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ACATROYAL
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Winglets On a A380

Tue Sep 06, 2016 10:10 am

Just curious if there is a possibility of Winglets, Sharklets, type additions being added to the A380. I keep reading about the A380 needing to be more efficient in order to be more appealing to potential customers. I personally think they would look great with them added on.
 
AustrianZRH
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Re: Winglets On a A380

Tue Sep 06, 2016 10:14 am

IIRC, the problem with winglets was that the wingspan wouldn't fit into the 80-m-box any more, giving even more problems with airport compatibility. However, I do NOT keep reading that the A380 is too inefficient - rather that it's efficiency is remarkable, as long as it is not flying around half empty. And filling it seems to be the problem - which is a shame as I am a 380 fan :).
 
ACATROYAL
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Re: Winglets On a A380

Tue Sep 06, 2016 10:34 am

Thanks for the answer
 
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BoeingVista
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Re: Winglets On a A380

Tue Sep 06, 2016 10:42 am

AustrianZRH wrote:
IIRC, the problem with winglets was that the wingspan wouldn't fit into the 80-m-box any more, giving even more problems with airport compatibility. However, I do NOT keep reading that the A380 is too inefficient - rather that it's efficiency is remarkable, as long as it is not flying around half empty. And filling it seems to be the problem - which is a shame as I am a 380 fan :).


You are forgetting that the wing fence assembly takes up the last 3-4 meters or so of wingtip, there is nothing stopping Airbus redesigning the assembly to make it into a sharklette and remain within the 80m box.
 
AustrianZRH
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Re: Winglets On a A380

Tue Sep 06, 2016 11:12 am

BoeingVista wrote:
You are forgetting that the wing fence assembly takes up the last 3-4 meters or so of wingtip, there is nothing stopping Airbus redesigning the assembly to make it into a sharklette and remain within the 80m box.

I didn't think the wingtip assembly uses that much lenght, wow! Thanks for the input.
 
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Polot
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Re: Winglets On a A380

Tue Sep 06, 2016 11:23 am

BoeingVista wrote:
AustrianZRH wrote:
IIRC, the problem with winglets was that the wingspan wouldn't fit into the 80-m-box any more, giving even more problems with airport compatibility. However, I do NOT keep reading that the A380 is too inefficient - rather that it's efficiency is remarkable, as long as it is not flying around half empty. And filling it seems to be the problem - which is a shame as I am a 380 fan :).


You are forgetting that the wing fence assembly takes up the last 3-4 meters or so of wingtip, there is nothing stopping Airbus redesigning the assembly to make it into a sharklette and remain within the 80m box.

I don't think the wing fence assembly is taking up anywhere close to that much space in the wingspan... (I assume you mean 3-4 m across both wings, because 3-4 m per a wing for wingtip fences is absurd).
 
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BoeingVista
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Re: Winglets On a A380

Tue Sep 06, 2016 1:31 pm

Polot wrote:
BoeingVista wrote:
AustrianZRH wrote:
IIRC, the problem with winglets was that the wingspan wouldn't fit into the 80-m-box any more, giving even more problems with airport compatibility. However, I do NOT keep reading that the A380 is too inefficient - rather that it's efficiency is remarkable, as long as it is not flying around half empty. And filling it seems to be the problem - which is a shame as I am a 380 fan :).


You are forgetting that the wing fence assembly takes up the last 3-4 meters or so of wingtip, there is nothing stopping Airbus redesigning the assembly to make it into a sharklette and remain within the 80m box.

I don't think the wing fence assembly is taking up anywhere close to that much space in the wingspan... (I assume you mean 3-4 m across both wings, because 3-4 m per a wing for wingtip fences is absurd).


Well its an absurdly large aircraft..

Image

Assuming an average man of roughly 1.75m for scale the wing fence is easily a meter taller than him, and you can see that the tip that is attached to the fence is substantial. I stand by 3-4 m per wing as a removable structure that could be reworked into a sharklet.
 
