X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from qw-out-2122.google.com ([74.125.92.27] verified) by logan.com (CommuniGate Pro SMTP 5.2.16) with ESMTP id 3842085 for flyrotary@lancaironline.net; Tue, 08 Sep 2009 22:49:02 -0400 Received-SPF: pass receiver=logan.com; client-ip=74.125.92.27; envelope-from=rwstracy@gmail.com Received: by qw-out-2122.google.com with SMTP id 3so1102899qwe.25 for ; Tue, 08 Sep 2009 19:48:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:sender:received:in-reply-to :references:date:x-google-sender-auth:message-id:subject:from:to :content-type; bh=QV5p8tyIg2V68Dy4mgrOXAZS7IYO/kIlJZ7dthUuZUI=; b=YA/sY3u0SEEv9Gq+fEbMnS+fqy8JtgVlFmKnEaxJjdwZCJ2APQumdw+3MMk1nEJz9p m82x9o6VejIV7ll3/BmqnVYPWHIXcJ8mGH90C3c/jG8d+CowRODQpYZL6ALH+BOJ6/cE xm7O8ajU9Lo2r78Qntg2fki95nbaY58koJ4ho= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:content-type; b=KHvFgXURqfF6pG3XoYM6nWdMOjMmDGWCvmLW0snTyRF4WpP/0C05pUbwOXAmaHsKoT 7bOPL5mHK1lzQFvC/LlQGETlOXXU3ftvAwJeisHIM63YmcrZV52IIvJJbMIQv6BvxgCD LHJCf82jYV7e54w1EIpRSGOWD/C3QJJ6BAfqc= MIME-Version: 1.0 Sender: rwstracy@gmail.com Received: by 10.224.61.143 with SMTP id t15mr10629240qah.225.1252464508431; Tue, 08 Sep 2009 19:48:28 -0700 (PDT) In-Reply-To: References: Date: Tue, 8 Sep 2009 22:48:28 -0400 X-Google-Sender-Auth: 9c95109b5afa4e6d Message-ID: <1b4b137c0909081948x21fea992sc593377c2f270a13@mail.gmail.com> Subject: Re: [FlyRotary] Re: Muffling From: Tracy Crook To: Rotary motors in aircraft Content-Type: multipart/alternative; boundary=0014851f1ef61e6ea604731c1e6e --0014851f1ef61e6ea604731c1e6e Content-Type: text/plain; charset=ISO-8859-1 The Spintech was flown for about 200 hours with no problem. Guts stayed intact and it was slightly more effective than the Hushpower II was when new (before the packing departs). But it was heavy (can't remember the number) and the boxy profile cost me about 4 mph in cruise. If the Hushpower gets fried on the -8 (likely) I will give the Spintech a try again. BTW, I'm going to try a 1.75" reducer on my -4 (and maybe the -8 too). The test results we did on the test stand with a *1" reducer* were amazing. VERY quiet and the engine only dropped 200 rpm at static WOT. BTW, the 20B with turbo 13B rotor housings running through the Hushpower II is not as loud as the Renesis with the same (but probably internally damaged) muffler. I haven't had the guts blow out yet on the -8 but it is likely to happen when I get into the high power settings. Tracy On Tue, Sep 8, 2009 at 10:01 PM, Mike Wills wrote: > 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 > > ----- Original Message ----- > *From:* Lynn Hanover > *To:* Rotary motors in aircraft > *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. > > 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. > > 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. > > Lynn E. Hanover > > --0014851f1ef61e6ea604731c1e6e Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable The Spintech was flown for about 200 hours with no problem.=A0 Guts stayed = intact and it was slightly more effective than the Hushpower II was when ne= w (before the packing departs).=A0 But it was heavy (can't remember the= number) and the boxy profile cost me about 4 mph in cruise.=A0 If the Hush= power gets fried on the -8 (likely) I will give the Spintech a try again. <= br> BTW, I'm going to try a 1.75" reducer on my -4 (and maybe the -8 t= oo).=A0 The test results we did on the test stand with a 1" reducer= were amazing.=A0 VERY quiet and the engine only dropped 200 rpm at sta= tic WOT.

BTW, the 20B with turbo 13B rotor housings running through the Hushpowe= r II is not as loud as the Renesis with the same (but probably internally d= amaged) muffler.=A0 I haven't had the guts blow out yet on the -8 but i= t is likely to happen when I get into the high power settings.

Tracy

On Tue, Sep 8, 2009 at 10:01 PM= , Mike Wills <rv-4= mike@cox.net> wrote:
For Tracy,
=A0
=A0Can you refresh my memory on what h= appened=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.
=A0
=A0At this point I think I'd be wi= lling 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.
=A0
=A0Spintech wants $375 for a custom mu= ffler made=20 from 321 SS. The same muffler in aluminized mild steel is $116. I'm tem= pted to=20 buy the cheapie and try it out before committing the $375.
=A0
Mike Wills
RV-4 N144MW=A0
----- 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 a= nd=20 other machines.
=A0
Its poor service life behind a rotary is due to the shock wave dropp= ing=20 to subsonic by applying its energy to the flat sides of the design. It is= both=20 a rflective and an impinging design.
=A0
If saw cuts are made into the long axis of the fish tail shape and b= its=20 of metal are welded in place to prevent the flexing (and fatigue death) o= f the=20 pieces, this design might be found quite effective.
=A0
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 minut= es,=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 desig= n 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 s= ides=20 behind each baffle and installed solid 1/4" rods to keep the flat si= des from=20 spreading open again.
=A0
I moved it to the very rear of the body where the heat load would be= =20 reduced.
=A0
That muffler lasted the rest of the season. It was sinfully heavy an= d=20 really too big for anything but a big GM car, but it worked great on the= =20 rotary.
=A0
The Spintech or similar I think will fill the bill. More likely a=20 combination of two styles, or one style behind another. Any system that d= oes=20 not include equal length headers leave a bunch of HP on the table.
=A0
Lynn E. Hanover

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