X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mail02.syd.optusnet.com.au ([211.29.132.183] verified) by logan.com (CommuniGate Pro SMTP 5.2c4) with ESMTPS id 2642655 for flyrotary@lancaironline.net; Sat, 12 Jan 2008 18:52:16 -0500 Received-SPF: pass receiver=logan.com; client-ip=211.29.132.183; envelope-from=lendich@optusnet.com.au Received: from george (d58-105-136-230.dsl.nsw.optusnet.com.au [58.105.136.230]) by mail02.syd.optusnet.com.au (8.13.1/8.13.1) with SMTP id m0CNpTgI019556 for ; Sun, 13 Jan 2008 10:51:31 +1100 Message-ID: <004c01c85576$0f990e90$e688693a@george> From: "George Lendich" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Angles Date: Sun, 13 Jan 2008 09:51:31 +1000 MIME-Version: 1.0 Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=original Content-Transfer-Encoding: 7bit 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 Bob, Now I have to know about Radians!!? Just joking - I look it up on the Internet. George (down under) > In addition, "vertical" length and "horizontal" length sort of narrows > it down to a right triangle. > > Another interesting rule of thumb: For small angles the sine, tangent, > and angle are all the same. (The angle is measured in radians rather > than degrees. There are 2*pi radians in 360 degrees.) The smaller the > angle the more accurate the rule of thumb. > > For Georges problem: > tangent is 3/30 = .1 > sine is 3/30.1496 = .09950 (denominator from Pythagorean theorem) > angle in degrees is 5.71059 (from the arc tangent) > so in radians it is 2*pi (5.71059/360) = .099669 > > and the difference between them is less than 0.5 %. > > Bob W. > > > On Sat, 12 Jan 2008 07:25:53 -0700 > Dale Rogers wrote: > >> But Joe, any triangle can be divided into two right triangles. >> >> Dale R. >> >> Joe Ewen wrote: >> > For those who may use this formula, this formula will only work on a >> > right triangle. Please correct me if I am wrong. >> > Joe >> > >> > >> > >> > ----- Original Message ----- >> > *From:* Ed Anderson >> > *To:* Rotary motors in aircraft >> > >> > *Sent:* Saturday, January 12, 2008 8:30 AM >> > *Subject:* [FlyRotary] Re: Angles >> > >> > Hi George, >> > >> > Several folks have responded to your question concerning angles, >> > for what it is worth I also got 5.729 degrees. >> > >> > There are a couple of formulas you can use. One common approach >> > is to use >> > ArcSin, but unless you have a convenient ArcSin function available >> > that can be problematic. >> > >> > So instead I like to use this one for y/r (y being the vertical >> > length of your angle and r the horizontal length) Degrees = y/r >> > * 180/pi = 3/30*180/3.1456 = 5.729 deg. This way you don't >> > need a table/function of ArcSin. >> > >> > Ed >> > >> > >> >> >> -- >> Homepage: http://www.flyrotary.com/ >> Archive and UnSub: >> http://mail.lancaironline.net:81/lists/flyrotary/List.html > > > -- > N93BD - Rotary Powered BD-4 - http://www.bob-white.com > 3.8 Hours Total Time and holding > Cables for your rotary installation - http://roblinstores.com/cables/ > > -- > 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. > Version: 7.5.516 / Virus Database: 269.19.0/1218 - Release Date: > 10/01/2008 1:32 PM >