The Solar Impulse prototype (SIA) had it’s first extended flight test on Wednesday, April 7. It remained aloft for 87 minutes and reached an altitude of 1,200 meters (3,937 ft.).
Powered exclusively by solar energy, the carbon fiber framed SIA uses lithium polymer batteries to store electricity generated by massive solar panels on the upper wing and tail surfaces. Four, ten horsepower electric motors provide thrust and give the craft a cruising speed of 43 miles per hour. The wingspan of the prototype is 208 feet, roughly the same width as an Airbus A340.
A second airplane (the SIB) is planned for an attempt at global circumnavigation. The SIB will feature a pressurized cabin and supplemental oxygen for the pilot, allowing a cruising altitude of 39,000 feet. The wingspan of the SIB will be some 260 feet, making the SIB the widest aircraft in the world upon completion.