ing average speeds above 30 mph (48 kph) and only slightly slower than the Solar Impulse.
The loud clicks of the Swiss plane's four propellers added another hint of nostalgia. And designers acknowledged the same worries that preoccupied the first fliers.
"The first crucial question was: Do we have enough power to fly?" said Borschberg. "The second crucial thing was: Are we capable of landing this airplane, is it controllable?"
"It was two hours of deep emotion," he added, calling the test flight the high point of seven years of work on the project. "The airplane has landed but we have not yet landed."
Borschberg followed the flight in a helicopter. Below waited numerous people involved with the project and Piccard, who comes from a long line of adventurers. His late father, Jacques, was an oceanographer and engineer who plunged deeper beneath the ocean than any other man. His grandfather Auguste, also an engineer, was the first man to take a balloon into the stratosphere.
On Wednesday, the Solar Impulse reached an altitude of 5,500 feet. After a gentle landing, Scherdel emerged from the cockpit with his arms raised, and the team broke open bottles of champagne.
When the plane attempts to circle the globe, the team will have to monitor conditions closely to ensure the aircraft follows the best weather. Ground crews will stay close to provide service at each stop, he said.
"Round-the-world will seem impossible until we do it," Piccard said. "Today is an absolutely incredible milestone."
At the pace of a fast bicycle, a solar-powered plane took to the skies over Switzerland for its maiden flight Wednesday. A round-the-world flight using a similar plane is planned for 2012.