X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mail-iw0-f180.google.com ([209.85.214.180] verified) by logan.com (CommuniGate Pro SMTP 5.3.8) with ESMTP id 4389866 for flyrotary@lancaironline.net; Mon, 12 Jul 2010 11:59:20 -0400 Received-SPF: pass receiver=logan.com; client-ip=209.85.214.180; envelope-from=msteitle@gmail.com Received: by iwn8 with SMTP id 8so4506099iwn.25 for ; Mon, 12 Jul 2010 08:58:43 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:received:in-reply-to :references:date:message-id:subject:from:to:content-type; bh=T5Bhd8NyuWNWlLSKdPBvEb8mttLJoOIViYUc1LbSf8o=; b=r5DS+ei1Zqed0XlBA2p7psUsRsSvgdWQ/6Fak2VHsjHxQ1O35LhJtF4oWiXW4q4qjS JULGLi1BvpyRXe8INmQzM0b1AH4s+Ieo5OX6N9wqZSE9ZUqdVpWKojXKOKtxj3j4AxGt XbMUZsdGYqx121OCf+XxV9NU4mp8HR/KTaiE8= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; b=FZkcdHgI+DhUfy50CacjBYx+SP0YU1/6BxpYkJ1hxU3RWKVaxZEV+s9ZwuTgMyCxkO gPTrlPWuvVK1Q5oiwXRBgDs4gfnz8aEvT7kdGsoYs8HgxguPdH2cFrNVlYgIbuXSzK+Y PAXKVvMcOrh0kdg625gVBJFxlEg6kPEx2lV0k= MIME-Version: 1.0 Received: by 10.231.191.142 with SMTP id dm14mr13794867ibb.74.1278950322389; Mon, 12 Jul 2010 08:58:42 -0700 (PDT) Received: by 10.231.183.138 with HTTP; Mon, 12 Jul 2010 08:58:42 -0700 (PDT) In-Reply-To: References: Date: Mon, 12 Jul 2010 10:58:42 -0500 Message-ID: Subject: Re: [FlyRotary] Re: Mufflers From: Mark Steitle To: Rotary motors in aircraft Content-Type: multipart/alternative; boundary=0016363b906ea6c3a2048b32d309 --0016363b906ea6c3a2048b32d309 Content-Type: text/plain; charset=ISO-8859-1 Dwayne, I added a cone-shaped 3" to 2.5" reducer to the exit of my DNA muffler to try and quiet it down a bit. I think it was Tracy that recommended that. It did work to reduce the noise a little, but at the expense of HP. I left it on until I replaced the whole thing with a tangential muffler. I looked up the "pre-silencer" muffler on the Mazdatrix web site. Their site is running real slow at the moment, and most pages didn't load at all. I was able to get to their exhaust system information page. It wasn't that much help as it is geared towards automotive applications. Mark On Mon, Jul 12, 2010 at 9:00 AM, Dwayne Parkinson wrote: > Mark, > > If' you're up for more experimenting, try a conical "tail pipe" on whatever > muffler you have now. The sound waves will behave just as if you held a > cone up to your ear. More sound will be coming out of a smaller hole but > due to the shape of the cone I believe some of the sound will run into > itself and cancel itself out forming a mildly effective second muffler. I > haven't tested this so I don't know if this works. If you have a DB meter > (which I don't) you can easily test the theory to see if it's worth your > time though. Take a tube from the Christmas wrapping paper, cram a kitchen > timer or anything else that makes a constant noise in one end and hold your > DB meter just outside the other end and then measure the DB of the noise in > a straight pipe. If you want to be really clever, record your rotary engine > and replay that sound. Now cut sections out of the last 8 or 10" of the > tube and form it into a cone. See if there's a DB drop. Play around with > different shapes of cones and see if it makes a difference. > > When I mention this, most people immediately think BACK PRESSURE!!! If > you're measuring back-pressure you *should* see no change. Bernoulli's > principle should apply to the exhaust gas and it will merely speed up and > exit faster just like it does with the leaf blower attachment on a Shop Vac. > There are issues like boundary layers building up and the fact that the > muffler pulses aren't a constant pressure, but I believe that shouldn't be > an issue based on the fact that there's really no such thing as a true > constant pressure and the rotary at any reasonably high RPM will produce a > relatively constant flow of exhaust gas. > > Good luck. Let me know if you try it and how it goes. > > Thanks, > > Dwayne > > > ------------------------------ > *From:* Mark Steitle > *To:* Rotary motors in aircraft > *Sent:* Fri, July 9, 2010 4:44:19 PM > *Subject:* [FlyRotary] Re: Mufflers > > Steve, > > Yes, that would be me, "Mr. Muffler" himself. The Moroso style muffler > didn't muffle very well and it kept melting the bolt holding the baffle in > place. I finally went with a SS bolt which didn't melt. In an effort to > find something that wasn't as noisy, I discarded it for the DNA muffler > which wasn't much quieter, but it survived the harsh rotary environment > better than anything else I had tried up to that point. I'm now running an > inconel 625 tangential muffler, which is the best as for noise attenuation > I've used to date. The only problem is that I suspect I'm losing hp due to > excess back pressure. But at leaast I can hear to talk on the radio. Its > my opinion at this stage of the game that the best muffler is a turbo. At > least you achieve a fairly quiet exhaust note, and get some extra hp too. > > Mark S. > > On Fri, Jul 9, 2010 at 8:15 AM, Stephen Thomas wrote: > >> I remember some discussion a while back regarding the concept of the >> Moroso spin muffler. See: >> >> http://moroso.com/catalog/categorydisplay.asp?CatCode=35054 >> >> Anyone out there still using it? What were the conclusions of those who >> tried it? I know someone made one from scratch. I have a small Burns >> Stainless muffler that is totally inadequate in terms of sound attenuation. >> So, I'm looking for alternatives and remember a lot of discussion regarding >> this device. >> >> >> Steve Thomas >> ________________________________________________________________________ >> >> >> >> >> -- >> Homepage: http://www.flyrotary.com/ >> Archive and UnSub: >> http://mail.lancaironline.net:81/lists/flyrotary/List.html >> > > > --0016363b906ea6c3a2048b32d309 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable
Dwayne,
=A0
I added a cone-shaped 3" to 2.5" reducer to the exit of my D= NA muffler to try and quiet it down a bit.=A0 I think it was Tracy that rec= ommended that.=A0 It did work to reduce the noise a little, but at the expe= nse of HP.=A0 I left it on until I replaced the whole thing with a tangenti= al muffler.=A0 =A0
=A0
I looked up the "pre-silencer" muffler on the Mazdatrix web = site.=A0 Their site is running real slow at the moment, and most pages didn= 't load at all.=A0 I=A0was able to get to their exhaust system informat= ion page.=A0 It wasn't that much help as it is geared towards automotiv= e applications.=A0=A0
=A0
Mark=A0

