Tuesday, November 8, 2011
Light-Sport Chronicles: Snowmobile Engine...NOT!
Kicking the Rotax myth in the head once and for all
"We've got seven technicians: A&P's, an IA, an aeronautical engineer and an electrical engineer. We service and overhaul Rotax aircraft engines and almost everything they're installed in, from certified to LSA to Experimental aircraft. People fly in from all over the country for service. They also ship carburetors, gear boxes and whole engines from as far away as Hawaii and Alaska."
Did he ever have doubts about Rotax?
"No," he answers. "They've always been committed to the aviation side. They're the kind of company that, once they bite into a piece of meat, they don't let go. When they got into the two-stroke snowmobile industry, there were 100 manufacturers, just like the early ultralight-aircraft days. They ended up dominating both markets; they're one of only three snowmobile engine makers now. It's the same with their Sea-Doo watercraft line, which is number one. And they're developing new aircraft engines, too. No, they're in it to stay."
Phil's flight school operates two Rotax-powered Tecnam Super Echos. "One reason was to get firsthand experience of how the engines handle the harsh high-temperature Florida environment. One engine has 1,900 hours, the other 1,800, so both are near TBO, and they'll make it without any problem. Rotax redesigned the crankcase a few years ago, just one of many improvements and refinements they've made over the last 20 years. The company is very responsive to feedback, and as a result, the engines are quite refined."
Now to the $64 million question: How does Rotax stack up to GA engines?
"I think the biggest advantage Rotax has to its nearest competitor, the Continental 0-200, is in size and weight. It's smaller and more compact. The easiest way to really see it is to compare the 82.6-cubic-inch displacement of the 912S to the 200 cubic inches of the Continental. Initially, there was a 100-pound weight difference, although Continental has whittled that down," Phil explains.
The new Lycoming 0-233 with a 213-pound dry weight and 233-cubic-inch displacement represents the traditional powerplant maker's response to the Rotax phenomenon. It's a beautiful engine and weighs 38 pounds less than the IO-235 it replaces for light-sport applications. But it's still an air-cooled engine.
"That's probably the other main advantage of a Rotax," says Phil. "With liquid cooling, we don't worry about shock cooling. And the nickel-silicone (tradename: Nikasil®) coated cylinders don't corrode. They're the same as those in my BMW, which goes 18,000 miles between oil changes and doesn't burn a drop of oil!
"In our school, the Rotax 912 runs at 5000 rpm and needs, at most, half a quart of oil at the 100-hour oil change," Phil continues. "You don't typically see that with Lycomings and Continentals: It's more common to add a quart every eight to 10 hours."
And perhaps the final nail in the "snowmobile myth" coffin: Aeroshell came out with a dedicated oil specifically formulated for the Rotax. "To me, that signified the Rotax had come of age," Phil says.
So, in other words, "Requiescat in pace (R.I.P.), snowmobile."
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