| Topic: |
Science > Physics |
| User: |
"" |
| Date: |
16 Aug 2005 05:12:36 PM |
| Object: |
pressurized airplane cabins |
If the air in a passenger jet is pressurized to 10,000 feet or so, why
do my ears start to "pop" (or "un-pop") nearly as soon as the plane
starts its descent, still practically at it's cruising altitude of
30,000+ feet. I assume it has to do with the way the pressure is
maintained by the engines compressing outside air so any variation in
engine speed, plane speed, altitude would alter somewhat the cabin
pressure. Is the "pressurized to 10,000 feet" only true more or less?
How much variation is there in a normal flight?
Dave
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| User: "Sam Wormley" |
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| Title: Re: pressurized airplane cabins |
16 Aug 2005 05:48:05 PM |
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wrote:
If the air in a passenger jet is pressurized to 10,000 feet or so, why
do my ears start to "pop" (or "un-pop") nearly as soon as the plane
starts its descent, still practically at it's cruising altitude of
30,000+ feet. I assume it has to do with the way the pressure is
maintained by the engines compressing outside air so any variation in
engine speed, plane speed, altitude would alter somewhat the cabin
pressure. Is the "pressurized to 10,000 feet" only true more or less?
How much variation is there in a normal flight?
Dave
The cabin pressure is for the survivability of the crew and
passengers who wouldn't get enough oxygen otherwise... nothing
to do with engine function.
When a plain starts a decent, cabin pressure will also start
to change in a gradual process to bring it back to the nominal
ground level pressure of the landing site.
.
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| User: "" |
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| Title: Re: pressurized airplane cabins |
16 Aug 2005 07:57:20 PM |
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I'll try to make myself a little more clear. If the plane is
pressurized to 10,000 feet altitude, then there should be no difference
in air pressure within the cabin while the plane is between 10,000 feet
and 40,000 feet. Therefore, my question: "Why do my ears pop (respond
to changing pressure) nearly as soon as the plane starts to drop from
its cruising altitude, long before it reaches the 10,000 foot
elevation?
Dave Perry
Sam Wormley wrote:
judamd@aol.com wrote:
If the air in a passenger jet is pressurized to 10,000 feet or so, why
do my ears start to "pop" (or "un-pop") nearly as soon as the plane
starts its descent, still practically at it's cruising altitude of
30,000+ feet. I assume it has to do with the way the pressure is
maintained by the engines compressing outside air so any variation in
engine speed, plane speed, altitude would alter somewhat the cabin
pressure. Is the "pressurized to 10,000 feet" only true more or less?
How much variation is there in a normal flight?
Dave
The cabin pressure is for the survivability of the crew and
passengers who wouldn't get enough oxygen otherwise... nothing
to do with engine function.
When a plain starts a decent, cabin pressure will also start
to change in a gradual process to bring it back to the nominal
ground level pressure of the landing site.
.
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| User: "Sam Wormley" |
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| Title: Re: pressurized airplane cabins |
16 Aug 2005 08:23:13 PM |
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wrote:
I'll try to make myself a little more clear. If the plane is
pressurized to 10,000 feet altitude, then there should be no difference
in air pressure within the cabin while the plane is between 10,000 feet
and 40,000 feet. Therefore, my question: "Why do my ears pop (respond
to changing pressure) nearly as soon as the plane starts to drop from
its cruising altitude, long before it reaches the 10,000 foot
elevation?
Dave Perry
I'll do likewise--try to make myself a little more clear.
Consider the possibility that going from 40000 to 35000 feet
the cabin pressure changes from the equivalent of 10000 to 9000
feet.
Why are you insisting on a 1-1 pressure correspondence between
0 and 10000 ft?
Sam Wormley wrote:
wrote:
If the air in a passenger jet is pressurized to 10,000 feet or so, why
do my ears start to "pop" (or "un-pop") nearly as soon as the plane
starts its descent, still practically at it's cruising altitude of
30,000+ feet. I assume it has to do with the way the pressure is
maintained by the engines compressing outside air so any variation in
engine speed, plane speed, altitude would alter somewhat the cabin
pressure. Is the "pressurized to 10,000 feet" only true more or less?
How much variation is there in a normal flight?
