X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mail-ob0-f177.google.com ([209.85.214.177] verified) by logan.com (CommuniGate Pro SMTP 6.0.8) with ESMTPS id 6694149 for flyrotary@lancaironline.net; Sun, 19 Jan 2014 18:36:32 -0500 Received-SPF: pass receiver=logan.com; client-ip=209.85.214.177; envelope-from=msteitle@gmail.com Received: by mail-ob0-f177.google.com with SMTP id wp18so4499316obc.36 for ; Sun, 19 Jan 2014 15:35:57 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=subject:references:from:content-type:in-reply-to:message-id:date:to :content-transfer-encoding:mime-version; bh=DSVXGS+bdeAZROxdCkZ9rSZdob7rKhWm1WNnm0Yy9Rw=; b=EaMbu0uRxaxnKnJeBK7WJVLiQRRAuj2454tlDMlVES2nN33ofw71jt1tuLd1XgzgfF beoXx3KQ1WPL0KmDwB3mEgE9IkbCAs1+GM9KymS/C1U8uWwvDqMp1yMgcJpgxipBa4fO MpX/50w6z104wcL2A/LtuOFCW4maSXNMhCJu3THiUlVBo+wpcGP7Bsj2dSews1JTpa4k 0Q2FbKmgV5gY4mAe4JcLjsFBbTaYxzxj2iDHGE+CYSXcP7k7K7V03gW9rWB1zEPYJYCK uHvg52HPuZcl2yhE6GYnmCGhO3Ti7X13yuFGJKcCqSSTB7s37w9SSDQDMo3SH24UoFQC 0a6g== X-Received: by 10.182.49.166 with SMTP id v6mr13011689obn.13.1390174557604; Sun, 19 Jan 2014 15:35:57 -0800 (PST) Return-Path: Received: from [192.168.1.102] (cpe-173-172-120-114.austin.res.rr.com. [173.172.120.114]) by mx.google.com with ESMTPSA id qh4sm23539121obc.4.2014.01.19.15.35.56 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Sun, 19 Jan 2014 15:35:56 -0800 (PST) Subject: Re: [FlyRotary] Re: muffler for Renesis? References: From: Mark Steitle Content-Type: multipart/alternative; boundary=Apple-Mail-3E35572A-B960-408A-BC48-11E8FBA5C2E6 X-Mailer: iPad Mail (11B554a) In-Reply-To: Message-Id: <1B279F63-B376-43B7-A6A0-5659F525920F@gmail.com> Date: Sun, 19 Jan 2014 17:35:58 -0600 To: Rotary motors in aircraft Content-Transfer-Encoding: 7bit Mime-Version: 1.0 (1.0) --Apple-Mail-3E35572A-B960-408A-BC48-11E8FBA5C2E6 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable I recently flew without sound deadening pad and carpet, which has a half-inc= h layer of sound padding glued to the underside. It was so loud in the cabi= n that I could barely make my radio calls over the exhaust noise. Reinstall= ed the soundproofing prior to my next flight, the difference was night and d= ay. No more flying without soundproofing and carpeting. For the record, I'm= running a DNA muffler and wear a Zulu headset. Mark Sent from my iPad > On Jan 19, 2014, at 3:15 PM, Charlie England wrote:= >=20 > A phone-based spectrum analyzer could be useful to see the frequencies of t= he noise, but at a/c noise levels, the microphone in the phone is almost alw= ays going to be badly overdriven. Even a cheap dB meter would work a lot bet= ter. >=20 > If your headset is a traditional passive design, I'd strongly recommend up= grading to either an active noise cancellation model or an in-ear model like= Bill is using. I gave up on passive headsets over a decade ago, for *any* a= viation use. Lightspeed's active designs are good, & Bill can tell you wheth= er the in-ear model is good. I use=20 > http://www.quiettechnologies.com/ > I really like them because there's no 'clamp' on my head, no batteries req= uired, & they block roughly the same noise as even the better active noise c= ancelling headsets. They're also the cheapest, as far as I know. If you can t= olerate foam earplugs, they might be worth a listen. >=20 > Charlie >=20 >> On 1/19/2014 11:53 AM, Bill Bradburry wrote: >> I have the free Decibel Ultra, but it only goes to 120 db. Not nearly hi= gh enough! >> =20 >> My plane doesn=E2=80=99t seem that loud inside in flight although people o= n the ground recognize me from afar. You might consider some soundproofing o= n that aluminum skin around the exit of the exhaust. My plane is fiberglass= and inside in flight it sounds like Tracy describes it as a hum. >> =20 >> I use the Lightspeed Mach 1 headset. It is the in the ear headset and do= esn=E2=80=99t have noise cancelling, but seems to work as well as those that= do. >> =20 >> From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On B= ehalf Of shipchief@aol.com >> Sent: Sunday, January 19, 2014 12:05 PM >> To: Rotary motors in aircraft >> Subject: [FlyRotary] Re: muffler for Renesis? >> =20 >> Charlie; >> The turbo does strip off a lot of noise. I understand the unmuffled 13b w= ill 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. >> I'm planning to download a Decibel Meter app for my IPhone once I remembe= r 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 attempt= s. >> =20 >> -----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 >> Just to be clear, I'm looking at the H P resonator, not the full size muf= fler. >> http://www.summitracing.com/parts/hsh-12412400/overview/ >>=20 >> I would either use that, or the aeroturbine without the built-in resonat= or: >> 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 bar= ely hear the engine. Most of what you hear is prop. He uses the stock Renesi= s exhaust manifold, which feeds at a tangent into a large diameter 'swirl ca= n', which has a tangential exit into the H P resonator. Note that *all* of t= hat is within the cowl. There is a lot of empirical evidence that the extra m= ass and damping material between the layers of metal in the stock manifold d= oes a lot to kill the offensive odd-harmonics in the exhaust tone. Keeping e= verything inside the cowl seems to help a lot, as well. My belief is