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Questions tagged [flight-controls]

The methods or mechanisms used to control an aircraft's movement in roll, pitch, and yaw.

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0answers
24 views

What's is the range for common fly-by-wire controls to allow control inputs in?

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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2answers
55 views

What is the THS deflection speed?

Let's restrict this question to best sellers airliners (A320 and B737). On this aircrafts, the THS is used for pitch trim. The speed requirements may not be has intense as for elevator as it control ...
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6answers
2k views

Why not use the yoke to control yaw, as well as pitch and roll?

(Inspired by this question about rudder hand control on joystick-equipped aircraft.) Most civilian fixed-wing aircraft (post-1987 Airbus airliners being the primary exceptions) use a yoke (...
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1answer
303 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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0answers
65 views

Change in target coordinates effect on bomb energy [closed]

Given a bomb that is guided towards a target that is X NM downrange. The bomb does not have a motor. My question is the following. What directional change in the target location will cause the bomb to ...
10
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1answer
1k views

Why did AF447 never return to normal law?

Air France Flight 447 degraded from normal law to alternate-2B law when its pitot tubes were temporarily filled with ice crystals, resulting in a loss of airspeed data. As a consequence of being in ...
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0answers
26 views

What is the importance of Lyapunov stability for non linear control? [migrated]

I understand that studying stability gives a particular region from which if we start it will converge to an equilibrium point. But why is the study important specifically for designing non linear ...
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2answers
101 views

Does load factor affect roll rate?

To be clear I am referring to a given aircraft at a given weight, speed, attitude, etc everything else the same except one is at say 0.5g and the other at 2.5g will there be a difference in roll rate ...
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0answers
59 views

Do aircraft use some kind of stability control to keep the aircraft on the runway during landing? [duplicate]

Modern automobiles use an electronic system called ESP to keep the car on track in slippery situations. Do modern jet liners have a similar system to aid the pilot in keeping the aircraft on the ...
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0answers
60 views

Would throttle steering of a forward-swept-winged aircraft be possible?

Fortunately (or perhaps unfortunately, given the number of crashes that had to occur for us to figure it out), the use of throttle manipulation to control an airliner with disabled primary flight ...
3
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2answers
207 views

Why would Boeing's MCAS be preferable to a modified Feel and Centering Unit?

According to some sources, the purpose of MCAS on Boeing's 737 MAX variants is to increase the back-force needed to further raise the nose when flying manually at high angles of attack, in order to ...
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1answer
217 views

Why can't the 737 MAX's horizontal stabilizer autotrim be cut out by control yoke inputs?

According to this article, a horizontal stabilizer runaway on the 737 MAX, unlike with all other 737s, cannot be countered with yoke inputs: Older 737s had another way of addressing certain ...
8
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1answer
484 views

Why does the flight controls check come before arming the autobrake on the A320?

As per SOP on the A320 we first perform the flight controls check and then arm the autobrake to max. What is the reason behind this?
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1answer
160 views

How do you disable plane AI when the plane goes crazy? [duplicate]

This came to my mind when I learned 737 MAX crash was caused by the AOA indicators giving faulty info to the AI which crashed the plane. So how do you completely disable the flight computer when it ...
4
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2answers
228 views

What does rudder input control in normal law in an A320?

I understand form documentation that in normal law, pedal input is not necessary to keep coordinated flight. It is merely said that using the pedals is not necessary. Later in the documentation it is ...
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0answers
64 views

How are these flywheel-like devices used in the Boeing 737 Max? [duplicate]

The recent news video CNN's exclusive look inside a Boeing 737 Max simulator shows a 737 Max simulator cockpit. There are a pair of what look like large black flywheels on the console, shown spinning ...
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2answers
498 views

Has the Boeing 737 MAX MCAS system successfully prevented a stall or approach to stall condition outside testing?

The Boeing 737 MAX MCAS system has been in the press a lot as it has been implicated as a possible cause of 2 fatal crashes. The MCAS system was put in to prevent a wing stall caused by excessive ...
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2answers
207 views

Why do the stabiliser trim wheels not move exactly in sync?

