ANITIX87
Topic Author
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747 Landing - Wing Mechanics

Tue Jan 02, 2007 3:33 am

Hey, guys.

Saw this video.
http://flightlevel350.com/Aircraft_B...Lufthansa_Aviation_Video-7608.html

When the 744 lands, the inboard forward slats retract underneath the wing, just after the thrust reverse deploys.

I've never noticed this before.

What purpose does it serve, is it automatic, and is this the way those slats usually store themselves, or is a different motion? (I was under the impression that they slide back into place, not pivot around the wing).

Thanks a bunch.

TIS
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jamesbuk
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RE: 747 Landing - Wing Mechanics

Tue Jan 02, 2007 3:38 am

Im guessing here,

1) incase stones or other FOD gets thrown up, dont want it going in there and cutting hydraulic lines.

2) Reduce the lift the wing is making, you want the least lift in landing, so you can stop easier.

Rgds --James--
You cant have your cake and eat it... What the hells the point in having it then!!!
 
Tristarsteve
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RE: 747 Landing - Wing Mechanics

Tue Jan 02, 2007 4:41 am

They retract when thrust reverse deployed for FOD.
Look in the index, this topic comes up every six months!

The B747 has leading edge flaps, not slats like most other aircraft.
 
Marquis
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Joined: Sat Sep 10, 2005 5:35 am

RE: 747 Landing - Wing Mechanics

Tue Jan 02, 2007 6:18 am

Quoting Tristarsteve (Reply 2):
The B747 has leading edge flaps, not slats like most other aircraft.

Correct. Also referred as "Krueger Flaps" or "Drooping Flaps".

Here are some good examples of the different leading edge devices:

Boeing 747 (drooping from the lower wing surface):

Clean config.:

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Click here for bigger photo!

Photo © Will Lanting



Fully deployed:

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Click here for bigger photo!

Photo © Will Lanting



Boeing 767 and various other aircraft (slat type; extending forward from the upper wing surface):


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Photo © Rafael k - Art on Airports

Riding the radials...
 
Tristarsteve
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RE: 747 Landing - Wing Mechanics

Tue Jan 02, 2007 7:57 am

Quoting Marquis (Reply 3):
"Drooping Flaps".

Not to be confused with the leading edge droop on the Trident 1C.
This was a very efficient lift device, as was proved by the crash in Staines of RPI when they were inadvertantly retracted.
When I was young I used to help rig these terrors, it was a never ending job!. Every time you got one clearance right, another one went out.
Later Tridents had slats.
 
AJ
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RE: 747 Landing - Wing Mechanics

Tue Jan 02, 2007 8:56 am

The 747's leading edge flaps are beautiful to watch, however once I observed them being extended in a quiet hangar and the noise they made was somewhat offputting. Bending fibreglass etc. Lucky they normally run with the engines running!

After watching this 747 land at HND I was amazed that the broken flap just outboard of #3 still folded away neatly...I just hope it was noticed as the flaps were retracted when it arrived at the gate.


View Large View Medium
Click here for bigger photo!

Photo © Anthony Jackson

 
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jetmech
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RE: 747 Landing - Wing Mechanics

Tue Jan 02, 2007 9:31 am

Quoting TristarSteve (Reply 4):
When I was young I used to help rig these terrors, it was a never ending job!. Every time you got one clearance right, another one went out.
Later Tridents had slats.

Rigging the 747 Variable Camber Leading Edge (VCLE) flaps could result in much colourful language as well. Each pneumatic air motor unit drove a group flaps by it self. These were connected in series. The problem was that once you had the individual VCLE flaps in perfect rig and reattached the drive shafts, the fibreglass panels would straighten out and take all the slop out of the drive mechanism. This would instantly put the flap out of rig.

The trick was to rig the flaps slightly beyond the rig position by what you guessed was the amount of slop in the drive mechanism. If you got it right, the panel would straighten out and hopefully take out just enough slop to get you in rig. Unfortunately, it often took many "guesses" to get it right, and this had to be done at both ends of each individual panel.

Quoting AJ (Reply 5):
I observed them being extended in a quiet hangar and the noise they made was somewhat offputting. Bending fibreglass etc. Lucky they normally run with the engines running!

You would be surprised at how stiff those panels actually were. We had these panels off many times for repairs and even if I used both arms and my foot for leverage, I could never get the panel to flex more than a few centimetres.

Quoting AJ (Reply 5):
After watching this 747 land at HND I was amazed that the broken flap just outboard of #3 still folded away neatly...I just hope it was noticed as the flaps were retracted when it arrived at the gate.

The broken part in that photo is the bull nose leading edge of the VCLE. This is a separate element from the VCLE fibreglass panel, and is made from aluminium alloy. Very nice photo BTW  bigthumbsup !

Regards, JetMech
JetMech split the back of his pants. He can feel the wind in his hair :shock: .
 
AJ
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RE: 747 Landing - Wing Mechanics

Wed Jan 03, 2007 1:37 pm

Quoting JetMech (Reply 6):
Very nice photo BTW !

Thanks very much!
 
highflyer9790
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RE: 747 Landing - Wing Mechanics

Fri Jan 05, 2007 10:47 am

why would the slats come our again if the flaps will just retract anyway?
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