that th= e 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, lo= wer frequency spectrum sound. >>=20 >> I would have expected your turbo to strip off most of the high freq energ= y. Can you find a sound level meter to quantify what you're hearing in the c= ockpit? (And don't forget, the prop can be very noisy, too. If you're runnin= g a 2.1 ratio drive & turning a fairly large diameter prop, that may be the s= ource of some of your noise.) >>=20 >> Charlie >>=20 >>> On 1/18/2014 1:10 PM, shipchief@aol.com wrote: >>> I'm running a turbo, and it's still pretty loud. After I take off and cl= imb out, I find myself reducing power to reduce the sound level. >>> It's pretty quiet at idle and during ground operations, but above 5000 R= PM which is above 34"Hg manifold pressure, it's too loud inside the cockpit f= or me. >>> My TO4 turbine outlet faces aft into a reducer cone transition to a 2" p= ipe. 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. >>> I'm thinking the sound waves need to be directed away from the fuselage s= kin, so I ordered a slip on exhaust turndown tip (Walker 41420) and a lap jo= int band clamp. >>> Even with that, I would like to be a good neighbor. I'm planning to flat= ten the turndown to a 1" rectangular outlet, and drill 18 ea 3/8" holes in t= he down facing flat. Then use a 3/8" diameter rod to bend each hole into a s= lightly rear facing shape. >>> I believe the term is "Piccolo Pipe". >>> I have a Hushpower muffler, which I bought after Tracy made his first re= port on it. I just checked it out (box is pretty dusty, time must have slipp= ed by somehow?) That thing weighs alot. Also, the idea that the 'innards' mi= ght break loose and clog the outlet seems a bi= t scarey. >>> The Aeroturbine would look better hanging under the fuselage tho- if I e= nd up needing a real muffler. (might need to clamp on 4 big fins at the back= for aerodynamic guidance + asthetics?) >>> -----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 >>> Thanks, Mark. I discovered that after I sent the previous message. Their= =20 >>> web site seems to have a somewhat random 'organization'. >>> =20 >>> 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 pack= ing. >>> =20 >>> Charlie >>> =20 >>> 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 boug= ht the=20 >>> non-res model as I figured the packing was only temporary. I have not i= nstalled=20 >>> it yet, so no flight report. >>> >=20 >>> > Mark >>> >=20 >>> > Sent from my iPad >>> >=20 >>> >> On Jan 18, 2014, at 8:54 AM, Charlie England w= rote: >>> >>=20 >>> >> Thanks, Tracy; it's good news that it is both quiet and survives. Did= n't=20 >>> realize that the aeroturbine had packing in it. If it performs as well a= s, or=20 >>> better than the hushpower, I may give it a shot. It's actually a bit che= aper=20 >>> than the h.p. resonator. >>> >>=20 >>> >> Charlie >>> >>=20 >>> >>> On 1/17/2014 10:53 AM, Tracy wrote: >>> >>> The aero turbine sounded better than the Hushpower II but both chan= ge in=20 >>> tone over time, probably due to packing deteriorating. Still, the AT w= as the=20 >>> best after they stabilized. >>> >>>=20 >>> >>> Tracy >>> >>>=20 >>> >>> Sent from my iPad >>> >>>=20 >>> >>>> On Jan 17, 2014, at 11:06, Charlie England w= rote: >>> >>>>=20 >>> >>>> 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* bette= r. >>> >>>>=20 >>> >>>> 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 t= he=20 >>> resonator? >>> >>>>=20 >>> >>>> I know that Tracy is running an Aeroturbine (weight: 6 lbs on the 2= 0B in=20 >>> the RV-8, & has talked about how good it sounds: >>> >>>> http://www.aeroexhaust.com/mufflers/aero-exhaust-at2525.html >>> >>>>=20 >>> >>>> They are roughly the same size and price, so I'm wondering how the=20= >>> Aeroturbine will compare in performance (meaning: killing the harsh harm= onics of=20 >>> the rotary). >>> >>>>=20 >>> >>>> Tracy, you might be the only person who's heard both on a rotary. B= ased on=20 >>> your 20B experience, is it likely to work better than the Hushpower Reso= nator on=20 >>> a Renesis? I'll be using a manifold/transition pipe similar to Dennis' s= etup to=20 >>> keep everything inside the cowl. >>> >>>>=20 >>> >>>> Thanks, >>> >>>>=20 >>> >>>> Charlie >>> >>>>=20 >>> >>>>=20 >>> >>>>=20 >>> >>>> -- >>> >>>> Homepage: http://www.flyrotary.com/ >>> >>>> Archive and UnSub: http://mail.lancaironline.net:81/lists/flyrota= ry/List.html >>> >>> -- >>> >>> Homepage: http://www.flyrotary.com/ >>> >>> Archive and UnSub: http://mail.lancaironline.net:81/lists/flyrotar= y/List.html >>> >>=20 >>> >> -- >>> >> 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/= List.html >>> =20 >>> =20 >>> -- >>> Homepage: http://www.flyrotary.com/ >>> Archive and UnSub: http://mail.lancaironline.net:81/lists/flyrotary/Li= st.html >=20 --Apple-Mail-3E35572A-B960-408A-BC48-11E8FBA5C2E6 Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: quoted-printable
I recently flew without sound deadenin= g pad and carpet, which has a half-inch layer of sound padding glued to the u= nderside.  It was so loud in the cabin that I could barely make my radi= o calls over the exhaust noise.  Reinstalled the soundproofing prior to= my next flight, the difference was night and day. No more flying without so= undproofing and carpeting.  For the record, I'm running a DNA muffler a= nd wear a Zulu headset.

