The cost of dynamic prop balancing has caused me to begin investigating a
homebuilt method using available technology:
Analog Devices make an accelerometer evaluation kit (ADXL05EM, $100)which
measures acceleration to 5 G in one axis. This unit is about 2" X 2" X 1"
plus mounting tabs and a 3 foot long cable. Seems like this could be bolted
temporarily to the Rotax gearbox to measure vibration. Painting a white
stripe on the back of the spinner backplate and mounting a photo pickup
adjacent would provide a sync signal for an oscilloscope, allowing a view of
engine vibration vs prop angle. This should provide guidance on where to
place washers and, with a bit of experience, how many are needed.
My understanding of the equipment used to dynamically balance props is that
it is similar to the arrangement described above. One possible problem with
this homemade version is interference from the ignition, although careful
sheilding should handle this.
Has anyone tried anything along these lines, and what were the results?
John A044
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