X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mail35.syd.optusnet.com.au ([211.29.133.51] verified) by logan.com (CommuniGate Pro SMTP 5.1.12) with ESMTPS id 2346425 for flyrotary@lancaironline.net; Sat, 22 Sep 2007 20:07:03 -0400 Received-SPF: none receiver=logan.com; client-ip=211.29.133.51; envelope-from=lendich@optusnet.com.au Received: from george (d220-237-243-228.dsl.nsw.optusnet.com.au [220.237.243.228]) by mail35.syd.optusnet.com.au (8.13.1/8.13.1) with SMTP id l8N06GPo021264 for ; Sun, 23 Sep 2007 10:06:17 +1000 Message-ID: <004b01c7fd75$95b904c0$e4f3eddc@george> From: "George Lendich" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Area of a circle Date: Sun, 23 Sep 2007 10:06:25 +1000 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0048_01C7FDC9.66B48970" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.2180 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 X-Antivirus: avast! (VPS 0657-0, 12/12/2006), Outbound message X-Antivirus-Status: Clean This is a multi-part message in MIME format. ------=_NextPart_000_0048_01C7FDC9.66B48970 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Thanks Ed, I'm looking at it - again! Mind you I'm wanting to use a slide throttle, so the butterfly thickness = and rod are not a factor in my non-venturi, straight through 44 mm dia = carb design. George ----- Original Message -----=20 From: Ed Anderson=20 To: Rotary motors in aircraft=20 Sent: Sunday, September 23, 2007 2:25 AM Subject: [FlyRotary] Re: Area of a circle I agree with Al, George. =20 However, if you wish to enjoy the thrill of calculating that area = (which is not a trivial task), here is a document that has all the = information (formulas) you need. http://med.ee.nd.edu/MED5/PAPERS/S5_3/S5_3.PDF Now if you are willing to assume that the throttle plate = thickness and its rod are not a factor (maybe not a bad real-world = assumption just to get the area of the opening - but different story = regarding its effect on air flow which is why Al's suggestion is a good = one), I have attached a spreadsheet with this simplification of the = math. Ed ----- Original Message -----=20 From: Al Gietzen=20 To: Rotary motors in aircraft=20 Sent: Saturday, September 22, 2007 12:06 PM Subject: [FlyRotary] Re: Area of a circle George; Determining the area of the opening of a circular butterfly with = position is certainly complex enough; but the flow is likely not = directly proportional because of the complexities of the flow = characteristics and pressure changes. I would think measuring it is = really the only way. Do you have access to a flow bench? Sorry; probably not very helpful, Al G -----Original Message----- From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] = On Behalf Of George Lendich Sent: Friday, September 21, 2007 9:21 PM To: Rotary motors in aircraft Subject: [FlyRotary] Area of a circle Chaps,=20 I am trying to work out the area of carb inlet as it is opened = incrementally. This involves the overlapped portion of two circles, as well as, a = circle cut into slices ( straight cuts). This should give me an indication of the linier or otherwise, volume = of air as it sweeps through the carb. This then should indicate the shape of the grind of the needle in = maintaining continuity of the mixture ratio of fuel to air. Any helpers with this one!? George (down under) -------------------------------------------------------------------------= ----- -- Homepage: http://www.flyrotary.com/ Archive and UnSub: = http://mail.lancaironline.net:81/lists/flyrotary/List.html -------------------------------------------------------------------------= ----- No virus found in this incoming message. Checked by AVG Free Edition.=20 Version: 7.5.488 / Virus Database: 269.13.28/1021 - Release Date: = 21/09/2007 2:02 PM ------=_NextPart_000_0048_01C7FDC9.66B48970 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Thanks Ed,
I'm looking at it = - again!
Mind you I'm wanting to use a slide = throttle, so=20 the butterfly thickness and rod are not a factor in my non-venturi, = straight=20 through 44 mm dia carb design.
George
----- Original Message -----
From:=20 Ed=20 Anderson
Sent: Sunday, September 23, = 2007 2:25=20 AM
Subject: [FlyRotary] Re: Area = of a=20 circle

I agree with Al, George. 
 
However, if you wish to enjoy the thrill of = calculating=20 that area (which is not a trivial task), here is a document that has = all the=20 information (formulas) you need.
 
http://med.ee.nd.= edu/MED5/PAPERS/S5_3/S5_3.PDF
 
     Now if you are = willing to=20 assume that the throttle plate  thickness and its rod are not a = factor=20 (maybe not a bad real-world assumption just to get the = area of=20 the opening - but different story regarding its effect on air flow = which is=20 why Al's suggestion is a good one), I have attached a spreadsheet with = this=20 simplification of the math.
 
Ed
 
----- Original Message -----
From:=20 Al = Gietzen=20
To: Rotary motors in = aircraft=20
Sent: Saturday, September 22, = 2007=20 12:06 PM
Subject: [FlyRotary] Re: Area = of a=20 circle

George;

 

Determining the=20 area of the opening of a circular butterfly with position is = certainly=20 complex enough; but the flow is likely not directly proportional = because of=20 the complexities of the flow characteristics and pressure changes. =  I=20 would think measuring it is really the only way.  Do you have = access to=20 a flow bench?

 

Sorry; = probably=20 not very helpful,

 

Al=20 G

 

-----Original=20 Message-----
From: Rotary=20 motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of George = Lendich
Sent: Friday, September 21, = 2007 9:21=20 PM
To: Rotary = motors in=20 aircraft
Subject: = [FlyRotary] Area of a circle

 

Chaps, 

I am trying to work = out the area=20 of carb inlet as it is opened incrementally.

 

This involves the = overlapped=20 portion of two circles, as well as, a circle cut into slices ( = straight=20 cuts).

 

This should give me an = indication of the linier or otherwise, volume of air as it sweeps = through=20 the carb.

 

This then should = indicate the=20 shape of the grind of the needle in maintaining continuity of = the=20 mixture ratio of fuel to air.

 

Any helpers with this=20 one!?

George (down=20 under)

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

No virus found in this incoming message.
Checked by AVG Free = Edition.
Version: 7.5.488 / Virus Database: 269.13.28/1021 - = Release Date:=20 21/09/2007 2:02 PM
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