X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from ms-smtp-03.southeast.rr.com ([24.25.9.102] verified) by logan.com (CommuniGate Pro SMTP 5.1c.3) with ESMTP id 1348802 for flyrotary@lancaironline.net; Fri, 25 Aug 2006 16:58:31 -0400 Received-SPF: pass receiver=logan.com; client-ip=24.25.9.102; envelope-from=eanderson@carolina.rr.com Received: from edward2 (cpe-024-074-111-186.carolina.res.rr.com [24.74.111.186]) by ms-smtp-03.southeast.rr.com (8.13.6/8.13.6) with SMTP id k7PKvnlJ004443 for ; Fri, 25 Aug 2006 16:57:50 -0400 (EDT) Message-ID: <005601c6c889$25f29f10$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Exhaust system Date: Fri, 25 Aug 2006 16:57:59 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0053_01C6C867.9E996EC0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.2869 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2900.2962 X-Virus-Scanned: Symantec AntiVirus Scan Engine This is a multi-part message in MIME format. ------=_NextPart_000_0053_01C6C867.9E996EC0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Chris, I don't think we have a cut and dried answer.=20 Certainly different airframes (pusher vs puller) certainly present = different factors for consideration - I for one don't have to worry = about any part of my exhaust going through my prop. Second is the = heat factor, there is no question a muffler tucked up inside the cowl = presents a more aesthetic (and less drag) solution - however, it also = provides a high BTU oven under the cowl with attendant heat problems. I = have two straight tubes 2" dia with two 3 1/2" dia shells as mufflers. = I say shells because I have not been able to find any arrangement of = internal baffles that survive the pounding of the exhaust pulse. The Hush Master probably presents the best current solution if hanging = it under the airframe as its fairly streamlined, can take the punishment = and fairly effective in reducing the noise. The spin tech worked well, = but was not streamlined and was fairly heavy. Biggest draw back was the = flat surface to the airstream. I have not heard any results of the = spiral type - I'm interested because I could possible stuff some in my = shells. That's my 0.02 worth Ed Ed Anderson Rv-6A N494BW Rotary Powered Matthews, NC eanderson@carolina.rr.com http://members.cox.net/rogersda/rotary/configs.htm#N494BW ----- Original Message -----=20 From: the mallorys=20 To: Rotary motors in aircraft=20 Sent: Friday, August 25, 2006 4:41 PM Subject: [FlyRotary] Exhaust system I've looked back through the archives, and seen lots of different = ideas for exhaust systems. But no real definitive answers. There is the Cool tube exhaust that has very short pipes,like Bob = White posted. There is the medium length, no muffler system like Buly has or like = Joe Hull has mocked up. There is the really long tubes with muffler hanging under belly like = Tracy has. Do we know what the correct length tube is to tune the exhaust for our = RPMs? Does this length include the muffler? It appears the diameter most used is from 1.5 to 2". What about the different mufflers? I only found two mufflers named in = the archive that guys are happy with, the Flowmaster Hushpower II, and = the Moroso Spiral Flow Racing Mufflers. Last year at Shady Bend, Monti = talked about noise levels and testing different mufflers and pipes. Are = there ant results from that? I'm ready to start mocking up my exhaust, so am seeking the collective = wisdom of the group. Chris ------=_NextPart_000_0053_01C6C867.9E996EC0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Chris, I don't think we have a cut and dried=20 answer. 
 
 Certainly different airframes (pusher vs = puller)=20 certainly present different factors for consideration - I for one = don't=20 have to worry about any part of my exhaust  going through my=20 prop.   Second is the heat factor, there is no question a = muffler=20 tucked up inside the cowl presents a more aesthetic (and less drag) = solution -=20 however, it also provides a high BTU oven under the cowl with attendant = heat=20 problems.  I have two straight tubes 2" dia with two 3 1/2" dia = shells as=20 mufflers.  I say shells because I have not been able to find any=20 arrangement of internal baffles that survive the pounding of the = exhaust=20 pulse.
 
The Hush Master probably presents the best = current=20 solution if hanging it under the airframe as its fairly streamlined, can = take=20 the punishment and fairly effective in reducing the noise.  The = spin tech=20 worked well, but was not streamlined and was fairly heavy.  Biggest = draw=20 back was the flat surface to the airstream.    I have not = heard=20 any results of the spiral type - I'm interested because I could possible = stuff=20 some in my shells.
 
That's my 0.02 worth
 
Ed
 
Ed Anderson
Rv-6A N494BW Rotary = Powered
Matthews,=20 NC
eanderson@carolina.rr.comhttp:/= /members.cox.net/rogersda/rotary/configs.htm#N494BW
----- Original Message -----
From:=20 the=20 mallorys
Sent: Friday, August 25, 2006 = 4:41=20 PM
Subject: [FlyRotary] Exhaust = system

I've looked back through the = archives, and seen=20 lots of different ideas for exhaust systems.  But no real = definitive=20 answers.
 
There is the Cool tube exhaust that = has very=20 short pipes,like Bob White posted.
There is the medium length, no = muffler system=20 like Buly has or like Joe Hull has mocked up.
There is the really long tubes with = muffler=20 hanging under belly like Tracy has.
 
Do we know what the correct length = tube is to=20 tune the exhaust for our RPMs?  Does this length include the=20 muffler?
 
It appears the diameter most used is = from 1.5 to=20 2".
 
What about the different = mufflers?  I=20 only found two mufflers named in the archive that guys are happy=20 with, the Flowmaster Hushpower II, and=20 the Moroso Spiral Flow = Racing=20 Mufflers.  Last year at Shady Bend, = Monti talked=20 about noise levels and testing different mufflers and pipes.  Are = there=20 ant results from that?
 
I'm ready to start mocking up my = exhaust, so am=20 seeking the collective wisdom of the group.
 
Chris
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