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 3880919 for flyrotary@lancaironline.net; Fri, 09 Oct 2009 17:13:25 -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 5E8171737F5 for ; Sat, 10 Oct 2009 05:12:49 +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 3E4CEBEC001 for ; Sat, 10 Oct 2009 05:12:47 +0800 (WST) Message-ID: <90DBA17B8CF54E43A5D15FBFE3E3CFAC@ownerf1fc517b8> From: "George Lendich" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Your muffler Date: Sat, 10 Oct 2009 07:12:49 +1000 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_000E_01CA4979.135B9540" 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 091009-0, 10/09/2009), Outbound message X-Antivirus-Status: Clean This is a multi-part message in MIME format. ------=_NextPart_000_000E_01CA4979.135B9540 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Thanks Mike, For your kind comments, but I must emphasize that this design is = designed primarily for outside cowl use. I understand that this, to some = people, might give rise to concerns of extra drag - but to my mind = anything to get the heat out of the cowl. For my own design I envisage the muffler sitting within a half circle = recess formed in the cowl, but there no reason that it can't sit behind = the cowl under the fuselage. If your talking about the long under fuselage design which forms part = of the fuselage, I must admit I like that design as well. The longer the = better in my opinion, you could string a number of light weight mufflers = along a line, each feeing into the next with cooling air mixing in, as = well as cooling the OD. That would be super quiet. I notice the best = muffling ( to date) is done with more than one muffler i.e. a primary = and a secondary. I'm not trying to convince anyone this is the best design, merely = putting it up for possible solution to the problem. As you and others = have said, off-the-shelf types aren't lasting anywhere near long enough. = Bill Jepson and I laboured over this design for some time, before we = came to the final design, I have been unable to finish my single so = haven't been able to test it yet - but it sure looks good. George ( down under) OK George, my memory is now jogged having seen your drawing. I liked = the design when I saw it the first time but discounted it for my = application because I couldnt see a good way to make any muffler with a = tangential entry fit my airframe. This is the same reason I passed on = Al's proven muffler design. I think the use of cooling airflow introduced into the muffler makes a = lot of sense and this is something your design has in common with the = YO-3A muffler I've been talking about. I believe the YO-3A design would = prove superior by virtue of the greatly increased volume of the muffler = and the use of absorptive materials. Of course until someone builds one and tries it who knows if it will = hold up to the abusive exhaust output of a rotary. But the YO-3A design = does have the advantage of being flight proven in a pretty tough = environment - low altitude recon in Vietnam. Your muffler design (or Al's) is a winner if the goal is to keep the = muffler within the confines of the cowl. My cowl is already too tight = without a muffler in it. Mike Wills RV-4 N144MW=20 ----- Original Message -----=20 From: George Lendich=20 To: Rotary motors in aircraft=20 Sent: Thursday, October 08, 2009 9:18 PM Subject: [FlyRotary] Re: Your muffler Al, Not tested yet, but have one almost complete for the single. The cones are there to stop the sound waves having a direct line of = sight out the rear end, the sound waves will be going all over the place = within the exhaust and I tried to replicate that with the zig zaggy = lines. There is no restriction as the area around the back to back cones, = is equal to the area of the 2" exhaust manifold area. However I do take your point on swirl restriction, but I don't see a = problem as it will swirl out the end, whereas sound waves travel in a = straight line ( I think). Bill did have me put in a reflector plate = opposite the incoming exhaust, but I don't know if this will interrupt = the swirl motion, I suspect it might. The reflector plate is on the LHS = of the parts count - photo attached. George ( down under) George; Nice design. Has anyone run one of these yet. My concern with the tangential muffler is something called 'swirl = flow choking' - discovered in connection with a similar attempt with gas = turbine exhaust. High circumferential velocity tends to keep the flow = from moving out the end, and consequent pressure buildup. I don't know = whether it applies to the pulsed flow, but it might, and your conical = restriction toward the outlet could make it worse.=20 To avoid that possibility in my tangential muffler I added = internal vanes at a 45 degree angle opposite the ports, and extended the = header pipes into muffler to a squared end. Disrupts the circumferential = flow and helps direct the exhaust toward the exit. Your depiction of the idealized sounds waves going axially; ah-h, = well; maybe/maybe notJ. Al G -----Original Message----- From: Rotary motors in aircraft = [mailto:flyrotary@lancaironline.net] On Behalf Of George Lendich Sent: Thursday, October 08, 2009 1:14 PM To: Rotary motors in aircraft Subject: [FlyRotary] Re: Your muffler Kelly There you go matey. All off the shelf SS cones and tube. George ( down under) ----- Original Message -----=20 From: Kelly Troyer=20 To: Rotary motors in aircraft=20 Sent: Thursday, October 08, 2009 9:32 PM Subject: [FlyRotary] Your muffler George, Do you have a photo or drawing available of your muffler = design..........I seem to remember seeing some design info in the past but do not know = where to find it...... Thanks, -- Kelly Troyer=20 "Dyke Delta"_13B ROTARY Engine=20 "RWS"_RD1C/EC2/EM2=20 "Mistral"_Backplate/Oil Manifold=20 =20 -------------- Original message from "George Lendich" = : --------------=20 > Ed,=20 > Cones are the GO.=20 >=20 > Any bare edge will take a battering from the heat and shock = waves. Cones=20 > formed back to back eliminate any edges.=20 >=20 > There must be supporting structure for the cones, I've used = 1/4" solid=20 > round bar welded into the exhaust skin.=20 > George (down under)=20 -------------------------------------------------------------------------= --- -- Homepage: http://www.flyrotary.com/ Archive and UnSub: = http://mail.lancaironline.net:81/lists/flyrotary/List.html ------=_NextPart_000_000E_01CA4979.135B9540 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
 
Thanks Mike,
For your kind comments, but I must = emphasize=20 that this design is  designed primarily for outside cowl use. I=20 understand that this, to some people, might give rise to concerns of = extra=20 drag - but to my mind anything to get the heat out of the cowl.
 
