Jeffrey, I have one probe on the wing and another on the fuselage bottom near the choke point of the fuselage (Legacy).  The fuselage reads about 8C (celsius) higher than the wing probe.  I attribute that to engine heat, exhaust, prop thrust and my breath.    I think the wing is the only logical place for temp measurement.

Paul
On 2012-08-19, at 9:36 AM, jeffrey liegner <liegner@ptd.net> wrote:

> Recall my question (same subject) about the accuracy of OAT, and its efect on TAS and Winds.  SInce I rendere pireps including winds and OAT, the accuracy of this report is now in question.  Many have suggested reloacting the OAT to another place, different from the Lancair recommendation along the fuselage.  This is not an easy thing, putting the probe out on the wing, wiring coming into and through the wing root, into the pressure vessel (different from the current OAT location).
>
> I performed the flight TAS calculation recommended by several.  Whether three measurements with headings 120 degrees apart, or three orthogonal headings, the results are the same.
>
>
> The Chelton presents a TAS 216 and the calculator renders TAS 205 based on the n flight measurement.
>
> I wonder if I can change the compressibility quotient used by Chelton to adjust the OAT reading.
>
> Suggestions?
>
> Jeff L
> N334P
>
> --
> For archives and unsub http://mail.lancaironline.net:81/lists/lml/List.html