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thefactorypilot
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Re: Winglets On a A380

Wed Sep 07, 2016 1:09 am

BoeingVista wrote:
Polot wrote:
BoeingVista wrote:

You are forgetting that the wing fence assembly takes up the last 3-4 meters or so of wingtip, there is nothing stopping Airbus redesigning the assembly to make it into a sharklette and remain within the 80m box.

I don't think the wing fence assembly is taking up anywhere close to that much space in the wingspan... (I assume you mean 3-4 m across both wings, because 3-4 m per a wing for wingtip fences is absurd).


Well its an absurdly large aircraft..

Image

Assuming an average man of roughly 1.75m for scale the wing fence is easily a meter taller than him, and you can see that the tip that is attached to the fence is substantial. I stand by 3-4 m per wing as a removable structure that could be reworked into a sharklet.

That structure you are seeing inboard of the fence is still part of the airfoit... its just where airbus chose to begin the winglet piece. beginning a winglet back there wouldn't have much benefit over what they have now... a piece of span followed by a fence. I'm quite sure that the aero engineers at Airbus know a bit about what they are doing.
 
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BoeingVista
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Re: Winglets On a A380

Wed Sep 07, 2016 2:15 am

thefactorypilot wrote:
BoeingVista wrote:
Polot wrote:
I don't think the wing fence assembly is taking up anywhere close to that much space in the wingspan... (I assume you mean 3-4 m across both wings, because 3-4 m per a wing for wingtip fences is absurd).


Well its an absurdly large aircraft..

Image

Assuming an average man of roughly 1.75m for scale the wing fence is easily a meter taller than him, and you can see that the tip that is attached to the fence is substantial. I stand by 3-4 m per wing as a removable structure that could be reworked into a sharklet.

That structure you are seeing inboard of the fence is still part of the airfoit... its just where airbus chose to begin the winglet piece. beginning a winglet back there wouldn't have much benefit over what they have now... a piece of span followed by a fence. I'm quite sure that the aero engineers at Airbus know a bit about what they are doing.


Yes, it is part of the airfoil and hence span already, but the debate was about whether you could fit a winglet and remain within the 80m box; clearly looking at the extent of the winglet piece the answer to that is yes.

I would also argue that as an upward curve would increase efective span and a more advanced tip treatment could reduce drag you could make a performance difference to the aircraft.
 
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DocLightning
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Re: Winglets On a A380

Wed Sep 07, 2016 4:38 am

BoeingVista wrote:
thefactorypilot wrote:
BoeingVista wrote:

Well its an absurdly large aircraft..

Image

Assuming an average man of roughly 1.75m for scale the wing fence is easily a meter taller than him, and you can see that the tip that is attached to the fence is substantial. I stand by 3-4 m per wing as a removable structure that could be reworked into a sharklet.

That structure you are seeing inboard of the fence is still part of the airfoit... its just where airbus chose to begin the winglet piece. beginning a winglet back there wouldn't have much benefit over what they have now... a piece of span followed by a fence. I'm quite sure that the aero engineers at Airbus know a bit about what they are doing.


Yes, it is part of the airfoil and hence span already, but the debate was about whether you could fit a winglet and remain within the 80m box; clearly looking at the extent of the winglet piece the answer to that is yes.

I would also argue that as an upward curve would increase efective span and a more advanced tip treatment could reduce drag you could make a performance difference to the aircraft.


The section outboard of the last slat/aileron is about 2m until the wingtip. You'd have to blend the wingtip and cant it outboard enough that wing flex at rotation wouldn't tilt the whole surface inward (which would reduce efficiency to the point of not being worth it). Is it doable? Not sure. Will it be done, given that there haven't been any new A380 orders in a long time? Unlikely.
 
WIederling
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Re: Winglets On a A380

Wed Sep 07, 2016 8:36 am

documents quite well what is wingtip and what is core wing:
http://www.airlinereporter.com/2011/06/ ... s-airshow/
I don't think that the wing fence goes much more than 1m inboard. IMHO probably less.
 
