Questions tagged [control-surfaces]

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

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Are the functions of ailerons and rudder similar?

The ailerons help the plane to bank left/right by increasing lift to one wing and decreasing in another. Likewise, the rudder also helps in turning the plane by yawing and deflecting the nose right/...
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11 votes
1 answer
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What are the pros and cons of having canard control surfaces versus a horizontal tail control surface?

For a normal civil aviation aircraft, what are the pros and cons of having Canard control surfaces or horizontal tail control surface?
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19 votes
3 answers
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Why is the Tu-144 the only commercial airplane with canard configuration?

I understand the delta wing was chosen because of the supersonic cruise (like the Concorde), and canards were added to reduce the approach/landing speed. But canards may be used without delta wing (e....
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14 votes
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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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10 votes
2 answers
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How does trim work on an A320?

In the very interesting answer from Jan Hudec to a question about the various flight control computers on Airbus planes, two different means to trim the aircraft are mentioned: The stabiliser and the ...
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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.
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19 votes
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What is the purpose of these odd "control surfaces" on the BAE Taranis?

I was looking at a video of the BAE Taranis, and noticed these weird control surfaces: There is a matching pair on the underside. They don't seem to move at all throughout the video, even on landing, ...
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6 votes
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Is there a parameter that links the areas of the fuselage and control surfaces? [closed]

Do aircraft designers look at the ratio of how much fuselage surface area can be loaded onto a given unit of wing and tail surface area including elevator, aileron, rudder etc? (Possibly, the surfaces ...
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12 votes
2 answers
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How does flight control surface authority change with AOA?

I am working on semi-realistic (let's just call it "believable") flight simulation component set for a game engine. One of the topics that I tried to research but could not find reliable information ...
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8 votes
3 answers
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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 ...
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How is pitch controlled in a flying wing?

How do delta wing or flying wing aircraft maintain their pitch attitude in the absence of an elevator? I understand that the ailerons on the wings do control the banking/roll, but they are ...
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How are the dimensions of the empennage determined for jetliners?

How is the height of the vertical and span of the horizontal stabilizers determined for different turbofan aircraft like the Airbus A380 and the Boeing 747-8? What are the maximum forces (in ...
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2 votes
4 answers
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How can larger wingspan decrease the strength of wingtip vortices?

In the last paragraph from the link below, it states that Vortex Strength is inversely proportional to Wingspan. Why is this? http://avstop.com/ac/flighttrainghandbook/wingtipvortices.html EDIT: ...
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11 votes
3 answers
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Can the MH-60 helicopter fly without one or all of the stabilators?

The MH-60R helicopter has a horizontal Stabilator that consists of three subassemblies, RH Stabilator, LH Stabilator, and Center Stabilator. Can the aircraft fly without the RH Stabilator? Can the ...
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Will control surfaces on a plane be less efficient at a higher altitude?

I may be wrong but I learned that control surfaces depends on the air flow to work properly, and that airliners have a higher cruise altitude because of the less dense atmosphere, improving the fuel ...
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6 votes
1 answer
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How does rudder size influence its ability to produce lateral lift?

Does anyone know how the area, height and width of a rudder affect how well it provides lateral lift? I've heard that the most effective rudders are around 35% of the vertical stabiliser MAC but is ...
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6 votes
4 answers
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Why don't airliners have rudders on the winglets?

There are a couple airplanes out there that use the winglet as the rudder, but why doesn't the winglet have a rudder on it to increase the turn of the aircraft?
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4 votes
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Is there a relationship between control surface deflection and a particular turn radius or bank angle?

I am making a project which includes automation of aileron, rudder and elevator deflection. Is there a quantifiable relation which can tell me the amount of deflection required for any radius of ...
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10 votes
3 answers
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Has anyone researched or built an aircraft that controls pitch and roll by pumping liquid within the airframe?

I am confident I have seen an article couple years ago about a "static surface aircraft" (or at least a concept of it) with no control surfaces, which uses a "wet mass" to adjust its roll and pitch. ...
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5 votes
2 answers
447 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?
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4 votes
2 answers
655 views

How do linear actuators for flight controls work in fighter jets?

I've built some rc planes and know that in order to control an aileron in a rc plane, that you need a servo, a control horn(sticking out of the aileron), and a pushrod. However, I was wondering how ...
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3 votes
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Why aren't tilting propellers used as an alternative for ailerons or elevators?

I was wondering what are the reasons for not using tilted propellers fixed to ailerons/elevators/elevons? Or even on wings with no control surfaces at all? Wouldn't the 2nd way of thrust vectoring ...
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2 votes
2 answers
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How to calculate aileron deflection for achieving similar roll dynamics at thin and dense air?

my question is inspired by projects like Perlan etc when one is trying to fly in thin air with a glider. It is well known that at high altitude (say 10-20km) aircraft control becomes 'sluggish'. ...
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11 votes
1 answer
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What aircraft had the first pilot-assisted controls?

This question about regulations regarding hydraulic flight controls got me thinking about the history of hydraulic or pilot-assisted controls. As aircraft get larger the control surfaces must grow ...
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1 answer
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Is the location of an aircraft spoiler really that vital?

