A320 Flight Controls

[jesse]

Thanks a lot!

Will come back to back angle later!
Was thinking about this: Side sticks commands G load.

1 --> G load is the acceleration: how fast we want to increase /decrease pitch.
2 --> 2G :Twice our weight.

So let's say that full SS AFT = 2G.
How can you relate 1 and 2? Weight and speed?

In 1 sentence: Pulling Side-stick AFT = 1 + 2
How would you say it?

Sidestick back commands the airplane to increase pitch just like a traditional airplane. The difference is that the computer limits the amount of pitch up force applied so that 2.5Gs is never exceeded and 30 degrees pitch up is never exceeded.

 

[TheBusFlyer]

Yes, agreed .

Let me ask my questions like this:

1) When we pull the stick, we basically tell the computer how fast we want to increase/decrease pitch, right AND the rate of G we want to have, right?

2) If my pitch angle is NOT increasing/decreasing, then I am at 1g, right?

3) To maintain any G above/under 1g, the plane will have to keep increasing/decreasing pitch, right?

4) So stick is saying (e.g) it want's 2.5g. That is equal to the fastest pitch-up demand, right?

5) So lower the G, lower the speed at which pitch will increase, right?

Thanks

 

[Henning]

Yes, agreed .

Let me ask my questions like this:

1) When we pull the stick, we basically tell the computer how fast we want to increase/decrease pitch, right AND the rate of (,or; they are the same, you can't have 'rate of G) G we want to have, right?

Yes

2) If my pitch angle is NOT increasing/decreasing, then I am at 1g, right?

Yes

3) To maintain any G above/under 1g, the plane will have to keep increasing/decreasing pitch, right?

Yes

4) So stick is saying (e.g) it want's 2.5g. That is equal to the fastest pitch-up demand, right?

Yes

5) So lower the G, lower the speed at which pitch will increase, right?
Yes
Thanks

Only one small semantic correction this time.

 

[TheBusFlyer]

Thanks a lot iHenning!

You are just great!

So are we in a direct SS to Elevator between 1.3G and 2.5?

 

[Henning]

Thanks a lot iHenning!

You are just great!

So are we in a direct SS to Elevator between 1.3G and 2.5?

I can't answer that, I was just helping you conceptualize what you were relaying incorrectly. I do not know the system except from these threads.

 

[RotorAndWing]

So are we in a direct SS to Elevator between 1.3G and 2.5?

No...

 

[TheBusFlyer]

Why R&W?
I am not saying you are in direct law....

Are you still in normal law without trim?

Thanks

 

[Henning]

Why R&W?
I am not saying you are in direct law....

Are you still in normal law without trim?

Thanks

Why would you be without trim? You already dropped below 1.3G.

 

[Singlepilot]

Thanks a lot iHenning!



You are just great!



So are we in a direct SS to Elevator between 1.3G and 2.5?

No, in this scenario you are in a direct sidestick to flight control response between v alpha prot and v alpha max.

Above 1.25g the computers halt the auto trim function. 1.25g equates to 33 degrees of bank. The system is designed like this so that if you want to enter a normal turn you do not need to correct for the loss of the vertical component of lift as in a conventional plane. To turn you simply command the side stick left or right and the computers will adjust to maintain level flight. If you want to bank more than 33 degrees you will need to pitch up to maintain level flight just like in a conventional plane. The designers made it this way because a transport category aircraft should not "normally" need a bank angle exceeding 33 degrees. You can bank up to 67 degrees but they wanted to make you tactilely aware that you were doing so by needing to correct the pitch manually between 33 and 67 degrees.

The trim stops at V alpha prot for the same reason it's inhibited at low altitude. At slow speeds large amounts of trim are required to trim for neutral control response. Once you begin recovering and your airspeed starts rapidly increasing the trim rate lags the airspeed recovery and the aircraft is out of trim.


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[35 AoA]

Agree with the earlier post.....overthinking. There are a lot of common misconceptions of FBW/CBW flight control systems, I think mostly posed by guys that are too set in their ways to sit down and actually understand the system. Things like the "pilot is only a voting member". I can't speak specifically to the Airbus, but I do have a lot of experience in a digital control by wire aircraft, and there is no difference between flying it and any other conventional control aircraft.......other than the fact that it is much easier to fly, and does exactly what I want 100% of the time. You make a control input, the system interprets what it is that you want, and it makes a million more control surface inputs than a traditional aircraft to affect (effect?) that response. It also buffers out things like turbulence and can literally make up for some really ham fisted stick and rudder skills. 40 years later, this configuration is still getting a bad name from some, and it makes guys think "hmmmm this system is out to get me and I need to know how to trick it into doing what I want" which couldn't be further from the reality.

