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Questions tagged [control-surfaces]

Use for control surfaces; for the cockpit controls, use [flight-controls] instead.

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17 votes
0 answers
1k views

What causes the "dead band" phenomenon during takeoff on the Boeing 737?

During takeoff, the Boeing 737 encounters a distinctive "dead band" phenomenon after the initial pitch reaches approximately 10 degrees. Essentially, a slight increase in back pressure is ...
9 votes
4 answers
3k views

Under what circumstances does the F-16 and possibly similar fighters deploy leading edge slats?

What does the F-16 (perhaps other fighters as well) use to decide when to deploy leading edge flaps? I would assume angle of attack, airspeed, stick deflection, or some combination of the three, are ...
11 votes
3 answers
1k views

Do aircraft using only spoilerons for roll control, with no conventional ailerons, have a crossover airspeed?

Airplanes generally have a crossover airspeed (a minimum airspeed below which directional control of the airplane cannot be maintained in the event of a rudder hardover). This is because, as airspeed ...
0 votes
1 answer
71 views

Can a single-bladed rotor with cyclically varying torque emulate a swashplate?

Instead of a swash-plate cyclically varying the pitch of the rotor blade(s), could a similar effect be generated by cyclically varying the thrust of the motor on a fixed-pitch single-blade rotor? The ...
2 votes
1 answer
209 views

How to develop motion model for RC plane

I'm interested in controlling an RC plane autonomously, and to do that I need a basic motion model. How would I do this? Particularly without a wind tunnel?
4 votes
2 answers
305 views

Are control surfaces less effective at supersonic speeds?

I am unsure if this is correct but this is my current explanation: Once past supersonic speeds, the larger the speed the larger the divot of air pressure around the plane. Because these divots can get ...
12 votes
5 answers
4k views

Why isn't the rudder below the tail?

Most airplanes have a rudder on top of the tail. When it is turned to the left, it causes the plane to yaw to the left. But it also puts a roll force to the right, because it is usually above the ...
1 vote
1 answer
458 views

How are flaps and the elevator positioned in cruise?

so I understand that an elevator is used to maintain cruise (straight level and unaccelerated flight) but I’m curious now about how the flaps and elevator is positioned whilst an aeroplane is trying ...
6 votes
2 answers
943 views

How do you know the maximum load a control surface can withstand?

source This is a separate strength testing (load testing) of the elevator of an airplane, how was the load determined? How did the engineers determine the maximum elevator load?
2 votes
0 answers
181 views

Boeing 777 PCU Synchronization of Duplicate Hydraulic Actuators for Control Surface Deflection

I have a question regarding the redundancy of hydraulic systems used to deflect the control surfaces of a Boeing 777 aircraft (or the like). We know that "the elevators, ailerons, and flaperons ...
5 votes
1 answer
396 views

How do rolling airframe missiles steer?

There are a certain type of missiles that roll constantly in flight, so-called rolling airframe missiles. Missiles found in the category range from various MANPADs, to the creatively named RIM-116 ...
4 votes
2 answers
2k views

Why does the trailing edge have a more pronounced taper than the leading edge on the Cessna 172?

Why does the Cessna 172 have a more pronounced taper on the trailing edge as opposed to the leading edge?
13 votes
8 answers
8k views

Can all airliners be turned without rudder input?

Is it possible for pilots to make a right or left turn, using just the ailerons and without rudder input in all airliners? If not why so, for what reason?
4 votes
2 answers
1k views

In F-16 the pilot or the FLCS , deflect the rudder to correct the adverse yaw effects in direction of roll during an aileron roll or in opposite way?

Is the rudder moving by FBW in direction of roll or in the opposite direction? I understand that the rudder is used due to the ARI system (ailerons - rudder interconnect), but don't have any idea ...
14 votes
5 answers
6k views

Do fighter jets use elevators as ailerons?

I saw jets in game using elevators to roll right and left, but I never saw them doing in real life. I was wondering if fighter jets actually use elevator to roll like they do in game.
4 votes
1 answer
154 views

Are flaps regulated as balanced control surfaces?

I was talking about flutter the other day and how it occurs with the ailerons able to flap out of sync with the wing. I realized that the flaps, could in theory, move in a similar way. However, the ...
0 votes
1 answer
87 views

How do hybrid control surfaces work?

