X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Thu, 24 Feb 2011 11:08:18 -0500 Message-ID: X-Original-Return-Path: Received: from imr-ma03.mx.aol.com ([64.12.206.41] verified) by logan.com (CommuniGate Pro SMTP 5.4c2o) with ESMTP id 4879934 for lml@lancaironline.net; Wed, 23 Feb 2011 10:15:35 -0500 Received-SPF: pass receiver=logan.com; client-ip=64.12.206.41; envelope-from=Sky2high@aol.com Received: from imo-da02.mx.aol.com (imo-da02.mx.aol.com [205.188.169.200]) by imr-ma03.mx.aol.com (8.14.1/8.14.1) with ESMTP id p1NFEofv008635 for ; Wed, 23 Feb 2011 10:14:50 -0500 Received: from Sky2high@aol.com by imo-da02.mx.aol.com (mail_out_v42.9.) id q.cab.6a75122e (34980) for ; Wed, 23 Feb 2011 10:14:47 -0500 (EST) Received: from magic-m16.mail.aol.com (magic-m16.mail.aol.com [172.21.188.208]) by cia-da08.mx.aol.com (v129.9) with ESMTP id MAILCIADA085-88a44d652466334; Wed, 23 Feb 2011 10:14:46 -0500 From: Sky2high@aol.com X-Original-Message-ID: <136f7e.238cb2c5.3a967e66@aol.com> X-Original-Date: Wed, 23 Feb 2011 10:14:46 EST Subject: Re: [LML] Re: prop balance X-Original-To: lml@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="part1_136f7e.238cb2c5.3a967e66_boundary" X-Mailer: AOL 9.6 sub 130 X-AOL-IP: 24.15.17.119 X-Spam-Flag:NO X-AOL-SENDER: Sky2high@aol.com --part1_136f7e.238cb2c5.3a967e66_boundary Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit 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_p iston_engines.htm_ (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_ (mailto: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_ (mailto:slavaharlamor@sbcglobal.net) --- 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. 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. 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. Does anyone have any experience with these dynamic balancers attached to the ring gear??? Cheers Jack Addison N360JS near Redmond, OR = --part1_136f7e.238cb2c5.3a967e66_boundary Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable
Slava,
 
Read this to  get an idea of the instantaneous torque the prop= sees=20 through its full revolution:
 
 
Many engines may have dampers to reduce power pulse effects from the= drive=20 shaft.  The one we are discussing here is specifically designed to be= =20 mounted on a Lycoming starter ring.  The following text &nb= sp;was=20 copied from the appropriate ad in the May 2010 Sport Aviation=20 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 fo= r more=20 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 buil= d=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 da= mper=20 have to be specific to an engine or is the design universal to any= =20 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:=20 Sky2high@aol.com <Sky2high@aol.com>
Subject:=20 [LML] Re: prop balance
To:=20 lml@lancaironline.net
Date: Monday, February 21, 2011, 10:32= =20 AM

Jack,
 
The 12 pound harmonic damper is present to reduce nega= tive=20 torque between power strokes.  It has a steel ring suspende= d in=20 silicone.  It does not help balance the prop - it shou= ld be=20 totally neutral with respect to balance but not circular=20 momentum.  On fixed-pitch prop (likely wooden or composite)= =20 driven engines, there is often a 100 rpm increase because of add= ed=20 momentum and a reduction in the negative torque by damping it.&n= bsp;=20 Constant speed prop users may find it difficult to measure the= =20 effect.  Another benefit is to move the CG forward - usuall= y a=20 plus in the 320/360 series aircraft.
 
The person in Redmond is wrong.  He is misinformed abo= ut the=20 purpose of the damper.
 
I have such a damper and I do balance my prop.  Becaus= e I am=20 in a partnership that owns a simple balance devic= e, I=20 have no constraint on performing a balance or just checking the= last=20 balance to insure it has not changed (it has 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 st= ick=20 out far enough to come in contact with the cowling in dramatic= + or -=20 G maneuvers.
 
Geeeeze!
 
Grayhawk
 
In a message dated 2/21/2011 7:26:04 A.M. Central Standard= Time,=20 jraddison@msn.com writes:
Que= stion?
On my LNC2-360 (BIB plus high comp pistons)=20 there is an add-on "balancer" bolted to the face of the starte= r ring=20 gear.
It is supposed to balance the engine with its interna= l=20 weights that are supposed to arrange themselves to cancel or= dampen=20 our any sensed vibrations.
The "balancer" is about 2 inches= in=20 debth and almost the diameter of the ring gear; it is all self= =20 contained and you would have to take the prop off to get it of= f and=20 take it apart if one was at least currious what was inside of= =20 it.
 
It's difficult to know if a 4 cyclynder Lycom= ing is=20 as smooth as it can be, because it's not a real smooth engine= under=20 the best of conditions.
 
I inquired to a local=20 experienced prop balance person in Redmond and they concluded= that=20 because of the dynamic balancer on the ring gear, he would not= =20 attempt to balance the engine with his expensive balance work,= as he=20 thought the attached dynamic balancer would change the interna= l=20 weight at will.
 
Does anyone have any experience= with=20 these dynamic balancers attached to the ring=20 gear???
 
Cheers
 
Jack Addison =20 N360JS
near Redmond,=20 OR
=3D
--part1_136f7e.238cb2c5.3a967e66_boundary--