X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mail-pz0-f181.google.com ([209.85.222.181] verified) by logan.com (CommuniGate Pro SMTP 5.2.16) with ESMTP id 3839230 for flyrotary@lancaironline.net; Sun, 06 Sep 2009 16:40:03 -0400 Received-SPF: pass receiver=logan.com; client-ip=209.85.222.181; envelope-from=wdleonard@gmail.com Received: by pzk11 with SMTP id 11so635373pzk.3 for ; Sun, 06 Sep 2009 13:39:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:in-reply-to:references :date:message-id:subject:from:to:content-type; bh=qK9yZ92oS3ZxYaMm0cifd8ZesxaoB223X5swX65jcJ4=; b=FlwmJTV2Va1kvt1Rf74PQyoOUeZgz7kf/Lyi2revDYy3fSo3xUPoKZnfS1erTvvh8h YwDnl/L1jcWmwEqybKkycuW+EGidOTuKZBFZ3vFpAeptDYOBXzi/j1fuGRcCgfGg/91H 6znlMHZyg1GYAJTnuecC7cheT5u924VlPsuRM= 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=BpAEPGgs+ppoVEtrEMb7omQe4TmatXrwRujfJAhXmGPoWZm7I56OVQsmAfjDpNsYeI 6pF156IUPKj3bLHcB7amdaUGol474edjb7JB3c7z3klYZU1PBIPryS3aOWG2o5B1Sumu FlzEcQ7TUgiM+s9OrWxjjgofrBZITmdQZL5Ms= MIME-Version: 1.0 Received: by 10.141.3.4 with SMTP id f4mr3240930rvi.163.1252269568639; Sun, 06 Sep 2009 13:39:28 -0700 (PDT) In-Reply-To: References: Date: Sun, 6 Sep 2009 13:39:28 -0700 Message-ID: <1c23473f0909061339x56be4c7sad1620d2a5a374ae@mail.gmail.com> Subject: Re: [FlyRotary] Re: Muffling/ Morroso update From: David Leonard To: Rotary motors in aircraft Content-Type: multipart/alternative; boundary=000e0cd11362cd45140472eeba14 --000e0cd11362cd45140472eeba14 Content-Type: text/plain; charset=ISO-8859-1 Dont really NEED to. I flew quite a while without a muffler at all. But the turbo is not as good as a muffler and it is more enjoyable when quieter. The wife and dog particularly do better when it is quieter. -- David Leonard Turbo Rotary RV-6 N4VY http://N4VY.RotaryRoster.net http://RotaryRoster.net On Sun, Sep 6, 2009 at 12:02 PM, Bill Bradburry wrote: > David, > > Do you need to muffle the turbo? > > Bill B > > > ------------------------------ > > *From:* Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] *On > Behalf Of *David Leonard > *Sent:* Sunday, September 06, 2009 2:47 PM > *To:* Rotary motors in aircraft > *Subject:* [FlyRotary] Re: Muffling/ Morroso update > > > > I have been running the Morroso for the last 20 hours or so. Not sure it > is the muffler, but I have noticed a definate decrease in power. Too bad > because it did a nice job on the sound and only weighed 3 lbs. > > > > I think next I will empty out the flowmaster shell and reinstall it - then > live with the noise. Maybe put in some lava rocks if I get tired of the > noise again. Maybe try a fishmouth. > > > > -- > David Leonard > > Turbo Rotary RV-6 N4VY > http://N4VY.RotaryRoster.net > http://RotaryRoster.net > > On Sun, Sep 6, 2009 at 10:19 AM, Lynn Hanover > wrote: > > Mark/Ed/Bill, > > > > I was thinking along the same lines as Bill - that the DNA is more > restrictive resulting in richer mixtures at equivalent MAP. My home made > muffler was a copy of the Moroso spiral flow mufflers, but with a larger > center tube. With my home made muffler I can look all the way through it so > the DNA is clearly more restrictive. Which is why I'm surprised it didnt > work better. > > > > The DNA sure looks better than my home made muffler. Weld quality is great. > Time will tell how it holds up. The home made muffler was Inconel so I > expect it would be more durable in the long run. > > > > The point of something else in the airflow path limiting HP is a good > point. One of things I've noticed is that I reach max power long before I > reach max throttle. Since I'm making enough power for good performance I > wasnt too worried about this, but I am curious. Once I reach about 3/4 > throttle I'm maxed out - the last 1/4 doesnt do anything. > > > > Mike Wills > > RV-4 N144MW > > > > The first problem to overcome when muffling a rotary, is the supersonic > shock wave leaving the engine. If you can see through the muffler from end > to end, it is probable that some part of that shock wave will exit the > muffler. In order to slow the shock wave to subsonic it is required that the > muffler provide some pressure in front of, Or, to impinge on the moving wave > to slow it down. > > > > The Mazda racing muffler has an empty room at the front that allows the > shock wave to expand and drop to subsonic before muffling begins. You can > see through the Mazda muffler, but they address the supersonic problem early > in the process. They used to use lava rocks for the media, This stuff would > be turned to dust and expelled during the year, and need to be replaced. > > > > The center tube was perfed as was the front bulkhead. So pressure from the > front chamber could see the center tube cross section > > and the perfed bulkhead area. So in that regard the muffler was ineffective > if the front chaomber failed to drop the shock wave to subsonic. However it > did, and could hold the strongest Rotary to 105 dB at 50 feet. (Full > throttle at best power RPM) Probably well above 9,000 RPM. > > > > So to muffle you drop the velocity, using volume changes. By cooling the > flow, by impinging on the flow with gasses collected in the front of the > muffler and reintroduced near the end of the muffler, by using the flow to > impinge on itself with splitters or divided flow tricks and reflectors. By > absorbing the highest pressure peaks in some form of replaceable media. By > absorbing the most offensive frequencies in tuned cavities. > > > > Once the supersonic problem is delt with, conventional car mufflers are > effective. > > > > My first muffler attempt started with the center tube being from a house > jack strut. About 1/8 wall probably 1010 steel. Large diameter holes in the > first 5 inches to help replicate the Mazda cavity muffler. Then a bulkhead > with 1/4" holes. Then a space of about 4" with no holes. Then thousands (it > seemed like) of 1/8" holes in the rest of the tube length. I worked pretty > well and then melted the center tube near the front. There was no media > involved. About 30" overall. > > > > The rotary is slightly more tolorant of back pressure than is suspected, > and this may be used to impinge > > on fuffling flow. At the exhause flange, there is a negative pressure well > below ambient. A leak here draws cold air into the system and unburned fuel > ignites with a popping sound, like a 2 cycle scooter off the power. > > > > Perf tube mufflers take off the peaks and then impinge on the flow. So they > may affect tuning every where, and then change as the media melts into > little balls or is hammered to dust and leaves the muffler. > > > > It seemed to me that the Spintech was close to the best for this > application, and would like to have seen that run to destruction. > > > > Just my opinion, I could be completly wrong. > > > > Lynn E. Hanover > > > > > --000e0cd11362cd45140472eeba14 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable
Dont really NEED to.=A0 I flew quite a while without a muffler at all.= =A0 But the turbo is not as good as a muffler and it=A0is more enjoyable wh= en quieter.=A0 The wife and dog particularly do better when it is quieter.<= /div>
=A0
--
David Leonard

