It takes a Boeing 747 about 10 hours and 36,000 gallons of fuel to fly from eastern China to Hawaii. As soon as Tuesday, André Borschberg will attempt the same flight in a high-tech, sun-powered aircraft that resembles a dragonfly. He’ll do it over five days, without a drop of fuel.
No one before has attempted a solar-powered flight over such a large expanse of ocean – 5,070 miles. If bad weather or other problems force him to ditch his Solar Impulse plane, Borschberg will have only his wits and a life raft to save him.
Borschberg acknowledges the dangers. So does his fellow Swiss adventurer, Bertrand Piccard, who flew the single-seat plane to China in April and is slated to fly it from Hawaii to Phoenix later this month.
“Yes, we are nervous. I am nervous also,” Piccard said in an interview in Nanjing. “But more than anything, we are impressed. We’re in awe of the enormous distance over water that we have to do: André for the first part, and me for the second part.”
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Piccard and Borschberg hope to be the first pilots to fly a solar-powered plane around the world. After 12 years of planning, networking and fundraising, they launched their tag-team expedition in March, flying from the United Arab Emirates to Oman, and then on to India, Myanmar, Chongqing, China, and Nanjing.
On Wednesday, scores of Chinese students filed into a portable hanger in Nanjing, a city of 8 million people, to meet the pilots and take a look at their odd-looking craft. The students gawked at the enormous wingspan of the Solar Impulse – at 236 feet, wider than that of a 747.
Despite its size, the plane weighs only 5,071 pounds, about as much as a minivan. Much of that weight comes from the four batteries that sit behind four propellers. When the plane is in flight, those batteries are recharged by 17,248 feather-light solar cells on top of the wings. The batteries then help power the aircraft at night.
Flying the plane is complex. To husband its power, the pilot takes the aircraft as high as possible during the late daylight hours. Then, in the darkness, the plane’s engines are turned off and the aircraft sails like a glider, dropping slowly for about three hours. Then the engines are turned back on, drawing on the batteries until daybreak.
“It is difficult to fly, especially at the beginning,” said Borschberg, a 62-year-old former fighter pilot with the Swiss air reserve. With its lightness and wide wingspan, the plane reacts slowly to a change in controls, making it easy for a pilot to overcompensate, he said.
Some aviation experts have mocked the plane’s slowness; it has a top cruising speed of about 80 mph. Piccard said such critics were missing the point. The goal of Solar Impulse isn’t to set speed records. It’s to demonstrate that a plane can fly around the world without a gas tank and, theoretically, with the sun’s rays, keep flying forever.
“We really want to prove that energy efficiency, solar power and modern technology can achieve the impossible,” Piccard said.
A lean 57-year-old with piercing gray-blue eyes, Piccard initially launched Solar Impulse, in part, to continue a family legacy of invention and exploration. In 1960, his father, Jacques Piccard, became the first person to reach the bottom of the Mariana Trench. He did it with partner Don Walsh in a submersible that his own father, physicist Auguste Piccard, had helped design.
Bertrand Piccard grew up around space program celebrities when he lived in West Palm Beach, Fla., where his father worked as a U.S. Navy contractor. Visitors to the house, he said, included aerospace engineer Wernher von Braun along with Neil Armstrong, Buzz Aldrin and other NASA astronauts.
Those encounters, said Piccard, fanned his interest in air expeditions. Later the experience would lead him to master hang gliding, micro-light aircraft and hot-air balloons.
His big break came in 1999, when he and co-pilot Brian Jones became the first to circle the globe nonstop in a hot-air balloon. For Piccard, after two failed attempts, the 19-day trip was a triumph but also a nail-biter. In the final hours, he and Jones nearly ran out of fuel, partly because their balloon had stalled over the Pacific, burning gas to stay aloft above the windless sea.
“It was then that I thought about the next big flight,” he recalled. “It has to be with no fuel.”
Piccard presented his initial concept of Solar Impulse to the Swiss Federal Institute of Technology, which chose Borschberg, an engineer, to examine it. Borschberg eventually became Piccard’s collaborator and Solar Impulse CEO. The two assembled a design team and lined up sponsors and partners. Scores of companies, ranging from Omega to Google, have since contributed to Solar Impulse, either by donating materials or expertise.
One big challenge for the Solar Impulse pilots is the amount of time they must spend, individually, aloft in the unpressurized cockpit, with only infrequent 20-minute naps. Borschberg said the plane, with its lightness and vulnerability to wind changes, couldn’t be on autopilot for any longer than that.
To prepare for those lonely days aloft, the pilots practiced with a flight simulator, and they’ve developed mental exercises to help themselves stay alert. Borschberg is a long-standing practitioner of yoga, partly to clear his thoughts. Piccard, a licensed psychiatrist, has practiced self-hypnosis for many years.
“What you try to do is visualize all the potential disasters that could happen, and then think, what are the solutions?” said Piccard. “You try to visualize yourself in that experience. . . . That way, if something disastrous happens, you can react without panic. That is really very important.”
Borschberg said the first possible opening for him flying to Hawaii would be Tuesday, but if the “weather window” isn’t good, he’ll wait for a better date. The crew is ready for surprises. After Piccard landed Solar Impulse in Chongqing a month ago, the team had planned on being there just a few days, but bad weather grounded them for three weeks.
Although Solar Impulse bills itself as a carbon-free aircraft, the entire operation can’t make that claim. Some 160 people are involved, both traveling with the plane and in Monaco, where a mission-control team is based. Support equipment and crew are flown on cargo planes, generating the same emissions as any other large aircraft.
Piccard makes no apologies for that. He said technology would advance only if it built on the backs of previous innovations.
“I am not someone who wants to go back in the caves with candles,” he said. “The psychology of human beings is not to go backward; it is to go forward. But we can go forward in a clean way.”
While the two pilots said they weren’t trying to revolutionize aviation, they note that the Wright Brothers similarly flew on single-seater planes that were very slow. Although those aviation pioneers were initially mocked, their first flights inspired others, leading to the development of the first passenger airplanes.
The lesson? “Never underestimate the power of technology development,” said Piccard. “We should embrace it.”