X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Sun, 27 Feb 2011 16:09:13 -0500 Message-ID: X-Original-Return-Path: Received: from hrndva-omtalb.mail.rr.com ([71.74.56.123] verified) by logan.com (CommuniGate Pro SMTP 5.4c2o) with ESMTP id 4882655 for lml@lancaironline.net; Fri, 25 Feb 2011 12:53:29 -0500 Received-SPF: none receiver=logan.com; client-ip=71.74.56.123; envelope-from=Wolfgang@MiCom.net X-Original-Return-Path: X-Authority-Analysis: v=1.1 cv=+c36koQ5Dcj/1qolKHjtkYAGXvrVJRRiKMp+84F5sLg= c=1 sm=0 a=MHZY6FYWMEQOp7S43i2QIw==:17 a=3oc9M9_CAAAA:8 a=Ia-xEzejAAAA:8 a=x2ruqFfzAAAA:8 a=CjxXgO3LAAAA:8 a=pcLIrrrKAAAA:8 a=AAvYLDLOAAAA:8 a=xM5mUL_kKCNSg6dCgxUA:9 a=mefO49iTFRCwK4JQ0jEA:7 a=LiVtHBDstAFLESzESOCnExc2y24A:4 a=wPNLvfGTeEIA:10 a=l0LJEUmbi04A:10 a=vNaDsT68qR4A:10 a=U8Ie8EnqySEA:10 a=EzXvWhQp4_cA:10 a=rC2wZJ5BpNYA:10 a=ftFGBYpk1mUA:10 a=s2loLT2QvaoA:10 a=KtBScauWuhmB0HDD:21 a=KalehZy1wia092q6:21 a=gtqJ9yqd5MnNPbqEZc4A:9 a=x0k2TlYzMLYDKPpV0bMA:7 a=89lcd9wyE2bZ0VdDcZpxeEhaGYsA:4 a=MHZY6FYWMEQOp7S43i2QIw==:117 X-Cloudmark-Score: 0 X-Originating-IP: 74.218.201.50 Received: from [74.218.201.50] ([74.218.201.50:1762] helo=Lobo) by hrndva-oedge03.mail.rr.com (envelope-from ) (ecelerity 2.2.3.46 r()) with ESMTP id 99/48-24070-57CE76D4; Fri, 25 Feb 2011 17:52:54 +0000 X-Original-Message-ID: <000901cbd514$cf86a0c0$6401a8c0@Lobo> From: "Wolfgang" X-Original-To: Subject: Re: [LML] Re: prop balance X-Original-Date: Fri, 25 Feb 2011 12:52:46 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0006_01CBD4EA.E6751660" 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_0006_01CBD4EA.E6751660 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable It's interesting to note that the percentage peak torque from multiple = cylinder motors is about equal to the percentage peak of a single = cylinder motor divided by the number of cylinders. The absolute torque = peak from the individual cylinders being a function of the cylinder = size. Wolfgang From: Sky2high@aol.com=20 Sender: =20 Subject: Re: [LML] Re: prop balance=20 Date: Thu, 24 Feb 2011 11:08:18 -0500=20 To: lml@lancaironline.net=20 =20 =20 Slava, Read this to get an idea of the instantaneous torque the prop = sees through its full revolution: = http://www.epi-eng.com/piston_engine_technology/torsional_excitation_from= _piston_engines.htm Many engines may have dampers to reduce power pulse effects from = the drive shaft. The one we are discussing here is specifically = designed to be mounted on a Lycoming starter ring. The following text = was copied from the appropriate ad in the May 2010 Sport Aviation = Magazine: Mark Landoll, 405-392-3847, landollskydoll2001@yahoo.com Grayhawk AKA Scott Krueger PS I have been flying with this contraption on my Lyc I/O 320 for = more than 12 years. In a message dated 2/23/2011 8:11:01 A.M. Central Standard Time, = slavaharlamor@sbcglobal.net writes: 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_0006_01CBD4EA.E6751660 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
It's interesting to note that the = percentage peak=20 torque from multiple cylinder motors is about equal to the percentage = peak of a=20 single cylinder motor divided by the number of cylinders. The absolute = torque=20 peak from the individual cylinders being a function of the cylinder=20 size.
 
Wolfgang
 
lml@lancaironline.net
From: Sky2high@aol.com
Sender: <marv@lancaironline.net>
Subject: Re: [LML] Re: prop = balance
Date: Thu, 24 Feb 2011 11:08:18 = -0500
To:
Slava,
 
Read this to  get an idea of the instantaneous torque = the prop=20 sees through its full revolution:
 
http://www.epi-eng.com/piston_engine_technology/torsional_= excitation_from_piston_engines.htm
 
Many engines may have dampers to reduce power pulse effects = from the=20 drive shaft.  The one we are discussing here is specifically = designed=20 to be mounted on a Lycoming starter ring.  The following = text  was copied from the appropriate ad in = the May=20 2010 Sport Aviation Magazine:
 
Mark Landoll, 405-392-3847, landollskydoll2001@yahoo.com
 
Grayhawk AKA Scott Krueger
PS I have been flying with this contraption on my = Lyc I/O 320=20 for more than 12 years.
 
In a message dated 2/23/2011 8:11:01 A.M. Central Standard = Time,=20 slavaharlamor@sbcglobal.net writes:
Hello All, I have been in the background studying for = my=20 build project. Grayhawk, your information about the = harmonic=20 damper is an educational point of significance. I know = nothing=20 about dampers, is there a book that I can get to learn = about this=20 subject. Does a damper have to be specific to an engine or = is the=20 design universal 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=20 21, 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=20 or 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=20 difficult to measure the effect.  Another benefit = is to=20 move the CG forward - usually a plus in the 320/360 = series=20 aircraft.
 
The person in Redmond is wrong.  He is = misinformed=20 about the purpose of the damper.
 
I have such a damper and I do balance my = prop. =20 Because I am in a partnership that owns a = simple=20 balance device, I have no constraint on performing a = balance or=20 just checking the last balance to insure it has not = changed (it=20 has not).
 
Go balance that prop.  Weights/longer = bolts can=20 be affixed where the damper is mounted to the starter=20 ring.  However, be careful that any large area = washers not stick out far enough to come in contact = with=20 the cowling in 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=20 the starter ring gear.
It is supposed to balance = the engine=20 with its internal weights that are supposed to arrange = themselves to cancel or dampen our any sensed=20 vibrations.
The "balancer" is about 2 inches in = debth and=20 almost the diameter of the ring gear; it is all self = contained=20 and you would have to take the prop off to get it off = and take=20 it apart if one was at least currious what was inside = of=20 it.
 
It's difficult to know if a 4 = cyclynder=20 Lycoming is as smooth as it can be, because it's not a = real=20 smooth engine under the best of = conditions.
 
I=20 inquired to a local experienced prop balance person in = Redmond=20 and they concluded that because of the dynamic = balancer on the=20 ring gear, he would not attempt to balance the engine = with his=20 expensive balance work, as he thought the attached = dynamic=20 balancer would change the internal weight at=20 will.
 
Does anyone have any experience = with these=20 dynamic balancers attached to the ring=20 gear???
 
Cheers
 
Jack = Addison =20 N360JS
near Redmond,=20 = OR
=3D
=
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