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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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