X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Wed, 08 Jul 2009 11:16:04 -0400 Message-ID: X-Original-Return-Path: Received: from imr-ma03.mx.aol.com ([64.12.206.41] verified) by logan.com (CommuniGate Pro SMTP 5.2.14) with ESMTP id 3749031 for lml@lancaironline.net; Wed, 08 Jul 2009 07:52:39 -0400 Received-SPF: pass receiver=logan.com; client-ip=64.12.206.41; envelope-from=MikeEasley@aol.com Received: from imo-ma02.mx.aol.com (imo-ma02.mx.aol.com [64.12.78.137]) by imr-ma03.mx.aol.com (8.14.1/8.14.1) with ESMTP id n68Bptiw025842 for ; Wed, 8 Jul 2009 07:51:55 -0400 Received: from MikeEasley@aol.com by imo-ma02.mx.aol.com (mail_out_v40_r1.5.) id q.bf2.5657aff0 (37519) for ; Wed, 8 Jul 2009 07:51:51 -0400 (EDT) Received: from MikeNotebook (c-76-25-136-43.hsd1.co.comcast.net [76.25.136.43]) by cia-ma08.mx.aol.com (v124.15) with ESMTP id MAILCIAMA084-928f4a54885590; Wed, 08 Jul 2009 07:51:50 -0400 X-Original-Date: Wed, 8 Jul 2009 05:51:45 -0600 From: mikeeasley Subject: Re: [LML] Nose Shimmy Theory X-Original-To: "Lancair Mailing List" In-Reply-To: X-Original-Message-ID: References: X-Mailer: Nexus Desktop Client 3.1.20.1 MIME-Version: 1.0 Content-Type: MULTIPART/alternative; BOUNDARY=481efabe-0b9e-4176-8984-97110d937506 Content-Transfer-Encoding: 8bit X-AOL-IP: 76.25.136.43 X-Spam-Flag:NO --481efabe-0b9e-4176-8984-97110d937506 Content-Type: TEXT/plain; charset=us-ascii Fred, When I tested the 5606 hydraulic fluid it took 19.5 seconds to drain the Zahn cup at 55F. It took 18 seconds at 180F. I'm not sure exactly how that relates to damping, but that's only a 8% loss of viscosity over 125F range. I tested a bunch of oils including some thicker transmission oil and Mobil 1 and Castrol Synthetic. It appears from my testing that the "multi-viscosity" oils don't behave much different than the single weight oils at higher temperatures, but the additives help reduce viscosity at low temperatures. In our normal operating temperature range, the difference in the temperature characteristics between the expensive multi-viscosity oils and good ol' 30W was minimal. Living in Colorado, there were times when I pulled my plane out of a very cold hangar, ~30F, and could feel how stiff the old strut was. After flying to Las Vegas, for example, it was much easier to turn with the tow bar. I don't have any of that variation with the new strut. Mike Easley Colorado Springs ES --481efabe-0b9e-4176-8984-97110d937506 Content-Type: TEXT/html; charset=utf-8 Content-Transfer-Encoding: 8BIT
Fred,
 
When I tested the 5606 hydraulic fluid it took 19.5 seconds to drain the Zahn cup at 55F.  It took 18 seconds at 180F.  I'm not sure exactly how that relates to damping, but that's only a 8% loss of viscosity over 125F range.
 
I tested a bunch of oils including some thicker transmission oil and Mobil 1 and Castrol Synthetic.  It appears from my testing that the "multi-viscosity" oils don't behave much different than the single weight oils at higher temperatures, but the additives help reduce viscosity at low temperatures.  In our normal operating temperature range, the difference in the temperature characteristics between the expensive multi-viscosity oils and good ol' 30W was minimal.
 
Living in Colorado, there were times when I pulled my plane out of a very cold hangar, ~30F, and could feel how stiff the old strut was.  After flying to Las Vegas, for example, it was much easier to turn with the tow bar.  I don't have any of that variation with the new strut.
 
Mike Easley
Colorado Springs
ES
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