After a one-and-a-half hour delay, the decision was finally made that the Swiss experimental plane Solar Impulse 2 would not take off from Nagoya, Japan for Hawaii due to weather problems.
The big question was would the solar-powered plane be able to make it through heavy cloud cover that came up, and it couldn’t take off later during daylight hours due to high winds.
The solar-powered plane was originally scheduled to take off at 7:30 a.m. HST. It will now go back into its mobile hangar at Nagoya’s Komaki airport as the mission control crew in Monaco will decide when the next best window of flight will be available.
This leg of the plane’s worldwide flight is the most challenging, as Solar Impulse 2 would have to fly for at least five consecutive days and nights across the Pacific with no stops along the way.
Earlier, Swiss pilot and project co-founder Andre Borschberg, sat in the plane’s cockpit, looking patient but serious.
Borschberg landed in central Japan on June 1 while en route from the Chinese city of Nanjing to Honolulu. He was to fly the plane solo during the roughly five-day trip, taking short naps, doing yoga and meditating to endure the lack of sleep.
The airplane carries no fuel, so project engineers are using simulations to determine when it is safe to fly. The first Pacific leg is the riskiest because there is no place to land.
Borschberg had been waiting for a weather front stretching from Alaska to Taiwan to clear enough for him to resume the 8,175 kilometer (5,079 miles) journey across the western Pacific, the longest leg of the round-the-world journey which began in Abu Dhabi.
The length of the journey means that the weather forecasts the project’s simulators use to decide if it is safe to embark are at their limits of reliability, he said.
“We don’t want to take too much of a risk,” he told reporters earlier in Tokyo. “Either the airplane is still flying and it gets to where it is going, or it’s in the water and it’s a failure. It’s either 100 percent or 0 percent. There is no 50 percent. That is why we are so careful.”
The project’s leader and co-founder, Bertrand Piccard, was to guide Borschberg from a control center in Monaco. They are taking turns flying the plane solo.
The Solar Impulse 2 is powered by more than 17,000 solar cells on its wings that recharge its batteries, enabling it to fly. But bad weather and nights are challenges because diverting around clouds takes extra energy, and the aircraft is not designed to withstand rain, turbulence and heavy winds.
The aircraft travels at about the same speeds as a vehicle. At night, it descends from its maximum altitude of 8,500 meters (27,887 feet) to 3,000 meters (9,850 feet) to minimize power consumption as it draws from its batteries.
In the morning, the plane resumes producing power, but it needs to have enough left-over power to ascend to the daytime altitude.
The Solar Impulse project is meant to demonstrate the potential of improved energy efficiency and clean power, though solar-powered air travel is not yet commercially practical, given the slow travel time, weather and weight constraints of the aircraft.