Turbo Rotary RV-6 N4VY
http://N4VY.RotaryRoster.net
http://RotaryRoster.net


On Sun, Sep 6, 2009 at 12:02 PM, Bill Bradburry = <bbradburr= y@bellsouth.net> wrote:

David,

Do you need to muffle the turbo?

Bill B

=A0

From: Rota= ry motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of David Leonard
Sent: Sunday, September 06,= 2009 2:47 PM
To: Rotary= motors in aircraft
Subject:= [FlyRotary] Re: Muffling/ Morroso update

= --
David Leonard

Turbo Rotary RV= -6 N4VY
http= ://N4VY.RotaryRoster.net
http://RotaryRoster.= net

lehanover@gmail.com> wrote:=

Mark/Ed/Bill,

I was thinking along the same lines as Bill - that the DNA is m= ore restrictive resulting in richer mixtures at equivalent MAP. My home mad= e muffler was a copy of the Moroso spiral flow mufflers, but with a larger = center tube. With my home made muffler I can look all the way through it so= the DNA is clearly more restrictive. Which is why I'm surprised it did= nt work better.

The DNA sure looks better than my home made muffler. Weld quali= ty is great. Time will tell how it holds up. The home made muffler was Inco= nel so I expect it would be more durable in the long run.

The point of something else in the airflow path limiting HP is = a good point. One of things I've noticed is that I reach max power long= before I reach max throttle. Since I'm making enough power for good pe= rformance I wasnt too worried about this, but I am curious. Once I reach ab= out 3/4 throttle I'm maxed out - the last 1/4 doesnt do anything.

Mike Wills

RV-4 N144MW


--000e0cd11362cd45140472eeba14--