After 12 years of calculations, simulations, construction and testing Bertrand Piccard and André Borschberg have launched Solar Impulse 2, their new single-seater solar aircraft set to fly around the world, without any fuel in 2015.
The Solar Impulse project has been created from an alliance between two men to complete a project deemed impossible by industry experts. While Bertrand Piccard, a psychiatrist and explorer, sourced partners to finance the project, engineer and entrepreneur André Borschberg brought together and led a technical team of 80.
To complete the flight, Solar Impulse 2 will have to fly without fuel with only one pilot for 5 consecutive days and nights over oceans from one continent to another. The single-seater solar aircraft has a huge wingspan of 72 metres (236 ft) for its weight of just 2,300 Kg (5’000 lbs.), producing an aerodynamic performance and energy efficiency greater than anything to date. There is a 3.8 m3 cockpit, every detail of which has been designed for a pilot to live there for a week. However, for the sake of maximum energy efficiency, the cabin is not pressurised or heated – a further endurance challenge for the pilot.
Bertrand Piccard, founder and Chairman of Solar Impulse said;
A vision counts for nothing unless it is backed up by action. With 8 world records for Solar Impulse 1, the first solar aircraft capable of flying during the night, crossing two continents and flying over the United States, we have shown that clean technologies and renewable energies can accomplish the impossible
For maximum efficiency carbon fibre and honeycomb sandwich has been used in the construction of the airframe while 140 carbon fibre ribs spaced at 50 cm intervals give the wing its aerodynamic cross-section, and also maintain its rigidity. 17,248 monocrystalline silicon cells each 135 microns thick mounted on the wings, fuselage and horizontal tailplane, providing the best compromise between lightness, flexibility and efficiency.
The energy from these cells are stored in lithium polymer batteries, whose energy density is optimized to 260 Wh / kg. Batteries insulated by high-density foam and mounted in the four engine nacelles, with a system to control charging thresholds and temperature. Their total mass amounts to 633kg, or just over a quarter of the aircraft’s all-up weight.
Test flights are due to take place in May, followed by training flights over Switzerland. The attempt to make the first round-the-world solar-powered flight is scheduled to start in March 2015 from Gulf area. Solar Impulse will fly, in order, over the Arabian Sea, India, Burma, China, the Pacific Ocean, the United States, the Atlantic Ocean and Southern Europe or North Africa before closing the loop by returning to the departure point. Landings will be made every few days to change pilots and organize public events for governments, schools and universities.