X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from cdptpa-omtalb.mail.rr.com ([75.180.132.120] verified) by logan.com (CommuniGate Pro SMTP 5.3.10) with ESMTP id 4600053 for flyrotary@lancaironline.net; Thu, 02 Dec 2010 12:41:30 -0500 Received-SPF: pass receiver=logan.com; client-ip=75.180.132.120; envelope-from=eanderson@carolina.rr.com Return-Path: X-Authority-Analysis: v=1.1 cv=uESSSoDEku2quKX/oFXS2Smn5+55LTFcWFr5T5T8nFs= c=1 sm=0 a=zdKppqOtgB8A:10 a=rPkcCx1H5rrOSfN0dPC7kw==:17 a=xNgdfyqHAAAA:8 a=ayC55rCoAAAA:8 a=he5t_PREOnABH0UEeVUA:9 a=ipl9s-6yQh2nNKvj488A:7 a=bXpdCRJcRzDrx2P27e_gNdYkmkQA:4 a=wPNLvfGTeEIA:10 a=pGLkceISAAAA:8 a=Ia-xEzejAAAA:8 a=o1OHuDzbAAAA:8 a=RL8yzP_D_EeR64OcZ8gA:9 a=PKe_4GtVutrgjKdcgV4A:7 a=s0-NHG2IJqYqeHfHCvf4O-Fc1iMA:4 a=MSl-tDqOz04A:10 a=EzXvWhQp4_cA:10 a=ILCZio5HsAgA:10 a=rPkcCx1H5rrOSfN0dPC7kw==:117 X-Cloudmark-Score: 0 X-Originating-IP: 174.110.167.5 Received: from [174.110.167.5] ([174.110.167.5:50628] helo=EdPC) by cdptpa-oedge01.mail.rr.com (envelope-from ) (ecelerity 2.2.3.46 r()) with ESMTP id 7E/F1-07087-62AD7FC4; Thu, 02 Dec 2010 17:40:54 +0000 Message-ID: <20DD0CC359E9418BA09F63FBB28D658B@EdPC> From: "Ed Anderson" To: "Rotary motors in aircraft" References: In-Reply-To: Subject: Re: [FlyRotary] Re: Reactive Muffler Design for PP was [FlyRotary] Re: Modified header Calculations Date: Thu, 2 Dec 2010 12:40:41 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_000F_01CB921E.2174AD80" X-Priority: 3 X-MSMail-Priority: Normal Importance: Normal X-Mailer: Microsoft Windows Live Mail 14.0.8117.416 X-MimeOLE: Produced By Microsoft MimeOLE V14.0.8117.416 This is a multi-part message in MIME format. ------=_NextPart_000_000F_01CB921E.2174AD80 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable All I can really tell you it combined the most sound deading with the = least 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. SpinTech was the first reactive muffler Tracy used. 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. = Did you make any measurements regarding flow restriction? Maybe a = larger diameter 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/Filter_Design_and_Implementation I think we can pretty much rule out "absorptive" type mufflers for our = purposes. 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 point 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 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 shaft/rod was not = anchored otherwise. However, I did have a squished "Fishtail" end so = that the last disc could not back out of the tube. 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 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 successful in achieving my = goals is attached. Hard to make out the details, 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 exhaust 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 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. Looked a bit = like an old farm windmill. 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 would 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. 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.=20 Two things occurred -=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 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 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. 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 (tedious 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 route. Just thought I would throw some fuel on your fire {:>) FWIW Ed ------=_NextPart_000_000F_01CB921E.2174AD80 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
All I can really tell you it combined the most = sound=20 deading with the least restriction of any of the muffler designs I tried = - which=20 really doesn't necessarily prove anything.  I guess what you could = do is=20 calculate the open area of the disc and compare it to the area of the = Exhaust=20 port - if as large/larger in area then not necessarily a lot of = restriction to=20 gas flow.
 
SpinTech was the first reactive muffler Tracy=20 used.
 
Ed

Sent: Thursday, December 02, 2010 12:23 PM
Subject: [FlyRotary] Re: Reactive Muffler Design for PP was=20 [FlyRotary] Re: Modified header Calculations

Ed, =20

It sounds like it might work, but also appears to be very = restrictive.=20  Did you make any measurements regarding flow restriction? =  Maybe a=20 larger diameter main body would alleviate the back pressure to an = acceptable=20 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_Implemen= tation
I think we can pretty much rule out "absorptive" type mufflers for = our=20 purposes.  Wasn't Tracy's early muffler a "reactive" type = (Hushpower)?=20  As I recall it was heavy, but it worked very well.

Mark


On Thu, Dec 2, 2010 at 10:30 AM, Ed Anderson = <eanderson@carolina.rr.com&g= t;=20 wrote:
I agree, Finn.  It probably would  = not take=20 much, but I just got to the point I was tired of messing with it and = put on=20 the HushPower II.  I always felt I was just one more step away = from=20 making it successful - but did not take it.  Just too leery of = learning=20 to weld with only one good eye ball left {:>)
 
The 5/8" SS threaded shaft ran through the = middle of the=20 tube/discs with a jam nut on each side of each disc.  The = shaft/rod was=20 not anchored otherwise.  However, I did have a squished = "Fishtail" end so=20 that the last disc could not back out of the tube.
 
Ed

From: Finn = Lassen
Sent: Thursday, December 02, 2010 10:45 AM
To: Rotary = motors in=20 aircraft
Subject: [FlyRotary] Re: Reactive Muffler Design for PP = was=20 [FlyRotary] Re: Modified header Calculations

Hi Ed,

Not that I'm going to jump on this right = away,=20 but it seems that it would be relatively easy to rosette weld the tips = of the=20 discs. Drill 1/8" (or slightly bigger) holes through the tube at the = center of=20 each disc tip.

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