Fabo
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Re: Winglets On a A380

Wed Sep 07, 2016 10:26 am

I'm quite sure Airbus engineers considered options of shorter wing with winglet or raked wingtip... The technology was well known by the time the wing was designed.

They would have decided, that a bit more length in the airfoil was worth the disadvantage of not having a different wingtip device.
 
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AA777223
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Re: Winglets On a A380

Wed Sep 07, 2016 4:53 pm

Why is airbus so big on the fences? We saw them on the later A300/10s, A32X and A380. Boeing seems to really like the blended and raked winglets, which I was under the impression were a decent bit more efficient. Any info is appreciated.
 
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Polot
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Re: Winglets On a A380

Wed Sep 07, 2016 5:38 pm

AA777223 wrote:
Why is airbus so big on the fences? We saw them on the later A300/10s, A32X and A380. Boeing seems to really like the blended and raked winglets, which I was under the impression were a decent bit more efficient. Any info is appreciated.


Because for the A300/A310 that is where the commercial technology/know how was at at the moment (although obviously there was extensive studying on winglets at the time, especially by NASA). With the A320 they stuck with what they knew to quickly/cheaply improve the plane (remember the A320-100 lacked the fences).

For the A380 is was all about size constraints- they needed to stay within the 80m box and apparently having a larger wing + fences was preferred over a smaller wing + winglets.
 
VSMUT
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Re: Winglets On a A380

Wed Sep 07, 2016 5:39 pm

AA777223 wrote:
Why is airbus so big on the fences? We saw them on the later A300/10s, A32X and A380. Boeing seems to really like the blended and raked winglets, which I was under the impression were a decent bit more efficient. Any info is appreciated.


First of all, you need to look at the timeline for when they were implemented. The Airbus fences were designed and introduced in the 1980s, and were among the first winglets installed on production airliners. Airbus actually moved away from the wing fence with the A330 and A340, and that was in 1988. The A380 differed because the wingspan would have been too big with A330/A340 style winglets.
The blended and raked winglets found on Boeing weren't introduced until 2002 and 2000 respectively.
 
WIederling
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Re: Winglets On a A380

Wed Sep 07, 2016 5:48 pm

1: wingtip device gains depend on the wing layout you want to add them to.
( lift distribution influences the tip vortex, the expensive large and complex winglets work better on a stronger vortex.
guess: going by the rework needed to fit sharklets the A320 wing already has less lift on the outer ends than a 737 )

2. the fences have a different gains profile.

Alltogether there is more PR "what Boeing uses is invariably better" involved than actual hands down advantages.
IMU Airbus now seems to have managed a design that produces a gains step from wingfence to sharklet that compares well to the no winglets to winglet gains on 737.
 
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Balerit
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Re: Winglets On a A380

Wed Sep 07, 2016 5:53 pm

Also remember that Airbus was embroiled in the controversy over the patent of winglets and thus could not install them until they came up with the sharklet idea.
 
WIederling
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Re: Winglets On a A380

Wed Sep 07, 2016 6:45 pm

Balerit wrote:
Also remember that Airbus was embroiled in the controversy over the patent of winglets and thus could not install them until they came up with the sharklet idea.


The APB patent has long been voided. ( following an Airbus call to investigate. It did nothing more than describe a a generic optimisation process while the basic concept of winglets had an overflow of prior art.)
 
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Matt6461
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Re: Winglets On a A380

Wed Sep 07, 2016 10:53 pm

WIederling wrote:
1: wingtip device gains depend on the wing layout you want to add them to.
( lift distribution influences the tip vortex, the expensive large and complex winglets work better on a stronger vortex.
guess: going by the rework needed to fit sharklets the A320 wing already has less lift on the outer ends than a 737 )


I think this is backwards: the A320 probably already had more lift on the outboard sections than the 737. The function of a winglet is basically to move lift outboard.
Therefore, a wing that sees less winglet benefit probably had more outboard lift to begin with.
Induced drag isn't solely a phenomenon of tip vortices, it creates vorticity across a much larger field determined by span and lift.
For a given span and lift, drag is minimized by an elliptical lift distribution. Fuselage interference makes an elliptical distribution practically impossible, of course...

