X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Mon, 27 Aug 2007 23:33:32 -0400 Message-ID: X-Original-Return-Path: Received: from fmailhost02.isp.att.net ([207.115.11.52] verified) by logan.com (CommuniGate Pro SMTP 5.1.11) with ESMTP id 2288411 for lml@lancaironline.net; Mon, 27 Aug 2007 20:57:29 -0400 Received-SPF: pass receiver=logan.com; client-ip=207.115.11.52; envelope-from=poprundell@bellsouth.net Received: from lanny (adsl-155-229-122.shv.bellsouth.net[72.155.229.122]) by bellsouth.net (frfwmhc02) with SMTP id <20070828005651H0200eqfhue>; Tue, 28 Aug 2007 00:56:51 +0000 X-Originating-IP: [72.155.229.122] From: "lanny" X-Original-To: "'Lancair Mailing List'" Subject: RE: [LML] Re: ES Strut issues X-Original-Date: Mon, 27 Aug 2007 19:56:27 -0500 X-Original-Message-ID: <000001c7e90e$4484b430$6101a8c0@Lanny> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0001_01C7E8E4.5BAEAC30" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.2627 Importance: Normal In-Reply-To: X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3138 This is a multi-part message in MIME format. ------=_NextPart_000_0001_01C7E8E4.5BAEAC30 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Jim, I would like to put my 2 cents in on your shimmy. Most of my experience has been with Glasairs but the causes of shimmy are usually pretty much the same. I have test flown 3 ES's and experienced a shimmy with the second one. That airplane was cured by going to a thicker more viscose strut oil. The nose gear has a controlled leak from one side to the other side of a divider that restricts movement. Using a heavier oil sometimes will fix it. Vern advised me of this years ago and I simply went to a motorcycle shop and purchased 30 wt strut oil. Your problem sound more like it is coming from the main gear. I experienced this same type shimmy in a new Glasair SIIS-RG a couple of years ago. It drove me up the wall. I tried everything. I tightened the friction clamp on the nose gear until I could hardly taxi it. I tried more air pressure and less air pressure. I tried forward and aft C/G solutions, etc. It always happened when I got on the brakes and stopped when I got off. Finally I had a good friend taxi the airplane up to about 60 knots and get on the brakes while I stood on the side of the runway with a camera. I didn't need the camera. Shortly after the brakes were applied the right main gear started jumping up and down like it had a 10 pound weight tied to one side of the wheel. I couldn't believe it. This was the first Glasair we had ever worked on that came from the factory with new Grove Brakes. I called Grove and told him what had happened. He immediately said the brakes were too small. He sent me the proper brakes and the problem went away forever. Turns out Glasair has sent brakes for the Glastar by mistake. Another possibility is extreme heat caused by the closely fit wheel pants. This would explain the warping of the disc. I noticed the newer ES kits come with a recessed area on the inboard side of the pant for venting. Hope this helps. Lanny -----Original Message----- From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of Jim Scales Sent: Saturday, August 25, 2007 4:36 PM To: lml@lancaironline.net Subject: [LML] Re: ES Strut issues Gary, I checked the alignment on the strut when I reinstalled it during the annual. It is set right at 1.5 front to rear, 0 side to side. I agree with you that there is something in the ES that is prone to produce this shake. Finding it is the difficult part. I believe that whatever it is the flaw is present in most of the ES models that are flying. There are too many reports of this problem for it to be coincidence. Thanks, Jim ----- Original Message ----- From: Gary Casey To: lml@lancaironline.net Sent: Saturday, August 25, 2007 9:07 AM Subject: [LML] Re: ES Strut issues Jim, Since you have done all the logical things without effect, I'm wondering if there isn't something "built-in" that is causing the problem, like geometry. The only geometry issue I can think of is the strut rake angle. The correct angle was the subject of some debate a while back. All I know is that I set mine at +1.5 degrees (lower end forward) and I have never had a trace of shimmy. The previous discussion, as I recall didn't result in a definitive answer, but 0 to +1.5 or so seemed to be the "correct" rake angle. I have the rebuilt strut since new and have a different engine mount (for a Lycoming) and either of those might make a difference, although I'm pretty sure my engine mount is not more rigid than the standard one. While my strut is not held laterally any better it is probably more rigid in the fore-and-aft direction because of the different drag link design. Gary Casey ES #157 ------=_NextPart_000_0001_01C7E8E4.5BAEAC30 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

