http://www.nytimes.com/2010/07/09/world/europe/09plane.html?hp

Slender as a stick insect, a solar-powered experimental airplane
with a huge wing span completed its first test flight of more than 24 hours on
Thursday, powered overnight by energy collected from the sun during a day aloft
over Switzerland.

The organizers said the flight was the longest and highest by a solar-powered
craft, reaching an altitude of just over 28,000 feet above sea level, at an
average speed of 23 knots, around 25 miles per hour.