aileron servo instl vs vibration

[Jerry Budd]

Hi Xavier,

A while back Dave von Linsowe tried side mounting the aileron servos 
to see if the servo pots would be more tolerant of the motor 
vibration.

The theory was that the rotary acceleration forces induced by the 
motor on the airframe translate into increased vertical acceleration 
at the aileron servos causing the pot wiper preload to vary 
cyclically, resulting in increased rate of wear.  It was hoped that 
the pot wear could be reduced or eliminated by orienting the plane of 
rotation of the pot wiper in the vertical axis.

It didn't help.  Tony Frackowiak also tried it on his Gator G-202 and 
it didn't work there either.

And that makes sense, as the pot wiper preload is not likely to be 
affected by the inertial forces acting on the very low mass of the 
pot wiper.

The current thought is that the inertial forces acting on the 
ailerons are back fed into the aileron servo gear train causing the 
aileron servos to have to work almost constantly to resist the 
uncommanded movement.  The servo moves slightly (but nearly 
continuously) around the commanded position to resist causing 
excessive wear on the pot and gears (similar to servo buzz).  Since 
the servo spends most of its time around neutral, that's where most 
of the wear occurs.

Interestingly, the ePartner Tony Frackowiak is flying shows no 
aileron servo pot wear through ~40 flights (go figure!).

Jerry


>Is there a prefered method to install the aileron servos and protect them
>from the high level of vibration someone was mentioning?
>Could the servo be mounted on his side with the arm parralele to the ribs
>wihout risking more wear of the gear ?
>I suppose the vibration on the wing servo is mainly up-down
>
>Thanks
>
>Xavier

-- 
___________
Jerry Budd
mailto:jbudd at qnet.com
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