X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from fmailhost03.isp.att.net ([207.115.11.53] verified) by logan.com (CommuniGate Pro SMTP 5.2.16) with ESMTP id 3877596 for flyrotary@lancaironline.net; Wed, 07 Oct 2009 08:01:55 -0400 Received-SPF: none receiver=logan.com; client-ip=207.115.11.53; envelope-from=keltro@att.net DKIM-Signature: v=1; q=dns/txt; d=att.net; s=dkim01; i=keltro@att.net; a=rsa-sha256; c=relaxed/relaxed; t=1254916915; h=Content-Type: MIME-Version:In-Reply-To:Message-Id:Date:Subject:To:From; bh=yPokoI GxBKPt4p2KKVEgd/3jEHpDaOuh6YIbivTI3zg=; b=f1AcQlH/B5nD12+eNELK6IEqs 5iIV1nM6Lh+G6VmT4gcglrWahUbZWGjQ0AbEwqoFMp5sJxwgKMwNs9mKGQHZg== Received: from fwebmail13.isp.att.net ([204.127.221.113]) by isp.att.net (frfwmhc03) with SMTP id <20091007120120H0300pphdee>; Wed, 7 Oct 2009 12:01:20 +0000 X-Originating-IP: [204.127.221.113] Received: from [208.114.33.94] by fwebmail13.isp.att.net; Wed, 07 Oct 2009 12:01:19 +0000 From: "Kelly Troyer" To: "Rotary motors in aircraft" Subject: Re: Absorbtion muffler Date: Wed, 07 Oct 2009 12:01:19 +0000 Message-Id: <100720091201.25003.4ACC830F000127D4000061AB22218683269B0A02D29B9B0EBF019D9B040A05@att.net> In-Reply-To: X-Mailer: AT&T Message Center Version 1 (Mar 2 2009) X-Authenticated-Sender: a2VsdHJvQGF0dC5uZXQ= MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="NextPart_Webmail_9m3u9jl4l_25003_1254916879_0" --NextPart_Webmail_9m3u9jl4l_25003_1254916879_0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Mike, Were you able to determine the approx diameter and length of the expansio= n chamber=20 ahead of the perforated tube ??................. -- Kelly Troyer=20 "Dyke Delta"_13B ROTARY Engine=20 "RWS"_RD1C/EC2/EM2=20 "Mistral"_Backplate/Oil Manifold=20 -------------- Original message from "Mike Wills" : -----= ---------=20 Ed, I assume all of your attempts were built along the lines of a typical glas= spak or "Swiss muffler" with packing either wrapped or stuffed around some = sort of perf tube? The type of muffler I'm considering is the one I mentioned having seen ove= r the weekend. The reasons I think it might work and live behind the rotary= are: 1) Lots of internal volume. The muffler I saw was at least 8 feet long. 2) The perforated tube down the center ran the full length of the muffler p= roviding lots of perforations to dissipate the exhaust energy. 3) The muffler introduces fresh air into the muffler to cool the exhaust. I have no idea if it will really work and I'm not rushing into anything. Bu= t I went out to Miramar and watched the airplane depart on sunday. It was v= irtually silent. Mike ----- Original Message -----=20 From: Ed Anderson=20 To: Rotary motors in aircraft=20 Sent: Tuesday, October 06, 2009 3:29 AM Subject: [FlyRotary] Absorbtion muffler [FlyRotary] Re: engine runup video Good luck, Mike, on the absorption muffler with a rotary. I have tried a n= umber of different approaches including mufflers with ceramic packing that = can withstand 2000F+. The heat is no problem, the problem is the exhaust s= hock wave pulverizes the ceramic/fiberglass/stainless steel/etc into small = pieces in a relative short time. Its true they were good in suppressing so= und while they lasted, but two weeks =E2=80=93 1 month was about the limit. =20 I still dream of doing a remake of a muffler design I came up with which ha= d 3=E2=80=9D 1/8=E2=80=9D stainless steel discs (about 4-5) in a 36=E2=80= =9D tube. The disc were slotted and =E2=80=9Cblades=E2=80=9D bent until th= e disc looked a bit like a fan. The blades were bent at an approx 45 deg a= ngle. If you looked down the tube with the disc in it all you saw was soli= d metal =E2=80=93 however the blades provide room for exhaust gas to flow a= round them. The theory was the shock wave would see basically a solid disc= and reflect some/most of its energy back and forth between discs, whereas= the gas could more or less freely flow around and through the blades. =20 The concept worked well in that my hangar neighbors were all remarking how = quite the engine sounded and I could still get a static rpm of 6000.=20 =20 The problem was I am not a welder and while I had the disc clamped with Jam= nuts to a SS thread rod through their center =E2=80=93 it was not sufficie= nt to keep the exhaust from loosening the nuts and causing the discs to spi= n like a turbine wheel. IF I could have welded the tips of the blades to t= he tube then it may have been viable. But, not a welder and got tire of me= ssing with exhaust so I hung two Hushpower mufflers and went flying. =20 Ed =20 Ed Anderson Rv-6A N494BW Rotary Powered --NextPart_Webmail_9m3u9jl4l_25003_1254916879_0 Content-Type: multipart/related; boundary="NextPart_Webmail_9m3u9jl4l_25003_1254916879_1" --NextPart_Webmail_9m3u9jl4l_25003_1254916879_1 Content-Type: text/html; charset="utf-8" Content-Transfer-Encoding: quoted-printable
Mike,
  Were you able to determine the approx diameter and length of th= e expansion chamber
ahead of the perforated tube ??.................
--
Kelly Troyer
"Dyke Delta"_1= 3B ROTARY Engine
"RWS"_RD1C/EC2/EM2
"Mistral"_Backplate/Oil Manifol= d
-------------- Original message from "Mike Wills" <rv-4mi= ke@cox.net>: --------------

