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| I used a ball joint and bend to transition the pipe rearward just inside the cowl. That along with flexible exhaust hangers did a good job of decoupling vibration.
Bobby Sent from my iPad On Oct 6, 2020, at 8:29 PM, Matt Boiteau mattboiteau@gmail.com <flyrotary@lancaironline.net> wrote:
It's 42miles as the crow flies. I got the normal 25nm increased to 45nm. Now that I'm flying, I'll update the group on my progress. 8 hours in. I think the exhaust is shaking the plane, I was hoping the engine be a smoother plane ride. What do people torque down the Berry mounts to, really tight to compress?
Hey, I'm just a stone-throw away
(9FL5). Surely your test area is includes that?
You're welcome to stop by.
Finn
On 9/30/2020 8:59 AM, Matt Boiteau mattboiteau@gmail.com wrote:
Williston (X60 airport)
I'll be there from Oct 3rd to 29th, to fly off my 25hours. So
far I have 6 hours and had to increase my oil inlet duct size,
and redo the exhaust so I could hear. We'll see what new bugs
will pop up. I'll be posting a lot to keep people in the loop
and help me along the way.
If people want to visit in person to check out the setup and
give me advice, I'm all ears.
Where
in Florida? I live in Florida in the winter. Lynn E.
Hanover
In a message dated 9/30/2020 12:48:34 AM Atlantic Standard
Time, flyrotary@lancaironline.net
writes:
I've been stuck in Canada far too long.
Finally flying to Florida on Sat to see my plane and
start flying off the hours (trouble free I hope)
my email is my name (without spaces) at normal gmail
dot com.
Matt,
Did
you make it back to Canada in time for the
first snow? I would like to discuss your
MS install off list when you have time.
Bobby
From: Rotary motors in
aircraft [mailto:flyrotary@lancaironline.net]
Sent: Wednesday, July 08,
2020 7:10 PM
To: Rotary motors in
aircraft
Subject: [FlyRotary] Re:
Mufflers
Sadly, by the time the welder and I
finished, I only got about 2 hours on the
plane before I had to pack up my winter
trip. I was planning to go back in March
to FL (I live in Canada) to start flying
off the 25 hours, but you know how that
all went. So I'm just sitting here waiting
for the borders to open up and fly my
plane!
Early conclusion is it worked pretty darn
good. I'd say I'm equivalent to an IO-360,
maybe a tad quieter. Also on ground
testing only, I quickly mocked up a long
tube under the plane with holes drilled in
it (with the end capped off), and it
pretty much got rid of all the engine
noise, only prop noise. Haven't flown with
that yet. One thing I still want to do is
test the backpressure. Making sure the CAN
has enough holes inside.
The best price I found on 321 was from
ProFabrication. I went with 2.75" 20ga
(0.035") on the downpipe & outlet.
https://www.profabrication.com/index.php/products/straight-tubing/321-stainless-steel.html
I did use SPD Exhaust for the double slip
joints at the primaries and downpipe. 2"
16ga (0.06")
http://www.spdexhaust.com/pdfs/22-23_Tubing.pdf
For the CAN, McMasterCarr 24"x24" 18ga
(0.05") rolled into I think a 5 or 5.5"
can. You can go heavier ga, I just
guessed.
https://www.mcmaster.com/1754T51/
I’m
at the exhaust header stage in my
S21 FWF build. I’m considering a
traditional header, 3-1 merge
collector with 1.75” primaries to
a 2.5” tube. I’m trying to be very
weight conscious and looking for
possible alternatives. The CA
manifold can likely be built for
nearly the same weight as the
header design in the picture. I’m
a little concerned with the
tangential design. Mark S built
and tested one on his 20B. It ran
hot and caused the outer water
jacket seals to fail. Mark was not
running a wideband so he couldn’t
see a clear relationship between
F/A and EGT’s. He may have be
running at or near peak EGT’s.
EGT’s for the renesis can be kept
to between 1500F -1600F with a
little extra or a little less
fuel. I will like install the
coolant radiator on the belly so
adding an external muffler would
keep it off centerline.
I
have located some reasonable
priced Inconel 625 0.040 sheets.
If rolled into a 5-6” tube, would
this thickness be sufficient for a
muffler shell or the CA /
tangential manifold tube?
Matt,
How
is your CA header holding up?
Thanks,
Bobby
From: Rotary motors in
aircraft [mailto:flyrotary@lancaironline.net]
Sent:
Saturday, January 25, 2020
7:53 PM
To: Rotary
motors in aircraft
Subject:
[FlyRotary] Re: Mufflers
Okay
so after 2 full days of having
our welder out, finally brought
the CAD design to life. Except
both days were all nighters, so
I was too tired and busy to take
'in progerss' pictures. Was
tricky to build, which made the
hourly welding cost sky high,
more then the engine itself.
Hopefully that means I can save
money in the future on hearing
aids.
Thanks Charlie for the tip on
the spectrum analyzer. I didn't
get any before numbers, but it's
all low Hz now. That harsh high
pitch is gone. Db's are still
there, but I'd say with just the
muffler design, it's comparable
to typical lycoming. I can start
to hear the prop noise over the
engine noise. I measured back
pressure around 3.5psi @ 2200rpm
prop.
