Questions tagged [fly-by-wire]

A technology which moves control surfaces by processing pilot input via software.

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2answers
155 views

On Airbus aircraft, can the pilot control the aircraft when the autopilot is active?

I am looking at the schematics of computerized control for Aibus aircraft and I do not understand the relation between the various control law and the autopilot. Under "normal law" can the pilot ...
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1answer
370 views

Does the pilot still have final control authority on modern Boeing airplanes?

In this answer it is said that Boeing (contrary to Airbus) gives final authority to pilots, but the example is about a 747-100(SP). This answer states, that modern Boeings have have a lot of fly-by-...
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1answer
310 views

How does the F-16 side stick convert pilot input to an electrical signal?

In What is the motivation behind designing a control stick that does not move? the F-16's control stick is discussed. What is the method that is used to sense the pilot's input to the stick and ...
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6answers
3k views

What is the maximal acceptable delay between pilot's input and flight control surface actuation?

While I was watching a cockpit video of an A330 landing in which the pilot was frenetically moving its sidestick, I wander what was the reaction time of this flight by wire system. Indeed, the time ...
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2answers
250 views

Could modern unmodified Airbus aircraft be used for zero-G flight?

ESA operates a mostly-stock A310 for their zero-G science flights, which doesn't have the flight envelope protection of more modern planes. Even then, a third pilot is required to monitor warnings to ...
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3answers
257 views

Does fly-by-wire permit smaller tail fins (area and thickness) for jetliners?

To prevent an XY problem, here's the context: A striking feature of the 777 is how small and thin its tail fin is compared to the 747. When I asked about this many, many years ago, someone told me ...
6
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1answer
487 views

How can the F-16 remain stable when there is a loss of hydraulic power?

Edit for justification: This question is different from If the EPU (Emergency Power Unit) on a modern fighter jet fails, will the aircraft drop out of the sky? for the following reasons: The ...
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1answer
152 views

What is the input range of common fly-by-wire controls?

What's the range that typical fly-by-wire controls (let's take A320 and B777 as examples) allow inputs in? The A320 controls in the y-axis of the side stick (forward/backward axis) the g load - what'...
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1answer
391 views

What is the Space Shuttle's command law?

The Space Shuttle was fly-by-wire. In today's fly-by-wire systems, the command law commands either the load factor and the roll rate (e.g., A320's normal law), or the surface control deflection (e.g., ...
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1answer
250 views

On an A320, will the aircraft compensate for constant pilot rudder input?

As I understand from answers to the question What does rudder input control in normal law in an A320?: the rudder deflection is the result of the sum of pedals input and plane's FBW command in normal ...
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1answer
608 views

What is the trim wheel behavior on the A320 family?

The Trim Wheel in the A320s usually is moving by itself, representing the current stabilizer position (or rather command). Before takeoff I believe it is set by hand to set the takeoff trim. During ...
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2answers
261 views

Do fly-by-wire fighter aircraft automatically reverse the direction of control surface deflections during a tailslide?

During a tailslide (a flight regime where the relative airflow over the aircraft is from the tail towards the nose; i.e., an attack angle between 90º and 270º; i.e., the airplane is moving tail-first),...
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0answers
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Are there attempts at fly-by-wire servo flap controlled rotor?

Reading this question and then this document about servo flap controlled rotor I was wondering if there has been any attempt at building one fixed hub helicopter with twistable blades hosting at 75% ...
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1answer
95 views

Does the HAL LCH have fly-by-wire?

Is Automatic Flight Control System (AFCS) the same as Fly-by-wire? If not what's the difference? India’s Hindustan Aeronautics Limited (HAL) has carried out the first flight of a Light Combat ...
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1answer
856 views

In an Airbus A320, when alpha protection is active, is pitch protection no longer available?

The A320 FCOM chapter 27 flight controls, normal law, protections, shows a diagram how the sidestick input is used when protections are active. When high angle of attack protection is active the side ...
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1answer
455 views

What sort of control mechanisms (i.e., PID controllers) do modern FBW aircraft use?