On Mon, Jul 12, 2010 at 9:00 AM, Dwayne Parkinso= n <dwayne= parkinson@yahoo.com> wrote:
Mark,

If' you're up for more experimenting, try a conical "tail= pipe" on whatever muffler you have now. =A0The sound waves will behav= e just as if you held a cone up to your ear. =A0More sound will be coming o= ut of a smaller hole but due to the shape of the cone I believe some of the= sound will run into itself and cancel itself out forming a mildly effectiv= e second muffler. =A0I haven't tested this so I don't know if this = works. =A0If you have a DB meter (which I don't) you can easily test th= e theory to see if it's worth your time though. =A0Take a tube from the= Christmas wrapping paper, cram a kitchen timer or anything else that makes= a constant noise in one end and hold your DB meter just outside the other = end and then measure the DB of the noise in a straight pipe. =A0If you want= to be really clever, record your rotary engine and replay that sound. =A0N= ow cut sections out of the last 8 or 10" of the tube and form it into = a cone. =A0See if there's a DB drop. =A0Play around with different shap= es of cones and see if it makes a difference.

When I mention this, most people immediately think BACK PRESSURE!!! = =A0If you're measuring back-pressure you should=A0see no change.= =A0Bernoulli's principle should apply to the exhaust gas and it will m= erely speed up and exit faster just like it does with the leaf blower attac= hment on a Shop Vac. =A0There are issues like boundary layers building up a= nd the fact that the muffler pulses aren't a constant pressure, but I b= elieve that shouldn't be an issue based on the fact that there's re= ally no such thing as a true constant pressure and the rotary at any reason= ably high RPM will produce a relatively constant flow of exhaust gas.

Good luck. =A0Let me know if you try it and how it goes.

Thanks,

Dwayne

<= br>
From: Mark Steitle <msteitle@gmail.com&= gt;
To: Rotary motors in= aircraft <flyrotary@lancaironline.net>
Sent: Fri, July 9, 2010 4:4= 4:19 PM
Subject: [FlyRot= ary] Re: Mufflers

Steve,=A0=20

Yes, that would be me, "Mr. Muffler" himself. =A0The Moroso = style muffler didn't muffle very well and it kept melting the bolt hold= ing the baffle in place. =A0I finally went with a SS bolt which didn't = melt. =A0In an effort to find something that wasn't as noisy, I discard= ed it for the DNA muffler which wasn't much quieter, but it survived th= e harsh rotary environment better than anything else I had tried up to that= point. =A0I'm now running an inconel 625 tangential muffler, which is = the best as for noise attenuation I've used to date. =A0The only proble= m is that I suspect I'm losing hp due to excess back pressure. =A0But a= t leaast I can hear to talk on the radio. =A0Its my opinion at this stage o= f the game that the best muffler is a turbo. =A0At least you achieve a fair= ly quiet exhaust note, and get some extra hp too.

Mark S.

On Fri, Jul 9, 2010 at 8:15 AM, Stephen Thomas <= span dir=3D"ltr"><glasair2@me.com> wrote:
I remember some discussion a whi= le back regarding the concept of the Moroso spin muffler. =A0See:

http://moroso.com/catalog/categorydisplay.asp?CatCode= =3D35054

Anyone out there still using it? =A0What were the conclusions of those = who tried it? =A0I know someone made one from scratch. =A0I have a small Bu= rns Stainless muffler that is totally inadequate in terms of sound attenuat= ion. =A0So, I'm looking for alternatives and remember a lot of discussi= on regarding this device.


Steve Thomas
___________________________________________________= _____________________




--
Homepage: =A0http= ://www.flyrotary.com/
Archive and UnSub: =A0 http://mail.lancaironline.net:81= /lists/flyrotary/List.html



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