X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Sun, 04 Aug 2013 17:38:26 -0400 Message-ID: X-Original-Return-Path: Received: from nm11-vm6.bullet.mail.ne1.yahoo.com ([98.138.91.104] verified) by logan.com (CommuniGate Pro SMTP 6.0.5) with ESMTPS id 6402654 for lml@lancaironline.net; Sat, 03 Aug 2013 19:45:56 -0400 Received-SPF: none receiver=logan.com; client-ip=98.138.91.104; envelope-from=mcmess1919@yahoo.com Received: from [98.138.101.131] by nm11.bullet.mail.ne1.yahoo.com with NNFMP; 03 Aug 2013 23:45:21 -0000 Received: from [98.138.84.46] by tm19.bullet.mail.ne1.yahoo.com with NNFMP; 03 Aug 2013 23:45:21 -0000 Received: from [127.0.0.1] by smtp114.mail.ne1.yahoo.com with NNFMP; 03 Aug 2013 23:45:21 -0000 X-Yahoo-Newman-Id: 828717.28607.bm@smtp114.mail.ne1.yahoo.com X-Yahoo-Newman-Property: ymail-3 X-YMail-OSG: xg96q1sVM1m41qWDG6jMbAyMHyFOJ5W8.nElNBfY47lFmpO B.orZuV0RQrKTbv7E4S4X7FlJQCMsrKp9NleFmw8fejsiXp4QIlb8AWaJQ6v A..YcO_9uKk.JDadOU_FDKOrtkLwr4T9_y9oY0PhTTb0EkCD8HQBcbxmaN_I SBOip8jYn_IlzkAcWmXTzHaKxTTU4TQO5qD72m7Hjc5xouYERtErOmIFvwMf hZMRNlhq3nsrApuN8KFjQdZSNK7l.9EBASMwEN3NOeHWHA52MNuJDhAoK6M4 2fFo9Z_RbRyQj1DHi7CmQc5Whl7fFdTdic0xUoSDIhJkWgOCM8SjvYGBgwrl 1twuOtT5g5HNABdmO9C_OmTh6dvYe1gXDd0OfdX7xiRPKwfBUuhHENCyXd8I LqPFt0MC9brqcA6g85_uKHCj1RxY8R1BINF2_jUPQ3QSnyImPytzzdNDDZ88 S.BD.8RP3IkTLq7gREVXCrCfmGUhGzviZk186RBuGbVTVxA1ZWW0GWdYOHsV e63u6eHpC8neg038km6aewR.kTQ.n3tFEEDpZb_epvOrKIjQYPAWMeMZhNOs - X-Yahoo-SMTP: rK4i7HqswBC7mDE8.sOiWQeO4CeReXc- X-Rocket-Received: from StevePC (mcmess1919@67.187.169.184 with ) by smtp114.mail.ne1.yahoo.com with SMTP; 03 Aug 2013 16:45:21 -0700 PDT From: "Steve Colwell" X-Original-To: "'Lancair Mailing List'" References: In-Reply-To: Subject: Potential Problem-Engine Vibration X-Original-Date: Sat, 3 Aug 2013 16:45:20 -0700 X-Original-Message-ID: <00f301ce90a3$84b24e30$8e16ea90$@com> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_00F4_01CE9068.D8537630" X-Mailer: Microsoft Office Outlook 12.0 thread-index: Ac6MkKTlkrE4LpC3Sdip9lTvg2dAFAEA4Y9g Content-Language: en-us This is a multi-part message in MIME format. ------=_NextPart_000_00F4_01CE9068.D8537630 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Oshkosh/Vibration, or what I learned on my summer vacation: First, all 550 Continental crankshaft separations and cracks have been traced to prop strikes or likely prop strikes. We are back on flight status with 15SC. Les Doud (Applications Engineer) of Hartzell, spoke at Jeff Edwards Forum and spent 30+ minutes with me later discussing our Vibrations. The most interesting point was the weight of a metal 3 blade prop causes it to act as a gyroscope. The engine and all moving parts can create a harmonic more easily as a result. Lighter weight composite props have much less gyro effect and therefore are inherently smoother. Our stiff composite airframes are more susceptible than an aluminum one with "every rivet acting as a damper". I previously thought the main reason was composite blades had less resonance than metal. After all the obvious sources have been checked and fixed, the best diagnosis tool is a in flight Spectrum Analysis and Plot with the top of the line DynaVibe (tool cost $3000+). At least that is what the DynaVibe rep. said in a forum and Les agreed. Mount the sensor tightly on something solid like a spar cap, horizontal and parallel to the spar (not on anything like the panel dust cover). Determining increased first, second or third order vibrations narrows down the source. Les thought in my case of unpredictable vibration, the free iPhone ap "Vibration" could be accurate enough to find the major shake. Les advised checking prop orientation for parallel alignment of one of the blades with #6 cylinder at Top Dead Center on compression. This is best for smoothness. Paul Snyder, an Engineer with Lord Mounts, thinks he may be able to help. He cited the Mooney Ovation with a vibration problem that was improved by a single stiffer mount on the left front. Early Cirrus with 550's and 3 blade Hartzell's vibrated, later versions have 6 mounts with 4 near the front to better balance the static weight of the prop and engine. He may have suggestions when he knows the part number of the brown (silicone) mounts supplied to me by Lancair. Oshkosh is a excellent resource for all things aviation. You can button hole the engineer/designer/owner and get a lot closer to answers. I was impressed with their willingness to help us and the lack of defensiveness on their part. Oh yeah, the weather, just about perfect, in the 70's most of the time. The LOBO/Lancair Banquet was great with a full house, Alberto's Mars Curiosity talk was amazing and the new location at Best Western Waterfront Hotel is a big improvement in banquet room and food/service quality. You shoudda been there! Steve Colwell aka "Claudette's husband" ------=_NextPart_000_00F4_01CE9068.D8537630 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

