grantcv
Posts: 410
Joined: Tue Apr 26, 2005 1:28 pm

Bending Wings On B787

Tue May 03, 2005 1:48 pm

It seems from Boeing's recent 787 images that the wings will really flex upwards in flight. I have noticed a similar thing when aboard a 772, but this seems more pronounced. Why is this? What aerodynamic benefit is there?
I am assuming this won't be evident when the plane is on the ground much as it isn't with the 777.
 
NAV20
Posts: 8453
Joined: Thu Nov 27, 2003 3:25 pm

RE: Bending Wings On B787

Tue May 03, 2005 2:07 pm

All wings flex under load, Grantcv. They're designed to do so, same as the springs in the chair you're sitting in.

An aeroplane with rigid wings would be like a concrete armchair - and just about as heavy  Smile
"Once you have flown, you will walk the earth with your eyes turned skywards.." - Leonardo da Vinci
 
DfwRevolution
Posts: 8655
Joined: Sat Jan 09, 2010 7:31 pm

RE: Bending Wings On B787

Tue May 03, 2005 2:10 pm

Quoting Grantcv (Thread starter):
Why is this?

Nature of composite wings: much more pronounced flex.

Quoting Grantcv (Thread starter):
What aerodynamic benefit is there?

I'm not an aerodynamics expert, so I'm vulnerable here, but I would suspect there is benefit to be derrived. I'd guess (and that's it: a guess) that some wingtip vorticies would be reduced by such "bending" (dihedral?). The 787 looks remarkeably like a bird in-flight, and winglets work by a simmilar process on a smaller scale

http://www.csinews.net/images_antarctica/bird-flying-small.jpg

http://www.boeing.com/commercial/7e7/k63304-3.html
 
KDTWflyer
Posts: 787
Joined: Tue Jun 29, 2004 12:51 pm

RE: Bending Wings On B787

Tue May 03, 2005 2:17 pm

I wonder if the ease of flex because of the composites will lessen the effects of turbulence on the plane a little.
NW B744 B742 B753 B752 A333 A332 A320 A319 DC10 DC9 ARJ CRJ S340
 
flybyguy
Posts: 1415
Joined: Sun Jun 27, 2004 12:52 pm

RE: Bending Wings On B787

Tue May 03, 2005 2:18 pm

Possibly, Boeing has designed the 787 with thinner wings to optimize high altitude cruise efficiency. Thinner wings have less drag and unfortunately less structural support, therefore more pronounced wing flex.
"Are you a pretender... or a thoroughbred?!" - Professor Matt Miller
 
Ruscoe
Posts: 1587
Joined: Sun Aug 22, 1999 5:41 pm

RE: Bending Wings On B787

Tue May 03, 2005 2:25 pm

When I was at the Australian Airshow at Avalon this year had a chance to talk to one of the Boeing reps. He told me the wings will flex 16 feet (4m) in flight.
Looking at that through the bigger windows might just scare a few inexperienced fliers!

Ruscoe
 
masseybrown
Posts: 4492
Joined: Wed Dec 11, 2002 2:40 pm

RE: Bending Wings On B787

Tue May 03, 2005 2:27 pm

Quoting DfwRevolution (Reply 2):
The 787 looks remarkeably like a bird in-flight,

Nice observation; I thought that, too. The bend of the wingtips looks like the flex in an eagle's feathers in one of the illustrations.
 
grantcv
Posts: 410
Joined: Tue Apr 26, 2005 1:28 pm

RE: Bending Wings On B787

Tue May 03, 2005 2:29 pm

Quoting Grantcv (Thread starter):
All wings flex under load, Grantcv. They're designed to do so, same as the springs in the chair you're sitting in.

An aeroplane with rigid wings would be like a concrete armchair - and just about as heavy

I know that, but the flex is much more pronounced here. Same thing on the 777 - when the plane in in the air, the wings bend up quite a bit. The first time I flew aboard a 777, I was amazed to see how much they were bending up. The latest issue of Aviation Week & Space Technology refers to the dihedral wing noting that they will bend more than any other wing. I am wondering why this is a good thing - there must be an areodynamic benefit to a dihedral wing.
 
