Imagine an unmanned aerial vehicle (UAV) that could fly for days rather than hours, aiding soldiers on reconnaissance missions or supplying emergency communications to disaster-affected regions. AeroVironment, which built the first human- and solar-powered airplanes, has successfully flown a prototype of a UAV that will be able to remain at high altitudes for longer than a week at a time. Unlike earlier solar-powered systems, which had to power the vehicle and store enough electricity for nighttime flying, Global Observer uses fuel-cell-powered electric motors to drive eight propellers.

1977/1979

1, 2: Gossamer Condor/Albatross

Paul MacCready becomes the "father of human-powered flight" when his 70-pound Gossamer Condor completes the first sustained, controlled human-powered flight. Two years later, his team flies the Gossamer Albatross, which has a 96-foot wingspan and is built mostly of plastic and carbon fiber, across the English Channel. That flight, made by cyclist Bryan Allen, takes a stately three hours to accomplish, though it covers only 23 miles.



1981

3: Solar Challenger

JULY 1922

World War I flying ace and frequent Popular Science contributor Eddie Rickenbacker
envisioned a monstrous airliner that would fly in "but a very few years." With a boat-like fuselage that let it alight on land and water, Rickenbacker's concept looks slightly like the Boeing Model 314 Clipper, the flying boat that made the first scheduled trans-Atlantic flight in 1939. The Clipper's 74 seats converted into 40 bunks—but there was no observation deck. The 300-foot wingspan of the giant would have dwarfed the Clipper's 152 feet.

In August 1901, the Wright brothers were ready to give up. They had spent a frustrating summer testing their latest glider on the beach at Kitty Hawk, North Carolina, and nothing seemed to go as planned. The glider, a biplane with a 22-foot wingspan, was difficult to control and almost killed Wilbur. It proved even less maneuverable than the glider the Wrights had built and flown the previous year. Wilbur, nursing bruises from his crash in the dunes, was especially depressed.