Mailing List lml@lancaironline.net Message #42515
From: <vtailjeff@aol.com>
Sender: <marv@lancaironline.net>
Subject: Re: [LML] Re: IV-P Rudder Trim
Date: Wed, 06 Jun 2007 13:13:50 -0400
To: <lml@lancaironline.net>
Lanny,
 
Who's airplane was this. 1" sounds like a lot of movement on an elevator trim tab. I don't even think they travel 1" stop to stop, so how could this be?
 
Jeff
I’m new to the LML site but I have built several aircraft over the years.  One thing that scares me on the Lancair is flutter.  I recently found a IV elevator trim that could easily be moved up and down as much as 1” at the trailing edge.  It turned out to the hinge that the tab was attached to was bending. 



-----Original Message-----
From: Kevin Stallard
To: lml@lancaironline.net
Sent: Wed, 6 Jun 2007 8:34 am
Subject: [LML] Re: IV-P Rudder Trim

I’m not anywhere near an expert on flutter, but isn’t flutter destructive?  I mean if an airframe experiences flutter, it doesn’t just wear out hinges, my understanding is the airframe ceases to be an airframe at that point.  I don’t recall having ever read about any mid-flight break up of a Lancair except those that happen to wander into a thunderstorm here and there.
 
Vibration is completely different and there could be other reasons at “play” regarding the premature wearing of these hinges.  Chris Zavatson has some interesting things on hinges and vibration, give it a read…
 
 
Bottom line, I don’t think flutter in a Lancair is worth worrying about…
 
Kevin
 
 
Scott,
I’m new to the LML site but I have built several aircraft over the years.  One thing that scares me on the Lancair is flutter.  I recently found a IV elevator trim that could easily be moved up and down as much as 1” at the trailing edge.  It turned out to the hinge that the tab was attached to was bending.  The owner had not had a problem with flutter but the hinge was completely worn out due to vibration in only a couple hundred hours.  Lowering the attach point on the horn reduces the leverage and increases the movement of the tab.  This will make it too sensitive and lessen the arm needed to prevent flutter.  I don’t recommend it.
Lanny
 

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