The A380 actually has an inboard-loaded wing (Airbus changed the lift distribution during detailed design to shed weight. This may have been a choice to meet contractual OEW guarantees at the expense of fuel efficiency, IDK. Fuel was cheaper back then...).
The wing-twist revision from a few years ago probably reversed this change somewhat by increasing the Cl of the outboard portions relative to the inboard portions of the wing.
But it's probably still more inboard-loaded than usual, so an advanced winglet could theoretically benefit the A380 more than usual.
Folks here have pointed to good reasons, however, why there may not be room for a blended winglet outboard of the aileron and inboard of 80 meters. Winglets have to curved roughly parabolically to have decent impact, which would require several meters of span. The 744 winglet, for example, has little marginal effect because it isn't optimally curved.

In any event, it's unlikely we'll see significant investment in a winglet, given the A380's lack of sales. It's pretty much a zombie program now. No point tinkering with a massively sub-optimal plane.
 
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Balerit
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Re: Winglets On a A380

Thu Sep 08, 2016 3:38 am

WIederling wrote:
Balerit wrote:
Also remember that Airbus was embroiled in the controversy over the patent of winglets and thus could not install them until they came up with the sharklet idea.


The APB patent has long been voided. ( following an Airbus call to investigate. It did nothing more than describe a a generic optimisation process while the basic concept of winglets had an overflow of prior art.)


Air War: 'Winglet' Versus 'Sharklet'

Hoping to avoid paying royalties to Aviation Partners, Airbus filed a federal lawsuit against the smaller Seattle-based company in December, asking a judge to rule its winglets patent invalid. In January, it also persuaded the U.S. Patent and Trademark Office to re-examine the company's 18-year-old patent on the winglets, which bend skyward from a plane's wingtips like the ends of a handlebar mustache.

http://www.wsj.com/articles/SB10001424052970204778604577239583270202816
 
WIederling
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Re: Winglets On a A380

Thu Sep 08, 2016 7:29 pm

Matt6461 wrote:
I think this is backwards: the A320 probably already had more lift on the outboard sections than the 737.

A320:
http://www.fzt.haw-hamburg.de/pers/Scho ... schoot.pdf p36
B737ng:
http://aviation.stackexchange.com/quest ... cient-than ( near the end graphic borrowed from b737.org.uk

more lift further out on the wing will create a larger vortex. ( wingtip works as a "short circuit" for the lifting pressure differential.)
you either give the wing more span ( which will load the center wingbox significantly ) or you add winglets of in one form or other ( which also increases center wingbox loading but less so )

A wing with more outboard lift like that 737 graphic suggests ( "donut" comes to mind ) will gain much more than one with a more elliptical lift distribution.
Gives credence to Airbus arguing that the fences are good enough for the purpose and that winglets on the 737 were easy gains
while on the A320 the design objective was much more demanding.
 
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Matt6461
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Re: Winglets On a A380

Fri Sep 09, 2016 6:30 am

WIederling wrote:
wingtip works as a "short circuit" for the lifting pressure differential.


This seems incorrect per my reading of the best explanations. There are many faulty interpretations of induced drag reduction out there, especially around wingtip devices. See the following video at 34:39, for example: http://www.youtube.com/watch?v=QKCK4lJLQHU

The presenter discusses a a patent for a wingtip device that "straightens" the flow at the wingtips, eliminating the local vortices. Per the usual conception of tip vortices, as well as the inventor's, this local vortex elimination would pretty much eliminate induced drag as well. Problem is it doesn't actually work. The reason, says the presenter, is that the vortex field - the phenomenon of induced drag generally - is much larger and more complex than imagined if envisioning simple tip vortices. One has to look at the whole flow field across the span, not merely at the tips. The only way to reduce induced drag is to change that flow field; the only way to eliminate it is to have no flow (i.e. no lift).

