From: "Stephen Izett stephen.izett@gmail.com" <flyrotary@lancaironline.net>
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Subject: Re: [FlyRotary] Mufflers
Date: Wed, 7 Oct 2020 09:37:29 +0800
References: <list-812753@logan.com>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
In-Reply-To: <list-812753@logan.com>
Message-Id: <08870D1B-346F-414E-ABF3-C0D107F03659@gmail.com>

Hi Matt

Has your Prop been dynamically balanced?

Steve Izett

> On 7 Oct 2020, at 9:29 am, Matt Boiteau mattboiteau@gmail.com =
<flyrotary@lancaironline.net> wrote:
>=20
> It's 42miles as the crow flies. I got the normal 25nm increased to =
45nm.=20
> 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?
>=20
> - Matt Boiteau
>=20
>=20
> On Wed, Sep 30, 2020 at 2:02 PM Finn Lassen finn.lassen@verizon.net =
<flyrotary@lancaironline.net> wrote:
> Hey, I'm just a stone-throw away (9FL5). Surely your test area is =
includes that?
> You're welcome to stop by.
>=20
> Finn
>=20
> 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.
>>=20
>> If people want to visit in person to check out the setup and give me =
advice, I'm all ears.
>> =20
>> - Matt Boiteau
>>=20
>>=20
>> On Wed, Sep 30, 2020 at 5:38 AM lehanover lehanover@aol.com =
<flyrotary@lancaironline.net> wrote:
>> Where in Florida? I live in Florida in the winter.   Lynn E. Hanover
>> =20
>> In a message dated 9/30/2020 12:48:34 AM Atlantic Standard Time, =
flyrotary@lancaironline.net writes:
>> =20
>> 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.
>>=20
>> - Matt Boiteau
>>=20
>> On Tue, Sep 29, 2020 at 3:02 PM Bobby J. Hughes bhughes@qnsi.net =
<flyrotary@lancaironline.net> wrote:
>> Matt,
>>=20
>> =20
>> 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.
>>=20
>> =20
>> Bobby
>>=20
>> =20
>> =20
>> =20
>> From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]=20=

>> Sent: Wednesday, July 08, 2020 7:10 PM
>> To: Rotary motors in aircraft
>> Subject: [FlyRotary] Re: Mufflers
>>=20
>> =20
>> 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!
>>=20
>> 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.
>>=20
>> 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-stai=
nless-steel.html
>>=20
>> 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 =20
>>=20
>> 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.=20
>> https://www.mcmaster.com/1754T51/ =20
>>=20
>>=20
>> - Matt Boiteau
>>=20
>> =20
>> =20
>> On Wed, Jul 8, 2020 at 2:35 PM Bobby J. Hughes bhughes@qnsi.net =
<flyrotary@lancaironline.net> wrote:
>>=20
>> I=E2=80=99m at the exhaust header stage in my S21 FWF build. I=E2=80=99=
m considering a traditional header,  3-1 merge collector with 1.75=E2=80=9D=
 primaries to a 2.5=E2=80=9D tube. I=E2=80=99m 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=E2=80=99m 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=E2=80=99=
t see a clear relationship between F/A and EGT=E2=80=99s.  He may have =
be running at or near peak EGT=E2=80=99s. EGT=E2=80=99s 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.
>>=20
>> =20
>> I have located some reasonable priced Inconel 625 0.040 sheets. If =
rolled into a 5-6=E2=80=9D tube, would this thickness be sufficient for =
a muffler shell or the CA / tangential manifold tube?
>>=20
>> =20
>> Matt,
>>=20
>> =20
>> How is your CA header holding up?
>>=20
>> =20
>> Thanks,
>>=20
>> =20
>> Bobby
>>=20
>> =20
>> From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]=20=

>> Sent: Saturday, January 25, 2020 7:53 PM
>> To: Rotary motors in aircraft
>> Subject: [FlyRotary] Re: Mufflers
>>=20
>> =20
>> 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.
>>=20
>> 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.
>>=20
>> 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.
>>=20
>> =20
>> SO the "header" muffler should make quite like any other plane, and =
the "under belly" pipe will make you standout in silence.
>>=20
>> =20
>> Since this email type newsletter is from the dinosaur ages, I'll add =
pictures and video to =
https://www.homebuiltairplanes.com/forums/threads/exhaust-within-subcowl.3=
0848/page-2#post-512762
>>=20
>> =20
>> - Matt Boiteau
>>=20
>> On 2020-01-18 5:29:51 PM, Matt Boiteau <mattboiteau@gmail.com> wrote:
>>=20
>> 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.
>>=20
>> 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.
>>=20
>> 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.=20
>>=20
>> Error! Filename not specified.
>>=20
>> =20
>> - Matt Boiteau
>>=20
>> On 2020-01-07 12:19:23 AM, Matt Boiteau mattboiteau@gmail.com =
<flyrotary@lancaironline.net> wrote:
>>=20
>> 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.
>>=20
>> =20
>> 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)
>>=20
>>=20
>> I found a company that makes flex bellows in 321. I'm just not sure =
if I should have it vertical on the downpipe or close to the muffler =
horizontal before the first 90degree bend downwards.
>> =
https://www.aceraceparts.com/products/3-000-flex-bellow-assembly-321-stain=
less?variant=3D11067135556
>>=20
>> Error! Filename not specified.
>>=20
>> =20
>> =20
>> Batwing tabs
>>=20
>> Error! Filename not specified.
>>=20
>> =20
>> - Matt Boiteau
>>=20
>> On 2020-01-03 4:22:18 PM, Neil Unger 12348ung@gmail.com =
<flyrotary@lancaironline.net> wrote:
>>=20
>> Mat,
>>=20
>>                   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.=20
>>=20
>> 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 =3D, all =
for heat.  Have modified the stock front plate on the renesis to take    =
                                                     an electric water =
pump.  That is the simple bit.
>>=20
>> Neil.
>>=20
>> On 1/4/2020 5:37 AM, Matt Boiteau mattboiteau@gmail.com wrote:
>>=20
>> okay I found a good company called SPD Exhaust. They have everything =
you need in 321ss.
>>=20
>> 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?
>>=20
>> Error! Filename not specified.
>>=20
>> =20
>> - Matt Boiteau
>>=20
>> On 2019-12-28 11:03:42 AM, Finn Lassen finn.lassen@verizon.net =
<flyrotary@lancaironline.net> wrote:
>>=20
>> 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.
>>=20
>> 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).
>>=20
>> Error! Filename not specified.
>>=20
>> 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.
>>=20
>> Finn
>>=20
>> On 12/28/2019 12:10 AM, Matt Boiteau mattboiteau@gmail.com wrote:
>>=20
>> This is what I'm going to try in a few weeks.=20
>>=20
>> "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."
>>=20
>> =20
>> Outer pipe =3D 321 ss 0.050 thick. Flat plate bent to a 5" tube
>>=20
>> Inner pipe =3D 321 ss 0.036 thick. 2.5" diameter
>>=20
>> (I might use 302ss 0.065 since I already have it)
>>=20
>> =20
>> >=46rom my understanding, the area of the holes should be double the =
area of the inner pipe.=20
>>=20
>> =20
>> - Matt Boiteau
>>=20
>> =20
>> =20
>> Disclaimer
>>=20
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