UAL747
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Why Does The 744 Wing Curve Down At The Ends?

Thu Jun 12, 2003 1:08 pm

I didn't realize this until I took my first trip on the 744. The wings curve downward at the last few feet on each wing. Also, if you notice sitting in front of the wing, the last 10-20 feet of the leading edges have a different angle than the rest of the wing. What are the purposes of these features?

Wingtip Bent Downward

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Leading Edge

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UAL747
"Bangkok Tower, United 890 Heavy. Bangkok Tower, United 890 Heavy.....Okay, fine, we'll just turn 190 and Visual Our Way
 
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HA_DC9
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RE: Why Does The 744 Wing Curve Down At The Ends?

Thu Jun 12, 2003 1:11 pm

They curve down because of the weight of the fuel in the wing.
 
MSYtristar
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RE: Why Does The 744 Wing Curve Down At The Ends?

Thu Jun 12, 2003 1:12 pm

Just a guess here: Would it have something to do with the heavy fuel load on the aircraft?


 
as739x
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RE: Why Does The 744 Wing Curve Down At The Ends?

Thu Jun 12, 2003 1:13 pm

Its called fuel, and weights 6.7 lbs/per gallon if Im not mistaken. Anything that has flex in when producing lift as in the wing will have flex the other way when not producing lift.
ASSFO
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Big777jet
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RE: Why Does The 744 Wing Curve Down At The Ends?

Thu Jun 12, 2003 1:16 pm

AS729X~

You are correct. 6.7 lb per gal of kerosene fuel.


Big777jet

 
JBirdAV8r
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RE: Why Does The 744 Wing Curve Down At The Ends?

Thu Jun 12, 2003 1:17 pm

If I recall, isn't this part of the reason the B-52 has those outrigger wheels on the ends of the wings?
I got my head checked--by a jumbo jet
 
UAL747
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RE: Why Does The 744 Wing Curve Down At The Ends?

Thu Jun 12, 2003 1:24 pm

I'm not talking about the entire wing flexing due to fuel. I know that the entire wing will flex because of the weight of fuel. I'm talking about how the very tip of the wing, close to the winglet has an extra downward bend to it. Even when the wing flexes upward during flight, there is a bend in the tips.


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UAL747
"Bangkok Tower, United 890 Heavy. Bangkok Tower, United 890 Heavy.....Okay, fine, we'll just turn 190 and Visual Our Way
 
UAL747
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RE: Why Does The 744 Wing Curve Down At The Ends?

Thu Jun 12, 2003 1:26 pm

Also, when talking about the leading edge, I'm talking about how the wing is swept backward. The outer most parts of the wings past the #1 and #4 engines are swept back at a different angle.

UAL747
"Bangkok Tower, United 890 Heavy. Bangkok Tower, United 890 Heavy.....Okay, fine, we'll just turn 190 and Visual Our Way
 
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clickhappy
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RE: Why Does The 744 Wing Curve Down At The Ends?

Thu Jun 12, 2003 1:35 pm

move this to the Tech Forum!
 
wn700driver
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RE: Why Does The 744 Wing Curve Down At The Ends?

Thu Jun 12, 2003 1:38 pm

I would guess it has something to do with the fact that the outermost portion of the wing is actually an extension "tacked" onto the original wing design. IIRC, the -4XX 747s have an extra two metres of span (per wing), in addition to the winglets themselves.
To me, it appears that (in flight at least), that last outer portion is actually even (0 degrees to level), whereas the rest of the wing has a dihedral form, giving the illusion of a "droop."

That's my take on it anyway; and worth exactly what you paid for it,  Big grin
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ha763
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RE: Why Does The 744 Wing Curve Down At The Ends?

Thu Jun 12, 2003 2:32 pm

The droop at the end of the wing would have to do with the length of wings and the extra weight of the winglets.

The leading edge is a straight line. There is no change in angle. It is the wing flexing that makes it seem like the angle the wing is swept back is different at the area past the outer engine.


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n949wp
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RE: Why Does The 744 Wing Curve Down At The Ends?

Thu Jun 12, 2003 2:39 pm

The section of the wings outboard of the No. 1 and No. 4 engines do indeed have a slightly reduced sweepback angle. The purpose of that is to reduce wing flutter. I read about that in a book (forgot the name) that documents the development of the 747.

'949
 
DeltaMD11
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RE: Why Does The 744 Wing Curve Down At The Ends?

Thu Jun 12, 2003 7:47 pm

The wing droop at the end of each wing is the 6ft wing extension you're seeing that Boeing put on the -400's.

Bryan
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Mr.BA
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RE: Why Does The 744 Wing Curve Down At The Ends?

Thu Jun 12, 2003 9:02 pm

I'm pretty sure it's the weight of the winglets, nothing more...
Boeing747 万岁!
 
na
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RE: Why Does The 744 Wing Curve Down At The Ends?

Thu Jun 12, 2003 9:50 pm

Actually the degree of the leading edge angle of all the 747 wings is higher up to the outer engine joint. The reason is aerodynamics. I´m not a technician, but that´s for sure the reason for that. The A380 will be similar. The leading edge angle degree near the fuselage will be higher than on the outer parts.


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