For my own design I envisage the = muffler sitting=20 within a half circle recess formed in the cowl, but there no reason = that it=20 can't sit behind the cowl under the fuselage.
 
If your talking about the long under = fuselage=20 design which forms part of the fuselage, I must admit I like that = design as=20 well. The longer the better in my opinion, you could string a number = of light=20 weight mufflers along a line, each feeing into the next with cooling = air=20 mixing in,  as well as cooling the OD. That would be super quiet. = I=20 notice the best muffling ( to date) is done with more than one muffler = i.e. a=20 primary and a secondary.
 
I'm not trying to convince anyone this = is the=20 best design, merely putting it up for possible solution to the = problem. =20 As you and others have said, off-the-shelf types aren't = lasting=20 anywhere near long enough. Bill Jepson and I laboured over this design = for=20 some time, before we came to the final design, I have been unable to = finish my=20 single so haven't been able to test it yet - but it sure looks = good.
 
George ( down under)
 
OK George, my memory is now jogged = having seen=20 your drawing. I liked the design when I saw it the first time but = discounted=20 it for my application because I couldnt see a good way to make = any=20 muffler with a tangential entry fit my airframe. This is the same = reason I=20 passed on Al's proven muffler design.
 
I think the use of cooling airflow = introduced=20 into the muffler makes a lot of sense and this is something your = design has in=20 common with the YO-3A muffler I've been talking about. I believe the = YO-3A=20 design would prove superior by virtue of the greatly increased volume = of the=20 muffler and the use of absorptive materials.
 
Of course until someone builds one = and tries it=20 who knows if it will hold up to the abusive exhaust output of a = rotary. But=20 the YO-3A design does have the advantage of being flight proven in a = pretty=20 tough environment - low altitude recon in Vietnam.
 
Your muffler design (or Al's) = is a winner if=20 the goal is to keep the muffler within the confines of the cowl. My = cowl is=20 already too tight without a muffler in it.
 
Mike Wills
RV-4 N144MW 
----- Original Message -----
From:=20 George=20 Lendich
To: Rotary motors in = aircraft=20
Sent: Thursday, October 08, = 2009 9:18=20 PM
Subject: [FlyRotary] Re: Your = muffler

Al,
Not tested yet, but have one almost = complete=20 for the single.
 
The cones are there to stop the = sound=20 waves having a direct line of sight out the rear end, the sound = waves=20 will be going all over the place within the exhaust and I tried to = replicate=20 that with the zig zaggy lines.
 
There is no restriction as the area = around the=20 back to back cones, is equal to the area of the 2" exhaust=20 manifold area.
 
However I do take your point on = swirl=20 restriction, but I don't see a problem as it will swirl out the end, = whereas=20 sound waves travel in a straight line ( I think).  Bill did have me put in a reflector plate = opposite the=20 incoming exhaust, but I don't know if this will interrupt the swirl = motion,=20 I suspect it might. The reflector plate is on the LHS of the parts = count=20 - photo attached.
 
George ( down under)

George;

 

Nice=20 design.  Has anyone run one of these yet.

My = concern with=20 the tangential muffler is something called =91swirl flow = choking=92 =96=20 discovered in connection with a similar attempt with gas turbine = exhaust.=20  High circumferential velocity tends to keep the flow from = moving out=20 the end, and consequent pressure buildup.  I don=92t know = whether it=20 applies to the pulsed flow, but it might, and your conical = restriction=20 toward the outlet could make it worse.

 

To = avoid that=20 possibility in my tangential muffler I added internal vanes at a = 45 degree=20 angle opposite the ports, and extended the header pipes into = muffler to a=20 squared end. Disrupts the circumferential flow and helps direct = the=20 exhaust toward the exit.

 

Your = depiction=20 of the idealized sounds waves going axially; ah-h, well; = maybe/maybe=20 notJ.

 

Al=20 G

 

-----Original=20 Message-----
From: Rotary=20 motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of George=20 Lendich
Sent: = Thursday,=20 October 08, 2009 1:14 PM
To: Rotary motors in=20 aircraft
Subject:=20 [FlyRotary] Re: Your muffler

 

Kelly

There = you go=20 matey. All off the shelf SS cones and = tube.

George ( down=20 under)

----- Original=20 Message -----

From: Kelly = Troyer=20

To: Rotary motors in = aircraft=20

Sent:=20 Thursday, October 08, 2009 9:32 PM

Subject:=20 [FlyRotary] Your muffler

 

 =20 George,

  =20 Do you have a photo or drawing available of your muffler=20 design..........I seem to

remember=20 seeing some design info in the past but do not know where to = find=20 it......

 

 

Thanks,

--
Kelly=20 Troyer
"Dyke Delta"_13B ROTARY Engine
"RWS"_RD1C/EC2/EM2 =
"Mistral"_Backplate/Oil Manifold=20


 

-------------- Original message from = "George=20 Lendich" <lendich@aanet.com.au>: -------------- =


>=20 Ed,
> Cones are the GO.
>
> Any bare edge = will=20 take a battering from the heat and shock waves. Cones
> = formed=20 back to back eliminate any edges.
>
> There must = be=20 supporting structure for the cones, I've used 1/4" solid =
>=20 round bar welded into the exhaust skin.
> George (down = under)=20 =

--
Homepage:  http://www.flyrotary.com/
Archive = and=20 UnSub:  =20 = http://mail.lancaironline.net:81/lists/flyrotary/List.html
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