I would like to know how I can approximate the additional area added to wing on flaps 1+F: image of the area I want

Can someone use other dimensions they know of the A380 wing and approximate what this area would be, we can say that these 3 sections are rectangular and we can also add 20% to estimate the area added by slats which we can't see in the video.

It would be ideal if I knew the chord length and then I could use the logger pro software to find the width of the rectangle but I have been unable to find this data, even from Airbus because the A380 project is closed.

link to video:

Please someone help me, with this information I will able to do all the maths I am doing using related rates to model the rate of change of lift of an A380 after take-off (basically this additional area will help me get dA / dt where A is area and t is time, it's useful because its a related rate to lift as Planform area is in the lift equation.)

I have tried for days and not been able to get this number, I would appreciate any assistance from you online folks. Even any approximate number is useful please, just get me a reasonable number and also explain how you did it.


1 Answer 1


You're coming at this wrong. Fortunately, the world is more simple than you're trying to make it.

Although the wing area can be considered to change (when flaps are deployed), the wing reference area is held constant.

$L = C_L\,q\,S_\mathrm{ref}$

So, the effect of flaps is actually absorbed into the definition of the lift coefficient. If you think of $C_L$ as a function, it is a function of...

$C_L=f(\alpha,M,Re, \mathrm{Config})$

Angle of attack, Mach, Reynolds number, and Configuration -- i.e. flap position.

If you look closely at $C_L$ vs. $\alpha$ data for a fowler flap system, you will see that there is an apparent increase in the lift curve slope. That isn't really what has happened -- instead, it is really due to the increase in chord, but (for 2D data) the reference chord is left alone.

There is still a zero-lift angle, but for every degree, the airfoil with a longer chord gets more lift. So this shows up as an increase in lift curve slope.

If you have detailed aerodynamic data for clean vs. flaps (lift curves and drag polars), then you can certainly use that during your takeoff / landing model.

Usually, the flap position does not change during the takeoff or landing ground roll.

For an aircraft performance and sizing perspective, we treat the deployment of flaps as instantaneous and ignore any time it would take.

I suppose if you were developing a detailed flight simulator and you knew an aircraft had a slow flap deployment/retraction, you could interpolate between the data tables as the flaps move -- but I don't think anyone would include a $\frac{d \delta_\mathrm{flap} }{dt}$ term.


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