From: Klusmanp@aol.com
Message-ID: <5a.169dc24e.284d8cac@aol.com>
Date: Mon, 4 Jun 2001 21:15:24 EDT
Subject: Re: LNC2 Elevators fast build
To: lancair.list@olsusa.com
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In a message dated 6/4/01 8:47:36 AM EST, dfs@gateway.net writes:

<< Unless the aero gurus out there can say otherwise, it seems to me that a
 fully counterbalanced, slightly heavy elevator, will have no more tendency
 to flutter than any other.
 
 Dan Schaefer >>


I think this is true of the ELEVATOR itself. However, I believe you can 
induce stab flutter if there is too much weight (from a heavy, fully 
counterbalanced elevator) hanging off the elevator hinges.

Consider a theoretical case of just the stabilizer hanging out in the breeze 
with no elevator attached but a certain amount of lead weight attached to the 
hinges. As you add more lead weight to the aft end of the stabilizer 
eventually it will have a tendency to flutter all on its own. This depends 
upon the amount of stiffness of the structure, the pitching characteristics 
of the airfoil, and the location of the mass with regard to the torsional 
center of the stab.

Considering the stab and elevator combination adds a whole new level of 
complexity to the flutter problem. I really only have a limited understanding 
of the physics involved in this case. I do know that counterbalancing the 
elevator is important, but I believe that the overall weight of the elevator 
is important as well. 

Many years ago I purchased a set of Rutan Longeze plans. Rutan makes it very 
clear that the finished, counterweighted, and painted "elevator" on the 
canard of a Longeze CANNOT be above a certain weight. I'm really surprised 
that the Lancair manual does not have a similar spec.

Paul Klusman
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