Strange as it may sound, a solar-powered plane had flown over half the Pacific Ocean before a battery-powered one crossed the English Channel for the first time, and it’s already sustained enough damage to require serious repair.
The Solar Impulse 2, an aircraft that runs completely on solar power, landed in Hawaii on July 3, five days after its departure from Japan—setting a record, at 4,000 miles, for the longest distance traveled by a solar-powered aircraft without stopping. It accomplished the feat a full week before the first battery-powered plane flew across the 30-milewide body of water between England and France.
The aircraft will undergo extensive repair in Hawaii, delaying its planned aerial circumnavigation of the globe, after it was discovered that the plane’s batteries had overheated during the flight.
“The damage to certain parts of the batteries is irreversible and will require repairs and replacements that will take several weeks to work through,” the Solar Impulse team said in a statement.
Overheating is a perennial problem among electric-powered devices, as anyone who has driven a Tesla, or just owns an old laptop, may be familiar with.
To capitalize on the limited hours of sunlight, the Impulse flew as high as 28,000 feet above sea level during daytime, before descending to 5,000 feet above sea level at night. The team did not say if the overheating was a result of the plane soaring, like Icarus, too close to the sun.
Despite the groundbreaking nature of the flight, the Impulse is only a proof-of-concept that solar planes can be built and flown. The extreme dimensions of the aircraft—its 236-foot-long wingspan is almost 40 feet wider than a Boeing 747’s, but only able to carry one person—makes it impractical even as a personal, much less commercial, form of transportation.
With regard to weight, the respective crafts are even more lopsided in comparison. With almost a quarter of its weight coming from its batteries, the Impulse scales in at an airy 5,000 pounds, which is only around 1/200th the weight of the Boeing 747.
A solar-powered aircraft’s ability to be its own source of power makes it conducive toward flights of great—and even indefinite—lengths. From 1994 to 2003, under the Environmental Research Aircraft and Sensor Technology (ERAST) project, NASA experimented with a remotely piloted solar-powered aircraft that could fly almost up to 100,000 feet, with the eventual goal of using it as a satellite, monitoring everything from storms and agriculture to decaying pipelines. The Helios Prototype was the fourth and final aircraft developed under this project.
The ERAST project came to an end in 2003, when the Helios Prototype crashed into a Hawaiian island, irreversibly damaging its fuel-cell engine. NASA had originally wanted to develop an aircraft that could fly for up to 6 months at a time.
NASA appears to have abandoned its solar-powered aircraft ventures for now, instead focusing on battery-powered ones, testing planes with as many as 18 propellers.
The Impulse began its journey around the globe in March 2015 in Abu Dhabi, United Arab Emirates, and will head to Phoenix, Arizona, once its batteries are repaired.