WIederling wrote:
http://aviation.stackexchange.com/quest ... cient-than ( near the end graphic borrowed from b737.org.uk


The graphics you reference show induced drag reductions being associated with greater outboard lift distribution. So it seems to support my point...

Image
Last edited by Matt6461 on Fri Sep 09, 2016 6:51 am, edited 1 time in total.
 
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Matt6461
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Re: Winglets On a A380

Fri Sep 09, 2016 6:44 am

WIederling wrote:
wingtip works as a "short circuit" for the lifting pressure differential.


See also Bjorn Fehrm's discussion of the MC-21's new wing at Leeham:

The wing does not have any winglet or raked wingtips. This is no sign of not knowing how to do such devices. A common misunderstanding is that a winglet or raked tip increases a wing’s efficiency by affecting the wingtip vortices. This is a misconception.
Wing tip devices are part of the overall wing design and they improve the wing’s drag characteristics by forming a wider and (ideally) more elliptical lift distribution. If you achieve your target lift distribution with your base wing within the gate width restrictions you have, you don’t need the complexity of a special wingtip.


https://leehamnews.com/2016/02/08/irkut ... -analysis/
 
WIederling
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Re: Winglets On a A380

Fri Sep 09, 2016 7:40 am

You are good at misinterpreting others when it suits your agenda, right?
 
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Matt6461
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Re: Winglets On a A380

Fri Sep 09, 2016 8:01 pm

WIederling wrote:
You are good at misinterpreting others when it suits your agenda, right?


There's no room for interpretation here, let alone misinterpretation.

Here's what you said:

Balerit wrote:
lift distribution influences the tip vortex, the expensive large and complex winglets work better on a stronger vortex.


Here's what Bjorn said:

Matt6461 wrote:
A common misunderstanding is that a winglet or raked tip increases a wing’s efficiency by affecting the wingtip vortices. This is a misconception.


This is painfully obvious to any rational observer.
You claim wingtip devices work by impacting tip vortices; I claim (I adopt Bjorn's claim) that they work by shifting lift distributions outward.

You're wrong; Bjorn's right.

You have causation backward, as the video lecture I linked discusses. You cannot significantly decrease induced drag solely by manipulating a tip vortex; you have to look at the whole field and change lift distribution, span, and/or both. A wing with a distribution that is outboard-loaded absent a wingtip device will not benefit much from such a device - that's Bjorn's whole point about the MC-21 wing lacking such a device. Your contention that lesser A320 benefit from winglets/sharklets evinces [b]less[b] outboard lift is, therefore, entirely backward.

No amount of obfuscation with personal attacks makes that less so.
Were I not something of an A.net vet by now, I might be surprised and disheartened by your belligerent response to a purely analytical question. I know better. Still, I'll always repeat a simple, naive entreaty: just admit when you're wrong, learn something. My ego is entirely disconnected from any need to prove my knowledge on this forum; it's regrettable that yours is so fragile that a personal attack ensues from what should be a fun, interesting discussion. That video lecture, after all, imputes fundamental wrongness to large of swaths of indisputably brilliant people. Everyone can learn.
 
SCAT15F
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Re: Winglets On a A380

Mon Sep 19, 2016 10:55 pm

Exactly what would happen if Airbus decided to simply exceed the 80m box for wingspan and install proper A350 style winglets? What would that mean for an airport set up to handle the A380 already? Boeing has already (late 90's) proposed 747 variants that exceeded the 80x80 box...
 
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Starlionblue
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Re: Winglets On a A380

Tue Sep 20, 2016 12:36 am

SCAT15F wrote:
Exactly what would happen if Airbus decided to simply exceed the 80m box for wingspan and install proper A350 style winglets? What would that mean for an airport set up to handle the A380 already? Boeing has already (late 90's) proposed 747 variants that exceeded the 80x80 box...


Gate and taxiway space are the constraints. On taxiways, airports would need to further restrict movements while a 380 is taxiing, and gates might have to be widened.

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