X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from cdptpa-omtalb.mail.rr.com ([75.180.132.122] verified) by logan.com (CommuniGate Pro SMTP 5.3.10) with ESMTP id 4586326 for flyrotary@lancaironline.net; Sat, 20 Nov 2010 10:49:54 -0500 Received-SPF: pass receiver=logan.com; client-ip=75.180.132.122; envelope-from=eanderson@carolina.rr.com Return-Path: X-Authority-Analysis: v=1.1 cv=Inhw+Jdt7z1D3BivGPfn2aw54OvUEJw5lAn/booRZkE= c=1 sm=0 a=PyNjkaOVL4wA:10 a=rPkcCx1H5rrOSfN0dPC7kw==:17 a=ayC55rCoAAAA:8 a=arxwEM4EAAAA:8 a=r1ClD_H3AAAA:8 a=7g1VtSJxAAAA:8 a=Ia-xEzejAAAA:8 a=mS2WzCJTMEyzqWJm_28A:9 a=Zg7tjK1BRpJVNgyVUZQA:7 a=4p_5WosNm3yyWxXrK49Up_YqnScA:4 a=wPNLvfGTeEIA:10 a=Qa1je4BO31QA:10 a=u5Wzkaagmzgqzfgh:21 a=I3qv1bqXHw27mzqC:21 a=pGLkceISAAAA:8 a=E93lBu2AAAAA:8 a=0EC_3TrS4JRqvEL4NFMA:9 a=cnExvwwJKqku2j9vFwkA:7 a=CbL0GyJgRUGCRTqjN_flpVhlGVEA:4 a=MSl-tDqOz04A:10 a=EzXvWhQp4_cA:10 a=hO30gm18fF0A:10 a=MpuOTR30KwMA:10 a=x6VBWS02HY8A:10 a=d1n8sfsg-lQA:10 a=NWVoK91CQyQA:10 a=rPkcCx1H5rrOSfN0dPC7kw==:117 X-Cloudmark-Score: 0 X-Originating-IP: 174.110.167.5 Received: from [174.110.167.5] ([174.110.167.5:62748] helo=EdPC) by cdptpa-oedge04.mail.rr.com (envelope-from ) (ecelerity 2.2.3.46 r()) with ESMTP id 3B/42-13137-DFDE7EC4; Sat, 20 Nov 2010 15:49:18 +0000 Message-ID: <0922C3BFBCF645BFA04452E23E04F1FF@EdPC> From: "Ed Anderson" To: "Rotary motors in aircraft" References: In-Reply-To: Subject: Re: [FlyRotary] Re: Tangential Muffler Date: Sat, 20 Nov 2010 10:48:58 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0068_01CB88A0.890CBF50" X-Priority: 3 X-MSMail-Priority: Normal Importance: Normal X-Mailer: Microsoft Windows Live Mail 14.0.8117.416 X-MimeOLE: Produced By Microsoft MimeOLE V14.0.8117.416 This is a multi-part message in MIME format. ------=_NextPart_000_0068_01CB88A0.890CBF50 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Welcome, Mark As I said, the results seem reasonable to me - and yes, you woke me up = but had not had my 2nd cup of coffee {:>).. EVO should read Exhaust = Valve Opening - my bad {:>) Ed From: Mark Steitle=20 Sent: Saturday, November 20, 2010 10:39 AM To: Rotary motors in aircraft=20 Subject: [FlyRotary] Re: Tangential Muffler Ed, =20 Thanks for waking up and posting that spreadsheet. It looks like I need = 1.5 ID pipes and 34.5" long pipes if I want max power at 6500. That = would be a nice sweet spot to shoot for. =20 One question. On your spreadsheet you define EVO =3D Exhaust Valve = Closing. Did you mean to say, EVO =3D Exhaust Valve Opening? =20 Thanks, Mark On Sat, Nov 20, 2010 at 8:55 AM, Ed Anderson = wrote: Hi Mark, From what I have read and heard, a well designed exhaust system for a = PP is more of a challenge than for any other porting scheme. As Lynn = has reported, the PP is even more effected by any back pressure in the = exhaust system than our regular rotary engines. That said, I dug out a pretty good book on intakes and exhausts (yes, = they understand and address Finite Amplitude Waves in the exhaust = system). Anyhow I thought I would extract what appears to be some = interesting insights for exhausts in general. There was formulas for = getting a rough estimate of header lengths and diameters - now these = were for piston engines but it would appear the dynamics of the pulse = turning would be the same for the rotary. I put the calculations into a spreadsheet (attached) and the results = do not seem unreasonable - one thing I don't know the effect of is the = generally higher exhaust temp of the rotary and what effect it might = have on the numbers. Also I don't know your PP port timing - so the one = used is the factory Mazda PP Exhaust port closing from Paul Yaw's web = site - 73 Deg BBDC. There appear to be two primary power enhancing benefits from a well = designed exhaust system. 