A Fuel-less Flight Around the World: Making the Case for Solar

If someone told you that you could complete a round-the-world flight - 35,000km - without consuming a drop of fuel you might think they were making it up, or pulling from a Jules Verne story. But that’s exactly what Solar Impulse is doing – right now.

You may have heard about this special aircraft on the news, on social media, or even from a friend or family member. But what is Solar Impulse? And what exactly is the big deal about it?

Solar Impulse is a long-range, experimental aircraft that runs exclusively on solar power – takeoff and landing gear, powerful headlights, and communications equipment. The Solar Impulse project, created by Switzerland’s Bertrand Piccard and Andre Borschberg, intends to achieve the first round-the-world trip of Earth by a piloted, fixed-wing aircraft (i.e. air plane) using only energy from the sun! That means no fuel and no emissions for or from this revolutionary aircraft.

Sound cool? That’s because it is! Pilot Andre Borschberg already holds a world record for the longest solo flight: 5 days and 5 nights flying over the Pacific Ocean without fuel from Japan to Hawaii. Now the team is taking aim at the next record – the first solo trip around the world by a solar powered airplane. In March of 2015, Solar Impulse took off from Abu Dhabi. After some setbacks upon arrival in Hawaii, the aircraft today continues its journey across the United States, heading back to Abu Dhabi - the long way round.

Solar Impulse is able to take such long trips because of its design and use of solar energy technology. The plane itself has a wingspan of 72m – that’s wider than a Boeing 747! However it’s ultra-light cockpit only weighs 2.3 tons – the approximate weight of a family car. While the aircraft itself is quite large, it doesn’t weigh a lot in comparison. During flight, the only added weight is that of the pilot, and the diet he needs to survive.

Technically, Solar Impulse is the second of its kind - the first Solar Impulse prototype started flying in 2009 and was designed to handle trips up to 36 hours in length. As it has proven with record breaking flights, the current version of Solar Impulse is made of tougher stuff.

The plane and its wings capture the sun’s rays using solar cells that cover the top and wings - 17,248 of them to be exact. Each cell is just about the thickness of a human hair - approximately 135 microns thick. During the day, Solar Impulse gains up to 8,500m altitude and recharges each of the four lithium polymer batteries located on the undersides of its wings. The batteries power the electric motors that cause the plane’s four propellers to turn. Each blade is 4m long! At night the plane glides, relying on the energy that it gathered and stored during the day to power it through the darkness. This enables it to fly continuously day and night at an average airspeed of 75 km/h. Solar Impulse allows you to track all of those data in real time in their Virtual Cockpit (active when it is in flight)!

Solar Impulse creators and pilots Piccard and Borschberg are made of tough stuff, too. When the aircraft is flying at maximum altitude, temperatures outside of the cockpit can reach down to -40℃. A high-density foam insulation protects them from the outside, but temperatures inside the cockpit can still be a chilly -20℃. What’s more, pilots are only able to grab small naps of up to 20 minutes at any one time. The cockpit is a cozy 3.83m3 so there’s no standing room either. Why would they do something like this?

The minds behind Solar Impulse

The Solar Impulse project is an interdisciplinary effort that was born when Swiss psychiatrist and aeronaut Bertrand Piccard had a vision. He believes that clean technology and energies can reduce greenhouse gas emissions, cut energy consumption and conserve our natural resources. He teamed up with the former jet pilot, engineer and businessman Andre Borschberg to make that vision a reality.

The reason? They want to spread the word about the opportunities and possibilities of solar and other forms of green, renewable energy. The Solar Impulse team estimates that the craft has produced 5644kWh of energy so far on its flight path from Abu Dhabi to Hawaii - each kilowatt hour completely emission free! Imagine what this type of technology could do on the ground.