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A340 Ailerons Drooping When Flaps Set  
User currently offlineHappy-flier From Canada, joined Dec 1999, 299 posts, RR: 0
Posted (6 years 5 months 1 week 6 days 2 hours ago) and read 12471 times:

I've seen lots of photos of A340 (and I suppose A330 as well) wings in takeoff and/or landing configuration where not only are the flaps down, but the outer aileron sections are as well. I'm sure aerophysicists knew what they were doing when designing these systems - but I can't quite place the sense of it in my mind: doesn't aileron deflection that far out on the wing basically just bend the wingtips up? Is there much significant lift gained by doing this? You certainly never saw this on the L1011, DC-10 or even the 767 (though the inner ailerons do droop down on the 767).

And, the other question: Can an A340 pilot elect to just use the flaps, and leave the ailerons in neutral position - or does the outer aileron drooping happen by default?


May the wind be always at your back . . . except during takeoff & landing.
54 replies: All unread, showing first 25:
 
User currently offlineLongHauler From Canada, joined Mar 2004, 4913 posts, RR: 43
Reply 1, posted (6 years 5 months 1 week 6 days 2 hours ago) and read 12496 times:

Aileron droop, has been a feature of Airbus aircraft since the A300.
They still work as ailerons, just from a different datum.

No, the pilot has no control over aileron droop.



Never gonna grow up, never gonna slow down .... Barefoot Blue Jean Night
User currently offlineCosmicCruiser From United States of America, joined Feb 2005, 2255 posts, RR: 15
Reply 2, posted (6 years 5 months 1 week 5 days 20 hours ago) and read 12425 times:

The MD-11 has them as well but ours were disabled due to high maint issues.

User currently offlineFlyASAGuy2005 From United States of America, joined Sep 2007, 7004 posts, RR: 11
Reply 3, posted (6 years 5 months 1 week 5 days 19 hours ago) and read 12411 times:

This sounds interesting. Could you provide a link so I can see this in action?


What gets measured gets done.
User currently offlinePlaneWasted From Sweden, joined Jan 2008, 515 posts, RR: 0
Reply 4, posted (6 years 5 months 1 week 5 days 19 hours ago) and read 12411 times:



Quoting CosmicCruiser (Reply 2):
The MD-11 has them as well but ours were disabled due to high maint issues.

Interesting. For the Airbus it probably means no extra maintenance because the Ailerons are controlled through the FBW systems.


User currently offlineStarlionblue From Greenland, joined Feb 2004, 16999 posts, RR: 67
Reply 5, posted (6 years 5 months 1 week 5 days 19 hours ago) and read 12408 times:

The 777 also has aileron droop, but since it's a Boeing the surfaces are referred to as flaperons.

Quoting PlaneWasted (Reply 4):
Interesting. For the Airbus it probably means no extra maintenance because the Ailerons are controlled through the FBW systems.

That doesn't follow. Maintenance is on the actuators, flap tracks and such. What initiates the droop seems irrelevant.



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlinePlaneWasted From Sweden, joined Jan 2008, 515 posts, RR: 0
Reply 6, posted (6 years 5 months 1 week 5 days 18 hours ago) and read 12378 times:

But the MD11 probably has some dedicated hardware for the droop, while the Airbus is just software. or..?
Just guessing here.


User currently offlineSeabosdca From United States of America, joined Sep 2007, 5312 posts, RR: 4
Reply 7, posted (6 years 5 months 1 week 5 days 14 hours ago) and read 12319 times:



Quoting FlyASAGuy2005 (Reply 3):
This sounds interesting. Could you provide a link so I can see this in action?


View Large View Medium
Click here for bigger photo!

Photo © Alexandre Dubath
View Large View Medium
Click here for bigger photo!

Photo © Andres Contador



Look around the database for photos of A330 and A340 aircraft in initial climb and on short final and you'll find quite a few more like these.


User currently offlineSlamClick From United States of America, joined Nov 2003, 10062 posts, RR: 68
Reply 8, posted (6 years 5 months 1 week 5 days 14 hours ago) and read 12310 times:

Airbus certainly didn't invent the concept.


View Large View Medium
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Photo © Dan Barnes
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Photo © Jonathan Rankin



Quoting CosmicCruiser (Reply 2):
disabled due to high maint issues

Wonder if there is a performance penalty. They do contribute life.
Anyone have a CDL?



Happiness is not seeing another trite Ste. Maarten photo all week long.
User currently offlineHappy-flier From Canada, joined Dec 1999, 299 posts, RR: 0
Reply 9, posted (6 years 5 months 1 week 5 days 10 hours ago) and read 12243 times:

Another thought: Why didn't the 727 use a similar aileron-droop system? It had a clean wing with no engine appendages, so at the very least they could have used the inboard ailerons to augment short-field takeoffs.

