OS .52 four stroke over prop
07-08-2004, 09:15 AM
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OS .52 four stroke over prop
Arizona Models suggest using an 18-8 on an OS 52 with their 1/5 size Dr.1. (7 lbs.) Sounded wrong, called them to confirm. Tried it on a trainer and wow! Top rpm 4000 idles at 1300. Lots of pull, just slow flight. (had to hand launch the trainer for prop clearance.) What if any long term effect or damage could this cause?
07-08-2004, 09:45 AM
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RE: OS .52 four stroke over prop
Such a large propeller on your engine would severely stress the connecting rod and bearings. The piston will also take a beating. Expect tuning problems and vibration-derived problems. The engine isn't designed to run at that RPM at full throttle. It should be propped to turn in the mid-to high-9,000's, or low 10,000's. If you continue to run your enigne with that loading and at that full-throttle RPM, don't expect it to have a particularly long service life. Such use would also be considered "abuse" of the enigne, and an early demise would not be covered under the warranty.
07-08-2004, 01:21 PM
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RE: OS .52 four stroke over prop
I just downloaded the instructions for that plane, and it doesn't say to use an 18x8 prop on a .52 4-stroke anywhere. They suggest the 18x8 prop for the Astro 40 ELECTRIC motor, presumably with the appropriate gear ratio.
