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Solar Impulse

As I write this, Solar Impulse is already in the air on the last 48-hour leg of its remarkable journey: the first round-the world flight by an aircraft that uses no fuel except sunlight. By the time you read it, pilot Bertrand Piccard will probably have landed in Abu Dhabi, to global acclaim. And you can’t help wondering: is this the future of flight?



“You can fly with no pollution and no noise, and land in urban airports, making no disturbance for the neighbours….And maybe sometime people will say this all started with a crazy idea of flying around the world in a solar aeroplane, and the outcome was useful for everyone.”

But Solar Impulse, with the wing-span of a jumbo jet, can carry just one person. Photoelectric cells on the wings power it during the day, and recharge the batteries that take it through the night (barely)– but its average speed is only 75 km/hr, and it took 17 flights and fifteen months to travel around the world, so we are still a long way from the Promised Land.

You can’t just scale Solar Impulse up and get an electric-powered commercial aircraft that carries 50 people, let alone the 500 passengers that they can jam into a long-haul 747 or A380. The basic problem is coming up with light-weight, high-capacity “traction” batteries – ones designed to provide the main power for large vehicles for a period of hours – and progress on this front has been very slow.






There is another potential environmental problem linked to fuel-burning aircraft, and that is the “contrails” (condensation trails) they often leave behind them. The contrails are formed by water vapour from the engine exhaust that freezes when the humidity is high and the air temperature is low, usually in the upper troposphere. They can last a long time and spread out until they turn into cirrus clouds covering large parts of the sky.


So congratulations to Bertrand Piccard and Solar Impulse’s other pilot, Andre Borschberg. Maybe we will have electric airliners one of these days, if only somebody can come up with the right battery – but in the meantime we should be working hard on making carbon-neutral fuel.
To shorten to 725 words, omit paragraphs 12 and 13. (“There is…altitude”)