A Night Flight Powered by the Sun

Cross-Country Solar Plane Expedition Set for Takeoff

MOUNTAIN VIEW, Calif. â€" When Bertrand Piccard was growing up in Switzerland, heady discussions about the boundless potential for human endeavor were standard fare.

His grandfather, a physicist and friend of Albert Einstein and Marie Curie, had invented a special capsule so he and a partner could be first to reach the stratosphere in a balloon. His father, an engineer, helped design the submarine that made him and an American naval officer the first to plunge undersea to the earth’s crust.

“All the most incredible things seemed to be completely normal,” Mr. Piccard, a psychiatrist trained in hypnosis, said last week at Moffett Field at the NASA Ames Research Center here, preparing for his next expedition. “I thought this was the normal way to live and I was very disappointed to see that there are a lot of people who are afraid of the unknown, afraid of the doubts, afraid of the question marks.”

He went on to become part of the team that was first to circumnavigate the globe nonstop in a balloon. But when a propane shortage nearly ended his record-setting ride in 1999, he began dreaming of a way to fly day and night without fuel, an idea that has reached fruition in a featherweight solar airplane set for an initial voyage across the United States starting on Friday, weather permitting. His brainchild, the Solar Impulse, will not be the first sun-powered plane to fly; its chief distinction is its ability to go through the night.

Conceived of as a grand demonstration of what can be done with clean technologies â€" a Jules Verne-style adventure with a dash of P. T. Barnum thrown in â€" the project has more practical implications. While it could be decades, at least, before ordinary travelers line up to board solar electric planes, the technology is under consideration for drones, which risk damage each time they land to refuel.

Another venture’s solar electric plane, which seats two and could one day find a place in the sport aviation market, made its debut last week in Germany. The Sunseeker Duo from Solar Flight (founded by Eric Raymond, who also worked on the Solar Impulse project) can fly for about 12 hours at a time, said Eric Lentz-Gauthier, a pilot and spokesman for the company. And some of the technologies developed for Solar Impulse â€" which has a wingspan matching that of a 747 but the weight of a midsize car â€" are already set for commercial use, including the special batteries used to store the solar energy and the foam that insulates them.

The cockpit will fit only one, so Mr. Piccard will trade legs of the journey with his partner, André Borschberg, an engineer and entrepreneur who was a jet fighter pilot in the Swiss Air Force, flying at about 45 miles per hour for 18 to 20 hours at a time. The aircraft could theoretically fly continuously, but the pilots â€" despite Mr. Piccard’s apparent skill at self-hypnosis and Mr. Borschberg’s explorations of yoga and meditation â€" cannot.

“We have a sustainable airplane; now we have to build a sustainable pilot,” said Mr. Borschberg at a presentation at Stanford University later that day. So flight legs are limited, since the plane’s extreme sensitivity to turbulence demands a pilot’s direct attention.

The men plan stops in Phoenix, Dallas, St. Louis and Washington before a final landing at Kennedy Airport in New York around the end of June. The voyage is a precursor to a planned trip around the globe in 2015 for which the team is building a second plane, adding adjustments like an autopilot and reclining seat, to help them fly for as many as five days straight.

The two first met after Mr. Piccard presented his idea for fuel-free flight to the Swiss Institute of Technology, which put Mr. Borschberg in charge of studying the project. He ended up overseeing the aircraft’s design and construction, including its nearly 12,000 solar cells. Mr. Piccard turned to raising the $140 million in financing and sponsorship to support it (“Like in every couple, I was bringing the money in and André was spending it.”).

Solar Impulse borrows technologies from industries like semiconductor and boat manufacturing, Mr. Borschberg said. Constructed of a carbon fiber frame, monocrystalline silicon solar panels and a sheer, silver carbon wrapping, the plane is tough enough to reach almost 30,000 feet but so fragile you could put a finger through it.

“Everything is so efficient that we can fly only with the sun that we collect in the airplane,” he said.

For Mr. Piccard, the project represents another genealogical milestone. Like his grandfather and father before him, he is driven to be a pioneer.

A version of this article appeared in print on May 2, 2013, on page B1 of the New York edition with the headline: Solar Plane That Flies At Night.