Why are TE probes so long?

Derrick Steed wrote:
So, you are saying:

1. (TE pressure) = - (pitot pressure) yes?

But at the pitot the pressure = (static pressure) + (dynamic
pressure
head)

So according to your statement (TE pressure) = - [(static pressure)
+
(dynamic pressure head)]

OK, lets agree that the pressure sensed at the static port is
(static
pressure) = (ambient atmospheric pressure)

Then, connecting up an ASI in reverse:

(A) Pressure on static entry to ASI (connected to TE probe) = -
[(static pressure) + (dynamic pressure head)]

(B) Pressure on pitot entry to ASI (connected to static vent) =
(static pressure)

The ASI effectively subtracts the pressure on the static entry from
the pressure on the pitot entry (normally this would result in it
measuring the value of the dynamic pressure head which is
proportional to airspeed - well, for us it is a fairly accurate
measure of it)

So, we have on the ASI a reading proportional to (pressure on pitot
entry) - (pressure on static entry)

Taking values from above this is
(pitot entry) - (static entry) = (B) - (A)
= (static pressure) - [(static pressure) + (dynamic pressure head)]
= - (dynamic pressure head)

Should be: "=(static pressure) - [-(static pressure) - (dynamic
pressure head)]"
= 2(static pressure) + (dynamic pressure head)

Still the wrong result. I think, when people refer to TE probes
providing minus the pitot pressure, they are talking "gauge pressure"
not "absolute pressure"
i.e. the pressure difference from static, such as is measured by most
pressure gauges. (e.g. the gauge on your service station tyre
inflation device)
Cheers, John G.