X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from fmailhost02.isp.att.net ([207.115.11.52] verified) by logan.com (CommuniGate Pro SMTP 5.3.10) with ESMTP id 4586764 for flyrotary@lancaironline.net; Sat, 20 Nov 2010 22:55:23 -0500 Received-SPF: none receiver=logan.com; client-ip=207.115.11.52; envelope-from=bbradburry@bellsouth.net Received: from desktop (adsl-85-148-241.mco.bellsouth.net[98.85.148.241]) by isp.att.net (frfwmhc02) with SMTP id <20101121035446H020024idje>; Sun, 21 Nov 2010 03:54:46 +0000 X-Originating-IP: [98.85.148.241] From: "Bill Bradburry" To: "'Rotary motors in aircraft'" References: In-Reply-To: Subject: RE: [FlyRotary] Re: Exhaust Calcuations Date: Sat, 20 Nov 2010 22:54:46 -0500 Message-ID: <5A9CE3983E644067844FB1F6FA997A1A@Desktop> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0003_01CB8905.EE0248C0" X-Mailer: Microsoft Office Outlook 11 Thread-Index: AcuJJ2WCqVP77o6+SyaZi+7qUs7IZQABERVA X-MimeOLE: Produced By Microsoft MimeOLE V6.0.6001.18049 This is a multi-part message in MIME format. ------=_NextPart_000_0003_01CB8905.EE0248C0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit It seems that at 6000 rpm, the rotor would be doing 2000. that is 720,000 degrees of rotation per min or 12,000 per second. So if the exhaust port is 12 degrees of rotation wide, it would require .001 seconds to open fully, followed by 50 more degrees of rotation to squish the face to its lowest volume, that is another 4 ms, (a total of 5 ms) then as the volume is increased, there will be another 60 degrees or 5 ms before the next apex seal blows by and starts it all over again. On a graph, it should look like a tremendous spike followed by a positive then a negative sine wave. The whole thing would be 10 ms. (After thinking about it, maybe it would be 9 ms with half of the spike on both ends??) The spike would occur while both faces are open to the port so the last portion of the negative sine wave would overlap this spike. I am having trouble getting my head around what is actually happening. Then to try and figure out what would help scavenge, and then figure out how to do that, and then figure out how to build an exhaust that will do it. I am getting a headache and going to bed! :>) Good Luck with this project! Bill B _____ From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Mark Steitle Sent: Saturday, November 20, 2010 9:54 PM To: Rotary motors in aircraft Subject: [FlyRotary] Re: Exhaust Calcuations Bill, That's one reason why I asked the question about the rotary being more like a 2-stroke when it comes to exhaust design. The other is that there is no exhaust valve to open and close. Instead, there is a revolving door that passes across the exhaust port, never really closing. So, I took Ed's recommendation and ordered the book on how to hot rod the rotary engine. There's a chapter on exhaust design that I'm hoping will explain all this in terms that I can understand. Mark On Sat, Nov 20, 2010 at 8:42 PM, Bill Bradburry wrote: Here is where I show my lack of understanding.. Isn't 40 cu in the size of one rotor and shouldn't this calculation be based on the rotor faces instead of the entire rotor? With a recip engine the exhaust valve on a cylinder opens once every other revolution of the crankshaft, but with the rotary, a rotor face exhausts every revolution of the e-shaft. So there are twice as many pulses in a rotary header pipe as in a recip header. So can the calc for a recip be used for a rotary without some modifications? Bill B _____ From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Ed Anderson Sent: Saturday, November 20, 2010 12:21 PM To: Rotary motors in aircraft Subject: [FlyRotary] Re: Exhaust Calcuations Mark, I did some algebraic manipulations to find HPL based on a selected HPD (tube diameter) and got an answer. However, I am somewhat skeptical of it although it does tend to fit with the general theory of larger dia pipes = shorter lengths. By arbitrary selection an diameter - you automatically select the rpm factor in the equation (but, its hidden in the HPD value). The way you check what your new rpm sweet spot with the arbitrary diameter is to vary the rpm in the first set of equations until you get the length determined by manipulated equation. So the revised equation for 1.8" dia tubes gave 27.58" inches for the HPL. You vary the rpm value in the first equations until you get an HPL of 27.58" and you get an rpm of approx 7900 - so I agree, probably too high for your configuration. Ed From: Mark Steitle Sent: Saturday, November 20, 2010 11:18 AM To: Rotary motors in aircraft Subject: [FlyRotary] Re: Exhaust Calcuations Ed, OK, that answers my question. By going with 1-7/8" OD pipe (.049 wall), it would be tuned for about 7800 rpm. Obviously, this is too high for our purposes. I'll go with 1-5/8 (.063 wall) to shoot for 6700 rpm peak power. This is typically the rpm I see on ground roll and early climb before I start adjusting the prop down to a lower rpm to transition to cruise climb. Have you used the header designer tool available from Burns Stainless? You need to know all the timing numbers, rpm, etc. I may give it a try and see what I come up with. I have a test p-port housing that I made up to see if the tube could be welded to the inner liner. So, I can use that with a spare rotor to verify the EVO and EVC numbers. Mark On Sat, Nov 20, 2010 at 9:55 AM, Ed Anderson wrote: Mark, Here is the corrected spreadsheet - I've colored the changeable cells blue - you can plug in any rpm and EVO. The rest of the cells are protected to keep from accidently overwriting them. Ed Edward L. Anderson Anderson Electronic Enterprises LLC 305 Reefton Road Weddington, NC 28104 http://www.andersonee.com http://www.eicommander.com -- Homepage: http://www.flyrotary.com/ Archive and UnSub: http://mail.lancaironline.net:81/lists/flyrotary/List.html ------=_NextPart_000_0003_01CB8905.EE0248C0 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

It seems that at 6000 rpm, the = rotor would be doing 2000.  that is 720,000 degrees of rotation per min or = 12,000 per second.

