Solar Impulse 2 - Plane that needs no fuel

Everything you need to know about Solar Impulse 2 

Illustration: HERI IRAWAN

The Red Bulletin talks to the men behind Solar Impulse 2 to find out their motivation behind the project, and how it can fly around the world on zero litres

In 1999, explorer Piccard made the first non-stop around-the-world balloon flight.

“Every day I was afraid of running out of gas. We landed with almost nothing left,” he says. “I thought, ‘Now I have to do another flight, but with no fuel.’

Teaming up with engineer and pilot Borschberg, they built Solar Impulse 2 – a plane that this July completed a 40,000km circumnavigation of the globe powered by nothing but sunshine. 


  • The cockpit has room for one pilot
  • The toilets are in the seat, which reclines flat
  • The cockpit is also where you heat up your food and change clothing
  • In daylight, the plane ascends to 9,000m to charge its solar cells
  • At night, it uses stored battery power to maintain altitude
  • The wingspan is bigger than a 747 and it’s extremely light –the weight of a car
André Borschberg, 63, and Bertrand Piccard, 58

The ideas Men

André Borschberg, 63, and Bertrand Piccard, 58

© Solar Impulse | Ackermann | Rezo  

THE RED BULLETIN: How hard is it to build a solar-powered plane?

ANDRÉ BORSCHBERG: When we proposed it to the aviation industry, they told us it was impossible.

BERTRAND PICCARD: Nobody in the aviation world could build the carbon-fibre pieces for Solar Impulse – so light and big – so we went to a shipyard, to the people who build the Alinghi catamarans for the America’s Cup. These guys have no idea how to build an aeroplane, but they know carbon fibre. By putting together our engineers and this company, we got new materials and ways of construction.

“The plane has been designed to be extremely energy efficient. The wingspan is bigger than a 747 and it’s extremely light – the weight of a car”
Comparison between the Solar Impulse 2 and the Boeing 747-8I

A comparison: Solar Impulse 2 (72m), Boeing 747-8I (68.5m)

How close were you to a dead battery each sunrise?

AB: In good weather, air goes down and it’s easy to fall 2-3cm a second, which for us is 10 per cent of performance. By sunrise we’d only have 10 per cent battery left, so we’d be really close to the limit. When we reached the Pacific, we hadn’t flown an entire cycle and now I was going to be in the plane for five days and nights.

After two months in Japan, I saw the weather improving and took off, but the equipment that monitors the plane as I sleep stopped functioning. The engineers called me back, but I decided otherwise, because the weather is critical. They were threatening to resign because they didn’t understand the risk I was taking. It created a lot of emotion in the mission.

„The solar airplane has now successfully made it full circle around the world, proving that clean technologies can really achieve the impossible“

© youtube // SOLAR IMPULSE

So, could this plane fly non-stop around the globe?

AB: Theoretically yes, but practically it will be a hell of a challenge with existing technology. Firstly, there’s sustainability for the pilot. I flew five days, I could fly seven, but to fly 20 we’d need to rethink life in the cockpit; it’s not impossible. Also, each day we go up to 9,000m [to charge the solar panels] and each night we glide down, so we need weather that allows that. Over a quarter of the globe, it’s feasible; over the entire globe, it’s difficult.

Is that the ambition?

AB: First I’d like to build an unmanned version capable of flying above bad weather for six months, replacing or enhancing what satellites are doing in a more flexible, sustainable way. Bring the plane down, change equipment, send it back up. That’s something we’re working on.

BP: My goal is not to make a third flight around the world, but to leverage the success of Solar Impulse to promote clean technologies. I’ve been appointed goodwill ambassador for the United Nations and I’m working to shape the world’s energy policy. The limit is not technology, but people who are prisoners of old beliefs. We have to do something real for the world. 

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11 2016 The Red Bulletin

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