Solar

Solar Plane Completes Cross-U.S. Flight

Late last Saturday night the solar-powered airplane Solar Impulse HB-SIA landed in New York, successfully concluding the last in its series of demonstration flights. This time the Swiss-made plane flew across the U.S., a total distance of 3,511 miles (5650 km).

André Borschberg, Solar Impulse co-founder and CEO, landed the plane at New York’s JFK airport at 11:09 p.m., three hours earlier than scheduled due to a tear in the fabric on the lower side of the left wing. The flight took 18 hours and 23 minutes.

“This last leg was especially difficult due to the damage of the fabric on the left wing,” said Borschberg. “It obliged the team to envisage all the possible scenarios, including bailing out over the Atlantic. But this type of problem is inherent to every experimental endeavour.” The team did not say what caused the tear.

The flight took off from Washington, D.C.’s Dulles airport shortly before 5:00 a.m. on Saturday and traveled at a top altitude of 10,200 feet (3,110 metres) with a top speed of 45 miles/hour (72 km/hour).  The plane was required to take off and land at off-peak times since it was flying along some of the busiest air traffic routes in the U.S.

Solar Impulse’s cross-country journey began on 3 May in San Francisco, Calif. In total, the plane flew for 105 hours and 41 minutes, day and night, at an average speed of 28.8 knots. Borschberg and co-founder Bertrand Piccard took turns flying the plane, stopping in Phoenix, Arizona; Dallas-Fort Worth, Texas; St. Louis, Missouri; Cincinnati, Ohio and Washington, D.C. In each city the team held public viewings and met with political leaders, including U.S. energy secretary Ernest Moniz, who called the plane “an engineering marvel.”

The Solar Impulse project is “advancing solar technology in many dimensions – flexible substrates, light weights — all important for lowering the cost of rooftop solar,” Moniz said. “A lot of people are going to be surprised 10 years from now at where solar is, and not only for standard applications but in types of solar that we don’t even know yet.”

The airplane, which its co-founders say took seven years to build, has a wingspan of 63.4 metres, equivalent to that of a massive Boeing 747 – but Solar Impulse, constructed from carbon fibre composite materials, weighs in at a mere 1.6 tonnes. Solar Impulse has 12,000 solar cells integrated into the upper wing surface, feeding power to four electric motors and charging the 400-kg lithium batteries during the day so that the plane can fly at night.

Moniz related the plane’s energy storage capability to the development of electric vehicles, mentioning Tesla‘s success. “We need to get battery costs down,” he said, “but these are technologies that are on the way. My message is, if you look at the Department of Energy’s research programme and technology vision, it involves many of the same kinds of technology. In 10 years we’ll see the fruits of all these technologies changing the world.”

From its home in Dübendorf, Switzerland, Solar Impulse took its first night flight on solar power in 2010, its first international flights to Belgium and France in 2011 and its first intercontinental crossing from Europe to Morocco in 2012. The HB-SIA will now be retired, the team says, and a larger two-seat plane, the HB-SIB, is planned to fly around the world in early 2015.

Lead image: Solar Impulse HB-SIA, © Solar Impulse

Video: Solar Impulse’s San Francisco flight, © Solar Impulse