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Electric Ultralight

Posted: Mar 01 2019 3:48pm
by X2flier
This is a Mike Sandlin GOAT, a homebuilt FAA-legal ultralight glider, with electric power added. In the USA, no license or inspections are needed for the pilot or the aircraft. Sandlin's Technical Drawings are complete, and free downloads. As a type, we call these ultralight gliders the AirChairs.

Electric GOAT video:

GOAT (glider) homepage:

~4.0KW to sustain level flight. at 110V that would mean 40Amp/hour
The batteries: 22.5v @ 8A/h, 5S5P, 25 batteries @ 1.2 kilos per battery. so 30kg in batteries for 1 hour of powered flight.
The engine, mount and controller weigh ~15kg, so ~45kg for the whole package.
Owner says "As it is, it requires 4.5KW of power on a 49" prop to sustain flight. With 6Kw I get about 200fpm (1 M/S) climb. The motor can handle 45KW max and 22KW sustained, so when my new batteries arrive, I should be able to climb much better. (Maybe too much.. I should have used a smaller/lighter motor). Lots of fun."

The take-off requires the most power, of course; notice that the GOAT here goes up easily on a static tow, pulled by a vehicle.
The flight instrument is probably a Flytek variometer, providing all of that instant performance data. The GOAT would be expected to glide and descend at about -250 fpm (-1.25 M/S), so any number above that comes from engine power or external (thermal) lift. The GOAT (or any ultralight glider or hang glider) can soar for hours on thermal lift only, with no power needed.