Questions tagged [flight-controls]

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

-1
votes
0answers
14 views

Plot response of a MIMO system with individual inputs in MATLAB using lsim, step or anything like that [on hold]

I need to plot response of a 2 input 2 output system with by controlling each individual input i.e For example, I want to give a reference input of 5 degree to Side slip angle and 10 degree to the ...
0
votes
0answers
18 views

How to calculate variation of Z force with elevator deflection (Zδe) in Nelson for pitching dynamics?

I have been trying to model the pitching dynamics of a General Aircraft (Nelson : Flight Stability and Control) but during the modelling, I find that I need to use the ...
6
votes
1answer
327 views

Did the Douglas SBD Dauntless have a second set of controls?

In the book Never Call me a Hero, the author mentions that there were controls in the rear seat of the Douglas SBD Dauntless. However, I don't recall ever hearing this before, though I know the TBD ...
16
votes
1answer
3k views

What happens to Cessna electric flaps that are moving when power is lost?

On final in a C182T you move the flap control arm from 20 to FULL, and when halfway there, the breaker pops (or BUS1 fails, a wire falls off, etc.) Does the flap stay where it is, slide back to 20°, ...
0
votes
2answers
228 views

B777- In emergency mechanical back up how does the flight controls manage engine failure

In case of engine failure above the ocean with multiple electrical failures and after having exhausted the batteries the fly by wire mechanical backup with available hydraulics if left with the THS ...
3
votes
2answers
156 views

Are modern commercial airliners flyable without operational computer systems?

Do modern commercial airliners have manual control capability to fly and land if electric power remains on but all computer systems and digital communication/guidance fails?
6
votes
3answers
4k views

How strong someone should be in order to fly without “power steering”?

Planes these days use fly by wire systems while older ones had a mix of hydraulics with electronic assistance like the MD-11 (And maybe 737-800?). But what would happen if you lost the electronic ...
2
votes
1answer
288 views

Why isn't a human required to confirm visually that flight controls are moving?

On this A380 flight after pushback and engine start and before taxi, Capt Juergen Raps and and Sr FO Harald Tschira rely solely on their FID to check flight controls. On a regular flight without ...
2
votes
0answers
47 views

What failure modes did Airbus seek to eliminate or mitigate when they changed the design of the A310/A300-600's rudder travel limiter?

In the NTSB report on the crash of American Airlines Flight 587, it is mentioned (in the context of the changes between the A300-B2/B4's rudder system, on the one hand, and the A310/A300-600's rudder ...
-2
votes
2answers
127 views

Would a long pole help stablize a jet pack?

Jet packs are classically worn like a book-bag on the back. Would it be more stable if the exhaust ports were separated? Would the jet pack be easier to control if the turbines were at the ends of a ...
2
votes
4answers
2k views

What could be the cause of an uncommanded roll at high speed?

I have a problem with a T-38. There is uncommanded roll to the left when the aircraft flies at 250 knots. But as the aircraft speed goes up around 500 knots, the uncommanded roll is now to the right. ...
1
vote
1answer
103 views

How will the alpha lock function intervene when performing a takeoff at heavy weights on the A320?

In the FCTM for the A320 family of aircraft's under the SOP Takeoff chapter it is mentioned that the alpha lock function can intervene when performing a takeoff at heavy weights. Can someone please ...
7
votes
1answer
149 views

Why is the speedbrakes rate of retraction 25 seconds when used at speeds greater than 315 knots/.75 Mach on the A320?

While I was routinely reading the FCOM normal procedures I came across a note with regard to the speedbrakes retraction time going up to 25 seconds when we use them at speeds at or over 315 knots / ....
2
votes
1answer
138 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'...
1
vote
2answers
101 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 ...
15
votes
6answers
3k 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 (...
12
votes
1answer
349 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., ...
11
votes
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 ...
4
votes
2answers
137 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 ...
1
vote
0answers
62 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 ...
1
vote
0answers
78 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 ...
9
votes
3answers
437 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 ...
4
votes
2answers
455 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
votes
1answer
576 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?
-4
votes
1answer
230 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 ...
5
votes
3answers
355 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 ...
3
votes
0answers
77 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 ...
5
votes
3answers
611 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 ...
5
votes
2answers
304 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 ...
2
votes
2answers
223 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 ...
2
votes
0answers
519 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-...
0
votes
1answer
107 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....
1
vote
2answers
206 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 ...
1
vote
1answer
286 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 ...
3
votes
3answers
218 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 ...
5
votes
2answers
437 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 ...
6
votes
4answers
214 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 ...
10
votes
5answers
3k 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 ...
0
votes
1answer
164 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
votes
1answer
234 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
votes
3answers
436 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 ...
1
vote
1answer
227 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 ...
2
votes
1answer
95 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 ...
2
votes
2answers
123 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 ...
6
votes
2answers
220 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),...
3
votes
2answers
387 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 ...
1
vote
1answer
41 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 ...
2
votes
1answer
188 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 ...
1
vote
0answers
33 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 $t=t_0$, ...
0
votes
0answers
51 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?