8411SA oscillation

[Scott Smith]

I had the same problem not too long ago.  Turned out the tail wheel steering
spring was just strong enough to sustain the oscillations.  The fix was to
remove the spring and install a piece of yellow nyrod for a tiller.

I've also seen pieces of foam installed under the rudder servo control horn
to provide some dampening.

Scott
  -----Original Message-----
  From: discussion-request at nsrca.org [mailto:discussion-request at nsrca.org]On
Behalf Of Keith Black
  Sent: Monday, August 23, 2004 12:24 AM
  To: discussion at nsrca.org
  Subject: 8411SA oscillation


  I have a new JR 8411SA on the rudder of my new plane and it frequently
oscillates back and forth.

  In the past I've experienced oscillation problems on the rudder using a JR
8411SA, however when this has occurred in the past (with a relatively new
servo) it normally indicated that the pull-pull cables are a bit loose and
tightening them will solve the problem.

  However, in this case I've tightened the cables quite a bit tighter than
my other plane and still have the oscillation problem even with the new
servo. If I touch the rudder with my hand it will stop, and I can also stop
it by moving the stick back and forth a couple of times very slowly.
However, any quick moves of the rudder stick to center, or when the plane is
first turned on will result in the oscillation.

  As far as flying goes, I imagine that the prop wash normally stops the
oscillation, much like putting my hand on the rudder, but the fact that this
occurs so much and my other plane doesn't often have this problem is
somewhat troubling.

  Any suggestions or advice?

  Thanks,
  Keith Black
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