Mailing List flyrotary@lancaironline.net Message #48564
From: Lynn Hanover <lehanover@gmail.com>
Subject: Balls and Springs
Date: Wed, 7 Oct 2009 07:28:37 -0400
To: <flyrotary@lancaironline.net>
 Lynn,
With balancing my single rotor, what would you suggest that I allow ( percentage wise) for oil weight in the rotor - it was suggested to me that I should allow full rotor oil weight.
This discussion suggests otherwise.
George ( down under)
 
George,
 
The process I saw on the internet came from Down there. A rotor is spun up in the lathe with a plastic shield around the outside. Oil is squirted in until it starts spilling out. A pan is slipped under the rotor and the lathe stopped. (if your lathe has a coolant system that would work as well with less mess) The weights are close enough. Then the rotor is laid on a grill on the pan and allowed to drain. Then weigh the liquid in the pan. I bet the balancing people just have a number on the wall for rotaries that is close to that weight. A balancer could do it backwards by spinning the shaft from a factory built engine, with the counterweights mounted, and then add bobweight until he gets a balance. Then subtract the rotor weight from the bobweight and that difference would be the oil allowance.
 
The big name builders all balance to a gnats butt weight, but I just get the rotor weights the same. Never a problem. The single pulse per revolution will be so big that a small balance error will go unoticed. But, its no sin to start out with the balance correct. I have thought about singles and decided that as big a diameter flywheel that you can fit but weighted only at the outer edge. Like 4 sets of starter rings tiged to a flex plate. Even Mazda builds with pieces two weight ranges apart. They have stamped the weights on rotors, and have used colored paint dots. Of course the paint dots are gone when we see a used rotor.
 
Richard Sohn can tell you. He seems to be doing well with his.
 
Lynn E. Hanover
 
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