Solar aircraft lights the way

Bertrand Piccard, the president and pilot of the Swiss-based Solar Impulse project, plans to demonstrate the potential of alternative energy by flying a solar-powered aircraft around the world.

Bertrand Piccard

Mr Piccard addresses the summit at a plenary session tomorrow afternoon. q When was the Solar Impulse project conceived? a Following the around-the-world balloon flight in 1999. To achieve this success, we took off with almost four tonnes of liquid propane and landed with only 40kg. Realising that the lack of fuel could have made the mission fail, I made a promise to myself. The next time I'd fly around the world, I'd do it without fuel or polluting emissions. Orbiter III conveyed a great deal of enthusiasm. It is precisely this enthusiasm that must be mobilised to make people aware of the challenge of the 21st century: reconcile economic and ecologic interests, promoting the use of new technologies.

When will the flight take place? a We are now in the testing phase of the Solar Impulse HB-SIA, the first prototype of the project whose mission is to demonstrate this year the feasibility of a night flight propelled by only solar energy. After having analysed the recorded data of the first prototype, we'll build another aircraft with the objective of crossing the Atlantic and then flying around the world in 2012. The journey will start around May in order to get the maximum daylight.

Will it fly above cloud cover? a Yes, we'll have to stay above the clouds. During the day, the solar cells will provide the energy to run the four propellers at an altitude of 9,000 metres and at the same time charge the batteries for the following night. At the beginning of sunset, the aircraft will slowly glide down to 1,500m and then use the batteries to fly till the next morning, when it will climb back to 9,000m.

What do you hope to show? a There is clearly a future for unmanned solar drones. But more than that, Solar Impulse's objective is to show what can be achieved with new technologies in order to promote renewable energies and energy savings. It is all about saving energy. If an aircraft is able to fly day and night without fuel, propelled only by solar energy, let no one claim that it is impossible to do the same thing for motor vehicles, heating and air-conditioning systems and computers. This project voices our conviction that a pioneering spirit with political vision can together change behaviours in society and decrease the dependency on fossil energy.

Have any commercial applications emerged? a Solar Impulse has no commercial priorities; however, there have been several new technologies that have been developed in construction methods, new materials applications and system optimisations. And to help the pilot in his tasks of staying at the commands for several days and nights, Omega, one of the main partners of Solar Impulse with Solvay [a chemical and pharmaceutical group] and Deutsche Bank, specially developed an instrument that will help the pilot to keep the aircraft horizontal by informing him extremely precisely of the bank angle of the plane.

What were the technical issues? a In order to fly night and day propelled by only solar energy, we knew from the beginning that the aircraft would have to be very big to get enough surface to implement the solar cells and collect sufficient energy [the solar surface is 200 sq m]. At the same time, we needed to build an ultra-light aircraft to save the maximum energy to be able to fly through the night [it will weigh 1,600kg]. Each watt and each gram counted. We had to push the limits of technologies in every field. The result is breathtaking: an aircraft with the wingspan of an Airbus 340 [63.4m] and the weight of a midsize car [1,600kg], which flies with the average power of a small motorcycle.

Assuming the test flights are successful, what comes next? a Solar Impulse flew briefly for the first time in Dübendorf, near Zürich, on December 3. This year, we'll move the prototype to another airfield and proceed to higher test flights. Once the flight envelope is opened, we will proceed to the first complete day-night-day cycle, 36 hours, from next spring, followed by international flights of several days and nights. Why not in the United Arab Emirates? [e-mail]