So if the exhaust port is 12 = degrees of rotation wide, it would require .001 seconds to open fully, followed by = 50 more degrees of rotation to squish the face to its lowest volume, that is = another 4 ms, (a total of 5 ms) then as the volume is increased, there will be = another 60 degrees or 5 ms before the next apex seal blows by and starts it all = over again.

On a graph, it should look like a tremendous spike followed by a positive then a negative sine wave.  = The whole thing would be 10 ms.

(After thinking about it, maybe it = would be 9 ms with half of the spike on both = ends??)

 

The spike would occur while both = faces are open to the port so the last portion of the negative sine wave would = overlap this spike.

 

I am having trouble getting my head = around what is actually happening.  Then to try and figure out what would = help scavenge, and then figure out how to do that, and then figure out how to = build an exhaust that will do it…

 

I am getting a headache and going = to bed!   :>)

 

Good Luck with this = project!

 

Bill B

From: = Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Mark Steitle
Sent: Saturday, November = 20, 2010 9:54 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: = Exhaust Calcuations

 

Bill, 

 

That's one reason why I asked the question about the rotary = being more like a 2-stroke when it comes to exhaust design.  The other is that = there is no exhaust valve to open and close.  Instead, there is a = revolving door that passes across the exhaust port, never really closing.  So, I = took Ed's recommendation and ordered the book on how to hot rod the rotary = engine.  There's a chapter on exhaust design that I'm hoping will explain = all this in terms that I can understand. 

 

Mark

 

On Sat, Nov 20, 2010 at 8:42 PM, Bill Bradburry <bbradburry@bellsouth.net>= wrote:

Here is where I show my lack of = understanding….

 

Isn’t 40 cu in the size of one rotor and = shouldn’t this calculation be based on the rotor faces instead of the entire rotor?    With a recip engine the exhaust valve on a = cylinder opens once every other revolution of the crankshaft, but with the = rotary, a rotor face exhausts every revolution of the e-shaft.  So there are = twice as many pulses in a rotary header pipe as in a recip = header.

So can the calc for a recip be used for a rotary without = some modifications?

 

Bill B

 

From: Rotary motors in = aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Ed = Anderson
Sent: Saturday, November = 20, 2010 12:21 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: = Exhaust Calcuations

 

Mark, =

 

I did some algebraic manipulations to find HPL based on a selected HPD (tube = diameter) and got an answer.   However, I am somewhat skeptical of it = although it does tend to fit with the general theory of larger dia pipes =3D shorter = lengths.

 

By arbitrary selection an diameter  - you automatically select  the = rpm factor in the equation (but, its hidden in the HPD value).  The way = you check what your new rpm sweet spot  with the arbitrary diameter is = to vary the rpm in the first set of equations until you get the length = determined by manipulated equation.

 

So the revised equation for 1.8" dia tubes gave 27.58" inches for the HPL.  You vary the rpm value in the first equations until you get = an HPL of 27.58" and you get an rpm of approx 7900 - so I agree, probably = too high for your configuration.

 

Ed<= /p>

 

From: Mark Steitle

Sent: = Saturday, November 20, 2010 11:18 AM

Subject: = [FlyRotary] Re: Exhaust Calcuations

 

Ed, =

 

OK, = that answers my question.  By going with 1-7/8" OD pipe (.049 wall), it = would be tuned for about 7800 rpm.  Obviously, this is too high for our = purposes.  I'll go with 1-5/8 (.063 wall) to shoot for 6700 rpm peak power.  This is typically the rpm I see on ground roll and early climb = before I start adjusting the prop down to a lower rpm to transition to cruise = climb.

 

Have = you used the header designer tool available from Burns Stainless?  You need to = know all the timing numbers, rpm, etc.  I may give it a try and see what I = come up with.  I have a test p-port housing that I made up to see if the = tube could be welded to the inner liner.  So, I can use that with a = spare rotor to verify the EVO and EVC numbers.  

 

Mark

 

On = Sat, Nov 20, 2010 at 9:55 AM, Ed Anderson <eanderson@carolina.rr.com> wrote:

Mark, =

 

Here is the corrected spreadsheet - I've colored the changeable cells blue - you can = plug in any rpm and EVO.  The rest of the cells are protected to keep = from accidently overwriting them.

 

Ed<= /p>

 

Edward L. Anderson
Anderson Electronic Enterprises LLC
305 Reefton = Road
Weddington, = NC 28104
http://www.andersonee.com
http://www.eicommander.com=


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