X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from fed1rmmtao104.cox.net ([68.230.241.42] verified) by logan.com (CommuniGate Pro SMTP 5.3.4) with ESMTP id 4178606 for flyrotary@lancaironline.net; Thu, 25 Mar 2010 14:11:38 -0400 Received-SPF: none receiver=logan.com; client-ip=68.230.241.42; envelope-from=alventures@cox.net Received: from fed1rmimpo01.cox.net ([70.169.32.71]) by fed1rmmtao104.cox.net (InterMail vM.8.00.01.00 201-2244-105-20090324) with ESMTP id <20100325181103.LWUZ29534.fed1rmmtao104.cox.net@fed1rmimpo01.cox.net> for ; Thu, 25 Mar 2010 14:11:03 -0400 Received: from BigAl ([72.192.128.205]) by fed1rmimpo01.cox.net with bizsmtp id xWB31d00K4S1t5C03WB32L; Thu, 25 Mar 2010 14:11:03 -0400 X-VR-Score: 0.00 X-Authority-Analysis: v=1.1 cv=9X1BeRvGVdXikaVgI7mHUqmIOlosh/BCISq12UegNM8= c=1 sm=1 a=OsWrPOa0hZUA:10 a=Vegc0WxVmH5BHtpNDyThtA==:17 a=KUeafc-gGRUt0L1gXFgA:9 a=bsglajD6hHmJSXP9XGVyfTyevGEA:4 a=CjuIK1q_8ugA:10 a=uD-gjTWAJsDaEks2XmoA:9 a=AtTrqxx9x7nokc0SxcgA:7 a=NzRxsz5PyeSQTse-2yf3H7NGrbkA:4 a=Vegc0WxVmH5BHtpNDyThtA==:117 X-CM-Score: 0.00 From: "Al Gietzen" To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] Re: Adaptor plate rivets Date: Thu, 25 Mar 2010 11:10:53 -0800 Message-ID: <09D27863733E4331890EDA1DF16F89C7@BigAl> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0022_01CACC0B.D593F2F0" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.6856 Importance: Normal In-Reply-To: Thread-Index: AcrMP3WCiMomVq1FRgm0XF7GXx7HngADIs0g X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.5579 This is a multi-part message in MIME format. ------=_NextPart_000_0022_01CACC0B.D593F2F0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable BTW, did you have visible smoke trails? I don't. I wonder if there was some sort of change in the way the riveting was done. =20 Dave; =20 There were maybe a couple very slight trails on the flange side (toward = the re-drive). On the other side (I guess the head side of the rivets) = where I could only see about 4-5 of them through the holes in the flywheel (ring gear); all had distinct dark trails. =20 It's possible that power is the main issue (average torque), but it = seems to me that peak torque and torque variation amplitude are what are going to matter most. You and Mark are going to have lower peak torque than = those of us with turbo engines, and with 20B's you are are going to have lower = torque amplitude than even those with n.a. 13B's. =20 One would think that is true; but you can't be sure. It is possible the = 20B may have some harmonics (resonance vibration) somewhere in the range of operation that the 13B doesn't have. Seems unlikely with the snubbers = and the 'play' in the system, but . . . We need more feedback from all the users with more than 150 hours, or so, to see what the pattern is. I'm = not aware of rivet changes - Tracy? Mark and I both have constant speed props and I think Al does also. = Don't see how it could make any difference but worth considering in the investigation. Bobby I have a fixed pitch Catto. The mass of the prop would likely be a = factor - if there is some torsional vibration involved. My Catto only weighs = about 16 lbs; plus 3-4 for the extension and spinner. I have 180 hours and = barely detectable rivet wear; Mark apparently has more wear at about 150. Al =20 ------=_NextPart_000_0022_01CACC0B.D593F2F0 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

BTW, did you have visible smoke trails?  = I don't.  I wonder if there was some sort of change in the way the = riveting was done. 

Dave;

 

There were maybe a couple very = slight trails on the flange side (toward the re-drive).  On the other side = (I guess the head side of the rivets) where I could only see about 4-5 of = them through the holes in the flywheel (ring gear); all had distinct dark = trails.

 

It's possible that power is the main issue (average torque), but it seems to = me that peak torque and torque variation amplitude are what are = going to matter most.  You and Mark are going to have lower peak torque than = those of us with turbo engines, and with 20B's you are are going to have lower = torque amplitude than even those with n.a. 13B's. 

One would think that is true; but you can’t be sure.  It is = possible the 20B may have some harmonics (resonance vibration) somewhere in the range = of operation that the 13B doesn’t have. Seems unlikely with the = snubbers and the ‘play’ in the system, but . . .  We need more = feedback from all the users with more than 150 hours, or so, to see what the = pattern is.  I’m not aware of rivet changes – Tracy?=

Mark and I both have constant speed props and I think Al does also. Don't see how = it could make any difference but worth considering in the = investigation.  Bobby

I have a fixed pitch Catto.  The mass of the prop would likely be a = factor – if there is some = torsional vibration involved.  My Catto only weighs about 16 lbs; plus 3-4 = for the extension and spinner. I have 180 hours and barely detectable rivet = wear; Mark apparently has more wear at about 150.

Al

 

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