I've watched a few videos about the Boeing 737, and in particular because it's a bit of a current topic, about the stabiliser wheels in the cockpit. On some of these videos, which are often in ...
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2answers
158 views

Why does a pilot bank up to 5 degrees into the operating engine following failure of the other engine?

For Vmc condition, one of the solutions is to bank up to 5 degrees into the operating engine to increase rudder effectiveness to maintain control. Why is it up to 5 degrees? What happens if the pilot ...
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0answers
396 views

How does the 737 MAX MCAS differ from stab trim in other 737 variants? [closed]

I have the following questions: MCAS will not cut out from excessive control column movement as non-MAX 737 aircraft stab trim does. Is that correct, and is this cutout permanent or does it re-...
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1answer
103 views

How does a circulation control helicopter work

This essay describes that this helicopter uses circulation control of the rotor for cyclic and collective control, but not how circulation control works. https://ntrs.nasa.gov/archive/nasa/casi.ntrs....
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2answers
99 views

What does 'in-trim speed' mean with respect to Boeing 737 mis-trimming correction?

This question was prompted by discussions of the recent Boeing 737 MAX crashes, but it is not specifically about that variant. In Boeing's 737 NG Flight Crew Training Manual, in Chapter 8 (Non-Normal ...
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1answer
179 views

Why does the A320 use the rudder for lateral control in mechanical law?

When the Airbus A320’s flight control system is operating in mechanical law (the simplest and lowest-tech of the A320’s flight control laws, where deflections of the pilots’ joysticks are transmitted ...
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1answer
150 views

Why don’t airliners use stabilizer movement to assist with large pitch control inputs?

Most large airliners not only have elevators for pitch control, but also moveable horizontal stabilizers. The elevators are used for primary pitch control, with the stabilizers being used to trim the ...
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2answers
396 views

On a modern Aircraft like the A320 or B737, is it possible to disable computer interference with the control inputs of the pilots?

One more question due to the recent and unfortunate events in the case of the second ever B737 Max 8 crash. As far as I know, the first of the two crashes was caused by the MCAS System, that ...
5
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4answers
198 views

Why does elevator still raise and lower the nose when the aircraft is steeply banked?

In a steep turn, the aircraft is basically sideways. However, when executing a steep turn, one still raises and lowers the nose of the aircraft by using the elevator. Intuitively, it seems to be ...
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5answers
2k views

What is the difference between a forward slip and a side slip?

I am having a hard time understanding what differentiates the two types of slip. I understand that in a forward slip, the longitudinal axis is tilted with respect to the flight path, whereas in a side ...
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1answer
156 views

Why does the DHC-6 have only one set of elevator cables?

Air Moorea Flight 1121 crashed because its up-elevator cable broke, allowing the elevator to blow to its faired position and thus be unavailable to counteract the pitch-down moment caused by the flaps ...
4
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1answer
158 views

Why does the A320’s maximum allowable aileron deflection decrease, rather than increase, when the flaps are extended?

According to this answer to why the A320 uses mainly spoilerons for roll control during landing, rather than conventional ailerons, the ailerons can’t extend as far when the flaps are extended, for ...
6
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3answers
424 views

Are there left seat qualifications specific to actual handling of the aircraft?

The following three posts explain that both yokes and side-sticks require changing the hand that holds the yoke/side-stick when switching seats: Why are Airbus captain control sticks placed on the ...
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1answer
213 views

Why were the space shuttle’s flight controls only certified for low airspeeds?

Somewhat ironically for a vehicle designed to reach orbital speed, the space shuttle’s flight control system was only certified for airspeeds up to 333 KIAS, and exceeding 470 KIAS (the maximum ...
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1answer
88 views

During multiengine training, are pilots taught how to use the throttles for control?

The use of a multiengine aircraft’s throttles for steering and pitch control is critically important should the aircraft’s primary flight controls fail or severely malfunction; are pilots nowadays ...
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2answers
110 views

What happens when you apply full cyclic + collective?

