The Solar Impulse could be the plane of the future; powered purely by the sun’s energy, the machine, developed by a cadre of corporate partners (and two determined pilots) has completed several long-flight tests proving its technology.
Imagine flying up the coast, the sun glistening on the deep blue ocean far below, and hearing…nothing. Instead of a jet-engine roar, you discern just the wind whistling by. The Solar Impulse plane gives just that experience for its pilot; like an almost-silent electric car, this plane runs on the power of the sun, no dirty fossil fuels required. It can fly for 26 straight hours (yes, even at night!) and just this week completed its first-ever flight across the United States, touching down at New York City’s JFK airport.
Ten years ago, Bertrand Piccard and Andre Borschberg launched a daunting project: to build a plane that would run on the power of the sun alone. Meant to carry a message about sustainability, challenge the orthodoxy of flying, and bring together technology and sustainability (not to mention some serious engineering) success has come with the vision of a few and the sweat of many.
The project cost over the past decade is, according to Piccard, “About half the cost of a Hollywood blockbuster movie,” a detail that’s both accurate (they’ve spent about $150 million so far) and a comment on what current society finds valuable enough to invest in. It’s also, all things considered, pretty cheap as far as world-changing experiments go.
So how does the plane actually work? Flying during the day when it’s sunny is simple; the plane’s giant wings (about the size of a 747 to carry the weight of a 3,500-pound plane body) are covered in solar panels; enough to get the electric engines up and running for takeoff. The plane is so light that it alights with just 500 feet of runway. And no matter how overcast the day, once it reaches 30,000 feet, above cloud cover, there’s solar power galore. While flying during the day, the plane continues to gather energy and store it in batteries; as the day fades, gliding comes into play. It takes about four hours to glide down to 5,00o feet, using no power (gravity is free). Then the plane can run on the stored solar energy in its batteries. Piccard explains, “There are two ways to store energy: there’s potential energy we can harvest at altitude and the other is chemical storage. Together, that gives us 12 hours of flying time, enough so you can fly through the night.” By the time you need more solar energy, the sun is rising. The Solar Impulse team has proven this experiment by flying for 26 straight hours.
One thing that’s not sustainable about this plane? “The pilot,” says Borschberg. “A person can fly a maximum of about 26 hours; but the plane is almost limitless,” he says, since it doesn’t have to stop to refuel (unlike a human being, who needs to rest, as well as eat—oh biology).
Putting together such a lightweight plane was a task that required all 79 corporate partners to dig deep into their R&D departments. Note that they aren’t sponsors; the companies identified on the plane, including Bayer, Swiss Re, Omega, and Schindler all contributed newly developed materials as well as cash. Since even regular glue was too heavy, Bayer MaterialScience developed one that has carbon tubes of nanofiber, and since temps at 30K feet are consistently -40C, extremely light insulating materials were developed (which will now be used in refrigerators and other more terrestrial applications). Due to the high degree of engineering (this is a Swiss project after all), the plane runs at 94 percent efficiency.
Next for the project is a second plane (this one will have a bathroom!) and be able to carry 3-4 people. When asked about the project’s next iteration Piccard said, “We’re going around the world; 500 hours of flying in April and June of 2015. [Let's] get rid of limits and fly forever.”
Main Image courtesy Solar Impulse.