X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from fed1rmmtao104.cox.net ([68.230.241.42] verified) by logan.com (CommuniGate Pro SMTP 5.3c3) with ESMTP id 4004852 for flyrotary@lancaironline.net; Sun, 06 Dec 2009 10:59:00 -0500 Received-SPF: none receiver=logan.com; client-ip=68.230.241.42; envelope-from=alventures@cox.net Received: from fed1rmimpo03.cox.net ([70.169.32.75]) by fed1rmmtao104.cox.net (InterMail vM.8.00.01.00 201-2244-105-20090324) with ESMTP id <20091206155823.QCDS15311.fed1rmmtao104.cox.net@fed1rmimpo03.cox.net> for ; Sun, 6 Dec 2009 10:58:23 -0500 Received: from BigAl ([72.192.141.69]) by fed1rmimpo03.cox.net with bizsmtp id DryP1d0031W2PoQ04ryP2N; Sun, 06 Dec 2009 10:58:23 -0500 X-VR-Score: 0.00 X-Authority-Analysis: v=1.1 cv=+jAW79NKwrNAYaynTXPjtTngPQL9M8sBtdBfwSVg0dQ= c=1 sm=1 a=uRdPTVUZDD8A:10 a=X4y9SBka+FAc+vv68blzUg==:17 a=Ia-xEzejAAAA:8 a=7g1VtSJxAAAA:8 a=XzKJJHbjzPN2neLMgKwA:9 a=fNhfN0pa67KeiTZUUL4A:7 a=temxea84P4kfn6uQU-62dx75KrYA:4 a=EzXvWhQp4_cA:10 a=Cj-tnKRuS1HfuedL:21 a=GrsHUC80604SF3JF:21 a=EnHNNCmBakkZ3LEuqWoA:9 a=DjwoAKHmh_tDeNLz0r4A:7 a=F3IK9YXnz6cO1jF1c1MmFkrI-u4A:4 a=X4y9SBka+FAc+vv68blzUg==:117 X-CM-Score: 0.00 From: "Al Gietzen" To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] Exhaust Manifold material Date: Sun, 6 Dec 2009 07:58:28 -0800 Message-ID: <571510BF43C5428D99D2F4F78C49C4AA@BigAl> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_000B_01CA7649.E536E270" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.6856 Thread-Index: Acp2arR6/GP3czDsTQedHvuh3Ubl6AAHE2wg Importance: Normal In-Reply-To: X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.5579 This is a multi-part message in MIME format. ------=_NextPart_000_000B_01CA7649.E536E270 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Phil; =20 I know you=92re asking Ed, but hope you don=92t mind another opinion. Both 304 and 321 SS are subject to inter-granular stress corrosion at = the temps we=92re talking about. 321 is a better choice and will last = longer, and could be lighter by some reduction of thicknesses. =20 Yes, making it thicker will make the 304 last longer by lowering stress, = but it is still subject to limited life, and at the thicknesses you suggest, = my estimate is your system will be rather massive at close to 30 lbs. =20 I don=92t know the details of his design, But Dave Atkins had a SS = tangential man/muff that basically crumbled to pieces within a couple hundred = hours. =20 I=92d also suggest a larger diameter for the tangential muffler; like = 5+=94. This allows for more expansion which lowers both temp and pulse = strengths. Flat ends would definitely be a failure point. Reinforcing with a = central tube would be a big help, but I would still make them conical, or = concave inward. =20 I know that inconel kicks up the cost a fair amount, but it gets you = away from the stress corrosion issue and allows a system of about 1/3 the = weight of what your considering. When you consider the overall time, effort, = cost, risk, and weight, I still think inconel comes out on top. My inconel tangential muffler weighs in at about 12#; including the rather massive = RB exhaust flange. The 321 secondary muffler and exit pipe add another 3 = =BD#. It has now been running for 170 hours; and as far as I can tell, is = about as sound as when it started. =20 Al =20 From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Phil White Sent: Sunday, December 06, 2009 3:53 AM To: Rotary motors in aircraft Subject: [FlyRotary] Exhaust Manifold material =20 Ed Anderson: I recall (if memory can be trusted?) that you are using=20 304 stainless for your exhaust manifold. I am wanting to make a=20 tangential muffler for my 20B, and wonder if the following might last a=20 reasonable time: =20 1. From the ports; 2" x .150 wall 2. Tangential tube; 4" x .120 wall 3. Exhaust pipe; 2.5" x .120 wall 4. End caps on tangential pipe; .125 plate 5. Center tube (to help swirl, and to reinforce end caps); 3/4" x=20 .080 wall (wondered if it would be a good or bad idea to run cool air=20 through this to cool it and the exhaust a bit, or better to leave the=20 ends closed??) =20 Are these walls heavy enough to last? Or is using $175 worth of 304 = a waste of time and money compared to getting the more expensive 321=20 stainless? Your opinion is most welcome. =20 Phil in IL =20 -- Homepage: http://www.flyrotary.com/ Archive and UnSub: http://mail.lancaironline.net:81/lists/flyrotary/List.html ------=_NextPart_000_000B_01CA7649.E536E270 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

