X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mail-ey0-f180.google.com ([209.85.215.180] verified) by logan.com (CommuniGate Pro SMTP 5.3.10) with ESMTP id 4600139 for flyrotary@lancaironline.net; Thu, 02 Dec 2010 14:01:19 -0500 Received-SPF: pass receiver=logan.com; client-ip=209.85.215.180; envelope-from=msteitle@gmail.com Received: by eyf18 with SMTP id 18so5524497eyf.25 for ; Thu, 02 Dec 2010 11:00:43 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:received:in-reply-to :references:date:message-id:subject:from:to:content-type; bh=4i9rEQlknHBMQtEAyrCcIzAw0H4kQg1mjP4YIsP+7po=; b=guk5fHZs2GcubY+ZBwKrbVVacZzkX1Acs5zPfjRmZHMwK1m8tl6tQ5XqRCGuEd9HGZ aADUf2LCpuBMG/ByQfKzJVSDbmwP+5mL64xGofxdzcoFC5ZvyL4DYZUTqMGMEAfyTcYf ojB8YDl88wlZVq65bzMaVUS8qFYfLrjkerrjI= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; b=WSB332+9DVKIeeXw5tO962bWvW1zmEx6csAt3vUtRNc8GTalloc/kEh8jylt3DDG5R oZAHinrVlB5HRQ5Ysx7Zsnp4o9Un2FOJJrD8hS8urqBWXuURALrB2jdNeGqNEJO+6Nlx 0j4eIqiZJ2/Qe2iHJYT8wGUMC/XhDL3K2ULZk= MIME-Version: 1.0 Received: by 10.213.31.209 with SMTP id z17mr1437201ebc.45.1291316443023; Thu, 02 Dec 2010 11:00:43 -0800 (PST) Received: by 10.213.34.212 with HTTP; Thu, 2 Dec 2010 11:00:42 -0800 (PST) In-Reply-To: References: Date: Thu, 2 Dec 2010 13:00:42 -0600 Message-ID: Subject: Re: [FlyRotary] Re: Reactive Muffler Design for PP was [FlyRotary] Re: Modified header Calculations From: Mark Steitle To: Rotary motors in aircraft Content-Type: multipart/alternative; boundary=0015174bf1e2e1309004967209ad --0015174bf1e2e1309004967209ad Content-Type: text/plain; charset=ISO-8859-1 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 future). 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 > 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 > *Sent:* Thursday, December 02, 2010 12:23 PM > *To:* Rotary motors in aircraft > *Subject:* [FlyRotary] Re: Reactive Muffler Design for PP was [FlyRotary] > Re: Modified header Calculations > > Ed, > > 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 >> *Sent:* Thursday, December 02, 2010 10:45 AM >> *To:* Rotary motors in aircraft >> *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: >> >> 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 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. >> >> Two things occurred - >> >> 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 >> >> >> >> > --0015174bf1e2e1309004967209ad Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable I looked at the Spin Tech site and those look to be a very robust design...= used by many serious racing types. =A0I may try one (some day in the futur= e). =A0

Mark

On Thu, D= ec 2, 2010 at 11:40 AM, Ed Anderson <eanderson@carolina.rr.com> wrote:=
All I can really tell you it combined the most so= und=20 deading with the least restriction of any of the muffler designs I tried - = which=20 really doesn't necessarily prove anything.=A0 I guess what you could do= is=20 calculate the open area of the disc and compare it to the area of the Exhau= st=20 port - if as large/larger in area then not necessarily a lot of restriction= to=20 gas flow.
=A0
SpinTech was the first reactive muffler Tracy=20 used.
=A0
Ed

Sent: Thursday, December 02, 2010 12:23 PM
To: Rotary motors in aircraft <= /div>
Subject: [FlyRotary] Re: Reactive Muffler Design for PP was=20 [FlyRotary] Re: Modified header Calculations
<= div>

Ed,=A0=20

It sounds like it might work, but also appears to be very restrictive.= =20 =A0Did you make any measurements regarding flow restriction? =A0Maybe a=20 larger diameter main body would alleviate the back pressure to an acceptabl= e=20 level, maybe not. =A0I would want to run some tests first.

