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 3881919 for flyrotary@lancaironline.net; Sat, 10 Oct 2009 17:15:41 -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 D9ED8173711 for ; Sun, 11 Oct 2009 05:15:04 +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 C541ABEC009 for ; Sun, 11 Oct 2009 05:15:02 +0800 (WST) Message-ID: <7F9FF0069F154241A6C479E79249CCCE@ownerf1fc517b8> From: "George Lendich" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Your muffler Date: Sun, 11 Oct 2009 07:15:06 +1000 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0009_01CA4A42.8EFB6EE0" 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_0009_01CA4A42.8EFB6EE0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Interesting Mike, The exhaust seems to be made up of a fairly large expansion chamber = followed by a perforated (Piccolo)tube, my guess is that the chaps who = are refurbishing the aircraft would know what if anything is in it. I = would assume that there's nothing in the expansion chamber and a = restrictor in the perforated tube to force the exhaust out of the = perforations. The whole lot being cooled by the cool air inlet. Simple but effective, like the reduction gear box. Interestingly it = was developed from glider plans. I never saw one in Vietnam but I was there a bit earlier than 70/71.=20 We were winning when I was there. George ( down under) George, I agree with you on getting the muffler out of the cowl. But I = know there are those that would like to keep it under cowl, and of = course the canard guys probably dont have a choice. For a canard this = could be a good way to go. There's a youtube video from a guy restoring a YO-3A up in the LA = area. It's pretty dry but a minute in there is a shot of the exhaust = system unfaired. I'd like to know what if anything is in that muffler at = the front. Behind that muffler is what the guy refers to as a "piccolo = tube" which is also enclosed in the fairing. The fairing and the = fuselage side are lined with absorbant material held in place with a = metal screen. http://www.youtube.com/watch?v=3DrIhK8PWRMbI Mike Wills RV-4 N144MW ----- Original Message -----=20 From: George Lendich=20 To: Rotary motors in aircraft=20 Sent: Friday, October 09, 2009 2:12 PM Subject: [FlyRotary] Re: Your muffler 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_0009_01CA4A42.8EFB6EE0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
 
Interesting Mike,
 
The exhaust seems to be made up of a = fairly=20 large expansion chamber followed by a = perforated (Piccolo)tube, my=20 guess is that the chaps who are refurbishing the aircraft would know = what if=20 anything is in it. I would assume that there's nothing in the = expansion=20 chamber and a restrictor in the perforated tube to force the exhaust = out of=20 the perforations.  The whole lot being cooled by the cool air=20 inlet.
Simple but effective, like the = reduction gear=20 box. Interestingly it was developed from glider plans.
I never saw one in Vietnam but I was = there a bit=20 earlier than 70/71.
We were winning when I was = there.
George ( down under)
 
George, I agree with you on getting = the muffler=20 out of the cowl. But I know there are those that would like to keep it = under=20 cowl, and of course the canard guys probably dont have a choice. For a = canard=20 this could be a good way to go.
 
There's a youtube video from a guy = restoring a=20 YO-3A up in the LA area. It's pretty dry but a minute in there is a = shot of=20 the exhaust system unfaired. I'd like to know what if anything is in = that=20 muffler at the front. Behind that muffler is what the guy refers to as = a=20 "piccolo tube" which is also enclosed in the fairing. The fairing and = the=20 fuselage side are lined with absorbant material held in place with a = metal=20 screen.
 
http://www.youtube.= com/watch?v=3DrIhK8PWRMbI
 
Mike Wills
RV-4 N144MW
----- Original Message -----
From:=20 George=20 Lendich
To: Rotary motors in = aircraft=20
Sent: Friday, October 09, = 2009 2:12=20 PM
Subject: [FlyRotary] Re: Your = muffler

 
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=20 sitting within a half circle recess formed in the cowl, but there = no=20 reason that it can't sit behind the cowl under the fuselage.
 
If your talking about the long = under=20 fuselage design which forms part of the fuselage, I must admit I = like that=20 design as well. The longer the better in my opinion, you could = string a=20 number of light weight mufflers along a line, each feeing into the = next=20 with cooling air mixing in,  as well as cooling the OD. That = would be=20 super quiet. I notice the best muffling ( to date) is done with = more than=20 one muffler i.e. a primary and a secondary.
 
I'm not trying to convince anyone = this is=20 the best design, merely putting it up for possible solution to the = problem.  As you and others have = said, off-the-shelf types=20 aren't lasting anywhere near long enough. Bill Jepson and I = laboured over=20 this design for some time, before we came to the final design, I = have been=20 unable to finish my single so haven't been able to test it yet - = but it=20 sure looks good.
 
George ( down under)
 
OK George, my memory is now = jogged having=20 seen your drawing. I liked the design when I saw it the first time = but=20 discounted it for my application because I couldnt see a good = way to=20 make any muffler with a tangential entry fit my airframe. This is = the same=20 reason I 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=20 has in common with the YO-3A muffler I've been talking about. I = believe=20 the YO-3A design would prove superior by virtue of the greatly = increased=20 volume of the muffler and the use of absorptive = materials.
 
Of course until someone builds = one and tries=20 it who knows if it will hold up to the abusive exhaust output of a = rotary.=20 But the YO-3A design does have the advantage of being flight = proven in a=20 pretty tough environment - low altitude recon in=20 Vietnam.
 
Your muffler design (or Al's) = is a=20 winner if the goal is to keep the muffler within the confines of = the cowl.=20 My cowl is 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=20 9:18 PM
Subject: [FlyRotary] Re: = Your=20 muffler

Al,
Not tested yet, but have one = almost=20 complete 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=20 waves will be going all over the place within the exhaust and I = tried to=20 replicate that with the zig zaggy lines.
 
There is no restriction as the = area around=20 the 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,=20 whereas sound waves travel in a straight line ( I=20 think).  Bill did have = me put in a=20 reflector plate opposite the incoming exhaust, but I don't know = if this=20 will interrupt the swirl motion, I suspect it might. The = reflector plate=20 is on the LHS of the parts count - photo = attached.
 
George ( down = under)

George;

 

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

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

 

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

 

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

 

Al=20 G

 

-----Original=20 Message-----
From:=20 Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] = On Behalf Of = George=20 Lendich
Sent:=20 Thursday, 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)

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

From:=20 Kelly=20 Troyer

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

Subject:=20 [FlyRotary] Your muffler

 

 =20 George,

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

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

 

 

Thanks,

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


 

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


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

--
Homepage:  = http://www.flyrotary.com/
Archive and=20 UnSub:  =20 = http://mail.lancaironline.net:81/lists/flyrotary/List.html
------=_NextPart_000_0009_01CA4A42.8EFB6EE0--