X-Junk-Score: 0 [] X-Cloudmark-Score: 0 [] X-Cloudmark-Analysis: v=2.3 cv=H+OlPNQi c=1 sm=1 tr=0 a=yTguEFSw6qQEeIF6PDpiVg==:117 a=jpOVt7BSZ2e4Z31A5e1TngXxSK0=:19 a=MeAgGD-zjQ4A:10 a=aOWVIxkx-zkA:10 a=pGLkceISAAAA:8 a=Ia-xEzejAAAA:8 a=eRLigfuSAAAA:8 a=7g1VtSJxAAAA:8 a=uUvVNMCypE7AGsf5QggA:9 a=QEXdDO2ut3YA:10 a=Qa1je4BO31QA:10 a=gvSQh4r-fQ0A:10 a=S0wkRrzPavQA:10 a=nvs_jtOC78UDUjZoYjIA:9 a=dDvsPJCOwnqfhLkX:21 a=Urk15JJjZg1Xo0ryW_k8:22 a=BfhXYjFvZD4iae-mNffo:22 a=grOzbf7U_OpcSX4AJOnl:22 From: "Andrew Martin andrew@martinag.com.au" Received: from mail-wr1-f47.google.com ([209.85.221.47] verified) by logan.com (CommuniGate Pro SMTP 6.2.14) with ESMTPS id 13191535 for flyrotary@lancaironline.net; Mon, 18 Nov 2019 21:44:31 -0500 Received-SPF: none receiver=logan.com; client-ip=209.85.221.47; envelope-from=andrew@martinag.com.au Received: by mail-wr1-f47.google.com with SMTP id b18so20510911wrj.8 for ; Mon, 18 Nov 2019 18:44:32 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=martinag-com-au.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to; bh=19QMysKZTHyfwoEMXD+yrrRB3evZ7hX6zuZYtWOiLrU=; b=OvhUOdpfZz4F5m8vuEa0vbJhPF/SjirNdwqv9v5bMCljLaE1lImKikhp1JlQpfslKU x0WAwnKaQMWtJvAG+pC+fPNb2k6JEF4gG5UzivnnVqkl3t3ZYV+BWm5YSzJha0DxEXhv OebzCKpw9aYT0R/IbeL0bA7DfIenbVkqr3hU2Ti+zi9xE4xMo5Z1pYtQeQ3ZrR+BnPXI ULl/+cestxEehUWsjwcImx1qkj9hKNt7OD2fVmtiVaBtJgF6AvN+lyUqLScoW+IU9PLr zlgRF2U5Nm7NzAAbUnp79qhMoEUvvcP9LsQE9f/lgUhiebbvBb2phhc55+gyrKNxl2GI NiHQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to; bh=19QMysKZTHyfwoEMXD+yrrRB3evZ7hX6zuZYtWOiLrU=; b=Fv8lU2a0Ht6XII6seDO4zJOX1vgK1TQbd3jaYmZvBitvGbTErjmjy4LAopqUOlowzF lSl1PMFtKQ1zzKNoJD4dMXfmav68mX6Vh32kHUu52b5F6LXdJU94anqMr7u4yVfdnVab qHQo2FHuJFc49d1KlpLNy6IlyUFPGNvNBvt+mKCP+BeotnOyKyM8d78i+iKf0/1RIh0Z N4qne0BIUuCiPtbTbCZX9s63j6hJbjONs719++8HG1BJy8VgNkhEZpESTDf1SPywlikY VAAds0VJeUFsJOev57iQX+OCfkWUIG1Zj2LxkJGWMh2O4UcZnJtvN4ANNpeIP6VehGEd QWtg== X-Gm-Message-State: APjAAAV+MzoGQMC4jKcZini1oIrw8j4barjT4wVShTSgmVKC6I9+ZtQq IAw08WwNrLkiuFl+mMHvFnwm2zrzAtzoucjPiqKjGRX9Eg== X-Google-Smtp-Source: APXvYqxPO+zXBxMfEx8GoCsP54taae9xg1Fc/CnkxEOOuCxwrwvfpO7pOMAGXKytCEmMU30l8lOmY4o24bOALZq1TIg= X-Received: by 2002:a5d:54cb:: with SMTP id x11mr35006287wrv.161.1574131453744; Mon, 18 Nov 2019 18:44:13 -0800 (PST) MIME-Version: 1.0 References: In-Reply-To: Date: Tue, 19 Nov 2019 10:44:00 +0800 Message-ID: Subject: Re: [FlyRotary] Re: Mufflers To: Rotary motors in aircraft Content-Type: multipart/alternative; boundary="000000000000216a960597aa0a3c" --000000000000216a960597aa0a3c Content-Type: text/plain; charset="UTF-8" Noise in cabin is acceptable. And I just use passive headset. Is a glass plane. makes big diff from aluminium so hard to compare with others Ive flown as to whether its airframe or engine related. Original exhaust exited at 90deg to cowl and was quieter than this one but did not flow as well. This time I turned the outlet about 30deg back so can actually see inside of pipe while flying. reckon I get a bit more noise because of this. Was quick to make but had to do in right sequence to ensure could get full welds everywhere needed. Just used 5mm mild steel for end plates, ms mig wire to weld 1.6mm 304ss pipes to manifold & end plates. Inner section of original mazda renesis manifold was not welded. Is just slip fit to allow movement. Now wish I took pic's as we put it together but really did not expect it to work as well as it does. Just the turbo by itself will tame the exhaust pulses lots on your plane if you use properly sized hot section rather than a wastegate. Lots of things can be done to reduce noise. On your current setup just tack welding a washer into end of pipe will help lots. Just keep increasing hole size until backpressure is not an issue. About 25-30mm out is all thats needed. If your