NEW YORK – The technologies used in a high-profile solar airplane could lead to some unexpected spinoffs, including lighter-weight building materials, longer-lasting batteries and better refrigerators, the plane's creators say.
Solar Impulse 's HB-SIA, an entirely solar-powered plane that can fly at night, will feature several new technologies with applications elsewhere, Solar Impulse team members told TechNewsDaily on Dec. 12.
The team, including engineer André Borschberg and explorer Bertrand Piccard, was visiting New York from Switzerland to secure permissions for a coast-to-coast flight across the U.S. They want to make the U.S. flight in May and June 2013, and circumnavigate the globe in 2015.
A Solar Impulse plane made news in 2010 after flying for 26 hours entirely on solar energy. The plane harvested power from the solar cells that make up the upper surface of its enormous wings. Since then, the HB-SIA has flown from Europe to Africa, requiring several stops along the way.
The plane usually flies about 20 hours at a time, traveling about 43 mph (70 kilometers per hour). It can't fly much longer than that, in part because its pilot cannot stand or sleep during the flight, and in part because its light construction can't withstand high winds, so it must land often and wait for fair weather. Borschberg, Piccard and others trade off piloting.
Many of Solar Impulse's spinoff technologies help keep HB-SIA ultra-light. The plane weighs about 3,500 pounds (1,600 kilos), or about the weight of an average car, so there's no space for extras. There's not even a separate bathroom. The pilot's seat — the only seat — doubles as a toilet.
The plane's body is made of carbon fiber sheets that are three times lighter than paper. Such sheets could go into other aircraft, cars and other ground vehicles, or houses, Alexandra Gindroz, a Solar Impulse spokesperson, said. [SEE ALSO: 10 Building Materials from the Future ]
Many of the plane's parts, including screws, bolts and hinges, are made from plastic instead of metal to save weight. Solvay, a chemical company and one of Solar Impulse's dozens of corporate partners, is now selling the lightweight screws to car and electronics companies.
Because of its low weight requirement, the plane doesn't have climate control. So pilots depend on the cockpit's insulation to withstand the extreme heat and cold they encounter at 30,000 feet. Bayer MaterialScience made the plane's insulation and will put the same material into 75 percent of the new refrigerators it makes in 2013, Piccard said.
The plane also carries efficient, lithium-ion batteries that collect charge from the plane's solar cells during the day. Because of its batteries, HB-SIA ends a sunny day with more fuel than when it started, unlike fossil fuel-powered planes.
"You could have flown the entire day and given [extra electricity] back to the grid," Borschberg said. During Solar Impulse project flights, that excess energy powers the plane through the night.
The project's wide range of tech spinoffs comes from the range of corporate partners working with Solar Impulse, which includes a watchmaker, an elevator and escalator company, and several materials science institutes. Piccard and Borschberg strove "to think out of the certainties, to think out of the cabin" when building their plane, Piccard said.
That's why many of their innovations don't come from aviation companies, he said. "It was not the people who were selling candles that invented the light bulb," he said.
Coast to coast
The Solar Impulse team members also explained more on Tuesday about their plans for a U.S. flight next year, and for a round-the-world trip in 2015.
For their U.S. voyage, the team wants to start in San Francisco, end in New York and make several stops along the way, including one in Washington, D.C. They aren't sure yet what other cities they will visit, but will probably plan a route across the southwest because of low winds in the region, said Gregory Blatt, Solar Impulse's marketing director.
Solar Impulse hopes to raise awareness for the solar plane project in the U.S., perhaps by partnering with schools, Piccard said. For example, they could live stream a question-and-answer session between a classroom and a pilot who's in the air, Piccard said.
The team is also seeking additional U.S. corporate partners.
More tech for circumnavigation
For the circumnavigation trip, Solar Impulse will build another plane, the HB-SIB, which will have improved solar panels and batteries. That plane will also boast a longer wingspan than the HB-SIA's 208 feet (63.4 meters). The HB-SIB will need to support a larger cabin, which can carry more food and allow pilots to recline for short naps.
The team also wants to make a machine that uses solar power to isolate oxygen out of the air and pump it into the cockpit for the pilots. But the team isn't sure yet if that is possible, Blatt said. If they're successful, the pilots won't have to wear oxygen masks, as they do now in the HB-SIA.
Corrected Dec. 12: The story originally attributed a comment on carbon fiber sheets to Kat Hoffman. The information actually came from Alexandra Gindroz, a Solar Impulse spokesperson.