X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Thu, 24 Feb 2011 11:09:41 -0500 Message-ID: X-Original-Return-Path: Received: from hrndva-omtalb.mail.rr.com ([71.74.56.122] verified) by logan.com (CommuniGate Pro SMTP 5.4c2o) with ESMTP id 4880142 for lml@lancaironline.net; Wed, 23 Feb 2011 13:15:15 -0500 Received-SPF: none receiver=logan.com; client-ip=71.74.56.122; envelope-from=Wolfgang@MiCom.net X-Original-Return-Path: X-Authority-Analysis: v=1.1 cv=dquaJDitHqzHCdqWSoZ6IgapSuTzW/4TaRYx9N9k4W8= c=1 sm=0 a=MHZY6FYWMEQOp7S43i2QIw==:17 a=pcLIrrrKAAAA:8 a=Ia-xEzejAAAA:8 a=3oc9M9_CAAAA:8 a=AAvYLDLOAAAA:8 a=xM5mUL_kKCNSg6dCgxUA:9 a=GwNsw_om238Zyrui3mUA:7 a=mFcF440okg2LLxuwuJu5xo9oPckA:4 a=wPNLvfGTeEIA:10 a=ftFGBYpk1mUA:10 a=EzXvWhQp4_cA:10 a=U8Ie8EnqySEA:10 a=s2loLT2QvaoA:10 a=SGaiH8sP7PKd0_IxdugA:9 a=AK6wq1FQJ8fnLWsRsTkA:7 a=Tvq2_6BCxYWdgu3SBvzVqJjqdOoA:4 a=MHZY6FYWMEQOp7S43i2QIw==:117 X-Cloudmark-Score: 0 X-Originating-IP: 74.218.201.50 Received: from [74.218.201.50] ([74.218.201.50:2458] helo=Lobo) by hrndva-oedge01.mail.rr.com (envelope-from ) (ecelerity 2.2.3.46 r()) with ESMTP id 76/4D-14011-29E456D4; Wed, 23 Feb 2011 18:14:42 +0000 X-Original-Message-ID: <000b01cbd385$87ca8a20$6401a8c0@Lobo> From: "Wolfgang" X-Original-To: Subject: Re: [LML] Re: prop balance X-Original-Date: Wed, 23 Feb 2011 13:14:36 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0008_01CBD35B.9EC97A80" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.2180 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 This is a multi-part message in MIME format. ------=_NextPart_000_0008_01CBD35B.9EC97A80 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable It's called a HARMONIC damper. That's because it is intended to dampen = HARMONIC induced TORSIONAL vibrations in the crank shaft. The offending = harmonics are induced by the power stroke of the pistons and can induce = torsional vibrations in the crank shaft which can cause the crank to = break. Six cylinder engines have a longer crank shaft and are more prone = to this problem than four cylinder engines. Pre-ignition can severely = aggravate this problem. Wolfgang From: SLAVA HARLAMOR =20 Sender: =20 Subject: Re: [LML] Re: prop balance=20 Date: Wed, 23 Feb 2011 09:09:33 -0500=20 To: lml@lancaironline.net=20 =20 =20 Hello All, I have been in the background studying for my = build project. Grayhawk, your information about the harmonic damper is = an educational point of significance. I know nothing about dampers, is = there a book that I can get to learn about this subject. Does a damper = have to be specific to an engine or is the design universal to any = recip? Thank you for any advice in advance, Sincerely, Mr. Slava Harlamor slavaharlamor@sbcglobal.net=20 --- On Mon, 2/21/11, Sky2high@aol.com = wrote: From: Sky2high@aol.com Subject: [LML] Re: prop balance To: lml@lancaironline.net Date: Monday, February 21, 2011, 10:32 AM Jack, The 12 pound harmonic damper is present to reduce negative = torque between power strokes. It has a steel ring suspended in = silicone. It does not help balance the prop - it should be totally = neutral with respect to balance but not circular momentum. On = fixed-pitch prop (likely wooden or composite) driven engines, there is = often a 100 rpm increase because of added momentum and a reduction in = the negative torque by damping it. Constant speed prop users may find = it difficult to measure the effect. Another benefit is to move the CG = forward - usually a plus in the 320/360 series aircraft. The person in Redmond is wrong. He is misinformed about = the purpose of the damper. I have such a damper and I do balance my prop. Because I = am in a partnership that owns a simple balance device, I have no = constraint on performing a balance or just checking the last balance to = insure it has not changed (it has not). Go balance that prop. Weights/longer bolts can be affixed = where the damper is mounted to the starter ring. However, be careful = that any large area washers not stick out far enough to come in contact = with the cowling in dramatic + or - G maneuvers. Geeeeze! Grayhawk In a message dated 2/21/2011 7:26:04 A.M. Central Standard = Time, jraddison@msn.com writes: Question? On my LNC2-360 (BIB plus high comp pistons) there is an = add-on "balancer" bolted to the face of the starter ring gear. It is supposed to balance the engine with its internal = weights that are supposed to arrange themselves to cancel or dampen our = any sensed vibrations. The "balancer" is about 2 inches in debth and almost the = diameter of the ring gear; it is all self contained and you would have = to take the prop off to get it off and take it apart if one was at least = currious what was inside of it. =20 It's difficult to know if a 4 cyclynder Lycoming is as = smooth as it can be, because it's not a real smooth engine under the = best of conditions. =20 I inquired to a local experienced prop balance person in = Redmond and they concluded that because of the dynamic balancer on the = ring gear, he would not attempt to balance the engine with his expensive = balance work, as he thought the attached dynamic balancer would change = the internal weight at will. =20 Does anyone have any experience with these dynamic = balancers attached to the ring gear??? =20 Cheers =20 Jack Addison N360JS near Redmond, OR =3D=20 =20 ------=_NextPart_000_0008_01CBD35B.9EC97A80 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
It's called a HARMONIC damper. That's = because it is=20 intended to dampen HARMONIC induced TORSIONAL vibrations in the = crank=20 shaft. The offending harmonics are induced by the power stroke of the = pistons=20 and can induce torsional vibrations in the crank shaft which can cause = the crank=20 to break. Six cylinder engines have a longer crank shaft and are = more prone=20 to this problem than four cylinder engines. Pre-ignition can = severely=20 aggravate this problem.
 
