X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from imr-ma06.mx.aol.com ([64.12.78.142] verified) by logan.com (CommuniGate Pro SMTP 5.3.10) with ESMTP id 4600145 for flyrotary@lancaironline.net; Thu, 02 Dec 2010 14:15:23 -0500 Received-SPF: pass receiver=logan.com; client-ip=64.12.78.142; envelope-from=Bktrub@aol.com Received: from imo-ma04.mx.aol.com (imo-ma04.mx.aol.com [64.12.78.139]) by imr-ma06.mx.aol.com (8.14.1/8.14.1) with ESMTP id oB2JEjcl006426 for ; Thu, 2 Dec 2010 14:14:45 -0500 Received: from Bktrub@aol.com by imo-ma04.mx.aol.com (mail_out_v42.9.) id q.f6a.b2fdf7a (43890) for ; Thu, 2 Dec 2010 14:14:42 -0500 (EST) Received: from smtprly-da02.mx.aol.com (smtprly-da02.mx.aol.com [205.188.249.145]) by cia-dc05.mx.aol.com (v129.7) with ESMTP id MAILCIADC053-5bb34cf7f01cab; Thu, 02 Dec 2010 14:14:42 -0500 Received: from webmail-m007 (webmail-m007.sim.aol.com [64.12.101.90]) by smtprly-da02.mx.aol.com (v129.7) with ESMTP id MAILSMTPRLYDA022-5bb34cf7f01cab; Thu, 02 Dec 2010 14:14:36 -0500 References: To: flyrotary@lancaironline.net Subject: Re: [FlyRotary] Re: Reactive Muffler Design for PP was [FlyRotary] Re: Modified header Calculations Date: Thu, 02 Dec 2010 14:14:35 -0500 X-AOL-IP: 69.84.254.253 In-Reply-To: X-MB-Message-Source: WebUI MIME-Version: 1.0 From: bktrub@aol.com X-MB-Message-Type: User Content-Type: multipart/alternative; boundary="--------MB_8CD606C4AF482FA_724_2BE05_webmail-m007.sysops.aol.com" X-Mailer: AOL Webmail 32976-STANDARD Received: from 69.84.254.253 by webmail-m007.sysops.aol.com (64.12.101.90) with HTTP (WebMailUI); Thu, 02 Dec 2010 14:14:35 -0500 Message-Id: <8CD606C4AEFC038-724-116BD@webmail-m007.sysops.aol.com> X-Spam-Flag:NO X-AOL-SENDER: Bktrub@aol.com ----------MB_8CD606C4AF482FA_724_2BE05_webmail-m007.sysops.aol.com Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="us-ascii" Tracy used one and it blew out like a cheap tire, IIRC. It's got sharp cor= ners, which don't hold up to heat and stress very well. Brian Trubee -----Original Message----- From: Mark Steitle To: Rotary motors in aircraft Sent: Thu, Dec 2, 2010 11:00 am Subject: [FlyRotary] Re: Reactive Muffler Design for PP was [FlyRotary] Re= : Modified header Calculations I looked at the Spin Tech site and those look to be a very robust design..= . used by many serious racing types. I may try one (some day in the futur= e). =20 Mark On Thu, Dec 2, 2010 at 11:40 AM, Ed Anderson = wrote: All I can really tell you it combined the most sound deading with the leas= t restriction of any of the muffler designs I tried - which really doesn't= necessarily prove anything. I guess what you could do is calculate the= open area of the disc and compare it to the area of the Exhaust port - if= as large/larger in area then not necessarily a lot of restriction to gas= flow. =20 SpinTech was the first reactive muffler Tracy used. =20 Ed From: Mark Steitle=20 Sent: Thursday, December 02, 2010 12:23 PM To: Rotary motors in aircraft=20 Subject: [FlyRotary] Re: Reactive Muffler Design for PP was [FlyRotary] Re= : Modified header Calculations Ed, =20 It sounds like it might work, but also appears to be very restrictive. Di= d you make any measurements regarding flow restriction? Maybe a larger di= ameter main body would alleviate the back pressure to an acceptable level,= maybe not. I would want to run some tests first. What do you make of this site? http://en.wikibooks.org/wiki/Acoustics/Fil= ter_Design_and_Implementation I think we can pretty much rule out "absorptive" type mufflers for our pur= poses. Wasn't Tracy's early muffler a "reactive" type (Hushpower)? As I= recall it was heavy, but it worked very well. Mark On Thu, Dec 2, 2010 at 10:30 AM, Ed Anderson = wrote: I agree, Finn. It probably would not take much, but I just got to the po= int I was tired of messing with it and put on the HushPower II. I always= felt I was just one more step away from making it successful - but did no= t take it. Just too leery of learning to weld with