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George,
I agree and that's why my muffler isnt in the
cowl. But I also agree with Tracy - unless/until somebody finds the magic
muffler, the best solution to this problem is muffler volume. A large muffler
isnt going to work on my airplane. Perhaps a different airplane with more space
within the cowl would accomodate a muffler and some heat shielding, but
that option doesnt apply for me. So I wish you luck with your design - I could
use it.
Mike
----- Original Message -----
Sent: Tuesday, January 06, 2009 12:50
PM
Subject: [FlyRotary] Re: 20B install
issues overcome
Mike,
Mufflers were never designed to fit into engine
bays because of the size and heat, that's why I have decided to have mine
outside the cowl. The fact that it is designed for cooling air both internally
and externally, and is designed aerodynamically for that, I believe that's the
best place for it. It may be that I can incorporate it into a cowl design so
that it's not too draggy - will just have to wait and see.
BTW Bill Jepson had a big input into this design,
but I have been a long time in proving the design.
George (down under)
----- Original Message -----
Sent: Tuesday, January 06, 2009 12:54
PM
Subject: [FlyRotary] Re: 20B install
issues overcome
I thought about it, but that hardware doesnt
fit well in the RV-4 cowl either.
Mike
----- Original Message -----
Sent: Monday, January 05, 2009 5:35
AM
Subject: [FlyRotary] Re: 20B install
issues overcome
Mike,
Actually, reducing exhaust noise is one of the beneifts of
turbo-charging.
Mark S.
On Sun, Jan 4, 2009 at 8:35 PM, Mike Wills <rv-4mike@cox.net> wrote:
Well when the E-Racer that was built by
George Graham was on the airport it was about the only prop plane louder
than mine. That airplane was ear splitting loud. So I'm not sold on the
prop as a noise reducer. Give yourself more credit Al, you've actually
engineered and built a muffler that works.
Mike Wills
----- Original Message -----
Sent: Sunday, January 04, 2009
8:45 AM
Subject: [FlyRotary] Re: 20B
install issues overcome
I guess the prop chopping the noise stream could
account for some of the perception of quietness. As for the
muffler/resonator, 6db is a significant reduction. I think I
still have the drawings you provided. The nice thing about the
tangential muffler design is that it will fit inside my cowl.
The muffler/resonator should fit where the Hushpower 2 is now.
We'll see. Mark
On Sun, Jan 4, 2009 at 10:17 AM, Al Gietzen
<ALVentures@cox.net> wrote:
Subject: [FlyRotary] Re: 20B
install issues overcome
My
exhaust exits about 6-7 inches from prop and goes through near the
root of the blades (pusher). It occurs to me that having my exhaust
exit through the prop may help reduce or mask the exhaust noise.
On a takeoff roll there is a prop blade breaking that exhaust
stream about 130 times per second. Let's see, that's about 1 blade
passing for every two exhaust pulses on the 20B – could make a
difference.
The
secondary muffler/resonator I have also helps. On the dyno we
measured that resulted in about 6 db reduction.
Al
G
Agree. Unfortunately, that's not a
comment I hear. On the contrary, they usually tell me that
they can hear me before they can see me. ;-(
Mark S.
ANR headsets mandatory
On Sun, Jan 4,
2009 at 12:22 AM, Al Gietzen <ALVentures@cox.net> wrote:
I'm
presently gathering materials to fabricate a tangential muffler made
from inconel, similar to your design. I take it from your
report that your muffler is holding up well?
Mark S.
So far it
is doing fine. And the inconel tangential and the 321SS
secondary muffler (my own design) quiet it down nicely. A few
days ago I picked up my brother to go for a ride, while my
sister-in-law waited and watched other planes come and go.
When we got back her remark was that my plane was quieter than all
the rest. I consider that to be 'expert
testimony'J.
Al
G
On Sat, Jan 3,
2009 at 5:47 PM, Al Gietzen <ALVentures@cox.net> wrote:
Al,
That's a great shot. Have you had any "significant
issues" with your install? If so, how did you overcome
them?
Mark S.
I had 2
issues that required some time and determination. The first was the
RWS EC2. I had an early version for the 3-rotor, and perhaps
the first installed in a composite airplane. I had some kind
of electrical noise related corruption of settings which persisted
through a lot of effort for over a years time. It has been resolved,
and the engine running fine. That has been discussed here more
than once in the past.
The other
was less-than-expected performance of an oil cooler built into the
wing root, without much of a scoop for the inlet below the wing.
The theory was that the differential pressure below/above the
wing would help provide the necessary air flow. Not the case
here as the location is too far back on the wing; and behind the
strake (the inboard section on the canard airplane). The
pressure differential turned out to be only about 1" H20 – very
little help. I added a ram scoop, and installed a small
oil/water heat exchanger in the cowl. Currently oil temps are
fine, and the coolant temp is running a bit lower than I like at
cruise. I may eventually install some sort of air flow
adjustment, or even consider installing a thermostat in the engine.
You may recall discussion of these changes here in the past as
well.
I'm just
past 140 hours flying time, and feel quite fortunate with how well
things have worked out. Performance and economy are
great.
Al
G http://members.cox.net/alg3/airplane.htm
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