Total Electrical
By Peter Garrison
August 2008
 Hangar wits at a loss for an original joke sometimes fall back on the time-tested quip that a liquid-cooled airplane makes as much sense as an air-cooled submarine. When several of them (wits, not submarines) are present, the observation that the problem with electric airplanes is that the extension cord gets twisted cannot be far behind.
Nevertheless, in April I attended a day-long symposium on electric airplanes in San Francisco. It was the second annual meeting of its kind -- I missed the first -- put on by the CAFE Foundation, which does a lot of good work, some of it in collaboration with NASA, investigating ways to improve the efficiency of personal aircraft.
Like a movie that begins with an establishing shot of the earth seen from outer space, the presentations opened with one on global warming. Why global warming? Because it raises the most fundamental reason for interest in electric aircraft, namely the sinking repute of fossil fuels. That global warming was the introductory topic hinted, moreover, at what was to become more and more apparent as the day went on: that the subject of electric airplanes was seen as having much wider ramifications than a simple need for efficient structural design and post-state-of-the-art motors and batteries.
(In the interest of balance I will digress briefly to mention that one far-seeing aviation figure, not present at this symposium, has declared himself to be in favor of human-caused global warming because it will help to forestall "the coming ice age.")
A former confederate of the late Paul MacCready next traced the history of electric flight back through the man-powered "Gossamer" series, one of which was equipped, and flown, with an electric motor. MacCready's efforts culminated a year later in what remains the most impressive accomplishment of a manned electric airplane: a 163-mile Paris to London flight, in 1981, powered solely by sunlight.
Some speakers went on to deal with topics specifically germane to practical electric flight: the power-to-weight ratio of motors and batteries, design of appropriately efficient airframes, the comparative merits of different kinds of power trains and energy storage media, and various electric airplanes -- some of them commercial products -- that already exist. Others discussed more tangential subjects, such as the definition of approach paths optimized for fuel saving and the prospects of the airplane -- some airplane, not necessarily an electric one -- as a "daily driver" commuter vehicle.
 As far as the underlying science and technology are concerned, it's pretty well established that at least certain types of electric airplanes are not only feasible but even quite practical. At least one, the German Antares 20E, is already on the market, and a second, the side-by-side two-seat Pipistrel Taurus Electro, made in Slovenia (within yodeling range of Austria and Italy, if your geography momentarily fails you), is due at the end of this year. Both are self-launching sailplanes whose pylon-mounted engines and propellers retract fully into the aft fuselage. The cost of climbing to 6,000 feet under electric power, a Pipistrel engineer reported, is one-sixth that of climbing to the same altitude in the Rotax 503-powered version of the Taurus. Boeing recently demonstrated an electric two-seater, but this seems to be a research project aimed at developing more efficient APUs and garnering a little publicity in the process; Boeing is not going into the LSA business. John Monett, the developer of the popular Sonex homebuilt kit, unveiled an electric version of his 1,100-pound single-seat Waiex at Oshkosh in 2007; as far as I know, it has not yet flown. A number of solar-powered airplanes have been built with the eventual aim of achieving "eternal" flight, and durations of more than two days have already been demonstrated, proving, if it needed to be proved, that enough extra energy can be collected by solar cells during the day to last an airplane through the night. A European project, Solar Impulse, is currently developing an airplane that will do Voyager and GlobalFlyer (but not the Breitling Orbiter 3 balloon) one better by circling the earth nonstop with no fuel at all.
As anyone who owns a flashlight knows, the capabilities of the Energizer Bunny are greatly exaggerated. That's the problem with electric cars and electric airplanes as well. The power is there, but the range isn't. The self-launching sailplane is therefore a natural first application for an electric powerplant: It requires only a brief expenditure of stored power, and can then remain aloft as long, and fly as far, as conditions permit. In 1990, Sunseeker, a sailplane built by Eric Raymond with the upper surfaces of its wings entirely covered with solar cells that charged storage batteries, made a transcontinental flight -- well, a series of flights -- by a combination of electric self-launch and cross-country soaring. It's not likely, however, that Raymond kept many appointments along the way.
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