"The CO" wrote in message =
...
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"fudog50" wrote in message
...
snip
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IIRC, the only indicator that had both pitot and static inputs
was the VSI/Rate of climb indicator and the internal bellows in the
gauge performed the differential action.
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Ok, what they taught me was that the VSI ran on static pressure and
*metered* static pressure.
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I'm not aware that pitot pressure (which is directly related to
airspeed) would be of use for a VSI.
Can you explain how that would be used in a VSI? I can't see any
connection.
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The only time pitot pressure =3D static pressure is if the aircraft is
stationary and there is no wind.
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The difference between static port pressure and static pressure that =
was
restricted as to the rate it
could alter (inside the VSI) by way of a port that is very small in
comparision to the main static port gives
the rate that pressure (and therefore altitude) is changing, giving =
you
a rate of climb or descent.
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Airspeed has pitot inputs only.
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ISTR that an ASI that can give you a TAS instead of an IAS had static
pressure and temp sensors
in addition to the pitot inputs, *or* it was in some way
coupled to the altimeter, so that it could show a corrected TAS based =
on
density
altitude, but I've never actually had one in my hand. IIRC, a =
PA28-180R
I used to fly out
of Broken Hill many years ago had a TAS meter fitted, but I wasn't =
aware
of exactly how it worked at the time.
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Baro Alt. has static port input only.
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Yup. An altimeter is basically an aneroid barometer.
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Wish I could draw you a
diagram on here, it would explain everything.
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It always helps.
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The CO
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You're just trying to be nice, aren't you, CO?
We all know the fudog's memory failed him this time.

One thing -- The pitot pressure isn't "directly related to airspeed",
(and we know you meant IAS, not TAS).
The differential pressure is really related to the airspeed *squared*.
---JRC---