X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from omr-d06.mx.aol.com ([205.188.109.203] verified) by logan.com (CommuniGate Pro SMTP 6.0.8) with ESMTPS id 6693821 for flyrotary@lancaironline.net; Sun, 19 Jan 2014 12:05:59 -0500 Received-SPF: pass receiver=logan.com; client-ip=205.188.109.203; envelope-from=shipchief@aol.com Received: from mtaomg-mbe01.mx.aol.com (mtaomg-mbe01.mx.aol.com [172.26.254.175]) by omr-d06.mx.aol.com (Outbound Mail Relay) with ESMTP id 8F78C70004127 for ; Sun, 19 Jan 2014 12:05:24 -0500 (EST) Received: from core-dda001b.r1000.mail.aol.com (core-dda001.r1000.mail.aol.com [172.29.52.1]) by mtaomg-mbe01.mx.aol.com (OMAG/Core Interface) with ESMTP id 53ADA38000082 for ; Sun, 19 Jan 2014 12:05:24 -0500 (EST) References: To: flyrotary@lancaironline.net Subject: Re: [FlyRotary] Re: muffler for Renesis? In-Reply-To: X-MB-Message-Source: WebUI MIME-Version: 1.0 From: shipchief@aol.com X-MB-Message-Type: User Content-Type: multipart/alternative; boundary="--------MB_8D0E34FC7080360_2384_6286_webmail-d163.sysops.aol.com" X-Mailer: AOL Webmail 38289-STANDARD Received: from 184.78.169.203 by webmail-d163.sysops.aol.com (205.188.252.87) with HTTP (WebMailUI); Sun, 19 Jan 2014 12:05:24 -0500 Message-Id: <8D0E34FC6F759C0-2384-1CBF@webmail-d163.sysops.aol.com> X-Originating-IP: [184.78.169.203] Date: Sun, 19 Jan 2014 12:05:24 -0500 (EST) x-aol-global-disposition: G DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mx.aol.com; s=20121107; t=1390151124; bh=tPrwYqpPOAAIJvdQpdtziNRpiCy3Mi3iWVt12xYUilo=; h=From:To:Subject:Message-Id:Date:MIME-Version:Content-Type; b=pd79A4I0LsslMRTAYBkqebTJ6lOx8FS1b/I3nFrh99tGHK21k9V5yssynUHP4a4br HJrt5fV7PrYC4FlK9Mh6wc+Pc5r9N2apHqkPMcCj/D1PSk9fSSSO3RJaVkQMm05q5r 7gk4QL+MaGlO/BHYCmEJtC2Dk17lgCsnzht1pp/c= x-aol-sid: 3039ac1afeaf52dc05d41cd9 This is a multi-part message in MIME format. ----------MB_8D0E34FC7080360_2384_6286_webmail-d163.sysops.aol.com Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="us-ascii" Charlie; The turbo does strip off a lot of noise. I understand the unmuffled 13b wil= l rip your ears off! ;) Still, at power above 5000 RPM it is too loud for me in the cockpit, and I'= m wearing a Flightcom copy of a David Clark headset.=20 I'm planning to download a Decibel Meter app for my IPhone once I remember = my password.... I'm leaning toward the SPLnFFT app, which has a good rating. It will compare the sound volume and quality of my future muffler attempts. -----Original Message----- From: Charlie England To: Rotary motors in aircraft Sent: Sat, Jan 18, 2014 12:00 pm Subject: [FlyRotary] Re: muffler for Renesis? =20 =20 Just to be clear, I'm looking at the H P resonator, not the full size = muffler. http://www.summitracing.com/parts/hsh-12412400/overview/ =20 I would either use that, or the aeroturbine without the built-in = resonator: http://www.aeroexhaust.com/mufflers/aero-exhaust-at2525.html =20 If you've never heard Dennis Havarlah's Renesis in his RV-7A, you = can barely hear the engine. Most of what you hear is prop. He uses t= he stock Renesis exhaust manifold, which feeds at a tangent into a lar= ge diameter 'swirl can', which has a tangential exit into the H P reso= nator. Note that *all* of that is within the cowl. There is a lot of e= mpirical evidence that the extra mass and damping material between the= layers of metal in the stock manifold does a lot to kill the offensiv= e odd-harmonics in the exhaust tone. Keeping everything inside the cow= l seems to help a lot, as well. My belief is that the high freq audio = energy that survives & radiates off the manifold & muffler gets damped= further by the cowl, so what's left is a much more pleasing, lower fr= equency spectrum sound. =20 I would have expected your turbo to strip off most of the high f= req energy. Can you find a sound level meter to quantify what you're h= earing in the cockpit? (And don't forget, the prop can be very noisy, = too. If you're running a 2.1 ratio drive & turning a fairly large diam= eter prop, that may be the source of some of your noise.) =20 Charlie =20 On 1/18/2014 1:10 PM, shipchief@aol.com wrote: =20 =20 =20 I'm running a turbo, and it's still pretty loud. After I take off = and climb out, I find myself reducing power to reduce the sound le= vel.