X-CGP-ClamAV-Result: CLEAN X-VirusScanner: Niversoft's CGPClamav Helper v1.23.0 (ClamAV engine v0.103.0) X-Junk-Score: 0 [] X-Cloudmark-Score: 0 [] X-Cloudmark-Analysis: v=2.3 cv=eMxtc0h1 c=1 sm=1 tr=0 a=ApVsoW9ZcMvBPLtsjcKfQA==:117 a=reM5J-MqmosA:10 a=ZPv60q_EFhsA:10 a=r77TgQKjGQsHNAKrUKIA:9 a=pGLkceISAAAA:8 a=3oc9M9_CAAAA:8 a=Ia-xEzejAAAA:8 a=UKPAHat8AAAA:8 a=K9YiWmrbAAAA:8 a=W-IJHtK-AAAA:8 a=5lucXWJGAAAA:8 a=xPyZ54XvAAAA:8 a=jV3BzgDzAAAA:8 a=o1OHuDzbAAAA:8 a=jThZ7_-JAAAA:8 a=7g1VtSJxAAAA:8 a=_6GpL_ENAAAA:8 a=ayWJ1UkZeb7y_HYWv7QA:9 a=gzeXO55khHWg8Hom:21 a=08VbwKE1QT9zh1-z:21 a=QEXdDO2ut3YA:10 a=KGhxpC5zL1cA:10 a=Qa1je4BO31QA:10 a=lbVkQV85mo0A:10 a=F6a2BMeBdsAA:10 a=gvSQh4r-fQ0A:10 a=S0wkRrzPavQA:10 a=4PR2P7QzAAAA:8 a=sC2-BTICADQhwwk46kMA:9 a=1ZcuBsoKaptEPE8A:21 a=THSL52kyhHin7j-f:21 a=UeHc_xB5HueVvIJ2:21 a=_W_S_7VecoQA:10 a=Urk15JJjZg1Xo0ryW_k8:22 a=Fc6xXSS-RxGHxrvp76Qp:22 a=4fN42X7Z35HiWFx1RDDL:22 a=PjCiafSWRo16AjQHjZXP:22 a=tjNemD4wtFR24VrVMQME:22 a=LQCduUwlY3eUW_MavTj7:22 a=9Uz93n4haClHrRxSevy5:22 a=5YQ6H4ZxyGn-KoBYtt8s:22 a=NVbvhy2gKIdozzgvQOKv:22 a=grOzbf7U_OpcSX4AJOnl:22 a=4dqwQCo7Po2mVW515mGf:22 From: "Finn Lassen finn.lassen@verizon.net" Received: from sonic308-9.consmr.mail.ne1.yahoo.com ([66.163.187.32] verified) by logan.com (CommuniGate Pro SMTP 6.2.14) with ESMTPS id 799040 for flyrotary@lancaironline.net; Wed, 30 Sep 2020 14:02:00 -0400 Received-SPF: pass receiver=logan.com; client-ip=66.163.187.32; envelope-from=finn.lassen@verizon.net DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=verizon.net; s=a2048; t=1601488903; bh=yLLn2gN9Ih4MpJTXooxVLuNQ86BhSfP/pYK45QM9S8c=; h=Subject:To:References:From:Date:In-Reply-To:From:Subject; b=eBVS9eTiMrnpkhfb4cOxLH7+XhIZ+Gu9F8hk010DRgh8dhzh0VZBh7tHkNvqZXAT00B0Eovv4A4vf2pHwvTRVAJFLvMLxhHZSq3scCZ8DZxBT6+P3U568q9wWr+bnh/ugzlBA+Rj7BcVdAQkfrWE7rhioDEHgrMQkd8cxPXoDgAwHbM4VWFFHVp7G+21SOe9bKAjxwud0s5lUwlg2lWeAXKbiTVMbfl0MRRYvB42efiwuh34y2c2EU2KNNynPuwLJPG3HxxpB0CgBCtZ2ZPb3BBXXv5Nm2/YxF92AKoVsBoP3wEC0mxunwZEQ18/5L5KJd1+ibpyHqgvrGQn/evx1g== X-YMail-OSG: JRb.1yAVM1lwJH713vZvVoRtBycGeup.LErOxWUZ98rlEjysSugZwaeKN7qH7_8 sd1O9sgGNGxC1Dzeg3c4fMANYAfS.iOMMqseEt7fROaydBtFT9fbU_ZHy2aVT2gde64czKo1kf2d AzwOFzPYM6cPnPtrKCFyACuyKcDAh0fa.DMdjgmOwhm.1KCnAYVO27Pe3JT2QqDDYU95T_G5fhbN XMg8F_zOUqwbjAKfykhIJD6VskxidSzmCKTN7FQ2BlD5rwZT2zWoFIKn.b9CbCnD2wRBvEz_KX7y DzEtDsU625KKpVb2UHDP6LbGLpXgJPc2rV7FXmPBOzYqbf.X86uMqtnpeoK5p0ydUYltLGI9OdlM WiJVeQEZY.xTwTAscxW_eV4Sjv48Xb.TFj6WNLo70U_LCWr3jFPTVZJK6e.p4xaBaVnmJqRUyW3W i3Xv.JqOztGQrj7K.Q7vmg1wjnxQifMkJSv7cfqkC46NVxoJutKP5HActBTU0Byqc4QHH.AMMuVY 3QWxoOfUiGtVvlrkKtKU4sIyy2r_4gOUkxdICOxOrVJR8aAFS_4mh2B15LvXyecE3r6_2me7Z0F2 L9Oo32kXvne2_W1LS1dE9uygvR5zjlUVrLA8L2zUVu92ZBvPhncGHW0Q2yZltv.XQ5hyzfBltPgd tQrnMPBErABcEnigXLl.w2gb0XcjGm1r0SJbS.HXLwbQ1rOWkjpDHjCeZNi83642q0oqAHm2Xn96 N50E.d8Vd8m2PQiHMFwNF3G_2onldGih0aSaiQ0ZmkBPx_reMTfhcMJIgYSOe6G6.gSqSRE7M3Wy