I am trying to build a self-stabilized model rocket with actuated fins. Suppose the rocket has 4 fins. The diagonal fins must rotate together to control the yaw/pitch motion, and all the fins are ...
9 votes
3 answers
4k views

Why is the tail group of virtually every airplane swept instead of straight?

Even low performance airplanes like ultralights have their tail group (vertical and horizontal stabilizer with rudder and elevator) swept backwards knowing fully well that a straight tail group will ...
1 vote
1 answer
144 views

Control surfaces on radio-control models of airliners

Do large RC airliners like the huge Emirates RC A380 still need all the same control surfaces that a real A380 has I,e leading edge slats? If not why is this the case. Many thanks for your time in ...
23 votes
4 answers
4k views

Why were the Space Shuttle's elevons reversed, early in re-entry?

The veteran Space Shuttle commander Charlie Precourt writes, in the July 2022 issue of EAA's Sport Aviation, p. 38: Another interesting reality about our flight controls was their working essentially ...
14 votes
2 answers
4k views

Why are the grid fins on Starship pointy and sharp?

The grid fins on Starship are serrated, why? Does it help in transonic maneuvers? Source: Starbase Factory Tour with Elon Musk [Part 1], YouTube, at 30:28
3 votes
2 answers
682 views

Are spoilers primary or secondary flight control surfaces?

The literature on primary and secondary flight controls is very contradictory. My professor provided this image from which I infer that spoilers are used for primary flight control: Also, here it ...
5 votes
3 answers
1k views

Could a trim system conceivably manipulate only primary surfaces?

Most airplanes' trim systems manipulate a tab associated with a primary surface. For example, a pitch trim tab (secondary surface) is attached to the elevators (primary surface) and will change the ...
-8 votes
2 answers
186 views

What about measuring airspeed from control surface forces on the framework?

I watch a lot of these videos that people make about air disasters. One factor that seems (or hopefully seemed) to crop up is where pilots get hopelessly confused about airspeed, particularly (it ...
13 votes
3 answers
2k views

Why are the red/white control surfaces under the wing extended during a take off?

These pictures are more than a little dated as the CF-101 Voodoo's have not been flown since the mid 80's. In these two photos we can see the Voodoo is performing a full afterburner take off. Note ...
8 votes
1 answer
4k views

Why does the Eurofighter Typhoon have a long arm canard versus the close coupled canard of the Dassault's Rafale or the JAS-39 Gripen?

The Rafale and the Gripen are quite similar but the Eurofighter Typhoon has the canards far forward. I've been told that this was due to the shape of the air intake. Apparently the Typhoon's air ...
8 votes
1 answer
2k views

How do canard flaps work?

Before examining this XB-70 picture Wikipedia XB-70 photo I thought that all canard were one single flight control surface (as seen on many fighters such as the Eurofighter Typhoon), and that there ...
11 votes
3 answers
3k views

Why do the ailerons of this flying wing work oppositely compared to those of an airplane?

I made this simple wing glider and put some ailerons on it. I thought that the ailerons in this glider would work the same way it works on airplanes, wherein the roll will be in the direction of the ...
-2 votes
2 answers
196 views

How does control system design ensure correct elevator position with the steering system unlocked? [closed]

I’m having some trouble answering the following problem encountered in one of the worksheets for aviation students: The plane shown in the picture stands on the runway. The pilot, while getting off, ...
0 votes
0 answers
119 views

what is considered a good pedal performance in a fighter?

What is considered a good performance in designing the directional control law in a fighter? Is it acceptable to have some roll when using a pedal? For example, is it acceptable to have 40 degrees ...
2 votes
1 answer
169 views

Does the pilot always need to use stick to compensate roll caused by pedal?

When the pilot uses pedal in a fighter like F-18, does the aircraft roll? If so, is it the pilot's job to compensate this roll or the control system compensates it automatically? In other words, is it ...
0 votes
1 answer
187 views

Control surface deflection during takeoff

What is a reasonable (or typical) control surface deflections required for takeoff? I would like to know two ball park values if possible elevator deflection for conventional transport aircraft ...
6 votes
2 answers
2k views

Why are there no high wing Canard airplanes?

Just had a thought about canard airplanes while looking at the Tu-144 that features a canard surface on the top of its fuselage. Are there any high-wing aircraft with a top or bottom mounted canard? ...
13 votes
1 answer
1k views

How are control surface problems in wings having high bending dealt with?

