X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from fed1rmmtao105.cox.net ([68.230.241.41] verified) by logan.com (CommuniGate Pro SMTP 5.2.16) with ESMTP id 3842028 for flyrotary@lancaironline.net; Tue, 08 Sep 2009 22:02:34 -0400 Received-SPF: none receiver=logan.com; client-ip=68.230.241.41; envelope-from=rv-4mike@cox.net Received: from fed1rmimpo01.cox.net ([70.169.32.71]) by fed1rmmtao105.cox.net (InterMail vM.8.00.01.00 201-2244-105-20090324) with ESMTP id <20090909020158.LNQM21106.fed1rmmtao105.cox.net@fed1rmimpo01.cox.net> for ; Tue, 8 Sep 2009 22:01:58 -0400 Received: from wills ([68.105.80.138]) by fed1rmimpo01.cox.net with bizsmtp id eS1w1c0052z3ATG03S1zUA; Tue, 08 Sep 2009 22:01:59 -0400 X-VR-Score: 0.00 X-Authority-Analysis: v=1.0 c=1 a=GYUE2u3J2VKmYTc9EdsA:9 a=MUwsXSmK2KA6If9T48EA:7 a=rzudd7-V73ue290ntfU_EL-TTYYA:4 a=pGLkceISAAAA:8 a=Ia-xEzejAAAA:8 a=vCtJIWKPVKvg7bTrbHoA:9 a=DkS0RRY_n9Qw6p7f2RsA:7 a=BOmCMYtyjdsRm4mA3AFxPD7572MA:4 a=MSl-tDqOz04A:10 a=EzXvWhQp4_cA:10 X-CM-Score: 0.00 Message-ID: <6D3F39EA30944E1BB1062D24975C72B8@wills> From: "Mike Wills" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Muffling Date: Tue, 8 Sep 2009 19:01:56 -0700 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0069_01CA30B6.D5E0EFB0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.5843 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.5579 This is a multi-part message in MIME format. ------=_NextPart_000_0069_01CA30B6.D5E0EFB0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable For Tracy, Can you refresh my memory on what happened with the Spintech = experiment? I seem to recall some issues with weight and drag? But I = wasnt subscribed to the list when you replaced it so I'm not sure what = happened. At this point I think I'd be willing to accept both penalties to get an = acceptible muffler. But I dont want to buy another muffler that doesnt = work any better than the one I made. Spintech wants $375 for a custom muffler made from 321 SS. The same = muffler in aluminized mild steel is $116. I'm tempted to buy the cheapie = and try it out before committing the $375. Mike Wills RV-4 N144MW=20 ----- Original Message -----=20 From: Lynn Hanover=20 To: Rotary motors in aircraft=20 Sent: Tuesday, September 08, 2009 5:39 AM Subject: [FlyRotary] Muffling The fish tail muffler has been in service for years on motorcycles and = other machines. Its poor service life behind a rotary is due to the shock wave = dropping to subsonic by applying its energy to the flat sides of the = design. It is both a rflective and an impinging design.=20 If saw cuts are made into the long axis of the fish tail shape and = bits of metal are welded in place to prevent the flexing (and fatigue = death) of the pieces, this design might be found quite effective. Years ago I tried one of the big Suitcase Flowmaster mufflers on the = racer. A reflective design and very effective. In one session of 45 = minutes, all of the baffles were hammered loose and piled up at the exit = pipe and the sides of the muffler swelled up like a giant pillow. The = reflective design was changed to an impinging design. I was far from = home at Sebring Florida so I cut open the Flowmaster and flatened the = sides. I welded the baffles back in place with more than a spot weld = here and there. I drilled through both sides behind each baffle and = installed solid 1/4" rods to keep the flat sides from spreading open = again. I moved it to the very rear of the body where the heat load would be = reduced. That muffler lasted the rest of the season. It was sinfully heavy and = really too big for anything but a big GM car, but it worked great on the = rotary.=20 The Spintech or similar I think will fill the bill. More likely a = combination of two styles, or one style behind another. Any system that = does not include equal length headers leave a bunch of HP on the table.=20 Lynn E. Hanover ------=_NextPart_000_0069_01CA30B6.D5E0EFB0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
For Tracy,
 
 Can you refresh my memory on what = happened=20 with the Spintech experiment? I seem to recall some issues with weight = and drag?=20 But I wasnt subscribed to the list when you replaced it so I'm not sure = what=20 happened.
 
 At this point I think I'd be = willing to=20 accept both penalties to get an acceptible muffler. But I dont want to = buy=20 another muffler that doesnt work any better than the one I = made.
 
 Spintech wants $375 for a custom = muffler made=20 from 321 SS. The same muffler in aluminized mild steel is $116. I'm = tempted to=20 buy the cheapie and try it out before committing the $375.
 
Mike Wills
RV-4 N144MW 
----- Original Message -----
From:=20 Lynn=20 Hanover
Sent: Tuesday, September 08, = 2009 5:39=20 AM
Subject: [FlyRotary] = Muffling

The fish tail muffler has been in service for years on = motorcycles and=20 other machines.
 
Its poor service life behind a rotary is due to the shock wave = dropping=20 to subsonic by applying its energy to the flat sides of the design. It = is both=20 a rflective and an impinging design.
 
If saw cuts are made into the long axis of the fish tail shape = and bits=20 of metal are welded in place to prevent the flexing (and fatigue = death) of the=20 pieces, this design might be found quite effective.
 
Years ago I tried one of the big Suitcase Flowmaster mufflers on = the=20 racer. A reflective design and very effective. In one session of 45 = minutes,=20 all of the baffles were hammered loose and piled up at the exit pipe = and the=20 sides of the muffler swelled up like a giant pillow. The reflective = design was=20 changed to an impinging design. I was far from home at Sebring Florida = so I=20 cut open the Flowmaster and flatened the sides. I welded the baffles = back in=20 place with more than a spot weld here and there. I drilled through = both sides=20 behind each baffle and installed solid 1/4" rods to keep the flat = sides from=20 spreading open again.
 
I moved it to the very rear of the body where the heat load would = be=20 reduced.
 
That muffler lasted the rest of the season. It was sinfully heavy = and=20 really too big for anything but a big GM car, but it worked great on = the=20 rotary.
 
The Spintech or similar I think will fill the bill. More likely a = combination of two styles, or one style behind another. Any system = that does=20 not include equal length headers leave a bunch of HP on the table. =
 
Lynn E. Hanover
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