X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from zproxy.gmail.com ([64.233.162.198] verified) by logan.com (CommuniGate Pro SMTP 5.0.8) with ESMTP id 982046 for flyrotary@lancaironline.net; Sun, 12 Feb 2006 17:45:02 -0500 Received-SPF: pass receiver=logan.com; client-ip=64.233.162.198; envelope-from=wdleonard@gmail.com Received: by zproxy.gmail.com with SMTP id m7so1006290nzf for ; Sun, 12 Feb 2006 14:44:17 -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=AK9eMAczPjniCinjLPNL9cF/ffkjMYHjS1us1yXcGgeuTQlwwOBbtRNcoyWv9BH/fCAEcy6/wK+N9YPBqIsz+qPbCsPncoInzbj/XMxQu20zmI6MMknfYJTlYFqER2eapftbg0o1I2DyKw5hAFKWqaleTmmc6snhHYhrEWudUXQ= Received: by 10.65.22.15 with SMTP id z15mr690277qbi; Sun, 12 Feb 2006 14:44:16 -0800 (PST) Received: by 10.65.216.20 with HTTP; Sun, 12 Feb 2006 14:44:16 -0800 (PST) Message-ID: <1c23473f0602121444i4c3fadbfm2acf89fc26b516f5@mail.gmail.com> Date: Sun, 12 Feb 2006 14:44:16 -0800 From: David Leonard To: Rotary motors in aircraft Subject: Re: [FlyRotary] How to attach a muffler In-Reply-To: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_Part_4061_20980173.1139784256560" References: ------=_Part_4061_20980173.1139784256560 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline Monty, that is great info. The turbo - engine is good. I use the stock manifold that is very beefy iron and a very short moment arm. From the turbo outlet I currently have a 16G 321SS down pipe that is about 18" long going right down out of the cowl. Easy enough. I plan to hang the muffler under the cabin, so all I need is one bend going from the current down pipe to the muffler, about 2' away (with another smal= l bend just before the muffler for alignment). I was thinking a slip joint onto the down pipe, then another onto the muffler. Can v-bands be used INSTEAD of slip joints? That would work great and be easy to do. What is a manifold? Can you send me a link to one? Thanks for your help. Dave Leonard On 2/12/06, M Roberts wrote: > > 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 > -- 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_4061_20980173.1139784256560 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline
Monty, that is great info. 
 
The turbo - engine is good.  I use the stock manifold that is ver= y beefy iron and a very short moment arm. 
 
From the turbo outlet I currently have a 16G 321SS down pipe = ;that is about 18" long going right down out of the cowl.  Easy e= nough.
 
I plan to hang the muffler under the cabin, so all I need is one bend = going from the current down pipe to the muffler, about 2' away (with anothe= r small bend just before the muffler for alignment).  I was thinking a= slip joint onto the down pipe, then another onto the muffler. =20
 
Can v-bands be used INSTEAD of slip joints?  That would work grea= t and be easy to do.
What is a manifold?  Can you send me a link to one?
 
Thanks for your help.
 
Dave Leonard

 
On 2/12/06, = M Roberts <montyr2157@allte= l.net> wrote:
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
<= br>

--
Dave Leonard
Turbo Rotary RV-6 N4VY
<= a href=3D"http://members.aol.com/_ht_a/rotaryroster/index.html">http://memb= ers.aol.com/_ht_a/rotaryroster/index.html
http:= //members.aol.com/_ht_a/vp4skydoc/index.html=20 ------=_Part_4061_20980173.1139784256560--