Wolfgang
 
lml@lancaironline.net
From: SLAVA HARLAMOR=20 <slavaharlamor@sbcglobal.net>
Sender: <marv@lancaironline.net>
Subject: Re: [LML] Re: prop = balance
Date: Wed, 23 Feb 2011 09:09:33 = -0500
To:
Hello All, I have been in the background studying for = my build=20 project. Grayhawk, your information about the harmonic = damper is an=20 educational point of significance. I know nothing about = dampers, is=20 there a book that I can get to learn about this subject. = Does a=20 damper have to be specific to an engine or is the design = universal=20 to any recip?
 
Thank you for any advice in advance,
 
Sincerely,
 
Mr. Slava Harlamor
 


--- On Mon, 2/21/11, Sky2high@aol.com=20 <Sky2high@aol.com> wrote:

From: Sky2high@aol.com=20 <Sky2high@aol.com>
Subject: [LML] = Re: prop=20 balance
To: lml@lancaironline.net
Date: Monday, = February 21,=20 2011, 10:32 AM

Jack,
 
The 12 pound harmonic damper is present to = reduce=20 negative torque between power strokes.  It has a = steel ring=20 suspended in silicone.  It does not help balance = the=20 prop - it should be totally neutral with respect to = balance but=20 not circular momentum.  On fixed-pitch prop (likely = wooden or=20 composite) driven engines, there is often a 100 rpm = increase=20 because of added momentum and a reduction in the negative = torque=20 by damping it.  Constant speed prop users may find it = difficult to measure the effect.  Another benefit is = to move=20 the CG forward - usually a plus in the 320/360 series=20 aircraft.
 
The person in Redmond is wrong.  He is = misinformed about=20 the purpose of the damper.
 
I have such a damper and I do balance my prop.  = Because=20 I am in a partnership that owns a simple = balance=20 device, I have no constraint on performing a balance or = just=20 checking the last balance to insure it has not changed (it = has=20 not).
 
Go balance that prop.  Weights/longer bolts = can be=20 affixed where the damper is mounted to the starter = ring. =20 However, be careful that any large area = washers not=20 stick out far enough to come in contact with the cowling = in=20 dramatic + or - G maneuvers.
 
Geeeeze!
 
Grayhawk
 
In a message dated 2/21/2011 7:26:04 A.M. Central = Standard=20 Time, jraddison@msn.com writes:
Question?
On my LNC2-360 (BIB plus high = comp=20 pistons) there is an add-on "balancer" bolted to the = face of the=20 starter ring gear.
It is supposed to balance the = engine with=20 its internal weights that are supposed to arrange = themselves to=20 cancel or dampen our any sensed vibrations.
The = "balancer" is=20 about 2 inches in debth and almost the diameter of the = ring=20 gear; it is all self contained and you would have to = take the=20 prop off to get it off and take it apart if one was at = least=20 currious what was inside of it.
 
It's = difficult to=20 know if a 4 cyclynder Lycoming is as smooth as it can = be,=20 because it's not a real smooth engine under the best of=20 conditions.
 
I inquired to a local = experienced prop=20 balance person in Redmond and they concluded that = because of the=20 dynamic balancer on the ring gear, he would not attempt = to=20 balance the engine with his expensive balance work, as = he=20 thought the attached dynamic balancer would change the = internal=20 weight at will.
 
Does anyone have any = experience=20 with these dynamic balancers attached to the ring=20 gear???
 
Cheers
 
Jack = Addison =20 N360JS
near Redmond,=20 = OR
=3D
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