In some aircraft which have large wing deflection due to bending, do ailerons or flaps not get stuck or bent themselves? In the case where hinging axis is also bent how do ailerons operate?
16 votes
1 answer
3k views

What is the purpose of this aileron trailing edge strip?

See the following photos of the LH aileron of a Beechcraft King Air B200: Source: own work Source: own work As seen in the above photos, the Beechcraft King Air B200 has what I would describe as a ...
10 votes
2 answers
2k views

How exactly do the Beechcraft 1900's stabilons work?

The Beechcraft 1900, in addition to the usual wings and vertical and horizontal stabilizers, and the extra vertical tail surfaces added for improved directional stability, has a pair of horizontal ...
3 votes
1 answer
145 views

Angle of Attack influence on Adverse Yaw

we are analyzing an aircraft's lateral-directional control characteristics with self-made code. We have observed that the aileron's influence on the body axis yaw moment is quite sensitive to the ...
4 votes
2 answers
3k views

How strong would a servo motor need to be to power the control surfaces of a fixed wing ultralight aircraft?

I'm looking to build an ultralight aircraft. The video above shows a good example of how one is controlled with wires or with metal fulcrums/levers, but I am ...
4 votes
1 answer
383 views

What is the maximum control surfaces deflection on a Cessna 210N?

Does someone know how far the control surfaces (rudder, ailerons, elevator and nose gear) can deflect in a Cessna 210N? I've been searching Google and the POH for hours now and can't find it.
2 votes
1 answer
643 views

Why would control-surface balance horns cause problems at transonic speeds?

On many aircraft, control surfaces such as elevators, ailerons, rudders, etc., have "horns" which extend forwards of the surface's hingeline, wrapping around the tip of the wing or ...
6 votes
2 answers
2k views

What is the benefit of a horn control surface?

Like the one above. Is it just so that you can hinge closer to the leading edge of the aileron or control surface? Why did the designers of the ATR-72 elect to use this feature?
2 votes
1 answer
1k views

Do the different spoilers on an A321 extend by different amounts? [duplicate]

I recently flew with an A321 and watched the left wing while the pilot tested the control surfaces before lift off. I noticed that one of the spoilers angled upwards much less than all others. In the ...
1 vote
1 answer
190 views

What are the degree markers on the tail of this MD-10 for? [duplicate]

I took this picture of of Orbis's McDonnell Douglas MD-10-30. Tail: N330AU. What purpose do the 0 and 2 degree markers serve?
1 vote
3 answers
218 views

Replacing cyclical control with tilt-able rotor using EV motors and servos

I understand the traditional reasons for cyclical control (with swash plates) on helicopters; ie, avoid gyro effect, shaft can be fixed. However, if the power plant was a modern EV motor, and ...
1 vote
3 answers
1k views

What are some common aileron failures?

There are a few parts to the control system for an aileron in a light aircraft, such as the rods, bellcrank, cables, chains etc. What are the main reasons for aileron failures and what parts wear the ...
-1 votes
3 answers
276 views

What should a pilot do if none of the control surfaces are responding? [closed]

What would a pilot do if none of the control surfaces are responding? For example, a pilot flies a medium-sized plane and to make the situation a bit less hectic, they're the only one onboard. Then ...
9 votes
6 answers
2k views

Can flaps be used to perform rotation and flare?

TL; DR using flaps to directly control sink/climb rate near ground = simpler and faster response = easy to fly airplane? Rotating is the pitch up during takeoff that causes the aircraft to leave the ...
0 votes
2 answers
175 views

What suits best for lateral controllability at high Angle of Attacks- a vortex generator or wing slots?

At high angle of attacks, the prominent problem is the separation of airflow. And if this airflow separation is near ailerons, we lose lateral controllability. And the solution is making the flow ...
10 votes
1 answer
1k views

Why do some Mach trimmers move the elevator?

A pop-up rod on a the FO's control column on a DC-9 that shows the Mach trim position. (YouTube) Regarding the title, I'm not sure if it's just some or all jetliners (I tried to research it). On the ...
3 votes
1 answer
783 views

Why does the Cessna 208 Amphibian have extra tail surfaces?

Mark Harkin, CC BY 2.0, via Wikimedia Commons I've seen extra tail surfaces that look like additional vertical stabilizers on the C208 Amphibian. Why is there a need for this? I can't imagine that ...