Bill,
I tried a Swiss muffler many
moons ago. I work great… for about 10 mins. The packing quickly disintegrated
and spit out the tail pipe. I tried every type of packing material I could
think of. Ceramic, Glass fibre, Carbon fibre Stainless steel wool, and mixes.
I tried replacing the wire mesh inner tube with SS tubing drilled full of
holes. I tried donut shaped baffle plates trying to hold the packing in place.
Nothing worked for more than ½ hour. Between the heat and the strong exhaust
pulse the rotary makes, none of the packing material had the mechanical
properties to hold up. The best material I found for packing was carbon fibre,
but again, it didn’t last long enough but for a circuit or two.
On the plus side, the sound this
muffler makes was music to the ear (for the first 15 mins at least).
Neil K
PS: I had a look through the archives but
they don’t go back far enough for my original posts.
From: Rotary motors in
aircraft [mailto:flyrotary@lancaironline.net] On
Behalf Of Bill Bradburry
Sent: Sunday, July 12, 2009 1:05
AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re:
Flowmaster Hushpower Report
From: Rotary motors in aircraft
[mailto:flyrotary@lancaironline.net] On
Behalf Of Mark Steitle
Sent: Saturday, July 11, 2009
11:47 PM
To: Rotary
motors in aircraft
Subject: [FlyRotary] Re:
Flowmaster Hushpower Report
For my first muffler attempt, I copied the spiral flow design for
my 20B. While it worked (passed gas), I wouldn't call it quiet, and
neither did my airport neighbors.
On Sat, Jul 11, 2009 at 9:42 PM, Mike Wills <rv-4mike@cox.net> wrote:
My "muffler" is a copy of this design. Except its made
of Inconel. Unfortunately it doesnt really serve its intended purpose of
muffling as you know. Could be my implementation as the center tube diameter
could be too large. I expect it will still be holding up just fine when I
replace it because it doesnt muffle. I'm thinking of trying the DNA muffler
next pending Mark's final results.
One more data point. My buddy has a Cobra kit car with Ford
302 V8. His side pipes also use the spiral flow design. The external pipe is
4" diameter, the internal is less than 1". So presumably a large
percentage of the flow goes through the spiral. But his car is still pretty
loud.
----- Original Message -----
Sent: Thursday, July 09,
2009 7:38 PM
Subject: [FlyRotary]
Flowmaster Hushpower Report
For the last couple hundred hours I have been using a Flowmaster
Hushpower II muffler. Also used by Tracy and some others I think.
It is done. The outside held up wery well, but I reciently removed it and
discovered that the insides have entirely disientigrated. Whatever they used
as packing has turned to a heavy clay-like substance ratteling around in
the bottom. She steel mesh is in pieces. I had been thinking
that the plane was not as quiet as it seemed 2 years ago.. go figure.
So I was thinking about one of the DNA Mufflers someone
mentioned. They seemed nice because there is no packing, just steel
dividers. Unfortunately, it is a little to big around to fit in my
current set up. Instead, I ordered this muffler that also has
steel innards but no packing:
It is nice because it is going to be smaller and lighter than the
flowmaster (or the DNA), as well as less expensive - even the SS version that I
ordered.
Will report back in 2 years on its performance :-)
--
David Leonard
Turbo Rotary RV-6 N4VY
http://N4VY.RotaryRoster.net
http://RotaryRoster.net