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Bent Wing 747!  
User currently offlineGearup From Canada, joined Dec 2000, 578 posts, RR: 1
Posted (10 years 5 months 3 weeks 5 days ago) and read 8096 times:

Check out this photo by Oliver Brunke. I guess the downwards bend in the wings is due to the heavy fuel load, the a/c is headed to Hong Kong. Any comments on this?

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Photo © Oliver Brunke





I have no memory of this place.
45 replies: All unread, showing first 25:
 
User currently offlineBA From United States of America, joined May 2000, 11153 posts, RR: 59
Reply 1, posted (10 years 5 months 3 weeks 4 days 23 hours ago) and read 7988 times:

That's not unusual at all.

When the wings are full of fuel, they do bend downward. This happens on all aircraft. Some you will see it more noticable such as on the 747 because it has a big wing and carries a lot of fuel.

Nothing to worry about. Wings are made to flex. If they didn't, they'd snap all the time.

Regards



"Generosity is giving more than you can, and pride is taking less than you need." - Khalil Gibran
User currently offlineWilco From United States of America, joined Mar 2004, 355 posts, RR: 1
Reply 2, posted (10 years 5 months 3 weeks 4 days 23 hours ago) and read 7946 times:

the best part is when the heavies rotate and you can actually see the wing go from sagging to the exact opposite.


"Ever seen a grown man naked?"
User currently offlineQantasA332 From Australia, joined Dec 2003, 1500 posts, RR: 25
Reply 3, posted (10 years 5 months 3 weeks 4 days 23 hours ago) and read 7907 times:

Downward wing bending due to fuel-laden wings is actually structurally beneficial (while it lasts, of course). This is because it counteracts the large, upward wing bending present in flight, and thus lessens the strain on the wing.

Cheers,
QantasA332


User currently offlineWilco From United States of America, joined Mar 2004, 355 posts, RR: 1
Reply 4, posted (10 years 5 months 3 weeks 4 days 23 hours ago) and read 7835 times:

For you photonuts... it would be great to see:

a head-on shot of a 747 on the ground, fully loaded, wings bent downward
NEXT TO A PICTURE OF
a head-on shot off a 747 in the air, max lift, wings bent upward

This would be extraordinarily cooler if it was a similarly scaled photo (i.e. if you overlayed the two pics the fuselages matched in size)....

I'm probably asking way too much since a head-on air-to-air shot is so rare.



"Ever seen a grown man naked?"
User currently offlineKKMolokai From United States of America, joined Feb 2000, 760 posts, RR: 2
Reply 5, posted (10 years 5 months 3 weeks 4 days 23 hours ago) and read 7791 times:

Wow! That's freaky ... never noticed that before!!



We are the people of American Airlines. And we know why you fly.
User currently offlineAndrewuber From United States of America, joined Jul 2003, 2528 posts, RR: 40
Reply 6, posted (10 years 5 months 3 weeks 4 days 23 hours ago) and read 7688 times:

I flew on a United 744 from SFO-ORD, and I was amazed at the wing flex on takeoff. I was in business class, right on the leading edge, and it was cool watching that big wing bounce up and down on takeoff roll, then it seemed to curve up a good four or five feet when we rotated. Amazing!

I looked through the D/B, and found these pics:
Fully Loaded:

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Click here for bigger photo!

Photo © Carlos Borda


Empty, but on ground:

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Photo © Peter Unmuth - VAP


Flexing up while landing:

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Photo © Ryan C. Umphrey



I wonder exactly how much that wing flexes in "normal use". I've been on the Heavy tour at Everett, and they have pictures on the wall of a 747 wing in testing - it was bent probably 40 degrees up before it shattered!!

Drew



I'd rather shoot BAD_MOTIVE
User currently offlineKalakaua From United States of America, joined Jan 2004, 1516 posts, RR: 5
Reply 7, posted (10 years 5 months 3 weeks 4 days 23 hours ago) and read 7612 times:

This is most obvious on the Lockheed C-5 Galaxy. One may think it's wings are anhedral, when in fact, in flight they are cathedral. The wings droop down because of the weight of the fuel.

