X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from imr-da06.mx.aol.com ([205.188.169.203] verified) by logan.com (CommuniGate Pro SMTP 6.0.4) with ESMTP id 6197975 for flyrotary@lancaironline.net; Fri, 12 Apr 2013 16:10:38 -0400 Received-SPF: pass receiver=logan.com; client-ip=205.188.169.203; envelope-from=Lehanover@aol.com Received: from mtaomg-mb02.r1000.mx.aol.com (mtaomg-mb02.r1000.mx.aol.com [172.29.41.73]) by imr-da06.mx.aol.com (Outbound Mail Relay) with ESMTP id 4B6621C0000BA for ; Fri, 12 Apr 2013 16:10:02 -0400 (EDT) Received: from core-moe002c.r1000.mail.aol.com (core-moe002.r1000.mail.aol.com [172.29.188.69]) by mtaomg-mb02.r1000.mx.aol.com (OMAG/Core Interface) with ESMTP id EC52BE000086 for ; Fri, 12 Apr 2013 16:10:01 -0400 (EDT) From: Lehanover@aol.com Full-name: Lehanover Message-ID: <75c1.6e823e2e.3e99c419@aol.com> Date: Fri, 12 Apr 2013 16:10:01 -0400 (EDT) Subject: Re: [FlyRotary] Re: Muffler designs To: flyrotary@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="part1_75c1.6e823e2e.3e99c419_boundary" X-Mailer: AOL 9.7 sub 55 X-Originating-IP: [173.88.28.139] x-aol-global-disposition: G DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mx.aol.com; s=20121107; t=1365797402; bh=3vvz5piPiPepwK7n9/6Erx4SL9SqaEO4wqMNTsApoOY=; h=From:To:Subject:Message-ID:Date:MIME-Version:Content-Type; b=cu7iEAwiqkYsyOVe0TYL/bqfIws2Ctzx44YqWRvhxf0YkpwrW4gWxhfILpqiEny/v iQS1Svs9aKigmdmbhQtpwbUQ0/o8P3+boholZDtyNZf+b8HUw1p0wQfKq3k3ACntyY 96I2mFY2KaJqVVXdpqa1sKseY4Bzx7A9t9u8vSl0= X-AOL-SCOLL-SCORE: 0:2:405656320:93952408 X-AOL-SCOLL-URL_COUNT: 0 x-aol-sid: 3039ac1d294951686a192774 --part1_75c1.6e823e2e.3e99c419_boundary Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit As in electronics, the fourth harmonic of a frequency is the strongest. So damping that harmonic reduces the effect of the primary frequency. You can see in this picture how the smaller chambers are closer to the end of the pipe and the larger chamber closer to the opposite end. The intake noise is a very large part of the engines total noise profile. Intake valves shutting off a fast moving air column at various RPM is the problem. Similar chamber sizes appear inside complex exhaust mufflers in automobiles. Absorbing the peak pressure waves from the Mazda and letting them back into the stream during low pressure troughs is what seems the lightest and least complex mufflers being tried. Since aircraft engines operate at just a few RPM, it seams that various lengths of muffler, mounted at various distances from the engine should be investigated. Or, I could be completely wrong. Lynn E. Hanover In a message dated 4/11/2013 11:46:50 P.M. Eastern Daylight Time, hoursaway1@comcast.net writes: Marty, Lynn and others Attached is a picture of an intake tube for a Ford pickup truck. It got me thinking about what was Ford thinking?!?!! And from there, how could we use this. The intake air comes in from the left. It travels past a series of deadend offshoots, of different sizes. Then enters the throttle body after the turn at the bottom. In designing the mufflers for our rotaries, there are different pitches that are troublesome. Would a design similar to this work for our ear shattering vibs, and let the throaty V-8 sound thru? Just wondering Bob Tilley --part1_75c1.6e823e2e.3e99c419_boundary Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable
As in electronics, the fourth harmonic of a frequency is the= =20 strongest. So damping that harmonic reduces the effect of the primary= =20 frequency. You can see in this picture how the smaller chambers are closer = to=20 the end of the pipe and the larger chamber closer to the opposite end. The= =20 intake noise is a very large part of the engines total noise profile. Intak= e=20 valves shutting off a fast moving air column at various RPM is the=20 problem.
 
Similar chamber sizes appear inside complex exhaust mufflers i= n=20 automobiles.
Absorbing the peak pressure waves from the Mazda and letting t= hem=20 back into the stream during low pressure troughs is what
seems the lightest and least complex mufflers being tried.=20 Since
aircraft engines operate at just a few RPM, it seams that vari= ous=20 lengths of muffler, mounted at various distances from the engine should be= =20 investigated. Or, I could be completely wrong.
Lynn E. Hanover 
 
In a message dated 4/11/2013 11:46:50 P.M. Eastern Daylight Time,=20 hoursaway1@comcast.net writes:
= Marty, Lynn and others

Attached is a picture of= an=20 intake tube for a Ford pickup truck. It got me thinking about what was Fo= rd=20 thinking?!?!!  And from there, how could we use this. The intake air= =20 comes in from the left. It travels past a series of deadend offshoots, of= =20 different sizes. Then enters the throttle body after the turn at the=20 bottom. 

In designing the mufflers for our rotaries, there ar= e=20 different pitches that are troublesome. Would a design similar to this wo= rk=20 for our ear shattering vibs, and let the throaty V-8 sound thru?

J= ust=20 wondering
Bob=20 Tilley
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