X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Fri, 07 Sep 2007 17:48:25 -0400 Message-ID: X-Original-Return-Path: Received: from elasmtp-junco.atl.sa.earthlink.net ([209.86.89.63] verified) by logan.com (CommuniGate Pro SMTP 5.1.12) with ESMTP id 2317449 for lml@lancaironline.net; Fri, 07 Sep 2007 09:53:12 -0400 Received-SPF: none receiver=logan.com; client-ip=209.86.89.63; envelope-from=rtitsworth@mindspring.com DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=dk20050327; d=mindspring.com; b=PUX4riivRK/PUNyuNybFjDhjjizVjK4WNKJsw3dlakFdpW8KjoqFhTVNxQJbOZEP; h=Received:From:To:Subject:Date:Message-ID:MIME-Version:Content-Type:X-Mailer:X-MIMEOLE:Thread-Index:In-Reply-To:X-ELNK-Trace:X-Originating-IP; Received: from [71.238.59.21] (helo=RDTVAIO) by elasmtp-junco.atl.sa.earthlink.net with asmtp (Exim 4.34) id 1ITeG9-0005Tz-Vk for lml@lancaironline.net; Fri, 07 Sep 2007 09:52:34 -0400 From: "rtitsworth" X-Original-To: "'Lancair Mailing List'" Subject: RE: [LML] Re: ES shake (apparently not strut related) X-Original-Date: Fri, 7 Sep 2007 09:52:27 -0400 X-Original-Message-ID: <002401c7f156$53eb9ce0$6400a8c0@RDTVAIO> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0025_01C7F134.CCD9FCE0" X-Mailer: Microsoft Office Outlook 11 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2900.3138 Thread-Index: AcfxN6GYWmXhlLudSEOpSLdtZSrNygAGilng In-Reply-To: X-ELNK-Trace: b17f11247b2ac8f0a79dc4b33984cbaa0a9da525759e265430fa41e16c6f796c300fb0d40359ed1907c87288fcf778e7350badd9bab72f9c350badd9bab72f9c X-Originating-IP: 71.238.59.21 This is a multi-part message in MIME format. ------=_NextPart_000_0025_01C7F134.CCD9FCE0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit FYI, As previously reported, my C172 main gear shakes similar to John's description - primarily during moderate to heavy braking (i.e. an advantage of being able to see the gear on a high wing). I only offer my observations as a reference point. I generally take the pants off in the fall to protect them from snow/ice here in Michigan. While the weight of the pants should effect the natural frequency, the C172 gear seems to shake "about the same" with the pants on or off (primarily during moderate to heavy braking). The pants are solid/stiff to the wheels. I do not know if the pants are balanced for/aft - I'll attempt a crude measurement today (since they are currently now off). I have not attempted to do a run-out measurement on the brake disk nor balance the tires as I'm not really concerned with it on the C172 (perhaps I should be), since I am used to it and it's only a minor nuance on the C172. The C172 gear legs are probably "springy'er" than the ES legs, but are mounted more firmly to the fuselage than many ES legs which have a little "play" in the ES gear leg weldments. I'd guess/speculate that under the correct conditions the main gear vibration could "couple" with the nose gear natural frequency and create/initiate a more violent/catastrophic event (especially if the front ES strut damping circuit were compromised). My C172 has a separate fluid-less Lord shimmy damper (http://www.aircraftspruce.com/catalog/lgpages/lord_shimmy.php) so that part/effect is not comparable to an ES. Rick Titsworth ES-Building, C172-Flying _____ From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of Bill Hannahan Try the taxi tests with wheel pants off. If that eliminates the vibration try to reduce pant weight, especially aft of the axle. The pant attachment should be quite rigid, is it? As a last resort try adding some weight to the nose of the pant. .Are the gear legs crack free and rigidly attached to the airframe? ------=_NextPart_000_0025_01C7F134.CCD9FCE0 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

FYI,

As previously reported, my C172 = main gear shakes similar to John’s description – primarily during moderate to = heavy braking  (i.e. an advantage of being able to see the gear on a high = wing).  I only offer my observations as a reference point.  I generally take = the pants off in the fall to protect them from snow/ice here in Michigan.  While the weight of = the pants should effect the natural frequency, the C172 gear seems to shake = “about the same” with the pants on or off (primarily during moderate to = heavy braking).  The pants are solid/stiff to the wheels.  I do not know if the = pants are balanced for/aft – I’ll attempt a crude measurement today = (since they are currently now off).  I have not attempted to do a run-out measurement on the brake disk nor balance the tires as I’m not = really concerned with it on the C172 (perhaps I should be), since I am used to = it and it’s only a minor nuance on the C172.  The C172 gear legs are = probably “springy’er” than the ES legs, but are mounted more = firmly to the fuselage than many ES legs which have a little “play” in = the ES gear leg weldments.  I’d guess/speculate that under the = correct conditions the main gear vibration could “couple” with the = nose gear natural frequency and create/initiate a more violent/catastrophic = event (especially if the front ES strut damping circuit were compromised).  My C172 = has a separate fluid-less Lord shimmy damper (ht= tp://www.aircraftspruce.com/catalog/lgpages/lord_shimmy.php) so that part/effect is not comparable to an = ES.

Rick = Titsworth

ES-Building, = C172-Flying

 

 

From: = Lancair Mailing List = [mailto:lml@lancaironline.net] On Behalf Of Bill Hannahan
Try the taxi tests with wheel pants off. If = that eliminates the vibration try to reduce pant weight, especially aft of = the axle. The pant attachment should be quite rigid, is it?  As a last resort try = adding some weight to the nose of the pant…  = …Are the gear legs crack free and rigidly attached to the = airframe?

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