Solar Impulse plane leaves Oklahoma for Dayton

Washington: A solar powered aircraft embarked Saturday on the latest leg of an around-the-world journey designed to showcase what clean energy can do, taking off from Tulsa, Oklahoma for Dayton, Ohio, the cradle of US aviation.

The Solar Impulse 2, piloted by Swiss businessman Andre Borschberg, was due to arrive at 11:00 pm (0300 GMT Sunday) at Dayton International Airport after an 18 hour flight up and across the agricultural midsection of the United States.

The slow moving, single seater plane with the wingspan of a Boeing 747 cuts a flimsy figure, but it has traversed much of globe in stages since taking off March 9, 2015 from Abu Dhabi.

The aircraft is clad in thousands of solar cells, the sole source of energy for the flight.

Traveling at average speeds of only 30 miles (48 kilometers) per hour, it will take much longer to reach Dayton in Solar Impulse 2 than in a car, with the typical road trip from Tulsa estimated at 12 hours.

The flight to Dayton is the 12th leg of Solar Impulse's projected 16-leg east-west circumnavigation, with Borschberg and Bertrand Piccard alternating as pilots.

Piccard is the Swiss psychiatrist and balloonist who initiated the project.

"The flight is part of the attempt to achieve the first ever Round-The-World Solar Flight, the goal of which is to demonstrate how modern clean technologies can achieve the impossible," they said in a statement.

"Watching Si2 silently lift off is beautiful. Science fiction in reality!" a logbook comment said on the project's website.

Dayton is significant to aviation buffs because it is the home of Orville and Wilbur Wright, brothers who developed the world's first successful aircraft.

Six hours into the flight, the plane had crossed into Missouri and had successfully maneuvered through strong northwest winds.

It departed from Tulsa International Airport at 4:22 am (0922 GMT).

Thanks to an inflatable mobile hangar, which can be packed up quickly and transported, Solar Impulse 2 can be sheltered at a variety of locations.

The aircraft was grounded in July when its batteries were damaged halfway through its 21,700-mile (35,000-kilometer) circumnavigation of the globe.

The crew took several months to repair the damage caused by high tropical temperatures during a 4,000-mile flight between Nagoya, Japan and Hawaii.

The plane was flown on that stage by Borschberg, whose 118-hour journey smashed the previous record of 76 hours and 45 minutes set by US adventurer Steve Fossett in 2006.

He took 20-minute catnaps to maintain control of the pioneering plane during the flight from Japan, in what his team described as "difficult" conditions.

- How it works -

The Solar Impulse 2, which weighs roughly the same as a family car, contains 17,000 solar cells that power the aircraft's propellers and charge batteries.

At night it runs on stored energy.

The plane's typical flight speed can increase to double that when exposed to full sunlight.

After crossing the United States, the pilots are set to make a transatlantic flight to Europe, from where they plan to make their way back to their point of departure in Abu Dhabi.

Piccard, a doctor by training, completed the first non-stop round-the-world balloon flight in 1999.

His teammate Borschberg is no stranger to adventure -- 15 years ago he narrowly escaped an avalanche, and in 2013 he survived a helicopter crash with just minor injuries.