Jet-lagged
Posts: 819
Joined: Mon Mar 04, 2002 11:58 pm

RE: Bending Wings On B787

Tue May 03, 2005 3:57 pm

Good question for the Technical Forum.
 
trent900
Posts: 499
Joined: Wed Dec 17, 2003 6:06 am

RE: Bending Wings On B787

Tue May 03, 2005 8:43 pm

Quoting Ruscoe (Reply 5):
Looking at that through the bigger windows might just scare a few inexperienced fliers!

I should think if flying through heavy turbulence there will be a noticable up and down movement at the wing tip. What will nervous passengers think about this? My dad said the 737NG is bad enough, and for shortish wings they flex a lot.

D.
 
Glom
Posts: 2051
Joined: Sat Apr 23, 2005 2:38 am

RE: Bending Wings On B787

Tue May 03, 2005 9:32 pm

Quoting Grantcv (Reply 7):
there must be an areodynamic benefit to a dihedral wing.

It makes the aircraft stable in the role. If the aircraft tries to roll a bit to one side, the dihedral causes to role back the other way creating stable equilibrium. Military fast jets have anhedral, which makes the aircraft unstable in the role. This is because it makes the aircraft very readily maneuverable.

Quoting Ruscoe (Reply 5):
Looking at that through the bigger windows might just scare a few inexperienced fliers!

I was impressed by the wing flex on the 777 last time I flew on one. I find it more comforting to see a flexible wing than a rigid wing that is likely to snap.
 
jetBlue
Posts: 347
Joined: Sun Sep 05, 2004 9:12 am

RE: Bending Wings On B787

Tue May 03, 2005 11:37 pm

Quoting Ruscoe (Reply 5):
Looking at that through the bigger windows might just scare a few inexperienced fliers!

When I was on the MD-11, the wings appeared to shake and bend at the tip a lot more than on the 777. And the 777's wing bends more, as a whole, I would say.

Despite the high wing flex, the 777 appears to stay "in shape" during turbulence a lot more than other planes of similar size.

jetBlue
We know for you it's not just a seat on a flight to a place. It's a seat on a flight to your life.
 
mrocktor
Posts: 1391
Joined: Mon Jan 24, 2005 12:57 am

RE: Bending Wings On B787

Wed May 04, 2005 12:34 am

The wing flexes because it is less rigid then typical airliner wings. It is less rigid because it was designed to be less rigid. It was designed to be less rigid because that way it is lighter.

You can design a rigid composite wing, you can design a flexible metal wing and you sure as hell can design a rigid wing with as much dihedral as you like.

The 787 wing flex is the result of reducing weight on the wing structure. It is only practical with advanced structural analysys, computational fluid dynamics and flight control system capabilities.

If a rigid wing could be made as light as a flexible one, all wings would be rigid. Much less trouble that way...

mrocktor
 
Glom
Posts: 2051
Joined: Sat Apr 23, 2005 2:38 am

RE: Bending Wings On B787

Wed May 04, 2005 12:57 am

Would a high degree of wing flex have an adverse effect on lift?
 
gigneil
Posts: 14133
Joined: Fri Nov 08, 2002 10:25 am

RE: Bending Wings On B787

Wed May 04, 2005 12:59 am

Quoting KDTWFlyer (Reply 3):
I wonder if the ease of flex because of the composites will lessen the effects of turbulence on the plane a little.

This is supposed to be a major benefit of the 787.

N
 
Areopagus
Posts: 1327
Joined: Thu Sep 20, 2001 12:31 pm

RE: Bending Wings On B787

Wed May 04, 2005 6:49 am

from the Seattle Post-Intelligencer:

The 787's wings will also be composite. Passengers seated next to the large windows on the 787 will notice those wings bent upward in flight more than they would be on the 777, Gillette said.

