Ethan22
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Does the ailerons on the Airbus A220 droop because it is a fly-by wire aircraft?

Wed Aug 28, 2019 12:53 am

Does the ailerons and horizontal stabilizers on the A220 family droop due to the fact that the aircraft is a fly-by wire type?

Thanks
 
Weatherwatcher1
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Re: Does the ailerons on the Airbus A220 droop because it is a fly-by wire aircraft?

Wed Aug 28, 2019 12:56 am

Are we talking about on the ground or in the air?
 
Ethan22
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Re: Does the ailerons on the Airbus A220 droop because it is a fly-by wire aircraft?

Wed Aug 28, 2019 1:00 am

on the ground
 
Weatherwatcher1
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Re: Does the ailerons on the Airbus A220 droop because it is a fly-by wire aircraft?

Wed Aug 28, 2019 1:09 am

Most flight control surfaces droop when the hydraulics aren’t powered.
 
N757ST
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Re: Does the ailerons on the Airbus A220 droop because it is a fly-by wire aircraft?

Wed Aug 28, 2019 1:10 am

Weatherwatcher1 wrote:
Most flight control surfaces droop when the hydraulics aren’t powered.


On FBW airplanes they usually droop.
 
Ethan22
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Re: Does the ailerons on the Airbus A220 droop because it is a fly-by wire aircraft?

Wed Aug 28, 2019 1:10 am

thanks
 
Weatherwatcher1
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Re: Does the ailerons on the Airbus A220 droop because it is a fly-by wire aircraft?

Wed Aug 28, 2019 1:17 am

N757ST wrote:
Weatherwatcher1 wrote:
Most flight control surfaces droop when the hydraulics aren’t powered.


On FBW airplanes they usually droop.


It is somewhat independent of whether they are fly by wire or not. It depends on if the aileron is mass balanced or not. Ailerons on a 747 droop when not hydraulically powered, but the 747 isn’t fly by wire. It is true that fly by wire airplanes don’t usually have mass balanced ailerons since they are fully hydraulically powered.
 
loggat
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Re: Does the ailerons on the Airbus A220 droop because it is a fly-by wire aircraft?

Wed Aug 28, 2019 2:44 am

The ailerons droop when the flaps are deployed as a method of increasing lift. Part of the FBW system.

The elevators droop (actually positioned deliberately nose down) during the takeoff roll as the aircraft is inherently tail heavy. This increases nose wheel steering effectiveness during the takeoff.
There are 3 types of people in this world, those that can count, and those that can't.
 
Q
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Re: Does the ailerons on the Airbus A220 droop because it is a fly-by wire aircraft?

Wed Aug 28, 2019 2:48 am

I like this Yak-40 both ailerons were up. When the plane on the taxing the ailerons was shaking. If the plane taking off the ailerons will even flat when air pushing faster. It looks funny on YAK-40's. LOL You should look at youtube watch that ailerons.

Q
 
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777222LR
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Re: Does the ailerons on the Airbus A220 droop because it is a fly-by wire aircraft?

Wed Aug 28, 2019 3:01 am

What always puzzled me is that on the 777 and 787, the inboard ailerons droop way down as thrust is applied at take off. As the plane goes down the runway, they go up, almost too high, then further down the runway, they droop back to whatever flap setting is selected.
 
reltney
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Re: Does the ailerons on the Airbus A220 droop because it is a fly-by wire aircraft?

Wed Aug 28, 2019 4:46 am

loggat wrote:
The ailerons droop when the flaps are deployed as a method of increasing lift. Part of the FBW system.

The elevators droop (actually positioned deliberately nose down) during the takeoff roll as the aircraft is inherently tail heavy. This increases nose wheel steering effectiveness during the takeoff.



Lots of wrong info but in the right direction.

First thing is some planes droop ailerons when flaps are extended. While on some airliners with FBW the ailerons do droop, many airplanes have ailerons that droop with flap extension that do not have fly by wire. The list is to long to type but one we all know is the 767. Inboard ailerons droop with flap extension. I just flew a wren 460 and it had flaperons..ailerons drooped with flaps... twin otter is another ...

Second wrong info...elevators droop as the aircraft is “inherently” tail heavy...NOT. It would never be certified!!! tail heavy planes are not part of the airline fleet. Go do research as the explanation is too long to type here. Airbus has a dorky procedure where they hold elevator nose down on the beginning of their takeoff roll. Lots call BS and I have seen many hold nose up and as I was on a United jumpseat last week, the capt held full nose up as he applied the power and released it around 80 kits to prove it was an unnecessary procedure... go figure...