 

[Singlepilot]

Agree with the earlier post.....overthinking. There are a lot of common misconceptions of FBW/CBW flight control systems, I think mostly posed by guys that are too set in their ways to sit down and actually understand the system. Things like the "pilot is only a voting member". I can't speak specifically to the Airbus, but I do have a lot of experience in a digital control by wire aircraft, and there is no difference between flying it and any other conventional control aircraft.......other than the fact that it is much easier to fly, and does exactly what I want 100% of the time. You make a control input, the system interprets what it is that you want, and it makes a million more control surface inputs than a traditional aircraft to affect (effect?) that response. It also buffers out things like turbulence and can literally make up for some really ham fisted stick and rudder skills. 40 years later, this configuration is still getting a bad name from some, and it makes guys think "hmmmm this system is out to get me and I need to know how to trick it into doing what I want" which couldn't be further from the reality.

I totally agree. I love the FBW system and making the switch to it took all of about 15 minutes in the simulator to feel comfortable with it.


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[jesse]

Well to a degree, assuming the system is fully operational - the pilot is only a voting member in some scenarios. In those scenarios though that's probably a very good thing because the pilot's vote would have resulted in a BadThing happening.

 

[nauga]

...I do have a lot of experience in a digital control by wire aircraft, and there is no difference between flying it and any other conventional control aircraft.......other than the fact that it is much easier to fly, and does exactly what I want 100% of the time....40 years later, this configuration is still getting a bad name from some, and it makes guys think "hmmmm this system is out to get me and I need to know how to trick it into doing what I want" which couldn't be further from the reality.

I'm going to print this and frame it

Nauga,
from the inside

 

[TheBusFlyer]

Thanks,

I am not talking about bank now - only pitch!

What about AoA in all this?

When does that come? You are at 1G - 30° pitch.
Pitch protection comes ALWAYS before AoA protection?

Thanks

 

[Henning]

Thanks,

I am not talking about bank now - only pitch!

What about AoA in all this?

When does that come? You are at 1G - 30° pitch.
Pitch protection comes ALWAYS before AoA protection?

Thanks

I would think that AoA would overrule everything in Normal Law. Critical AoA is a compendium of effects including G and Pitch. So regardless to where you get in the other two limits, it will stop their progress before stall.

 

[Singlepilot]

TBF,

AOA protection has priority. Please see post 32. Depending on your speed and configuration it's possible to hit the AOA protection before the high pitch protection. An aircraft can stall at a low pitch but at its critical angle of attack.

With respect, I'm not sure what your background is but this system has been explained thoroughly in this thread. I think you are having some issues understanding the basic aerodynamics involved. Without this understanding the FBW architecture is never going to make sense to you.


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[Henning]

TBF,

AOA protection has priority. Please see post 32. Depending on your speed and configuration it's possible to hit the AOA protection before the high pitch protection. An aircraft can stall at a low pitch but at its critical angle of attack.

With respect, I'm not sure what your background is but this system has been explained thoroughly in this thread. I think you are having some issues understanding the basic aerodynamics involved. Without this understanding the FBW architecture is never going to make sense to you.


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I think he's a high school student trying to learn what the school isn't teaching. It looks like he got the cart a bit in front of the horse. I think you're right, a quick halt on the Airbus book and a bit of basic study on Aerodynamics and the physics of flight, and these systems would be much easier to comprehend. They're difficult enough to understand if you know what they're needing to manage and why. Without that understanding, it's nigh an impossible task.

 

[TheBusFlyer]

Good evening,

Yes - all your predections are right - I am a school student.

Well, let me recap for vertical side-stick movents - please correct me If I am wrong.

When we pull the stick, we basically tell the computer how fast we want to increase/decrease pitch, also called G Load.
If my pitch angle is NOT increasing/decreasing, then I am at 1g. To maintain any G above/under 1g, the plane will have to keep increasing/decreasing pitch.
So stick is saying (e.g) it want's 2.5g. That is equal to the fastest pitch-up demand. So lower the G, lower the speed at which pitch will increase.

