REFLECTOR: Take Off Shimmy

[Brett Ferrell]

Yup, we noted the same thing.  Just assumed that it was a harmonic as it
slowed down with little load on it.  We did balance the wheel
kind-a-sort-a, but probably should do a more precise job of it.

B

tstockmn at aol.com wrote:
> Velocitites
>
> For those of you flying fixed gear birds, I've got a question.   I
> recently replaced the rubber shock mount on my front gear strut with
> the "new" rubber mount due to suffering three failures of the factory
> mount.     So far no shimmy on landing or on the take-off roll.   
> However . . . . . . I've notice that as a I climb out the first 500
> feet or so, I experience a "shimmy" that starts about five to ten
> seconds into flight and then dissipates after 5-10 seconds.  You feel
> it in the fuselage, but no in the stick or rudder pedals.    It only
> happens on takeoff and I can't reproduce it in flight while simulating
> takeoff or anything else.    Nothing else has been done to the plane
> (600+ hrs TTAF) recently other than the gear mod.  I checked all the
> flying surfaces and not indication of flutter.   Prop tight, motor
> mounts good.   I even put the brakes to see if it wa! s the main
> wheels turning causing the shutter.    My rule of thumb is that the
> most likely cause of a problem is normally the last thing you
> "fixed."    I suspect it is either due to the front wheel spinning
> down and being slightly off balance or some other transitory vibration
> coupled with the spinning wheel.     My guess is that the previous
> nose gear installation was loose enough that it didn't transfer any
> shimmy or vibration once the wheel left the ground.    Now with the
> new rubber shock mount, the nose gear is solidly pressed against the
> fuselage (though the bumper and capture plate) and it amplifies any
> transient vibration.   
>
> Any suggestions or anyone have a similar problem.   
>
>
> Bill  Stockman    173FGE   N12WS
>
> "no good repair goes unpunished"
>
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