Quoting Coal (Reply 9): After takeoff from Sydney, there was a significant amount of wind and, to my surprise, we were rattled about as though we were in much, much smaller plane, like a turboprop.

Well my understanding is Airbus wings are stiffer and the surface area is incredible, and that can lead to more turbulence than say a 777 which has very flexible wings. But I've also been in a 777 that was tossed about for 3 hours near the Berring Strait.

Another thing that may work against the A380 is that it is shorter than it is wide. I remember as a kid the 747SP flights and how there was a lot of yaw in turbulence due to this. The massive vertical stabs of the A380 and 747SP are there for a reason, to try to prevent that, but even they can only do so much.

I'd still imagine the A380 will roll through smaller bumps more smoothly because of it's mass/inertia.

I flew a a320 last month and if it did have a "active turbulence compensation system" it wasn't working.  

Basically it's not the size of the aircraft, it's the wing loading that matters. The higher the wing-loading (ie the amount of lift required per square foot) the more stable the aircraft is in turbulence. The A380 actually has a relatively low wing-loading vs something like a 777-300ER, because the A380's wing is huge and has been designed to cope with very much higher gross-weight, stretched versions (ie A380-900, -1000 etc). So I wouldn't necessarily expect the A380 to fare better in turbulence than existing aircraft.

Quoting 7cubed (Reply 11): flew a a320 last month and if it did have a "active turbulence compensation system" it wasn't working.

That system works great for little turbulence, not for heavy turbulence.

The A380 is so mighty that turbulence runs away when it sees it coming.

Signed,
Chuck Norris.

The A380 also has more broadside fuselage and empennage area making it more sensitive to lateral perturbations than say, the 777 or 747. And the wing is huge, basically designed to carry the stretched version of the plane as well as the present offering. I believe these factors would probably negate the added inertia it opposes to turbulence.

Faro

Quoting Khobar (Reply 5): As for FBW, that is only an interface that translates flight control inputs to the flight control surfaces. Old fashioned cables and pulleys do exactly the same thing, and accelerometers can feed either system. FBW has the advantage of being lighter and more easily maintained - that is its real advantage in large, lumbering commercial airplanes as it can save money.

FBW does not work just replacing cables. In analog, a move on the yoke means a proportional movement on the aerodynamic surfaces. With FBW, computers read the input of the pilots, and based on the flight conditions, choose the best position of the actuators. Even if you introduce other measuring systems to the analog control system, you won't get the complexity you can get with FBW. So they don't do exactly the same. FBW has many advantages which cables and pulleys obviously lack.

Quoting Khobar (Reply 5): And size doesn't seem to matter either considering the number of injuries that have happened on 747's.

Size actually does matter, and in this case, bigger is better. It really all comes down to Newtons laws here, where Force equals Mass times Acceleration, if turbulent air applies an equal force on two aircraft, one a cessna and one an A380, the object with the smaller mass will have a greater acceleration component, where the object with the larger mass will see a greatly reduced comparative acceleration. Also, bigger aircraft that are relatively stable in turbulence do experience more wing loading than lighter aircraft that get tossed around.

Quoting Graphic (Reply 17): Force equals Mass times Acceleration, if turbulent air applies an equal force on two aircraft, one a cessna and one an A380, the object with the smaller mass will have a greater acceleration component,

That is very true but you also have to look at that given a certain amount of wind the wind can apply more force to an A380 because the A380 is bigger. Size does matter to an extent but not just size, but also aerodynamics. It isn't as simple as a force being applied is equal, because it very rarely if ever is. The larger airplane has more force applied for a given wind and it is going faster and it is generally aerodynamically less stable than say a cessna.

Quoting Neverest (Thread starter): A topic that I have not seen discussed on this forum is how the A380 reacts to turbulence. I think as a general rule, the bigger an aircraft the less susceptible it is to turbulence. Therefore on this score the A380 should be quite stable and comfortable, encouraging many people to fly who otherwise put off flying. Do people who traveled on the plane have any observations?

I think the bigger the airplane is the less the turbulence but to an extent. Bigger airplanes have big wings and big wings give more oppertunity to be tossed around by bad air. The 747 is a huge plane but it can also get rocked by turbulence just as any other airplane can.

Quoting Prebennorholm (Reply 2): All Airbus FBW planes have the active turbulence compensation system, from the 318 and up. Vertical acceleration sensors give input to the flight control software which calculates small, but very fast movements of ailerons and spoilers smoothen the ride in turbulence.