=20 =20 It's pretty quiet at idle and during ground operations, but above = 5000 RPM which is above 34"Hg manifold pressure, it's too loud ins= ide the cockpit for me. =20 My TO4 turbine outlet faces aft into a reducer cone transition to = a 2" pipe. This pipe has two 90 degree bends and lets out parallel= to the air exit ramp on the bottom of the fuselage of my RV-8. =20 I'm thinking the sound waves need to be directed away from the fus= elage skin, so I ordered a slip on exhaust turndown tip (Walker 41= 420) and a lap joint band clamp. Even with that, I would like to be a good neighbor. I'm = planning to flatten the turndown to a 1" rectangular outlet, and d= rill 18 ea 3/8" holes in the down facing flat. Then use a 3/8" dia= meter rod to bend each hole into a slightly rear facing shape. =20 I believe the term is "Piccolo Pipe". I have a Hushpower muffler, which I bought after Tracy made = his first report on it. I just checked it out (box is pretty d= usty, time must have slipped by somehow?) That thing weighs alot. = Also, the idea that the 'innards' might break loose and clog the o= utlet seems a bit scarey. =20 The Aeroturbine would look better hanging under the fuselage tho- = if I end up needing a real muffler. (might need to clamp on 4 big = fins at the back for aerodynamic guidance + asthetics?) =20 =20 -----Original Message----- From: Charlie England To: Rotary motors in aircraft Sent: Sat, Jan 18, 2014 9:23 am Subject: [FlyRotary] Re: muffler for Renesis? =20 =20 =20 Thanks, Mark. I discovered that after I sent the previous message. Their=20 web site seems to have a somewhat random 'organization'. Is the non-res model only 20" overall, as they describe? That would make=20 it only slightly longer than the H.P. resonator that Dennis is using, &=20 since it appears to be only a perforated tube in the main cylinder, it=20 should survive much better than anything with actual baffles and/or packing= . Charlie On 1/18/2014 9:38 AM, Mark Steitle wrote: > Charlie, > They stock two types, one with packing, one without. The one with packin= g is=20 their "resonator"model, and it is longer than the non-res model. I bought = the=20 non-res model as I figured the packing was only temporary. I have not inst= alled=20 it yet, so no flight report. > > Mark > > Sent from my iPad > >> On Jan 18, 2014, at 8:54 AM, Charlie England wrot= e: >> >> Thanks, Tracy; it's good news that it is both quiet and survives. Didn't= =20 realize that the aeroturbine had packing in it. If it performs as well as, = or=20 better than the hushpower, I may give it a shot. It's actually a bit cheape= r=20 than the h.p. resonator. >> >> Charlie >> >>> On 1/17/2014 10:53 AM, Tracy wrote: >>> The aero turbine sounded better than the Hushpower II but both change = in=20 tone over time, probably due to packing deteriorating. Still, the AT was = the=20 best after they stabilized. >>> >>> Tracy >>> >>> Sent from my iPad >>> >>>> On Jan 17, 2014, at 11:06, Charlie England wrot= e: >>>> >>>> Time to order a muffler. My goal is to keep it inside the cowl (RV-7).= I=20 know, I know, but it looks better, and more important, it *sounds* better. >>>> >>>> I believe that Dennis H. used this: >>>> http://www.summitracing.com/parts/hsh-12412400/overview/ >>>> I know it sounds great. Dennis, do you remember the weight of just the= =20 resonator? >>>> >>>> I know that Tracy is running an Aeroturbine (weight: 6 lbs on the 20B = in=20 the RV-8, & has talked about how good it sounds: >>>> http://www.aeroexhaust.com/mufflers/aero-exhaust-at2525.html >>>> >>>> They are roughly the same size and price, so I'm wondering how the=20 Aeroturbine will compare in performance (meaning: killing the harsh harmoni= cs of=20 the rotary). >>>> >>>> Tracy, you might be the only person who's heard both on a rotary. Base= d on=20 your 20B experience, is it likely to work better than the Hushpower Resonat= or on=20 a Renesis? I'll be using a manifold/transition pipe similar to Dennis' setu= p to=20 keep everything inside the cowl. >>>> >>>> Thanks, >>>> >>>> Charlie >>>> >>>> >>>> >>>> -- >>>> Homepage: http://www.flyrotary.com/ >>>> Archive and UnSub: http://mail.lancaironline.net:81/lists/flyrotary/= List.html >>> -- >>> Homepage: http://www.flyrotary.com/ >>> Archive and UnSub: http://mail.lancaironline.net:81/lists/flyrotary/L= ist.html >> >> -- >> Homepage: http://www.flyrotary.com/ >> Archive and UnSub: http://mail.lancaironline.net:81/lists/flyrotary/Li= st.html > -- > Homepage: http://www.flyrotary.com/ > Archive and UnSub: http://mail.lancaironline.net:81/lists/flyrotary/Lis= t.html -- Homepage: http://www.flyrotary.com/ Archive and UnSub: http://mail.lancaironline.net:81/lists/flyrotary/List.= html =20 =20 =20 =20 =20 ----------MB_8D0E34FC7080360_2384_6286_webmail-d163.sysops.aol.com Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset="us-ascii"
Charlie;
The turbo does strip off a lot of noise. I understand the unmuffled 13= b will rip your ears off!  ;)
Still, at power above 5000 RPM it is too loud for me in the cockpit, a= nd I'm wearing a Flightcom copy of a David Clark headset.
I'm planning to download a Decibel Meter app for my IPhone once I reme= mber my password....
I'm leaning toward the SPLnFFT app, which has a good rating.
It will compare the sound volume and quality of my future muffler = ;attempts.
 
