Vibration when flying

Sv.grainne

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We are test flying my Aviomania Genesis and Eric had noticed a vibration at 4200-4600 RPM. What are some suggestions on how to narrow this down? I'm thinking best to start with prop pitch, repitch a small amount and see what that does. I do not have access to a prop balancer. Others have said that some vibration at specific RPM ranges is common.
 
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Mike G

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How did you/Eric arrive at 4200-4600 rpm?
I think you have a 912, so prop imbalance would be nearer 2000 rpm and the blade passing frequency would be around 6000 rpm (assuming 3 blades) so I doubt if it's the prop.
If the 4200-4600 is engine rpm then look at carb balance especially if the vibration reduces with higher revs. If not out of balance crank (unlikely) or engine mounts.
Mike G
 

Sv.grainne

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Readjusted prop, took 1deg off, ran it up on the ground, 5580rpm WOT, no vibration. Eric will fly next week and see if that changes anything.
 
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Aerofoam

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Readjusted prop, took 1deg off, ran it up on the grounds, 6580rpm WOT, no vibration. Eric will fly next week and see if that changes anything.

I've got a couple you can come balance......
 

Tyger

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You corrected it, so nothing to comment on... but what "response" are you talking about?
 
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