aileron servo instl vs vibration

Paul Horan phoran at vvm.com
Sat Feb 21 08:29:38 AKST 2004


Jerry,
    If such is the case, wouldn't static balancing the ailerons for no load relieve this ?
Is Tony's plane set up like this ?
Thanks,
Paul
----- Original Message ----- 
From: "Jerry Budd" <jbudd at QNET.COM>
To: <discussion at nsrca.org>
Sent: Saturday, February 21, 2004 11:11 AM
Subject: Re: aileron servo instl vs vibration


> 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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