With clouds overhead and predawn winds higher than expected, the Solar Impulse team remained in suspense for nearly an hour on April 21. Pilot and project co-founder Bertrand Piccard was strapped into the solar-powered airplane with the wingspan of a jetliner, and pushed into position by a small army of ground handlers. After months of delay to the round-the-world journey on zero fuel, the launch was at last at hand.
Lined up and waiting at 5:44 a.m. local time in Hawaii, the weather improved and Piccard was cleared to launch the planned 62-hour leg to California.
The planned flight was expected to be roughly half the duration of the record-breaking solar airplane’s longest leg to date, and followed months of delay to the circumnavigation. The aircraft’s battery system (by far the heaviest and arguably the most critical system on board) overheated between Japan and Hawaii in July. Repairs, upgrades, and fundraising culminated with test flights in March, and the $170 million mission to promote renewable energy was at last ready to resume.
“OK, let’s go,” Piccard said over the radio at 6:15 a.m. Hawaii time. The motors began to turn and within seconds the gossamer aircraft floated skyward to cheers from mission control and salutes from the ground.
“And don’t forget to come down,” Piccard was reminded as he climbed out.
The initial phase of the flight appeared to go smoothly despite a few encroaching clouds, and Piccard was able to reduce power quickly to save energy during the climb. Viewers around the world can follow the mission online through a feed that carries live video and aircraft telemetry as Piccard makes his way to Mountain View’s Moffett Airfield, where the original Solar Impulse prototype landed in 2013.