Experimenter

FEB 2015

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.

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EAA Experimenter 23 Dave Atkins may have more hours fl ying behind a rotary en- gine than anyone else. His company does not make PSRUs, but just about everything else rotary is available. www.AtkinsRotary.com T WO-STROKE ENGINES While we may go far afi eld, we should remind you that two- stroke engines are still available. In fact, a used two-stroke can be the least expensive power to fl y. It is not possible to match a two-stroke engine's power-to-weight ratio at a reasonable cost, especially at the lower power end. The smaller Wankels can match the power-to-weight ratio but are pricey. Polini makes some interesting two-stroke, single-cylinder engines. James Wiebe of Belite Aircraft had good things to say about this not-inexpensive Italian engine. www.Polini.com/en/ page_719.html Simonini, also from Italy, makes a line of two-stroke engines frequently used by powered paragliders. www.SimoniniUSA. com/?page=HomePage Hirth from Germany makes a full line of two-strokes. www.Hirth-Motoren.de/en/home.html Compact Radial Engine, based in British Columbia, is one of the few North American manufacturers of engines for light aircraft. Leon has a very interesting fl at twin in the works. www.CompactRadialEngines.com/index.html Rotax still makes the 582 two-stroke. I wonder if Rotax has tried direct fuel injection on the 582. www.FlyRotax.com/ enginesImpressum/product-range.aspx While it would be a hard sell to conservative aviators, a mod- ern two-stroke engine is, I feel, the best technical choice for light planes needing 100 hp and below. The key features necessary would be computer-controlled, direct-in-cylinder fuel injection, and liquid cooling. These technologies are used on two-stroke engines for snowmobiles and outboards. They are also used for some unmanned aerial vehicle (UAV) engines, in part to enable them to use heavy fuels, but have not appeared on any two- strokes for sport aviation use. Rotax and Hirth have the technol- ogy, but as of yet, have not made it available for us. Hirth has almost the perfect engines for direct fuel injec- tion. Their 80- and 100-hp, liquid-cooled, in-line three-cylinder engines would be ideal for conversion to direct injection. The three-cylinder, two-stroke engine can produce good power with a more compact exhaust system than other two-stroke engine confi gurations. Such engines would be lighter than the Rotax four-strokes, more compact, less expensive, and potentially, with lower fuel consumption. Lycoming has a similar heavy-fuel two-stroke for UAV use. You'd have to ask Lycoming if a gasoline version could be sold at a reasonable price. At the low end of the power spectrum are engines designed for the backpack-mounted power packages for paragliders. From about 15 hp, they can range to more than 30 hp and have to be lightweight and compact, so they are normally single-cylinder, air-cooled two-strokes. There are a few liquid-cooled fl at twins or four-strokes. There are some very nice single-seat aircraft from Europe that will fl y quite well on about 25 to 35 hp. The 350- to 400-hp plus EPS Diesel is the wave of the future for the heavier end of light planes. It is only a bit heavier and more expensive than a gas engine, but it has a much lower fuel burn of a less expensive fuel. Comparable turboprops are lighter, much more expensive, and use twice the fuel. Eric Raymond's Sunseeker Duo points to the future of sport fl ight with no fuel needed and very little noise. Hopefully the price of solar cells and batteries will become affordable in the near future.

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