Solar Impulse 2 Begins Its Milestone Flight around the World

On Tuesday night, the Solar Impulse 2, powered entirely by solar energy and lithium backup batteries, finished the second leg of its journey — a shortish hop from Oman — by gracefully touching down on the runway as handlers rushed up and steadied the long wing tips, guiding the slender craft up to an awaiting media frenzy at India's Sardar Vallabhbhai Patel International Airport in Ahmedabad. (Follow along on the team's blog.)

This unique craft began its around-the-world journey in Abu Dhabi on Monday, and uneventfully landed in Muscat, Oman later the same day. Andre Borschberg, the Solar Impulse co-founder (see earlier interview), was at the cramped controls when it took off. Originally scheduled for Saturday but delayed by high winds, this first leg capped 13 years of research and testing by Borschberg and co-founder pilot Bertrand Piccard (see his earlier interview).

A short layover

On early Wednesday morning, the famous aircraft sat in a special hanger as its ground crew scrutinized reams of flight data for any problems, reporters tweeted and live-blogged status updates to a world audience. After completing the scheduled four-day repair stopover, the wing's 17,000 SunPower solar cells will allow the craft to quietly lift off and soar to Varanasi.

Tested over 21 times, Si2's first flight took off last June and soared above the Swiss Alps. 

The global logistics

SI2 is scheduled to make 12 layovers during its 25,000 mile journey, hop-scotching through China and Myanmar before crossing the Pacific Ocean, where it will land in Hawaii, gateway to the US Midwest and East Coast. It will finally make a return flight across the Atlantic Ocean. Since stormy weather - particularly strong head winds - can severly effect the performance of the light craft, it may make unscheduled stops in southern Europe or North Africa.

Both pilots have been training for the journey's 25 flight days (see video). The longer flights will push their endurance to extremes (echoes of Charles Lindberg), especially then they fight to stay alert during the two five-day trips over the Pacific and Atlantic oceans. Assisting the pilots, the plane's computer can sound an alarm if anything unusual happens, allowing undisturbed 20-minute power naps. The pilot also wears a visor that flashes if anything requires his immediate attention, and a special armband vibrates if the plane pitches more than five degrees.

Anyone can follow the flights, including ground control video coverage at

Does the sucess of SI 2 help make solar more acceptable?