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From: btilley@mchsi.com
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Muffling
Date: Wed, 09 Sep 2009 00:15:56 +0000
Message-Id: <090920090015.16865.4AA6F3BB000B9B63000041E1223045151403010CD2079C080C03BF970A0404079B0D@mchsi.com>
In-Reply-To: <list-3840940@logan.com>

Lynn,

Some speculation going on here.  When you run the exhaust thru a turbo, will it break up the pulses enough for a fishtail to work? I'm hoping to use a fishtail to create an augmentor out the back of my plane. Should I reinforce the fishtail to insure rigidity?

Bob Tilley
Albany, Ga
temporarly on loan to Baton Rouge

-------------- Original message ----------------------
From: Lynn Hanover <lehanover@gmail.com>
>
> 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