----- Original Message -----
Sent: Tuesday, March 08, 2005 10:08
PM
Subject: [FlyRotary] Re: Anechoic
Muffler
I remember an older brother saying that to a neighbor
girl.
Ok, here it is revealed to the world. Ed, you
introduced me to the DIE concept of the intake system, where essentially
pulses are reflected back toward the intake port. I later
read more about this when looking up plenums and they recommended having a
flat wall for these pulses to be reflected. My latest
iteration for an 'anechoic muffler' is the opposite. The exhaust
header/muffler is shaped like a V laying on it's side, as viewed from the end
of the motor. The exhaust from the ports is shot into it
between these walls and hopefully attenuated as it
narrows. At both ends of this thing you have end
plates. At one or both ends of this thing you have an exhaust port
for the gasses to flow out. The specific angle
of the v probably depends on wave characteristics and needs to be putzed with
to optimize. It's maybe best constructed from thicker
material to better deal with the pulses.
Due to interference from the motor mount you'de probably need runners and
place this outside the mount. In this case, you don't necessarily need
to orient the V on its side, you can make your feeding exhaust pipes turn 90
degrees downward into a properly oriented V and catch all the apex seal debris
for inspection. Hey, make it protrude downward from the
bottom-center of your cowl and let the outside airstream cool it.
Other variations, have smaller individual v-chambers per exhaust
port. With this you have more flexibility on their
placement. Then you may or may not wish to join the exhaust
gas outputs into a common exhaust pipe.
Thats the basic concept. Can you weld one of
these over the weekend and give it a spin?
Tom Tugan
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