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A380 Wing Flex Compared To The 787  
User currently offlineA380900 From France, joined Dec 2003, 1116 posts, RR: 1
Posted (4 years 8 months 2 days 10 hours ago) and read 21700 times:

I just flew on the A380 on Friday for the first time. I was surprised by the stability of the wing. There was very little flex. Especially compared to the 787. It is surprising because of the unprecedented wingspan of the A380. I understand the 787 is a new technology but why is it that the A380 has so little flex? Is the A380 overbuilt". It does not move at all. Any thoughts? Anybody agrees that the A380 does not seem to be "living" like other planes?

20 replies: All unread, jump to last
 
User currently offlineJBirdAV8r From United States of America, joined Jun 2001, 4491 posts, RR: 21
Reply 1, posted (4 years 8 months 2 days 10 hours ago) and read 21660 times:



Quoting A380900 (Thread starter):
I just flew on the A380 on Friday for the first time. I was surprised by the stability of the wing. There was very little flex. Especially compared to the 787. It is surprising because of the unprecedented wingspan of the A380. I understand the 787 is a new technology but why is it that the A380 has so little flex? Is the A380 overbuilt". It does not move at all. Any thoughts? Anybody agrees that the A380 does not seem to be "living" like other planes?

It has to do with different design requirements more than anything. The A380 wing has to support a massive amount of weight pretty far out on the span for the outboard engines, so naturally, bending moments are going to be a little different. I don't know if I'd say "overbuilt"....rather "differently built."

From an engineering standpoint, I'd say the A380 definitely "lives"--with everything going on system-wise in that airplane, it's impressive!



I got my head checked--by a jumbo jet
User currently offlineBaroque From Australia, joined Apr 2006, 15380 posts, RR: 59
Reply 2, posted (4 years 8 months 2 days 10 hours ago) and read 21415 times:



Quoting A380900 (Thread starter):
I just flew on the A380 on Friday for the first time. I was surprised by the stability of the wing.

Where were you observing it from? The part of the wing with the steep dihedral does not appear to flex much. Were you able to see tip movement?


User currently offlineAA737-823 From United States of America, joined Mar 2000, 5844 posts, RR: 11
Reply 3, posted (4 years 8 months 2 days 9 hours ago) and read 21405 times:



Quoting A380900 (Thread starter):
Is the A380 overbuilt".

Considering the A380 wing snapped broken BEFORE THE LEGAL LIMIT was reached during testing, I'd hardly call the wing overbuilt. Fortunately, they've corrected it.

Quoting A380900 (Thread starter):
It does not move at all.

That's quite incorrect. The A380 exhibits large amounts of wingflex. It may not be visible from the cabin window, but look through some photos in the database. Most notable is the tremendous droop while the aircraft is fully laden with fuel, yet waiting on a taxiway.



Comparing the A380 wing with the 787 wing isn't really a reasonable comparison. The 787 wing is actually carbon-fibre composite (along with other composites), and exhibits many different behavior characteristics from the more commonplace aluminum A380 wing.


User currently offlineTdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 4, posted (4 years 8 months 2 days 8 hours ago) and read 21114 times:



Quoting A380900 (Thread starter):
I understand the 787 is a new technology but why is it that the A380 has so little flex?

As mentioned in other posts, the design drivers are somewhat different. However, the single biggest factor is that the A380 has a very deep wing. Bending stiffness scales with height cubed; being something like 2-3 times as thick as the 787 wing, all other things being equal, would make the A380 wing 8-27 times stiffer. Now, obviously, all other things aren't equal in this case, but you get the idea.

Quoting A380900 (Thread starter):
Is the A380 overbuilt".

Not any more than any other airliner of similar pedigree (i.e. it's packing some extra build to support the presumed A380-900 stretch, just like the 787-8 is for the -9 stretch).

Quoting A380900 (Thread starter):
It does not move at all. Any thoughts?

It's moving some; however, it's so large that movement is more difficult to detect (same reason that large planes look like they're going slower). Also, the A380 has active load alleviation, so the flight controls are countering turbulence that would otherwise result in larger wing flex.

Tom.


User currently offlineAstuteman From United Kingdom, joined Jan 2005, 10070 posts, RR: 97
Reply 5, posted (4 years 8 months 2 days 5 hours ago) and read 20823 times:
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Quoting A380900 (Thread starter):
There was very little flex.

The A380 wing flexes a HUGE amount during the transition from stationary, gravity driven loads, to flying, lift driven loads - a huge amount.

Quoting AA737-823 (Reply 3):
Comparing the A380 wing with the 787 wing isn't really a reasonable comparison. The 787 wing is actually carbon-fibre composite (along with other composites), and exhibits many different behavior characteristics from the more commonplace aluminum A380 wing.

