REFLECTOR: Front Vibration 90% resolved

Rene Dugas dugasd at bellsouth.net
Mon Oct 4 17:16:43 CDT 2004


Removed my "doghouse" to recheck the flange bolts.  Tightened each less
than 1/8th turn.  Already tight.  Bulkhead bolts likewise.  Tight.  It
occurred to me that in flight the canard is lifted slightly at the tips,
Sooooo.   I propped the tips up slightly then rattled the elevators.
There was a vibration and slack not present in the hinges when at rest
on the ground.  I tightened each of l the screws at each hinge to snug
and reflew the plane.  Slight vibration at 188 knots.  Much better.

The slight sag in the canard was compressing the hinges enough to cover
the slack.  In flying configuration the slack was significant only at
speed.  This may be why my vibration did not cease with pull ups.

Thanks for all the help and suggestions.  My plane is a better ship for
your thoughtful suggestions.

 

It occurred to me that in a dramatic pull up the canard could flex
enough to distract at the central hinge and COULD even pop the elevator
torque tube out of the aluminum "L" bracket in the center of the canard.
The circumference of the circle formed by the line through the elevator
is larger than the canard.  The 8 hinges will exert pressure to
neutralize this tendency. The sum of these pressures is unknown to me.
Possibly a second bolt holding the two elevators together is in order
not just the one through the stick connecting rod.

Thoughts?

Rene' Dugas

N129RD

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