-----Original Message-----
From: Charlie England <ceengland7@gmail.com>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Sent: Sat, Jan 18, 2014 12:00 pm
Subject: [FlyRotary] Re: muffler for Renesis?

=20 =20 =20 =20
=20
Just to be clear, I'm looking at the H P resonator, not the full size muffler.
http://www.summitracing.c= om/parts/hsh-12412400/overview/

 I would either use that, or the aeroturbine without the built-i= n resonator:
http://www.aeroexhaus= t.com/mufflers/aero-exhaust-at2525.html

If you've never heard Dennis Havarlah's Renesis in his RV-7A, you can barely hear the engine. Most of what you hear is prop. He uses the stock Renesis exhaust manifold, which feeds at a tangent into a large diameter 'swirl can', which has a tangential exit into the H P resonator. Note that *all* of that is within the cowl. There is a lot of empirical evidence that the extra mass and damping material between the layers of metal in the stock manifold does a lot to kill the offensive odd-harmonics in the exhaust tone. Keeping everything inside the cowl seems to help a lot, as well. My belief is that the high freq audio energy that survives & radiates off the manifold & muffler gets damped further by the cowl, so what's left is a much more pleasing, lower frequency spectrum sound.

I would have expected your turbo to strip off most of the high freq energy. Can you find a sound level meter to quantify what you're hearing in the cockpit? (And don't forget, the prop can be very noisy, too. If you're running a 2.1 ratio drive & turning a fairly large diameter prop, that may be the source of some of your noise.)

Charlie

On 1/18/2014 1:10 PM, shipchief@aol.com wrote:
=20
I'm running a turbo, and it's still pretty loud. After I take off and climb out, I find myself reducing power to reduce the sound level.
=20
It's pretty quiet at idle and during ground operations, but above 5000 RPM which is above 34"Hg manifold pressure, it's too loud inside the cockpit for me.
=20
My TO4 turbine outlet faces aft into a reducer cone transition to a 2" pipe. This pipe has two 90 degree bends and lets out parallel to the air exit ramp on the bottom of the fuselage of my RV-8.
=20
I'm thinking the sound waves need to be directed away from the fuselage skin, so I ordered a slip on exhaust turndown tip (Walker 41420) and a lap joint band clamp.
Even with that, I would like to be a good neighbor. I'm planning to flatten the turndown to a 1" rectangular outlet, and drill 18 ea 3/8" holes in the down facing flat. Then use a 3/8" diameter rod to bend each hole into a slightly rear facing shape.
=20
I believe the term is "Piccolo Pipe".
I have a Hushpower muffler, which I bought after Tracy made his first report on it. I just checked it out (box is pretty dusty, time must have slipped by somehow?) That thing weighs alot. Also, the idea that the 'innards' might break loose and clog the outlet seems a bit scarey.
=20
The Aeroturbine would look better hanging under the fuselage tho- if I end up needing a real muffler. (might need to clamp on 4 big fins at the back for aerodynamic guidance + asthetics?)
=20
-----Original Message-----
From: Charlie England <ceengland7@gmail.com>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Sent: Sat, Jan 18, 2014 9:23 am
Subject: [FlyRotary] Re: muffler for Renesis?

