Solar-powered plane plans to circle the globe

On two wings and a prayer: Solar Impulse 2 is revealed to the world in a Swiss hanger.

Next year Solar Impulse 2, a single-seater aircraft powered only by the sun, will make its first round-the-world trip. Is this the start of a new green form of flying or is it just a stunt?

‘Theoretically it can fly forever,’ says one of the founders of the Swiss-based Solar Impulse project. Although it was not the first solar-powered plane, the Solar Impulse, which first flew in 2009, has certainly been the most successful. It has managed a series of impressive firsts and shown that a solar-powered plane with rechargeable batteries can fly all day and all night, travel between continents and, last year, fly from coast to coast across the United States.

This week an improved version, Solar Impulse 2, was unveiled with the plan of flying it around the globe next year. The single-seater aircraft weights 2.3 tons, as much as an average family car. It has a carbon-fibre wingspan of 72 metres, wider than that of a Boeing 747 jumbo jet, and its upper surface is covered with more than 17,000 solar cells which power the four electric motors and charge the batteries. It has a top speed of 87 mph and can cruise at 30,000 feet, the normal altitude for commercial aircraft.

The round-the-world trip will start next March and take 20 flying days, spread over several months. It will begin in the Persian Gulf, flying east over the Arabian Sea, India, Burma, China, the Pacific Ocean, the United States, the Atlantic Ocean and Southern Europe or North Africa before returning to its departure point.

To cross the Atlantic and Pacific, the plane will need to stay airborne for at least five days at a time, gaining altitude during the day when the sun is out and slowly descending to about 5,000 feet during the night. This will be testing for the pilot. One of them says, ‘We have a sustainable airplane in terms of energy. We need to develop a sustainable pilot now.’

Others say yes. Solar Impulse 2 is just the beginning, a test bed for the various technologies which will improve, become more robust and get cheaper. Modern aviation was only born in 1903 with the Wright Brothers’ first powered flight and has progressed since then at amazing speed. In 1927, for example, Charles Lindbergh became an overnight global celebrity for his daring solo non-stop flight across the Atlantic. Yet within 12 years airlines were making regular transatlantic flights.

Flying to nowhere?

It is obviously a great adventure, but does this project really have the potential to change the face of flying?

Critics say no, this is not the future of aviation. These aircraft may not burn any fossil fuels, but they are very expensive, slow, fragile and incapable of flying under anything but ideal conditions. Every year the world’s airlines carry over 2.6 billion passengers and 48 million tons of freight. Could even a small part of that ever be done by solar-powered aircraft?

You Decide

  1. Are solar-powered aircraft the future of flying?
  2. Would you pay more to fly in an aircraft that didn’t contribute to global warming through its emissions?


  1. Create a poster showing different types of aircraft from the earliest days of flight to the present.
  2. Modern aviation has progressed through invention and innovation. Research online and try and find five important advances.

Some People Say...

“Aviation is proof that, given the will, we can achieve the impossible.’Eddie Rickenbacker”

What do you think?

Q & A

Why would we ever need solar-powered aircraft?
Fossil fuels won’t last forever. At some point they will run out or else become prohibitively expensive. It is therefore important to investigate any alternative means of sustaining such a vital part of modern civilization as air travel.
I’m never going to want to catch a plane with a top speed of 87 miles per hour.
Projects like Solar Impulse are there to work out all the problems involved with new technology and find ways of improving it. Once that is done, commercial versions can be produced and they are improved on in their turn. You wouldn’t be happy today with a mobile phone from 20 years ago, but without that version and others like it, there wouldn’t be the modern ones we have now.

Word Watch

This is a short name for carbon-fibre-reinforced polymer, a type of plastic. Though relatively expensive it is often used to make aircraft and racing cars, where both strength and lightness are very important.
Solar cells
They are also called photovoltaic cells and are devices that convert the energy of light directly into electricity. The first practical ones were built around 50 years ago, although it is only in the last few years that they have become cheap enough to be commonly used in our houses.
Fossil fuels
These are substances like coal, oil and natural gas which are created from ancient fossilised plants and animals, buried for millions of years in the Earth’s crust. When they are burnt they release carbon into the atmosphere and contribute to global warming.


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