The 777 is a much larger plane. But because composites are stronger than aluminum, Boeing is giving the 787 the same wingspan as that of the 777-200, but with about 20 percent less surface area. As a result, the wing will flex more during flight.

Boeing hopes to have a large model of the 787 with its wings bent upward for display at the Paris Air Show in June.
 
Ken777
Posts: 9103
Joined: Thu Mar 11, 2004 5:39 am

RE: Bending Wings On B787

Wed May 04, 2005 7:07 am

I think that the head on illustration of the 787 was given a lot of wing flex to make it more dramatic - the other illustrations didn't show that much flex.

I'm always amazed at the flex in the wings of a 744 - watch them change on both take offs and landings. I think the 380's will be rather impressive also when it's fully loaded.
 
squirrel83
Posts: 1219
Joined: Mon May 24, 2004 12:28 pm

RE: Bending Wings On B787

Wed May 04, 2005 7:10 am

With a more flexible wing wouldn't that create more turbulence?
A346, 7E7, 747, 777, Sonic Cruiser
 
mrcomet
Posts: 575
Joined: Mon Mar 28, 2005 5:53 am

RE: Bending Wings On B787

Wed May 04, 2005 7:21 am

I am not sure about the aerodynamics either but I imagine that some bending would give a similar advantage as wing tips ....i.e. it is harder for the high pressure air below the wing to bleed into the low pressure area. Please correct me if I am mistaken.
The dude abides
 
gaut
Posts: 436
Joined: Sat Dec 15, 2001 10:57 am

RE: Bending Wings On B787

Wed May 04, 2005 7:27 am

Quoting Ken777 (Reply 16):
I'm always amazed at the flex in the wings of a 744 - watch them change on both take offs and landings. I think the 380's will be rather impressive also when it's fully loaded.

According to Airbus.com: "During take-off, the wing will flex upwards by over 4 meters"
«Horum omnium fortissimi sunt Belgae.»
 
DfwRevolution
Posts: 8655
Joined: Sat Jan 09, 2010 7:31 pm

RE: Bending Wings On B787

Wed May 04, 2005 7:29 am

Quoting Squirrel83 (Reply 17):
With a more flexible wing wouldn't that create more turbulence?

No, think about it as the shock-absorbers on your car. The ability for your shocks to stretch up and down dapens the bumps in the road. Likewise, a non-rigid wing transfers the energy absorbed from hitting up/downdrafts into wing flex.... rather than transfering that energy to your seat.
 
trent900
Posts: 499
Joined: Wed Dec 17, 2003 6:06 am

RE: Bending Wings On B787

Wed May 04, 2005 6:37 pm

Quoting Ken777 (Reply 16):
I think the 380's will be rather impressive also when it's fully loaded.

The 380's wings did flex upwards by about 4 meters during the take-off. This is noticable if you look closely at film footage during its take-off run, the wings seem to straiten out.

D.

Popular Searches On Airliners.net

Top Photos of Last:   24 Hours  •  48 Hours  •  7 Days  •  30 Days  •  180 Days  •  365 Days  •  All Time

Military Aircraft Every type from fighters to helicopters from air forces around the globe

Classic Airliners Props and jets from the good old days

Flight Decks Views from inside the cockpit

Aircraft Cabins Passenger cabin shots showing seat arrangements as well as cargo aircraft interior

Cargo Aircraft Pictures of great freighter aircraft

Government Aircraft Aircraft flying government officials

Helicopters Our large helicopter section. Both military and civil versions

Blimps / Airships Everything from the Goodyear blimp to the Zeppelin

Night Photos Beautiful shots taken while the sun is below the horizon

Accidents Accident, incident and crash related photos

Air to Air Photos taken by airborne photographers of airborne aircraft

Special Paint Schemes Aircraft painted in beautiful and original liveries

Airport Overviews Airport overviews from the air or ground

Tails and Winglets Tail and Winglet closeups with beautiful airline logos