Mr.BA
Topic Author
Posts: 3310
Joined: Sun Sep 24, 2000 12:26 pm

Wing Of The B747-400

Tue Oct 09, 2001 1:56 pm

Hi everyone,

I noticed that the wing of the B744, near winglet bents down.

For example in these pictures the rest of the wings are blending upwards except for the last part near the winglet.


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Photo © Graham Hitchen



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Photo © Jason Milligan



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Photo © Bo Kim



Are there any reason to it or is it just the weight of the winglet that is pulling it downwards?

Thanks

alvin
Boeing747 万岁!
 
travellin'man
Posts: 469
Joined: Sun May 13, 2001 1:55 am

RE: Wing Of The B747-400

Tue Oct 09, 2001 2:47 pm

Not being either a pilot or an aerodynamicist, I can't give you a definitive answer. I can vaguely say that the wings bend during flight as a function of lift. It is very obvious on an A340, where the wing bends upwards on take-off as the plane achieves lift; quite fun to watch.
try on the tech ops page, and I'm sure you can get someone to explain the exact physics of it.
It is not enough to be rude; one must also be incorrect.
 
boeingmd82
Posts: 231
Joined: Thu Jun 21, 2001 11:14 am

RE: Wing Of The B747-400

Tue Oct 09, 2001 3:09 pm

The reason the -400 wing seems to bend down before takeoff is because when the wing is fully fueled the wing tips droop slightly with the weight of the fuel.

It's pretty strange, and it adds a few feet to the 747's already impressive wingspan.

BMD82
 
AJ
Posts: 2295
Joined: Wed Nov 03, 1999 3:54 pm

RE: Wing Of The B747-400

Tue Oct 09, 2001 3:12 pm

Alvin,
I have noticed that trailing edge 'bend' near the winglet both on the ground and in the air, so it can't be due to aerodynamic loads. Mr. Boeing must have put it there due to localised airflows I guess.
 
UTA_flyinghigh
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Joined: Wed Oct 03, 2001 8:46 pm

RE: Wing Of The B747-400

Tue Oct 09, 2001 3:29 pm

Wings of the 744 can bend down before a long flight because the wing is fully loaded with fuel, i.e the UA 744 pictured above. Just after takeoff, the tremendous lift provided by the wings causes them to bend upwards, like the QF 744. This is absolutely normal as aircraft wings are designed to be flexible. In fact all large-wingspan aircraft tend to do this  Smile/happy/getting dizzy
Fly to live, live to fly - Air France/KLM Flying Blue Platinum, BMI Diamond Club Gold, Emirates Skywards
 
Mr.BA
Topic Author
Posts: 3310
Joined: Sun Sep 24, 2000 12:26 pm

RE: Wing Of The B747-400

Tue Oct 09, 2001 3:49 pm

I agree the wings bend down because of fuel in the wings... I thought the whole wing would blend up during take-off. But what's amazing to me that I have noticed, the wing blends upwards in flight to provide lift the end of the wing near the winglet, blends down.

But hey, whatever it is, that's a great wing being able to carry tons over miles.  Smile

alvin
Boeing747 万岁!
 
Guest

RE: Wing Of The B747-400

Tue Oct 09, 2001 8:25 pm

I dont believe that the fuel in the wings causes the area around the wingtip to droop down. Look at the Virgin shot. The area around the winglet droops down yes, but it is on approach, so I would gather that that fuel tank is going to be empty pretty soon.

-Regards, VA
 
RAAFController
Posts: 124
Joined: Wed May 30, 2001 9:50 am

RE: Wing Of The B747-400

Tue Oct 09, 2001 9:23 pm

The wing on the B744 were redesigned totally by Boeing to be made of different materials and have different aerodynamic performance over the 747 classics. It was not simply a case of adding wingtips to the old 747 wing. In doing this, Boeing delibarately altered the angle of the chord line at the ends of the wings. This was designed to reduce wingtip vortecies and make the wing more efficient. It has an added effect of reducing the likeliness of 'dutch roll'.

The wings may flex and droop due to fuel, but the downward angle at the tips is a design feature.

I don't have any more info, but i'm sure if you try the Tech ops page someone will help out. Most likely even correct the above!  Smile/happy/getting dizzy (and feel free to, i only rememebr reading the above somewhere and am no expert!)

Dave
 
VS744
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RE: Wing Of The B747-400

Tue Oct 09, 2001 9:46 pm

I also noticed this, when on the ground, I could quite clearly see the wingtip from the middle isle out of the window, but during flight, the wing had moved at least 10-15 feet upwards and I could not see the tip any longer.

I came to the conclusion that it was to do with the weight of the aircraft acting as a pulling force at the centre, and dont think it had much to do with fuel load as on landing, the wing returned to the exact same position (with no fuel).
 
Mr.BA
Topic Author
Posts: 3310
Joined: Sun Sep 24, 2000 12:26 pm

RE: Wing Of The B747-400

Wed Oct 10, 2001 10:57 am

Thanks everyone  Smile

alvin
Boeing747 万岁!

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