X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Fri, 13 Aug 2010 14:43:29 -0400 Message-ID: X-Original-Return-Path: Received: from hrndva-omtalb.mail.rr.com ([71.74.56.122] verified) by logan.com (CommuniGate Pro SMTP 5.3.8) with ESMTP id 4429732 for lml@lancaironline.net; Fri, 13 Aug 2010 11:49:40 -0400 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=mWMe3HXt1P3ELXxrmMgI9QKdSRnwjSxQbBh3ay0KAh4= c=1 sm=0 a=MHZY6FYWMEQOp7S43i2QIw==:17 a=3oc9M9_CAAAA:8 a=Ia-xEzejAAAA:8 a=x2ruqFfzAAAA:8 a=rTjvlri0AAAA:8 a=84aR13__AAAA:8 a=C_IRinGWAAAA:8 a=VMcUJ-LzJfY1jZ_diNwA:9 a=12haekCWAO18snT-X-cbknXTdcoA:4 a=wPNLvfGTeEIA:10 a=vNaDsT68qR4A:10 a=U8Ie8EnqySEA:10 a=EzXvWhQp4_cA:10 a=Dr9Wx-Q63l4A:10 a=Pn-vBCPl5NIA:10 a=si9q_4b84H0A:10 a=jdkGA4AoyLNi4FUM:21 a=UxJKMr-aGZBPcEF1:21 a=oMrcAJYzeZRdSgykT8IA:9 a=53ywkBWgpzo4mZxMjwQA:7 a=139Y_rn61joSEXZePGbyEZSBjW4A:4 a=MHZY6FYWMEQOp7S43i2QIw==:117 X-Cloudmark-Score: 0 X-Originating-IP: 74.218.201.50 Received: from [74.218.201.50] ([74.218.201.50:2163] helo=Lobo) by hrndva-oedge03.mail.rr.com (envelope-from ) (ecelerity 2.2.2.39 r()) with ESMTP id CC/DF-21482-079656C4; Fri, 13 Aug 2010 15:49:04 +0000 X-Original-Message-ID: <001001cb3aff$0c1fe740$6401a8c0@Lobo> From: "Wolfgang" X-Original-To: Subject: Re: [LML] Re: Prop Balance X-Original-Date: Fri, 13 Aug 2010 11:49:00 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_000D_01CB3ADD.84CDE2E0" 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_000D_01CB3ADD.84CDE2E0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable There are two types of vibration in piston engines, torsional and = lateral. Torsional vibration is from the power stroke of the pistons as = the combustion gasses burn and lateral vibration is from a net imbalance = in the rotating masses. The balance checking equipment described so far = is only checking the lateral vibration . . . and then only in one plane, = at the front of the engine. To check dynamic balance, the rotating mass = needs to be checked in two parallel planes, one at the front of the = crank shaft and the other at the rear of the crank shaft. This allows = for checking "wobble" of the engine. The front could be out of balance = at one angle and the rear could be out of balance at another angle. This = is checked on car wheels by automatic machines that determine weights to = be applied both inside and outside of the rims. The silicon filled harmonic balancer does help with engine vibration but = only the torsional vibration. If the silicon suspended weight is allowed = to move laterally then some lateral vibration can be compensated = automatically. Wolfgang -------------------------------------------------------------------------= ------- From: Sky2high@aol.com=20 Sender: =20 Subject: Re: [LML] Re: Prop Balance=20 Date: Thu, 12 Aug 2010 22:54:41 -0400=20 To: lml@lancaironline.net=20 =20 =20 Wolfgang, The harmonic damper you refer to (12 pounds, bolts to Lyc = flywheel) contains a steel ring in viscous silicone. Its purpose is to = dampen negative torque pulses and to provide for more flywheel momentum. = It is especially effective for light wooden props (rpm increase of = approximately 100) but also serves it purpose with CS props even though = the result appears to be un-measurable. Review the torsional effects = of a 4 cylinder engine here: =20 = http://www.epi-eng.com/piston_engine_technology/torsional_excitation_from= _piston_engines.htm It contributes nothing to dynamic prop balance :-(=20 Grayhawk In a message dated 8/12/2010 3:45:09 P.M. Central Daylight Time, = Wolfgang@MiCom.net writes: Or put a silicon filled balance ring at the prop hub :-) Wolfgang ------------------------------------------------------------------------ From: "Kent" =20 Sender: =20 Subject: Re: [LML] Re: Prop Balance=20 Date: Thu, 12 Aug 2010 14:28:09 -0400=20 To: lml@lancaironline.net=20 =20 =20 Vibration sensor is placed on engine to measure how engine = is moving in space. Prop imbalance will make engine move in bigger circle. So mayny Millivolts are genrated per vibration severity. Relative location of heavy spot is signaled by photo = cell, or strobe light flash as heavy spot passes and polarity changes. = Up-down =3D plus-minus. The prop's static weigh slugs can be adjusted or large = area washers can be bolted to spinner bulkhead to counterbalance the = heavy spot. How much depends weigh depends on how much imbalance there = was to begin with. Common to have 10-30 grams of weight for a momento of = 100-200 inch pounds. Kent Felkins Tulsa Oklahoma ----- Original Message ----- From: "Greenbacks, UnLtd." = To: Sent: Thursday, August 12, 2010 7:20 AM Subject: [LML] Re: Prop Balance Could one of you describe the process of dynamically = balancing a typical prop? My old brain cannot visualize how weights are attached. Angier Ames N4ZQ --=20 =20 ------=_NextPart_000_000D_01CB3ADD.84CDE2E0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
There are two types of vibration in = piston engines,=20 torsional and lateral. Torsional vibration is from the power stroke of = the=20 pistons as the combustion gasses burn and lateral vibration is from a = net=20 imbalance in the rotating masses. The balance checking equipment = described so=20 far is only checking the lateral vibration . . . and then only in one = plane, at=20 the front of the engine. To check dynamic balance, the rotating mass = needs to be=20 checked in two parallel planes, one at the front of the crank shaft and = the=20 other at the rear of the crank shaft. This allows for checking "wobble" = of the=20 engine. The front could be out of balance at one angle and the rear = could be out=20 of balance at another angle. This is checked on car wheels by automatic = machines=20 that determine weights to be applied both inside and outside of the=20 rims.
 
