Return-Path: Sender: To: lml@lancaironline.net Date: Fri, 11 Nov 2005 12:21:33 -0500 Message-ID: X-Original-Return-Path: Received: from [65.54.186.189] (HELO hotmail.com) by logan.com (CommuniGate Pro SMTP 5.0.1) with ESMTP id 827626 for lml@lancaironline.net; Fri, 11 Nov 2005 11:25:30 -0500 Received-SPF: pass receiver=logan.com; client-ip=65.54.186.189; envelope-from=gary21sn@hotmail.com Received: from mail pickup service by hotmail.com with Microsoft SMTPSVC; Fri, 11 Nov 2005 08:20:57 -0800 X-Original-Message-ID: Received: from 71.34.243.188 by BAY16-DAV9.phx.gbl with DAV; Fri, 11 Nov 2005 16:20:57 +0000 X-Originating-IP: [71.34.243.188] X-Originating-Email: [gary21sn@hotmail.com] X-Sender: gary21sn@hotmail.com From: "Gary Edwards" X-Original-To: "Lancair Mailing List" Subject: Re: OAT probe location X-Original-Date: Fri, 11 Nov 2005 08:20:55 -0800 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_009A_01C5E698.D6133E50" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: MSN 9 X-MimeOLE: Produced By MSN MimeOLE V9.10.0011.1703 Seal-Send-Time: Fri, 11 Nov 2005 08:20:55 -0800 X-OriginalArrivalTime: 11 Nov 2005 16:20:57.0480 (UTC) FILETIME=[E5A2B880:01C5E6DB] This is a multi-part message in MIME format. ------=_NextPart_000_009A_01C5E698.D6133E50 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Does any one have any ideas on the best location for the OAT probe? In my Legacy it is installed inside the NACA duct on the pilot side of the plane. The problem is that while on the ground it reads exactly the same as the oil temp probe and exactly the same as the thermometer on the wall of the hanger. However, in flight it always reads much higher than actual outside temperature. For example, yesterday I took the temp reported on ASOS which was 20C, I converted that to 68F. I subtracted the lapse rate of 3C or 5.4F degrees for each thousand feet in the air where it should have been 14F degrees. If I used 2C as the lapse rate it would have been 34F degrees. On my Chelton it read 71F at 10,500'. This happens on every flight so it is not a temp inversion. There must be something wrong with the location. I cannot believe it is getting alot of heat from the engine with all the cold air blasting across the probe through this fresh air vent which is always open. What else could it be????? Any ideas? Is there a better location for the probe? Art, One must be careful that interior heat does not reach the temp probe - = this includes heating the wire near the probe and the mounting surface. = On my 320, using the button housing supplied by Rocky Mountain = Instruments, I have mounted the probe on the wing bottom just forward of = the middle landing gear door opening. Thus, the probe is protected from = the sun when flying with the bottom towards earth and the wires travel = thru the wheel well that pretty much stays at the outside air temp. Has the probe been tested by placing it in ice water that should yield a = temperature close to 0C (32F)?=20 My Rocky Mountain OAT probes are located on top and in the naca cockpit = fresh air ducts on each side of the fuselage. They both work fine in = taxi and in flight and read the same. Gary Edwards LNC2 N21SN=20 ------=_NextPart_000_009A_01C5E698.D6133E50 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

Does=20 any one have any ideas on the best location for
the OAT = probe?

In my=20 Legacy it is installed inside the NACA duct on
the pilot side of = the=20 plane. The problem is that
while on the ground it reads = exactly the=20 same as the
oil temp probe and exactly the same as the = thermometer
on=20 the wall of the hanger. However, in flight it
always reads = much=20 higher than actual outside
temperature.

For example, = yesterday I=20 took the temp reported on
ASOS which was 20C, I converted that to=20 68F. I
subtracted the lapse rate of 3C or 5.4F degrees = for
each=20 thousand feet in the air where it should have
been 14F = degrees. If I=20 used 2C as the lapse rate it
would have been 34F degrees. On = my=20 Chelton it read
71F at 10,500'. This happens on every flight = so it=20 is
not a temp inversion. There must be something = wrong
with the=20 location. I cannot believe it is getting
alot of heat from = the engine=20 with all the cold air
blasting across the probe through this fresh = air=20 vent
which is always open. What else could it be????? =20 Any
ideas? Is there a better location for the=20 probe?

Art,

One must be careful that interior heat does not reach the temp = probe -=20 this includes heating the wire near the probe and the mounting=20 surface. On my 320, using the button housing supplied by Rocky = Mountain=20 Instruments, I have mounted the probe on the wing bottom = just forward=20 of the middle landing gear door opening. Thus, the probe is = protected from=20 the sun when flying with the bottom towards earth and the wires travel = thru the=20 wheel well that pretty much stays at the outside air temp.

Has the probe been tested by placing it in ice water that = should yield=20 a temperature close to 0C (32F)?

My Rocky Mountain OAT probes are located on top and in the = naca=20 cockpit fresh air ducts on each side of the = fuselage. They=20 both work fine in taxi and in flight and read the same.

Gary Edwards

LNC2 N21SN

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