apmEktpfpTrUM6B3dOyMOkN_3TP.nHnrDdNMJsH.4H9JSkm0pVotGPQ3qUnhwsvAxonWZv5Isi3X SAodBrt1hI5S1CwslDbAkc4CpgAgmSZONBamFKmpc.xQjV9_7GivrHT9cxFmkeEfNq39gvzOGIkx uPXccSufctxkWDERgQdIuRhCb1dweMKXdGAcU6odzuiJt6eV0hNYilRMCVpbxTEL3UTMrZgtAsdA 3dRijQenXUDDvKanVfS5TUJy41qs4aPGicqaHCXBdKKEKrmlHG8z2l7LL_spgOmqxatwlPlhIq36 Ue7jWnUOD15YLpIvNY3zMQpjZDS6ZD2IEk_JRBCUVjETIW5OP.CLsoQ3rLD898I4ws286G6WoCzf BIPY7sty.ZKsHzWWRQjP9J_9D.gjLzsI6Mvdpx1DuLYOEH_p0T5ifAQNqazHALdiY9R0FYwGWUyO fw4QkyjuS3XMP32DXnEmr5o5dSKXoMzdiqW0uIfHYrt_K0QlgofUDxIMUddcm9WbLS8ys_0ZNjR1 hqPSh100_127iuUYCK6ffl0HmWtxnNWLiCjDkuv7rBLuAa6MxODHn.DgEysMt11LBjUEGQbnrWVt FunB4aPnPKDGcqAq1aXONzonVUCHErW0Yg28bdwU8by.4b4CrX8Zxu5DVt7W8_ggh_vFT1FazYGu yp51wHsU098yaU9qiv.xQJPQrcbqvllZsY_gr9gv6OzJVb6n4j17fBAsJ2WVv9Q-- Received: from sonic.gate.mail.ne1.yahoo.com by sonic308.consmr.mail.ne1.yahoo.com with HTTP; Wed, 30 Sep 2020 18:01:43 +0000 Received: by smtp415.mail.bf1.yahoo.com (VZM Hermes SMTP Server) with ESMTPA ID 52a3ccea29cec4154b645ca05f830988; Wed, 30 Sep 2020 18:01:39 +0000 (UTC) Subject: Re: [FlyRotary] Re: Mufflers To: Rotary motors in aircraft References: Message-ID: <4af68e23-ad78-80da-c773-02aff0c4e284@verizon.net> Date: Wed, 30 Sep 2020 14:01:36 -0400 User-Agent: Mozilla/5.0 (Windows NT 5.1; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: Content-Type: multipart/alternative; boundary="------------FD9EAA7F1B86ECEDF4DCA408" Content-Language: en-US X-Antivirus: Avast (VPS 200930-0, 09/30/2020), Outbound message X-Antivirus-Status: Clean X-Mailer: WebService/1.1.16718 mail.backend.jedi.jws.acl:role.jedi.acl.token.atz.jws.hermes.aol Apache-HttpAsyncClient/4.1.4 (Java/11.0.7) Content-Length: 86506 This is a multi-part message in MIME format. --------------FD9EAA7F1B86ECEDF4DCA408 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit 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. > > - Matt Boiteau > > > On Wed, Sep 30, 2020 at 5:38 AM lehanover lehanover@aol.com > > wrote: > > 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 Boiteau > > On Tue, Sep 29, 2020 at 3:02 PM Bobby J. Hughes > bhughes@qnsi.net > > wrote: > > 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/ > > - Matt Boiteau > > On Wed, Jul 8, 2020 at 2:35 PM Bobby J. Hughes > bhughes@qnsi.net > > wrote: > > 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. > > 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.30848/page-2#post-512762 > > > - Matt Boiteau > > On 2020-01-18 5:29:51 PM, Matt Boiteau > > 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.* > > - Matt Boiteau > > On 2020-01-07 12:19:23 AM, Matt Boiteau > mattboiteau@gmail.com > > > 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) > > > 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-stainless?variant=11067135556 > > *Error! Filename not specified.* > > Batwing tabs > > *Error! Filename not specified.