js
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747-400 Wing Flex

Fri Jun 11, 2004 7:55 am

Using the winglets as a point of reference, these two pictures gives some idea as to how much a 747-400 wing flexes on takeoff! Can anyone estimate the difference in height?

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PhilSquares
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RE: 747-400 Wing Flex

Fri Jun 11, 2004 8:05 am

At MTOW the wing flex is almost 3 meters at the tip as compared to the wing tip position on the ground.
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FL1TPA
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RE: 747-400 Wing Flex

Fri Jun 11, 2004 8:17 am

Looking at the flex from the angle in the photo below is quite amazing! The engineering that goes into these aircrafts is mind-boggling.


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Jetfixer75
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RE: 747-400 Wing Flex

Fri Jun 11, 2004 10:14 am

The 747-400 wing can deflect a total of 29 ft from top to bottom before the spars fail!!! Absolutely amazing. I have the destructive test on video when Boeing does this, sounds like a bomb going off
 
smcmac32msn
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RE: 747-400 Wing Flex

Fri Jun 11, 2004 10:19 am

Jetfixer75 - Is that a personal video, or can you post it for us to see?
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md80fanatic
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RE: 747-400 Wing Flex

Fri Jun 11, 2004 10:25 am

That last pic shows an unusual amount of flex.....due primarily to the fact that the pilot has extended his slats....which creates a very large roiling motion of the air below the wing increasing pressure greatly (extra lift). That has to be the most that wing can flex before a stress fracture appears. That pic's a keeper for sure.
 
LVZXV
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RE: 747-400 Wing Flex

Fri Jun 11, 2004 10:35 am

I remember reading that passengers noted an abnormal amount of wing flex on a BA 741 flying JFK-LHR c.1999. One passenger even described a mild "flapping" notion during the cruise. When the aircraft landed, it was withdrawn from service and immediately inspected. The Jumbo had crossed the North Atlantic with a BROKEN wing spar!!!  Wow! Beat that Airbus!!!  Big thumbs up

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ATA L1011
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RE: 747-400 Wing Flex

Fri Jun 11, 2004 10:45 am

All of the long wing modern widebodies have lots of flex in cruise,takeoff and landing including these;

767
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777
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A330/A340
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I have noticed lots of flex on these models.
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B4REAL
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RE: 747-400 Wing Flex

Fri Jun 11, 2004 12:01 pm

Jetfixer75:

IIRC wasn't 29 feet where the 777's wings fall apart? That video was public on the Discovery channel recently. They re-run the doc on the 777 periodically, also on Discovery Wings.
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airportugal310
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RE: 747-400 Wing Flex

Fri Jun 11, 2004 12:06 pm

Seems to me that the longer the wing, the greater the chance of flexing...rational thinking or just obvious?

I also think that the location of the engine matters, so that may be just coincidence!

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noelg
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RE: 747-400 Wing Flex

Fri Jun 11, 2004 5:00 pm

I flew on a MH 747-400 recently from KUL-LHR and it was amazing to see from behind the wing the difference - before pushback the wings (being full of fuel) were bent down at the end, hardly giving enough room for the fuel truck that was there.

After landing, as we taxied in, we went past a BA A320 and the wingtip was higher than we were in the cabin, higher than the A320 as well!

Quite interesting to see the difference!
 
Rotate
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RE: 747-400 Wing Flex

Fri Jun 11, 2004 6:02 pm

wingflex is definetely higher/greater due on landing, than on takeoff ....


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NBGSkyGod
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RE: 747-400 Wing Flex

Sat Jun 12, 2004 7:30 am

The more weight the plane has the more the wing will flap. The C5's wing flapping is so bad it has a damping system to limit it, if that system fails the plane tends to resemble a large bird flapping through the air, and I would imagine not too much fun for those riding inside.
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whitehatter
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RE: 747-400 Wing Flex

Sat Jun 12, 2004 7:58 am

If the wings DIDN'T flex I'd be worried!  Nuts

Flexing is designed into the wings of large aircraft. If they just sat there rigid, then where would the changes in stress and vibration be going? A fully rigid wing on a 747 would be under all kinds of changing pressures and much more prone to stress fractures.

Think of dropping a plate on the floor. A bendy plastic one just bounces, a ceramic/pottery one shatters. That flex absorbs a lot of punishment and shock!
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aviopic
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RE: 747-400 Wing Flex

Sat Jun 12, 2004 8:21 am

I hardly see any flex in a 743 wing, can someone tell me the difference in flex movement between 744 and 743.
I have read the 744 wing can flex 29ft. but what about a 743 wing ?


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Toni_
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RE: 747-400 Wing Flex

Sat Jun 12, 2004 9:41 am

That's because of the greater wingspan. The 744 has a wingspan of 64 meters, and a 747 classic 59 meters. And also I think the winglets make it a bit easier to detect the wing flex from a distance on a 744. It's the combination of winglets and great wingspan that make the A330 look like a huge albatross stretching its wings while gliding above the ocean.

As for the max a 743 wing can take... I think the first 747 test wing back in 1969 snapped at 10 meters... Still very impressive!
 
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Starlionblue
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RE: 747-400 Wing Flex

Sat Jun 12, 2004 5:08 pm

As for flying with a broken wing spar, the 747 cheats since it has three spars as opposed to the usual two.  Big grin
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LVZXV
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RE: 747-400 Wing Flex

Sun Jun 13, 2004 9:13 am

10 metres = 30 feet

All 747s have the same SPAR, hence they all snap within a foot of each other.

XV

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Jetfixer75
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RE: 747-400 Wing Flex

Sun Jun 13, 2004 3:19 pm

The video I have is from Discovery Wings. It was taken during the destructive testing of the 744. I'll have to look for it and see if I can figure out how to post it on here.
 
squirrel83
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RE: 747-400 Wing Flex

Mon Jun 14, 2004 12:49 am

I love the NW JFK 747-4 Dept picture

As stated ~ WOW

Looking at the flex from the angle in the photo below is quite amazing! The engineering that goes into these aircrafts is mind-boggling.

I love 747-4 they are really quite amazing but Just think if you were to see a smurf in the isle?
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Go3Team
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RE: 747-400 Wing Flex

Mon Jun 14, 2004 1:06 am

"I'll have to look for it and see if I can figure out how to post it on here. "

Try: http://www.movie-host.net They handle uploads up to 35 megabytes. Totally anonymous, and free.
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Starlionblue
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RE: 747-400 Wing Flex

Mon Jun 14, 2004 4:22 am

For the record, 10 metres = 32.8 feet.

Source: www.onlineconversion.com
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