Researchers are preparing to unveil the prototype of a solar-powered aircraft which is intended eventually to conduct a transatlantic and round-the-world flight.
The Solar Impulse aircraft, under development for several years, will be shown off at Switzerland's Dubendorff Airfield on 26 June.
Tests of the Solar Impulse, construction of which began in 2007, are set to take place later this year with a view to performing a 36-hour zero-fuel flight in 2010.
It has a wing span of 61m (200ft) and four engines producing 30kW of power, enabling it to fly at about 38kt (70km/h).
The aircraft's single-pilot cockpit is unpressurised, limiting its altitude to 8,500m (27,900ft), but the prototype is intended purely as a validation and experimentation platform.
"Current solar aircraft are not designed to store energy and therefore have to land in cases of insufficient sunlight," says the development team.
"To demonstrate the formidable potential of renewable energies, Solar Impulse intends to place the bar much higher and have a piloted aircraft fly night and day without fuel."
This can only be achieved, says the team, by a "drastic reduction" in energy consumption.
Solar Impulse was launched by pilot Bertrand Piccard and the project's co-founder Andre Borschberg. Piccard was one of the pilots of the Breitling Orbiter 3 expedition which performed the first non-stop circumnavigation of the Earth by balloon.
The solar-powered aircraft programme has been backed by primary sponsors Deutsche Bank, Omega and Solvay.
If the trials are successful a second aircraft will be built to attempt several consecutive 24-hour cycles and a transatlantic crossing around 2012.