1. Minimum restriction to exhaust gas flow - apparently velocity is = critical so diameter of pipes is important - apparently optimum velocity = is between Mach .45 and Mach .5 (got a Mach meter handy {:>)) 2. Scavenging effect of the reflected exhaust FAW to aid in pulling = more mixture into the combustion chamber. The well design system appear to maximize both attributes but = generally for only a limited rpm range. Engine displacement, RPM and intake/exhaust over lap appear to be the = major engine factors in determining the desired exhaust parameters. Ok, here are some extracted information - none of it necessarily new, = but perhaps useful to review (even thought I know you know it already) Exhaust tuning works by using the proper header pipe length to time = the arrival of the "suction" (expansion) wave reflected back from the = end of the header to arrive at the engine exhaust port during the = overlap period - between Intake Value Opening and Exhaust Valve Closing. = =20 If the scavenging wave is wide enough (time wise) and the overlap = (intake/exhaust) is short enough (probably not your case), the exhaust = system will remain in tune throughout a wide rpm range. High out put, High speed engines with long overlaps periods require = much more precise tubing lengths to optimize power. As power levels = increase, the margin for error decreases. Collectors: (Length and Diameter - see spreadsheet for some examples) 1. Longer collectors force the torque peak at lower rpm because at = higher rpm the reflected wave from the end of the longer collector does = not get back in time to help scavenge the combustion chamber and vice = versa for short collectors. A "reverse funnel" opening into the = collector appears to broaden the reflected wave and broadens the = effective rpm range - but reduces the amplitude of the wave. 2. The Amplitude of the reflected wave is dependent on the difference = in cross sectional area between the pipe and collector. A smaller dia = collector represents less area change and therefore reflects back a = lower amplitude wave and vice versa for a large diameter collector = = = = =20 One interesting thing I read was the notion that in some cases, = perhaps the headers should NOT be of equal length - IF you want a = broader power range. The theory is that with slightly different lengths = the scavenging effect would be spread across a broader range and be = less "peaky". I had never hear of potential benefit of unequal headers = before, but it would seem to make sense if you want a less peaky power = point. But, if you want the bigger boost near one rpm range then equal = length headers would appear to apply So there, that's what you get for waking me up. Ed Edward L. Anderson Anderson Electronic Enterprises LLC 305 Reefton Road Weddington, NC 28104 http://www.andersonee.com http://www.eicommander.com From: Mark Steitle=20 Sent: Saturday, November 20, 2010 6:32 AM To: Rotary motors in aircraft=20 Subject: [FlyRotary] Tangential Muffler Guys,=20 It has been way too quiet on the list lately, so I thought I would = post this report. Yes, another muffler experiment. Seems I can't get = beyond the exhaust system. =20 I did an experiment yesterday... with interesting results. While I am = very pleased with the muffling qualities of the tangential muffler, I = have been suspicious of it being responsible for the less-than-expected = performance of my p-port 20b. So, I removed the tangential muffler and = replaced it with the previous 3-into-1 exhaust w/DNA muffler that I had = been running for about 100 hrs. =20 First the bad news. The 3-into-1 system is much louder, to the point = that it almost overwhelms my Zulu. I haven't shattered any windows, but = little children and small animals have been reported running for for = their mothers. FWIW, I'm running the stock exhaust splitters that came = in the 20B housings.=20 The positive news is that I picked up 10-12 mph on top speed! So, it = confirms my suspicions that the tangential muffler is too restrictive = for my engine. While definitely not optimal, the 3-into-1 design is = clearly better than the tangential muffler when it comes to making = power. =20 So, my plan is to build another exhaust from 625 inconel, making all = three runners 31.5". I haven't decided what I will use for a muffler. = I'll report back when I have more data. =20 Mark -- Homepage: http://www.flyrotary.com/ Archive and UnSub: = http://mail.lancaironline.net:81/lists/flyrotary/List.html ------=_NextPart_000_0068_01CB88A0.890CBF50 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Welcome, Mark
 
