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Do The Triangular Inlets Under 747 Serve A Purpose?  
User currently offlineHighFlyer9790 From United States of America, joined Jul 2005, 1241 posts, RR: 0
Posted (9 years 5 months 2 weeks 2 days 21 hours ago) and read 5083 times:

Does anyone know whether the triangular shaped inlets on the underbelly of all 747s serve a purpose? In the photo you can clearly see the 3 of them in front of the under carriage and by the leading edge

http://images.airliners.net/open.fil...r=21&prev_id=622768&next_id=573962

apologies if some of earlier posts had already been discussed in detail...

regards


121
22 replies: All unread, jump to last
 
User currently offlineCitationJet From United States of America, joined Mar 2003, 2468 posts, RR: 3
Reply 1, posted (9 years 5 months 2 weeks 2 days 21 hours ago) and read 5048 times:

Based on what I learned from a previous thread, they are ram air intakes for cooling the heat exchangers for the air conditioning packs.

http://www.airliners.net/discussions/tech_ops/read.main/62453/4/
Reply #8.

.



Boeing Flown: 701,702,703;717;720;721,722;731,732,733,734,735,737,738,739;741,742,743,744,747SP;752,753;762,763;772,773.
User currently offlinePhilSquares From , joined Dec 1969, posts, RR:
Reply 2, posted (9 years 5 months 2 weeks 2 days 21 hours ago) and read 5007 times:

They are the inlets for the air conditioning packs. If you look further aft, to about 3 feet prior to the body gear doors you will see the exit doors, they're louvered and will automatically position, just like the inlet doors.

User currently offlineVirginFlyer From New Zealand, joined Sep 2000, 4575 posts, RR: 41
Reply 3, posted (9 years 5 months 2 weeks 1 day 23 hours ago) and read 4800 times:

HighFlyer9790 - Welcome to Airliners.net. A few quick asides for you:

1)You can display an airliners.net picture using the following code:

[photoid:608498], but replaicing '[' and ']' with '<' and '>':


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Click here for bigger photo!

Photo © Stuart Lawson



2) These sort of technical questions are probably better asked in the Tech/Ops Forum.

3) Please be descriptive with your titles - it helps everyone get an idea of what your thread is about.

Once again, welcome, and I hope you enjoy all this site has to offer!

V/F



"So powerful is the light of unity that it can illuminate the whole earth." - Bahá'u'lláh
User currently offlineFlyinTLow From Germany, joined Oct 2004, 525 posts, RR: 0
Reply 4, posted (9 years 5 months 2 weeks 1 day 22 hours ago) and read 4736 times:

Yes, air inlets for the a/c. And as mentioned before the outlets are about 10 feet behind that (rather brown in that picture). A very good spot to stand about another 10 feet down the fuselage in the winter when it is cold, cause a lot of hot air comes out there. Not too fancy if it's hot on the tarmac already  Smile

Cheers,
T-Low



- When dreams take flight, follow them -
User currently offlineDeltaGuy From , joined Dec 1969, posts, RR:
Reply 5, posted (9 years 5 months 2 weeks 1 day 22 hours ago) and read 4661 times:

They're also excellent for drying off your rain gear when it stops raining on the ramp. Those packs do make alot of noise though.

DeltaGuy


User currently offlineHAWK21M From India, joined Jan 2001, 31702 posts, RR: 56
Reply 6, posted (9 years 5 months 2 weeks 1 day 20 hours ago) and read 4575 times:

Ram Air Inlets for the Air Conditioning System.

Quoting DeltaGuy (Reply 5):
They're also excellent for drying off your rain gear when it stops raining on the ramp

The Exhaust Louvers are Excellent Dryers. {bigthumbsup

regds
MEL



Think of the brighter side!
User currently offlineStarlionblue From Greenland, joined Feb 2004, 17172 posts, RR: 66
Reply 7, posted (9 years 5 months 2 weeks 1 day 20 hours ago) and read 4527 times:

Quoting HighFlyer9790 (Thread starter):
Does anyone know whether the triangular shaped inlets on the underbelly of all 747s serve a purpose?

Totally useless and purely decorative Big grin Sorry your title gave me a laugh but it was a good question.



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineIkramerica From United States of America, joined May 2005, 21580 posts, RR: 59
Reply 8, posted (9 years 5 months 2 weeks 1 day 17 hours ago) and read 4387 times:

Yeah, A and B like to design lots of useless holes into their fuselages. Makes for a greater engineering challenge. And if you don't challenge the engineers, how will they ever learn?


Of all the things to worry about... the Wookie has no pants.
User currently offlineOzLAME From Australia, joined Feb 2005, 338 posts, RR: 0
Reply 9, posted (9 years 5 months 2 weeks 1 day 11 hours ago) and read 4217 times:

These inlets are not quite triangular, they are more a sort of teardrop shape that has the bottom cut off. The generic name for inlets of this shape is NACA Duct, after the National Advisory Commitee for Aeronautics (forerunner to NASA) that came up with the shape. The shape means that drag associated with the opening is minimal; these ducts can be very large, as on the 747, or very small, e.g. an inlet on an engine nacelle. They can be found on all sorts of different aircraft; you can see a NACA Duct on the a/c shown below, forward of the door and below the windscreen.

