Common Cathay question,

[Gumby]

Just out of curiosity, after hunting down many plausible answers and many arguments to the different variations.......

Why are the winglets (wing fences) on the A380 similar to those on the A319, 20, and 21? Why not use the raked winglets used on the A330/340?

Not that I have an interview, I would just like to know for my own sake.

[AMM]

Its my opinion that winglet design is far from an analytical method.

There may be a few models which use sets of coefficients (fudge factors) to define the broad design parameters, but in the end it comes down to CFD and some tunnel tests. Wing characteristics (taper ratio, sweep, twist, the spanwise variable airfoil etc.) are what end up defining the winglet much more the the overall size of the fuselage. And it may just be that the 380 wing is more closely related to that of the 320 series rather then the 340/330. But that's just my opinion.

[DEFPOTEC]

actually for the Cathay interview if they they ask you a question about airbus the correct answer is: (shake your head and say) - "who knows what airbus is thinking, ask me a boeing question"...works every time!

[L1011]

I imagine ground-handling was pretty big deciding factor too. Winglets would increase the wingspan even further on the A380, whereas a wing-tip fence would not.

[alti2d]

Aerodynamics for Naval Aviators ought to give you some insight into the answer. A little slogging through that will either give you the answer, or teach you never to ask the question again.

As to the previous comment, winglets are often used in the design to effectively reduce the wingspan of an aircraft by improving the aerodynamic efficiencies and interrelationship of airflow and the wingtip vortices.

http://www.amazon.com/Aerodynamics-Nava ... 156027140X

[LegoMan]

Winglets on the A330/A340 are not raked, the ones on the 777-300ER/-200LR, 767-400, 787 series and new 747-800 are.