Science & technology | Aviation

Volting ambition

Battery-powered planes are getting ready for take-off

ELECTRIC aeroplanes have been busy breaking records. On July 10th Airbus’s E-Fan, piloted by Didier Esteyne, became the first twin-engined all-electric aircraft to cross the English Channel. At least, that is the firm’s version of events—for about 12 hours earlier, Hugues Duval, another Frenchman, had made a round trip from Calais in his twin-engined Cri-Cri electric plane. Airbus discounts Mr Duval’s flight on the grounds that he was towed aloft by a conventional plane. Meanwhile, Pipistrel, a Slovenian producer, was prevented from turning up to show off its single-engined electric trainer because Siemens, which supplied the motor, refused permission for it to be used over water.

The first person to cross the Channel in any sort of electric plane was Paul MacCready, an American aeronautical engineer, who made the journey in the flimsy Solar Challenger in 1981. Although this aircraft used an electric motor to drive a propeller, it did not have a battery, for it obtained its power directly from solar cells. Another solar aircraft (this time equipped with batteries, to store surplus power) is now being flown around the world by a Swiss team. But after a record-breaking five days and nights in the air crossing the Pacific from Japan, Solar Impulse 2 is stuck in Hawaii because its batteries overheated.

The E-Fan (see picture) is a two-seater made from carbon-fibre composites and powered by two 32kW electric motors that drive ducted fans attached to the fuselage. The motors draw their power from a lithium-ion battery pack, similar to those used in electric cars. The plane is designed to fly for up to an hour, though it has a backup battery holding an extra 30 minutes-worth of juice in case of emergencies.

Electric propulsion is already used by drones, but, as these ventures show, there is now interest in employing it for manned aircraft as well. Airbus is equipping a factory in France to make E-Fans. The firm plans to sell them as low-cost training aircraft for pilots in the making.

E-Fans are mechanically simpler than combustion-engined aircraft, so running and maintenance costs should be lower. Moreover, they are much quieter, so would be less annoying for an airfield’s neighbours—especially as student pilots do lots of circuits. But Airbus sees the E-Fan as just the start. Battery technology is improving all the time. Airbus, and other firms, are looking at electrically powered and hybrid airliners with up to 20 seats.

As existing electric cars attest, today’s lithium-ion batteries are limited in range and can prove temperamental—not least by demonstrating a disturbing tendency to burst into flames if overheated. That explosive fate was avoided by Solar Impulse 2, though excessive insulation caused the temperature in parts of its batteries to spike enough to create permanent damage. The team said this week that repairs and modifications mean the aircraft will remain in Hawaii until early in the spring of 2016. Bertrand Piccard and André Borschberg, the two pilots who are taking it in turns to fly the single-seater plane, will then be able to continue their journey on to America and eventually back, via Europe, to Abu Dhabi, whence they took off in March.

This article appeared in the Science & technology section of the print edition under the headline "Volting ambition"

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From the July 18th 2015 edition

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