only one good eye ball= left {:>) =20 The 5/8" SS threaded shaft ran through the middle of the tube/discs with= a jam nut on each side of each disc. The shaft/rod was not anchored othe= rwise. However, I did have a squished "Fishtail" end so that the last dis= c could not back out of the tube. =20 Ed From: Finn Lassen=20 Sent: Thursday, December 02, 2010 10:45 AM To: Rotary motors in aircraft=20 Subject: [FlyRotary] Re: Reactive Muffler Design for PP was [FlyRotary] Re= : Modified header Calculations Hi Ed, Not that I'm going to jump on this right away, but it seems that it would= be relatively easy to rosette weld the tips of the discs. Drill 1/8" (or= slightly bigger) holes through the tube at the center of each disc tip. But, how did you secure the 5/8" shaft itself? Finn On 12/1/2010 5:45 PM, Ed Anderson wrote:=20 Mark,=20 =20 Since you have not gotten to the muffler part of your design, here are som= e thoughts (Yes, I did do 6 muffler experiments - don't ask me why) =20 The one design that was "almost" totally successful in achieving my goals= is attached. Hard to make out the details, but enough to give you the ge= neral ideal. =20 My objective was trying to decided how to muffler the shock wave (which cr= eates most of the ear problems) but let the exhaust gas flow freely. My= conclusion was that reactive design muffler was the only acceptable choic= e given our constraints. =20 What I came up with was the idea of stuffing (I put five but I think thre= e would make a considerable difference) disc with outer parts cut into bla= des and bent at a 45 deg angle into a tube. Looked a bit like an old farm= windmill. =20 The idea behind this approach was if you looked head on at the fan-disc= - you see basically a solid metal front. That is what the shock wave wou= ld see and most (a lot?) of the energy would be reflected back toward the= engine (actually to the next disc in the tube). The bent blades on the= other hand would permit exhaust gas to flow with minimum restriction. =20 It really did deaden the sound where folks could stand by the wing tip wit= h no problem hearing someone else talk. I was thrilled. It also met my= minimum restriction as I could still get my 6000 rpm static. =20 Ok, what went wrong - well, not being a welder I resorted to other methods= - which ultimately failed.=20 =20 Two things occurred -=20 =20 one if the disc broke loose of the small 5/8" thread SS shaft from the Jam= nuts on each side holding the disc, well, the disc could (and did) begin= to spin inside the tube like the turbine wheel of a jet engine. This wind= milling effect acted just like a windmilling prop on the exhaust gas and= definitely impeded gas flow. So can not permit the disc to spin (the tip= s polished the inside of the tube where the spun) =20 Second because I donot weld, I did not secure the tips of the blades of= the disc to the sides of the tube. Well the shock wave naturally causes= those blades to flex and eventually break off. =20 The SS disc were 2" in diam 1/8 thick and fit really nice inside the 2 1/4= " tubes. I cut slots in the outer part of the SS disc and then used plier= s to bend the tabs to an approx 45 deg angle (see attached Jep). =20 So none of this was difficult to fabricate (tedious perhaps but not diffic= ult). =20 I gave up on it because without welding skills I could not figure out away= to secure the tips of the blades to the tube to give them better support.= Perhaps better than disc would have been cones but couldn't find any {:>= ). =20 So since I couldn't see any way around my lack of welding (and too cheap= to hire someone), I went the hushpower II route. =20 Just thought I would throw some fuel on your fire {:>) =20 FWIW =20 Ed ----------MB_8CD606C4AF482FA_724_2BE05_webmail-m007.sysops.aol.com Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset="us-ascii"
Tracy used one and it blew out like a cheap tire, IIRC. It's got shar= p corners, which don't hold up to heat and stress very well.
 
