Your questions answered: solar-powered flight

Having already demonstrated the ability to fly non-stop for 24 hours in their first solar plane, the pair has now unveiled a second, more efficient single-seater craft that will enable them to take turns flying for up to five consecutive days and nights at a time — including flights over the Atlantic and Pacific oceans.

We put your questions about the engineering challenge of building such a craft, the personal challenge of flying it and the wider impact of the project to the two solar aviators and their support team.

What were the biggest changes between the new Solar Impulse craft and the original plane?

André Borschberg: First, we improved performance in order to reduce our energy consumption and have more reserves. Then, we modified the cockpit to improve ergonomics. In addition, we needed a more reliable aircraft with redundant safety systems and leak-proof electrical circuits in order to fly in humid conditions. Finally, we have a form of autopilot, that we call a Stability Augmentation System (SAS), which will maintain flight altitude and a directional heading so that the pilot will be allowed to rest.