The silicon filled harmonic = balancer does help=20 with engine vibration but only the torsional vibration. If the silicon = suspended=20 weight is allowed to move laterally then some lateral vibration can be=20 compensated automatically.
 
Wolfgang
lml@lancaironline.net
From: Sky2high@aol.com
Sender: <marv@lancaironline.net>
Subject: Re: [LML] Re: Prop = Balance
Date: Thu, 12 Aug 2010 22:54:41 = -0400
To:
Wolfgang,
 
The harmonic damper you refer to (12 pounds, bolts to Lyc = flywheel)=20 contains a steel ring in viscous silicone.  Its purpose is to = dampen=20 negative torque pulses and to provide for more flywheel = momentum.  It=20 is especially effective for light wooden props (rpm increase of=20 approximately 100) but also serves it purpose with CS = props even=20 though the result appears to be = un-measurable.  =20 Review the torsional effects of a 4 cylinder engine=20 here:  
 
http://www.epi-eng.com/piston_engine_technology/torsional_= excitation_from_piston_engines.htm
 
It contributes nothing to dynamic prop balance = :-( 
 
Grayhawk
 
In a message dated 8/12/2010 3:45:09 P.M. Central Daylight = Time,=20 Wolfgang@MiCom.net writes:
Or put a silicon filled balance = ring at the=20 prop hub :-)
 
Wolfgang
<marv@lancaironline.net>lml@lancaironline.net
From: "Kent"=20 <kent@tulsaconnect.com>
Sender:
Subject: Re: [LML] Re: Prop=20 Balance
Date: Thu, 12 Aug 2010 = 14:28:09=20 -0400
To:
Vibration sensor is placed on = engine to=20 measure how engine is moving in space.
Prop imbalance = will make=20 engine move in bigger circle.
So mayny Millivolts are = genrated=20 per vibration severity.

Relative location of heavy = spot is=20  signaled by photo cell, or strobe light flash as = heavy spot=20 passes and polarity changes.  Up-down =3D=20 plus-minus.

The prop's static weigh slugs can be = adjusted=20 or large area washers can be bolted to spinner bulkhead to = counterbalance the heavy spot.

How much depends = weigh=20 depends on how much imbalance there was to begin=20 with.

Common to have 10-30 grams of weight for a = momento of=20 100-200 inch pounds.


Kent Felkins
Tulsa=20 Oklahoma

----- Original Message ----- From: = "Greenbacks,=20 UnLtd." <N4ZQ@comcast.net>
To:=20 <lml@lancaironline.net>
Sent: Thursday, August = 12, 2010=20 7:20 AM
Subject: [LML] Re: Prop Balance


Could one of you describe the process of=20 dynamically balancing a
typical prop?
My old brain = cannot=20 visualize how weights are attached.

Angier=20 = Ames
N4ZQ

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