X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from zproxy.gmail.com ([64.233.162.207] verified) by logan.com (CommuniGate Pro SMTP 5.0.8) with ESMTP id 982126 for flyrotary@lancaironline.net; Sun, 12 Feb 2006 17:52:13 -0500 Received-SPF: pass receiver=logan.com; client-ip=64.233.162.207; envelope-from=wdleonard@gmail.com Received: by zproxy.gmail.com with SMTP id 16so848404nzp for ; Sun, 12 Feb 2006 14:51:28 -0800 (PST) DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:message-id:date:from:to:subject:in-reply-to:mime-version:content-type:references; b=puodqQY2YJxmhNC2x0RURycSnxII+dTCD7Pe7+G7MjReVIGUC+SHjwji3503z7qYSEbnDPhzrqm2fiekhIIroBmPnL4tnBgxaYpuq8GrTjj0XNzLEUc+1th0C5n2l3nmM3uYu9Rhqbvr4z/ACwlgHe7DcDPa1yI4jldId1jSk/w= Received: by 10.65.180.18 with SMTP id h18mr692724qbp; Sun, 12 Feb 2006 14:51:27 -0800 (PST) Received: by 10.65.216.20 with HTTP; Sun, 12 Feb 2006 14:51:27 -0800 (PST) Message-ID: <1c23473f0602121451p4ddea734q1dcae05bbea61f79@mail.gmail.com> Date: Sun, 12 Feb 2006 14:51:27 -0800 From: David Leonard To: Rotary motors in aircraft Subject: Re: [FlyRotary] Re: How to attach a muffler In-Reply-To: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_Part_4145_16992345.1139784687853" References: ------=_Part_4145_16992345.1139784687853 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline Thanks Bernie. Flexible SS would work great. Would you happen to have a link to a good source? Does it seem to hold up OK? Did you put a heat shield above the muffler to protect the paint? Dave Leonard On 2/12/06, WALTER B KERR wrote: > > > > On Sun, 12 Feb 2006 12:20:29 -0600 "M Roberts" > writes: > > So I am trying to plan my muffler installation. I just bought a > hushmaster II to hang under the cabin. I want the exhaust the exit where= it > currently does mid cowl. > > The question is how to make the connection. It seems that if I make rigi= d > connections then I will get fatigue cracks in the exhaust, even if I supp= ort > the weight of the muffler. Do the pipes themselves just absorb the > vibration of the engine? > > I need to use either a slip fit or a v-band clamp to remove the pipe to > get the cowl off. Will either of these provide enough play in the system= . > > Flowmaster also sells a ball-and-socket type of joint. http://www.flowmas= termufflers.com/products/index.phpmain_page=3Dproduct_info&products_id=3D23= 17 > > That seems better in terms of flexibility, but is more costly and will > probably let more heat into the cowl, and will need a larger cowl opening > (would prefer the slip or v-band joint). > > Am I worried about nothing? > -- > Dave Leonard > Turbo Rotary RV-6 N4VY > > > > > > David, > > You are most definitely not "worried about nothing". When I worked with > rocket engines, there was a tremendous amount of effort placed in making > sure that there was no stress imposed on the piping due to temperature > changes and vibration. Granted rockets see much larger extremes in temp d= ue > to cryogenic temps and very high stoiciometric combustion right next to = it. > But the principles are the same. > > In the ideal world you would use very thin inconel and place a slip joint > at each length between any fixed object (turbo, engine block, muffler). A= ny > bend would also have a slip joint before and after it so that both torsio= n > and expansion is eliminated. Each slip joint gets a metal bellows to seal= it > and allow relative motion. Then you have to look very closely at how you > mount and constrain each piece of plumbing. Your exhaust would cost $5K > > In the real world, most of what we use is heavy enough that you don't hav= e > to go to such lengths. In auto use the pipe is so heavy and the stresses = low > enough that these are usually not a concern. We are closer to the Auto t= han > the rocket. > > I would mount the muffler so that it can move a bit using silicone or wir= e > rope isolators. Then I would use a stainless or inconel metal bellows wit= h > the wire mesh constraint (front wheel drive auto) to let the engine move > around also. I really like V-band clamps for joints. How the mounts are > placed and muffler oriented really determines the detail design here. > > Post some pics and drawings. > > Sorry about your engine woes. > > Monty > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D > > Hi David, > > I kinda copied Tracy Hush II installation. Come off the exhaust stack wit= h > a peice of SS flex tube about 12 inches long into the muffler. Hang the I > hung the muffler from two places with battery/ ground strapping material = and > then attempted to isolate it when I fastened it at the beefed up floor. > > Can send some pictures if you are interested. > > Bernie > > > -- Dave Leonard Turbo Rotary RV-6 N4VY http://members.aol.com/_ht_a/rotaryroster/index.html http://members.aol.com/_ht_a/vp4skydoc/index.html ------=_Part_4145_16992345.1139784687853 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline
Thanks Bernie.  Flexible SS would work great.  Would you hap= pen to have a link to a good source?   Does it seem to hold up OK= ?
 
