October 2005

Solar Flier

Its aim: around the world on zero gallons

By David Talbot

Researchers at Solar Impulse in Lausanne, Switzerland, are designing a solar-powered, single-pilot aircraft they hope will circumnavigate the globe in 2010.

In order to generate enough electricity from photovoltaic panels on the tops of its wings, the craft will need a wingspan of 80 meters -- about that of the new superjumbo Airbus A380 jet; at the same time, however, its weight can't exceed 2,000 kilograms.

Meeting these constraints requires pushing the limits of materials and design and superoptimizing electrical components, batteries, and power management systems. Leading the plane's development is the Swiss adventurer Bertrand Piccard; in 1999, he and a partner became the first people to fly nonstop around the world in a balloon.

The new craft's basic design emerged from computer models built with help from the European Space Agency and the Swiss Federal Institute of Technology in Lausanne. The propulsion system alone required the modeling of some 100 parameters ranging from the pitch of the propellers to the diameter of the motors, says Yves Perriard, an electrical engineer at the Lausanne institute.

The plane will use composite structural parts and photovoltaics protected by a special polymer that allows them to function in temperatures as low as -60 degrees C and as high as 80 degrees C. Component prototyping is slated for next year, followed by manufacture in 2007 and the first test flight in 2008. Piccard's company has raised about one-third of the estimated $50 million cost of building the plane.