Solar Impulse has brought the dream of flying over long distances without the need for fossil fuel a step closer to reality.

Rethinking mobility

As the latest jewel in the Swiss technology crown, the solar-powered plane is designed to fly day and night without the need for fuel and without emitting harmful pollutants into the environment. For the transport sector which is confronted with the challenge of ensuring sustainable mobility, Solar Impulse amounts to a veritable revolution. Planes have long been the bugbear of ecologists, because one aircraft alone emits the same amount of pollutants as 500 cars equipped with a catalytic converter. A team of engineers and scientists from the Lausanne Federal Institute of Technology (EPFL), led by aeronautical engineer and pilot André Borschberg and psychiatrist and explorer Bertrand Piccard, are the brains behind this pioneering project.

Bertrand Piccard comes from a long line of explorers. His father Jacques was the first person to dive to the bottom of the Mariana Trench, the deepest part of the world’s oceans, (10,916 metres), while his grandfather Auguste was the first man to ascend into the stratosphere, giving him a bird’s eye view of the curvature of the Earth from his hot-air balloon. Bertrand too recorded a world-first, when in 1999 he circumnavigated the globe non-stop in a balloon. He intends to repeat his earlier pioneering achievement with the Solar Impulse, but this time without fuel.

A lightweight giant

After seven years of research, development and pilot projects, the HB-SIA, the first prototype of the one-seater Solar Impulse, successfully completed its first maiden flight in April 2010. The plane took off from Payerne aerodrome (canton of Vaud) and flew for just under two hours. The streamlined HB-SIA features a non-pressurised cockpit, is much lighter than a conventional aircraft (1,600kg) and has a similar wingspan to that of an Airbus A-340 (63.4 metres). Its wings are equipped with 12,000 photovoltaic solar panels which generate the electricity needed to supply the four 10hp electric engines during the day. The extra energy needed to fly at night comes from 400 kilos worth of lithium polymer batteries. The plane can reach an average speed of 70 km/h.

Circumnavigating the globe

Experiences with the HB-SIA will inform the construction of a second prototype, the HB-SIB. It will be equipped with a pressurised cockpit and state-of-the-art technology that will allow the aircraft to make long-haul, transoceanic flights. The plan is that the Solar Impulse plane will fly around the world in five stages. The flight trajectory will follow the line of the equator, but will primarily remain in the Northern hemisphere. During its voyage scheduled for 2013, the Solar Impulse will make a stopover in all five continents. These will allow a changeover of pilots and provide an opportunity to present the project to the public and to political and scientific institutions.