Aviation BasicAircraft Controls

Revision – Name the components

Lateral Longitudinal & Vertical AxisThe family car can only be controlled around one axis

Which of these?

Need to know the aircraft terminology

One control that is often forgotten is the throttle, it is perhaps the most important

Increase the speed and the angle of attack changes due to the increased lift causing the aircraft to climb. Conversely lowering the speed reduces lift and causes a dive

The elevator controls pitch about the lateral axis. on small aircraft, the elevator is connected to the control column in the flight deck by a series of mechanical linkages. Aft movement of the control column deflects the trailing edge of the elevator surface up. This is usually referred to as up “elevator.”

Typical schematic drawing of mechanical elevator operation

Larger aircraft use a hydraulic system and or electrical servos to operate controls

Control surfaces are balanced so that the hinge point is the centre of gravity

This helps prevent “flutter”

Typical slab tail arrangement

Rudder controls yaw around the normal axisand is operated by the rudder pedals

The rudder pedals also control steering when the aircraft is taxying

Beechcraft Bonanza V35.

On a “V tail”, the movable surfaces, are usually called ruddervators. They are connected through a special linkage that allows the control wheel to move both surfaces simultaneously. On the other hand, displacement of the rudder pedals moves the surfaces differentially, thereby providing directional control.

Ailerons control roll around the longitudinal axis, and are probably the most complicated of the 3 axis control system

Differential ailerons move further up than down when actuated from the control column

Frise-type ailerons create a slot between the wing and the aileron to inject laminar flow around the aileron surface

In reality, to turn an aircraft one would bank turning the aircraft towards the wing being lowered. Some systems have the ailerons connected to the rudder to assist the turn

Flaperons on a Skystar Kitfox MK 7.

On some light aircraft the ailerons run the full length of the wings and incorporate Flaps operating both as flaps and ailerons

Secondary controls

Flaps and high lift devices

Flaps

Flaps are high-lift devices. Diagram shows the most common used on aircraft

Leading Edge Devices

Triple slotted Fowler Flap commonly used on wide bodies aircraft

Trim SystemsAlthough an aircraft can be operated throughout a wide range of attitudes, airspeeds, and power settings, it can be designed to fly hands-off within only a very limited combination of these variables. Trim systems are used to relieve the pilot of the need to maintain constant pressure on the flight controls, and usually consist of flight deck controls and small hinged devices attached to the trailing edge of one or more of the primary flight control surfaces. Designed to help minimize a pilot’s workload, trim systems aerodynamically assist movement and position of the flight control surface to which they are attached. Common types of trim systems include trim tabs, balance tabs, antiservo tabs, ground adjustable tabs, and an adjustable stabilizer

Fixed trim tabs are often used on light aircraft and are adjusted during a series of test flights

Spoilers are used to create drag assisting in slowing down a landing aircraft

Spoilers (lift dumpers) are used on gliders