I ran out of time to flight test
the long pipe under the
airplane. I quickly held it up
with my hands and the exhaust
pretty much disappeared with the
prop taking over the noise.
Before flying, I want to add
backpressure gauge to that part
and drill holes to find a
balance between backpressure and
noise.
SO
the "header" muffler should
make quite like any other
plane, and the "under belly"
pipe will make you standout
in silence.
On
2020-01-18 5:29:51 PM, Matt
Boiteau <mattboiteau@gmail.com>
wrote:
Have
started on the exhaust.
Made all three primaries
2" double slip joints
(that alone took almost a
whole day with welder).
The big can (CA
- Centrifugal Accumulator)
rolled into a 5" can and
we'll secure it to the
engine with straps.
The inside pipe is 2.75"
which has an area of
5.94sq". I'm not sure if
there's a magic number,
but all the holes I
drilled equaled to just
under double the area
(11sq"). Most are 3/8, but
I did add some 1/2 to get
the total area up. Could
we get away with drilling
less holes? Not sure. I'll
be able to drill out one
side end of the CA and
pull out the inner tube
and change out.
Will experiment later with
less holes and monitor
back pressure. Will weld a
npt bung on the CA and use
the wideband bung to
measure the different.
The previous exhaust with
just an Aero Turbine
2525XL, measured ~113dBA.
With nothing, was closer
to 120dBA. Funny around
2000 prop rpm was louder
then at 2300 full static.
Error! Filename
not specified.
On
2020-01-07 12:19:23 AM,
Matt Boiteau mattboiteau@gmail.com
<flyrotary@lancaironline.net>
wrote:
Okay
I'll make all 3
primary tubes (2"
diameter) all
double slip fit.
Welding batwing tabs
(picture below) on
to either side on
the slips, will
hold the muffler
to the header but
allow expansion.
Having
troubles finding
2.75" bends in
321, so I might
have to just
switch to 3"
downpipe that is
more common. Vband
clamp before
downpipe for
easier removal and
under the plane to
allow adding
additional exhaust
setups (long pipe
with holes drilled
in it, fishmouth
tailpipe, etc)
Error!
Filename not
specified.
Error!
Filename not
specified.
On
2020-01-03 4:22:18
PM, Neil Unger 12348ung@gmail.com <flyrotary@lancaironline.net> wrote:
Mat,
As usual I have
no idea. I made
all 3 slip
joints and to
date no grief in
that area. I am
coming around to
the stock
manifold in some
way. Yes it is
heavy, but
appears to
muffle the noise
as well. Know
of 2
installations
that use the
stock manifold
with a simple
muffler after
and both claim
"acceptable"
noise. It
appears that the
stock manifold
has a big
influence on
noise?? Would
prefer a DB
reading, but if
not available it
is what it is.
All is
compromise,
weight, cost,
time, but at the
end of the day
it has to work.
Still
working on the
turbo even
though the world
is on holidays.
All to save my
hearing. So far
the rotary is
definitely
"unique" as far
as a turbo is
concerned. The
heat generated
exceeds all
else Two things
to date --
special exhaust
wheel and water
cooled bearing
body =, all for
heat. Have
modified the
stock front
plate on the
renesis to take
an electric
water pump.
That is the
simple bit.
Neil.
okay
I found a good
company called
SPD Exhaust.
They have
everything you
need in 321ss.
With the
engine being
an RX8, we
have three
exhaust ports.
Should I weld
the front and
back solid to
the muffler,
and make the
middle one a
slip fit for
expansion? Or
vice-vesa?
Error!
Filename not
specified.
On
2019-12-28
11:03:42 AM,
Finn Lassen finn.lassen@verizon.net <flyrotary@lancaironline.net> wrote:
I
did something
similar with
my RV-3 13B
decades ago.
It split open
at the welds
around one of
the pipes from
the manifold
into the the
big outer tube
True, it did
use individual
manifold base
plates, not
the connected
factory
manifold and
the big tube
was only
0.035.
Still, I would
recommend slip
joints on two
of the three
pipes, like I
added on one
of the pipes
(cut through
and a
surrounding
bigger pipe --
missing in
picture).
Error!
Filename not
specified.
Can't remember
why I went
from the above
to individual
runners into a
perforated
pipe under the
fuselage.
Probably got
lured by
promise of
increased
power by tuned
lengths and
still
uncomfortable
by the muffler
being inside
the cowling.
Finn
On 12/28/2019
12:10 AM, Matt
Boiteau mattboiteau@gmail.com wrote:
This
is what I'm
going to try
in a few
weeks.
"Exhaust
valve opens
and a pulse of
hot gas puffs
out through a
short pipe,
then tangentially into
a cylindrical
canister.
Being
tangential,
the pulse
flattens out
and travels helically (rather than
bouncing and
reverberating
around) along
the inside
curved wall of
the can,
spiraling
toward the
exit, where it
comes out more
uniform in
flow and so
pretty quiet."
Outer
pipe = 321 ss
0.050 thick.
Flat plate
bent to a 5"
tube
Inner
pipe = 321 ss
0.036 thick.
2.5" diameter
(I
might use
302ss 0.065
since I
already have
it)
>From
my
understanding,
the area of
the holes
should be
double the
area of the
inner pipe.
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