ROUGH CUT (NO REPORTER NARRATION)<br/> <br />The solar-powered plane called Solar Impulse landed at Washington Dulles International Airport on Sunday (June 16) completing the fourth and second-to-last leg of it's cross-country flight powered only by the sun.<br/> <br />Solar Impulse took off from St. Louis and after a 14-hour stopover in Cincinnati landed in Dulles at 12:15 a.m.EDT (0415gmt)<br/> <br />The brainchild of Swiss pilots Bertrand Piccard and André Borschberg, Solar Impulse flies at an average pace of just 43 miles per hour (69 km per hour). Both co-founders take turns flying the plane, which has a single-seat cockpit. It began its cross-country sojourn on May 3 with an 18-hour-plus flight from northern California to Phoenix.<br/> <br />With the wingspan of a jumbo jet and the same weight as a small car, the Solar Impulse is a test model for a more advanced aircraft the team plans to build to circumnavigate the globe in 2015.<br/> <br />The aircraft runs on about the same power as a motor scooter, p