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Photo © JetPix




Gravity explains the motions of the planets, but it cannot explain who set the planets in motion.
User currently offlineAndz From South Africa, joined Feb 2004, 8451 posts, RR: 10
Reply 8, posted (10 years 5 months 3 weeks 4 days 20 hours ago) and read 7363 times:
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Actually I would hope that the wing flexes upwards BEFORE rotation, as that is a sign that lift is occurring and the damned thing will actually fly!



[Edited 2004-03-08 06:09:56]


After Monday and Tuesday even the calendar says WTF...
User currently offlineMr.BA From Singapore, joined Sep 2000, 3423 posts, RR: 22
Reply 9, posted (10 years 5 months 3 weeks 4 days 20 hours ago) and read 7345 times:

I've read before that when the B747 wings are fully fueled up it's not advisable to open the over-wing door. For you might not be able to close it again due to the weight of the wings hanging on the fuselage of the aircraft causing some distortion to it!


Boeing747 万岁!
User currently offlineCanadianNorth From Canada, joined Aug 2002, 3389 posts, RR: 9
Reply 10, posted (10 years 5 months 3 weeks 4 days 20 hours ago) and read 7287 times:

Quite amazing how much wings can bend before they give out... I suppose its alot smarter to have them flex like that otherwise when you get a decent load on there it would probably be down to one good bump and you'd be reaching for the rum while buddy there was saying a round of hail marys...




CanadianNorth



What could possibly go wrong?
User currently offlineAirbus_A340 From Hong Kong, joined Mar 2000, 1560 posts, RR: 19
Reply 11, posted (10 years 5 months 3 weeks 4 days 20 hours ago) and read 7270 times:

Hi there Kalakaua, thanks for pointing that out. I was taught that aircraft with anhedral wings are set as such to purposely de-stabalize the aircraft to help it turn as there is so much weight. These sort of aircraft have anhedral as opposed to dihedral because it would be impractical as it would be extremely hard to manouver with!

Airbus_A340



People. They make an airline. www.cathaypacific.com
User currently offlineVC-10 From United Kingdom, joined Oct 1999, 3701 posts, RR: 34
Reply 12, posted (10 years 5 months 3 weeks 4 days 12 hours ago) and read 6931 times:
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This is the VC10 structral test airframe undergoing a proof load test - equivalent to 2.5 G manoevre @ 296,000lbs, 1,000 Ft altitude and 330 Knts. The Wip tip deflection is over 8 Ft.

[Edited 2004-03-08 14:46:41]

User currently offlineFredT From United Kingdom, joined Feb 2002, 2185 posts, RR: 26
Reply 13, posted (10 years 5 months 3 weeks 4 days 7 hours ago) and read 6768 times:

The C5 has anhedral to counter the lateral stability inherent in high wing designs. "Cathedral"? Perhaps you're looking for "dihedral"?

Andz,
the wings will not flex before they are generating lift. They will not generate lift until they are at an angle of attack, and they're not at much of an angle of attack until rotation. Alas, no wing bending until rotation, and no vortices either which is beneficial if you are in a light and want to use the runway after a heavy.

Cheers,
Fred



I thought I was doing good trying to avoid those airport hotels... and look at me now.
User currently offlineKalakaua From United States of America, joined Jan 2004, 1516 posts, RR: 5
Reply 14, posted (10 years 5 months 3 weeks 4 days ago) and read 6536 times:

It can be called "cathderal" as well.


Gravity explains the motions of the planets, but it cannot explain who set the planets in motion.
User currently offlineTheflcowboy From United States of America, joined Jan 2004, 405 posts, RR: 0
Reply 15, posted (10 years 5 months 3 weeks 3 days 23 hours ago) and read 6514 times:

I saw a thing on some TV show, I think it was TLC, that the 747 wing can bend 26 feet up and down from whatever they deem to be the center. And then when it breaks, it breaks outside of the inner engine so that if it ever did, you would still have 3 working engines.