Cheers...
Knives don't kill people. People with knives kill people.
OUTLAW KNIVES.

I am a pilot, therefore I envy no one...
 
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DocLightning
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Re: Does the ailerons on the Airbus A220 droop because it is a fly-by wire aircraft?

Wed Aug 28, 2019 5:13 am

777222LR wrote:
What always puzzled me is that on the 777 and 787, the inboard ailerons droop way down as thrust is applied at take off. As the plane goes down the runway, they go up, almost too high, then further down the runway, they droop back to whatever flap setting is selected.


On the 777 and 787, hydraulics to the ailerons are put into bypass mode when thrust is first applied to the engine so as not to stress the actuators and increase their fatigue life. At a certain speed (I think 50 knots), the ailerons switch to deflect fully up, so that they do not block or deflect the engine thrust while still reducing stress on the actuator. At 100 knots, the ailerons revert to flight mode.
-Doc Lightning-

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godsbeloved
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Re: Does the ailerons on the Airbus A220 droop because it is a fly-by wire aircraft?

Wed Aug 28, 2019 12:29 pm

reltney wrote:
loggat wrote:
The ailerons droop when the flaps are deployed as a method of increasing lift. Part of the FBW system.

The elevators droop (actually positioned deliberately nose down) during the takeoff roll as the aircraft is inherently tail heavy. This increases nose wheel steering effectiveness during the takeoff.



Lots of wrong info but in the right direction.

First thing is some planes droop ailerons when flaps are extended. While on some airliners with FBW the ailerons do droop, many airplanes have ailerons that droop with flap extension that do not have fly by wire. The list is to long to type but one we all know is the 767. Inboard ailerons droop with flap extension. I just flew a wren 460 and it had flaperons..ailerons drooped with flaps... twin otter is another ...

Second wrong info...elevators droop as the aircraft is “inherently” tail heavy...NOT. It would never be certified!!! tail heavy planes are not part of the airline fleet. Go do research as the explanation is too long to type here. Airbus has a dorky procedure where they hold elevator nose down on the beginning of their takeoff roll. Lots call BS and I have seen many hold nose up and as I was on a United jumpseat last week, the capt held full nose up as he applied the power and released it around 80 kits to prove it was an unnecessary procedure... go figure...

Cheers...
Great captain on that flight...

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prebennorholm
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Re: Does the ailerons on the Airbus A220 droop because it is a fly-by wire aircraft?

Thu Aug 29, 2019 1:49 am

reltney wrote:
Airbus has a dorky procedure where they hold elevator nose down on the beginning of their takeoff roll. Lots call BS and I have seen many hold nose up and as I was on a United jumpseat last week, the capt held full nose up as he applied the power and released it around 80 kits to prove it was an unnecessary procedure... go figure...

United flies mostly north of the Equator where last week it was summer. Likely there wasn't much snow or ice on the runway combined with strong crosswind.

My car also has almost a dozen stabilization features which never activated over 100,000 miles. It doesn't mean that one of them might not be helpful one day next winter.
Always keep your number of landings equal to your number of take-offs
 
loggat
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Re: Does the ailerons on the Airbus A220 droop because it is a fly-by wire aircraft?

Mon Sep 02, 2019 4:07 am

reltney wrote:
Lots of wrong info but in the right direction.

First thing is some planes droop ailerons when flaps are extended. While on some airliners with FBW the ailerons do droop, many airplanes have ailerons that droop with flap extension that do not have fly by wire. The list is to long to type but one we all know is the 767. Inboard ailerons droop with flap extension. I just flew a wren 460 and it had flaperons..ailerons drooped with flaps... twin otter is another ...

Second wrong info...elevators droop as the aircraft is “inherently” tail heavy...NOT. It would never be certified!!! tail heavy planes are not part of the airline fleet. Go do research as the explanation is too long to type here. Airbus has a dorky procedure where they hold elevator nose down on the beginning of their takeoff roll. Lots call BS and I have seen many hold nose up and as I was on a United jumpseat last week, the capt held full nose up as he applied the power and released it around 80 kits to prove it was an unnecessary procedure... go figure...

Cheers...


I am an A220 pilot, so the information I posted is not just general aviation conjecture. I was actually relaying the reasons that the ailerons and elevators are positioned where they are based on the systems training knowledge that I have for the A220.

Bombardier designed the ailerons to "droop" to aid in lift and to distribute wing loading more effectively with the flaps down. This is a feature of the A220's FBW system. My previous aircraft was the 767 so I am familiar with the inboard aileron droop there as well. I never said the ailerons drooped because it has FBW, I said it is a feature of the FBW system for the A220.

