X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from poplet2.per.eftel.com ([203.24.100.45] verified) by logan.com (CommuniGate Pro SMTP 5.2.16) with ESMTP id 3876063 for flyrotary@lancaironline.net; Tue, 06 Oct 2009 03:45:49 -0400 Received-SPF: none receiver=logan.com; client-ip=203.24.100.45; envelope-from=lendich@aanet.com.au Received: from sv1-1.aanet.com.au (sv1-1.per.aanet.com.au [203.24.100.68]) by poplet2.per.eftel.com (Postfix) with ESMTP id C36B1173968 for ; Tue, 6 Oct 2009 15:44:57 +0800 (WST) Received: from ownerf1fc517b8 (203.171.92.134.static.rev.aanet.com.au [203.171.92.134]) by sv1-1.aanet.com.au (Postfix) with SMTP id 25FFFBEC02C for ; Tue, 6 Oct 2009 15:38:05 +0800 (WST) Message-ID: <719C9F751B1C4C1A9475E6A7269B6294@ownerf1fc517b8> From: "George Lendich" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: engine runup video Date: Tue, 6 Oct 2009 17:38:06 +1000 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_000A_01CA46AB.C37A3B00" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.5843 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.5579 X-Antivirus: avast! (VPS 091005-0, 10/05/2009), Outbound message X-Antivirus-Status: Clean This is a multi-part message in MIME format. ------=_NextPart_000_000A_01CA46AB.C37A3B00 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Mike, No worries, just thought that revisiting some of the basics might help = someone. On the reflective type mufflers the trick is to reflect the sound waves = ( which converts them to heat as they scrub the exhaust walls) - while = maintaining free exhaust passage. I don't know if Bill's and my design as well as we think it will, but it = does cover those criteria simply using cone shaped deflectors in the = area of exit of the exhaust. The trick is to not allow a 'direct line of = sight' for the sound waves to follow to the exit. We also cover heat issues by introducing cool air via the centre of the = exhaust and into the space between the exhaust and outer skin. The outer = skin also acting as a heat shield.=20 The process also incorporates exhaust augmentation from the centre cool = air when there is sufficient incoming air velocity and using the = velocity of the exhaust itself to draw cool air through the outer skin. Please remember this is not just my design but a collaborative attempt = with a well respected engineer. Mind you it's not super light either, = maybe using inconel but I haven't looked that that. I'm still working on my single before I can prove or disprove the design = - in the mean time I'm still building my shed. George ( down under) George, Thanks. Read through it yesterday. Nothing too earth shattering here. = What the article really didnt discuss and what I think is the major = problem we face in aircraft which is less of a problem in a car is the = need to get sufficient muffler volume. Finding space for a muffler that = actually has sufficient volume to do any good on an airplane is = problematic. Havent yet seen the muffler that relies on "reflective" (aka passive = cancellation) that really works. Tried a variety of them on various cars = over the years, and of course the homebrewed "spiral flow" muffler on my = airplane currently. Still waiting for someone to come up with one that = actually works and will fit on my airplane. Meanwhile I am intrigued by the absorptive design which I posted here = the other day. Its the only thing I've seen that actually provides = plenty of volume, appears to be capable of both muffling and lasting, = and wont look too terrible. I'm thinking about trying to throw together = something cheap and easy to try out before committing a bunch of time = and effort. Mike ----- Original Message -----=20 From: George Lendich=20 To: Rotary motors in aircraft=20 Sent: Sunday, October 04, 2009 11:38 PM Subject: [FlyRotary] Re: engine runup video Mike, The address is right, but it didn't work when I tried it also. What I did was use up to Miscellaneous on the address and clicked on = exhaust etc on the LHS of the screen - OK. George ( down under) ----- Original Message -----=20 From: Mike Wills=20 To: Rotary motors in aircraft=20 Sent: Monday, October 05, 2009 11:45 AM Subject: [FlyRotary] Re: engine runup video That link didnt work for me George. Mike ----- Original Message -----=20 From: George Lendich=20 To: Rotary motors in aircraft=20 Sent: Sunday, October 04, 2009 3:45 PM Subject: [FlyRotary] Re: engine runup video Mike, Here's a good site for general info on mufflers, mine and Bill = Jepson design is around deflection. www.nsxprime.com/FAQ/Miscellaneous/exhausttheory.html George ( down under) ----- Original Message -----=20 From: Mike Wills=20 To: Rotary motors in aircraft=20 Sent: Monday, October 05, 2009 2:34 AM Subject: [FlyRotary] engine runup video For anyone who hasnt had that first engine run and is looking = for some motivation. A buddy visited the hangar a few weeks ago and shot = some video of an engine runup. He posted it to his website and you can = find it here: http://www.stinsonvoyager.com/images/MikeWills13bEngineRun.wmv This was shot right after I re-installed my original muffler = after the aborted DNA muffler test. Noticeable in the video is the big = staging bog. I had this tuned out about 15 minutes after he shot the = video. Mike Wills RV-4 N144MW ------=_NextPart_000_000A_01CA46AB.C37A3B00 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
 Mike,
No worries, just thought that = revisiting some of=20 the basics might help someone.
On the reflective type mufflers = the trick is=20 to reflect the sound waves ( which converts them to heat as they scrub = the=20 exhaust walls) - while maintaining free exhaust passage.
 