Anyone know if the 727 could do that?



May the wind be always at your back . . . except during takeoff & landing.
User currently offlineOldAeroGuy From United States of America, joined Dec 2004, 3476 posts, RR: 67
Reply 10, posted (6 years 5 months 1 week 5 days 9 hours ago) and read 12217 times:



Quoting Starlionblue (Reply 5):
The 777 also has aileron droop, but since it's a Boeing the surfaces are referred to as flaperons.

The 777 flaperon (ie inboard aileron/flap) is different than a drooped aileron. When extended to act as a flap, it has both Fowler motion and opens a slot, becoming a single slotted flap. Dropped ailerons have no Fowler motion and don't open a slot as they articulate via a simple hinge.

777 outboard ailerons droop when flaps are extended and are referred to as (wait for it!) dropped ailerons.



Airplane design is easy, the difficulty is getting them to fly - Barnes Wallis
User currently offlineJetlagged From United Kingdom, joined Jan 2005, 2543 posts, RR: 24
Reply 11, posted (6 years 5 months 1 week 5 days 8 hours ago) and read 12188 times:



Quoting SlamClick (Reply 8):
Airbus certainly didn't invent the concept.

Good to see you back in the forum.  thumbsup 

Quoting Happy-flier (Reply 9):
Anyone know if the 727 could do that?

No aileron droop on a 727. They probably had enough complication in that wing without that.



The glass isn't half empty, or half full, it's twice as big as it needs to be.
User currently offlineStarlionblue From Greenland, joined Feb 2004, 16999 posts, RR: 67
Reply 12, posted (6 years 5 months 1 week 5 days 7 hours ago) and read 12168 times:



Quoting PlaneWasted (Reply 6):
But the MD11 probably has some dedicated hardware for the droop, while the Airbus is just software. or..?
Just guessing here.

Yeah maybe. But I don't really think the assemblies would be that different.



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineThrottleHold From South Africa, joined Jul 2006, 655 posts, RR: 1
Reply 13, posted (6 years 5 months 1 week 5 days 7 hours ago) and read 12167 times:

The 330/340 outboard ailerons droop by 5' when the flaps are deployed to enhance lift.

User currently offlinePrebennorholm From Denmark, joined Mar 2000, 6387 posts, RR: 54
Reply 14, posted (6 years 5 months 1 week 5 days 6 hours ago) and read 12141 times:

I don't think there are any FBW airliners out there without some sort of aileron droop. And that includes all current production Airbusses from 318 to the 380. It's a quite simple addition to flight control software which boosts slow speed performance a little.

It does, however, give a serious adverse yaw tendency when operating the drooped ailerons as ailerons. But at least the Airbussses (don't know about B777 and MD-11) have automatic rudder compensation for adverse yaw. You simply don't touch the pedals in flight until you have to make a landing in sidewind.

As far as I know the MD-11 is the only non-FBW airliner with aileron droop.

My model aeroplanes also have aileron droop, which I can disable with a switch on the R/C transmitter. That's needed since I don't have automatic adverse yaw compensation.

Competition gliders have had fully mechanical aileron droop for decades, but in a slightly different way. The ailerons follow the flaps when only activated a few degrees for maximising cruise performance. When flaps are lowered beyond a certain angle, and becomes as much brakes as lift generators, then the ailerons go back to neutral again for improved roll control, and also to keep adverse yaw within sensible limits. Some gliders even give negative droop on the ailerons when flaps are fully extended, which makes all four control surfaces work as mainly very efficient air brakes.



Always keep your number of landings equal to your number of take-offs, Preben Norholm
User currently offlineCosmicCruiser From United States of America, joined Feb 2005, 2255 posts, RR: 15
Reply 15, posted (6 years 5 months 1 week 4 days 21 hours ago) and read 12037 times:



Quoting Starlionblue (Reply 5):
That doesn't follow. Maintenance is on the actuators, flap tracks and such. What initiates the droop seems irrelevant

That's what I meant, thanks for wording it better. The A/C status page of the FMS would show drooped ailerons so I'm sure it was FMC generated. I never experienced any yaw on T/O or cruise or any other unfavorable flight characteristics. If you didin't see it on the FMS it would transparent.

Quoting SlamClick (Reply 8):
Wonder if there is a performance penalty. They do contribute life.
Anyone have a CDL?

I believe it would have been fuel burn penalty but not enough to justify the maint. I just tried looking it up in the MD-11 CFM but it looks as it's been deleted from our books. If I were at home I have an older CFM that I could reference if anyone is interested let me know.


