Perpetual Flight No Longer a Myth

On Tuesday we reported on an attempt to fly a plane for a full day without a drop of fuel. That attempt was a success – and the designers say they expect to one day fly a similar plane around the world.

As the name implies, the Solar Impulse project’s plane HB-SIA is powered entirely by the sun’s rays. Though it had flown before, this was the first time it had flown long enough that it needed to rely on storing solar energy to get through the night: the first time that’s ever been done by a solar plane.

The way the plane works, with four electrical engines and solar panels on the wings, is both remarkably simple in concept and extremely difficult in practice. As well as using a carbon fiber design to keep the weight low, the power of the plane is limited to around 6kW and the top speed is a mere 43 miles per hour.

The plane took off at 6.51 am local time in Switzerland yesterday morning, reached a top altitude of 28,000 feet, and touched down again at 9 am today. It still had three hours of battery life remaining, more than expected.

That the plane was able to fly all night means that theoretically it could stay airborne indefinitely, limited only by components wearing out. However, In practice, there are human limits as to how long a pilot could stay in the air.

The plan now is to produce a follow-up model next year which will add a pressurized cabin and extra oxygen supplies so that the plane can get as high as 39,000 feet. The necessary tweaks to the plane design will mean the wingspan will have to be brought up to 260 feet, slightly wider than that of the super-size Airbus A380 passenger airline.

In reply to the question of whether there’s any point producing such a plane for a single passenger (a two-seater model is in the works to allow for a non-stop circumnavigation of the globe), the designers noted that the now commonplace transatlantic flight began with single-seater planes.

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