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 4600174 for flyrotary@lancaironline.net; Thu, 02 Dec 2010 14:22:09 -0500 Received-SPF: pass receiver=logan.com; client-ip=209.85.215.180; envelope-from=msteitle@gmail.com Received: by eyf18 with SMTP id 18so5549116eyf.25 for ; Thu, 02 Dec 2010 11:21:32 -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=ZXmSKEDKcAR43d5jBuhpybPf+Qg3JzNyYanzlIVaMaY=; b=q7Pzhzf6F5wj+IAPRfGW9t/2LzwEguND8e+Hdl+m9v0remiIBpsWapURYB47BfejpA uIDlFCAm5ZmtXpH8FOq+cBTHmGaESD0OYZ4tL2jofEH/cGnfOKBpqbZb8vEfNVn4EjM6 iRe7FAJDUDl7VBoljHoUwXD2aR8YKS1FSVxGQ= 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=ASJmFLepWUiL35xgm+8dFEgHNI3IejfnG6vrFzfqtjFdsC7tC8vdoa1d2cAIW+ihgN xOF6Gea6fVSQ0SuP0oO1qJEm9N80oIUHGukwR++iWRETs/336GJpBJE6RuBWEzr5d/5W hGfM6vJhr92kI9Kop3aC2GnkERMnC7F6cP4Dc= MIME-Version: 1.0 Received: by 10.213.9.140 with SMTP id l12mr6753818ebl.13.1291317692401; Thu, 02 Dec 2010 11:21:32 -0800 (PST) Received: by 10.213.34.212 with HTTP; Thu, 2 Dec 2010 11:21:32 -0800 (PST) In-Reply-To: References: Date: Thu, 2 Dec 2010 13:21:32 -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=0015174c3fa8590b9304967254df --0015174c3fa8590b9304967254df Content-Type: text/plain; charset=ISO-8859-1 Brian, That's very surprising to hear. Do you know which model he tried? They make a bunch of different types, some made specifically for racing applications. I find it hard to believe that their racing mufflers would "blow out like a cheap tire". (Maybe Tracy can enlighten us on this?) Mark On Thu, Dec 2, 2010 at 1:14 PM, wrote: > Tracy used one and it blew out like a cheap tire, IIRC. It's got sharp > corners, 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 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 >>> >>> >>> >>> >> > --0015174c3fa8590b9304967254df Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Brian,=A0

That's very surprising to hear. =A0Do you = know which model he tried? =A0They make a bunch of different types, some ma= de specifically for racing applications. =A0I find it hard to believe that = their racing mufflers would "blow out like a cheap tire". =A0(May= be Tracy can enlighten us on this?)

Mark =A0

On Thu, Dec = 2, 2010 at 1:14 PM, <bktrub@aol.com> wrote:
Tracy used one and it blew out like a cheap tire, IIRC. It's got s= harp corners, which don't hold up to heat and stress very well.
=A0
Brian Trubee
=A0


=A0


-----= 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 the Spin Tech site and those look to be a very robust desi= gn... used by many serious racing types. =A0I may try one (some day in the = future). =A0

Mark

On Thu, Dec 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 deading with the least restriction of any of the muffler designs I trie= d - which really doesn't necessarily prove anything.=A0 I guess what yo= u could do is calculate the open area of the disc and compare it to the are= a of the Exhaust port - if as large/larger in area then not necessarily a l= ot of restriction to gas flow.
=A0
SpinTech was the first reactive muffler Tracy use= d.
=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 [Fl= yRotary] Re: Modified header Calculations

Ed,=A0=20

It sounds like it might work, but also appears to be very restrictive.= =A0Did you make any measurements regarding flow restriction? =A0Maybe a la= rger diameter main body would alleviate the back pressure to an acceptable = 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 purposes. =A0Wasn't Tracy's early muffler a "reacti= ve" type (Hushpower)? =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> wrote:
I agree, Finn.=A0 It probably would=A0 not take m= uch, but I just got to the point I was tired of messing with it and put on = the HushPower II.=A0 I always felt I was just one more step away from makin= g it successful - but did not take it.=A0 Just too leery of learning to wel= d with only one good eye ball left {:>)
=A0
The 5/8" SS threaded shaft ran through the m= iddle of the tube/discs with a jam nut on each side of each disc.=A0 The sh= aft/rod was not anchored otherwise.=A0 However, I did have a squished "= ;Fishtail" end so 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 [Fl= yRotary] Re: Modified header Calculations

Hi Ed,

Not that I'm going to jump on this right away, but it seems that it wou= ld 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 ti= p.

But, how did you secure the 5/8" shaft 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 design, here are some thoughts (Yes, I did do 6 muffler experiments - = don't ask me why)
=A0
The one design=A0that was "almost" tota= lly successful in achieving my goals is attached.=A0 Hard to make out the d= etails, but enough to give you the general ideal.
=A0
My objective was trying to decided how to muffler= the shock wave (which creates most of the ear problems) but let the exhaus= t gas flow freely.=A0 My conclusion was that reactive design muffler was th= e only acceptable choice given our constraints.
=A0
What I came up with was the idea of stuffing (I= =A0 put five but I think three would make a considerable difference) disc w= ith outer parts cut into blades and bent at a 45 deg angle into a tube.=A0 = Looked a bit like an old farm windmill.
=A0
=A0 The idea behind this approach was if you look= ed head on at the fan-disc - you see basically a solid metal front.=A0 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).= =A0 The bent blades on the other hand would permit exhaust gas to flow with= minimum restriction.
=A0
It really did deaden the sound where folks could = stand by the wing tip with no problem hearing someone else talk.=A0I was th= rilled.=A0 It also met=A0 my minimum restriction as I could still get my 60= 00 rpm static.
=A0
Ok, what went wrong - well, not being a welder I = resorted to other methods - which ultimately failed.=A0
=A0
=A0Two things occurred -
=A0
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, th= e disc could (and did) begin to spin inside the tube like the turbine wheel= of a jet engine.=A0This windmilling effect acted just like a windmilling p= rop on the exhaust gas and definitely impeded gas flow.=A0 So can not permi= t the disc to spin (the tips polished the inside of the tube where the spun= )
=A0
=A0Second because I donot weld, I did not secure = the tips of the blades of the disc to the sides of the tube.=A0 Well the sh= ock wave naturally causes those blades to flex and eventually break off.
=A0
The SS disc were 2" in diam 1/8 thick=A0and = fit really nice inside the 2 1/4" tubes.=A0 I cut slots in the outer p= art of the SS=A0disc and then used pliers to bend the tabs to an approx 45 = deg angle (see attached Jep).
=A0
So none of this was difficult to fabricate (tedio= us perhaps but not difficult).
=A0
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 g= ive them better support.=A0 Perhaps better than disc would have been cones = but couldn't find any {:>).
=A0
So since I couldn't see any way around my lac= k of welding (and too cheap to hire someone), I went=A0 the hushpower II ro= ute.
=A0
Just thought I would throw some fuel on your fire= {:>)
=A0
FWIW
=A0
Ed






--0015174c3fa8590b9304967254df--