X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Sun, 26 Aug 2007 14:03:39 -0400 Message-ID: X-Original-Return-Path: Received: from vms044pub.verizon.net ([206.46.252.44] verified) by logan.com (CommuniGate Pro SMTP 5.1.11) with ESMTP id 2285752 for lml@lancaironline.net; Sun, 26 Aug 2007 13:06:40 -0400 Received-SPF: pass receiver=logan.com; client-ip=206.46.252.44; envelope-from=skipslater@verizon.net Received: from wbs ([71.177.5.162]) by vms044.mailsrvcs.net (Sun Java System Messaging Server 6.2-6.01 (built Apr 3 2006)) with ESMTPA id <0JNE003TY4TSOMX3@vms044.mailsrvcs.net> for lml@lancaironline.net; Sun, 26 Aug 2007 12:05:53 -0500 (CDT) X-Original-Date: Sun, 26 Aug 2007 10:04:57 -0700 From: "Skip Slater" Subject: Re: [LML] Re: ES Strut issues X-Original-To: "Lancair Mailing List" X-Original-Message-id: <003201c7e803$5c27b300$0301a8c0@wbs> MIME-version: 1.0 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2900.3138 X-Mailer: Microsoft Outlook Express 6.00.2900.3138 Content-type: multipart/alternative; boundary="----=_NextPart_000_001D_01C7E7C8.8E75AAA0" X-Priority: 3 X-MSMail-priority: Normal References: This is a multi-part message in MIME format. ------=_NextPart_000_001D_01C7E7C8.8E75AAA0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Jim, My shimmy symptoms sound identical to yours - same onset speed, same = results from releasing and smoothly re-applying brakes. To me, my butt = says the shaking is coming from the nose, but I know from my first = experience when I had a witness that the origin may be from one or both = of the mains, which seems to translate forward. =20 Like Mike Easley, I'll hold aft stick as I roll out to keep as much = weight as possible off the mains during rollout. I also retract the = flaps as soon as I'm on the ground to put more weight on the mains. I = think that also takes a bit of weight off the nose. I haven't really = taken notice of the effect of a more aft CG on the shaking, but I'll pay = more attention to that in the future. If I have a short runway (like the 2000' one we use for our Young = Eagles events), I land on-speed and do heavier braking as soon as I'm on = the ground, which gives me a lot of deceleration before the shimmy = onset. That results in a much shorter landing rollout. I don't have a taxi speed that I avoid, though I can get a shaking if = I try to brake lightly at low taxi speeds. I don't get any shimmy at = all when taxiing with the brakes off.=20 The surprising thing to me is what a well known issue this is and the = lack of a solution for it. You'd think that between some of the = engineering types who are flying ES's and the factory guys, someone = would have put their finger on exactly what causes this and come up with = a fix. I think Lancair has chosen to bury their heads in the sand on = this other than to equip the new kits with a beefier nose strut. But = there are a lot of old struts flying out there and at least three of = them that I know of have had catastrophic failure, two resulting in = collapsed nose gears, broken mounts and $50K+ in damage. In the other = case, it was a miracle that the strut didn't fold, as the post flight = tear down of the strut revealed a total failure of one of the damping O = rings. Maybe your video tests will point us in the right direction. I sure = hope so! Skip ------=_NextPart_000_001D_01C7E7C8.8E75AAA0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

Jim,

My shimmy symptoms sound = identical to=20 yours - same onset speed, same results from releasing and smoothly = re-applying=20 brakes. To me, my butt says the shaking is coming from the nose, = but I=20 know from my first experience when I had a witness that the origin may = be from=20 one or both of the mains, which seems to translate forward. =

Like Mike Easley, = I'll hold aft=20 stick as I roll out to keep as much weight as possible off the mains = during=20 rollout. I also retract the flaps as soon as I'm on the ground to = put more=20 weight on the mains. I think that also takes a bit of weight off = the=20 nose. I haven't really taken notice of the effect of a more aft CG = on the=20 shaking, but I'll pay more attention to that in the future.

If I have a short runway = (like the=20 2000' one we use for our Young Eagles events), I land on-speed and do = heavier=20 braking as soon as I'm on the ground, which gives me a lot of = deceleration=20 before the shimmy onset. That results in a much shorter landing=20 rollout.

I don't have a taxi speed = that I=20 avoid, though I can get a shaking if I try to brake lightly at low taxi=20 speeds. I don't get any shimmy at all when taxiing with the brakes = off.

The surprising thing to me = is what a=20 well known issue this is and the lack of a solution for it. You'd = think=20 that between some of the engineering types who are flying ES's and the = factory=20 guys, someone would have put their finger on exactly what causes = this and=20 come up with a fix. I think Lancair has chosen to bury their heads = in the=20 sand on this other than to equip the new kits with a beefier nose = strut. =20 But there are a lot of old struts flying out there and at least three of = them=20 that I know of have had catastrophic failure, two resulting in = collapsed=20 nose gears, broken mounts and $50K+ in damage. In the other case, = it was a=20 miracle that the strut didn't fold, as the post flight tear down of the = strut=20 revealed a total failure of one of the damping O = rings.

Maybe your video tests = will point us=20 in the right direction. I sure hope so!

= Skip

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