X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from [129.116.87.142] (HELO MAIL01.austin.utexas.edu) by logan.com (CommuniGate Pro SMTP 5.0.3) with ESMTP id 872766 for flyrotary@lancaironline.net; Mon, 12 Dec 2005 16:31:47 -0500 Received-SPF: none receiver=logan.com; client-ip=129.116.87.142; envelope-from=mark.steitle@austin.utexas.edu X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 Content-class: urn:content-classes:message MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----_=_NextPart_001_01C5FF63.5A6B6F51" Subject: Spiral Flow Muffler Insert Test Results Date: Mon, 12 Dec 2005 15:31:03 -0600 Message-ID: <87DBA06C9A5CB84B80439BA09D86E69E0335208C@MAIL01.austin.utexas.edu> X-MS-Has-Attach: X-MS-TNEF-Correlator: Thread-Topic: Spiral Flow Muffler Insert Test Results Thread-Index: AcX/Y1o3MAvuJVEDS36+wwIPzOvDZQ== From: "Mark R Steitle" To: "Rotary motors in aircraft" This is a multi-part message in MIME format. ------_=_NextPart_001_01C5FF63.5A6B6F51 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable Well, I ran my 20B on Saturday, with and without the spiral-flow muffler insert, and took some sound measurements. It looks like its good for about a 14db reduction at 3-4000 rpm. Keep in mind that the a/c was positioned between two rows of hangars and since I have a prop now, a good part of the db numbers represent prop noise. Measurements were taken at the front, rear, and at the wing tips, which is about 16' from the exhaust for the left wing and 18' for the right wing. Never the less, I am pleased with the results. After we finished the initial runs, I removed the insert and inspected it for damage... there was none. I have 10 hours of easy running on it at this point. The real test is yet to come. =20 Test data below... Mark S. =20 =20 R Wing=20 =20 =20 =20 =20 =20 =20 =20 RPMS Mode A Mode C Muffler Insert 1200 81 90 Y 1600 84 93 Y 4000 97 102 Y =20 Front =20 =20 =20 =20 =20 =20 =20 RPMS Mode A Mode C Muffler Insert 1200 80 92 Y 1600 83 94 Y 3000 96 100 Y 4000 100 100 Y 1600 94 90 N 4000 111 114 N =20 Left Wing =20 =20 =20 =20 =20 =20 =20 RPMS Mode A Mode C Muffler Insert 1200 82 92 Y 1600 83 93 Y 3000 90 102 Y 4000 96 104 Y 4000 111 114 N =20 Rear =20 =20 =20 =20 =20 =20 =20 RPMS Mode A Mode C Muffler Insert 1200 82 93 Y 1600 83 104 Y 3000 96 112 Y =20 ------_=_NextPart_001_01C5FF63.5A6B6F51 Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable

Well, I ran my 20B on Saturday, with and without the spiral-flow muffler insert, and took some sound measurements. It = looks like its good for about a 14db reduction at 3-4000 rpm. Keep in = mind that the a/c was positioned between two rows of hangars and since I have a = prop now, a good part of the db numbers represent prop noise. Measurements = were taken at the front, rear, and at the wing tips, which is about 16’ = from the exhaust for the left wing and 18’ for the right wing. = Never the less, I am pleased with the results. After we finished the initial = runs, I removed the insert and inspected it for damage… there was = none. I have 10 hours of easy running on it at this point. The real test = is yet to come.

Test data below…

Mark S.

R Wing

RPMS	Mode = A	Mode = C	Muffler = Insert
1200	81<= /p>	90<= /p>	Y
1600	84<= /p>	93<= /p>	Y
4000	97<= /p>	102=	Y

Front

RPMS	Mode = A	Mode = C	Muffler = Insert
1200	80<= /p>	92<= /p>	Y
1600	83<= /p>	94<= /p>	Y
3000	96<= /p>	100=	Y
4000	100=	100=	Y
1600	94<= /p>	90<= /p>	N
4000	111=	114=	N

Left Wing

RPMS	Mode = A	Mode = C	Muffler = Insert
1200	82<= /p>	92<= /p>	Y
1600	83<= /p>	93<= /p>	Y
3000	90<= /p>	102=	Y
4000	96<= /p>	104=	Y
4000	111=	114=	N

Rear

RPMS	Mode = A	Mode = C	Muffler = Insert
1200	82<= /p>	93<= /p>	Y
1600	83<= /p>	104=	Y
3000	96<= /p>	112=	Y

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