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From: "William" <wschertz@ispwest.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
References: <list-923151@logan.com>
Subject: Re: [FlyRotary] Cool Tube Muffler Sound Readings
Date: Wed, 11 Jan 2006 20:49:48 -0600
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Glad to hear that the muffler seems to be working. Please check often for 
stress/fatigue cracks at the joint of the short tubes to the big round can. 
The can expands and contracts with each heating cycle, and the other end of 
the tubes are fixed by the temperature of the block. It may be okay, but 
worth checking frequently until you get experience.
Bill Schertz
KIS Cruiser # 4045
----- Original Message ----- 
From: "Bob White" <rlwhite@comcast.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Wednesday, January 11, 2006 6:00 PM
Subject: [FlyRotary] Cool Tube Muffler Sound Readings


> Today I ran the engine to get the sound level readings.
>
> Short review:
> This is the cool tube muffler built by Jerry Hey.  Each exhaust port
> has a short tube into a large round can.  The center of the can has a
> two inch tube down the center to permit cool air to aid in cooling the
> exhaust.  This tube is sealed from the actual exhaust gasses.  The
> exhaust exits the large tube thru a rectangular tube at the bottom of
> the large round can.  (photo attached)
>
> Here are the sound level readings with the engine running at 3000 RPM
>
> Location A C
> -------------- --- ---
> Left Wing 98 105
> Right Wing 96 105
> Front (5 paces) 95 105
> Tail 91 103
> Pilot Seat 84 94
>
> The A weighting cuts out the low frequencies below 500 Hz.  I have no
> idea how these compare to the typical aircraft engine.  According to
> the instruction manual, the A weighting is used to determine area noise
> levels, and C wighting is used to measure sound levels of musical
> instruments.
>
> I will get some higher rpm measurements after I get a little more time
> on the engine.
>
> Coolant temps seemed to stabilize at 200F and oil at 175F with the
> engine at 2500-3000 rpm tied down and no cowling installed.  I ran it
> for around 10 minutes in this mode.
>
> Bob W.
>
> -- 
> http://www.bob-white.com
> N93BD - Rotary Powered BD-4 (first engine start 1/7/06)
> Custom Cables for your rotary installation -
> http://www.roblinphoto.com/shop/
>


--------------------------------------------------------------------------------


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