A380 ailerons

[cawka]

As you probably know, A380's ailerons are divided into 3 segments. Could anyone explain the purpose(s) of it?

[Rainboe]

Not familiar with A380 flight controls, but one reason will probably be as with the 747. Outer wing ailerons are too powerful for high Mach No. cruise and would require outer wing stiffening. The 747 reverts, when flaps are retracted, to only inner ailerons, which conveniently can be placed in that space at the back of the wing behind the inner engine, where flaps cannot be placed. These inner ailerons alone are enough for roll control at high speed. The outer aileron in the A380 may be split into two for structural reasons and hydraulic redundancy.

[Clarence Oveur]

Since the A380 is FBW, I would suggest segmented ailerons are for redundancy only. I seem to remember that it has mixed hydraulic/electric powered controls.

[Dani]

not necessarily. One could argue that aileron produce wing twist, especially on big wings. So if you are able to spread the aileron force on different parts of the trailing edge of the wing, you could possibly reduce the load on the wing.

As Rainboe said, there are different types of aileron on bigger aircraft, not only for redundancy, but also for aerodynamic reasons. Smaller aircraft can coordinate a turn only with ailerons and a little rudder, the bigger and faster you get the more problems you encounter during a turn. FBW doesn't replace aerodynamics, it's just to move the control surfaces.

Dani

[Short_Circuit]

Please do not hang me on this one, however, from what I understand
as a non Airbus Avionic LAME is. :8

There are 3 ailerons per wing outboard of the flaps.
Each has 2 sources of power, hyd – hyd or hyd – elect/hyd (act with an elect pump generating it’s own internal Hyd power.
Each segment driven by dedicated actuator, commanded by a dedicated Flight Control Computer Primary & Secondary (PRIM 1,2 or 3 & SEC1, 2 or 3).
If one surface fails to operate correctly the other 2 can compensate by moving more or less to keep normal feel & control.

With all ailerons on the end of the wings, flight control inversion is probably of great concern, hence 3 separate control surfaces that
are able to modify their control output.

I would love to do a course, sounds like a cleaver A/C.

Can someone lend me $30,000.00 for the bond.:sad:

[Mephistopheles]

If it's anything like the A330/340 flight control system. Then the outer ailerons are only used at low speed or with th AP engaged or if failure cases.

[ARINC]

Please do not hang me on this one, however, from what I understand
as a non Airbus Avionic LAME is.
There are 3 ailerons per wing outboard of the flaps.
Each has 2 sources of power, hyd – hyd or hyd – elect/hyd (act with an elect pump generating it’s own internal Hyd power.
Each segment driven by dedicated actuator, commanded by a dedicated Flight Control Computer Primary & Secondary (PRIM 1,2 or 3 & SEC1, 2 or 3).
If one surface fails to operate correctly the other 2 can compensate by moving more or less to keep normal feel & control.
With all ailerons on the end of the wings, flight control inversion is probably of great concern, hence 3 separate control surfaces that
are able to modify their control output.


Good stab....However...

The inboard and mid ailerons are actuated by a servocontrol and an Electro Hydrostatic Actuator (EHA) in an active/stby arrangement. The Outboard ailerons are actuated by 2 servocontrols same active/stby arrangement.

Each actuator has two MAIN operating modes

1. Active mode acts on instructions from FCS
2. Damping Mode, prevents flutter if there are multiple system failures.

Each aileron is actuated by one actuator in Active mode and one in damping mode. Inboard and Mid ailerons are connected to one Primary and one Secondary computer

Outboards are connected to Primary com only.

Don't forget the Spoilers are also integrated via flight concentrator !
:ok:

[mavrik1]

The 380 has a newer generation technology again. The flight controls that have a low hyd fliud demand i.e. ailrons have their own hydraulic packages that have there own resivoir built in to the actuator that is linked to the control surface.
This means Airbus does not require to have any hyd lines routed to these distant locations thus saving weight, time, money, the actuator operates independant and the use of safer fliuds can be used i.e. 5606 mineral oil instead of synthetic skdrol ld-40 on these applications. If the actuator goes U/S it can be locked out and MEL applied or change component. All that will be attached to the componet is the electrical canon plug.
The 380 still has the original 3 hyd systems green, yellow, blue, which the computers will control in these configs therefore on aileron for each hyd system. For the aircrafts high fliud demand systems i.e. landing gear, the hyd sub system is the same as todays aircrafts.

Pro's:
- If one package starts leaking fliud it doesnt threaten the rest of the system.
- No hydraulic lines
- Save money on maintenance
- Safer fliud
- Less parts required.
Cons:
- system pressure 5000psi instead of 3000psi
- Mechanics have heaps more systems to top up with fliud instead of the original 3.

[cirrus01]

Hooray !..........less Skydrol :D

[Rainboe]

The VC10 back in the 60s had power control units at all flight controls, cable operated with self contained hydraulic systems at each individual surface. Quite spectacular in severe turbulence to see all low pressure warning lights on for every surface! With flaps up and 25,000', the outer ailerons floated up to offload lift from the outer wing to save wing bending.

[Chrome]

The 380 still has the original 3 hyd systems green, yellow, blue, which the computers will control in these configs therefore on aileron for each hyd system.


The A380’s flight controls are hydraulically powered as always. But there are only 2 hydraulic systems instead of 3. There are no more the Blue system. The Green and Yellow systems are powered by engine-driven pumps and operate at 5,000psi instead of the 3000psi the Green, Blue, Yellow system used in other aircraft in the Airbus family to reduce weight.

2 actuators move each of the 3 ailerons in a wing. The inboard and middle ailerons are moved by a hydraulic actuator and an electrohydrostatic actuator EHA but the outer aileron is moved by 2 hydraulic actuators.

The electrical backup hydraulic actuators EBHAs has replaced the Blue hydraulic system. It is these EBHAs (it combines hydraulic servocontrol and EHA functions in a single unit) that help operate and move the inboard and middle ailerons in an event of dual hydraulic loss so handling performance is not compromised. At high speeds the outer ailerons are locked out anyway in rolls.

[ARINC]

Chrome old chum...Already stated in post 7 above... :ugh::ugh: It helps to read the thread in it's entirety before posting..

[Chrome]

Yes I did read you post. I was just replying to mavrik1 and ranting further for the benefit of the guys who like you say do not read the thread in entirety :)

[Algy]

I had the privilege (http://www.flightglobal.com/blogs/flight-international/2007/02/first-media-flight-in-the-a380.html) of being SLF taking-off in an A380 on an exceptionally gusty / X-wind day in Toulouse and watching the extraordinary movements of the ailerons. Never really seen anything like it - surfaces moving very rapidly up to about half-travel and in opposition to each other. But a remarkably steady ride.

(How gusty? Here's a cockpit movie of that day's landing (http://www.flightglobal.com/articles/2007/02/08/211995/video-exclusive-footage-of-airbus-a380-msn007-landing-in-toulouse-from-the.html)- thread creep I realise, it's not compulsory.)