THE HISTORY OF SOLAR AVIATION
 |
The Solar Impulse is not the first solar airplane imagined by man, but it is certainly the most ambitious. None of its predecessors has ever managed to make an entire night flight with a pilot on board... Solar aviation began with reduced models in the 1970s, when affordable solar cells appeared on the market. But it was not until 1980 that the first human flights were realised. In the United States, Paul MacCready's team developed the Gossamer Penguin, which opened up the way for the Solar Challenger. This aircraft, with a maximum power of 2.5 kW, succeeded in crossing the Channel in 1981 and in quick succession covered distances of several hundred kilometres with an endurance of several hours. In Europe, during this time, Günter Rochelt was making his first flights with the Solair 1 fitted with 2500 photovoltaic cells, allowing the generation of a maximum power of 2.2kW. In 1990, the American Eric Raymond crossed the United States with Sunseeker in 21 stages over almost two months. The longest lap was 400 kilometres. The Sunseeker was a solar motor bike-sail plane with a smoothness of 30 for a tare weight of 89 kg and was equipped with solar cells of amorphous silicon. In the middle of the 1990s, several airplanes were built to participate in the "Berblinger" competition. The aim was to be able to go up to an altitude of 450m with the aid of batteries and to maintain a horizontal flight with the power of at least 500W/m2 of solar energy, which corresponds to about half of the power emitted by the sun at midday on the equator. The prize was won in 1996 by Professeur Voit-Nitschmann's team of Stuttgart University, with Icare 2 (25 meters wingspan with a surface of 26 m2 of solar cells.) Even if it did not allow a pilot on board, one could not forget Helios, developed by the American AeroVironment Society on behalf of NASA. This remote controlled aircraft, with a wingspan of more than 70 meters, established a record altitude of nearly 30'000 meters in 2001. It was destroyed during a flight two years later, probably because of turbulence, and crashed in the Pacific Ocean. In 2005, Alan Cocconi (picture), founder of AC Propulsion, succeeded in flying an unmanned airplane with a 5-meter wingspan for 48 hours non-stop, propelled entirely by solar energy. This was the first time an airplane of this type was able to fly through a whole night, thanks to the energy collected by, and stored in, the solar batteries mounted on the plane. "The pioneer is not always the one who succeeds, but the one who is not scared to fail." Bertrand Piccard |