In the Airbus FBW system, you have pitch angle protection = 30° Configuration Clean.
So at a certain point, you will not be able to increase G, as the pitch angle will no more increase. It means that you will be at 1g.

Now you also have pitch trim - it maintains the current aircraft's pitch at 1G.
It doesn't work over 1.3G and under 0.5G. But even if you release the stick, with a G > 1.3G, the aircraft will maintain the current pitch angle because it would have gone back to 1G (Aircraft is no more pitching).

AoA has the priority. The plane can hit Aprot at a low pitch angle.

Am I right?

Thanks a lot,
TBF

 

[Singlepilot]

TBF,

What kind of school program are you in and how does this thread on advanced FBW systems specific to the Airbus relate to what you are studying?


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[TheBusFlyer]

No, it is just for passion.
It is not at all helping me for school...

Thanks to help (isn't it right?)

Have a nice sunday,
TBF

 

[Dr. O]

FBW is high technology in the cockpit. The pilot can yank the stick around and the aircraft will limit transient G loads to a limit to protect the airframe from bending/breaking, from accelerated stalls, yadda, yadda.
He can initiate a turn with only stick motion and the FBW will hold altitude and keep the ball centered. And so on. Basically, the pilot can point the nose of the plane and then relax and drink coffee.

The real question I have is after 20 years (or whatever) of this can he fly an airplane?

Now, the question is not sarcasm or a sense of my (god given) superiority as a pilot. I cannot step into the cockpit of a high technology airliner (or fighter) and fly it. Likely I cannot even get the displays to turn on much less select the correct screens, etc. I cannot do these things because I have not been trained on the system. The pilot of one of these technological marvels is managing a complex system.

The question is can that highly trained manager of complex technology still do basic stick and rudder flying.
Sully proved he could - probably because of his continued light airplane/glider flying.
The French and Malysian pilots (some) have proven they cannot - when they stall the airframe and hold it in stall from 6 miles up until the impact.

Now, all of this drivel is the build up to a question. That question is should airline pilots, besides doing the sim training in type every 6 months (or whatever) have to also strap on a BE55 and take it around the patch a few times to be considered current? .

 

[Henning]

Good evening,

Yes - all your predections are right - I am a school student.

Well, let me recap for vertical side-stick movents - please correct me If I am wrong.

When we pull the stick, we basically tell the computer how fast we want to increase/decrease pitch, also called G Load.
If my pitch angle is NOT increasing/decreasing, then I am at 1g. To maintain any G above/under 1g, the plane will have to keep increasing/decreasing pitch.
So stick is saying (e.g) it want's 2.5g. That is equal to the fastest pitch-up demand. So lower the G, lower the speed at which pitch will increase.

In the Airbus FBW system, you have pitch angle protection = 30° Configuration Clean.
So at a certain point, you will not be able to increase G, as the pitch angle will no more increase. It means that you will be at 1g.

Now you also have pitch trim - it maintains the current aircraft's pitch at 1G.
It doesn't work over 1.3G and under 0.5G. But even if you release the stick, with a G > 1.3G, the aircraft will maintain the current pitch angle because it would have gone back to 1G (Aircraft is no more pitching).

AoA has the priority. The plane can hit Aprot at a low pitch angle.

Am I right?

Thanks a lot,
TBF

One mistake, > is Greater than, < is less than, that's it.

 

[RotorAndWing]

Now, all of this drivel is the build up to a question. That question is should airline pilots, besides doing the sim training in type every 6 months (or whatever) have to also strap on a BE55 and take it around the patch a few times to be considered current? .

What would that have to do with proficiency? What is so dramatically different in flying a Baron around the traffic pattern and flying an Airbus around a traffic pattern? How would this attribute to basic airmanship skills?

 

[Greg Bockelman]

What would that have to do with proficiency? What is so dramatically different in flying a Baron around the traffic pattern and flying an Airbus around a traffic pattern? How would this attribute to basic airmanship skills?

Yeah, that. I have the same questions.

 

[Clark1961]

What would that have to do with proficiency? What is so dramatically different in flying a Baron around the traffic pattern and flying an Airbus around a traffic pattern? How would this attribute to basic airmanship skills?

FBW with maybe too many protections vs fully mechanical controls...hmmm, can't think of a single dramatic difference there...

 

[RotorAndWing]

FBW with maybe too many protections vs fully mechanical controls...hmmm, can't think of a single dramatic difference there...

So explain why flying one around the pattern is dramatically different than flying the other?

