By Stuart F. Brown

(FORTUNE Magazine) – Monrovia, Calif. Founded 1971

The best engineers, it is said, are born with an optimizer gene that compels them to find ways to get the most from the least. That perfectly describes AeroVironment, a firm founded by renowned inventor Paul MacCready, 78, who proved that solar-powered flight was more than just a dream. AeroVironment's command of low-speed aerodynamics, ultralight materials and structures, and miserly energy consumption have helped it build a family of hand-launched drone aircraft. Its ten-pound backpackable Pointer enabled soldiers in Afghanistan and Iraq to see over hills through videocamera eyes. Its latest big project, SkyTower, aims to use unpiloted vehicles circling in the stratosphere--about 70,000 feet--to provide broadband telecom service to urban areas. --Stuart F. Brown