Mark

Sent from my iP= ad

On Jan 19, 2014, at 3:15 PM, Charlie England <ceengland7@gmail.com> wrote:

=20 =20 =20
A phone-based spectrum analyzer could be useful to see the frequencies of the noise, but at a/c noise levels, the microphone in the phone is almost always going to be badly overdriven. Even a cheap dB meter would work a lot better.

If your headset is a traditional passive design, I'd strongly recommend upgrading to either an active noise cancellation model or an in-ear model like Bill is using. I gave up on passive headsets over a decade ago, for *any* aviation use. Lightspeed's active designs are good, & Bill can tell you whether the in-ear model is good. I use
http://www.quiettechnologies.com/
I really like them because there's no 'clamp' on my head, no batteries required, & they block roughly the same noise as even the better active noise cancelling headsets. They're also the cheapest, as far as I know. If you can tolerate foam earplugs, they might be worth a listen.

Charlie

On 1/19/2014 11:53 AM, Bill Bradburry wrote:

I have the free Decibel Ultra, but it only goes to 120 db.  Not nearly high enough!=

 

My plane doesn=E2=80=99t seem that loud inside in flight although people on the ground recognize me from afar.  You might consider some soundproofing on that aluminum skin around the exit of the exhaust.  My plane is fiberglass and inside in flight it sounds like Tracy describes it as a hum.

