MOUNTAIN VIEW-A groundbreaking solar-powered Swiss aircraft is ready to make a coast-to-coast flight across the United States, its creators said. The experimental Solar Impulse plane, which has made several trips since its maiden flight in 2009, will take off on May 1 on a transcontinental tour split in five stages. “We are ready to do this flight across America,” said Solar Impulse co-founder Andre Borschberg during a press conference at a hangar in Mountain View, near San Francisco.