That probably helps but I don't think that would do anything against dips.

Quoting Keta (Reply 16): FBW does not work just replacing cables. In analog, a move on the yoke means a proportional movement on the aerodynamic surfaces. With FBW, computers read the input of the pilots, and based on the flight conditions, choose the best position of the actuators. Even if you introduce other measuring systems to the analog control system, you won't get the complexity you can get with FBW. So they don't do exactly the same. FBW has many advantages which cables and pulleys obviously lack.

I said FBW "is only an interface that translates flight control inputs to the flight control surfaces. Old fashioned cables and pulleys do exactly the same thing." I stand by that statement.

You are confusing FBW and EFCS. It is the EFCS which provides the additional capability you refer to. To make the point, Airbus have what's called "Direct Law" which bypasses the EFCS (e.g. in the event of a royal screwup) and transmits the pilot control inputs unmodified to the control surface actuators.

I hope they can't totally eliminate it in the future. I actually like turbulence, makes the flight more interesting; like it's a long roller coaster ride that most people don't want to be on.

Before you go any further, you have to define turbulence.
It happens when one flies into an area of unstable air...it happens in gusty conditions...and basically it is caused by vertical and/or horizontal shifts in the ambient air.
Now consider :
1/- horizontal gusts. The effect on an airplane is dependant on the ratio of the gust speed to the aircraft TAS. So the faster the airplane, the less perceived the movement (associated with the *load factor* ). Therefore, an airliner is less susceptible than a light plane travelling slower.
2/- vertical gusts. here the effect depends -as been said in an earlier post- on the wing loading (the higher the W/S, the less the effect of the gust), AND the TAS (the higher the speed, the higher the load factor).
That said, the above applies to rather high g loads.
For just a *bumpy* ride, you'd have to consider
a/- the aircraft inertia
b/-the elasticity of the whole airplane, particularly the wings.On this aspect, ikramerica doesn't seem to have ever seen the wing flex of an A330 or 340 during takeoff.
c/-the damping systems of the airplane, beginning with the yaw damper which takes good care of transient lateral gusts and the *active control*, *gust alleviation systems* pioneered by Dassault on the Mercure and Lockheed on the Tristar 500 and present on Airbus products.

I will still take the 744 any day in heavy turbulence. I have seen a video once on Discovery Channel which shows the wings of the 747 flapping around like butterflies and it claims that they are designed to take the stress.

Quoting Khobar (Reply 20): You are confusing FBW and EFCS. It is the EFCS which provides the additional capability you refer to. To make the point, Airbus have what's called "Direct Law" which bypasses the EFCS (e.g. in the event of a royal screwup) and transmits the pilot control inputs unmodified to the control surface actuators.

I see what you mean. I was not confusing them, I just can't think of FBW without EFCS, because I call FBW the whole system, not just the replaced cables. I think you should have referred to this whole system on your original post, because that's how FBW airplanes work.

Quoting Khobar (Reply 5): Bottom line - listen to the FA at the beginning of the flight - keep your seatbelt fastened at all times unless you really need to unfasten it for some reason. You really won't like the view from the ceiling.

The view itself from the ceiling is probably OK, Khobar, just it tends to be rather transient and immediately followed by the much inferior view from the floor!!

Other that the difficulty of responding completely to turbulence, is there a particular aspect of the problem with the A380 due to its very large wings. Presumably they compensate better for very local changes, but might be more sensitive to larger disturbances. Against which would be the smoothing effects of the inertia due to the high mass of the beastie. ??

Quoting Neverest (Thread starter): A topic that I have not seen discussed on this forum is how the A380 reacts to turbulence. I think as a general rule, the bigger an aircraft the less susceptible it is to turbulence. Therefore on this score the A380 should be quite stable and comfortable, encouraging many people to fly who otherwise put off flying. Do people who traveled on the plane have any observations?

LOL. One or two years ago, the discussion board was full with literally hundreds of threads regarding the A380 wake turbulence. Just do a search and take a few free days   

I flew from Sydney to Singapore on the SIA 380 on the 8th November. There was some very light turbulence during the flight and the Airbus handled it much better than other aircraft I have flown on. Overall the airvraft also seemd much quieter . I fly to Asia and/or Europe from New Zealand most months for business and the A380 has been my best longhaul experience so far.

Quoting Keta (Reply 24): I see what you mean. I was not confusing them, I just can't think of FBW without EFCS, because I call FBW the whole system, not just the replaced cables. I think you should have referred to this whole system on your original post, because that's how FBW airplanes work.

