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Electric airplanes? EAS guides the way

The first-ever CAFE Foundation Electric Aircraft Symposium (EAS) in 2007 attracted only two attendees not on staff at the foundation, and one of them, Steven W. Ells, was not overly impressed. Ells returned in 2013 for the seventh symposium and found a different story.

Although there were a few electric airplanes flying before the first Electric Aircraft Symposium in 2007, EAS (with some financial stimulus from Google) has been a powerful catalyst for expanding the world of electric aircraft.

Brien SeeleyBrien Seeley, president of the Comparative Aircraft Flight Evaluation (CAFE), and the members of the CAFE Foundation board have grown the symposium into a meeting of some of the best minds in the country.

The Electric Aircraft Symposium VII, April 26 and 27 in Santa Rosa, Calif., featured 25 speakers on topics ranging from a propeller safety device to sustainability and maintenance. Brien Seeley, President of the Comparative Aircraft Flight Evaluation (CAFE), and the members of the CAFE Foundation board have grown the symposium into a meeting of some of the best minds in the country.

Each presentation at the symposium was very thought-provoking, especially related to energy conservation and future flight. The internal combustion engine is only about 35-percent effective at converting energy to work; electric motors easily top 90 percent. Since powerful electric motors are very light (50 to 70 pounds) judged against a comparable internal combustion engine (300-plus pounds), the electric motor provides airframe designers with much more freedom to create designs to optimize thrust using large-diameter slow-turning propellers. Electric motors are quiet and smooth, have few moving parts, and require very little maintenance.

Experts such as the Thomas and Christopher Cook of LithiumStart, Winfried Wilcke of IBM Research, and Eric Darcy of NASA-JSC spoke about batteries and battery safety devices.

Power, measured in watts or horsepower, is the output of an engine or motor. Electrical energy is measured in watt hours; a watt hour is one watt expended over one hour. Batteries simply don’t yet provide enough energy per pound, especially when compared with avgas. To compete successfully a battery must be capable of producing a great deal of energy (watts) for a good length of time (hours) per pound (or kilogram).
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