 

I use the Lightspeed Mach 1 headset.  It is the in the ear headset and doesn=E2=80=99t have no= ise cancelling, but seems to work as well as those that do.

 

<= span style=3D"font-size:10.0pt; font-family:Tahoma;font-weight:bold">From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of shipchief@aol.com
Sent: Sunday, January 19, 2014 12:05 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: muffler for Renesis?

 

Charlie;

The turbo does strip off a lot of noise. I understand the unmuffled 13b will 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.

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 <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?

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

 I would either use that, or the aeroturbin= e without the built-in resonator:
http://w= ww.aeroexhaust.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:

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.

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.

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.

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.

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.

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?)

-----Original Message-----
From: Charlie England <ceengland7@gmail.com> To: Rotary motors in aircraft <flyrotar= y@lancaironline.net>
Sent: Sat, Jan 18, 2014 9:23 am
Subject: [FlyRotary] Re: muffler for Renesis?

Thanks, Mark. I discovered that after I sent the previous message. T=
heir 
web site seems to have a somewhat random 'organization'.=

 
Is the non-res model only 20" overall, as they describe? That would=
 make 
it only slightly longer than the H.P. resonator that Dennis is usin=
g, & 
since it appears to be only a perforated tube in the main cylinder,=
 it 
should survive much better than anything with actual baffles and/or=
 packing.
 
Charlie
 
On 1/18/2014 9:38 AM, Mark Steitle wrote:<=
/tt>
> Charlie,
> They stock two types, one with packing, one without.  The=
 one with packing is 
their "resonator"model, and it is longer than the non-res model.&nb=
sp; I bought the 
non-res model as I figured the packing was only temporary.  I h=
ave not installed 
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. D=
idn't 
realize that the aeroturbine had packing in it. If it performs as w=
ell as, or 
better than the hushpower, I may give it a shot. It's actually a bi=
t cheaper 
than the h.p. resonator.
>> 
>> Charlie
>> 
>>> On 1/17/2014 10:53 AM, Tracy wrote:
>>> The aero turbine sounded better than the Hushpower II&=
nbsp; but both change in 
tone over time, probably due to packing deteriorating.   S=
till, the AT was the 
best after they stabilized.
>>> 
>>> Tracy
>>> 
>>> Sent from my iPad
>>> 
>>>> On Jan 17, 2014, at 11:06, Charlie England <ceengland7@gmai=
l.com> wrote:
>>>> 
>>>> Time to order a muffler. My goal is to keep it ins=
ide the cowl (RV-7). I 
know, I know, but it looks better, and more important, it *sounds* b=
etter.
>>>> 
>>>> I believe that Dennis H. used this:
>>>> http://www.sum=
mitracing.com/parts/hsh-12412400/overview/=

>>>> I know it sounds great. Dennis, do you remember th=
e weight of just the 
resonator?
>>>> 
>>>> I know that Tracy is running an Aeroturbine (weight: 6 lbs o=
n the 20B in 
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 w=
ondering how the 
Aeroturbine will compare in performance (meaning: killing the harsh=
 harmonics of 
the rotary).
>>>> 
>>>> Tracy=
, you might be the only person who's heard both on a r=
otary. Based on 
your 20B experience, is it likely to work better than the Hushpower=
 Resonator on 
a Renesis? I'll be using a manifold/transition pipe similar to Denn=
is' setup to 
keep everything inside the cowl.
                          
>>>> 

                          
>>>> Thanks,

                          
>>>> 

                          
>>>> Charlie

                          
>>>> 

                          
>>>> 

                          
>>>> 

                          
>>>> --

                          
>>>> Homepage:  http://www.flyrotary.com/<=
o:p>

                          
>>>> Archive and UnSub:   http://mail.lancaironline.net:81/lists/flyrotary/List.html<=
/a>

                          
>>> --

                          
>>> 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/List.html=


                          
> --

                          
> Homepage:  http://www.flyrotary.com/<=
/span>

                          
> 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/List.html<=
/span>

 <= /o:p>


=20
= --Apple-Mail-3E35572A-B960-408A-BC48-11E8FBA5C2E6--