As I said, the results seem reasonable to me - = and yes,=20 you woke me up but had not had my 2nd cup of coffee {:>)..  EVO = should=20 read Exhaust Valve Opening - my bad {:>)
 
Ed

Sent: Saturday, November 20, 2010 10:39 AM
Subject: [FlyRotary] Re: Tangential = Muffler

Ed, =20

Thanks for waking up and posting that spreadsheet.  It looks = like I=20 need 1.5 ID pipes and 34.5" long pipes if I want max power at 6500. =  That=20 would be a nice sweet spot to shoot for.  

One question.  On your spreadsheet you define EVO =3D Exhaust = Valve=20 Closing.  Did you mean to say, EVO =3D Exhaust Valve Opening? =  

Thanks,
Mark

On Sat, Nov 20, 2010 at 8:55 AM, Ed Anderson = <eanderson@carolina.rr.com&g= t;=20 wrote:
Hi Mark,
 
From what I have read and heard, a well=20 designed exhaust system for a PP is more of a challenge than for = any=20 other porting scheme.  As Lynn has reported, the PP is even more = effected=20 by any back pressure in the exhaust system than our regular rotary=20 engines.
 
That said, I dug out a pretty good book on = intakes and=20 exhausts (yes, they understand and address Finite Amplitude Waves in = the=20 exhaust system).    Anyhow I thought I would extract = what=20 appears to be some interesting insights for exhausts in general.  = There=20 was formulas for getting a rough estimate of header lengths and = diameters -=20 now these were for piston engines but it would appear the dynamics of = the=20 pulse turning would be the same for the rotary.
 
I put the calculations into a spreadsheet = (attached) and=20 the results do not seem unreasonable -  one thing I don't know = the effect=20 of is the generally higher exhaust temp of the rotary and what effect = it might=20 have on the numbers.  Also I don't know your PP port timing - so = the one=20 used is the factory Mazda PP Exhaust port closing from Paul Yaw's web = site -=20 73 Deg BBDC.
 
There appear to be two = primary power=20 enhancing benefits from a well designed exhaust system.
 
1.  Minimum restriction to exhaust gas = flow -=20 apparently velocity is critical so diameter of pipes is important - = apparently=20 optimum velocity is between Mach .45 and Mach .5 (got a Mach meter = handy=20 {:>))
 
2.  Scavenging effect of the reflected = exhaust FAW=20 to aid in pulling more mixture into the combustion = chamber.
 
The well design system appear to maximize both = attributes but generally for only a limited rpm range.
 
Engine displacement, RPM and intake/exhaust = over lap=20 appear to be the major engine factors in determining the desired = exhaust=20 parameters.
 
