X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from fmailhost04.isp.att.net ([204.127.217.104] verified) by logan.com (CommuniGate Pro SMTP 5.2c1) with ESMTP id 2551500 for flyrotary@lancaironline.net; Sun, 02 Dec 2007 00:36:20 -0500 Received-SPF: none receiver=logan.com; client-ip=204.127.217.104; envelope-from=rusty@radrotary.com Received: from rad (adsl-065-006-194-009.sip.pns.bellsouth.net[65.6.194.9]) by isp.att.net (frfwmhc04) with SMTP id <20071202053541H0400a37fne>; Sun, 2 Dec 2007 05:35:42 +0000 X-Originating-IP: [65.6.194.9] From: "Russell Duffy" To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] Re: Giving up on single rotor Date: Sat, 1 Dec 2007 23:34:01 -0600 Message-ID: <000501c834a4$f27b0ad0$6c01a8c0@rad> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0006_01C83472.A7E09AD0" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.6822 Importance: Normal Thread-Index: Acg0gmG5gQJrEBQwRAqFQDEol5jijQAIVRVA In-Reply-To: X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3198 This is a multi-part message in MIME format. ------=_NextPart_000_0006_01C83472.A7E09AD0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable So what durometer is your gut feeling now that you went this far?=20 =20 Hi George, =20 I don't think you can compare the durometer of one damper to another, because the physical size is as important as the hardness of the rubber. The Autoflight drive uses a stock Centaflex coupler that's only = available in 50 and 60 durometer. It's a fairly large diameter, and thick coupler. = 50 was better than 60, but two 50's (effectively 25) in series was way too soft. Maybe a 40 would be good, but it doesn't exist. =20 =20 Richard seems to be having better luck with the Hirth drive. Two = strokes are rough at low rpms, so perhaps they already have the right damper for = the job. I also suspect his engine has softer power pulses at low rpms. = It's a 12A for one, and PP for another. PP is great at high rpms, but not know = for good power down low. It's the best theory I have. =20 =20 Cheers, Rusty =20 ------=_NextPart_000_0006_01C83472.A7E09AD0 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Message
So what durometer is your gut = feeling now=20 that you went this far? 
 
Hi George,
 
I don't think you can compare the durometer of = one damper=20 to another, because the physical size is as important as the hardness of = the=20 rubber.  The Autoflight drive uses a stock Centaflex coupler that's = only=20 available in 50 and 60 durometer.  It's a fairly large diameter, = and thick=20 coupler.  50 was better than 60, but two 50's (effectively 25) in = series=20 was way too soft.  Maybe a 40 would be good, but it doesn't=20 exist.  
 
Richard seems to be having better luck = with=20 the Hirth drive.  Two strokes are rough at low rpms, so = perhaps they=20 already have the right damper for the job.  I also suspect his = engine=20 has softer power pulses at low rpms.  It's a 12A for one, and PP = for=20 another.  PP is great at high rpms, but not know for good power = down=20 low.  It's the best theory I=20 have.  
 
Cheers,
Rusty=20  
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