X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from imo-d04.mx.aol.com ([205.188.157.36] verified) by logan.com (CommuniGate Pro SMTP 5.1.12) with ESMTP id 2348915 for flyrotary@lancaironline.net; Mon, 24 Sep 2007 11:56:59 -0400 Received-SPF: pass receiver=logan.com; client-ip=205.188.157.36; envelope-from=WRJJRS@aol.com Received: from WRJJRS@aol.com by imo-d04.mx.aol.com (mail_out_v38_r9.2.) id q.d31.16b381c7 (52624) for ; Mon, 24 Sep 2007 11:56:15 -0400 (EDT) Received: from webmail-db18 (webmail-db18.webmail.aol.com [205.188.105.83]) by cia-d12.mx.aol.com (v119.9) with ESMTP id MAILCIAD122-cd9046f7de1e1af; Mon, 24 Sep 2007 11:56:14 -0400 References: To: flyrotary@lancaironline.net Subject: Re: [FlyRotary] Re: Area of a circle Date: Mon, 24 Sep 2007 11:56:14 -0400 In-Reply-To: X-MB-Message-Source: WebUI MIME-Version: 1.0 From: wrjjrs@aol.com X-MB-Message-Type: User Content-Type: multipart/alternative; boundary="--------MB_8C9CCDA91A8E60D_648_118CB_webmail-db18.sysops.aol.com" X-Mailer: AOL WebMail 30583 Received: from 65.161.241.3 by webmail-db18.sysops.aol.com (205.188.105.83) with HTTP (WebMailUI); Mon, 24 Sep 2007 11:56:14 -0400 Message-Id: <8C9CCDA91A8E60D-648-8B6F@webmail-db18.sysops.aol.com> X-AOL-IP: 205.188.105.83 X-Spam-Flag: NO ----------MB_8C9CCDA91A8E60D_648_118CB_webmail-db18.sysops.aol.com Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii" George, You need to solve for the area of the circular segment opened by the slide throttle. The formula is???????? A=1/2[rl-c(r-h)] A=area, r-radius, l=lenght on the perimeter, c=chord, h=chord height Since lenght on the perimeter can be tough to determine, there is an alternate formula. There is a slight error (less than .1%) A=4h^2/3 times sq root of c^2/4h^2+0.392 area equals four times h squared divided by three times the square root of c squared divided by 4 times h squared plus 0.392 (pg 75 mahninery's handbook 21st ed.) That will give you the cordal area of 1/2 of the opening obviously. You can figure the cross-sectional area of the needle to remove. You can do openings at various throttle openings and then graph of extrapolate the points between. Good luck! Bill Jepson -----Original Message----- From: George Lendich To: Rotary motors in aircraft Sent: Sat, 22 Sep 2007 4:55 pm Subject: [FlyRotary] Re: Area of a circle ?Al, I am using a slide throttle and initially thought I would just do trial and error, but figured if I could just get a handle on variables it would help with the initial taper grind on the needle. I guess I could just go linier and see how that goes. I could use an O2 sensor to check fuel/air ratio, then regrind a new needle. George (down under) ________________________________________________________________________ Email and AIM finally together. You've gotta check out free AOL Mail! - http://mail.aol.com ----------MB_8C9CCDA91A8E60D_648_118CB_webmail-db18.sysops.aol.com Content-Transfer-Encoding: 7bit Content-Type: text/html; charset="us-ascii" George,
You need to solve for the area of the circular segment opened by the slide throttle. The formula is         A=1/2[rl-c(r-h)]
A=area, r-radius, l=lenght on the perimeter, c=chord, h=chord height
Since lenght on the perimeter can be tough to determine, there is an alternate formula. There is a slight error (less than .1%)

A=4h^2/3 times sq root of c^2/4h^2+0.392
area equals four times h squared divided by three times the square root of c squared divided by 4 times h squared plus 0.392
(pg 75 mahninery's handbook 21st ed.)

That will give you the cordal area of 1/2 of the opening obviously. You can figure the cross-sectional area of the needle to remove. You can do openings at various throttle openings and then graph of extrapolate the points between. Good luck!
Bill Jepson


-----Original Message-----
From: George Lendich <lendich@optusnet.com.au>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Sent: Sat, 22 Sep 2007 4:55 pm
Subject: [FlyRotary] Re: Area of a circle

 Al,
I am using a slide throttle and initially thought I would just do trial and error, but figured if I could just get a handle on variables it would help with the initial taper grind on the needle. I guess I could just go linier and see how that goes. I could use an O2 sensor to check fuel/air ratio, then regrind a new needle.
George (down under)

Email and AIM finally together. You've gotta check out free AOL Mail!
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