Tuesday, July 5, 2011
Light-Sport Chronicles: Profiles In Vision, Randall Fishman
This “garage” builder of electric aircraft wants to quietly change the world
Flash-forward: What is electric flight's Steve Wozniak up to these days? Fishman hopes to have ElectraFlyer X, a lightweight, two-seat composite/carbon-fiber motorglider in development for three years, ready for Oshkosh. He's also testing his own electric motor and controller designs, and prototyping an electric ultralight. Meanwhile, his Trikes are available for purchase.
"The recession has made this not a great business right now," admits Fishman. "I've done okay because I've kept it small, selling a few complete trikes and many propulsion kits, meters and electronic controllers for people to modify their own ultralights."
The X model is, for now, intended as an experimental homebuilt kit to be flown as a light-sport aircraft. "Once FAA gives us the okay for electric propulsion, we'd like to sell it as a turnkey S-LSA aircraft."
His take on competing electric projects? A few well-funded efforts (which shall remain nameless) appear to be too heavy and inefficient aerodynamically to be workable. He believes the key to success—electric aircraft that can be produced and flown right now, not five years down the road—lies in maximizing the technology we already have.
The key to success—electric aircraft that can be flown right now—lies in maximizing the technologyA fully charged battery is equivalent to a tank of gas. Energywise, it takes around 72 pounds of fully charged batteries to equal the energy potential of one pound of gasoline. When you factor in the efficiency of an electric motor, about 90% compared to the best gasoline engine efficiency of 23-25%, the ratio narrows, but it's still around 20:1 in favor of gasoline power.
we already have.
we already have.
Batteries remain the performance technology bottleneck that electric scientists and engineers are working on. That dictates light, very efficient airframes to maximize the electric power we currently have.
"If we got a tenfold increase in the specific energy density of batteries," says Fishman, "then we could do lots of things modern airplanes do in terms of performance." Today, practical electric airplanes need to follow a simple equation: Multiplying weight times sink rate tells a designer how much raw power is needed to keep the airplane up.
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