Did you put a heat shield above the muffler to protect the paint?
 
Dave Leonard

 
On 2/12/06, = WALTER B KERR <jbker@juno.com&= gt; wrote:
 
 
On Sun, 12 Feb 2006 12:20:29 -0600 "M Roberts" <montyr2157@alltel.net> writes:
=
So I am trying to pl= an my muffler installation.  I just bought a hushmaster II to hang und= er the cabin.  I want the exhaust the exit where it currently does mid= cowl.
 
The question is how = to make the connection.  It seems that if I make rigid connections the= n I will get fatigue cracks in the exhaust, even if I support the weight of= the muffler.  Do the pipes themselves just absorb the vibration of th= e engine? =20
 
I need to use either= a slip fit or a v-band clamp to remove the pipe to get the cowl off. = Will either of these provide enough play in the system.
 
That seems better in= terms of flexibility, but is more costly and will probably let more heat i= nto the cowl, and will need a larger cowl opening (would prefer the slip or= v-band joint).
 
Am I worried about n= othing?
--
Dave Leonard<= br>Turbo Rotary RV-6 N4VY
 
 
 
 
 
David,
 
You are most definitely not "worr= ied about nothing". When I worked with rocket engines, there was a tre= mendous amount of effort placed in making sure that there was no stress imp= osed on the piping due to temperature changes and vibration. Granted rocket= s see much larger extremes in temp due to  cryogenic temps and very hi= gh stoiciometric combustion right next to it. But the principles are the sa= me.=20
 
In the ideal world you would use very = thin inconel and place a slip joint at each length between any fi= xed object (turbo, engine block, muffler). Any bend would also have a slip = joint before and after it so that both torsion and expansion is eliminated.= Each slip joint gets a metal bellows to seal it and allow relative motion.= Then you have to look very closely at how you mount and constrain each pie= ce of plumbing. Your exhaust would cost $5K
 
In the real world, most of what we use= is heavy enough that you don't have to go to such lengths. In auto use the= pipe is so heavy and the stresses low enough that these are usually&n= bsp; not a concern. We are closer to the Auto than the rocket.=20
 
I would mount the muffler so that it c= an move a bit using silicone or wire rope isolators. Then I would use a sta= inless or inconel metal bellows with the wire mesh constraint (front w= heel drive auto) to let the engine move around also. I really like V-band c= lamps for joints. How the mounts are placed and muffler oriented really det= ermines the detail design here.
 
Post some pics and drawings.
 
Sorry about your engine woes.
 
Monty
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
 
Hi David,
 
I kinda copied Tracy Hush II installat= ion. Come off the exhaust stack with a peice of SS flex tube about 12 inche= s long into the muffler. Hang the I hung the muffler from two places with b= attery/ ground strapping material and then attempted to isolate it when I f= astened it at the beefed up floor.
 
Can send some pictures if you are inte= rested.
 
Bernie
 



= --
Dave Leonard
Turbo Rotary RV-6 N4VY
http://members.aol.com/_ht_a/rotaryr= oster/index.html
http:= //members.aol.com/_ht_a/vp4skydoc/index.html=20 ------=_Part_4145_16992345.1139784687853--