Can a helicopter apply full cyclic and then full collective at the same time? Would'nt the blades on one side (opposite of the intended tilt direction) have already maxed their aoa, resulting in a net ...
3
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1answer
128 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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2answers
316 views

Why was the 737 main rudder servo valve’s vulnerability to causing uncommanded reversals never discovered in testing?

As was discovered during the NTSB investigation into the crash of USAir Flight 427, the design of the servo valve inside the main rudder power control unit (PCU) formerly used on 737 Original- and ...
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1answer
38 views

Are there any special considerations involved in designing manual flight controls for supersonic/hypersonic aircraft?

What things, if any, might need to be taken into account in the design of manual flight controls for supersonic or hypersonic aircraft that wouldn’t need to be taken into account with manual controls ...
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1answer
152 views

Why didn’t the 757 have manual-reversion capability?

The Boeing 757 was the highest-capacity and latest-designed narrowbody Boeing ever produced (and, in the case of the 757-300, the highest-capacity narrowbody anyone ever produced); it was also the ...
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0answers
30 views

Effect of Rudder on Velocity Vector

Suppose we have an aircraft flying in steady, level flight at zero angle of attack. In this configuration, the velocity vector $\vec{V}$ is perfectly aligned with the $x$ axis. At some time $t=t_0$, ...
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0answers
50 views

Why is a stabilator more effective? [duplicate]

As far as I know, a stabilator is an elevator made up of the entire horizontal stabilizer. Why is it more effective?
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2answers
305 views

Why do aircraft have a crossover airspeed, and why does it increase at higher vertical load factors?

According to the NTSB accident report on the crash of USAir Flight 427, all commercial aircraft have a crossover speed (the speed at which the maximum rolling force from the aircraft’s ailerons and ...
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1answer
187 views

Why is the 737’s aileron/spoiler authority reduced at low flap settings?

According to the NTSB report on the crash of United Airlines Flight 585, the ability of the 737’s lateral controls (ailerons and flight spoilers) to counteract the rolling forces produced by (say) a ...
3
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1answer
180 views

Why are the Convair 880's yokes shaped differently from each other?

Looking at this picture of a Convair 880's flight deck... (Image originally by the San Diego Air & Space Museum at Flickr, via Wikimedia Commons) ...the captain's and first officer's control ...
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2answers
153 views

Can horizontal stabilizer trim be worked independently (each side)?

I notice most jetliners have a big trim wheel on each side of the center console. This wheel is black with white stripes, and notably turns on its own via the autopilot. Two large trim wheels: And ...
4
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1answer
107 views

Can roll be controlled through elevators in a fixed-wing aircraft? [duplicate]

In fixed-wing aircraft, roll is typically controlled through ailerons. But I am wondering if roll could also be controlled through split, independently controllable left/right elevators?
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0answers
79 views

Is there any book like the “Stick and Rudder” about the helicopter?

I have read the Stick and Rudder, that's really a classic book. Now I want to study the flight theory about helicopters, is there any book like this?
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1answer
4k views

Why doesn't a full yoke deflection also change the stabilizer trim on the Boeing 737 MAX?

Various websites have stated that during the 737-MAX crash in Indonesia, the pilots could not pitch up because of a faulty AOA sensor pitching the plane down. The stabilizer has a rear fulcrum and ...
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2answers
285 views

When is aileron trim used?

There is an aileron trimmer in some Boeings. When and why should it be used? P.S. I'm not a pilot, can you answer with less smart words?
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1answer
3k views

Identification of this control panel for a four-engine plane

While cataloguing a printer's copper plates I came across a control panel image, and I have attached it here in the hope someone can identify what plane it's from. The Lorenz blind-landing instrument ...
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1answer
126 views

What is the meaning of 'stall' in this sentence? [duplicate]

I have no knowledge about aviation. Can somebody tell me what is the meaning of "he ran through a series of stalls" in: He ran through a series of stalls, killed the engine, and brought the plane ...
2
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1answer
256 views

Why didn’t the space shuttle have flight control manual-reversion capability?

The Wikipedia article on STS-1 (the first orbital space shuttle mission), in a discussion of all the problems and malfunctions occurring during the mission, mentions that, due to an unexpected ...