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Date: Wed, 20 Apr 2011 08:00:26 -0700
Message-ID: <BANLkTi=yPMr7bNKcBKgpcu60L_XDqvoBxA@mail.gmail.com>
Subject: Re: [FlyRotary] Re: Burns Stainless Muffler Failure
From: William Archer <archerwt@gmail.com>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Content-Type: multipart/alternative; boundary=20cf303a31b1930d5d04a15ae285

--20cf303a31b1930d5d04a15ae285
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One thing I wish I had done but never got around to it was to section some
rusty stock mufflers on their way to the recycler.  I don't recall anyone
having done this in order to replicate Mazda's shapes and routing.  A
cursory look at the rx7 auto sites don't provide much.

Todd



> 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
>



> I just did an inspection of my muffler and found that it was basically
>> coming apart inside.  This is a Burns Stainless, 17" 2-Stage muffler after
>> 50 hours of flying behind a 2-rotor engine.  Now, it could be that 50 hours
>> is a reasonable life for something like this, I don't know.  But, it
>> certainly confirms the stories of muffler disintegration.  I've inspected
>> this muffler several times over the last 50 hours, but this is the first
>> time that I've seen damage.  But, when it comes apart, it really comes
>> apart.  It is unfortunate, as the muffler was really effective in reducing
>> the noise and was light-weight.
>>
>>
>> Best Regards,
>>
>> Steve Thomas
>>
>>

--20cf303a31b1930d5d04a15ae285
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<div>One thing I wish I had done but never got around to it was to section =
some rusty stock mufflers on their way to the recycler.=A0 I don&#39;t reca=
ll anyone having done this in order to replicate Mazda&#39;s shapes and rou=
ting.=A0 A cursory look at the rx7 auto sites don&#39;t provide much.</div>

<div>=A0</div>
<div>Todd<br></div>
<div class=3D"gmail_quote">
<div>=A0</div>
<div>=A0</div>
<blockquote class=3D"gmail_quote" style=3D"PADDING-LEFT: 1ex; MARGIN: 0px 0=
px 0px 0.8ex; BORDER-LEFT: #ccc 1px solid">Hi Thomas,<br><br>Thanks for the=
 photo.<br><br>The exhaust pulse from the rotary is just incredible powerfu=
l. =A0Any flat surface perpendicular to the pulse (such as the end of you m=
uffler), appears to be doomed to fatigue failure from the pounding of the p=
ulse.<br>
<br>I once squished the tips of 2&quot; dia SS steel tubes together and dri=
lled holes to make a &quot;fishtail&quot; sound suppressor. =A0After a 30 m=
in flight, I came back to find chunks of the SS tube missing where the puls=
e had hammer and fatigued the tips during that short flight.<br>
<br>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.<br><b=
r>Better luck on your next choice<br><br>Ed<br>=A0</blockquote>
<div>=A0</div>
<blockquote class=3D"gmail_quote" style=3D"PADDING-LEFT: 1ex; MARGIN: 0px 0=
px 0px 0.8ex; BORDER-LEFT: #ccc 1px solid">
<blockquote class=3D"gmail_quote" style=3D"PADDING-LEFT: 1ex; MARGIN: 0px 0=
px 0px 0.8ex; BORDER-LEFT: #ccc 1px solid">I just did an inspection of my m=
uffler and found that it was basically coming apart inside. =A0This is a Bu=
rns Stainless, 17&quot; 2-Stage muffler after 50 hours of flying behind a 2=
-rotor engine. =A0Now, it could be that 50 hours is a reasonable life for s=
omething like this, I don&#39;t know. =A0But, it certainly confirms the sto=
ries of muffler disintegration. =A0I&#39;ve inspected this muffler several =
times over the last 50 hours, but this is the first time that I&#39;ve seen=
 damage. =A0But, when it comes apart, it really comes apart. =A0It is unfor=
tunate, as the muffler was really effective in reducing the noise and was l=
ight-weight.<br>
<br><br>Best Regards,<br><br>Steve Thomas<br><br></blockquote></blockquote>=
</div>

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