about 325 feet. It banked right, then began flying large, lazy circles above the rolling, grassy hills of the Wiltshire Downs in southern England.
After 10 minutes, the drone, which has a wingspan of around 13 feet, gently returned to Earth and taxied back to its ground crew. It was the second of 20 short test flights it made that day. For the first 14, the drone was controlled remotely by a pilot on the ground. The last six tests were on autopilot run from a laptop.