Almost a statisic

"Gary Drescher" wrote in message
...
"dlevy" wrote in message
...
I had a pitot/static problem as a new PPL (clear weather) that was very
exciting. Airspeed was fine till about 20 feet off the ground. At that
point airspeed would start dropping. I kept pushing the nose over and
airspeed kept dropping. I then realized rpm's were normal, the propellor
was attached, and everything sounded right. It scared the bejezus outta
me. Turned out to be water in the static line. Afterwards, I realized I
was way too dependant on that one indicator. Had it been IMC, it could
have been very ugly.

Hm, shouldn't a blocked static line cause the airspeed indicator to show
an
increase in airspeed, rather than a decrease, with increasing altitude?


It would indicate a lower airspeed.

The pitot ram air pressure for a given airspeed decreases with higher
altitude. If the static port were blocked (at say, the takeoff altitude),
the airspeed would "indicate" a lower airspeed since the pitot pressure has
dropped for that airspeed as the plane gains altitude. As another poster
commented, the only altitude where the ASI is accurate is at the altitude
where the blockage occurred.

The pitot ram air pressure for a given airspeed decreases with higher
altitude. If the static port were blocked (at say, the takeoff altitude),
the airspeed would "indicate" a lower airspeed since the pitot pressure has
dropped for that airspeed as the plane gains altitude. As another poster
commented, the only altitude where the ASI is accurate is at the altitude
where the blockage occurred.


Not really. You should remain at the same pressure altitude. If you
travel to an area with higher or lower pressure, you would be
surprised.

"Sriram Narayan" wrote in message
news:1105574315.223629d9c9b6178c7b6b555f5ecac8c3@t eranews...

"Gary Drescher" wrote in message

Hm, shouldn't a blocked static line cause the airspeed indicator to show
an
increase in airspeed, rather than a decrease, with increasing altitude?


It would indicate a lower airspeed.

The pitot ram air pressure for a given airspeed decreases with higher
altitude. If the static port were blocked (at say, the takeoff altitude),
the airspeed would "indicate" a lower airspeed since the pitot pressure
has
dropped for that airspeed as the plane gains altitude. As another poster
commented, the only altitude where the ASI is accurate is at the altitude
where the blockage occurred.

Oops. Yes, of course. Thanks.

--Gary

"Sriram Narayan" wrote in message
news:1105574315.223629d9c9b6178c7b6b555f5ecac8c3@t eranews...

"Gary Drescher" wrote in message
...
"dlevy" wrote in message
...
I had a pitot/static problem as a new PPL (clear weather) that was very
exciting. Airspeed was fine till about 20 feet off the ground. At that
point airspeed would start dropping. I kept pushing the nose over and
airspeed kept dropping. I then realized rpm's were normal, the
propellor
was attached, and everything sounded right. It scared the bejezus outta
me. Turned out to be water in the static line. Afterwards, I realized I
was way too dependant on that one indicator. Had it been IMC, it could
have been very ugly.

Hm, shouldn't a blocked static line cause the airspeed indicator to show
an
increase in airspeed, rather than a decrease, with increasing altitude?


It would indicate a lower airspeed.

The pitot ram air pressure for a given airspeed decreases with higher
altitude. If the static port were blocked (at say, the takeoff altitude),
the airspeed would "indicate" a lower airspeed since the pitot pressure
has
dropped for that airspeed as the plane gains altitude. As another poster
commented, the only altitude where the ASI is accurate is at the altitude
where the blockage occurred.



Actually, the OP didn't say anything about the static line being blocked, he
said that it had water in it. The static pressure availilble at the
instruments still changes in the proper direction if the static (or pitot)
line has water in it, it just changes at a different (usually lower) rate.

Mike
MU-2
Helio Courier

"Mike Rapoport" wrote in message
ink.net...

"Sriram Narayan" wrote in message
news:1105574315.223629d9c9b6178c7b6b555f5ecac8c3@t eranews...

"Gary Drescher" wrote in message
...
"dlevy" wrote in message
...
I had a pitot/static problem as a new PPL (clear weather) that was
very
exciting. Airspeed was fine till about 20 feet off the ground. At
that
point airspeed would start dropping. I kept pushing the nose over and
airspeed kept dropping. I then realized rpm's were normal, the
propellor
was attached, and everything sounded right. It scared the bejezus
outta
me. Turned out to be water in the static line. Afterwards, I realized
I
was way too dependant on that one indicator. Had it been IMC, it
could
have been very ugly.

Hm, shouldn't a blocked static line cause the airspeed indicator to
show
an
increase in airspeed, rather than a decrease, with increasing altitude?


It would indicate a lower airspeed.

The pitot ram air pressure for a given airspeed decreases with higher
altitude. If the static port were blocked (at say, the takeoff
altitude),
the airspeed would "indicate" a lower airspeed since the pitot pressure
has
dropped for that airspeed as the plane gains altitude. As another poster
commented, the only altitude where the ASI is accurate is at the
altitude
where the blockage occurred.



Actually, the OP didn't say anything about the static line being blocked,
he
said that it had water in it. The static pressure availilble at the
instruments still changes in the proper direction if the static (or pitot)
line has water in it, it just changes at a different (usually lower) rate.


Mike
MU-2
Helio Courier



I don't disagree. I was responding to Gary Drescher's post (not the OP)
where he talked about a blocked static port, not one which may have water in
it, which like you say behaves like a partially blocked port but could be
even more erratic.