Around the world in a solar-powered plane: pioneers get more ambitious
26 September 2014
Last year, two Swiss pilots became the first to take a manned flight across the United States in a featherweight, solar-powered plane (See: Solar powered plane lands in Washington in journey across US).
Now the same duo are back with a more ambitious plan - to fly an even more advanced solar airplane around the world early next year, with the flight beginning and ending in Abu Dhabi, UAE, which is sponsoring the effort.
The journey, like its cross-country predecessor, will not be continuous - more to meet the needs of the pilots than those of the plane, which, with an elaborate combination of solar cells and lithium batteries, can fly day and night.
State-backed clean-energy company Masdar said on Thursday that the Solar Impulse 2 will attempt its historic journey in March. Bertrand Piccard and Andre Borschberg, the project's founders and pilots, hope to complete the journey over four or five months, including stopovers.
The Solar Impulse 2 is powered by some 17,200 solar cells arrayed on wings that span 72 metres (236 feet). It is a larger version of a single-seat prototype that first flew five years ago. The founders say the plane in theory can stay airborne indefinitely.
In the earlier trip, the men flew roughly 24 hours before stopping. But this time they must fly for up to five days and nights at a time because of the ocean crossings.
''We trained in the simulator for longer times, for three or four days, but, of course, we never flew - that's going to be the first time,'' said Borschberg. ''You need an airplane which is reliable - you cannot do maintenance in-flight.''
Apart from Masdar, the mission has drawn support from dozens of entrepreneurs and companies, for the grand demonstration of the possibilities of clean energy.
But like many innovations, it has also had unexpected spin-offs for more immediate technologies, including a thin insulation that can allow refrigerators to have more internal space and a product developed with NASA that makes urine drinkable.
The pilots are also developing a way to produce oxygen with solar energy, but that will not be available until later flights, Borschberg said.
But, the men said, one of the biggest commercial applications for the plane itself could be as a kind of satellite replacement, making it into a sustainable high-altitude, unmanned platform with cameras or communications equipment.
Designing the plane, a carbon-fibre frame, with its array of solar cells and a sheer wrapping, has involved a relentless drive to reduce weight, Piccard, the other pilot, said.
The cockpit fits only one, so both men have developed techniques using yoga, meditation and self-hypnosis to rest or remain alert as necessary - including taking catnaps for no more than 20 minutes at a time, 10 or so times a day. The method worked so well that Borschberg even tried it on vacation, he said.
Still, the new model plane has more legroom than the previous version, and a reclining seat to make the journey more comfortable.
The pilots anticipate about 25 days of flying over a period of four to five months, stopping in Asia, the United States and Southern Europe or North Africa before returning to the United Arab Emirates.
The tour was the brainchild of Piccard, a psychiatrist who grew up in an exploration-oriented family and was part of the team that was first to circumnavigate the globe nonstop in a balloon. He became enamoured of the idea of flying without fuel when a propane shortage nearly ended the balloon ride in 1999.
He met Borschberg, an engineer and entrepreneur who had been a jet fighter pilot in the Swiss air force, after Piccard presented his idea to the Swiss Institute of Technology, which put Borschberg in charge of studying the project.
Sultan Ahmed al-Jaber, minister of state of the United Arab Emirates and the chief executive of Masdar, said the collaboration between the solar mission and his country was natural, given its investments in renewable energy and clean technologies.
Borschberg added that oil should be left to producing new materials, saying, ''It's a fabulous molecule.''