A solar-powered plane that has shattered three world records plans to go the distance again this year. The pilots of the "Solar Impulse" want to fly more than 1,500 miles (2,500 kilometers) without a drop of fuel during a two-day journey — a dress rehearsal for the ultimate goal of flying around the world in 2014.
Two Swiss pilots, Bertrand Piccard and Andre Borschberg, plan to switch off on flying the solar-powered plane at a technical stopover in Spain during the upcoming flight scheduled for May or June. That would allow them to tag-team the 48-hour flight over the Pyrenees Mountains (the natural border between France and Spain) and the Mediterranean Sea so that they can safely land in Morocco.
The Solar Impulse team has already put seven years of work into their aircraft design with the wingspan of an Airbus A340 jetliner, the weight of a family car and the engine power of a scooter. Solar Impulse's four propellers draw an average of 8 horsepower — about what the Wright Brothers had available when they first flew in 1903. Each of the four engine pods also have lithium polymer batteries.
Solar cells cover the upper wing to harness the power of sunlight in flight. The aircraft also has a strong, lightweight structure based on carbon fiber-honeycomb composites.
That design helped Solar Impulse set a new flight-time record as a manned plane powered only by sunlight during a day-long voyage in 2010. It also set endurance and altitude records during the flight that lasted 26 hours, 10 minutes and 19 seconds.
Such solar-powered aeronautic feats do more than just impress — they also raise new possibilities for commercial planes that could rely on electricity rather than jet fuel. Electric motors could be far more efficient than today's jet engines, but electric planes remain limited by the weight of heavy batteries needed to store electricity.
Still, Solar Impulse has proved that the right combination of renewable energy and lightweight materials could theoretically keep a plane airborne almost indefinitely.