Return-Path: Sender: To: lml@lancaironline.net Date: Thu, 10 Nov 2005 13:00:06 -0500 Message-ID: X-Original-Return-Path: Received: from imo-m21.mx.aol.com ([64.12.137.2] verified) by logan.com (CommuniGate Pro SMTP 5.0.1) with ESMTP id 826028 for lml@lancaironline.net; Thu, 10 Nov 2005 09:03:26 -0500 Received-SPF: pass receiver=logan.com; client-ip=64.12.137.2; envelope-from=Sky2high@aol.com Received: from Sky2high@aol.com by imo-m21.mx.aol.com (mail_out_v38_r6.3.) id q.1c2.3586270a (18555) for ; Thu, 10 Nov 2005 09:02:37 -0500 (EST) From: Sky2high@aol.com X-Original-Message-ID: <1c2.3586270a.30a4acfd@aol.com> X-Original-Date: Thu, 10 Nov 2005 09:02:37 EST Subject: Re: [LML] OAT probe location X-Original-To: lml@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="-----------------------------1131631357" X-Mailer: 9.0 Security Edition for Windows sub 5300 X-Spam-Flag: NO -------------------------------1131631357 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit In a message dated 11/10/2005 6:37:41 A.M. Central Standard Time, flycassutts@yahoo.com writes: 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)? Scott Krueger AKA Grayhawk Lancair N92EX IO320 SB 89/96 Aurora, IL (KARR) -------------------------------1131631357 Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable
In a message dated 11/10/2005 6:37:41 A.M. Central Standard Time,=20 flycassutts@yahoo.com writes:
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>Does any=20 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 t= he=20 same as the
oil temp probe and exactly the same as the thermometer
o= n=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
eac= h=20 thousand feet in the air where it should have
been 14F degrees.  I= f 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 i= t=20 is
not a temp inversion.  There must be something wrong
with th= e=20 location.  I cannot believe it is getting
alot of heat from the en= gine=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=20 includes heating the wire near the probe and the mounting surface. = ; On=20 my 320, using the button housing supplied by Rocky Mountain Instruments, I h= ave=20 mounted the probe on the wing bottom just forward of the middle=20 landing gear door opening.  Thus, the probe is protected from the sun w= hen=20 flying with the bottom towards earth and the wires travel thru the wheel wel= l=20 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=20 temperature close to 0C (32F)?=20
 
Scott Krueger=20 AKA Grayhawk
Lancair N92EX IO320 SB 89/96
Aurora, IL=20 (KARR)



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