User currently offlineFlyASAGuy2005 From United States of America, joined Sep 2007, 7004 posts, RR: 11
Reply 16, posted (6 years 5 months 1 week 4 days 19 hours ago) and read 12023 times:

Still no pic?

Anyone? I won't know what to look for if I try to go through the database.



What gets measured gets done.
User currently offlineBuyantUkhaa From Mongolia, joined May 2004, 2871 posts, RR: 3
Reply 17, posted (6 years 5 months 1 week 4 days 19 hours ago) and read 12018 times:



Quoting Happy-flier (Thread starter):
but I can't quite place the sense of it in my mind: doesn't aileron deflection that far out on the wing basically just bend the wingtips up?

So what? It would still be a force acting on the plane as a whole, so even if it would bend the wings up it would not "disappear" .



I scratch my head, therefore I am.
User currently offlinePhilSquares From , joined Dec 1969, posts, RR:
Reply 18, posted (6 years 5 months 1 week 4 days 19 hours ago) and read 12013 times:



Quoting Prebennorholm (Reply 14):
It does, however, give a serious adverse yaw tendency when operating the drooped ailerons as ailerons. But at least the Airbussses (don't know about B777 and MD-11) have automatic rudder compensation for adverse yaw. You simply don't touch the pedals in flight until you have to make a landing in sidewind.

Not on the 320. If you have an engine failure prior to engaging the autopilot, you will have to use rudder just like a conventional aircraft. Once the autopilot is engaged, it will compensate for adverse yaw.


User currently offlineJetlagged From United Kingdom, joined Jan 2005, 2543 posts, RR: 24
Reply 19, posted (6 years 5 months 1 week 4 days 19 hours ago) and read 12006 times:



Quoting Prebennorholm (Reply 14):
As far as I know the MD-11 is the only non-FBW airliner with aileron droop.

The Airbus A300, A310 and A300-600 all have aileron droop. The Boeing 767 has inboard aileron droop.



The glass isn't half empty, or half full, it's twice as big as it needs to be.
User currently offlineStarlionblue From Greenland, joined Feb 2004, 16999 posts, RR: 67
Reply 20, posted (6 years 5 months 1 week 4 days 18 hours ago) and read 11995 times:



Quoting BuyantUkhaa (Reply 17):
Quoting Happy-flier (Thread starter):
but I can't quite place the sense of it in my mind: doesn't aileron deflection that far out on the wing basically just bend the wingtips up?

So what? It would still be a force acting on the plane as a whole, so even if it would bend the wings up it would not "disappear" .

Actually wing bending does have an effect. Say the right aileron goes down and the left goes up (roll left). If the wings bend enough, the effect does "disappear". The wing bend acts as a control force in the opposite direction. So on the right wing, the aileron goes down, but the up bent and twisted wing acts like an aileron going up.



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineJetlagged From United Kingdom, joined Jan 2005, 2543 posts, RR: 24
Reply 21, posted (6 years 5 months 1 week 4 days 18 hours ago) and read 11987 times:



Quoting PhilSquares (Reply 18):
Not on the 320. If you have an engine failure prior to engaging the autopilot, you will have to use rudder just like a conventional aircraft. Once the autopilot is engaged, it will compensate for adverse yaw.

Same for the A330 and A340. The flight control system computes a beta target, it's up to the pilot to follow it if autopilot is not engaged.



The glass isn't half empty, or half full, it's twice as big as it needs to be.
User currently offlineDavid L From United Kingdom, joined May 1999, 9523 posts, RR: 42
Reply 22, posted (6 years 5 months 1 week 4 days 18 hours ago) and read 11979 times:



Quoting Starlionblue (Reply 20):
Actually wing bending does have an effect. Say the right aileron goes down and the left goes up (roll left). If the wings bend enough, the effect does "disappear". The wing bend acts as a control force in the opposite direction. So on the right wing, the aileron goes down, but the up bent and twisted wing acts like an aileron going up.

Hence the reason that outboard ailerons are often locked out at higher speeds, if fitted at all. However, can we assume that at those speeds where the flaps are deployed, the wing twist isn't a significant factor?


User currently offlineCanadianNorth From Canada, joined Aug 2002, 3389 posts, RR: 9
Reply 23, posted (6 years 5 months 1 week 4 days 16 hours ago) and read 11949 times:



Quoting Prebennorholm (Reply 14):
As far as I know the MD-11 is the only non-FBW airliner with aileron droop.



Quoting SlamClick (Reply 8):
SlamClick

...


