Solar-powered composite plane makes maiden flight

Solar Impulse, the brainchild of adventurer Bertrand Piccard and CEO/project cofounder Andre Borschberg, took flight on April 7 at the Payerne airfield in Switzerland, after seven years of research and development.

Solar Impulse, the brainchild of adventurer Bertrand Piccard and CEO/project cofounder Andre Borschberg, took flight on April 7 at the Payerne airfield in Switzerland, after seven years of research and development. Weighing only 1,600kg/3,527 lb yet boasting an enormous wingspan (63.4m/208 ft), the plane took off at less than 40 kmh/25 mph and stayed aloft for 87 minutes, powered only by solar energy. Test pilot Markus Scherdel executed basic maneuvers and landed successfully.

The craft’s extremely low weight owes much to its carbon fiber composite airframe. A carbon composite/honeycomb sandwich box beam forms the fuselage. The wing structure comprises 120 carbon/epoxy ribs, at 50 cm/20 inches each. Its flexible upper wingskin contains 10,748 encapsulated solar cells, while the lower skin is a flexible film material. The solar cells feed lithium polymer batteries in four small pods, each fitted with a 10-hp electric motor and propeller. Project partner Bayer MaterialScience AG (Leverkusen, Germany), provided its trademarked Baytubes carbon nanotube (CNT) material, adhesives, polyurethane rigid foams for paneling in the cockpit and engine, and the extremely thin polycarbonate films and sheet for the cockpit glazing as well as technical expertise. Other principal technology partners included Solvay (Brussels, Belgium), ALTRAN Group (Levallois-Perret, France) and Dassault Aviation (Paris, France).

After further tests, including night flights this summer, a second plane will be designed and built for an around-the-world flight, scheduled in 2013.