X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from imr-ma03.mx.aol.com ([64.12.206.41] verified) by logan.com (CommuniGate Pro SMTP 5.4c3j) with ESMTP id 4952024 for flyrotary@lancaironline.net; Wed, 20 Apr 2011 10:29:07 -0400 Received-SPF: pass receiver=logan.com; client-ip=64.12.206.41; envelope-from=Lehanover@aol.com Received: from imo-ma02.mx.aol.com (imo-ma02.mx.aol.com [64.12.78.137]) by imr-ma03.mx.aol.com (8.14.1/8.14.1) with ESMTP id p3KESPGo029153 for ; Wed, 20 Apr 2011 10:28:26 -0400 Received: from Lehanover@aol.com by imo-ma02.mx.aol.com (mail_out_v42.9.) id q.e3c.e6abbe7 (45455) for ; Wed, 20 Apr 2011 10:28:23 -0400 (EDT) Received: from magic-d22.mail.aol.com (magic-d22.mail.aol.com [172.19.155.138]) by cia-mc06.mx.aol.com (v129.10) with ESMTP id MAILCIAMC061-b18f4daeed87c4; Wed, 20 Apr 2011 10:28:23 -0400 From: Lehanover@aol.com Message-ID: Date: Wed, 20 Apr 2011 10:28:23 EDT Subject: Re: [FlyRotary] Re: Burns Stainless Muffler Failure To: flyrotary@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="part1_ad7af.41867327.3ae04787_boundary" X-Mailer: AOL 9.6 sub 130 X-AOL-IP: 173.88.24.45 X-Spam-Flag:NO X-AOL-SENDER: Lehanover@aol.com --part1_ad7af.41867327.3ae04787_boundary Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit I made one of those with a house jack tube for the center tube out of carbon steel. The tube was 1/8" wall. I drilled a bunch of 1/2" holes near the front and 5/32" holes near the end. It worked pretty well, but lasted only 9 weekends before the center tube melted loose. External tube in .062" stayed just fine. You can do a lot of heat, or a lot of pounding, but not both. Nothing flat will survive. Lynn E. Hanover In a message dated 4/20/2011 9:59:23 A.M. Atlantic Daylight Time, eanderson@carolina.rr.com writes: Hi Thomas, Thanks for the photo. The exhaust pulse from the rotary is just incredible powerful. Any flat surface perpendicular to the pulse (such as the end of you muffler), appears to be doomed to fatigue failure from the pounding of the pulse. I once squished the tips of 2" dia SS steel tubes together and drilled holes to make a "fishtail" sound suppressor. After a 30 min flight, I came back to find chunks of the SS tube missing where the pulse had hammer and fatigued the tips during that short flight. Rather than a flat surface, a cone or angle surface which deflects some of the pulse energy appears to be required for longer term survival. Better luck on your next choice Ed --part1_ad7af.41867327.3ae04787_boundary Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable

I made one of those with a house jack tube for the center tube out of= =20 carbon steel. The tube was 1/8" wall. I drilled a bunch of 1/2" holes near= the=20 front and 5/32" holes near the end. It worked pretty well, but lasted only= 9=20 weekends before the center tube melted loose. External tube in .062" staye= d just=20 fine. You can do a lot of heat, or a lot of pounding, but not both. Nothin= g flat=20 will survive.

Lynn E. Hanover

In a message dated 4/20/2011 9:59:23 A.M. Atlantic Daylight Time,=20 eanderson@carolina.rr.com writes:

Hi=20 Thomas,

Thanks for the photo.

The exhaust pulse from the= rotary=20 is just incredible powerful. Any flat
surface perpendicular to= the=20 pulse (such as the end of you muffler), appears
to be doomed to fati= gue=20 failure from the pounding of the pulse.

I once squished the tips= of 2"=20 dia SS steel tubes together and drilled
holes to make a "fishtail"= sound=20 suppressor. After a 30 min flight, I came
back to find chunks= of the=20 SS tube missing where the pulse had hammer and
fatigued the tips dur= ing=20 that short flight.

Rather than a flat surface, a cone or angle su= rface=20 which deflects some of
the pulse energy appears to be required for= longer=20 term survival.

Better luck on your next=20 choice

Ed

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