Jim,

I would like to put my 2 cents in = on your shimmy.  Most of my = experience has been with Glasairs but the causes of shimmy = are usually pretty much the same.  I = have test flown 3 ES’s and experienced a shimmy = with the second one.  That airplane = was cured by going to a thicker more viscose strut = oil.  The nose gear has a controlled = leak from one side to the other side of a divider that restricts movement.  Using a = heavier oil sometimes will fix it.  = Vern advised me of this years ago and I simply = went to a motorcycle shop and purchased 30 wt strut = oil.

Your problem sound more like it is = coming from the main gear.  I = experienced this same type shimmy in a new Glasair = SIIS-RG a couple of years ago.  It = drove me up the wall.  I tried = everything.  I tightened the friction clamp = on the nose gear until I could hardly taxi it.  I tried more air pressure and less air pressure.  I tried forward and aft C/G = solutions, etc.  It always happened = when I got on the brakes and stopped when I got off.  Finally I had a good friend taxi = the airplane up to about 60 knots and get on the brakes while I stood on the = side of the runway with a camera.  = I didn’t need the camera.  Shortly = after the brakes were applied the right main gear started jumping up and down like = it had a 10 pound weight tied to one side of the wheel.  I couldn’t believe = it.  This was the first Glasair we had ever worked on that came from the factory with new Grove Brakes. =  I called Grove and told him what = had happened.  He immediately = said the brakes were too small.  He = sent me the proper brakes and the problem went away forever.  Turns out Glasair has sent brakes for the Glastar by = mistake.  Another possibility is extreme = heat caused by the closely fit wheel pants.  This would explain the warping of the disc.  I noticed the newer ES kits come with a recessed area on the = inboard side of the pant for venting.

Hope this = helps.

Lanny

 

-----Original = Message-----
From: Lancair Mailing = List [mailto:lml@lancaironline.net] On = Behalf Of Jim Scales
Sent: Saturday, August = 25, 2007 4:36 PM
To: = lml@lancaironline.net
Subject: [LML] Re: ES = Strut issues

 

Gary,

 

I checked the alignment on the strut when I reinstalled it during the annual.  It is set right at 1.5 front to rear, 0 side to = side.  I agree with you that there is something in the ES that is prone to = produce this shake.  Finding it is the difficult part.  I believe that = whatever it is the flaw is present in most of the ES models that are flying.  There are too many reports of this problem for it to be coincidence.

 

Thanks,

 

Jim=

----- Original Message -----

From: Gary Casey

Sent: Saturday, = August 25, 2007 9:07 AM

Subject: [LML] Re: ES Strut issues

 

Jim,

Since you have done all the logical things without effect, I'm wondering if = there isn't something "built-in" that is causing the problem, like geometry.  The only geometry issue I can think of is the strut rake angle.  The correct angle was the subject of some debate a while back.  All I know is that I set mine at +1.5 degrees (lower end = forward) and I have never had a trace of shimmy.  The previous discussion, = as I recall didn't result in a definitive answer, but 0 to +1.5 or so seemed = to be the "correct" rake angle.  I have the rebuilt strut since = new and have a different engine mount (for a Lycoming) and either of those = might make a difference, although I'm pretty sure my engine mount is not more = rigid than the standard one.  While my strut is not held laterally any = better it is probably more rigid in the fore-and-aft direction because of the = different drag link design.

Gary Casey

ES #157



 

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