X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Fri, 16 Sep 2005 22:18:36 -0400 Message-ID: X-Original-Return-Path: Received: from imo-d21.mx.aol.com ([205.188.144.207] verified) by logan.com (CommuniGate Pro SMTP 5.0c2) with ESMTP id 724734 for lml@lancaironline.net; Fri, 16 Sep 2005 22:12:31 -0400 Received-SPF: pass receiver=logan.com; client-ip=205.188.144.207; envelope-from=Sky2high@aol.com Received: from Sky2high@aol.com by imo-d21.mx.aol.com (mail_out_v38_r5.5.) id q.f6.590fe2ed (48576) for ; Fri, 16 Sep 2005 22:11:43 -0400 (EDT) From: Sky2high@aol.com X-Original-Message-ID: X-Original-Date: Fri, 16 Sep 2005 22:11:43 EDT Subject: Re: [LML] Re: LNC2 elevator hinges X-Original-To: lml@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="-----------------------------1126923103" X-Mailer: 9.0 Security Edition for Windows sub 5009 X-Spam-Flag: NO -------------------------------1126923103 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit In a message dated 9/16/2005 8:51:10 P.M. Central Standard Time, marv@lancaironline.net writes: Excessive wear is the very nature of aluminum in a hinge environment. The wear is not on the pin, but rather on the inside diameter of the hinge itself. Aluminum is a relatively soft material and it corrodes easily. Logically as the aluminum wears away on the inside diameter that houses the pin, you would conclude that the slop would increase over time. Flutter is caused by unbalanced control surfaces. I don't think loose pins would necessarily lead to flutter, but perhaps, if there is a minor imbalance, movement allowed between the control surface and airframe via a sloppy fitting hinge could move you closer to destructive flutter. John, The issue of hinge looseness is not about flutter per se. It doesn't take much looseness in the LNC2 aileron hinges to be reflected in the "lash" in what should be a very tight system. With tight hinges, if one clamps one aileron and moves the other, one would see 1/8 to 1/4 inch of movement, a measure of the lash inherent in any system consisting of 2 times several push-rods with bearing rod ends, bell cranks with bearing pivots and hinges that are another pivot point. With loose hinges alone (my airplane, prior pins) that lash could be 1/2" to 5/8", depending on how much force is applied. One compensation for any lash is to rig the ailerons a bit high so as to put a wee air load on both, thus eliminating sloppy movement that could be potentially excited by airframe vibration. For me, another assist is the use of a servo driven spring trim system which also places a small tension on the aileron control system. I am not experiencing "flutter" at the outboard elevator hinges, but a peculiar movement that excites the horizontal stab. If carbhinges would have been available when I was building the wings (Um, 1991-92) I would have considered them although my education took flight only after flight. I would not consider installing them now, after the paint has dried. I would rather like to investigate my minor "problem." Scott Krueger AKA Grayhawk Lancair N92EX IO320 SB 89/96 Aurora, IL (KARR) -------------------------------1126923103 Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable

In a message dated 9/16/2005 8:51:10 P.M. Central Standard Time,=20 marv@lancaironline.net writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000=20 size=3D2>Excessive wear is the very nature of aluminum in a hinge=20 environment. The
wear is not on the pin, but rather on the= =20 inside diameter of the hinge
itself. Aluminum is a relativ= ely=20 soft material and it corrodes easily.
Logically as the aluminum=20 wears away on the inside diameter that houses the
pin, you would= =20 conclude that the slop would increase over time. Flutter is
= ;=20 caused by unbalanced control surfaces. I don't think loose pins=20 would
necessarily lead to flutter, but perhaps, if there is a mi= nor=20 imbalance,
movement allowed between the control surface and airf= rame=20 via a sloppy
fitting hinge could move you closer to destructive=20 flutter.

John,

The issue of hinge looseness is not about flutter per se. It does= n't=20 take much looseness in the LNC2 aileron hinges to be reflected in the=20 "lash" in what should be a very tight system. With tight hinges, if on= e=20 clamps one aileron and moves the other, one would see 1/8 to 1/4 inch of=20 movement, a measure of the lash inherent in any system consisting of 2 times= =20 several push-rods with bearing rod ends, bell cranks with bearing pivots and= =20 hinges that are another pivot point. With loose hinges alone (my airpl= ane,=20 prior pins) that lash could be 1/2" to 5/8", depending on how much force is=20 applied. One compensation for any lash is to rig the ailerons a bit hi= gh=20 so as to put a wee air load on both, thus eliminating sloppy movement t= hat=20 could be potentially excited by airframe vibration. For me, another as= sist=20 is the use of a servo driven spring trim system which also places a small=20 tension on the aileron control system.

I am not experiencing "flutter" at the outboard elevator hinges, but a=20 peculiar movement that excites the horizontal stab.

If carbhinges would have been available when I was building the wings (= Um,=20 1991-92) I would have considered them although my education took flight only= =20 after flight. I would not consider installing them now, after the pain= t=20 has dried. I would rather like to investigate my minor "problem."

Scott Krueger=20 AKA Grayhawk
Lancair N92EX IO320 SB 89/96
Aurora, IL=20 (KARR)

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