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What Are These Vents Called?  
User currently offlineAC320tech From Canada, joined Jul 2006, 197 posts, RR: 1
Posted (5 years 9 months 7 hours ago) and read 4768 times:

It's been puzzling me for a while, I was told (at least on the Airbuses) that this vent has something to do with the fuel tanks.

Take a look in this picture, if you look at the watermark on the photo, the letter 'R' is right where the V-shaped vent is.


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Photo © Wu Weiqiang



If you look at this photo, follow the inside edge of the aileron forward, and you can kind of see it, looks like a dent in the wing next to the small vane.


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Photo © John R. Beckman



It also appears on the L1011, on the right side. In this photo, the two V-shaped (more like > shaped since it is on the side) vents are below the pitot tubes.


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Photo © John Gregory



What are these vents called? And more importantly, what are they used for?

10 replies: All unread, jump to last
 
User currently offlinePGNCS From United States of America, joined Apr 2007, 2828 posts, RR: 45
Reply 1, posted (5 years 9 months 7 hours ago) and read 4749 times:

These vents are not equivalent. The vents on the wing undersides are fuel tank vents; the openings on the L-1011 are the inlets for the air conditioning pack cooling. The cooling air is subsequently vented overboard through the louvers you see behind the openings on the L-1011.

User currently offlineFlyf15 From , joined Dec 1969, posts, RR:
Reply 2, posted (5 years 9 months 5 hours ago) and read 4705 times:

That shape is called a NACA Inlet... it is used for varied reasons on varied aircraft (and non-aircraft) applications. It is popular because it is simple and creates very low drag.

http://en.wikipedia.org/wiki/NACA_duct


User currently offlineJetMech From Australia, joined Mar 2006, 2699 posts, RR: 53
Reply 3, posted (5 years 9 months 5 hours ago) and read 4681 times:



Quoting AC320tech (Thread starter):
I was told (at least on the Airbuses) that this vent has something to do with the fuel tanks.



Quoting PGNCS (Reply 1):
The vents on the wing undersides are fuel tank vents;

I think that vent is used to pressurise the fuel tanks during flight, as well as removing accumulated fuel fumes.

Regards, JetMech



JetMech split the back of his pants. He can feel the wind in his hair.
User currently offlineHAWK21M From India, joined Jan 2001, 31684 posts, RR: 56
Reply 4, posted (5 years 9 months 4 hours ago) and read 4663 times:

The vent below the wing on the Airbus pic seem to be fuel tank vents.
On The L1011 pic those look like Ram air Inlets.
regds
MEL



Think of the brighter side!
User currently offlineCosmicCruiser From United States of America, joined Feb 2005, 2255 posts, RR: 15
Reply 5, posted (5 years 9 months 4 hours ago) and read 4652 times:

The V-shaped vents on the 1011 look like pack cooling doors. They look the same on the DC-10 & MD-11. There's another one one the other side.

User currently offlineAC320tech From Canada, joined Jul 2006, 197 posts, RR: 1
Reply 6, posted (5 years 9 months 4 hours ago) and read 4635 times:



Quoting CosmicCruiser (Reply 5):
The V-shaped vents on the 1011 look like pack cooling doors. They look the same on the DC-10 & MD-11. There's another one one the other side.

Yeah that's what I was wondering too, because the air con system's risers are right in that area on the DC10 and MD11.

Thanks for the replies guys, now I can sleep at night. Ha!


User currently offlineEMBQA From United States of America, joined Oct 2003, 9364 posts, RR: 11
Reply 7, posted (5 years 8 months 4 weeks 1 day 17 hours ago) and read 4481 times:



Quoting AC320tech (Thread starter):
I was told (at least on the Airbuses) that this vent has something to do with the fuel tanks.

First. it's really an inlet...not a vent. When used with fuel tanks it allows air to enter the tanks and provide a positive pressure into the surge tank. When used with ACM intakes it provides a smooth airflow into the compressor. The V shaped inlet is still called a NACA Duct....... It's just how its used.



"It's not the size of the dog in the fight, but the size of the fight in the dog"
User currently offlineTdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 8, posted (5 years 8 months 4 weeks 1 day 12 hours ago) and read 4377 times:



Quoting EMBQA (Reply 7):
Quoting AC320tech (Thread starter):
I was told (at least on the Airbuses) that this vent has something to do with the fuel tanks.

First. it's really an inlet...not a vent. When used with fuel tanks it allows air to enter the tanks and provide a positive pressure into the surge tank.

It's both. During level flight, it provides a slight positive pressure to the tanks and lets air in to replace burned fuel (extremely small flow rate, it's really more of a pressure port). However, during a climb the pressure lapse rate is far higher than the fuel consumption rate, so it's actually a pretty significant vent, otherwise you'd overpressure the wing on climbout. Also, during fueling, it's a vent since the air has to leave to make room for the fuel.

During descent it reverses and that's the only time it's really behaving like an inlet, since you need to repressurize the wing during descent.

Tom.


User currently offlineTristarSteve From Sweden, joined Nov 2005, 4014 posts, RR: 34
Reply 9, posted (5 years 8 months 4 weeks 1 day 10 hours ago) and read 4339 times:



Quoting Tdscanuck (Reply 8):
Also, during fueling, it's a vent since the air has to leave to make room for the fuel.

And if you see fuel coming out you have a problem!
The vents are part of small (normally) empty tanks at the wingtips. If during refuelling the tank high level shut off does not work, then the fuel goes through the vent system, and fills up the vent/surge tank. If there is space in the wing tanks, this fuel will drain back in, but more normally it pours out of the vents. On most aircraft, when you stop the refuelling, the overflow stops, but on a B744, because the wing tips hang down when the tanks are full, the fuel continues to syphon its way out and doesn't stop very quickly. You can sometimes see it coming out of here during the taxy. The B744 sways sideways, and fuel is spilled into the tank and drains out.
But must admit it is not that common. Hasn't happened to me for a few years.


User currently offlineHAWK21M From India, joined Jan 2001, 31684 posts, RR: 56
Reply 10, posted (5 years 8 months 4 weeks 1 day 3 hours ago) and read 4223 times:



Quoting TristarSteve (Reply 9):
The vents are part of small (normally) empty tanks at the wingtips.

The term used normally is 'surge tank" on the B737/757.
regds
MEL



Think of the brighter side!
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