I was wondering that spoilers in most of the aircraft are always placed aft (towards the tail) the CG location. Why aren't they placed ahead of the wings or near the nose of the aircraft? The same is ...
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8 votes
3 answers
779 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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8 votes
2 answers
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What are advantages and disadvantages of flaperons?

What are some advantages and disadvantages of flaperons? Do they cause some issues or are they top-notch reliable?
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12 votes
1 answer
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Does the B-1B Lancer have controllable canards?

These three pictures shows the B-1B Lancer's canards and its elevators. I am not sure to call that feature a canard as the jet also has elevators. In my limited understanding, canard and elevator are ...
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12 votes
8 answers
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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?
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9 votes
4 answers
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Is a monobloc variable incidence wing viable (updated)?

Could this be a viable way to control roll on an aerobatic airplane, using some sort of tab to control a monobloc variable incidence wing? Both wings are mechanically linked together in order to only ...
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7 votes
2 answers
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What are the advantages and disadvantages of ruddervators?

Can someone clearly explain the advantages and disadvantages of ruddervators? I cannot find the answer anywhere else.
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2 votes
2 answers
903 views

In F-16 the pilot or FLCS , use the rudder to address the adverse yaw effects in direction of roll during an aileron roll? or 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 ...
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2 votes
1 answer
219 views

Do all Bombardier jets have manual reversion?

Whatever CRJ 700 or Learjet 35A/45XR. Do these aircraft have full manual reversion? Can you operate the flying surfaces in a hydraulic failure? These aircraft are very small – even ...
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1 vote
1 answer
1k views

How much force is produced by control surfaces?

Context: For some context, I'm a game developer and I'm building a flight sim game. My goal is to have realistic -- not arcade -- physics. The game is in Unity. Unity handles the actual application ...
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18 votes
3 answers
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How do elevons work to roll a flying wing?

I have an RC Flying Wing that uses elevons for control. To go up both elevons move upwards and the wing pitches up. Both go down and the wing pitches down. I’m OK with this. However, if I want to ...
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11 votes
3 answers
981 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 ...
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10 votes
1 answer
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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 ...
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10 votes
2 answers
1k views

Why do gliders have bungee cords in the control systems and what do they do? Are they on all control surfaces? What about ultralights?

Why do gliders have bungee cords in the control systems and what do they do? Are they on all control surfaces? Why don't ultralights have them?
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9 votes
2 answers
340 views

How long does it take on average for a control surface to deflect by one degree?

I know this should vary quite a bit (because of aircraft size / use / build / actuation / control surface weight), but I was wondering if anyone here could ball-park some numbers on how long it would ...
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6 votes
2 answers
633 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?
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6 votes
1 answer
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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 ...
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5 votes
3 answers
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Can large airliners such as a 747 maneuver without electricity?

Small aircraft have the flight controls physically linked to control surfaces by some kind of cable and pulley system. For a large aircraft such as a 747, are the control systems mechanically aided ...
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5 votes
2 answers
665 views

What, if any, would be the most correct term for the aerodynamic flight control surfaces of SpaceX's Starship?

SpaceX's Starship uses a unique flight control scheme during descent that I have not seen anywhere except with skydivers: it falls straight down belly-first using four aerodynamic control surfaces at ...
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5 votes
2 answers
5k views

How do A320 pilots trim?

So, I am very familiar with the 737NG, and there is a trim switch on the yoke for vertical trim. However, I can't seem to locate this trim switch in the A320. Is there a trim switch on the joystick in ...
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3 votes
1 answer
127 views

How should the maximum output force of the actuator be chosen?

If the hinge moments of the control surfaces of an aircraft are given, how should the maximum output force of the actuator be chosen? Is there any standard or reference?
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3 votes
3 answers
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Is it correct to say "the up-elevator position decreases the camber of the elevator"?

Aft movement of the control column deflects the trailing edge of the elevator surface up. This is usually referred to as the up-elevator position. The up-elevator position decreases the camber ...
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3 votes
2 answers
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What is the purpose of the extra horizontal and vertical surfaces on the tail of the Beechcraft 1900? [duplicate]

I am building a very large(11ft span) twin engine RC airplane that is loosely based on the Beechcraft 1900D design. I can't help but notice the extra horizontal surfaces sticking out of the aft ...
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2 votes
1 answer
219 views

Do the stabilators on the F/A-18 also have a roll function similar to the F-22?

I'm curious about the F/A-18C. I know it has ailerons, but they seem too small to be greatly effective at low speeds. Do the stabilators have a roll function as well? If so, is there a speed at which ...
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2 votes
1 answer
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Does it make sense to use a canard in combination with a conventional aft elevator control surface?

I am designing a UAV and have settled on a canard design. However, I’m curious whether it would be helpful to have a typical horizontal stabilizer behind the wing as well as a canard wing in front of ...
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2 votes
4 answers
754 views

Did the Wright brothers discover the three-axis control system for airplanes/gliders and the adverse yaw?

1) Various sites like this one: Orville and Wilbur Wright, The Inventors of the 3-axis Flight Control System, 9 Months before their powered flight at Kitty Hawk say that the two brothers invented the ...
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