PAYERNE: Swiss adventurer Bertrand Piccard’s team took its round-the-world solar plane prototype into the skies

for the first time today, with four propellers lifting the massive craft off the ground at near bicycle speed.

Piccard said the two-hour test flight would examine if the plane, with the wingspan of a Boeing 747 and the weight of a small car, could keep a straight trajectory. The team plans to fly it around the world next year.

“To fly without fuel, we have to make it fly in line,” said Piccard, who in 1999 co-piloted the first non-stop round-the-globe balloon flight. “There might be things that go wrong - maybe a technical problem, engine failure or a part breakdown,” he speculated.

At a military airport in the Swiss countryside, the “Solar Impulse” plane lifted off after only a short acceleration on the runway, reaching a speed no faster than 45 kmph. It slowly gained altitude above the green and beige fields, and disappeared into the horizon.