A318, A320, A332, A333, B1900, B722, B732, B733, B734, B735, B737, B738, B772, CR1, CR2, CR7, CR9, MD80, MD81, MD82, MD8
User currently offlineLiamksa From Australia, joined Oct 2001, 308 posts, RR: 0
Reply 16, posted (10 years 5 months 3 weeks 3 days 22 hours ago) and read 6474 times:

I've heard the wingspan of the B744 grows with a full fuel load due to the droop of the wings and angle of the winglets. Anyone know if this is true?

Wing bending moments:

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Photo © Joe Pries - A.T. TEAM
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Photo © Chris Sheldon



User currently offlineAJ From Australia, joined Nov 1999, 2389 posts, RR: 24
Reply 17, posted (10 years 5 months 3 weeks 3 days 22 hours ago) and read 6460 times:

Liamska, that is true due to the mounting angle of the winglets, as the wings bend down the winglets splay outwards.

Conducting the walkaround on the -400 gave a good indication of the bending. When lightly fuelled (30,000kg was the min fuel for dispatch) it was hard to see in to engines 1 and 4, but fully fuelled they were easy to inspect!

Re the C-5....it has anhedral designed into it that remains in flight.


User currently offlineMusang From United Kingdom, joined Apr 2001, 864 posts, RR: 7
Reply 18, posted (10 years 5 months 3 weeks 3 days 7 hours ago) and read 6272 times:

Kalakaua - if you can produce a photo of a C-5 showing dihedral/cathedral at any stage of the operation, I'd be very interested!

Thanks - Musang.


User currently offlineFredT From United Kingdom, joined Feb 2002, 2185 posts, RR: 26
Reply 19, posted (10 years 5 months 3 weeks 3 days 6 hours ago) and read 6251 times:

My bad in part, cathedral appears to be an older word for anhedral. I'll doublecheck once I have my aviation dictionaries with me. Never bring your private library to work as you might just need it for important things.  Big grin

However, I would advise using anhedral if you want to be understood. Despite a few years in aviation, I have only heard cathedrals mentioned in religious context until now...

Cheers,
Fred



I thought I was doing good trying to avoid those airport hotels... and look at me now.
User currently offlineKalakaua From United States of America, joined Jan 2004, 1516 posts, RR: 5
Reply 20, posted (10 years 5 months 3 weeks 3 days 4 hours ago) and read 6225 times:

Anhedral can be called also "Cat-hedral." Not cath-edral. My professor was an old man, who preferred the old ways. Sorry for the confusion.

I'll just stick to DI-hedral and AN-heral.

[Edited 2004-03-09 21:52:48]


Gravity explains the motions of the planets, but it cannot explain who set the planets in motion.
User currently offlineKalakaua From United States of America, joined Jan 2004, 1516 posts, RR: 5
Reply 21, posted (10 years 5 months 3 weeks 3 days 4 hours ago) and read 6213 times:

Here's the best photo I could find with the C-5 having dihedral wings in flight.

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Click here for bigger photo!

Photo © Gerhard Plomitzer




Gravity explains the motions of the planets, but it cannot explain who set the planets in motion.
User currently offlineFredT From United Kingdom, joined Feb 2002, 2185 posts, RR: 26
Reply 22, posted (10 years 5 months 3 weeks 3 days 3 hours ago) and read 6185 times:

Kalakaua,
you might want to take a closer look at the perspective in that photo. E g, the angle between the wing and an imaginary line between two of the left and right main gear tires. Still anhedral.

