Solar Impulse-2 starts its first round-the-world flight

Swiss pilots Andre Borschberg and Bertrand Piccard today launched their first attempt to fly around the world in a plane using only solar power, from Abu Dhabi, in a landmark journey aimed at promoting green energy.

Last year, the two Swiss pilots became the first to take a manned flight across the United States in a featherweight, solar-powered plane (See: Solar powered plane lands in Washington in journey across US).

Now the same duo are back with a more ambitious plan - to fly an even more advanced solar airplane around the world early next year, with the flight beginning and ending in Abu Dhabi, UAE, which is sponsoring the effort. (Around the world in a solar-powered plane: pioneers get more ambitious).

The Solar Impulse 2 took off at 7:12 am, local time, from Al-Bateen airport and headed to Muscat, the capital of Oman, where it is expected to land later today after the first leg of the journey.

The takeoff, which was originally scheduled for Saturday, was delayed due to high winds.

From Muscat, it will cross the Arabian Sea to India before heading on to Myanmar, China, Hawaii and New York.

Solar Impulse-2 will make 12 stops on its epic journey spread over five months, with a total flight time of around 25 days.

Depending on the weather, they plan to fly to either southern Europe or North Africa and midwestern United States.

"This project is a human project, it is a human challenge," Borschberg, co-founder and chief executive of Solar Impulse, told reporters on Sunday.

Since the plane can hold only one person, Borschberg and Piccard will take turns to fly the plane, while the aircraft is able to fly on autopilot during rest breaks.

The biggest test for Borschberg and Piccard is the longest single leg non-stop flight for five days across the Pacific Ocean between Nanjing, China and Hawaii, a distance of 8,500 kilometres.

The revolutionary single-seater aircraft made of carbon fibre has a 72 meter wingspan (larger than that of the Boeing 747-8I) while its weight is just 2,300 kg, equivalent to that of a car.

The 17,000 solar cells built into the wing supply four electric motors (17.5 CV each) with renewable energy.

Though its wingspan is slightly bigger than that of a jumbo jet, its weight is around that of a sedan.

During the day, the solar cells recharge lithium batteries weighing 633 kg, allow the aircraft to fly at night.

This solar plane, which is the culmination of 13 years of research and testing by Borschberg and Piccard, will create history once it completes a round-the-world flight.

"We want to share our vision of a clean future," said Piccard, chairman of Solar Impulse, said of the mission.

"Climate change is a fantastic opportunity to bring in the market new green technologies that save energy, save natural resources of our planet, make profit, create jobs, and sustain growth."

Piccard, who hails from a family of scientist-adventurers and who in 1999 became the first person to circumnavigate the globe in a hot air balloon, believes that clean technology and renewable energy "can achieve the impossible".