On 7 July, pilot André Borschberg flew the aircraft for a whole day, and then through the entire night, powered only by solar energy stored during the day.
The complete flight lasted 26 hours and 9 minutes. The plane achieved an average speed of 23 knots and maximum altitude of 8564 m (above sea level).
"I've been a pilot for 40 years now, but this flight has been the most incredible one of my flying career," said Borschberg, CEO and co-founder of the Solar Impulse project. "Just sitting there and watching the battery charge level rise and rise thanks to the sun … and then that suspense, not knowing whether we were going to manage to stay up in the air the whole night. And finally the joy of seeing the sun rise and feeling the energy beginning to circulate in the solar panels again!”
“I have just flown more than 26 hours without using a drop of fuel and without causing any pollution!”
Solar Impulse has a wingspan of 64 m and is powered by 12 000 solar cells. The aircraft is constructed around a skeleton of carbon fibre/honeycomb composites in a sandwich assembly. The upper wing surface is covered with a skin of encapsulated solar cells and the underside with lightweight flexible film. Between these two surfaces, 120 carbon fibre ribs at 50 cm intervals profile these two layers and give the wing its aerodynamic shape.
The next challenge for Solar Impulse will be crossing the Atlantic and an around the world flight, using a second prototype which goes into construction this summer.