The A380 wing. A complex work of art!

The A380 wing is a remarkable piece of engineering. Made in Broughton, North Wales, it is one of the defining features of the A380. The largest wing used on a commercial aircraft before the A380 was designed belonged to the Boeing 747-400. It has a wingspan of 64.9 metres. Consequently, most major airports have been designed with this wingspan in mind. The A380 wing changed the rules! With a maximum takeoff weight of 575 tonnes, some 178 tonnes greater than the 747-400, a much larger wing was required.

This photograph clearly shows the much larger wing of the A380 compared to the 747.

The A380 has a wingspan of 79.676m and an area of 845.8m². Compare that to the wing of the 747-400 which has an area of 541.2m². And we should remember that the 747-400 is a very large aircraft. Trivia fans will note this means there is space to park 144 cars on each side of the the A380 wing!

Each A380 wing has 3 ailerons, 8 spoilers, 8 slats and 3 flaps.

These are terms you may well have heard before. But if not, what does each one mean?

Ailerons – These are used mainly at low speed (below 240 knots) to make the aircraft bank (or roll) from side to side. They move in opposite directions on each wing. Therefore, if we want the aircraft to bank left, the ailerons on the left wing will move up and those on the right will move down. This has the effect of dropping the left wing and raising the right wing. The ailerons on the A380 are also used as part of an active system to reduce the effect of turbulence. More of that later… Each aileron has a maximum deflection of 20° down and 30° up.

Spoilers – These are only on the upper surface of the wing. They have several uses. Firstly, the outer 6 spoilers are used for roll control at higher speeds. In this case, only the spoilers on one wing will move, with a maximum deflection of 45°. Secondly, all 8 spoilers on each wing can be used as speed brakes. You may have seen the spoilers on an aircraft rise during descent. They effectively reduce the lift from the wing and act as air brakes, useful if we want to slow down or go down more rapidly. This will be accompanied by a slight rumbling feeling inside the aircraft. Nothing to worry about. But if ever you have felt it, now you know why!

Their final function is to ‘dump’ the lift from the wing on landing to prevent the aircraft going back into the air. Cleverly, this ground spoiler function has two phases. When one main landing gear is sensed as having touched down the ground spoilers partially extend (spoilers 1 and 2 by 10° and 3 to 8 by 15°. This slightly reduces the lift produced by the wing and aids in a gentle touchdown. Once three main landing gears are sensed on the ground the spoilers extend fully (1 and 2 to 35°, 3 to 8 up to 50°). The ailerons also deflect upwards to 25° acting as additional spoilers and air brakes.  This movement of the spoilers and ailerons will also occur if a rejected takeoff is performed from a speed greater than 72 knots.

Slats and Flaps – Slats and flaps provide lift augmentation. Simply put, aircraft wings are designed to work best at their cruising speed. But we wouldn’t want to try and land the aircraft at that speed! The normal wing shape has a range of operating speeds, but even on superb design such as the A380, this will not be below around 190 knots at landing weight, and more like 230 knots at takeoff weight. In order to allow the aircraft to fly at lower speeds during takeoff and landing the shape of the wing has to be changed. In order to do this there are various stages of slats (front or leading edge of the wing) and flaps (rear or trailing edge) which can be extended.

For those interested in the technical working of these systems, the A380 slats are moved by an electric motor and a hydraulic motor whereas the flaps are driven purely by hydraulic motors. If you have flown on an A380 you will quite probably have heard a quite high pitched ‘whining’ noise when the slats move. It is these motors which generate that noise.

Airbus aircraft use a standard set of slat/flap configurations which depend on flight phase and speed. Convention is that we always ask for a flap setting rather than a slat and flap setting. This is true on Boeing and Airbus aircraft. We ask for the required flap setting knowing that the slats will also move to a corresponding setting. The slats and flaps are controlled using a lever on the centre console between the pilots.

For takeoff, the A380 has three possible slat/flap positions (known as configurations). These are 1, 2 and 3. We action a takeoff performance calculation using one of the apps installed on the aircraft in order to determine the best flap setting for each individual takeoff. There are several factors to consider here. Flap 1 gives the highest takeoff speeds and greatest after takeoff climb gradient, but due to the higher speed needed before takeoff uses more runway. Flap 3 gives the lowest speeds for takeoff but also a reduced initial climb gradient because in addition to producing more lift at lower speeds, flap 3 also produces more drag. For landing we can use Flap Full or Flap 3. In most cases flap 3 is used.

