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Air travel switches to electricity
Read Charles Bremner's Paris blog
The dream of inexpensive, ecofriendly aviation has come closer to reality after a French test pilot achieved the first flight in a conventional light aircraft powered by an electric motor.
The Electra, a wood-and-fabric single-seater, flew for 48 minutes for 50km (30 miles) around the southern Alps, winning a global race to apply battery power to a fixed-wing standard aircraft.
The APAME group, founded to develop green aviation, said that the flight showed that nonpolluting, quiet light aviation was within reach.
“This will be a real aeroplane that will have an airworthiness certificate,” Anne Lavrand, president of APAME, said. “It is a machine built for anyone with a pilot’s licence.”
The quest to replace noisy, fossil-fuelled aircraft engines with quiet, clean power has been under way for nearly 30 years. The big hurdle is the punitive weight of batteries, which produce only 2 per cent of the energy from the same mass of petrol.
Paul MacCready, a celebrated Californian engineer, pioneered exotic solar-powered flying machines, one of which flew from Paris to Kent in 1981. Recent advances in battery technology have led to electric power for small unmanned observation drones and radio-controlled model aircraft as well as the extra drive for motor gliders. Last summer the French group and a US inventor each flew electric-powered, delta-winged microlight aircraft for the first time.
The last challenge has been to scale up electric drive to equip passenger-carrying conventional aircraft of the kind flown by recreational pilots. Ms Lavrand’s group, financed by French aerospace companies and other donors, started its project quietly 18 months ago. “When we began, no one believed we could do it,” she told The Times from APAME’s base, near the southern Alpine town of Gap.
The group used a Souricette kit aircraft and adapted to it a 25-horsepower British-made motor of a type that powers golf carts. The key to their pioneering flight on December 23 was the new generation of light lithium-polymer batteries, 48kg (105lb) of which supply power in the Electra, which has a 9m (30ft) wingspan.
A new category of modest-performing, light sport aircraft is ideally suited to the new battery power. Many recreational pilots will be prepared to forgo speed and range if they can escape the cost, noise and guilt of carbon-belching, gas-guzzling petrol engines, the firms say. Sonex, a leading American manufacturer of kit aircraft, is about to fly a 50-horsepower electric motor that will carry two people at 220km/h (135mph) for up to an hour before it has to be recharged.
Ms Lavrand said that the fuel cost per hour of the Electra was €1 (70p) compared with about €60 for an equivalent petrol-driven machine. The motor and batteries will cost between €10,000 and €15,000, about the same as existing small petrol engines.
“It’s expensive, but you have to think of it like buying the fuel up front,” Ms Lavrand said.
Electric power for larger aircraft, including airliners, is also on the horizon, with research by Nasa and Boeing into the holy grail of the field: hydrogen-fed fuel cells. These will drive electric motors with power like those on French high-speed trains.
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