smart enough you end up with a tuned exhaust. But that is way beyond me. On Tue, 19 Nov. 2019, 9:45 am Neil Unger 12348ung@gmail.com, < flyrotary@lancaironline.net> wrote: > Andrew, > > all very interesting, What noise do you get back in > the cab? bearable, loud or great? Neil. > On 11/19/2019 11:31 AM, Andrew Martin andrew@martinag.com.au wrote: > > Neil, I stumbled on a system that seems to work quite well. In my head I > think it works similar to an ANR headset where the noise is not muffled as > such but reflected to cancel it out. > Important bit is exhaust enters & exits at same end. In my case I used a > 65mm ss pipe inside a 100mm pipe about 150mm long, but longer would be > better again as outlet on outer pipe does see some holes on inner pipe so > noise has direct escape path. 65 mm pipe has 10mm holes with about twice > area of pipe to try to minimize back pressure. > Theory is that exhaust pulses are broken into smaller bits as they see > holes in inner pipe, but then hit the blanked off end and are reflected > just like in ANR. Not sure if this is correct or not, but it seems to work > in use quite well. > My exhaust system is quite short as tailpipe exits just behind prop > similar to PT6 turboprop. I made exit pipe from 65mm also but think smaller > may be better as I think the exhaust gas flows much better after the pulses > are broken up. > Andrew > > On Tue, 19 Nov 2019 at 5:20 am, Neil Unger 12348ung@gmail.com < > flyrotary@lancaironline.net> wrote: > >> Attn Todd Bartrim, >> >> When in doubt check the >> instruction book!! I finally checked the archives to find that Todd you >> are way in front of me. I am definitely going to put a turbo on my >> renesis, but am still looking for a muffler. Depending on what Lynn >> suggestes, but your experience with the spintech or your latest version >> is appreciated. Do you have any tests with a decibel meter? My exhaust >> noise is just too loud, fine for me but passengers do not exactly que up >> for another ride. >> >> So design starts all over again, but I do have another engine to play >> with to keep mine in the air while I experiment. Here again Todd you >> have the electric water pump --- thoughts? >> >> Neil. >> >> >> -- >> Homepage: http://www.flyrotary.com/ >> Archive and UnSub: >> http://mail.lancaironline.net:81/lists/flyrotary/List.html >> > -- > Regards Andrew Martin Martin Ag > > --000000000000216a960597aa0a3c Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
Noise in cabin is acceptable. And I just use passive head= set. Is a glass plane. makes big diff from aluminium so hard to compare wit= h others Ive flown as to whether its airframe or engine related.
Original exhaust exited at 90deg to cowl and was quieter than this o= ne but did not flow as well. This time I turned the outlet about 30deg back= so can actually see inside of pipe while flying. reckon I get a bit more n= oise because of this.
Was quick to make but had to d= o in right sequence to ensure could get full welds everywhere needed. Just = used 5mm mild steel for end plates, ms mig wire to weld 1.6mm 304ss pipes t= o manifold & end plates.
Inner section of origin= al mazda renesis manifold was not welded. Is just slip fit to allow movemen= t.=C2=A0
Now wish I took pic's as we put it toge= ther but really did not expect it to work as well as it does.
Just the turbo by itself will tame the exhaust pulses lots on you= r plane if you use properly sized hot section rather than a wastegate.
Lots of things can be done to reduce noise. On your curr= ent setup just tack welding a washer into end of pipe will help lots. Just = keep increasing hole size until backpressure is not an issue. About 25-30mm= out is all thats needed. If your smart enough you end up with a tuned exha= ust. But that is way beyond me.