Ok, here are some extracted information - none = of it=20 necessarily new, but perhaps useful to review (even thought I know you = know it=20 already)
 
Exhaust tuning works by using the proper = header pipe=20 length to time the arrival of the "suction" (expansion) wave reflected = back=20 from the end of the header to arrive at the engine exhaust port during = the=20 overlap period - between Intake Value Opening and Exhaust Valve = Closing. =20
 
If the scavenging wave is wide enough (time = wise) and=20 the overlap (intake/exhaust) is short enough (probably not your case), = the=20 exhaust system will remain in tune throughout a wide rpm = range.
 
High out put, High speed engines with long = overlaps=20 periods require much more precise tubing lengths to optimize = power.  As=20 power levels increase, the margin for error decreases.
 
Collectors:  (Length and Diameter - see = spreadsheet=20 for some examples)
 
1.  Longer collectors force the torque = peak at=20 lower rpm  because at higher rpm the reflected wave from the = end of=20 the longer collector does not get back in time to help scavenge the = combustion=20 chamber and vice versa for short collectors.  A "reverse funnel" = opening=20 into the collector appears to broaden the reflected wave and broadens = the=20 effective rpm range - but reduces the amplitude of the = wave.
 
2.  The Amplitude of the reflected wave = is=20 dependent on the difference in cross sectional area between the pipe = and=20 collector.  A smaller dia collector represents less area change = and=20 therefore reflects back a lower amplitude wave and vice versa for a = large=20 diameter collector
          =             &= nbsp;           &n= bsp;           &nb= sp;           &nbs= p;            = ;            =             &= nbsp;           &n= bsp;           &nb= sp;           &nbs= p;            = ;            =             &= nbsp;           &n= bsp;           &nb= sp;           &nbs= p;            = ;            =             &= nbsp;           &n= bsp;           &nb= sp;           &nbs= p;            = ;            =      =20
One interesting thing I read was the notion = that in some=20 cases, perhaps the headers should NOT be of equal = length -=20 IF you want a broader power range.  The theory = is that=20 with slightly different lengths  the scavenging effect would be = spread=20 across a broader range and be less "peaky".  I had never hear=20 of potential benefit of unequal headers before, but it would seem = to make=20 sense if you want a less peaky power point.  But, if you want the = bigger=20 boost near one rpm range then equal length headers would appear=20 to  apply
 
So there, that's what you get for waking me=20 up.
 
Ed
 
Edward L. Anderson
Anderson Electronic = Enterprises=20 LLC
305 Reefton Road
Weddington, NC 28104
http://www.andersonee.com
http://www.eicommander.com

From: Mark Steitle =
Sent: Saturday, November 20, 2010 6:32 AM
To: Rotary = motors in=20 aircraft
Subject: [FlyRotary] Tangential Muffler

Guys,=20

It has been way too quiet on the list lately, so I = thought I=20 would post this report.  Yes, another muffler experiment. =  Seems I=20 can't get beyond the exhaust system.  =20

I did an experiment yesterday... with interesting results. =  While I=20 am very pleased with the muffling qualities of the tangential muffler, = I have=20 been suspicious of it being responsible for the less-than-expected = performance=20 of my p-port 20b.  So, I removed the tangential muffler and = replaced it=20 with the previous 3-into-1 exhaust w/DNA muffler that I had been = running for=20 about 100 hrs.  

First the bad news.  The 3-into-1 system is much louder, to = the=20 point that it almost overwhelms my Zulu.  I haven't shattered any = windows, but little children and small animals have been reported = running for=20 for their mothers.  FWIW, I'm running the stock exhaust splitters = that=20 came in the 20B housings. 

The positive news is that I picked up 10-12 mph on top speed! =  So,=20 it confirms my suspicions that the tangential muffler is too = restrictive for=20 my engine.  While definitely not optimal, the 3-into-1 design is = clearly=20 better than the tangential muffler when it comes to making power. =  =20  =20

So, my plan is to build another exhaust from 625 inconel, making = all=20 three runners 31.5".  I haven't decided what I will use for a = muffler.=20  I'll report back when I have more data.  

Mark

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


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