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Prop balancing was my first thought
too.
Engine will not vibrate unless you've got faulty ignition, intake
problems or similar.
I'm my RV-4 I won't have to torque down Berry mounts. I don't have
any. Tracy talked me out of using them.
That, of course, makes prop balancing essential. I'm currently
fitting the spinner to the RV-4 -- perhaps a few more days.
There's a place where one can rent a dynamic prop balancer for a
week for $150. Perhaps we could share the cost?
Finn
On 10/6/2020 9:29 PM, Matt Boiteau mattboiteau@gmail.com 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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