 

Oshkosh/Vibration, or what I learned on my summer = vacation:

 

First, all 550 Continental crankshaft separations and cracks have been = traced to prop strikes or likely prop strikes.  We are back on = flight status with 15SC.   

 

Les Doud (Applications Engineer) of Hartzell, spoke at Jeff Edwards = Forum and spent 30+ minutes with me later discussing our = Vibrations.  The most interesting point was the weight of a metal 3 = blade prop causes it to act as a gyroscope.  The engine and all = moving parts can create a harmonic more easily as a result.  = Lighter weight composite props have much less gyro effect and therefore = are inherently smoother.  Our stiff composite airframes are more = susceptible than an aluminum one with “every rivet acting as a = damper”.  I previously thought the main reason was composite = blades had less resonance than metal.

 

After all the obvious sources have been checked and fixed, the best = diagnosis tool is a in flight Spectrum Analysis and Plot with the top of = the line DynaVibe (tool cost $3000+).  At least that is what the = DynaVibe rep. said in a forum and Les agreed.  Mount the sensor = tightly on something solid like a spar cap, horizontal and parallel to = the spar (not on anything like the panel dust cover).  Determining = increased first, second or third order vibrations narrows down the = source.  Les thought in my case of unpredictable vibration, the = free iPhone ap “Vibration” could be accurate enough to find = the major shake. 

 

Les advised checking prop orientation for parallel alignment of one of = the blades with #6 cylinder at Top Dead Center on compression. =  This is best for smoothness.

 

Paul Snyder, an Engineer with Lord Mounts, thinks he may be able to = help.  He cited the Mooney Ovation with a vibration problem that = was improved by a single stiffer mount on the left front.  Early = Cirrus with 550’s and 3 blade Hartzell’s vibrated, later = versions have 6 mounts with 4 near the front to better balance the = static weight of the prop and engine.  He may have suggestions when = he knows the part number of the brown (silicone) mounts supplied to me = by Lancair.

 

Oshkosh is a excellent resource for all things aviation.  You can = button hole the engineer/designer/owner and get a lot closer to = answers.  I was impressed with their willingness to help us and the = lack of defensiveness on their part.  

 

Oh yeah, the weather, just about perfect, in the 70’s most of = the time.  The LOBO/Lancair Banquet was great with a full house, = Alberto’s Mars Curiosity talk was amazing and the new location at = Best Western Waterfront Hotel is a big improvement in banquet room and = food/service quality.  You shoudda been = there!

 

Steve Colwell  aka “Claudette’s = husband”

 

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