X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from EXHUB003-3.exch003intermedia.net ([207.5.74.110] verified) by logan.com (CommuniGate Pro SMTP 5.2.11) with ESMTPS id 3429850 for flyrotary@lancaironline.net; Fri, 16 Jan 2009 13:58:50 -0500 Received-SPF: none receiver=logan.com; client-ip=207.5.74.110; envelope-from=jwhaley@datacast.com Received: from EXVMBX003-5.exch003intermedia.net ([207.5.74.45]) by EXHUB003-3.exch003intermedia.net ([207.5.74.110]) with mapi; Fri, 16 Jan 2009 10:58:01 -0800 From: Jeff Whaley To: Rotary motors in aircraft Date: Fri, 16 Jan 2009 10:58:10 -0800 Subject: RE: [FlyRotary] another Muffler Thread-Topic: [FlyRotary] another Muffler Thread-Index: Acl4BLJnU4MNt8+ESfWbRbeL7YzbXAAB4Acw Message-ID: References: In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: acceptlanguage: en-US Content-Type: multipart/alternative; boundary="_000_C03ABB0A7362B84BB53D544B3C305E0ED1364158E8EXVMBX0035exc_" MIME-Version: 1.0 --_000_C03ABB0A7362B84BB53D544B3C305E0ED1364158E8EXVMBX0035exc_ Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Steve, I don't see anything in your muffler that muffles ... it looks like = an expansion chamber? Jeff From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Beh= alf Of sboese Sent: Friday, January 16, 2009 12:57 PM To: Rotary motors in aircraft Subject: [FlyRotary] another Muffler The following muffler description is provided purely as another data point = in the muffler discussion. I would suspect that not many of you would be i= nterested in it due to its large size and external mounting. I have had go= od service from it so far and it fits somewhat into my loosely interpreted = Navy F6F Hellcat inverted paint scheme as a bomb. The materials of construction are 0.032" thick 304 SS and the design is bas= ed on data in NACA Report 1192. The weight is 9.6 lb and the diameter is 6= .25 inches. A SS heat shield is also installed between the muffler and the= fuselage belly. I have about 100 hours on this installation with no signs= of deterioration of the muffler. The engine is NA with exhaust splitters = and is operated normally at density altitudes above 7000 ft which limits ma= x power, although several hours of max power operation at DA lower than 500= 0 ft have not damaged this muffler so far. I have been told that from the ground, the primary source of noise for my p= lane is the propeller. I have landed with a C172 following me in the patte= rn and observers told me that they did not know I was there until I taxied = in since they only heard the C172. I have no quantitative data on the nois= e characteristics of my muffler system. Inside the cockpit, the noise leve= l goes from reasonable to unbearable if the muffler is removed. This is pu= rely subjective, of course. Not shown in the "muffler parts" image are three 1" x 1" angles made from t= he same material as the shell that connect the rear of the internal center = tube to the front of the rear cone section. The round flange in the center= of the internal tube is a push fit in the shell and is not fastened direct= ly to the shell. A down turn also has been added to the outlet of the rear= cone section. From data in the "muffler test chart" image, the speed penalty of the muffl= er is about 3 kt. The "muffler in flight" photo may be of interest in that it shows the heat = distribution in the muffler with the dark areas being hotter. This image i= s not current since the lower cowling has been modified and the engine cool= ing air outlet is now much smaller than shown in this photo. Steve Boese RV6A, 1986 13B NA, EC2, RD1A --_000_C03ABB0A7362B84BB53D544B3C305E0ED1364158E8EXVMBX0035exc_ Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

Steve, I don’t see anything in your muffler that muffl= es … it looks like an expansion chamber?

Jeff

 

From: Rotary motors= in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of sboese Sent: Friday, January 16, 2009 12:57 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] another Muffler

 

 

The following muffler description is provided purely as another data point in the muffler discussion.  I would suspect that not many o= f you would be interested in it due to its large size and external mounting.  I have had good service from it so far and it fits somewhat into my loosely interpreted Navy F6F Hellcat inverted paint scheme as a bom= b.

 

The materials of construction are 0.032” thick 304 SS and= the design is based on data in NACA Report 1192.  The weight is 9.6 lb and= the diameter is 6.25 inches.  A SS heat shield is also installed between t= he muffler and the fuselage belly.  I have about 100 hours on this instal= lation with no signs of deterioration of the muffler.  The engine is NA with exhaust splitters and is operated normally at density altitudes above 7000 = ft which limits max power, although several hours of max power operation at DA lower than 5000 ft have not damaged this muffler so far.<= /p>

 

I have been told that from the ground, the primary source of no= ise for my plane is the propeller.  I have landed with a C172 following me= in the pattern and observers told me that they did not know I was there until = I taxied in since they only heard the C172.  I have no quantitative data= on the noise characteristics of my muffler system.  Inside the cockpit, t= he noise level goes from reasonable to unbearable if the muffler is removed.&n= bsp; This is purely subjective, of course. 

 

Not shown in the “muffler parts” image are three 1&= #8221; x 1” angles made from the same material as the shell that connect the rear of the inter= nal center tube to the front of the rear cone section.  The round flange i= n the center of the internal tube is a push fit in the shell and is not faste= ned directly to the shell.  A down turn also has been added to the outlet = of the rear cone section.

 

From data in the “muffler test chart” image, the sp= eed penalty of the muffler is about 3 kt.

 

The “muffler in flight” photo may be of interest in= that it shows the heat distribution in the muffler with the dark areas being hotter. = ; This image is not current since the lower cowling has been modified and the engine cooling air outlet is now much smaller than shown in this photo.

 

Steve Boese

RV6A, 1986 13B NA, EC2, RD1A

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