The angle of slat and flap extended for each configuration is shown in the table below.

What is aileron droop? In certain configurations the A380 extends the ailerons down on both wings by 5° in order to provide additional low speed lift, effectively turning them into small flaps.

You will notice that there are two possible configurations when the flap lever is in position 1. When we select flap 1 on the ground as a takeoff flap setting, we get 20° of slat extension and 8° of flaps. This is called configuration 1+F (one plus F). We always have some flap extension for takeoff. However, when we are in flight and reducing speed for our initial approach, there may be a time when we only want the slats to be extended in order to allow a reduction in speed below our ‘minimum clean’ speed, the minimum speed at which we can fly with the wing in the normal shape. Having slats only extended in this case allows us to fly slightly slower than our minimum clean speed, but not get the additional drag which would be produced by the flaps. This would typically happen if we were relatively heavy and air traffic control asked us to maintain a speed of 210 knots. Our minimum clean speed could be around 220 knots, but extending flap 1 (which actually wouldn’t give us any flap at all, just slats to 20°) would allow us to fly at 210 knots. When we subsequently reduce speed below 205 knots, the flaps auto extend to 8°. This is the AES (Automatic Extension System)

You will see from the table that each configuration has a maximum speed. We need to be mindful of this when making flap selections. In addition to the AES we also have the wonderfully named ARS system! (Always raises a smile when we discuss it during takeoff briefings!) ARS = Automatic Retraction System. For higher weight takeoffs the speed at which we would normally retract the flaps setting from 1+F to zero can be close to the limiting speed of 222 knots. In this case, in order to protect the flaps from overspeed, the ARS automatically retracts them to zero leaving only the slats extended when the aircraft accelerates past 212 knots. Very clever!

The wings have one further vital function. They act as massive fuel tanks.

Each wing contains five fuel main fuel tanks, a surge tank, and a vent tank. The surge tanks temporarily collect fuel which may overflow from any tank when they are close to being full. For example, fuel may overflow a full tank during a tight turn while taxiing. The vent tanks connect the fuel tanks to exterior atmospheric pressure in order to limit the differential pressure between the tanks and the atmosphere.

The fuel tanks are huge! Each wing has a capacity of 149924 litres! That’s around 120 tonnes. The trim tank at the rear can hold 23698 litres, which is almost the same as the total fuel capacity of an A320! If you want to ‘fill-her-up’ you will need to put 323546 litres in the tanks.

One complication of making these amazing wings in North Wales is they have to be transported to the Airbus factory in Toulouse where the aircraft is assembled. This is a major logistical operation! A Multi-Purpose Vehicle is used to transport the wings on the 1.6km journey from the Broughton factory to the River Dee. This MPV is 22 metres long, has 96 wheels, and with the wing plus the carrying jig, carries around 140 tonnes. The MPV drives on board the Dee River Craft to place the wing in position for its 24km journey along the river to the Port of Mostyn. From here, another MPV collects the wings where they are put on the roll-on-roll-off ship Cuidad de Cadiz where they sail to Pauillac, the nearest port to Toulouse. On arrival in Pauillac they are transferred on to barges which transport them 95km up the Garonne river to Langon. From there the final 240km of the journey is by road.

The Langon to Toulouse journey passes through 21 towns and villages. Much of this journey is done at night to avoid disruption. I was lucky enough to be invited to the Airbus factory in Toulouse in April 2017. This included a visit to the nearby town of Levignac, through which the convoy passes. Although the particular convoy I saw didn’t have a wing shipment included, it did have some A380 fuselage sections. As you can see on the video below (click the link), the clearance between the fuselage and buildings in the town is rather small! I was informed the wing sections are slightly wider than this, resulting in even less room for manoeuvre!

A380 Convoy through Levignac

Finally, a few interesting facts about the A380 wing..

Each set of wings has 20 panels and 314 stringers. They contain 750000 rivets or bolts! And lots of wire – 23 miles of it!