Physics Help Forum Air plane pressure

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 Sep 26th 2018, 03:59 PM #1 Forum Admin     Join Date: Apr 2008 Location: On the dance floor, baby! Posts: 2,776 Air plane pressure So I'm flying on a jet and I have to swallow to reduce the pressure in my ears and a thought occurred to me. The jet is essentially a flying tube, sealed to maintain normal air pressure. But if it is sealed then how can the air pressure in the plane rise and fall? Thanks! -Dan __________________ Do not meddle in the affairs of dragons for you are crunchy and taste good with ketchup. See the forum rules here.
 Sep 26th 2018, 05:05 PM #2 Senior Member   Join Date: Jun 2010 Location: NC Posts: 417 My Guess! At altitude (~30,000ft) the ambient outside aircraft pressure is about 6psi. An air bleed from an engine compressor section to the craft interior pressurizes the in-flight cabin to about 10psi... About typical flight pressure. There is no "pressure of the ear." There is a pressure outside acting on the ear membrane (drum) via passage through the outer ear. Also a pressure acts interior to the ear membrane. This pressure path passes through the nose, mouth then sinus passages interior to the head. Upon a headache, when pressure one side of the drum differs from the other - blow your nose! Just my thoughts .... topsquark likes this.
Sep 26th 2018, 06:41 PM   #3
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Aircraft are not fully pressurised (to 15Psi) they want to keep the weight of the aircraft down ... just enough pressure to keep the passengers alive (12 to 11 psi ) with normal air , then the fuselage can be thin ...
If they had pure oxygen the fuselage could be even thinner .... astronauts live in 5psi pure oxygen.

 Originally Posted by THERMO Spoken Here At altitude (~30,000ft) the ambient outside aircraft pressure is about 6psi. There is no "pressure of the ear." There is a pressure outside acting on the ear membrane (drum) ....
30,000ft =4.36 psi ....

I think it's true to say there is (over) pressure in the (inner) ear ...outside pressure is reduce , ear drum is pushed outwards when aircraft ascends ... pushed inwards when aircraft descends .

Last edited by oz93666; Sep 26th 2018 at 06:44 PM.

Sep 29th 2018, 09:18 AM   #4
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 Originally Posted by topsquark So I'm flying on a jet and I have to swallow to reduce the pressure in my ears and a thought occurred to me. The jet is essentially a flying tube, sealed to maintain normal air pressure. But if it is sealed then how can the air pressure in the plane rise and fall? Thanks! -Dan
There are other ways to normalize ear pressure. Just yawn with your mouth closed.

 Sep 29th 2018, 05:10 PM #5 Banned   Join Date: Mar 2018 Location: Xinhui Guangdong Province China Posts: 118 gravity Just imagine what's the reaction of the atmosphere if gravity of the earth vibrates... topsquark likes this.

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