# Questions tagged [control-surfaces]

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

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### 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 ...
138 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 ...
87 views

### How does the F-16 stabilizer counter the yaw in eventuality of spin?

In a specific state of aerodynamic stall the vertical tail and rudder airflow is blanked by wings, so now it is hard to counter the yaw. However the stabilators will help. How?
1k 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 ...
137 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 ...
1k 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 ...
39 views

### What are typical control surface deflection “rate” limits for transport airplanes?

I was wondering if anyone knows what are some typical control surface/actuator deflection "rate" limits for transport airplanes (i.e. aileron/elevator/rudder deflection rates)? I haven't ...
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### Why does the zeppelin NT tail use 3 fins?

I don't if I use the correct vocabulary. By "fin", I mean the control surface at the tail of the airship. As a control surface, it contains a moving part. As airship used to have at least 4 fins at ...
166 views

### In an F-18, how do rudders deflect during cross winds and gusts? Can rudders be deflected by different angles?

Deflection of rudders can balance moment about the centre of gravity. I have thought of non-symmetric deflection of rudders so that net sideward force is create to balance the moment about the center ...
1k views

### In simple mechanical stick linkages, is there crosstalk between the aileron and the elevator movement?

The background story: I'm an aviation enthusiast (who has played a lot of sim in his life and will play lots more :D) but I've never actually flown any plane myself, as in, actually used the controls ...
322 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 ...
78 views

### How is the control surface configuration of predator/reaper for redundancy system?

In commercial aircraft like Airbus or Boeing, there are several control surfaces that work in the same function such as for roll control capability, the control surfaces are aileron and spoiler. Also ...
121 views

### How is roll control achieved for the space ship two?

When looking at scaled composite 339 space ship two I fail to see control surfaces on the trailing edge of the wing. For me, it seems that the only moving surface on the wing is the feathering ...
604 views

### What are typical control surface deflections?

How can I tell what a reasonable control surface deflection is? For example, is a 10 deg aileron deflection reasonable? Or a 0.5 degree aileron deflection? Is that too little? Too much? Same ...
262 views

### How does a delta wing deal with supersonic boundary separation?

The question Why most of the supersonic or fighter aircraft use all-moving control surfaces? emphasis the importance of all moving stabilator for supersonic aircraft. Many supersonic aircrafts ...
95 views

### In F/A-18, where the servo-loop closure is accomplished?

In the flight control system of F/A-18, where is the servo-loop closed? I mean which of these two scenarios happen: 1-The position of the actuator and servo-valve ram are sent to the flight control ...
296 views

### Aerodynamics of Flight Control Surfaces

From what it appears to me, flight control surfaces seem to be taken for granted. In terms of how they actually work and what kind of physical outputs they give in terms of forces and such. Take for ...
200 views

### Where is the control loop of the actuator closed?

When electro-hydraulic servo-actuators are used for the actuation of control surfaces in aircraft, linear variable differential transformers (LVDTs) are used for position or velocity feedback. There ...
469 views

### Are there roll control devices other than ailerons?

With the little that I've learnt about aeroplanes, I know that the aileron is the control surface that a pilot use to roll the plane by decreasing the lift of one wing and increasing the lift of the ...
812 views

### Why would engine fire cause loss of control?

I was wondering why engine fire would cause of loss of control or crash. There is loss of power and even drag. But could some expert please expand on the troubles of a engine fire?
86 views

### what are the no load rates of f-16 control surfaces?

What are the no-load rates for the control surfaces of f-16 like flaperon,leading edge flap and horizontal and vertical stabs?
537 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 ...
220 views

### What hardware standards should the flight control computer pass?

There are some standards for each part of the aircraft like actuators, sensors,... I could not find one for the flight control computer hardware. For example what are the environmental tests, or any ...
356 views

### Why were trim tabs invented?

I understand the need for a trimming mechanism, but why use a secondary control surface placed on top of the first, when you could just adjust the resting position of the aileron/elevator/rudder ...
50 views

### Does the SAS (stability augmentation system) actuators of f-14 use jet-pipe or flapper-nozzle technology?

F-14 uses electrohydraulic servo actuators for its SAS. What type of hydraulic amplification is used in F-14? jet-pipe, flapper-nozzle or something else?
181 views

### How many actuators does the F-35 have for each primary control surface?

How many actuators does the F-35 have for each primary control surface like rudder, stabilator or aileron? And is it active/active or active/standby?
103 views

### What factors should be considered to select jet-pipe or flapper-nozzle technology for a primary control surface?

How is the servovalve mechanism chosen between these two mechanisms? what are their advantages and drawbacks?
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### How is the bandwidth of an actuator selected for a primary flight control surface?

How the bandwidth of an actuator is selected for a primary flight control surface? Is there any standard? Based on what factors this decision is made?
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### 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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### 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 ...
45 views

### Is there a general standard for servo actuators?

It is said in the standard AS94900 that the standard ARP490 should be considered for the actuators of the control surfaces in the aircraft. However, this standard is on servo valves and not servo ...
167 views

### Does every control surface need to have a counterweight?

Is it not a good idea to balance all control surfaces, no matter what they weigh? I am building a small plane, with small control surfaces. There are many of the same type of plane flying. Most have ...
391 views

### What are these blades on the engine cowling of a Wittman Tailwind?

The Florida Air Museum in Lakeland has a Wittman W-8 Tailwind with four wooden, propeller-like blades on the engine cowling: Source: own work What are the blades for? It's an experimental aircraft ...
4k views

### What is the difference between a trim tab and a servo tab?

They both seem very similar but can someone please explain their main differences and principle of operation?
359 views

### What does “wraparound” mean in the context of flight controls?

In the references regarding the flight control (for example in F-16) I see the word "wraparound". For example "Rudder coil wraparound", "IBU pitch wraparound", "IBU lateral wraparound"or "AMUX bus ...
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### Why do military jets sometimes have elevators in a depressed position when parked?

Why do they have elevators in such a position as if the joystick is pushed forward, even though there's nobody inside the cockpit?
3k views

### Do jackscrews suffer from blowdown?

With hydraulic control surfaces, at high airspeeds, there is a point where aerodynamic loads exceed the capability of the actuators. This limits control authority and can result in the control surface ...