Building a solar-powered dream
It has the wingspan of a commercial airliner, the weight of an automobile and solar panels to provide enough electricity to light a very large Christmas tree.
If this strange contraption actually flies, for some it will be as great a feat as anything achieved at the 2008 Olympics.
Bertrand Piccard, a Swiss psychiatrist best known for his 1999 trip around the world in a balloon, is trying to repeat the journey in a solar-powered airplane. He and a partner, Swiss engineer Andre Borschberg, came to promote the project at the Olympics, hoping to raise money -- though they won’t say how much the project will cost -- to obtain technical assistance and, if nothing else, secure landing rights from the Chinese government.
Their ambitions go far beyond getting their airplane off the ground. They see the craft as something of a billboard promoting solar energy.
Piccard’s around-the-world journey in 1999 relied not only on wind, but propane gas -- 4 tons was used to keep the balloon aloft.
“It gave me the wish to fly around the world with no fuel,” he said last week during a talk with reporters. “If you could fly around the world without the fear of running out of fuel, you would have a freedom that is almost perpetual.”
In 1981, U.S. engineer Paul MacCready flew a solar-powered airplane across the English Channel and inventors have been tinkering with the technology ever since. But previous models of solar planes could fly only by day.
“They showed mostly the limits of solar energy rather than the potential,” Borschberg said.
Piccard and Borschberg are developing a prototype at a former military base in Dubendorf, Switzerland. Its wings, which span about 198 feet, are covered with photovoltaic cells to convert sunlight into electricity. At night, the plane will run on excess electricity stored in batteries. The engineering challenge is to generate enough power to fly the plane and charge the batteries and to keep the weight under 3,500 pounds, about the same as a mid-size car.
“To fly day and night, we need a very efficient aircraft,” Borschberg said.
A replica of the aircraft is on display at an Olympic pavilion sponsored by Omega, the Swiss watch company, which is one of the benefactors of the project. Suspended from the ceiling, the plane gets quizzical, sometimes skeptical looks.
“I think it will be a challenge. You have to make all the parts small enough and light enough. But if they can do that, it will fly,” said You Changfu, a specialist in solar energy at Beijing’s Qinghua University.
Piccard and Borschberg hope to conduct a test run of the single-pilot plane in the spring and by 2011 have a slightly larger two-pilot version to fly around the world.
The plane should be able to fly perpetually, unlike its pilots. When circumnavigating the globe, the pilots will have to land every few days to replenish food, water and oxygen.
To keep the airplane light, Piccard and his team said, the pilots will have few creature comforts. During the day, the plane is expected to climb to nearly 30,000 feet, but by night it should glide at about 6,500 feet to conserve battery life. Average speed will be 42 mph to conserve electricity. The journey will run west to east, against the direction of Earth’s rotation, to maximize exposure to sunlight.
With such limitations, it will be a long haul before the solar-powered plane has any practical use.
But Piccard, 50, who comes from a family of adventurers, sees his plane not so much as a vehicle for getting from, say, Zurich to Beijing, but as a metaphor for renewable energy.
“The pilot will have one goal -- to reach the next sunrise before his batteries are empty. If his batteries are empty sooner, the plane will not be able to land and it will crash,” Piccard said. “If we don’t find a renewable source of energy before sunrise, our economy will crash.”