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CBarber@BellairePolice.com

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=0AFrom: Rotary motors in aircraft on behalf of David Leonard
Sent: Sun 9/6/2009 3:39 PM
To: Rotary motors in aircraftSubject: [FlyRotary] Re: Muffling/ Morroso update

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Dont really NEED to. I flew quite a while wit= hout a muffler at all. But the turbo is not as good as a muffler an= d it is more enjoyable when quieter. The wife and dog particul= arly do better when it is quieter.

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-- David Leonard

Turbo Rotary RV-6 N4VY
http://N4VY.RotaryRoster.net
http://RotaryRoster.net

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On Sun, Sep 6, 2009 at 12:02 PM, Bill Bradburry <bbradburry@bells= outh.net> wrote:
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David,
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Do you need to muffle the turbo?
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Bill B
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From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of David Leonard
= Sent: Sunday, September 0= 6, 2009 2:47 PM
To: Ro= tary motors in aircraft
Subject:<= /SPAN> [FlyRotary] Re: Muffling/ Morroso update
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I have been running the Morro= so for the last 20 hours or so. Not sure it is the muffler, but I h= ave noticed a definate decrease in power. Too bad because it did a = nice job on the sound and only weighed 3 lbs.
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I think next I= will empty out the flowmaster shell and reinstall it - then live with th= e noise. Maybe put in some lava rocks if I get tired of the noise a= gain. Maybe try a fishmouth.
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<= FONT face=3D"Times New Roman" size=3D3>
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<= FONT face=3D"Times New Roman" size=3D3>--=
David Leonard

Turbo Rotary RV-6 N4VY
http://N4VY.RotaryRoster.net
= http://RotaryRoster.= net

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On Sun, Sep 6, 2009 a= t 10:19 AM, Lynn Hanover <lehanover@gmail.com> wrote:
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Mark/Ed/Bill,
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I was thinking along the same lines = as Bill - that the DNA is more restrictive resulting in richer mixtures a= t equivalent MAP. My home made muffler was a copy of the Moroso spiral fl= ow mufflers, but with a larger center tube. With my home made muffler I c= an look all the way through it so the DNA is clearly more restrictive. Wh= ich is why I'm surprised it didnt work better.
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The DNA sure= looks better than my home made muffler. Weld quality is great. Time will= tell how it holds up. The home made muffler was Inconel so I expect it w= ould be more durable in the long run.
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= The point of somethin= g else in the airflow path limiting HP is a good point. One of things I'v= e noticed is that I reach max power long before I reach max throttle. Sin= ce I'm making enough power for good performance I wasnt too worried about= this, but I am curious. Once I reach about 3/4 throttle I'm maxed out - = the last 1/4 doesnt do anything.
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Mike Wills
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RV-4 N144MW
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The first problem to overcom= e when muffling a rotary, is the supersonic shock wave leaving the engine= =2E If you can see through the muffler from end to end, it is probable th= at some part of that shock wave will exit the muffler. In order to slow t= he shock wave to subsonic it is required that the muffler provide some pr= essure in front of, Or, to impinge on the moving wave to slow it down.
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The center tube was perfed as was the front bulkhead. So = pressure from the front chamber could see the center tube cross section
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and the perfed bulkhead area. So in tha= t regard the muffler was ineffective if the front chaomber failed to drop= the shock wave to subsonic. However it did, and could hold the strongest= Rotary to 105 dB at 50 feet. (Full throttle at best power RPM) Probably = well above 9,000 RPM.
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So to muffle you drop the velocity, using vo= lume changes. By cooling the flow, by impinging on the flow with gasses c= ollected in the front of the muffler and reintroduced near the end of the= muffler, by using the flow to impinge on itself with splitters or divide= d flow tricks and reflectors. By absorbing the highest pressure peaks in = some form of replaceable media. By absorbing the most offensive frequenci= es in tuned cavities.
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Once the supersonic problem is delt with, co= nventional car mufflers are effective.
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My first muffler attempt sta= rted with the center tube being from a house jack strut. About 1/8 wall p= robably 1010 steel. Large diameter holes in the first 5 inches to help re= plicate the Mazda cavity muffler. Then a bulkhead with 1/4" holes. Then a= space of about 4" with no holes. Then thousands (it seemed like) of 1/8"= holes in the rest of the tube length. I worked pretty well and then melt= ed the center tube near the front. There was no media involved. &nbs= p;About 30" overall.
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&n= bsp;
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The rotary is slightly more tolorant of back p= ressure than is suspected, and this may be used to impinge<= /P>
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on fuffling flow. At the exhause flange, there is a= negative pressure well below ambient. A leak here draws cold air into th= e system and unburned fuel ignites with a popping sound, like a 2 cycle s= cooter off the power.
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&= nbsp;
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Perf tube mufflers take off the peaks and the= n impinge on the flow. So they may affect tuning every where, and then ch= ange as the media melts into little balls or is hammered to dust and leav= es the muffler.
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<= /P>
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It seemed to me that the Spintech was close to the = best for this application, and would like to have seen that run to destru= ction.
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Just my opinion, I could be completly wrong.<= /P>
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Lynn E. = Hanover
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