It's a well-established fact that aircraft like the Boeing 777, and all Airbus passenger aircraft that were designed after the A300, feature a digital fly-by-wire control system. Considering the ...
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1answer
112 views

Does the FBW system of a passenger aircraft use differential thrust for yawing? [duplicate]

Are there situations where the fly-by-wire system of a commercial passenger aircraft will use differential thrust to yaw? Or is that even possible at all (i.e. do the necessary interfaces exist)? I ...
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1answer
591 views

Fly-by-wire vs hydraulic systems [closed]

So, the great old argument, flyer-by-wire systems vs conventional hydraulics. I was wondering which one was better and why. Which one is safer? Pros and cons in terms of safety? Basically, I just ...
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2answers
518 views

Were Airbus planes always fly-by-wire?

So, as most of you know, Airbus has adopted fly-by-wire (fbw) technology. Pretty much every single plane made by Airbus is a fbw plane. So I was wondering, before computers were everywhere, did Airbus ...
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2answers
3k views

How does the Boeing 777's yoke of both the captain and the first officer have synchronized movement?

On Airbus planes, the side stick of both the captain and co-pilot are not synchronized in movement, meaning if you the captain moves the side stick, the co-pilot's side stick will not move together. ...
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2answers
628 views

Why did this A320 stall protection demo not hold Valpha max?

This video is about the Airbus A320 High angle of attack protection At 4:54 - 5:13 why did it pitch down? I know it is trying to maintain Valpha max but if it would ...
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1answer
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Why don't the A380 and A350 have trim wheels?

(wikimedia.org) A350 thrust levers without the flanking trim wheels. Why don't the Airbus A380 and A350 have trim wheels? On the other fly-by-wire Airbus aircraft the trim wheels are there for ...
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1answer
292 views

Could simple fly-by-wire controls be installed in a prototype as quickly as a mechanical system with an autopilot?

It seems that fly-by-wire systems can take longer to get certified as the testing requirements are much more extensive. A prototype aircraft wouldn't have to pass these tests. How much more time or ...
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6answers
8k views

Why can't the A320's computer-imposed limits be overridden?

Under the investigation section of US Airways Flight 1549, it is noted that [The pilot] asserted that insufficient credit was given to the A320's fly-by-wire design, by which the pilot uses a side-...
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6answers
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Why did fly-by-wire systems take so long to implement?

The first commercial FBW airplane was the Airbus A320, which was introduced in the late 1980s. This system only worked after decades of research by American and European aerospace companies. If FBW ...
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2answers
590 views

Can the fly-by-wire system of a modern airliner handle an unstable condition?

According to this answer airliners/large passenger aircraft such as an A320 are designed such that they are longitudinally, statically stable under normal flying conditions. What if, for some reason, ...
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1answer
3k views

What are the main components of the Airbus fly-by-wire system? Is ECAM related to FBW?

I'm assuming that all commercial Airbus planes use a similar, if not identical, system. Can someone give me an overview of the parts of the Airbus fly-by-wire system? I've also heard of ECAM. Is ECAM ...
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3answers
4k views

What kind of delay does the A320's fly-by-wire system add?

More precisely, I am wondering if there is any kind of data on how long it takes between moving the sidestick and observing a reaction on the ailerons or elevator. I know that the physical control ...
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1answer
810 views

Are there any fly-by-wire airliners with negative or near-neutral pitch stability?

Are any modern commercial airliners with fly-by-wire flight control systems designed with negative or near-neutral pitch stability so that they can take advantage of the capability of such systems to ...
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3answers
1k views

How much computing power is needed to keep commercial and military planes flying?

I've always wondered, what sort of computing power is needed to keep modern commercial and military planes in the air? There are many systems of a modern commercial plane (e.g an Airbus A350), that ...
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8answers
5k views

Would a wireless fly by wire system be practical?

Given that most modern aircraft are controlled using the fly by wire system, what is the likelihood or the drawbacks of transmitting those fly by wire instructions from the cockpit and or cockpit ...
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1answer
996 views

What kind of cable is used to transmit signal from flight control computers to actuators?

I am a student and have been researching about ARINC 629 and AFDX. In b777 fly-by-wire system, what kind of cable is used to transmit analog signal from Actuator Control Electronic (ACE) to the ...
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1answer
6k views

Why is it not recommended to hold the nose up on the A320 after touchdown?

I was recently told by a trainer in my airline that on the A320 if we hold the nose up after main gear touchdown then the flight control laws logic will memorise that pitch attitude after 5 seconds ...
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1answer
3k views

Why do flaperons 'move down then up' on takeoff roll on a 787?

