X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mail-ey0-f180.google.com ([209.85.215.180] verified) by logan.com (CommuniGate Pro SMTP 5.3.10) with ESMTP id 4586322 for flyrotary@lancaironline.net; Sat, 20 Nov 2010 10:54:12 -0500 Received-SPF: pass receiver=logan.com; client-ip=209.85.215.180; envelope-from=msteitle@gmail.com Received: by eyf18 with SMTP id 18so3492762eyf.25 for ; Sat, 20 Nov 2010 07:53:36 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:received:in-reply-to :references:date:message-id:subject:from:to:content-type; bh=tVpc9zE7hcrd7TZLIorehcOKVzGTmVL99cnEPRJLymE=; b=Lr1PjZULOATFbH1spyD5jm2c2EOHDTy5jto9CBMV3bx6goXjFHJwxgOR8xEKEB6eDD DiIGVOwQyWcBqPgdZnZPHGxtOJxdiyDktQjUBc/qdkecIc+2dYCySU58DNMOWqEkQIwD mn4sn3tN2LZi8rgyQ6L6ZCQy0Er61wr0zP1pw= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; b=qEpvA5Kqq+pjJN7bymAwQwASHkFlTiCNsQ+eys+X4hP/4MlhdIlU+pxjLozrmDrmug KClITkNmOk2En7M0SYklgTYjSgSfhwSgkLUkpaSfvDvrEVya0R4/uWE5zR66x40ebmSn V3tPdGvTFsJuzIpxs8YE6quYt8O+kfssGakaA= MIME-Version: 1.0 Received: by 10.213.8.67 with SMTP id g3mr2830948ebg.38.1290268415560; Sat, 20 Nov 2010 07:53:35 -0800 (PST) Received: by 10.213.36.17 with HTTP; Sat, 20 Nov 2010 07:53:35 -0800 (PST) In-Reply-To: References: Date: Sat, 20 Nov 2010 09:53:35 -0600 Message-ID: Subject: Re: [FlyRotary] Re: Tangential Muffler From: Mark Steitle To: Rotary motors in aircraft Content-Type: multipart/alternative; boundary=0015174c1982930d2004957e0630 --0015174c1982930d2004957e0630 Content-Type: text/plain; charset=ISO-8859-1 Ed, Can you run the numbers (length) for 1.8" ID tubing. I'm assuming the length would be a bit less to account for the larger diameter pipe. The reason I ask is that I can get 1 7/8" bends on Ebay pretty cheap. But that's the smallest size I find. Otherwise I'll be shopping at Burns $tainless. Mark On Sat, Nov 20, 2010 at 9:48 AM, Ed Anderson wrote: > 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 > *Sent:* Saturday, November 20, 2010 10:39 AM > *To:* Rotary motors in aircraft > *Subject:* [FlyRotary] Re: Tangential Muffler > > Ed, > > 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. > > One question. On your spreadsheet you define EVO = Exhaust Valve Closing. > Did you mean to say, EVO = Exhaust Valve Opening? > > 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. >> >> 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 >> >> >> 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 >> *Sent:* Saturday, November 20, 2010 6:32 AM >> *To:* Rotary motors in aircraft >> *Subject:* [FlyRotary] Tangential Muffler >> >> Guys, >> >> 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. >> >> 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. >> >> 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. >> >> 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. >> >> 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. >> >> Mark >> >> -- >> Homepage: http://www.flyrotary.com/ >> Archive and UnSub: >> http://mail.lancaironline.net:81/lists/flyrotary/List.html >> >> > --0015174c1982930d2004957e0630 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Ed,=A0

Can you run the numbers (length) for 1.8" ID= tubing. =A0I'm assuming the length would be a bit less to account for = the larger diameter pipe. =A0The reason I ask is that I can get 1 7/8"= bends on Ebay pretty cheap. =A0But that's the smallest size I find. = =A0Otherwise I'll be shopping at Burns $tainless. =A0

Mark

On Sat, Nov 20, = 2010 at 9:48 AM, Ed Anderson <eanderson@carolina.rr.com> wrote:
Welcome, Mark
=A0
As I said, the results seem reasonable to me - an= d yes,=20 you woke me up but had not had my 2nd cup of coffee {:>)..=A0 EVO should= =20 read Exhaust Valve Opening - my bad {:>)
=A0
Ed

Sent: Saturday, November 20, 2010 10:39 AM
To: Rotary motors in aircraft <= /div>
Subject: [FlyRotary] Re: Tangential Muffler

Ed,=A0=20

Thanks for waking up and posting that spreadsheet. =A0It looks like I= =20 need 1.5 ID pipes and 34.5" long pipes if I want max power at 6500. = =A0That=20 would be a nice sweet spot to shoot for. =A0

One question. =A0On your spreadsheet you define EVO =3D Exhaust Valve= =20 Closing. =A0Did you mean to say, EVO =3D Exhaust Valve Opening? =A0