???
There's nothing whatsoever commonplace about the A380's (mostly) aluminium wing. The construction is far from "conventional". ...

Quoting Tdscanuck (Reply 4):
Also, the A380 has active load alleviation, so the flight controls are countering turbulence that would otherwise result in larger wing flex.

  

And the load-alleviation surfaces dance quite spectacularly on occasion..  

Rgds

[Edited 2010-01-31 23:12:51]

User currently offlineSwallow From Uganda, joined Jul 2007, 555 posts, RR: 0
Reply 6, posted (4 years 8 months 2 days 5 hours ago) and read 20819 times:

If you watch a YouTube video of an A380 landing, you will appreciate how the wing tips droop as lift is lost.

If I am not mistaken, this is clearly shown on the EK 380 first landing at JFK



The grass is greener where you water it
User currently offlineFaro From Egypt, joined Aug 2007, 1551 posts, RR: 0
Reply 7, posted (4 years 8 months 2 days ago) and read 19109 times:



Quoting Tdscanuck (Reply 4):
Quoting A380900 (Thread starter):
I understand the 787 is a new technology but why is it that the A380 has so little flex?

As mentioned in other posts, the design drivers are somewhat different. However, the single biggest factor is that the A380 has a very deep wing. Bending stiffness scales with height cubed; being something like 2-3 times as thick as the 787 wing, all other things being equal, would make the A380 wing 8-27 times stiffer. Now, obviously, all other things aren't equal in this case, but you get the idea.

The A380 is also vastly over-winged given that the same wing planform is due to be used on the -900 version of the same. The wing is therefore extremely heavy and exhibits marked droop on the ground which disappears once airborne. This is also wing flex but of a less spectacular variety than on the 787.

Faro



The chalice not my son
User currently offlineTdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 8, posted (4 years 8 months 1 day 23 hours ago) and read 18606 times:



Quoting Faro (Reply 7):
The A380 is also vastly over-winged given that the same wing planform is due to be used on the -900 version of the same. The wing is therefore extremely heavy and exhibits marked droop on the ground which disappears once airborne.

I don't think the droop you see on the ground is because it's massively over-winged...the ground droop has everything to do with the wing weight, not the aircraft weight. So the droop wouldn't change between the -800 and the -900 unless they re-gauged the wing, but if they did that it would suggest that the -800 wing isn't overbuilt (just over-area), therefore not so "massively heavy".

Tom.


User currently offlineAstuteman From United Kingdom, joined Jan 2005, 10070 posts, RR: 97
Reply 9, posted (4 years 8 months 1 day 23 hours ago) and read 18552 times:
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Quoting Tdscanuck (Reply 8):
the ground droop has everything to do with the wing weight

And its contents.....

Rgds


User currently offlineHeavierthanair From Switzerland, joined Oct 2000, 797 posts, RR: 0
Reply 10, posted (4 years 8 months 1 day 22 hours ago) and read 17976 times:

G'day

The single biggest item leading to less "flapping" of the A380 wing in comparison to the B787 wing is the fact the A380 has four engines. The outboard engines provide wing bending relieve thus the outboard section of the wing will flex less due to the weight of the engines.

For this very reason the A330 wing needed reenforcement in comparison to the otherwise identical A340 wing, to compensate for having no wing bending relieve on the 2 engined aircraft.

Presumably the wing flex on the A330 is similar to the B787.  


Cheers

Peter



"Two things are infinite: the universe and human stupidity; and I'm not sure about the universe." (Albert Einstein, 1879
User currently offlineA380900 From France, joined Dec 2003, 1116 posts, RR: 1
Reply 11, posted (4 years 8 months 1 day 22 hours ago) and read 17700 times:



Quoting Baroque (Reply 2):
Where were you observing it from? The part of the wing with the steep dihedral does not appear to flex much.

40L. Maybe 10 rows or so behind the wing. I could see the wing tip.

Quoting Astuteman (Reply 5):
And the load-alleviation surfaces dance quite spectacularly on occasion..

True. I think there were very little turbulence on my flight. Maybe it's gonna be more eventful on the way back.

The overall impression is of a very rigid plane. Even on the ground. It does not seem like the plane is very flexible. Maybe is it because the airframe is brand new? Maybe things get a little "looser" with time?

I remember taxiing with other planes where every bump on a taxiway would make the wing vibrate big time.


User currently offlineEA772LR From United States of America, joined Mar 2007, 2836 posts, RR: 10
Reply 12, posted (4 years 8 months 1 day 21 hours ago) and read 16928 times:

It's hard to elaborate further than what has been stated above so I'll just say that although the A380 doesn't have the dihedral bend in the wings that the 787 has, outside of the 787, the A380 wing is the most beautiful and impressive (from an engineering standpoint alone) I've ever seen.


