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[FlyRotary] Re: Dynamic
balance
I think your right that the redrive
damper is giving false readings, Ideal would be to spin the prop on an
electric motor, what rpm do you need to balance it ??
Ken
I did that too way back when. I was told
I need to run it's output through a spectrum analyzer. Audio
frequencies so an audio spectrum analyzer would work. You could input
to the audio card in a PC and use a PC audio spectrum analyzer.
The balancer has an optical sensor that picks up from a reflective
piece of tape placed on one blade, to use as a zero reference for
blade position and determine RPM.
Finn Lassen wrote:
Early on I hooked up an accelometer to an
oscilloscope. It sure was a mess - very hard to discern any
fundamental frequency. My conclusiion was that I needed a prop pickup
to trigger the scope and perhaps a notch filter so I would only be
looking at the fundamental frequency of the prop. I never did get back
and try it.
Finn
Perry Mick wrote:
I've used the balancer many times before with no problem on
direct-drive. I think it's getting confused by harmonics or beat
frequencies between the engine and redrive. For a first step it
usually asks for 20-30 grams at a certain radial position, the fender
washer is about right. This is on the prop bolt circle (4.75 inches?),
not out at spinner diameters. It will just be moved around the six
locations temporarily to see if the vibration gets worse or
better.
Perry
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