Phil;

 

I know you’re asking Ed, but hope you = don’t mind another opinion.

Both 304 and 321 SS are subject to inter-granular = stress corrosion at the temps we’re talking about.=A0 321 is a better choice and = will last longer, and could be lighter by some reduction of thicknesses.

=A0

Yes, making it thicker will make the 304 last = longer by lowering stress, but it is still subject to limited life, and at the thicknesses you suggest, my estimate is your system will be rather = massive at close to 30 lbs.

 

I don’t know the details of his design, But = Dave Atkins had a SS = tangential man/muff that basically crumbled to pieces within a couple hundred = hours.

 

I’d also suggest a larger diameter for the tangential muffler; like 5+”.=A0 This allows for more expansion = which lowers both temp and pulse strengths. Flat ends would definitely be a = failure point.=A0 Reinforcing with a central = tube would be a big help, but I would still make them conical, or concave = inward.

 

I know that inconel kicks up the cost a fair = amount, but it gets you away from the stress corrosion issue and allows a system of = about 1/3 the weight of what your considering. =A0When you consider the = overall time, effort, cost, risk, and weight, I still think inconel comes out on top.=A0 My = inconel tangential muffler weighs in at about 12#; including the rather massive = RB exhaust flange.=A0 The 321 secondary muffler and exit pipe add another 3 = =BD#.=A0 It has now been running for 170 hours; and as far as I can tell, is about = as sound as when it started.

 

Al

 

From: Rotary motors in aircraft = [mailto:flyrotary@lancaironline.net] On Behalf Of Phil White
Sent: Sunday, December 06, 2009 3:53 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Exhaust Manifold material

 

Ed Anderson:=A0=A0=A0 I recall (if memory can be trusted?) that you are = using

304 stainless for your exhaust manifold.=A0 I am wanting to make a =

tangential muffler for my 20B, and wonder if the following might last a =

reasonable time:=A0

1.=A0=A0 From the ports;=A0 2" x .150 wall

2.=A0=A0 Tangential tube;=A0 4" x .120 wall

3.=A0=A0 Exhaust pipe;=A0 2.5" x .120 wall

4.=A0=A0 End caps on tangential pipe;=A0 .125 plate

5.=A0=A0 Center tube (to help swirl, and to reinforce end caps);=A0 3/4" x =

.080 wall=A0 (wondered if it would be a good or bad idea to run cool air =

through this to cool it and the exhaust a bit, or better to leave the =

ends closed??)

 

=A0=A0=A0 Are these walls heavy enough to last?=A0 Or is using $175 worth of 304 =

a waste of time and money compared to getting the more expensive 321 =

stainless?=A0 Your opinion is most welcome.

 

Phil in IL

 

--

Homepage:=A0 http://www.flyrotary.com/

Archive and UnSub:=A0=A0 = http://mail.lancaironline.net:81/lists/flyrotary/List.html<= /p>

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