The Swiss solar-powered plane Solar Impulse 2 took off from Oman and headed for India last week. The mission of its two-man crew—pilots Bertrand Piccard and Andre Borcheberg—is to complete the first round-the-world flight with a fixed-wing aircraft using only solar power. The first iteration of Solar Impulse, which broke records for height and distanced traveled by a solar-powered plane, was also a project led and privately funded by Piccard and Borcheberg; SI was a single-seat plane that had the ability to stay aloft for up to 36 hours at a time. Having completed flight missions in Europe and the US, Piccard and Borcheberg later built upon the experience of their first prototype in the design and construction of SI2, which took 12 years.
Only slightly larger than its predecessor, SI2 has a wingspan slightly less than that of an Airbus A380, the world’s largest commercial airliner. In contrast to the bulky A380, SI2 weighs in at 5,100 lb, which is about the weight of an average car. Improvements from its predecessor include a larger cockpit and more advanced avionics, which provide the crew with an autopilot option. Additionally, environmental support systems allow for flight at 39,000 feet. SI2 is able to fly at speeds between 30 and 60 miles per hour for five consecutive days and nights without a single drop of oil by utilizing lithium ion batteries powered by its 17,000 solar cells during day. Flying at an average speed of 30 knots, SI2’s crew will alternate piloting responsibilities in their mission to circumnavigate the globe in 25 flight days.
With its point of origin in United Arab Emirates, SI2’s itinerary includes the following destinations: UAE, Oman, India, Myanmar, China, the US, and a yet to be determined location in southern Europe, after which the plane will return to its starting point. SI2 has already bested the world record for longest flight distance flown by a solar-powered plane, which was previously set by SI, in its 912-mile flight from Oman to India. The longest leg of the trip, however, is yet to come; SI2 is scheduled to travel across the Pacific from Nanjing, China to Hawaii. SI2 has been grounded for several days in Ahmedabad, India, due to unfavorable weather conditions.
In addition to their quest to circumnavigate the globe on SI2, Piccard and Borcheberg also hope to draw attention to renewable energy technologies that will allow for decreased dependence on fossil fuel.