The First Solar-Powered Flight Around the World

Bertrand Piccard landed in Abu Dhabi on July 25th at 8:05 p.m. EDT (Easter Daylight Savings Time) after completing a two-day solo flight in the airplane, Solar Impulse 2 (SI2), an aircraft powered 100 percent by solar power. The journey marked the end of the first circumnavigation of the Earth in a solar-powered airplane.

The plane

The idea of the SI2 came to Piccard, the project’s initiator and chairman, in 1999 after he flew around the world in a hot air balloon that relied on 3.7 tons of liquid propane. He wanted to do it again but this time without the use of fossil fuels. In 2002, Piccard announced the project and soon after met Andre Borschberg, an engineer and professional pilot, who led the SI2’s feasibility tests. The two have worked together on the project ever since.

The SI2 has a 236-foot wingspan and weighs about 2.3 tons (about the same as a car). It has four propellers and four batteries, and its wings are covered in 17,248 solar cells. The solar cells take energy from the sun during the day to charge the batteries and run the motors, and the batteries power the plane through the night.  

Around the world in 504 days

The 24,800-mile trip was accomplished in 17 separate flights, which took 23 days in the air over the course of a year and a half. Piccard and Borschberg took turns completing the flights in the one-man plane. They covered four continents, nine countries and two oceans, and made a stop in Dayton, Ohio—the Wright brothers’ hometown. They broke 19 official aviation records along the way. No fuel was ever used.

The SI2 took off on Mar. 9th, 2015 and successfully completed six legs of its journey by the end of May. However, while crossing the Pacific Ocean on May 31, inclement weather forced Borschberg to make an unplanned stop in Nagoya, Japan. Further weather problems kept the team grounded for another month.

Finally, the crew crossed the Pacific Ocean on June 28th. Borschberg spent 117 hours and 52 minutes in the air between Japan and Hawaii, breaking the world records for distance and duration for solar aviation and for longest solo flight ever.

During this flight SI2’s batteries overheated and needed to be replaced, halting the trip at the halfway point for months. After the plane had been repaired the team had to wait again for the clear skies and long days of the 2016 summer season.

After a long hiatus, Borschberg and Piccard were able to take off again, and between April and July of this year they completed the final nine legs of their circumnavigation.

They finished where they had begun, in Abu Dhabi, bringing a 16-month flight and a 13-year project to a close.

To learn more about Solar Impulse 2, visit www.solarimpulse.com/adventure.

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