Mailing List lml@lancaironline.net Message #14927
From: <Sky2high@aol.com>
Sender: Marvin Kaye <marv@lancaironline.net>
Subject: Re: [LML] Re: delaminations of aileron counterweight web LNC2
Date: Wed, 21 Aug 2002 11:34:35 -0400
To: <lml>
Greg,

You pass.  Note, I am not an engineer.  I agree with the possibilities you have outlined, except that it doesn't occur in most cases.  Well, let me qualify that.

Lancair's original design did not require stiffening webs.  I think any weight oscillations are damped by the arm hitting the wing trailing edge but my tight fitting curves show no wear from hitting the lower wing skin trailing edge.

Your concerns are more understandable if the airplane:

1. Was a fast build kit.
2. Has extended fuel bays.
3. Has extended wing tips.
4. Has an aileron mounted trim tab.
5. Ailerons weren't rebalanced after final painting.
6. Airframe experiences excessive vibration from unbalanced engine/prop combo.
7. "Lash" in aileron control system left unchecked.

I am fortunate that I didn't have to concern myself with the first 6 items.  My trim is thru a servo controlled spring-bias system which places a very small load on the ailerons.  I also rigged the ailerons to both fly ever so slightly high so there is a airstream load on them at all times - this eliminates vibration from being induced because of the many rod-end linkages.  Clamp one aileron, go move the other and note the amount of displacement, an indication of lash.  When cruising, an unloaded aileron can then "flap in the breeze".

Believe me, I am very interested in why your webs delaminated - as a Lancair pilot and as an EAA Tech Counseler.

Scott Krueger
N92EX

PS I have been to 235 Kt dives and raced at an excess of 200 KIAS (in turbulence) without a problem.  Most Lancairs do not have the stiffening webs.
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