* > > - Matt Boiteau > > On 2020-01-03 4:22:18 PM, Neil Unger > 12348ung@gmail.com > > > 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. > > On 1/4/2020 5:37 AM, Matt Boiteau > mattboiteau@gmail.com > wrote: > > 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.* > > - Matt Boiteau > > On 2019-12-28 11:03:42 AM, Finn > Lassen finn.lassen@verizon.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. > > - Matt Boiteau > > *Disclaimer* > > The information contained in this communication from > the sender is confidential. It is intended solely for > use by the recipient and others authorized to receive > it. If you are not the recipient, you are hereby > notified that any disclosure, copying, distribution or > taking action in relation of the contents of this > information is strictly prohibited and may be unlawful. > > This email has been scanned for viruses and malware, > and may have been automatically archived by *Mimecast > Ltd*, an innovator in Software as a Service (SaaS) for > business. Providing a *safer* and *more useful* place > for your human generated data. Specializing in; > Security, archiving and compliance. To find out more > Click Here . > > -- > Homepage: http://www.flyrotary.com/ > Archive and UnSub: > http://mail.lancaironline.net:81/lists/flyrotary/List.html > --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus --------------FD9EAA7F1B86ECEDF4DCA408 Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: 8bit
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.
 
- Matt Boiteau


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
 
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 Boiteau

On Tue, Sep 29, 2020 at 3:02 PM Bobby J. Hughes bhughes@qnsi.net <flyrotary@lancaironline.net> wrote:

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/  

- Matt Boiteau

 

 

On Wed, Jul 8, 2020 at 2:35 PM Bobby J. Hughes bhughes@qnsi.net <flyrotary@lancaironline.net> wrote:

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.

 

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.30848/page-2#post-512762

 

- Matt Boiteau

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.

 

- Matt Boiteau

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)


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-stainless?variant=11067135556

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Batwing tabs

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- Matt Boiteau

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.

On 1/4/2020 5:37 AM, Matt Boiteau mattboiteau@gmail.com wrote:

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?

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- Matt Boiteau

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).

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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. 

 

- Matt Boiteau

 

 

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