Solar Plane Planned for Around-the-World Flight

Yancey Hall
for National Geographic News
April 7, 2005
Attempting aeronautical firsts is nothing new for Swiss adventurer Bertrand Piccard.

Coming from a family of explorers, he made history in March 1999 with a nonstop, around-the-world flight in a hot-air balloon, the Breitling Orbiter 3. Now Piccard has set his sights on another ambitious adventure: an around-the-world flight in a solar-powered airplane, the Solar Impulse.

The adventurer said his broader goal is to show the importance of "high technologies in sustainable development."

Piccard hopes his solar plane will be completely self-sustaining and capable of flying continuously, even at night, at altitudes up to 32,800 feet (10,000 meters).

The first test flight is set for 2007. The long-distance flights are scheduled to begin in 2009.

While any potential takeoff is still years away, the effort is already pushing Piccard and his 50-person team to develop an aircraft with state-of-the-art technology. Piccard plans to unveil their design in two months.

"The aircraft must be very rigid and will most likely be built with advanced carbon materials," Piccard said from Lausanne, Switzerland, during a recent telephone interview. "It will need to be very light and use very little energy at night. Energy storage is the biggest challenge for solar flight."

As with the Breitling Orbiter 3, Piccard will rely on a team of sponsors and engineers to assist him in developing the plane. The Swiss Federal Institute for Technology (EPFL) has signed on as the project's official scientific advisor. Other partners include the European Space Agency and Dassault Aviation—makers of the Falcon range of private jets.

"It's a huge project," Piccard conceded. "The plane will have an 80-meter (262-foot) wingspan, which is larger than any commercial aircraft."

Piccard estimates that enough power can be generated to sustain a flight of roughly 60 miles an hour (97 kilometers an hour). The batteries used to fly the plane at night must be incredibly dense, capable of storing 200 watts per kilogram (2.2 pounds).

Nearly the entire body of the plane will be covered by 287 square yards (240 square meters) of solar panels.

"This type of flight would not have been possible 15 years ago," Piccard said, referring to the new technologies, especially new-generation batteries, that are now available.

Past and Present Attempts

The idea of solar-powered flight first came to Piccard in 1997, during preparations for his around-the-world balloon flight attempt. In 2002 the adventurer began the solar flight program and in 2003 the first feasibility study was conducted.

"The results were extremely positive from that study," Piccard said. "After this we started to build the team, and we now have 50 people working on the project."

While Piccard's long-duration flight would be a first, other groups have already attempted solar-powered flight. NASA and its private-sector partner AeroVironment, Inc., have been trying for years to develop such an aircraft.

They achieved success in 1997 when the NASA Pathfinder—a lightweight, unmanned, flying wing—climbed to 71,500 feet (21,793 meters) under its own power.

In 2001 the remotely piloted Helios aircraft reached an altitude of some 96,863 feet (29,524 meters)—an unofficial world-record altitude flight for a solar plane.

But disaster struck two years year later. During a 2003 flight test, Helios experienced uncontrolled, up-and-down movement of its nose. The craft partially broke up in flight, then crashed into the Pacific Ocean near Hawaii.

"The loss of Helios was due to aerodynamic issues rather than any problem with the fuel cells or power output," said Alan Brown of NASA's Dryden Flight Research Center in Edwards, California.

Despite the setback, NASA continues to research solar-powered propulsion systems. The agency aims to rollout a series of prototype, demonstration aircraft over the next several decades.

"Helios was essentially a giant wing," Brown noted. "For future solar-electric aircraft, we will need further development of regenerative fuel cell and control systems for such aircraft."

NASA plans to launch its next solar-powered flight in 2009.

Why Solar Flight?

While the challenges for solar-powered flight are great, the potential benefits are equally so.

For Piccard, Solar Impulse is about showing how science and technology can be used for the development of renewable energy sources.

"We have to support the environment without threatening the world economy and our mobility," he said. "Solar Impulse will show that a win-win situation is possible."

The Swiss adventurer hopes to fly his as yet unbuilt, unproven solar-powered plane around the globe in stages, hopscotching the globe using designated landing sites.

At each stop Piccard plans to have press events to promote sustainable development, with representatives from government and scientific bodies in attendance.

If solar-powered planes prove successful, they would have many practical applications. This is especially true given their renewable energy source and theoretical ability for continuous flight.

Commercial applications could include using solar planes as telecommunications platforms, which would be capable of dispersing broadband media over wide areas.

As suborbital satellites, the high-flying planes could potentially be used for military reconnaissance and monitoring weather and other natural phenomena.

Regardless of the success or failure of Solar Impulse, Piccard may just well succeed in his larger goal: to generate dialogue on sustainable development technologies and to kick off a new century of aviation adventure.

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