As for the elevators, as I originally said, the CG balance of the aircraft is inherently towards the aft (tail heavy). It is very common for us to load ballast in the forward cargo. The aircraft is obviously not designed to be tail heavy where it falls on its tail, but I assume you are aware there are takeoff CG envelopes, and it just so happens that the A220 generally has an aft CG. I'm sure I also don't need to explain the pros and cons of an aft versus forward CG, but for the those that don't know, an aft CG is often considered a positive situation during cruise flight as it relates to fuel consumption, so there are always tradeoffs. So assuming that Bombardier deemed it better to have a more aft CG, they designed, as part of the A220 FBW system, a method to compensate for any unwanted nose-up tendencies during the takeoff roll by deflecting the elevators down to force a nose-down force, which in turn keeps more force on the nose wheel for more effective nose wheel steering during the takeoff. Again, this is a feature of the FBW system of the A220. The pilot does not have to hold the sidestick forward for this to occur. The Primary Flight Control Computers perform this function in the normal flight mode automatically.

Having never flown the A320, it wouldn't be prudent for me to comment on the FBW system and what you saw on the United jumpseat.
There are 3 types of people in this world, those that can count, and those that can't.
 
DashTrash
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Does the ailerons on the Airbus A220 droop because it is a fly-by wire aircraft?

Tue Sep 03, 2019 4:52 am

reltney wrote:
Second wrong info...elevators droop as the aircraft is “inherently” tail heavy...NOT. It would never be certified!!! tail heavy planes are not part of the airline fleet. Go do research as the explanation is too long to type here. Airbus has a dorky procedure where they hold elevator nose down on the beginning of their takeoff roll. Lots call BS and I have seen many hold nose up and as I was on a United jumpseat last week, the capt held full nose up as he applied the power and released it around 80 kits to prove it was an unnecessary procedure... go figure...

Cheers...


The Citation X is a tail heavy, transport category aircraft. Full down elevator from the start of the takeoff roll, full down elevator after de-rotating on landing and before opening the buckets or you risk a tail strike.


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GalaxyFlyer
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Re: Does the ailerons on the Airbus A220 droop because it is a fly-by wire aircraft?

Tue Sep 03, 2019 8:52 pm

You all have to define “tail heavy”. All Part 25 planes have to exhibit stable pitch characteristics, no F-16 style relaxed static stability allowed. Lots of planes have on the ground tail strike characteristics—B757 can be forward “heavy” and derotate hard, lots of planes have little leeway for tail strikes, opening steel TRs can effectively move the CG aft. None of these are tail heavy.

GF
 
reltney
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Re: Does the ailerons on the Airbus A220 droop because it is a fly-by wire aircraft?

Wed Sep 25, 2019 2:46 am

If a plane is tail heavy vs a plane at the aft end of the w&b envelope. This is where the non pilot is confused. Tail heavy in all pilot circles means the plane is beyond the aft limit of the CG. When it stalls, the nose will go up. Not cool. Only plane know to have a normal CG aft is an F-16. Airliners...NOT. It is an instability which has not been built in an airliner today.

Galaxy flyer is correct 100%
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Starlionblue
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Re: Does the ailerons on the Airbus A220 droop because it is a fly-by wire aircraft?

Wed Sep 25, 2019 9:32 am

reltney wrote:
If a plane is tail heavy vs a plane at the aft end of the w&b envelope. This is where the non pilot is confused. Tail heavy in all pilot circles means the plane is beyond the aft limit of the CG. When it stalls, the nose will go up. Not cool. Only plane know to have a normal CG aft is an F-16. Airliners...NOT. It is an instability which has not been built in an airliner today.

Galaxy flyer is correct 100%


Not only the F-16. Most modern fighters have at least "relaxed" stability.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
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DocLightning
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Re: Does the ailerons on the Airbus A220 droop because it is a fly-by wire aircraft?

Thu Oct 10, 2019 3:03 am

777222LR wrote:
What always puzzled me is that on the 777 and 787, the inboard ailerons droop way down as thrust is applied at take off. As the plane goes down the runway, they go up, almost too high, then further down the runway, they droop back to whatever flap setting is selected.


For the Boeing flaperon, when thrust is first applied, the hydraulics to the flaperon are shut off, so they drop down all the way. As thrust increases, they "float" up on the thrust and then they are actively deflected to full up. After 80 knots, then they are returned to normal mode. This function serves to increase the fatigue life on the actuator mechanisms.
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