I think we can pretty much rule out "absorptive" type muffle= rs for our=20 purposes. =A0Wasn't Tracy's early muffler a "reactive" ty= pe (Hushpower)?=20 =A0As 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>=20 wrote:
I agree, Finn.=A0 It probably would=A0 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.=A0 I always felt I was just one more step away from=20 making it successful - but did not take it.=A0 Just too leery of learning= =20 to weld with only one good eye ball left {:>)
=A0
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.=A0 The shaft/rod was= =20 not anchored otherwise.=A0 However, I did have a squished "Fishtail&= quot; end so=20 that the last disc could not back out of the tube.
=A0
Ed

Sent: Thursday, December 02, 2010 10:45 AM
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,
=A0
Since you have not gotten to the muffler part= of your=20 design, here are some thoughts (Yes, I did do 6 muffler experiments - d= on't=20 ask me why)
=A0
The one design=A0that was "almost" = totally=20 successful in achieving my goals is attached.=A0 Hard to make out the= =20 details, but enough to give you the general ideal.
=A0
My objective was trying to decided how to muf= fler the=20 shock wave (which creates most of the ear problems) but let the exhaust= gas=20 flow freely.=A0 My conclusion was that reactive design muffler was the= =20 only acceptable choice given our constraints.
=A0
What I came up with was the idea of stuffing = (I=A0=20 put five but I think three would make a considerable difference) disc w= ith=20 outer parts cut into blades and bent at a 45 deg angle into a tube.=A0= =20 Looked a bit like an old farm windmill.
=A0
=A0 The idea behind this approach was if you = looked=20 head on at the fan-disc - you see basically a solid metal front.=A0 Tha= t=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).=A0 The bent blades on the other hand would permit exhaust gas to= =20 flow with minimum restriction.
=A0
It really did deaden the sound where folks co= uld stand=20 by the wing tip with no problem hearing someone else talk.=A0I was=20 thrilled.=A0 It also met=A0 my minimum restriction as I could still=20 get my 6000 rpm static.
=A0
Ok, what went wrong - well, not being a welde= r I=20 resorted to other methods - which ultimately failed.=A0
=A0
=A0Two things occurred -
=A0
one if the disc broke loose of the small 5/8&= quot; thread=20 SS shaft from the Jam nuts on each side holding the disc, well, the dis= c=20 could (and did) begin to spin inside the tube like the turbine wheel of= a=20 jet engine.=A0This windmilling effect acted just like a windmilling pro= p=20 on the exhaust gas and definitely impeded gas flow.=A0 So can not permi= t=20 the disc to spin (the tips polished the inside of the tube where the=20 spun)
=A0
=A0Second because I donot weld, I did not sec= ure=20 the tips of the blades of the disc to the sides of the tube.=A0 Well th= e=20 shock wave naturally causes those blades to flex and eventually break= =20 off.
=A0
The SS disc were 2" in diam 1/8 thick=A0= and fit=20 really nice inside the 2 1/4" tubes.=A0 I cut slots in the outer p= art of=20 the SS=A0disc and then used pliers to bend the tabs to an approx 45 deg= =20 angle (see attached Jep).
=A0
So none of this was difficult to fabricate (t= edious=20 perhaps but not difficult).
=A0
I gave up on it because without welding skill= s I could=20 not figure out away to secure the tips of the blades to the tube to giv= e=20 them better support.=A0 Perhaps better than disc would have been cones= =20 but couldn't find any {:>).
=A0
So since I couldn't see any way around my= lack of=20 welding (and too cheap to hire someone), I went=A0 the hushpower II=20 route.
=A0
Just thought I would throw some fuel on your = fire=20 {:>)
=A0
FWIW
=A0
Ed





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