The flaperons on the 787 go through certain motions once the TO/GA is pressed. I've always seen it when the 787 is viewed from behind on takeoff. The motions are completely symmetrical, i.e., not ...
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2answers
4k views

What does stick fixed and stick free longitudinal stability mean in simple terms?

What is the significance of stick fixed and stick free terms in aircrafts with mechanical control and modern fly-by-wire control?
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2answers
2k views

What exactly happened with the Flight Computers on XL Airways Germany Flight 888T?

I recently saw a documentation about XL Airways Germany Flight 888T. This made some questions rising in my mind: Two AOA-Sensors failed (freezed) simultaneously. From Wikipedia: Two out of three ...
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2answers
833 views

Can flight control computers detect and help to avoid pilot-induced oscillations?

With flight control technology available today like fly-by-wire, digitally augmented command inputs etc., I wonder whether any technical solution exists (or could possibly exist) to detect and counter ...
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2answers
2k views

Is A380's center of gravity really too far back?

I have searched and even studied plans from Airbus itself, but I was not able to confirm the following and would like to ask if the information I have is correct. TLDR version so you don't have to ...
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3answers
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How do pilots adjust trim on the B777, where the control forces are simulated?

I know that pilots of small airplanes (e.g. Cessna 172) use force to trim, i.e. they hold the required attitude using the yoke, then trim the aircraft until no force is required to hold the yoke in ...
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2answers
1k views

How are Airbus pilots trained for using the mechanical backup control systems?

The A320 and friends have mechanical-only control capability (manual pitch trim + rudder pedals) for cases of total fly-by-wire computer or electrical failure. Obviously, this would be covered in ...
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2answers
4k views

Which CPUs and programming languages are used in new airliner flight control systems?

Are the new systems of today built with the same CPUs and programming languages and development software as those of 20 or more years ago? By new I mean that these systems are currently being ...
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1answer
453 views

How does a flight control computer deal with control surface disengagement?

What action does the flight control computer take (under normal law) when it realizes, for instance, Inboard actuator of aileron/elevator disengaged or There is a disconnect between the LVDT and ...
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0answers
286 views

Are direct law command gains monitored for correctness when flight control computer is in normal mode?

This question is specific to Bombardier C-Series aircraft which has three modes: Flight control computer normal mode, FCC Direct mode and REU direct mode: (I am not sure if other aircraft have an ...
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1answer
1k views

How does pilot know when to trim when flying an aircraft that have fly by wire flight control computer [duplicate]

My understanding of trim (on non fly by wire aircrafts) is that when the pilot feels force on his column or side stick, he trims the aircraft (either up/down) until the forces on the stick or yoke are ...
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2answers
1k views

How is a fly-by-wire system realized in big planes?

For example if whole system is build on CAN protocol that give maximum rate of 9000 messages per second with IMHO is quite low number for big plane. Can you give me any example how this problem was ...
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2answers
3k views

Do Airbus pilots have to practice flying in alternate law?

I'm sure when getting their type rating for Airbus FBW aircraft pilots learn how to fly in alternate and direct law. After that how much opportunity do they get to practice this skill? On Air ...
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6answers
4k views

Why aren't there simplified fly-by-wire helicopter controls?

I was discussing helicopter control with relatives over the holidays, particularly regarding how difficult it is to fly one and how changing any control requires adjusting the other two main controls. ...
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1answer
3k views

What are the “channels” on the A320 Rudder Travel Limit Unit?

The KNKT's final report on last year's Air Indonesia QZ-8501 crash repeatedly mentions that the faulty solder joint on the Flight Augmentation Computer (FAC) caused an open circuit on "both channel A ...
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4answers
15k views

What is fly-by-wire?

What exactly does the term "fly-by-wire" mean? Where did it originate? I understand that it refers to control systems. If an aircraft is not fly-by-wire, what is it? That is, what are the alternatives?...
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2answers
9k views

How are fly-by-wire airliners controlled in case of complete electrical failure?

In this comment, it is postulated that even fly-by-wire aircraft (Airbus) are demonstrated to fly without any electrical systems. All Airbus aircraft are demonstrated controllable with complete ...