X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from wa-out-1112.google.com ([209.85.146.180] verified) by logan.com (CommuniGate Pro SMTP 5.2.11) with ESMTP id 3414974 for flyrotary@lancaironline.net; Wed, 07 Jan 2009 12:51:14 -0500 Received-SPF: pass receiver=logan.com; client-ip=209.85.146.180; envelope-from=rwstracy@gmail.com Received: by wa-out-1112.google.com with SMTP id j4so4521108wah.3 for ; Wed, 07 Jan 2009 09:50:37 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:message-id:date:from:sender :to:subject:in-reply-to:mime-version:content-type:references :x-google-sender-auth; bh=bzradVHlBtWQj6/eQgdv9oswEuJpyxztkekg767kQzY=; b=nS37ekhaJoBXu5pLoIo53RAcMNNDcnIZ/i5o7DKmqYJPwE+6pySTmK4+SPfkS5MaZB XUHIsQCkfEWSiMwEFdO4dBZDBOu5rvmC1d122+G2DYrEdV0UluSo0se872fZBplKws4w hc68nT/DTogVQfSFx5zLuwzpvHznDs9OYhVpo= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:sender:to:subject:in-reply-to:mime-version :content-type:references:x-google-sender-auth; b=kKHUyoe+GpWypIYzMZ0CGyEf7djNCZdWjPAboCYqMq6duompeux9encTlbQnvO9QT7 GAa7gUMfm11llfn0UDaHacgzbdERA2i5zkAL81K9mELZniOXKyMrkClyADfDkq2ub3FT g+jOio3T+r3aw0CT8JuYdgmwRFPZiA6tFwHus= Received: by 10.114.181.6 with SMTP id d6mr15434563waf.8.1231350637337; Wed, 07 Jan 2009 09:50:37 -0800 (PST) Received: by 10.114.61.10 with HTTP; Wed, 7 Jan 2009 09:50:37 -0800 (PST) Message-ID: <1b4b137c0901070950o6654a0a2s3805812eca833f8f@mail.gmail.com> Date: Wed, 7 Jan 2009 12:50:37 -0500 From: "Tracy Crook" Sender: rwstracy@gmail.com To: "Rotary motors in aircraft" Subject: Re: [FlyRotary] Re: Muffler design (was 20B isssues . . ) In-Reply-To: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_Part_207957_30902834.1231350637332" References: X-Google-Sender-Auth: 48f531be67d34344 ------=_Part_207957_30902834.1231350637332 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline Agreed, this is definitely a new concept and I hope it works. The only thing that bothers me is that, as you pointed out, the bandwidth needed for attenuation is about 0 to 12 Khz. That represents MANY octaves even if we bump the lower limit to a realistic number ( only a closed pipe will work at zero :-). This bandwidth is mutually exclusive with the term "tuned". And if by tuned they mean low pass, then it is not a new concept since that is covered by conventional mufflers. There may be something to this new concept but until this contradiction is explained, I would hesitate to start cutting parts. Tracy On Tue, Jan 6, 2009 at 12:59 PM, Ernest Christley wrote: > Tracy Crook wrote: > >> Interesting stuff Ernest, Hope this turns up some good results. >> >> I haven't had time to really go into muffler theory so I've just observed >> what the car & motorcycle makers do. Based on these observations only, >> I've concluded that unless we come up with a new concept, there is no >> substitute for size and cubic inches. >> > The phononic devices ARE a new concept. Most of the data I've been able to > find has been abstracts of peer-review research publications. The three > links I provided earlier are the only publicly available data I've turned > up. > Even still, conceptually it's a fairly simple construct. The devilish > part, as Bill alluded to, is that it has to be tuned. The papers I've read > lead me to believe that I have some idea of the magnitude of the dimensions > necessary, and I've sketched out a way to run a lot of tests of different > configurations easily. Nothin' left to do but the doin'. 8*) > > > -- > Homepage: http://www.flyrotary.com/ > Archive and UnSub: > http://mail.lancaironline.net:81/lists/flyrotary/List.html > ------=_Part_207957_30902834.1231350637332 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline Agreed, this is definitely a new concept and I hope it works.

The only thing that bothers me is that, as you pointed out, the bandwidth needed for attenuation is about 0 to 12 Khz.  That represents MANY octaves even if we bump the lower limit to a realistic number ( only a closed pipe will work at zero :-).  This bandwidth is mutually exclusive with the term "tuned".  And if by tuned they mean low pass, then it is not a new concept since that is covered by conventional mufflers.  There may be something to this new concept but until this contradiction is explained, I would hesitate to start cutting parts.

Tracy


On Tue, Jan 6, 2009 at 12:59 PM, Ernest Christley <echristley@nc.rr.com> wrote:
Tracy Crook wrote:
Interesting stuff Ernest,  Hope this turns up some good results.

I haven't had time to really go into muffler theory so I've just observed what the car & motorcycle makers do.  Based on these observations only,  I've concluded that unless we come up with a new concept, there is no substitute for size and cubic inches.  
The phononic devices ARE a new concept.  Most of the data I've been able to find has been abstracts of peer-review research publications.  The three links I provided earlier are the only publicly available data I've turned up.
Even still, conceptually it's a fairly simple construct.  The devilish part, as Bill alluded to, is that it has to be tuned.  The papers I've read lead me to believe that I have some idea of the magnitude of the dimensions necessary, and I've sketched out a way to run a lot of tests of different configurations easily.  Nothin' left to do but the doin'.  8*)

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