We are talking normal take off, normal climb, turning climb, straight and level, descent, descending turn, final descent and landing, landing rollout and stopping.

And please explain how having mechanical controls versus FBW should make any difference from the pilot's perspective. Can he really tell the difference?

 

[Fearless Tower]

What would that have to do with proficiency? What is so dramatically different in flying a Baron around the traffic pattern and flying an Airbus around a traffic pattern? How would this attribute to basic airmanship skills?

Nothing. You can do basic VFR pattern work in the sim (of the plane you fly at work) just as well as you can in a piston twin.

 

[Clark1961]

So explain why flying one around the pattern is dramatically different than flying the other?

We are talking normal take off, normal climb, turning climb, straight and level, descent, descending turn, final descent and landing, landing rollout and stopping.

And please explain how having mechanical controls versus FBW should make any difference from the pilot's perspective. Can he really tell the difference?

Perhaps you should ask a couple pilots who arrived just a little short at SFO? Perhaps you should ask three pilots who precipitated an Airbus in the middle of the Atlantic? Oh, that's right, you can't ask them 'cause they are dead.

Perhaps you should ask yourself why you are being deliberately obtuse?

 

[Henning]

FBW with maybe too many protections vs fully mechanical controls...hmmm, can't think of a single dramatic difference there...

I've gotten to fly the 777 and A320 sim, and I didn't really notice any difference in basics and nothing dramatic at all in normal flight regimes. FBW limiters only come into effect when you are at max or minimum performance parameters, which doesn't really change anything except how the controls can be manipulated by just holding them to full and just let the plane fly it on the edge rather than physically finessing it. At least that was the only difference I noticed in "basic airmanship". You still think the same way, you just have different options of how to manipulate the controls.

 

[RotorAndWing]

Perhaps you should ask a couple pilots who arrived just a little short at SFO? Perhaps you should ask three pilots who precipitated an Airbus in the middle of the Atlantic? Oh, that's right, you can't ask them 'cause they are dead.

Perhaps you should ask yourself why you are being deliberately obtuse?

It's clear you don't have a clue as to what you're writing about (what's new? ) and are only interested in turning a discussion into a pizzing match.

 

[Clark1961]

It's clear you don't have a clue as to what you're writing about (what's new? ) and are only interested in turning a discussion into a pizzing match.

So the guys who arrived short at SFO didn't have a problem with automation? The guys who dropped the Airbus into the ocean knew how to recognize and recover from a stall? Wow, guess their victims weren't really injured/killed. Just keep denying and you'll be fine.

Yup, I don't know a damn thing.

 

[Henning]

Perhaps you should ask a couple pilots who arrived just a little short at SFO? Perhaps you should ask three pilots who precipitated an Airbus in the middle of the Atlantic? Oh, that's right, you can't ask them 'cause they are dead.

Perhaps you should ask yourself why you are being deliberately obtuse?

Neither of those were the fault of the FBW system, rather a lack of understanding the system which flying a Baron would not help with. With AF the FBW system gave them every possible chance, that thing flew a dead perfect falling leaf stall, as commanded, right to the water. Flying a Baron again would do nothing, who the **** practices stalls in a Baron? If you lack the capacity to continue to think and act in an emergency, it doesn't matter what training you had. That crash is an indictment of the pilot selection and qualifying for captain, not an indictment of FBW.

 

[Henning]

So the guys who arrived short at SFO didn't have a problem with automation? The guys who dropped the Airbus into the ocean knew how to recognize and recover from a stall? Wow, guess their victims weren't really injured/killed. Just keep denying and you'll be fine.

Yup, I don't know a damn thing.

How does a lack of knowledge of an automated system unique to a type get served by training in a plane of a different type that doesn't have the system? How is it a failing of 'basic airmanship' that would have been cured by training in a Baron?

 

[RotorAndWing]

So the guys who arrived short at SFO didn't have a problem with automation? The guys who dropped the Airbus into the ocean knew how to recognize and recover from a stall? Wow, guess their victims weren't really injured/killed. Just keep denying and you'll be fine.

Yup, I don't know a damn thing.

At least you got one thing right.

 

[RotorAndWing]

How does a lack of knowledge of an automated system unique to a type get served by training in a plane of a different type that doesn't have the system? How is it a failing of 'basic airmanship' that would have been cured by training in a Baron?

Clark just trolling for an argument, nothing of any substance.

