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Battery-powered aircraft creates aviation and technology history “Powered” Flight! T wo days before Christmas, a light aircraft took off from the Aspres sur Brec airfield near Gap in the French High Alps and flew for more than 50km without using a drop of petrol or avgas. It was the first flight of a fixed-wing, piloted plane powered only by battery and electric motor. The plane, named the “Electra”, was a single-seater Souricette woodand-fabric aircraft, built from a kit and modified for the purpose. It was fitted with a British-made 25hp electric motor (of the type used in golf carts) and 48kg of lithiumpolymer batteries. With test pilot Christian Vandamme at the controls, it flew a course through The Alps for 48 minutes. While electric-powered flight has been achieved before, it was either with ultralights, powered hang gliders or pilotless drones. In fact, SILICON CHIP featured such a flight more than fifteen years ago – in the October 1991 issue. And US inventor Paul MacCready, who developed the first man-powered plane, the Gossamer Albatross, has also pioneered electric-motor-powered microlights and ultralights, including a flight over the English Channel in 1981. However, a fixed-wing, conventional plane (one with an airworthiness cerby ROSS tificate) flying with only battery power 82  Silicon Chip has until now been a dream. A group founded to promote electric/green flight, the French “APAME” group, (rough translation Association for Promotion of Electric Aircraft), was behind the project, in collaboration with ACV Aero Services, Pegase, Capenergies and Onera. President of APAME, Anne Levrand, said that the flight showed that non-polluting, quiet, light aviation was within reach. “Fuel cost per hour of the Electravia was around one Euro, compared with about 60 Euro for an equivalent petrol-driven aircraft,” she said. “The motor and batteries will cost between ten and fifteen thousand Euro, roughly the same as current small petrol engines.” However, this comparison has started fierce debate amongst green and aviation groups, who maintain that when you take the cost and environmental impact of the batteries into account (especially the lithium) and then look at factors such as performance, petrol still wins hands-down. The debate highlights one of the major hurdles in electricpowered anything – but most importantly aircraft – the weight and weight-to-power ratio of the batteries. Typically, batteries produce just 2% of the energy of the same mass TESTER of petrol. siliconchip.com.au Some technical data: Aircraft: “ELECTRA” registration no F-WMDJ : One-seater Kit construction, in wood and fabrics Wing span : 9m Length : 7m Weight of the aircraft without batteries: 134kg Maximum weight for take off : 265kg Cruise speed : 90km/h Special ground-adjustable propeller from ARPLAST Electrical: Motor: 18kW disk brush type Batteries: Lithium - Polymer Total weight of batteries: 47kg Quick charge: 45 minutes And while huge reseach budgets in the battery field are currently producing exciting results (see the feature in the next issue of SILICON CHIP), they are still a long way behind the internal combustion engine. Moreover, with current and even foreseeable technology, battery power can only result in propeller-driven aircraft with all their current disadvantages over jet aircraft. But this flight demonstrates that electric flight is possible. The Times of London reported that Sonex, a leading US manufacturer of kit aircraft, is about to fly a 50hp electric plane that can carry two people at 220km/h for up to an hour before recharge. This puts the aircraft right into the recreational pilot market where modest-performing, light sport aircraft are in demand. The Times also reported that NASA and Boeing are currently researching hydrogen-fed fuel cells which will drive high performance and high power electric motors, capable of powering much larger aircraft for much longer SC flights. Earlier successes... Electric Ultralight Trike On August 25th 2007, the ultralight trike called “Electron Libre” (it means “free electron”!), powered by a 20hp electric brush motor and supported by APAME and ACV Aéro Service, performed a 22 minute flight in calm atmosphere conditions from Aspres sur Buëch airfield (Alpen). New powerful LIPO batteries allow such a performance. Of course the trike is almost noiseless. Flight with electric motor is now possible and affordable by all. siliconchip.com.au March 2008  83