From: "Jim Knoyle"
Date: 1/17/2004 8:00 PM Central Standard Time
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"B2431" wrote in message
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From: "Jim Knoyle"
Date: 1/17/2004 3:48 PM Central Standard Time
Message-id:


"Tarver Engineering" wrote in message
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"Jim Knoyle" wrote in message
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"Tarver Engineering" wrote in message
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"Jim Knoyle" wrote in message
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Hey, Splaps. Next time you are ever near a DADC or it's diagram,
check out what they have at the other end of the tubing connected
to the fitting labeled *TOTAL*. Only ONE pitot tube!

Yep, the term Total means they added two sensors.

Nope, the pitot tube detects static pressure + impact pressure.
Read the book(s).

I have been writing that to you for years, Knoyle. That is why you
seem
such an idiot when you insist a pitot port is a pitot tube.

Total means there is more than one sensor, nothing more.

You really don't understand how that one little opening on the end
of that pointy thing up front can detect static pressure (altitude)
as well as impact pressure (airspeed), do you. That's sad!


The hole on the front only detects pitot pressure. If there are holes on
the
side are for detecting static pressure.


No, sorry Dan, you'll have to refer to a more modern air data computer.
When the label at the top of the ADC switched from pitot to total, the
definition for Total Pressure (Pt) was given as:
"This is a pressure input (from the aircraft pitot probe) which varies
both with altitude and aircraft speed. (Range 3.11 to 42.50 in. Hg.)"
*This was a direct quote from a Honeywell HG280D DADC guide*
The book goes on to explain how the delta Ps is removed to arrive at
a more accurate airspeed. The Ps, whether obtained from the static
port(s) on the probe or flush mounted ports on the fuselage, is fed
through another fitting on the DADC (labeled static) and is something
else entirely. It does factor in to the math.

JK

OK, I see where you are coming from. The pitot pressure DOES vary by altitude.
To compensate for that when measuring airspeed you use static pressure to give
you altitude. Some aircraft detect static pressure from holes on the side of
the pitot tube and others have the static ports located elswhere.

I would be interested in seeing a schematic of your aircraft's pitot-static
systems including DADC. I have never worked on DADC. I did work on the CADC
abomination on the F-4E.

Dan, U.S. Air Force, retired