<= div dir=3D"ltr" class=3D"gmail_attr">On Tue, 19 Nov. 2019, 9:45 am Neil Ung= er 12348ung@gmail.com, <flyrotary@lancaironline.net>= ; wrote:
=20 =20 =20

Andrew,

=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 all very interesting,=C2=A0 What= noise do you get back in the cab?=C2=A0 bearable, loud or great?=C2=A0 Neil.

On 11/19/2019 11:31 AM, Andrew Martin andrew@martinag.com.au wrote:
=20
Neil, I stumbled on a system that seems to work quite=C2=A0well. In my head I think it works similar to an ANR headset where the noise is not muffled as such but reflected to cancel it out.
Important bit is exhaust enters & exits at same end. In my case I used a 65mm ss pipe inside a 100mm pipe about 150mm long, but longer would be better again as outlet on outer pipe does see some holes on inner pipe so noise has direct escape path. 65 mm pipe has 10mm holes with about twice area of pipe to try to minimize back pressure.
Theory is that exhaust pulses are broken into smaller bits as they see holes in inner pipe, but then hit the blanked off end and are reflected just like in ANR. Not sure if this is correct or not, but it seems to work in use quite well.
My exhaust system is quite short as tailpipe exits just behind prop similar to PT6 turboprop. I made exit pipe from 65mm also but think smaller may be better as I think the exhaust gas flows much better after the pulses are broken up.=C2=A0
Andrew

On Tue, 19 Nov 2019 at 5:20 am, Neil Unger 12348ung@gmail.com <flyrotary@lancaironline.net> wrote:
Attn Todd Bartrim,

=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0 When in doubt check the
instruction book!!=C2=A0 I finally checked the archives to fi= nd that Todd you
are way in front of me.=C2=A0 I am definitely going to put a turbo on my
renesis, but am still looking for a muffler. Depending on what Lynn
suggestes, but your experience with the spintech or your latest version
is appreciated.=C2=A0 Do you have any tests with a decibel meter?=C2=A0 My exhaust
noise is just too loud, fine for me but passengers do not exactly que up
for another ride.

So design starts all over again, but I do have another engine to play
with to keep mine in the air while I experiment.=C2=A0=C2=A0= =C2=A0 Here again Todd you
have the electric water pump --- thoughts?

Neil.


--
Homepage:=C2=A0 http://www.flyrotary.com/
Archive and UnSub:=C2=A0 =C2=A0http://mail.lancaironline.net:81/lists/flyrotary/List.html
--
Regards Andrew Martin Martin Ag
--000000000000216a960597aa0a3c--