Thanks,
Mark

On Sat, Nov 20, 2010 at 8:55 AM, Ed Anderson <eanderson@carolina.rr.com>=20 wrote:
Hi Mark,
=A0
From what I have read and heard,=A0a well=20 designed=A0exhaust system for a PP is more of a challenge than for any=20 other porting scheme.=A0 As Lynn has reported, the PP is even more effect= ed=20 by any back pressure in the exhaust system than our regular rotary=20 engines.
=A0
That said, I dug out a pretty good book on inta= kes and=20 exhausts (yes, they understand and address Finite Amplitude Waves in the= =20 exhaust system).=A0=A0=A0 Anyhow I thought I would extract what=20 appears to be some interesting insights for exhausts in general.=A0 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.
=A0
I put the calculations into a spreadsheet (atta= ched) and=20 the results do not seem unreasonable -=A0 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.=A0 Also I don't know your PP port timing - so th= e one=20 used is the factory Mazda PP Exhaust port closing from Paul Yaw's web= site -=20 73 Deg BBDC.
=A0
There appear to be two primary= power=20 enhancing benefits from a well designed exhaust system.
=A0
1.=A0 Minimum restriction to exhaust gas flow -= =20 apparently velocity is critical so diameter of pipes is important - appar= ently=20 optimum velocity is between Mach .45 and Mach .5 (got a Mach meter handy= =20 {:>))
=A0
2.=A0 Scavenging effect of the reflected exhaus= t FAW=20 to aid in pulling more mixture into the combustion chamber.
=A0
The well design system appear to maximize both= =20 attributes but generally for only a limited rpm range.
=A0
Engine displacement, RPM and intake/exhaust ove= r lap=20 appear to be the major engine factors in determining the desired exhaust= =20 parameters.
=A0
Ok, here are some extracted information - none = of it=20 necessarily new, but perhaps useful to review (even thought I know you kn= ow it=20 already)
=A0
Exhaust tuning works by using the proper header= pipe=20 length to time the arrival of the "suction" (expansion) wave re= flected back=20 from the end of the header to arrive at the engine exhaust port during th= e=20 overlap period - between Intake Value Opening and Exhaust Valve Closing.= =A0=20
=A0
If the scavenging wave is wide enough (time wis= e) and=20 the overlap (intake/exhaust) is short enough (probably not your case), th= e=20 exhaust system will remain in tune throughout a wide rpm range.
=A0
High out put, High speed engines with long over= laps=20 periods require much more precise tubing lengths to optimize power.=A0 As= =20 power levels increase, the margin for error decreases.
=A0
Collectors:=A0 (Length and Diameter - see sprea= dsheet=20 for some examples)
=A0
1.=A0 Longer collectors force the torque peak a= t=20 lower rpm=A0=A0because at higher rpm the reflected wave from the end of= =20 the longer collector does not get back in time to help scavenge the combu= stion=20 chamber and vice versa for short collectors.=A0 A "reverse funnel&qu= ot; 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.
=A0
2.=A0 The Amplitude of the reflected wave is=20 dependent on the difference in cross sectional area between the pipe and= =20 collector.=A0 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
=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0= =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0= =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0= =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0= =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0= =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0= =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0= =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0= =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0= =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0= =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0= =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0= =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=20
One interesting thing I read was the notion tha= t in some=20 cases, perhaps the headers should NOT be of equal length= -=20 IF you want a broader power range.=A0 The theory is that= =20 with slightly different lengths =A0the scavenging effect would be spread= =20 across a broader range and be less "peaky".=A0 I had never hear= =20 of=A0potential benefit of unequal headers before, but it would seem to ma= ke=20 sense if you want a less peaky power point.=A0 But, if you want the bigge= r=20 boost near one rpm range then equal length headers would appear=20 to=A0=A0apply
=A0
So there, that's what you get for waking me= =20 up.
=A0
Ed
=A0
Edward L. Anderson
Anderson Electronic Enter= prises=20 LLC
305 Reefton Road
Weddington, NC 28104
http://www.andersonee.com
http://www.eicommander.com

Sent: Saturday, November 20, 2010 6:32 AM
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. =A0Yes, another muffler experiment. =A0Seems I=20 can't get beyond the exhaust system. =A0=20

I did an experiment yesterday... with interesting results. =A0While = 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 perfor= mance=20 of my p-port 20b. =A0So, 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. =A0

First the bad news. =A0The 3-into-1 system is much louder, to the=20 point that it almost overwhelms my Zulu. =A0I haven't shattered any= =20 windows, but little children and small animals have been reported running= for=20 for their mothers. =A0FWIW, I'm running the stock exhaust splitters t= hat=20 came in the 20B housings.=A0

The positive news is that I picked up 10-12 mph on top speed! =A0So,= =20 it confirms my suspicions that the tangential muffler is too restrictive = for=20 my engine. =A0While definitely not optimal, the 3-into-1 design is clearl= y=20 better than the tangential muffler when it comes to making power. =A0=20 =A0=20

So, my plan is to build another exhaust from 625 inconel, making all= =20 three runners 31.5". =A0I haven't decided what I will use for a = muffler.=20 =A0I'll report back when I have more data. =A0

Mark

--
Homepage: =A0http://www.flyrotary.com/<= br>Archive and UnSub: =A0 http://mail.lancaironline.net:81/li= sts/flyrotary/List.html



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