I don't know if Bill's and my design as = well as we=20 think it will, but it does cover those criteria simply using cone shaped = deflectors in the area of exit of the exhaust. The trick is to not allow = a=20 'direct line of sight' for the sound waves to follow to the=20 exit.
 
We also cover heat issues by = introducing cool air=20 via the centre of the exhaust and into the space between the exhaust and = outer=20 skin. The outer skin also acting as a heat shield.
 
The process also incorporates = exhaust =20 augmentation from the centre cool air when there is = sufficient incoming air=20 velocity and using the velocity of the exhaust itself to draw cool air = through=20 the outer skin.
 
Please remember this is not just my = design but a=20 collaborative attempt with a well respected engineer. Mind you = it's=20 not super light either, maybe using inconel but I haven't looked that=20 that.
 
I'm still working on my single before I = can prove=20 or disprove the design - in the mean time I'm still building my=20 shed.
George ( down under)
George,
 
Thanks. Read through it yesterday. = Nothing too=20 earth shattering here. What the article really didnt discuss and = what I=20 think is the major problem we face in aircraft which is less of a = problem in a=20 car is the need to get sufficient muffler volume. Finding space for a = muffler=20 that actually has sufficient volume to do any good on an airplane = is=20 problematic.
 
Havent yet seen the muffler that = relies on=20 "reflective" (aka passive cancellation) that really works. Tried a = variety of=20 them on various cars over the years, and of course the homebrewed = "spiral=20 flow" muffler on my airplane currently. Still waiting for someone to = come up=20 with one that actually works and will fit on my airplane.
 
Meanwhile I am intrigued by the = absorptive design=20 which I posted here the other day. Its the only thing I've seen that = actually=20 provides plenty of volume, appears to be capable of both muffling and = lasting,=20 and wont look too terrible. I'm thinking about trying to throw = together=20 something cheap and easy to try out before committing a bunch of time = and=20 effort.
 
Mike
 
 
----- Original Message -----
From:=20 George=20 Lendich
To: Rotary motors in = aircraft=20
Sent: Sunday, October 04, = 2009 11:38=20 PM
Subject: [FlyRotary] Re: = engine runup=20 video

Mike,
The address is right, but it didn't = work when I=20 tried it also.
What I did was use up to = Miscellaneous on the=20 address and clicked on exhaust etc on the LHS of the screen -=20 OK.
George ( down under)
----- Original Message ----- =
From:=20 Mike = Wills=20
To: Rotary motors in = aircraft=20
Sent: Monday, October 05, = 2009 11:45=20 AM
Subject: [FlyRotary] Re: = engine runup=20 video

That link didnt work for me=20 George.
 
Mike
----- Original Message ----- =
From:=20 George=20 Lendich
To: Rotary motors in = aircraft=20
Sent: Sunday, October 04, = 2009 3:45=20 PM
Subject: [FlyRotary] Re: = engine=20 runup video

Mike,
Here's a good site for general = info on=20 mufflers, mine and Bill Jepson design is around = deflection.
www= .nsxprime.com/FAQ/Miscellaneous/exhausttheory.html
George ( down = under)
----- Original Message ----- =
From:=20 Mike=20 Wills
To: Rotary motors in=20 aircraft
Sent: Monday, October = 05, 2009=20 2:34 AM
Subject: [FlyRotary] = engine runup=20 video

For anyone who hasnt had that = first=20 engine run and is looking for some motivation. A buddy visited = the=20 hangar a few weeks ago and shot some video of an engine runup. = He=20 posted it to his website and you can find it = here:
 
h= ttp://www.stinsonvoyager.com/images/MikeWills13bEngineRun.wmv<= /DIV>
 
This was shot right after I = re-installed=20 my original muffler after the aborted DNA muffler test. = Noticeable in=20 the video is the big staging bog. I had this tuned out about = 15=20 minutes after he shot the video.
 
Mike Wills
RV-4=20 = N144MW
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