Sender: <marv@lancaironline.net> (Marvin Kaye)
To: lml
Date: Mon, 09 Dec 2002 19:40:19 -0500
Message-ID: <redirect-1898365@logan.com>
From: RWolf99@aol.com
Subject: LNC2 Aileron Balance
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I called Carsten a while back and he told me that they normally have the lead 
weights going full span on the LNC2 ailerons.  I was able to balance mine 
with about half that.  I had lead on both sides of the leading edge -- maybe 
Carsten only had weights on the forward face (this would explain the 
difference).  I have not weighed my completed aileron but I, too, was 
surprised at how heavy it was.

I also put two half moon reinforcers in.

To clarify Ric Argente's comment, we are trying to balance the aileron so 
that the CG is on the hinge line.  "Overbalanced" means that the CG is 
forward of the hinge line and the trailing edge wants to be above the neutral 
position.  That is the safe direction and incurs a weight penalty but has no 
safety implications.  "Underbalanced" means that the weight is behind the 
hinge line and the trailing edge wants to be hanging below neutral.  This 
does not guarantee that the aileron will flutter, but it could.  As a result, 
we slightly overbalance such that when the surface is painted, we are at 
least "100% balanced", meaning that the CG is on the hinge line and the 
aileron wants to hang level, and there is no risk of flutter and no 
superflous weight.

It is okay to remove excess lead after painting to get from a slightly 
overbalanced situation to 100% balanced (as Bob Smiley suggests) but I'm not 
sure I'd bother, unless the aileron were way overbalanced.

You should understand the flutter implications fully, or at least go to gret 
pains to ensure that the surfaces are at least 100% balanced.  More than that 
doesn't do you any good.  Less than that can kill you.  I would also suggest 
that your friendly Lancair inspector will not be able to determine whether 
you are 100% balanced or not without yanking the surfaces and verifying that 
himself.  He can only see if there is weight on there -- not whether it is 
too much or too little.  (You inspectors can chime in here if I've 
misrepresented this.)  So make sure you get this right -- this is a 
safety-critical issue.

Yeah, I'd probably save many more pounds of weight by going on a diet than I 
could ever save with airframe weight reductions, but I'd rather spend $200 to 
save half a pound of Lancair empty weight by buying some gizmo than give up 
my Starbucks Iced Mochas....

- Rob Wolf
LNC2 51% (I closed the tail over Thanksgiving...I figure that's worth 1%...)