The trip had mechanical setbacks, and the plane's average speed would be legal on many American streets. But when the Solar Impulse aircraft touched down in Abu Dhabi in the early morning darkness Tuesday, it successfully completed a round-the-world voyage using only solar power.

Swiss pilots Bertrand Piccard and André Borschberg took turns flying the single-seat aircraft that began its historic trip on March 9 of 2015, flying more than 26,700 miles in a total of 17 stages (23 days) as they soared under the sun's power and then glided through the night.
When the Solar Impulse 2 airplane arrived in Spain from New York last month, it was greeted by the Spanish Eagle Patrol.

When the Solar Impulse 2 airplane arrived in Spain from New York last month, it was greeted by the Spanish Eagle Patrol.
Solar Impulse

"This is not only a first in the history of aviation; it's before all a first in the history of energy," Piccard said. "I'm sure that within 10 years we'll see electric airplanes transporting 50 passengers on short to medium haul flights."

"But it's not enough," Piccard added, saying that the solar technology that powered his plane can also be used on the ground to cut emissions in half.

The journey earned numerous records, including the trans-Pacific leg flown by Borschberg that took five days and nights, setting a mark for the longest solo flight in any airplane, according to the team behind Solar Impulse.
The path of Solar Impulse is shown in this graphic released by organizers of the sun-powered flight project.
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The path of Solar Impulse is shown in this graphic released by organizers of the sun-powered flight project.
Solar Impulse

Here are the stats on the flight's final leg from Cairo to Abu Dhabi:

Pilot: Bertrand Piccard
Flight time: 48 hours, 37 minutes
Maximum altitude: 28'000 feet (8'534 m)
Average speed: 34.5 mph (55.40 km/h)
Flight distance covered: 2'694 km (1'674 miles)

As Merrit reported for the Two-Way when Solar Impulse embarked on its final leg, organizers called it one of the most complex they'd undertaken, citing heat on the ground, thermal currents, and no-fly zones.

The plane and its crew also coped with challenging trans-oceanic flights, crossing the Pacific in two stages (including a stop for repairs in Hawaii) and crossing the Atlantic in 71 hours.

 Frazzled wrote:
Swiss pilots Bertrand Piccard and André Borschberg

 Orlanth wrote:
Solar power is gaining traction as an idea whose time has come.
Large recent improvements in electrical storage are key.

 feeder wrote:
Awesome. The sooner we can get all our energy needs from this giant thermonuclear reaction in the sky, the better.

Spetulhu wrote:
Don't get your hopes up yet. It's an impressive flight to be sure, but the plane can barely take any cargo beyond the pilot and his toothbrush. Add in how the support crew used commercial flights/ships and cars for everything and this little "solar powered" round-the-globe used way more fossil fuel than just putting the pilot on a regular jet around the world would have done.

I'd rather put my money on the next generation zeppelins under development. You can cover one of those in solar cells too, and they can actually take cargo to places you'd never even try landing a normal plane in.