CanadianNorth



What could possibly go wrong?
User currently offlineDavid L From United Kingdom, joined May 1999, 9523 posts, RR: 42
Reply 24, posted (6 years 5 months 1 week 4 days 16 hours ago) and read 11931 times:



Quoting CanadianNorth (Reply 23):
Quoting SlamClick (Reply 8):
SlamClick

Does the Beaver count as an airliner?  Smile

Incidentally...

Quoting Jetlagged (Reply 11):
Good to see you back in the forum.

 checkmark  Ditto.


25 SEPilot : The 727, having totally mechanical flight controls, would have a much more difficult time implementing it than would FBW planes. Boeing probably figu
26 Jetlagged : FBW only affects how the controls are signalled, not how they are actuated. Aileron droop is used in many non FBW aircraft, see posts above. The 727
27 BuyantUkhaa : Well I was thinking in the context of drooped ailerons, meaning that the situation is symmetrical, and wing bending would not have much of an effect.
28 Starlionblue : Yes I see.
29 Post contains images 2H4 : Wren, for example: 2H4
30 OldAeroGuy : The effect was demonstrated in flight on the B-47 long before the advent of the 707. Control was not just lost, at high speeds it was reversed. If yo
31 FlyASAGuy2005 : Ok now I finally know what you guys are talking about! Thanks for indirectly helping me out 2H4
32 DeltaGuy : The F/A-18 Hornet's ailerons droop as well. DeltaGuy
33 Post contains images SEPilot : Thanks for the correction. My memory was somewhat hazy and I was recounting what I thought I recalled. Your post jogged my memory and you, as usual,
34 Prebennorholm : Thanks Jetlagged, I didn't know that also the A300/310 have aileron droop. The B767, isn't that somewhat different, and in fact identical to even the
35 Post contains images Jetlagged : No, and I don't think that's correct for the 707 or DC-8 either. Inboard ailerons always function as ailerons. The outboard ailerons are not so much
36 Arrow : Absolutely. I've been a paying passenger on many a Beaver flight, as well as Otters, Twin Otters. I'm pretty sure they all have flaperons, and in the
37 Post contains images David L : OK, let me rephrase: did Prebennorholm mean to include aircraft such as the Beaver in his comment?
38 Post contains images 2H4 : I'm still in awe that a designer with a name like that wound up working on an airplane called the "Beaver". As if there weren't enough innuendo possib
39 MD11Engineer : On the MD-11 the mechanism is actually quite simple: The rods connecting the outboard aileron bell cranks to the ailerons contain a screwjack and a s
40 Post contains images 9VSIO : The airbus ailerons don't just droop, they also deflect upwards on landing
41 Jetlagged : The only way they will deflect upwards is from a roll input.
42 2H4 : Ailerons and elevators aren't the only control surfaces that can deflect upward. Certain Maules and gliders have a negative seven degree flap setting.
43 Post contains images Soon7x7 : A340 Ailerons also double as spoilers, dumping lift upon runway contact...In fist photo of D-AIHO in a long decent, in stable air, you can see the con
44 Post contains images 9VSIO : Nope. There is a very clear "lift dump" mode Yeah, that's what I've been told by big bus drivers and I doubt that the a/c had a large roll input on t
45 Jetlagged : Certainly not on the A320, and I can find no reference to this in A340/A330 manuals. Are you not confusing this with ground spoilers? After all once
46 Post contains links David L : Not much evidence of lift-dumping ailerons here: 320: http://www.youtube.com/watch?v=xhCbfdrA1HE 330: http://www.youtube.com/watch?v=3aRLHIFTANA 340:
47 Post contains links and images Jetlagged : You learn something new every day! There are no spoilers in front of the ailerons so I guess Airbus decided additional braking and liftdumping from th
48 Post contains images David L : I confess I went searching for the videos whilst in Bollocks Mode, myself. I didn't think to check the 345/346 separately, though.
49 Soon7x7 : While Photographing these two configurations, both sides were in view and I was able to qualify symetry on both sides during two shots as I had never
50 Post contains images 9VSIO : No worries Jetlagged Same here actually, I quickly browsed an early A380 pilots guide and an A330/340 FCTM after my last post and all it talked about
51 Airbus_A340 : Our A340 manual says when spoilers extended deflection will be " [(A340)−600: 25° for inner and outer ailerons]. " regards
52 JoeCanuck : Thanks for that...though you may have cost me a keyboard...and a cup of coffee... I didn't see this mentioned so forgive me if it's a repeat. To enha
53 Jetlagged : Roll spoilers were used initially on jet airliners for high speed roll control because they don't twist the wing like an aileron does at high Mach No
54 JoeCanuck : That may very well be the case. I've only noticed roll spoilers when flaps are extended, though slower speeds is when they are easiest to notice due
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