=20 
Thanks, Mark. I discovered t=
hat after I sent the previous message. Their=20
web site seems to have a somewhat random 'organization'.

Is the non-res model only 20" overall, as they describe? That would make=20
it only slightly longer than the H.P. resonator that Dennis is using, &=
=20
since it appears to be only a perforated tube in the main cylinder, it=20
should survive much better than anything with actual baffles and/or packing=
.

Charlie

On 1/18/2014 9:38 AM, Mark Steitle wrote:
> Charlie,
> They stock two types, one with packing, one without.  The one with pac=
king is=20
their "resonator"model, and it is longer than the non-res model.  I bought =
the=20
non-res model as I figured the packing was only temporary.  I have not inst=
alled=20
it yet, so no flight report.
>
> Mark
>
> Sent from my iPad
>
>> On Jan 18, 2014, at 8:54 AM, Charlie England <ceengland7@gmail.com> wrote:
>>
>> Thanks, Tracy; it's good news that it is both quiet and survives. =
Didn't=20
realize that the aeroturbine had packing in it. If it performs as well as, =
or=20
better than the hushpower, I may give it a shot. It's actually a bit cheape=
r=20
than the h.p. resonator.
>>
>> Charlie
>>
>>> On 1/17/2014 10:53 AM, Tracy wrote:
>>> The aero turbine sounded better than the Hushpower II  but bot=
h change in=20
tone over time, probably due to packing deteriorating.   Still, the AT was =
the=20
best after they stabilized.
>>>
>>> Tracy
>>>
>>> Sent from my iPad
>>>
>>>> On Jan 17, 2014, at 11:06, Charlie England <ceengland7@gmail.com> wrote:
>>>>
>>>> Time to order a muffler. My goal is to keep it inside the =
cowl (RV-7). I=20
know, I know, but it looks better, and more important, it *sounds* better.
>>>>
>>>> I believe that Dennis H. used this:
>>>> http://www.summitracing.com/parts/hsh-12412400=
/overview/
>>>> I know it sounds great. Dennis, do you remember the weight=
 of just the=20
resonator?
>>>>
>>>> I know that Tracy is running an Aeroturbine (weight: 6 lbs=
 on the 20B in=20
the RV-8, & has talked about how good it sounds:
>>>> http://www.aeroexhaust.com/mufflers/aero-e=
xhaust-at2525.html
>>>>
>>>> They are roughly the same size and price, so I'm wondering=
 how the=20
Aeroturbine will compare in performance (meaning: killing the harsh harmoni=
cs of=20
the rotary).
>>>>
>>>> Tracy, you might be the only person who's heard both on a =
rotary. Based on=20
your 20B experience, is it likely to work better than the Hushpower Resonat=
or on=20
a Renesis? I'll be using a manifold/transition pipe similar to Dennis' setu=
p to=20
keep everything inside the cowl.
>>>>
>>>> Thanks,
>>>>
>>>> Charlie
>>>>
>>>>
>>>>
>>>> --
>>>> Homepage:  http://www.flyrotary.com/
>>>> Archive and UnSub:   http://mail.lancaironli=
ne.net:81/lists/flyrotary/List.html
>>> --
>>> Homepage:  http://www.flyrotary.com/
>>> Archive and UnSub:   http://mail.lancaironline.n=
et:81/lists/flyrotary/List.html
>>
>> --
>> Homepage:  http://www.flyrotary.com/
>> Archive and UnSub:   http://mail.lancaironline.net:8=
1/lists/flyrotary/List.html
> --
> Homepage:  htt=
p://www.flyrotary.com/
> Archive and UnSub:   http://mail.lancaironline.net:81/li=
sts/flyrotary/List.html


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