BTW, if someone doesn't call me on writing stability when I meant instability above, I'll get worried about the state of this forum! Big grin

Cheers,
Fred

[Edited 2004-03-09 22:51:59]


I thought I was doing good trying to avoid those airport hotels... and look at me now.
User currently offlineN243NW From United States of America, joined Jul 2003, 1630 posts, RR: 20
Reply 23, posted (10 years 5 months 3 weeks 3 days 3 hours ago) and read 6176 times:

I've heard the wingspan of the B744 grows with a full fuel load due to the droop of the wings and angle of the winglets. Anyone know if this is true?


Yes, it is. When the 744's wing is full of fuel, the outer portions bend down and the winglets are angled further outward, increasing the wing span by 19 inches (48 centimeters).
-N243NW Big grin



B-52s don't take off. They scare the ground away.
User currently offlineKalakaua From United States of America, joined Jan 2004, 1516 posts, RR: 5
Reply 24, posted (10 years 5 months 3 weeks 3 days 1 hour ago) and read 6139 times:

FredT, but, as you see, the wing bent upwards...


Gravity explains the motions of the planets, but it cannot explain who set the planets in motion.
25 Beefmoney : Kalakaua; If you took that C-5 in the photo and looked at it straight on from the front, you would see that the wings are still angled downwards, and
26 Post contains images Kalakaua : Argh. I'll ask my professor, "Old Man" Tracy Doryland. He is a retired Navy pilot, and he himself says the wings are dihedral in flight.
27 Post contains images AJ : If it's not dihedral at liftoff, it isn't going to happen later!
28 Kalakaua : I'll just shut-up. My battle is lost. I won't bother. "The anhedral is required to keep the aircraft from becoming too stable! Large transports have b
29 Liamksa : The C5 has anhedral to counter the lateral stability inherent in high wing designs. Fred, this sentence is fine isn't it? Same reason as for the 146 -
30 QantasA332 : "The C5 has anhedral to counter the lateral stability inherent in high wing designs"...Fred, this sentence is fine isn't it? Yes, it most certainly is
31 MITaero : Is the C-5 wing swept much? Sweep increases effective dihedral, so I'm just curious.
32 QantasA332 : Is the C-5 wing swept much? Sweep increases effective dihedral, so I'm just curious. Yes, the C5's wing has relatively high amount of speep, which, as
33 Post contains links and images Manzoori : Another shot of the C-5 in flight showing Anhedral View Large View MediumPhoto © Art Brett - AirTeamImages Cheers! Rez
34 Post contains images FredT : Liamksa, d'oh! I'll just shut up now and refrain from posting until the course I am taking is over and I have had a week of sleep. Cheers, Fred
35 Lehpron : "Nothing to worry about. Wings are made to flex. If they didn't, they'd snap all the time" That assumes the force would be great enough to kill the wi
36 Starlionblue : Probably... A wing cannot be built strong enough not to flex without an unacceptable (and unnecessary) increase in weight.
37 SlamClick : MrBA You wrote: I've read before that when the B747 wings are fully fueled up it's not advisable to open the over-wing door. For you might not be able
38 AJ : Click, it is true. It has happened more than once on our 747-400s. One experience I saw first hand required defuelling of the outer tanks in order to
39 Air2gxs : SlamClick, I assure that it is true. When I worked for PanAm there were several warnings about opening R3/L3 while fueled for flight. The door opens f
40 Klaus : Sounds logical... even the wing box would flex a little under the changed load, and as long as the upper fuselage is directly mounted to the wing box
41 Galaxy5 : The C-5 with its wing span of 222 feet, is a high mounted, high lift wing, anhedral by design with a 25 degree swept wing. The wing does flex inflight
42 Mr.BA : Thanks Slamclick... good post on how the weight is distributed! Thanks! Mr.BA
43 Post contains images MD-90 : Probably... A wing cannot be built strong enough not to flex without an unacceptable (and unnecessary) increase in weight. True for large transports,
44 Post contains images Starlionblue : So they do bend, even if only a little
45 Mrwayne : slamclick you are wrong MRBA you are wright, The door open over wing would bend the air frame due to the weight of the fuel on board. well done you ha
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