X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Mon, 11 Sep 2006 11:07:07 -0400 Message-ID: X-Original-Return-Path: Received: from [68.98.211.24] (HELO systems3.net) by logan.com (CommuniGate Pro SMTP 5.1c.3) with ESMTP id 1374130 for lml@lancaironline.net; Mon, 11 Sep 2006 11:06:18 -0400 Received-SPF: none receiver=logan.com; client-ip=68.98.211.24; envelope-from=cberland@systems3.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----_=_NextPart_001_01C6D5B3.BCED87C9" Content-class: urn:content-classes:message X-MimeOLE: Produced By Microsoft Exchange V6.5 Subject: [LML] Do the Dew Point affect the "Do" point - Like "Do" it go slower? Faster? X-Original-Date: Mon, 11 Sep 2006 08:05:36 -0700 X-Original-Message-ID: <87C33F695961494D886EB3B6C8A476510B905D@s3server.Systems3.local> X-MS-Has-Attach: X-MS-TNEF-Correlator: Thread-Topic: [LML] Do the Dew Point affect the "Do" point - Like "Do" it go slower? Faster? Thread-Index: AcbVXA84S67W+4zMQZ+y1x+z+qDJLAAVnJCg From: "Craig Berland" X-Original-To: "Lancair Mail List" This is a multi-part message in MIME format. ------_=_NextPart_001_01C6D5B3.BCED87C9 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable =20 Scott Krueger wrote: OK performance fans - recently I became interested in aircraft/engine performance related to air density. Most specifically, related to the dew point. I was lucky enough to find an instrument (about $80) that displays the air temperature, %humidity and dew point temperature. The dew point is important to understand the air density difference from the ISA standard predicted only by air temperature at some altitude. =20 =20 Scott, you are correct. When correcting for power one must reduce the observed Intake Pressure by the Vapor Pressure. In dry air the Vapor Pressure is "zero" and can increase to over 1.0 In Hg in hot moist air. When the dry bulb is 100 deg F and the wet bulb is 100 deg F, the Vapor Pressure is 1.92 In Hg. (You know, a nice day in Florida) Craig Berland ------_=_NextPart_001_01C6D5B3.BCED87C9 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable
 
Scott Krueger  wrote:  OK performance = fans -=20 recently I became interested in aircraft/engine performance related to = air=20 density.  Most specifically, related to the dew point.  I was = lucky=20 enough to find an instrument (about $80) that displays the = air temperature,=20 %humidity and dew point temperature.  The dew point is important to = understand the air density difference from the ISA standard=20 predicted only by air temperature at some altitude.  =
 
Scott, you are correct.  When = correcting for power one must reduce the observed Intake Pressure by the = Vapor=20 Pressure.  In dry air the Vapor Pressure is "zero" and can increase = to over=20 1.0 In Hg in hot moist air.  When the dry bulb is 100 deg F and the = wet=20 bulb is 100 deg F, the Vapor Pressure is 1.92 In Hg. (You know, a nice = day in=20 Florida)
Craig=20 Berland
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