The Solar Impulse aircraft, a Swiss bid to fly around the world on solar energy, will make its first test flight Wednesday at a military airbase in western Switzerland, organisers said.
After several delays due to unfavourable weather conditions, the flight by prototype is now scheduled at 9.00 am (0700 GMT) on April 7, said a spokesman from the project co-founded by Swiss pilot and explorer Bertrand Piccard and engineer Andre Borschberg.
Wednesday's flight at Payerne airbase is expected to last around one and a half hours, reaching an altitude of about 1,000 metres (3,280 feet), the organisers added in a statement.
The prototype, which is slightly smaller than the plane that will undertake the round-the-world flight, has a wingspan comparable to that of an Airbus A340 airliner but weighs as little as a family-sized car at only 1,600 kilogrammes (3,527 pounds).
It had briefly taken off for the first time in December for a controlled 400 metre hop about one metre above the runway.
The tests are due to build up to a first non-stop 36 hour flight through darkness, followed by a five-stage flight around the world in 2012.
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