Re: Older Rotax 503
David J. Gall
Ron,
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Norm Howell built a sweet Quickie called the "Ugly Quickling" in the 80's. He set some records in it with his highly modified Onan (not fire-breathing, just intake, exhaust, and >>lotsa good cooling mods<< hint hint). After he got tired of the Onan (poor climb), he switched to a Rotax 503 with a 2.00:1 gearbox. I think he used the Miller-style cowl. The gearbox necessitated a tiny prop, with quite high pitch. The climb was a little better than with the Onan, but the cruise speed was way up there. I don't recall a solid number from anything published, but IIRC there was something about 150mph at 50% power and some talk about the airframe redline being around 170mph and that being easily do-able at cruise.... I'd have to look things up to verify all the foregoing so don't take it as gospel. Do your own research. Sport Aviation magazine Sept. 1987 page 48 for the Onan powered version. Q-Talk back issues for the Rotax upgrade info (sorry, I don't have issue numbers). BTW, I have a 503 set aside for my Quickie for after the Onan scares me too much. The oil injection is a necessity in my opinion. The non-injected engines rely on the fuel mix for lubrication and at high airspeed/low throttle, the lubrication just isn't enough for the high RPM at which the prop is turning the engine such as during descent (like on that mock strafing run!). With oil injection, the oil delivery is metered in part by throttle setting and in part by RPM, so at low throttle/high RPM you get a "richer" oil mix and (hopefully!) adequate lubrication. Of course, ultralights don't suffer the 'detriment' of high speeds so ignore your ultralight buddies' advice on this issue. Also, ignore the ultralight prop manufacturer's recommendations (Powerfin, Ivo, Warp, etc.) and get a Catto prop (or equivalent) for your 503 SuperQuickie.... David J. Gall
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