Flight control surfaces

The controls (stick and rudder) for rotary wing aircraft (helicopter or autogyro) accomplish the same motions about the three axes of rotation, but manipulate the rotating flight controls (main rotor disk and tail rotor disk) in a completely different manner.

Hinged control surfaces have the advantage of not causing stresses that are a problem of wing warping and are easier to build into structures.

The rudder also has a secondary effect on bank through moving one wing forward and the other backwards, affecting the lift they produce.

The main control surfaces of a fixed-wing aircraft are attached to the airframe on hinges or tracks so they may move and thus deflect the air stream passing over them.

This redirection of the air stream generates an unbalanced force to rotate the plane about the associated axis.

Ailerons are mounted on the trailing edge of each wing near the wingtips and move in opposite directions.

Centering the control returns the ailerons to the neutral position, maintaining the bank angle.

The aircraft will continue to turn until opposite aileron motion returns the bank angle to zero to fly straight.

Continued application of rudder sustains rolling tendency because the aircraft flying at an angle to the airflow - skidding towards the forward wing.

This effect of the rudder is commonly used in model aircraft where if sufficient dihedral or polyhedral is included in the wing design, primary roll control such as ailerons may be omitted altogether.

The total load factor required to maintain level flight is directly related to the bank angle.

Beyond this angle of bank, the aircraft will suffer an accelerated stall if the pilot attempts to generate enough lift to maintain level flight.

Some aircraft have a tail in the shape of a V, and the moving parts at the back of those combine the functions of elevators and rudder.

On low drag aircraft such as sailplanes, spoilers are used to disrupt airflow over the wing and greatly reduce lift.

Flaps raise the maximum lift coefficient of the aircraft and therefore reduce its stalling speed.

[5] They are used during low speed, high angle of attack flight including take-off and descent for landing.

Some aircraft are equipped with "flaperons", which are more commonly called "inboard ailerons"[citation needed].

Air brakes are usually surfaces that deflect outwards from the fuselage (in most cases symmetrically on opposing sides) into the airstream in order to increase form-drag.

Whilst carrying out certain flight exercises, a lot of trim could be required to maintain the desired angle of attack.

Elevator trim is correlated with the speed of the airflow over the tail, thus airspeed changes to the aircraft require re-trimming.

Any disturbances such as gusts or turbulence will be damped over a short period of time and the aircraft will return to its level flight trimmed airspeed.

Except for very light aircraft, trim tabs on the elevators are unable to provide the force and range of motion desired.

To provide the appropriate trim force the entire horizontal tail plane is made adjustable in pitch.

This allows the pilot to select exactly the right amount of positive or negative lift from the tail plane while reducing drag from the elevators.

It generates a force which tends to increase the surface's deflection thus reducing the control pressure experienced by the pilot.

Aileron trim is to counter the effects of the centre of gravity being displaced from the aircraft centerline.

Moving the control stick to the left moves the aileron in the left wing up, that in the right wing down, making the plane lower the left wing. Pulling on the stick moves the elevators up, making the plane raise the nose. Pressing the right rudder pedal moves the rudder to the right, making the plane turn the nose to the right.
Basic aircraft control surfaces and motion. A)aileron B)control stick C)elevator D)rudder.
"pitch" is a nose-up/nose-down rotation, "roll" is a rotation lifting one wing and lowering the other, "yaw" rotation moves the nose in a left/right direction
Rotation around the three axes
Mnemonics to remember angle names
Flight control surfaces of Boeing 727
Aileron surface
KLM Fokker 70 , showing position of flap and liftdumper flight controls. The liftdumpers are the lifted cream-coloured panels on the wing upper surface (in this picture there are five on the right wing). The flaps are the large drooped surfaces on the trailing edge of the wing.
Wing trailing edge flight control surfaces of a Boeing 747-8 . Top left: All surfaces at neutral position; Top middle: Right aileron is lowered; Top right: spoilers raised during flight; Middle row: Fowler flaps extended (left), extended more (middle), hinged with inboard slotted part hinged even more (right); Bottom row: spoilers raised during landing
Air brakes on the rear fuselage of a Eurowings BAe 146-300
Mass balance protruding from an aileron used to suppress flutter