Re: prop balance

[Mi Vida Loca]

At 10:06 PM 12/28/98 -0800, you wrote:
>Huh???
>Don't understand this. Prop balancing is done completely independent of
>the engine. At least it has always been done that way where I come from.
>Have I been missing something?
>
>I recommend a complete overhaul of the prop to bring it back up to factory
>specs before engine run-in. This assures any adverse vibrations will be
>coming from the engine during run-in. Besides, the prop is probably almost
>as old as the plane and to put an old unbalanced prop on a new engine
>doesn't seem the wise thing to do.
>Dan

Yes you have missed something, there is the balance that is done while a prop is being overhauled. This balances the prop itself then there is a process known as dynamic balancing. This is done with the prop mounted on the engine some what like balancing the tires on your car. This is suppose to reduce vibration in the engine as well as the prop. Since the prop is just a giant flywheel it does make a certain amount of sense. 90% of the vibration most people really feel is more attributable to the engine than the prop itself. These little engines are really crude and nothing is in balance internally. I saw a test of crank balance between 3 cranks that had come off the assembly line in order. Not one was even close to the others in balance. No automaker would accept this sort of production standard but the aviation industry not only accepts it but has continued to accept it for over 50 years.


Dave
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