Dave
The cabin pressure is for the survivability of the crew and
passengers who wouldn't get enough oxygen otherwise... nothing
to do with engine function.
When a plain starts a decent, cabin pressure will also start
to change in a gradual process to bring it back to the nominal
ground level pressure of the landing site.
.
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| User: "NightsoilDalits@RyugyongHotel" |
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| Title: Re: pressurized airplane cabins |
16 Aug 2005 08:34:03 PM |
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"Sam Wormley" <swormley1@mchsi.com> wrote in message
news:5kwMe.258421$_o.30404@attbi_s71...
judamd@aol.com wrote:
I'll try to make myself a little more clear. If the plane is
pressurized to 10,000 feet altitude, then there should be no difference
in air pressure within the cabin while the plane is between 10,000 feet
and 40,000 feet. Therefore, my question: "Why do my ears pop (respond
to changing pressure) nearly as soon as the plane starts to drop from
its cruising altitude, long before it reaches the 10,000 foot
elevation?
Dave Perry
I'll do likewise--try to make myself a little more clear.
Consider the possibility that going from 40000 to 35000 feet
the cabin pressure changes from the equivalent of 10000 to 9000
feet.
Why are you insisting on a 1-1 pressure correspondence between
0 and 10000 ft?
They use a compressor to pressurize the cabin above 10,000 feet.
It is almost the same as a supercharger on a car, twin screws.
They follow pressurization curves for assent and descent.
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| User: "" |
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| Title: Re: pressurized airplane cabins |
16 Aug 2005 08:34:51 PM |
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wrote:
I'll try to make myself a little more clear. If the plane is
pressurized to 10,000 feet altitude, then there should be no difference
in air pressure within the cabin while the plane is between 10,000 feet
and 40,000 feet. Therefore, my question: "Why do my ears pop (respond
to changing pressure) nearly as soon as the plane starts to drop from
its cruising altitude, long before it reaches the 10,000 foot
elevation?
Dave Perry
Sam Wormley wrote:
wrote:
If the air in a passenger jet is pressurized to 10,000 feet or so, why
do my ears start to "pop" (or "un-pop") nearly as soon as the plane
starts its descent, still practically at it's cruising altitude of
30,000+ feet. I assume it has to do with the way the pressure is
maintained by the engines compressing outside air so any variation in
engine speed, plane speed, altitude would alter somewhat the cabin
pressure. Is the "pressurized to 10,000 feet" only true more or less?
How much variation is there in a normal flight?
Dave
The cabin pressure is for the survivability of the crew and
passengers who wouldn't get enough oxygen otherwise... nothing
to do with engine function.
When a plain starts a decent, cabin pressure will also start
to change in a gradual process to bring it back to the nominal
ground level pressure of the landing site.
Airliners (at least US airliners, I have no idea what Air Botswana
might do) are pressurized to about 8,000 feet.
The only part Sam left out is the pressure is supposed to be increased
at such a rate that what you describe doesn't happen.
The pressurization is based on the rate of change of altitude in the
cabin, not the actual altitude.
If the pressurization were based on actual descent rate, and actually
started at 8,000 feet, you wouldn't like the results.
--
Jim Pennino
Remove .spam.sux to reply.
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| User: "tj Frazir" |
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| Title: Re: pressurized airplane cabins |
16 Aug 2005 10:29:57 PM |
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Tilt your head back and ywan .
It may equalise the presure in your ears.
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| User: "PD" |
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| Title: Re: pressurized airplane cabins |
18 Aug 2005 12:56:57 PM |
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wrote:
If the air in a passenger jet is pressurized to 10,000 feet or so, why
do my ears start to "pop" (or "un-pop") nearly as soon as the plane
starts its descent, still practically at it's cruising altitude of
30,000+ feet. I assume it has to do with the way the pressure is
maintained by the engines compressing outside air so any variation in
engine speed, plane speed, altitude would alter somewhat the cabin
pressure. Is the "pressurized to 10,000 feet" only true more or less?
How much variation is there in a normal flight?
Dave
It is only true more or less. Your ears are incredibly sensitive to
changes in pressure. My ears pop routinely when I climb a hill of 700
ft on my way home.
PD
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