Brian Trubee
 


 


-----Original Message-----
From: Mark Steitle <msteitle@gmail.com>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Sent: Thu, Dec 2, 2010 11:00 am
Subject: [FlyRotary] Re: Reactive Muffler Design for PP was [FlyRotary] Re= : Modified header Calculations

I looked at th= e Spin Tech site and those look to be a very robust design... used by many= serious racing types.  I may try one (some day in the future).  = ;

Mark

On Thu, Dec 2, 2010 at 11:40 AM, Ed Anderson <eanderson@car= olina.rr.com> wrote:
All I can really tell you it combined the most sou= nd deading with the least restriction of any of the muffler designs I trie= d - which really doesn't necessarily prove anything.  I guess what yo= u could do is calculate the open area of the disc and compare it to the ar= ea of the Exhaust port - if as large/larger in area then not necessarily= a lot of restriction to gas flow.
 
SpinTech was the first reactive muffler Tracy used= .
 
Ed

Sent: Thursday, December 02, 2010 12:23 PM
Subject: [FlyRotary] Re: Reactive Muffler Design for PP was [F= lyRotary] Re: Modified header Calculations

Ed, =20

It sounds like it might work, but also appears to be very restrictive= .  Did you make any measurements regarding flow restriction?  Ma= ybe a larger diameter main body would alleviate the back pressure to an ac= ceptable level, maybe not.  I would want to run some tests first.

What do you make of this site?  http:/= /en.wikibooks.org/wiki/Acoustics/Filter_Design_and_Implementation
I think we can pretty much rule out "absorptive" type mufflers for ou= r purposes.  Wasn't Tracy's early muffler a "reactive" type (Hushpowe= r)?  As I recall it was heavy, but it worked very well.

Mark


On Thu, Dec 2, 2010 at 10:30 AM, Ed Anderson <eanderson@car= olina.rr.com> wrote:
I agree, Finn.  It probably would  not= take much, but I just got to the point I was tired of messing with it and= put on the HushPower II.  I always felt I was just one more step awa= y from making it successful - but did not take it.  Just too leery of= learning to weld with only one good eye ball left {:>)
 
The 5/8" SS threaded shaft ran through the middle= of the tube/discs with a jam nut on each side of each disc.  The sha= ft/rod was not anchored otherwise.  However, I did have a squished "F= ishtail" end so that the last disc could not back out of the tube.<= /div>
 
Ed

From: Finn Lassen=
Sent: Thursday, December 02, 2010 10:45 AM
Subject: [FlyRotary] Re: Reactive Muffler Design for PP was [F= lyRotary] Re: Modified header Calculations

Hi Ed,

Not that I'm going to jump on this right away, but it seems that it would= be relatively easy to rosette weld the tips of the discs. Drill 1/8" (or= slightly bigger) holes through the tube at the center of each disc tip.
But, how did you secure the 5/8" shaft itself?

Finn

On 12/1/2010 5:45 PM, Ed Anderson wrote:=20
Mark,
 
Since you have not gotten to the muffler part of= your design, here are some thoughts (Yes, I did do 6 muffler experiments= - don't ask me why)
 
The one design that was "almost" totally succ= essful in achieving my goals is attached.  Hard to make out the detai= ls, but enough to give you the general ideal.
 
My objective was trying to decided how to muffler= the shock wave (which creates most of the ear problems) but let the exhau= st gas flow freely.  My conclusion was that reactive design muffler= was the only acceptable choice given our constraints.
 
What I came up with was the idea of stuffing (I&nb= sp; put five but I think three would make a considerable difference) disc= with outer parts cut into blades and bent at a 45 deg angle into a tube.&= nbsp; Looked a bit like an old farm windmill.
 
  The idea behind this approach was if you lo= oked head on at the fan-disc - you see basically a solid metal front. = ; That is what the shock wave would see and most (a lot?) of the energy wo= uld be reflected back toward the engine (actually to the next disc in the= tube).  The bent blades on the other hand would permit exhaust gas= to flow with minimum restriction.
 
It really did deaden the sound where folks could= stand by the wing tip with no problem hearing someone else talk. I= was thrilled.  It also met  my minimum restriction as I could= still get my 6000 rpm static.
 
Ok, what went wrong - well, not being a welder I= resorted to other methods - which ultimately failed. 
 
 Two things occurred -
 
one if the disc broke loose of the small 5/8" thre= ad SS shaft from the Jam nuts on each side holding the disc, well, the dis= c could (and did) begin to spin inside the tube like the turbine wheel of= a jet engine. This windmilling effect acted just like a windmilling= prop on the exhaust gas and definitely impeded gas flow.  So can not= permit the disc to spin (the tips polished the inside of the tube where= the spun)
 
 Second because I donot weld, I did not secur= e the tips of the blades of the disc to the sides of the tube.  Well= the shock wave naturally causes those blades to flex and eventually break= off.
 
The SS disc were 2" in diam 1/8 thick and fit= really nice inside the 2 1/4" tubes.  I cut slots in the outer part= of the SS disc and then used pliers to bend the tabs to an approx 45= deg angle (see attached Jep).
 
So none of this was difficult to fabricate (tediou= s perhaps but not difficult).
 
I gave up on it because without welding skills I= could not figure out away to secure the tips of the blades to the tube to= give them better support.  Perhaps better than disc would have been= cones but couldn't find any {:>).
 
So since I couldn't see any way around my lack of= welding (and too cheap to hire someone), I went  the hushpower II ro= ute.
 
Just thought I would throw some fuel on your fire= {:>)
 
FWIW
 
Ed





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