Solar Impulse

As the Solar Impulse heads off for its latest feat — its first intercontinental flight — here's a closer look at the aircraft that's making some large strides in the green aircraft race.

Solar Impulse
Solar Impulse
Since the Solar Impulse project was first launched in 2003, it has achieved some pretty noteworthy feats, including maintaining continuous flight for more than 26 hours. (Photo by Solar Impulse | Jean Revillard)
Solar Impulse
Solar Impulse
On Thursday, pilot André Borschberg took off for the Solar Impulse's latest journey — its first intercontinental flight. (Photo by Solar Impulse | Jean Revillard)
Solar Impulse
Solar Impulse
Several design aspects of the Solar Impulse work together to produce the optimal combination of performance and efficiency. (Photo by Solar Impulse | Jean Revillard)
Solar Impulse
Solar Impulse
The Solar Impulse's high-aspect ratio wing spans more than 200 feet and equals the length of an Airbus A340 wing. (Photo by Solar Impulse | Fred Merz)
Solar Impulse
Solar Impulse
The Solar Impulse is covered with close to 12,000 monocrystalline silicon solar cells, most of which are located on the wing. While the efficiency of the cells is great, the engineering team had to make compromises in order to ensure an overall aircraft weight that could perform both in daytime and nighttime conditions. (Photo by Solar Impulse | Stéphane Gros)
Solar Impulse
Solar Impulse
The solar energy harvested by the cells powers the aircraft's four brushless, sensorless electric motors. (Photo by Solar Impulse | Jean Revillard)
Solar Impulse
Solar Impulse
The four pods beneath the wing each contain one of the motors, as well as a polymer lithium battery with 70 accumulators. The substantial weight of the batteries — together they make up 1/4 of the aircraft's entire weight — necessitated a light-weight airframe. (Photo by Solar Impulse | Jean Revillard)
Solar Impulse
Solar Impulse
That airframe is constructed of carbon fiber, with 20 carbon fiber ribs located between the upper and lower wing surface. (Photo by Solar Impulse | Fred Merz)
Solar Impulse
Solar Impulse
The twin-blade propellers are confined to 400 revolutions per minute. (Photo by Solar Impulse | Stéphane Gros)
Solar Impulse
Solar Impulse
The aircraft can lift off at just a little over 20 mph and averages a speed just below 45 mph. (Photo by Solar Impulse | Fred Merz)
Solar Impulse
Solar Impulse
Work has already started on a second Solar Impulse prototype slated to travel around the world in 2014. (Photo by Solar Impulse | Jean Revillard)
Solar Impulse
Solar Impulse
For the around the world flight, the new prototype will come equipped with a more spacious cockpit and better avionics than the original aircraft. (Photo by Solar Impulse | Jean Revillard)
Solar Impulse
Solar Impulse
It will also have an increased payload, as well as better protection for flight into wet weather. (Photo by Solar Impulse | Fred Merz)
Solar Impulse
Solar Impulse
The Solar Impulse on the ground at Brussels Airport in 2011. (Photo by Solar Impulse | Fred Merz)
Solar Impulse
Solar Impulse
The Solar Impulse during its night flight over Switzerland in 2010. (Photo by Solar Impulse | Pool | Keystone | Dominique Favre)
Solar Impulse
Solar Impulse
The Solar Impulse on approach in Switzerland earlier this year. (Photo by Solar Impulse | Jean Revillard)
Solar Impulse
Solar Impulse
The Solar Impulse on the ground at Brussels airport. (Photo by Solar Impulse | Jean Revillard)