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bob27s -> RE: Quiet speed (again) (6/16/2006 3:20:05 PM)
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Hi Dave.....
Id suggest the 60L set up with the the pipe very long, tune it for more around 14,000 to start with. Get the sound measurement. Then if you have margin, shorten the pipe a bit and let the rpm climb.
I currently get 96 db with my Mustang - SJ-46, turbo-jett, 12x4, peaks at 14,100, ground is 13,700. This at 3 meters, on grass.
Hitting 98db at 3 meters (9 feet) is not that hard with the right prop and a real good pipe. The trick is the tip speed and prop noise. Also, consider using a Hyde mount, or other soft engine mount. Those are good for nearly 2db all by themselves on most planes.
Getting the right prop might be the big challenge. A 9x9 would be the smallest I think might work (but we know the 9x9 can turn 16,000 easily on a SJ60L anyway). Might take using a 10x10 and clipping it down a bit, or just running a 10x7 or 10x8.
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