Not entirely correct, Keta. You are thinking of the Airbus architecture in which the airplane systems tend to maintain the demanded g-load factor against all influences other than control inputs. Khobar, he thinks of the Boeing solution in which pilot (auto or live-) inputs mean flight control angle changes. (all preceding very roughly considered).

Quoting Warren747sp (Reply 23): I have seen a video once on Discovery Channel which shows the wings of the 747 flapping around like butterflies and it claims that they are designed to take the stress.

They all do, my friend.

Quoting Baroque (Reply 25): ther that the difficulty of responding completely to turbulence, is there a particular aspect of the problem with the A380 due to its very large wings. Presumably they compensate better for very local changes, but might be more sensitive to larger disturbances.

from what I said before, you'd have to consider that in theory, the lower wing loading of the A380 should make it more sensitive to vertical currents. OTOH, its inertia should damp most of the transients ( the perceived turbulence is actually a change in the wing lift due to the apparent change in AoA in a vertical gust. Now, going back to the earlier post mentioning forces and acceleration and you'll get accel = Lift / mass.... as mass is rather high, the acceleration should be less than on a lighter plane.
To quantify all this is about impossible for lack of data on airplane period, stiffness, wing/fuselage coupling...etc...

Quoting Keta (Reply 24): I see what you mean. I was not confusing them, I just can't think of FBW without EFCS, because I call FBW the whole system, not just the replaced cables. I think you should have referred to this whole system on your original post, because that's how FBW airplanes work.

Clearly FBW can exist without EFCS so, no, it is not "how FBW airplanes work". You might as well argue the autopilot is "how airplanes work".  

It's called gust alleviation and all Airbus's....(Airbi ?) have it.

There are people on here that will say it doesn't matter what size of plane your in, it's up to the strength of the turbulence as it puts force on the fuselage, wings, and control surfaces.

One would generally tend to think two things:

1. The complete surface area of a widebody, say and A380 or 747-400 is much more than a turboprop, thus the impact of the turbulent air on it would be greater seeing as the turbulence has more surface area to affect.

2. Bigger aircraft require more force to emmulate the feeling of the same type of movement significant turbulence would cause in a small turboprop because of the sheer size and weight of the aircraft.

While I think both of these lines of thought are in some ways correct, I also think that it has to do with many other factors as well, such as wing rigidity, surface control reactions, and where you are sitting on the aircraft.

I am personally one who things that sitting in the rear of the aircraft gives you more movement back there from turbulance. Why? Because there are 3 control surfaces at the very end of the plane that turbulence can affect both horizontally and vertically, not to mention you will also get the turbulence coming from the wingtips, throughout the wing to the fuselage.

For instance, to simulate aerodynamic forces on an airplane, simply make a small paper airplane, put a string on the nose, and blow. you will notice that any turbulent movements will be more severe toward the rear of the plane. Same sort of principle applies to true aircraft.

Also, the rigidity of the wings probably has something to do with it as well. In my opinion, th 747-400 wings are far more "floppy" (if you will) than the 757. They are longer and will generally spread out the effect of the turbulence in a larger area of the wing at which point the energy from the turbulence is spread so far out and through the wing, that it doesn't affect the fuselage as much as a 757's wings would. I've flown hundreds of thousands of miles on widebody and narrow body jets, and I can honestly say the "feeling" of turbulence is much different on a widebody with long, less rigid wings than say on a 737.

Flying from DFW-ICN on a 747-400 through some dense and heavy thunderstorms in north texas and oklahoma was like riding in a very very smooth car with very loose suspension. The plane's wings at the tips were flopping up and down probably 5-8 feet each way, but it felt like ripples inside the aircraft.

Something that I also find is that on aircraft like the MD-11, MD-80, etc, where the wing is set further back along the fuselage, there tends to be less turbulence affect in a greater percentage of the cabin (ie, forward of the wings).

These are just my observations, but I used to be VERY scared of turbulence so I was always making observations about how turbulence affects aircraft and what it feels like.

Small Planes + Rigid Wings = Porsche Suspension

Widebody + Long Floppy Wings = Lincoln Town Car/Lexus LS460 (Take your pick).

