Solar Impulse HB-SIA / Solar Impulse 2 Family

Solar Impulse was a Swiss family of crewed experimental aircraft designed to fly on solar energy stored in onboard batteries. The first prototype proved day-and-night solar flight and intercontinental operation, while the larger Solar Impulse 2 was built for ocean crossings and a multi-stage circumnavigation. Their extreme wingspans, very low mass, and energy-management systems turned the aircraft into flying laboratories for efficient structures, electric propulsion, and renewable energy.