We often judge others by their actions, but ourselves by our intentions.
User currently offlineMD80fanatic From United States of America, joined Apr 2004, 2660 posts, RR: 9
Reply 13, posted (4 years 8 months 1 day 21 hours ago) and read 16665 times:

There is tremendous flex on the 380, just not what you expect. A straight looking wing (in flight) is flexed greatly from it's droopy look while on the ground as it strains to hold up the outboard engines.

User currently offlineSEPilot From United States of America, joined Dec 2006, 6924 posts, RR: 46
Reply 14, posted (4 years 8 months 1 day 20 hours ago) and read 16099 times:

Actually, the difference is primarily the difference in fatigue and stiffness characteristics between Al and CFRP. CFRP has much better fatigue resistance, and that also means that its ratio of stiffness to ultimate strength is actually lower. So CFRP will flex a lot more with the same ultimate strength; and that flexing will not lead to fatigue, as the CFRP does not fatigue as Al does. The wing flex is a mixed blessing; it does help smooth the flight in turbulence, but it also means slightly less efficiency due to enhanced dihedral effect. It is not really a lot to do with the design of the wings; a wing made of CFRP with the wing span and the ultimate strength of the 787 wing will flex pretty much as much as the 787 does; likewise the A380 wing will flex pretty much the same as any Al wing with the same span and strength, although design can change the deflection in both cases within limits. The CFRP center wing box on the A380 probably means that it does flex more than, say a 747, as the wing box will flex a bit more than it would if it were Al.


The problem with making things foolproof is that fools are so doggone ingenious...Dan Keebler
User currently offlineKonstantinkoll From Germany, joined Aug 2006, 99 posts, RR: 2
Reply 15, posted (4 years 8 months 1 day 19 hours ago) and read 15310 times:



Quoting Heavierthanair (Reply 10):
For this very reason the A330 wing needed reenforcement in comparison to the otherwise identical A340 wing, to compensate for having no wing bending relieve on the 2 engined aircraft.

To illustrate this point:

Big version: Width: 240 Height: 180 File size: 8kb

A330

Big version: Width: 240 Height: 180 File size: 8kb

A340


User currently offlineJSquared From United States of America, joined Sep 2006, 149 posts, RR: 0
Reply 16, posted (4 years 8 months 1 day 18 hours ago) and read 14285 times:

The 747-8 has two engines on each wing and appears to flex quite a bit.
http://blog.flightstory.net/wp-content/uploads/747-8i-ext.jpg


User currently offlineMSNYX From United States of America, joined Dec 2006, 130 posts, RR: 0
Reply 17, posted (4 years 8 months 1 day 14 hours ago) and read 12077 times:



Quoting A380900 (Thread starter):
It is surprising because of the unprecedented wingspan of the A380.

Not quite unprecedented...

http://www.aerospaceweb.org/question/design/size/size-comparison.jpg



If I rise on the wings of the dawn, if I settle on the far side of the sea, even there Your hand will guide me
User currently offlineFlyBoy747 From United States of America, joined Sep 2009, 6 posts, RR: 0
Reply 18, posted (4 years 8 months 1 day 14 hours ago) and read 11777 times:
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Here is a video of the A380 landing in JFK. You can see the difference from right before touchdown to where just after touchdown and the wing is not producing anymore lift. It is far from the 787 in wing flex; however, it does show that the massive wing does flex. Comparing the 787 and A380 is like comparing Apples to Oranges. They are both amazing works of engineering but each is made from completely different materials. Comparing the 787 and A350 or the 747 and the A380 would be better comparisons.

http://www.youtube.com/watch?v=1G5bTRnmLHU

Also here is one of the A380 landing in Oshkosh, WI for the EAA airshow. Hard landing but you can see the wing flex due said landing. Quite the bounce in her step I might add.  bouncy 

http://www.youtube.com/watch?v=-yi9C8NE3Ek



MSP is my home...no matter where I fly!
User currently offlineBluemoonUK From United Kingdom, joined Jul 2000, 105 posts, RR: 0
Reply 19, posted (4 years 8 months 1 day 13 hours ago) and read 11450 times:

I was sat upstairs,on my flight, and saw plenty of wing flex on approach to Changi on a humid spring morning.
Bluemoon


User currently offlineAA737-823 From United States of America, joined Mar 2000, 5844 posts, RR: 11
Reply 20, posted (4 years 8 months 1 day 12 hours ago) and read 10804 times:

I think we have adequately argued that there is, in fact wingflex on this aircraft.
Must we continue to argue the point?

Quoting Astuteman (Reply 5):
There's nothing whatsoever commonplace about the A380's (mostly) aluminium wing.

Insofar as the context under which I wrote, you've made an oxymoronic statement.
See next quote:

Quoting SEPilot (Reply 14):
likewise the A380 wing will flex pretty much the same as any Al wing



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