Oh, and BTW, The A380 has a triple slotted aileron system (not sure the technical name for it), but if you watch any A380 window view videos, you will see these ailerons in high action on the aircraft. Their movements as a set of 3 don't tend to make much sense while you are watching them, as sometimes the middle one goes straight up and the others go down, or do different things the same time. The 777 also has a turbulence alleviation system in some form or fashion with its inboard ailerons, as the outboard ailerons lock out after certain speeds. I think the 767, MD-11, DC-10, and L-1011 also have some sort of similar system with their inboard ailerons.

Only Airbus A310/300 have inboard ailerons, the rest all have outboard. Will be interesting to see how Boeing rigs it on the 787 as it only has outboard ailerons.


UAL

Quoting Hodja (Reply 7): Airplanes can't dodge turbulence. The sky controls the sky.

At least not with compensation technology. Indications are that more sophisticated radar systems (I think based on doppler) will map the sky and the turbulence likelyhood quite accurately. Combining that with free flight will make moderate turbulence a lot less likely.

Quoting UAL747 (Reply 31): These are just my observations, but I used to be VERY scared of turbulence so I was always making observations about how turbulence affects aircraft and what it feels like.

I'm the same way. You know, I'd love a "turbulence simulator." Something I could go into and have emulate a variety of different turbulence for me...so I could become more accustomed to it.

All the flights I've taken recently have been fairly smooth, and in spite of a few tranquilizers, I'm still sitting on edge of my seat wondering if something's going to happen.

Quoting UAL747 (Reply 31): The 777 also has a turbulence alleviation system in some form or fashion with its inboard ailerons, as the outboard ailerons lock out after certain speeds. I think the 767, MD-11, DC-10, and L-1011 also have some sort of similar system with their inboard ailerons. Only Airbus A310/300 have inboard ailerons, the rest all have outboard. Will be interesting to see how Boeing rigs it on the 787 as it only has outboard ailerons.

Unlike the other aircraft you listed the L-1011 inboard and outboard ailerons are active in all flight conditions (flaps up/flaps down, takeoff/cruise/landing). In fact the left inboard aileron actually controls the other three.

Quoting 474218 (Reply 33): Unlike the other aircraft you listed the L-1011 inboard and outboard ailerons are active in all flight conditions (flaps up/flaps down, takeoff/cruise/landing). In fact the left inboard aileron actually controls the other three.

Actually, most modern aircraft have "drooping flaperons" if you want a term for it. Didn't know the L1011's worked during all phases of flight. What about the 727's and 707's?

I still wish someone could give me definite answer on why the drooping inboard ailerons on the 777 always droop, then as thrust is applied, they are pushed up, and about halfway down the runway, they force themselves back into the drooping position. I know that is when the system kicks in, but why so late into the take-off roll?



UAL

Quoting Jimbobjoe (Reply 32): All the flights I've taken recently have been fairly smooth, and in spite of a few tranquilizers, I'm still sitting on edge of my seat wondering if something's going to happen.

The last flight I had over the Pacific going westward was complete hell in terms of turbulence. It was DFW-NRT on a 777. When it gets bumpy, I always raise my window shade for some reason. I like to see out. This is why I always want a window seat because the unexpected movement without seeing it relative to your surroundings always freaks me out. It's like riding a roller-coaster in complete darkness, you never know when you are going to take a dive.

UAL

Quoting Scbriml (Reply 14): The A380 is so mighty that turbulence runs away when it sees it coming. Signed, Chuck Norris.

Ahh yes..The Famous Chuck Norris Factoids   

Here's a great video of the 3 slotted aileron action on the A380. Watch the ailerons, especially close to touchdown.



UAL

Quoting Remcor (Reply 21): I hope they can't totally eliminate it in the future. I actually like turbulence, makes the flight more interesting; like it's a long roller coaster ride that most people don't want to be on.

Agree totally. Why not get the monies worth? We pay to take a roller coaster, why not enjoy the thrills on board.

Quoting Dazeflight (Reply 26): One or two years ago, the discussion board was full with literally hundreds of threads regarding the A380 wake turbulence.

But they were about the wake turbulence created by the A380 and its impact on other airplanes. This thread is about the atmospheric turbulence created by Mother Nature and the effect it has on the A380.

Quoting UAL747 (Reply 34): I know that is when the system kicks in, but why so late into the take-off roll?

To give the freestream dynamic pressure time to increase, lessening the effect of the turbulent engine exhaust on the flaperon.

I must be a total Debbie Downer... I can't seem to get what all the excitement on the A380 is about? This totally SUCKS!!   I mean, I am an aviation enthusiast, and I want to fly on it, but it depresses me that I am not as excited as I could be.