Ed,
 
 I assume all of your attempts were b= uilt along the lines of a typical glasspak or "Swiss muffler" with packing = either wrapped or stuffed around some sort of perf tube?
 
 The type of muffler I'm considering = is the one I mentioned having seen over the weekend. The reasons I think it= might work and live behind the rotary are:
1) Lots of internal volume. The muffler I = saw was at least 8 feet long.
2) The perforated tube down the center ran= the full length of the muffler providing lots of perforations to dissipate= the exhaust energy.
3) The muffler introduces fresh air into t= he muffler to cool the exhaust.
 
I have no idea if it will really work and = I'm not rushing into anything. But I went out to Miramar and watched the ai= rplane depart on sunday. It was virtually silent.
 
Mike
----- Original Message -----
= From: Ed Anderson
Sent: Tuesday, October 06, 2009 3:29= AM
Subject: [FlyRotary] Absorbtion muff= ler [FlyRotary] Re: engine runup video

Good luck, Mike, on t= he absorption muffler with a rotary.  I have tried a number of differe= nt approaches including mufflers with ceramic packing that can withstand 20= 00F+.  The heat is no problem, the problem is the exhaust shock wave p= ulverizes the ceramic/fiberglass/stainless steel/etc into small pieces in a= relative short time.  Its true they were good in suppressing sound wh= ile they lasted, but two weeks =E2=80=93 1 month was about the limit.<= /o:p>

 

I still dream of doin= g a remake of a muffler design I came up with which had 3=E2=80=9D 1/8=E2= =80=9D stainless steel discs (about 4-5) in a 36=E2=80=9D tube.  The d= isc were slotted and =E2=80=9Cblades=E2=80=9D bent until the disc looked a = bit like a fan.  The blades were bent at an approx 45 deg angle. = If you looked down the tube with the disc in it all you saw was solid meta= l =E2=80=93 however the blades provide room for exhaust gas to flow around = them.  The theory was the shock wave would see basically a solid disc = and reflect some/most of its energy back and forth between discs,  whe= reas the gas could more or less freely flow around and through the blades.<= o:p>

 

The concept worked we= ll in that my hangar neighbors were all remarking how quite the engine soun= ded and I could still get a  static rpm of 6000.

 

The problem was I am = not a welder and while I had the disc clamped with Jam nuts to a SS thread = rod through their center =E2=80=93 it was not sufficient to keep the exhaus= t from loosening the nuts and causing the discs to spin like a turbine whee= l.  IF I could have welded the tips of the blades to the tube then it = may have been viable.  But, not a welder and got tire of messing with = exhaust so I hung two Hushpower mufflers and went flying.=

 

Ed<= /FONT>

 

Ed Anderson

Rv-6A N494BW Rotary Powered

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