 

[Clark1961]

At least you got one thing right.

And you still don't have a single thing right.

Instead of dismissing perhaps you should try explaining your point of view. Explain to yourself how automation and protections are different from manual controls. Explain to yourself the differences in training for the different systems and what is required of the pilot. Once you've gone through those excercises perhaps then you can come back here and behave reasonably rather than dismissively. Then again, perhaps not.

The other thing going on here is that old saw about doing the same thing repeatedly and expecting a different outcome. In this thread there is a suggestion of doing something different in an effort to improve the outcomes. Instead of looking at the proposal critically you simply dismiss it with obtuse questions. Perhaps instead of being dismissive you should weigh the pros and cons. I think that you can't do that because you see it as a suggestion from outside the system and you see the system as good enough. I know that nearly all systems need improvement and all too frequently those inside the systems can't see or accept the need.

So to wrap it up, no I'm not looking for an argument - that is what you do. I'm looking for some unbiased analysis from folks who claim to be experts. Remember that being trained to fly an aircraft has nothing to do with being trained to improve systems or even in being trained in how to improve the training itself.

 

[RotorAndWing]

And you still don't have a single thing right.

Instead of dismissing perhaps you should try explaining your point of view. Explain to yourself how automation and protections are different from manual controls. Explain to yourself the differences in training for the different systems and what is required of the pilot. Once you've gone through those excercises perhaps then you can come back here and behave reasonably rather than dismissively. Then again, perhaps not.

The other thing going on here is that old saw about doing the same thing repeatedly and expecting a different outcome. In this thread there is a suggestion of doing something different in an effort to improve the outcomes. Instead of looking at the proposal critically you simply dismiss it with obtuse questions. Perhaps instead of being dismissive you should weigh the pros and cons. I think that you can't do that because you see it as a suggestion from outside the system and you see the system as good enough. I know that nearly all systems need improvement and all too frequently those inside the systems can't see or accept the need.

So to wrap it up, no I'm not looking for an argument - that is what you do. I'm looking for some unbiased analysis from folks who claim to be experts. Remember that being trained to fly an aircraft has nothing to do with being trained to improve systems or even in being trained in how to improve the training itself.

I'm not arguing with someone who clearly doesn't even begin to understand what's being discussed.

Go find someone else to play your silly games with Clark. You're simply not worth the wasted effort.

And have a nice day! :wink2:

 

[nauga]

FBW with maybe too many protections vs fully mechanical controls...hmmm, can't think of a single dramatic difference there...

There are quite a few differences between them. One in particular is the safety record of both types - transport-category airplanes with envelope protection have a better safety record, one which continues to improve with time. What should go hand-in-hand with those "protections" is an understanding of what they do, what they don't do, and what happens when they fail. Both of your examples are very good examples of lack of the first two, and one is a classic example of the final one as well. There are also plenty of examples of breakdown in airmanship in non-'automated' airplanes on a pretty much daily basis. The issue is not "automation" it's the infrastructure and operators that put it into practice.

There is a class of aviator who flies a highly augmented FBW airplane to and beyond the extremes of a large flight envelope and deals with failures on a somewhat regular basis with (apparently) better success. They are, by and large, far better trained than your example and are part of a rigorous and continuous training and selection process. Where's 35AoA?

Nauga,
on both sides of the equation

 

[Greg Bockelman]

Perhaps you should ask a couple pilots who arrived just a little short at SFO? Perhaps you should ask three pilots who precipitated an Airbus in the middle of the Atlantic? Oh, that's right, you can't ask them 'cause they are dead.

Perhaps you should ask yourself why you are being deliberately obtuse?

None of that had anything to do with fly by wire.

 

[nauga]

None of that had anything to do with fly by wire.

Maybe it's also worth noting that FBW is not the same thing as automation. There are plenty of GA piston singles with lots of automation; however, there are none that are FBW (so far). There are also (or have been) airplanes with certain channels and/or axes that are FWB with little to no automation on those channels - just stick-to-surface electronically rather than hydro-mechanically.

I'm somewhat familiar with at least one example where a pilot thought he could outsmart the augmentation and gain a maneuvering advantage by turning off certain self-protection aspects. The publicly available details confirm that he broke his neck when he departed the airplane while looking over his shoulder and flew into the ground.

"Golden arms" are rare, and even rarer is the one who can fly better than the computer in an airplane that's designed around that computer.

Nauga,
from the right half-plane