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Questions tagged [fly-by-wire]

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

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1answer
129 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 ...
2
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1answer
137 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
345 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
201 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
371 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
219 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
120 views

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
72 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
661 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 ...
5
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1answer
333 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
95 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
487 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
478 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
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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
549 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
272 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
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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 ...
6
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1answer
447 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, ...
3
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1answer
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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
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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 ...
6
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1answer
706 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
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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
869 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
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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
820 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
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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
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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
425 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
271 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
927 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
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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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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
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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
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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 ...
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1answer
1k views

Does the 787 gust alleviation system make a more comfortable ride or for a more stable aircraft?

The 787 active gust alleviation system, similar to the system used on the B-2 bomber, improves ride quality during turbulence. Ride quality in a B2 bomber means a more stable weapons platform. Ride ...
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1answer
5k views

How does auto-trim work on fly-by-wire aircraft?

As I understand, you trim to reduce the effort needed to maintain the stick in the right position. Thus, you may reach steady flight before moving the trimming wheel. In fly-by-wire aircraft (to fix ...
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3answers
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Are NATO fly-by-wire fighters designed to feel like F-14 Tomcats?

Related question: Do fly-by-wire flight controls in airliners provide artificial feel? Icefire, by Judith and Garfield Reeves-Stevens, contains the following passage: When the engineers develop a ...
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1answer
8k views

How does the Airbus flight computer's voting system work?

From what I've read about Airbus planes is that their fly-by-wire system works by having three different flight control computers calculate what the plane should be doing and then vote on all the ...
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5answers
3k views

Can light GA aircraft implement fly-by-wire technology?

Theoretically, I know it is possible. I know the benefits of fly-by-wire too. My question(s) most revolve around: why it hasn't been done? What challenges1 would there be? What benefits are there by ...
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3answers
2k views

Could fly-by-wire protect against a takeoff tail strike?

If the takeoff weight is underestimated, rotation will be done too early and may result in a case of tail strike. One example of such mistake is a 747-400 (F-HLOV) in 2006 (case 8 in this study). The ...
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3answers
6k views

What would happen to the rudder on an A320 if both FAC systems failed?

What would happen to the rudder of an A320 if both Flight Augmentation Computer (FAC) systems completely failed during mid-flight? Would the auto pilot immediately pass control back to the pilots or ...