Yes, Bill
My suggestion is don’t waste your
time. Perhaps with substitutes of material it might could be make to work
for a short time. However, I have not yet seen a muffler using any sort
of absorb material (including ceramic wool which I tried – withstood the
heat fine, but not the pulse) that can withstand the shock wave of the rotary
exhaust. Whether stainless steel, fiberglass, ceramic, etc, etc, can all
withstand the heat, within a few weeks the exhaust pulse has pulverized the
absorbent material and blown it out the exhaust. The ones that seem to
last the longest are the acoustic baffle type. YMMW
Ed
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
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