Every day about 100.000 commercial flights cut through the skies. It means that in a year 300 billion liters of fuel are consumed, since only the fuel obtained from oil is able to give the necessary power to put in motion a plane big as a Boeing or an Airbus. Yet, in the last year a plane powered by another kind of energy has sailed the skies taking the first flight around the world and making history of renewable energy and aviation. It’s the plane Solar Impulse and its fuel is solar energy: the photoelectric cells positioned on the wings fed it during the day, while recharging batteries at night.
Its flight began on March 9, 2015 and ended with the landing in Abu Dhabi July 26, 2016, after traveling more than 42 thousand kilometers in almost 500 hours across four continents and 17 stopover. The Swiss project of the Federal Institute of Technology Lausanne, created with the aim of demonstrating that the possibility of circumnavigate the globe in 20-25 days was real, has been conceived in 2003 by Bertrand Piccard. He was the promoter with colleagues André Borschberg, Luigino Torrigiani and Brian Jones. A small team that over the years has expanded recalling fifty specialists and hundreds of external consultants. To establish the record of last 26th July it was necessary to investigate, try and experiment with the predecessor of the Solar Impulse, the HB-SIA prototype. The latter debuted with a flight of only 350m to about one meter above ground. Very little if compared to the kilometers needed to make the turn flow around the world, but it was 2009 and it was flying through solar energy. During the second test, a year later, the HB-SIA flied for two hours, conducted by pilot Markus Scherdel, to test the attitude of the ultra light aircraft to maintain a straight flight path. Another year passed and HB-SIA flies out from Swiss territory landing in Belgium. In the same year, 2011, the construction of the Solar Impulse begins delayed due to some structural failures during the trial test, until the launch in the skies of March 9, 2015 to demonstrate that we can live the planet without consuming all resources.
With a wingspan of 72 meters (like a Boeing 747) and a cabin equipped with supplemental oxygen, during its trip Solar Impulse followed a flight path next to the equator, which took place mainly in the northern hemisphere. Along the way it set numerous records including that of the longest length of solo flight by an airplane (117 hours and 52 minutes), obtained by André Borschberg during the flight from Japan to Hawaii, and the first crossing of the Atlantic Ocean on a solar airplane built by Bertrand Piccard. The next challenge is to see electric airplanes fly with fifty passengers on short and medium routes in ten years. However, many improvements remain to be made: nowadays Solar Impulse carries only one person, at an average speed of just 75 kilometers per hour. It’s not sufficient to simply enlarge the size to obtain a commercial aircraft powered by solar energy. We must get batteries with light traction and with high capacity, able to be the main source of energy for large vehicles for a few hours.