Solar Impulse Crosses America

Who needs fuel when the sun can keep you aloft?

Solar Impulse over San Francisco. What it lacks in speed, it gains in energy-efficiency. (Solar Impulse/ J. Revillard)

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Did you ever sleep during any of your flights? If so, is there a place to rest inside the airplane?

Piccard: There’s no way to sleep, as we have no autopilot. But when you have the privilege of flying the most incredible airplane in the world, one that flies day and night with no fuel, the last of your wishes is to waste your time by sleeping. It’s also a big responsibility to carry the hope of so many thousands of people who have signed up on our website to support the introduction of clean technologies in our world.

Is pilot fatigue an issue during these long flights?

Borschberg: To fly the aircraft is so beautiful and special that you don’t feel the fatigue and want to take advantage of this fabulous moment. Our passion for the project and for flying certainly play an important role. Interestingly, we learn to focus and concentrate on the present moment instead of thinking how many hours remain until landing. We end up by creating our small world in the cockpit in which we feel very comfortable.

What food and beverages have you consumed in the air?

Piccard: Since I had to concentrate on the flying and not on eating, I had some energy food and beverages.

How long did it take you to learn to fly the single-seat Solar Impulse? Is there any aircraft type that you would compare it to in terms of flight characteristics?

Borschberg: I am a professional pilot who has flown many different aircraft since I was 17 years old, but I tell you, Solar Impulse is a special airplane. Its lightness and slowness make it very sensible to the slightest turbulence. It behaves like a large microlight, except that the disproportionate scale creates a lot of inertia. The reaction time for controls is therefore very long, with the risk of over-correcting and inducing oscillations. A former NASA chief pilot tried our simulator; he could not land the airplane. He crashed it on every landing and was furious.

Can Solar Impulse fly during cloudy weather? Or does the charging of the aircraft’s solar cells require full sun?

Borschberg: Dense clouds above the airplane will certainly reduce the amount of energy we can collect. This would not affect the day flight but could limit the possibility of flying through the following night. That’s the reason why we have a team of weather specialists on the ground, planning each flight very thoroughly in order to ensure the airplane is always flying in sunny weather, especially in the morning.

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