Why are TE probes so long?

I'm sure somebody may correct me, but as I recall, the TE probe produces
a signal equal and opposite of the pitot (total pressure). Unless you have
separated flow, or flow inside the boundary layer, the total pressure doesn't
change anywhere around the plane. It would seem to me to be a case
where angular changes (due to deflected airflow) would be the cause
of the shift in the TE pressure. The shape and angle of the TE probe is
not as forgiving as the pitot end.



In article ,
wrote:
(Hank Nixon) wrote:

Experience has shown that TE sensors need to be at least 1/2 chord
length in front of the fin to avoid negative effects.

In addition to the disturbance from the tail surfaces, there
can be disturbances from the wing. You usually want your
probe above an imaginary line connecting the leading edge of
the horizontal stabilizer to the wing. Length (and turning
the tip up) helps get the probe into that undisturbed air.
Todd Pattist - "WH" Ventus C
(Remove DONTSPAMME from address to email reply.)