By Kristina Grifantini

(November 27, 2009) - A prototype solar-powered airplane completed several important tests last Thursday and Friday.

Solar Impulse's HB-SIA, which was finished this past summer, taxied down a runway using power from the 11,000 solar cells covering its wings and did a series of acceleration and braking tests. The next test will be revving up the plane to its 35km/hour take-off speed.

Founder of Solar Impulse, Bertrand Piccard, a former astronaut and the first man to circle the world nonstop in a balloon, hopes to perform the same feet in a solar-powered plane derived from on the HB-SIA design. Solar Impulse aims to test the prototype in flight next year and to achieve a 36-hour flight without fuel shortly after that. Results from these tests will be used to build a solar-powered plane to will attempt a transcontinental flight sometime after 2012.

A number of solar-powered aircraft exist already, such NASA's Helios, the Solar Riser glider or the Sunseeker which flew across the US in 1990 using a mix of solar power and gliding.

The Solar Impulse prototype is made of lightweight materials, weighing only 3,500 pounds and it has a wingspan of 210 feet. It is intended to fly at only 28 miles per hour to keep energy consumption low. It will store solar energy for night flight.

See the accompanying video that shows computer simulations of Solar Impulse's plane, and the real thing on the runway.