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Photo © Maartenw




Monty Python's Flying Circus has nothing to do with aviation, except perhaps for Management personnel.
User currently offlineCX flyboy From Hong Kong, joined Dec 1999, 6638 posts, RR: 55
Reply 10, posted (9 years 5 months 2 weeks 1 day 7 hours ago) and read 4032 times:

They serve a purpose? I thought they looked pretty. Is that not a good enough reason these days?

User currently offlineAreopagus From United States of America, joined Sep 2001, 1373 posts, RR: 1
Reply 11, posted (9 years 5 months 2 weeks 1 day 6 hours ago) and read 3931 times:

The NACA duct was used for the engine air inlets for the North American Aviation F-93, a development of the F-86. See, for example, Wikipedia, but note that their overhead view shows a more conventional inlet that was tried after the NACA inlet turned out not to supply enough air for the engine.

(Edited for typo)

[Edited 2005-07-08 18:48:53]

User currently offlineStarlionblue From Greenland, joined Feb 2004, 17172 posts, RR: 66
Reply 12, posted (9 years 5 months 2 weeks 1 day 2 hours ago) and read 3772 times:

Quoting CX flyboy (Reply 10):
They serve a purpose? I thought they looked pretty. Is that not a good enough reason these days?

Only if the plane has a nice livery and is washed regularly Big grin



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineVSIVARIES From United Kingdom, joined Aug 2004, 108 posts, RR: 4
Reply 13, posted (9 years 5 months 2 weeks 1 day 2 hours ago) and read 3721 times:

Air to Air missile hatches - a new system employed by VS. It's meant to be confidential.  shhh  These must have opened by accident.


For every action there is always an unequal but mostly similar reaction.
User currently offlineMD11Engineer From Germany, joined Oct 2003, 14139 posts, RR: 62
Reply 14, posted (9 years 5 months 2 weeks 1 day ago) and read 3643 times:

Chemtrail dispensers Big grin

Jan


User currently offlineAeroWeanie From United States of America, joined Dec 2004, 1610 posts, RR: 52
Reply 15, posted (9 years 5 months 1 week 4 days 19 hours ago) and read 3357 times:
Support Airliners.net - become a First Class Member!

Quoting OzLAME (Reply 9):
These inlets are not quite triangular, they are more a sort of teardrop shape that has the bottom cut off. The generic name for inlets of this shape is NACA Duct, after the National Advisory Commitee for Aeronautics (forerunner to NASA) that came up with the shape.

They are NACA Inlets, not NACA ducts. Ducts carry air from one place to another. Inlets allow air to flow into a body. They are unique inlets in that they are semi-submerged and still have reasonable, though not great, pressure recovery.


User currently offlineHAWK21M From India, joined Jan 2001, 31702 posts, RR: 56
Reply 16, posted (9 years 5 months 1 week 3 days 12 hours ago) and read 3209 times:


View Large View Medium
Click here for bigger photo!

Photo © Stuart Lawson


Why Three Inlets.Are there Three Packs.Explain the Outboard LH one.
regds
MEL



Think of the brighter side!
User currently offlineMD11Engineer From Germany, joined Oct 2003, 14139 posts, RR: 62
Reply 17, posted (9 years 5 months 1 week 3 days 9 hours ago) and read 3186 times:

Yes, three packs on the 747

Jan


User currently offlineHAWK21M From India, joined Jan 2001, 31702 posts, RR: 56
Reply 18, posted (9 years 5 months 1 week 3 days 9 hours ago) and read 3180 times:

Quoting MD11Engineer (Reply 17):
Yes, three packs on the 747

Interesting.
What are the Reffered to as Left pack,Right Pack & Centre pack.
regds
MEL



Think of the brighter side!
User currently offlineAir2gxs From , joined Dec 1969, posts, RR:
Reply 19, posted (9 years 5 months 1 week 3 days 9 hours ago) and read 3181 times:

Quoting HAWK21M (Reply 16):
Why Three Inlets.Are there Three Packs.Explain the Outboard LH one.

As far as I know, all pax operators have 3 packs. Some cargo operators have de-activated and removed the #2 pack for weight and cost savings.


User currently offlineNZ1 From Australia, joined May 2004, 2272 posts, RR: 25
Reply 20, posted (9 years 5 months 1 week 1 day 20 hours ago) and read 3020 times:
AIRLINERS.NET CREW
FORUM MODERATOR

Quoting HAWK21M (Reply 18):
What are the Reffered to as Left pack,Right Pack & Centre pack

Pack 1, 2 and 3. Not L, C and R.

NZ1


User currently offlineHAWK21M From India, joined Jan 2001, 31702 posts, RR: 56
Reply 21, posted (9 years 5 months 1 week 1 day 17 hours ago) and read 3010 times:

Quoting NZ1 (Reply 20):
Pack 1, 2 and 3

Thanks.
And how is the Distribution to the Upper deck on Pax version.How many Zones 3 or more.
regds
MEL



Think of the brighter side!
User currently offlineAbhi From Canada, joined Oct 2001, 54 posts, RR: 0
Reply 22, posted (9 years 5 months 1 week 1 day 15 hours ago) and read 3008 times:

You can feel the heat from those outlets when you're working the loader in the aft belly. It feels great in the winter but in the summer I tried working the front belly as much as possible.

Funny thing happened to one of the guys one day. He was bringing a stroller from the gate to put in the bulk load and his hat got sucked into the inlet. This happened on the 340 where you can actually see inside the inlet. They're too high on the 747.

Maintenance had to remove the entire panel to get that hat out. They were quick though: delayed the flight only fifteen minutes.


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