You are here

Solar Impulse 2: the round-the-world aircraft is completed

News International-French

11 Apr 2014

Bertrand Piccard and André Borschberg launched Solar Impulse 2, their new single-seater solar aircraft designed to take up the challenge of the first round-the-world solar flight, without any fuel in 2015.

Solar Impulse is the product of an alliance between two men to fulfill a project deemed impossible by industry experts. While Bertrand Piccard, a psychiatrist and explorer, sourced partners to finance the project and promoted the cause for clean technologies (subsequently endorsed by many political authorities), engineer and entrepreneur André Borschberg brought together and led a technical team of 80. It has taken 12 years of calculations, simulations, construction and testing to arrive at launch of Solar Impulse 2.

To complete the round-the-world flight, Solar Impulse 2 will have to accomplish what no other aircraft has achieved before: flying without fuel with only one pilot for 5 consecutive days and nights over oceans from one continent to another. This is the challenge for which the aircraft has been built. The single-seater solar aircraft has a huge wingspan of 72 meters (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 pressurized or heated – a further endurance challenge for the pilot.

Decision supplies Solar Impulse HB-SIB large carbon parts

The swiss company is the supplier of Solar Impulse HB-SIB large carbon parts as wing spar, fuselage, cockpit, tail structure and more.

The chances of succeeding at the first attempt to build a solar airplane capable of flying around the world were judged to be slim, so a more rudimentary prototype, HB-SIA, was first constructed.

Lessons learned from this prototype are incorporated in the second airplane, to be registered as HB-SIB, construction of which was started in 2011. Its more spacious cockpit will enable the pilot to fully recline during flights lasting from 4 to 6 days; it will have an increased payload; its electrical circuitry will be isolated to enable flights in rain; and system redundancy will improve reliability.

Whereas the prototype uses existing technologies, Solar Impulse HB-SIB requires the development of new materials and new construction methods. Solvay has invented electrolytes that allow the energy density of the batteries to be increased; Bayer MaterialScience is allowing the project to make use of its nanotechnologies; and Décision is using carbon fibers that are lighter in weight than any previously seen

The first wing spar section was delivered to Dübendorf in March 2012. However, during the final test of this central part, the structure of the wing spar succumbed to the load and broke. The initial shock soon turned out to be an opportunity: the flight around the world had to be postponed which opened the door for going to the United States and completing the epic journey across America.

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.

More information: