X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from fmailhost03.isp.att.net ([207.115.11.53] verified) by logan.com (CommuniGate Pro SMTP 5.3.10) with ESMTP id 4586734 for flyrotary@lancaironline.net; Sat, 20 Nov 2010 21:43:33 -0500 Received-SPF: none receiver=logan.com; client-ip=207.115.11.53; envelope-from=bbradburry@bellsouth.net Received: from desktop (adsl-85-148-241.mco.bellsouth.net[98.85.148.241]) by isp.att.net (frfwmhc03) with SMTP id <20101121024256H03002u2b8e>; Sun, 21 Nov 2010 02:42:56 +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 21:42:56 -0500 Message-ID: <106BFC6AC89743AAA6F9689EA245F73D@Desktop> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_000A_01CB88FB.E51E05F0" X-Mailer: Microsoft Office Outlook 11 Thread-Index: AcuI12ORkb5wxmnnSP6heCJ1s/auAAATPqMQ X-MimeOLE: Produced By Microsoft MimeOLE V6.0.6001.18049 This is a multi-part message in MIME format. ------=_NextPart_000_000A_01CB88FB.E51E05F0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit 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_000A_01CB88FB.E51E05F0 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

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

 

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

 

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.h= tml

 

------=_NextPart_000_000A_01CB88FB.E51E05F0--