Mr Spaceman
Topic Author
Posts: 2723
Joined: Thu Mar 15, 2001 5:09 am

Huge Tube Inside 747's Belly?

Sat Nov 27, 2004 4:35 am

Hi guys.

The photographer of this photo asks ........

"There is a huge tube in there, anybody know what it's for?"

I'd like to know the answer too.

Actually, there are 2 metal tubes that can be seen inside this KLM 747-206's belly. One's close to the wing root and the other huge one is deep inside under the middle of the cargo hold floor.

What are these tubes used for?

For the fun of it, I'll take a guess. They're both used for the 747's Environmental Control System. The smaller tube supplies hot bleed air from engines #3 and #4 to the Air Conditioning Pack's Heat Exchangers and Air Cycle Machines (these 3 A/C packs are located near the main landing gear bays). The air then flows from the A/C packs (at cabin air temperature) via the huge tube in the belly and is then transported via ducts to all the overhead air vents in the passenger cabin, cockpit, & cargo hold, where it's used to pressurize the aircraft and control air temperature.

That's just a guess ....am I close?  Laugh out loud


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Photo © Tim de Groot - AirTeamImages



Chris  Smile
"Just a minute while I re-invent myself"
 
miamiair
Posts: 4249
Joined: Thu Jul 15, 2004 9:42 pm

RE: Huge Tube Inside 747's Belly?

Sat Nov 27, 2004 6:30 am

Let's not forget that the bleed air from the APU has to make its way forward from the tail also...

[Edited 2004-11-26 22:30:58]
Molon Labe - Proud member of SMASH
 
QantasA332
Posts: 1473
Joined: Sat Dec 13, 2003 5:47 pm

RE: Huge Tube Inside 747's Belly?

Sat Nov 27, 2004 6:58 am

The larger tube which is further into the aircraft is most likely an air conditioning pack or part of that general sub-system. As for the small pipe, I'm pretty sure it's an engine bleed-air duct...

Cheers,
QantasA332
 
242
Posts: 495
Joined: Tue Oct 24, 2000 1:10 pm

RE: Huge Tube Inside 747's Belly?

Sat Nov 27, 2004 7:44 am

The smaller tube is bleed air, the tubing starts out silver/grey when new and turns a bluish color with heat.

The larger tube is likely a pack heat exchanger air inlet duct.
 
747NUT
Posts: 77
Joined: Sun Sep 05, 2004 12:24 am

RE: Huge Tube Inside 747's Belly?

Sat Nov 27, 2004 1:32 pm

The smaller of the two tubes is the pneumatic ducting that comes from the #3 & 4 engines (there is also one on the opposite wing for the # 1 & 2 )
The larger duct is the ram air cooling for the airconditioning heat exchangers, you can't see the intake on that photo but you can see it on this one.

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Photo © Benjamin Freer



Regards Mike
If it's not broken, don't fix it !
 
Mr Spaceman
Topic Author
Posts: 2723
Joined: Thu Mar 15, 2001 5:09 am

RE: Huge Tube Inside 747's Belly?

Sat Nov 27, 2004 2:30 pm

Hi guys.

OK, so those tubes do provide engine bleed air for the 747's pneumatic system and the environmental control system..... I was close enough! Big grin Thank You, Thank You, no applause please .... just throw money!!!  Laugh out loud

It's kinda neat to see inside the guts of a 747's belly.


Chris  Smile
"Just a minute while I re-invent myself"
 
aviopic
Posts: 2423
Joined: Sat Mar 13, 2004 7:52 pm

RE: Huge Tube Inside 747's Belly?

Sun Nov 28, 2004 4:03 am

Especially for you made another image today to clear up this issue.



The big one is the ram air intake and the smaller one which Tim referred too is the bleed air supply.
The truth lives in one’s mind, it doesn’t really exist
 
efohdee
Posts: 212
Joined: Fri Oct 29, 2004 4:52 am

RE: Huge Tube Inside 747's Belly?

Mon Nov 29, 2004 5:47 am

Large intestines!!!
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