X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Tue, 24 Jun 2008 13:30:36 -0400 Message-ID: X-Original-Return-Path: Received: from smtp123.sbc.mail.sp1.yahoo.com ([69.147.64.96] verified) by logan.com (CommuniGate Pro SMTP 5.2.3) with SMTP id 2980050 for lml@lancaironline.net; Sun, 22 Jun 2008 22:16:50 -0400 Received: (qmail 91285 invoked from network); 23 Jun 2008 02:16:46 -0000 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=sbcglobal.net; h=Received:X-YMail-OSG:X-Yahoo-Newman-Property:Message-ID:From:To:Subject:Date:MIME-Version:Content-Type:X-Priority:X-MSMail-Priority:X-Mailer:X-MimeOLE; b=mfgILcs2Yr7MfobJ4rHsuwY+qcMroleI/01C7JbhjPiTvkob3HbaoxJpsABrjXagxF8O6aAkAuCe1mplXSPylG6A0iKnEZCf6D4Lrd2bMa9rr2tR8IMOVNYhIrJ8aV+buIbr7gLddTdlEIDSa0SWMoHoWaWJAQYTCwl/zWcHowQ= ; Received: from unknown (HELO Computerroom) (elippse@sbcglobal.net@75.6.2.175 with login) by smtp123.sbc.mail.sp1.yahoo.com with SMTP; 23 Jun 2008 02:16:45 -0000 X-YMail-OSG: HrvImLEVM1kG9D9_9m.2Dwwv55EtgFJJTHCzLwTdy7.lTdBbPHWAY6h_EoQBBYBcgNAS7iCl6KssW2Tj2e0tWX32iW0srbQQtfrSY3SWNA-- X-Yahoo-Newman-Property: ymail-3 X-Original-Message-ID: <000801c8d4d7$3c016280$af02064b@Computerroom> From: "Paul Lipps" X-Original-To: "Marv Kaye" Subject: IAS errors X-Original-Date: Sun, 22 Jun 2008 19:17:04 -0700 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0005_01C8D49C.8E4B37E0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.3138 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3198 This is a multi-part message in MIME format. ------=_NextPart_000_0005_01C8D49C.8E4B37E0 Content-Type: text/plain; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable It's much easier to do the upwind-downwind speed runs and you get the = results immediately. First, call weather and get the forecast winds and = temperatures for the altitude(s) you are testing at. Convert the true = wind direction to magnetic. Fly your GPS ground track, not heading, into = and with the wind, recording your groundspeed each way. Average the two = of them and and there's your TAS. Don't worry about forecast wind error = unless it's more than 20k at 90 deg, and even then at TAS greater than = 200 mph your error will be 1 mph or less. To get density altitude, use = this: dalt =3D baro altitude + 113.4' x (OATC + 1.88E-3 x altitude - = 15C). Then get rho ratio: rr =3D (1 - 6.88E-6 x dalt)^4.256. Multiply = the square root of rr times TAS to get IAS. 'Nuthin' to it! ------=_NextPart_000_0005_01C8D49C.8E4B37E0 Content-Type: text/html; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable
It's much easier to do the upwind-downwind speed = runs and=20 you get the results immediately. First, call weather and get the = forecast winds=20 and temperatures for the altitude(s) you are testing at. Convert the = true wind=20 direction to magnetic. Fly your GPS ground track, not heading, into and = with the=20 wind, recording your groundspeed each way. Average the two of them and = and=20 there's your TAS. Don't worry about forecast wind error unless it's = more=20 than 20k at 90 deg, and even then at TAS greater than 200 mph your error = will be=20 1 mph or less. To get density altitude, use this: dalt =3D baro = altitude +=20 113.4' x (OATC + 1.88E-3 x altitude - 15C). Then get rho ratio: rr =3D = (1 -=20 6.88E-6 x dalt)^4.256. Multiply the square root of rr times TAS to get = IAS.=20 'Nuthin' to it!
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