February 2013

Experimenter is a magazine created by EAA for people who build airplanes. We will report on amateur-built aircraft as well as ultralights and other light aircraft.

Issue link: https://experimenter.epubxp.com/i/108002

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Page 18 of 44

respectable soaring performance ("…with an honest 22-to-1 glide ratio and 1.2 meters/second (236 feet/minute) sink rate," said Fishman). It comes with Fishman's personally specced and tested motor, motor controller electronics, and LiPo battery packs. Fishman is a one-man operation, a kind of electric flight general contractor. His creations live in a flux of constant refinement and innovation as he works closely with airframe and electric power designers, funds the research and development phase, tests prototypes, then has the components professionally produced. Still, his shirt-sleeve approach has kept him in the forefront of an often well-funded field with many exotic prototypes, but precious few production aircraft. Electric flight remains a Wright/Curtiss/Bleriot experience for now. The ULS airframe, manufactured under contract overseas in Europe, arrives at Fishman's hangar in Sebastian, Florida, for final assembly, rigging, avionics install, and test flying. Power comes from his own third-generation, 20-hp "outrunner" brushless motor, similar in concept to what you find in remote-controlled models. Outrunners feature a ring of magnets fixed to the inside of an outer shell that rotates around coils of copper windings. "I know what I want," he said about electrifying airframes. "I give the motor designer the power output, torque and rpm, shaft specifications, and approximate dimensions of the motor. Then I turn him loose." "This new motor has terrific torque. It's designed specifically for aircraft propulsion and runs at 2,500 rpm max. I think 20 hp (15 kilowatts) is plenty for this efficient, light airframe. It gives us a lot of extra running time without draining the batteries too quickly. The ULS has such a low sink rate; it only needs 3 kilowatts of power to maintain straight and level flight. That still leaves us with a 12-kilowatt surplus for climbing." Diameter of the clean, compact mill is 9.5 inches, and just 3.5 inches thick! Fishman has logged 20 hours on the ULS personally. He's even done motor-off soaring at his summer home, the Northeast hang gliding mecca of Ellenville, New York. The aircraft comes with a two-blade fixed propeller, but it's also available with a folding carbon propeller, a common feature of high-ticket German motorgliders. Photography by James Lawrence Te ULS' interior is constructed of carbon and aramid materials. Te rudder pedals and seat back are adjustable to accommodate pilots of any height. A four-point seat/shoulder harness are standard equipment. When the motor is shut down in flight, the centrifugally opened prop automatically folds back from the hub like a dragonfly's tail, to dramatically reduce drag. "We're still tweaking the prop," said Fishman. "We had a bit of tip flutter in the earlier, nonfolding prop; it was too noisy. We're working with more carbon/less foam now, which we think will be the solution. It's already showing plenty of thrust and a good climb." His longtime test pilot, soaring enthusiast Joe Bennis, did the initial test hops on the ULS. "Overall control is EAA Experimenter 19

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