While aircraft may differ in designs, shapes, and also in terms of the powerplant that they employ, the basic controls of all conventional aircraft stay the same and they are called the Primary Flight Controls. These controls are universal for all aircraft and regulate its basic movements. Nevertheless, before we can explore these controls we need to understand certain principles of flight that govern the use of the Primary Flight Controls.
The Axis of Rotation
As we know that an aircraft has the ability to maneuver about all three dimensions, that is to say that an airplane can move vertically or pitch, move horizontally or yaw, or move in a turning manner or roll. When an aircraft pitches, it moves about its Lateral Axis, and when it rolls it moves about its Longitudinal Axis; similarly when it yaws or changes direction, it moves about is Vertical or Normal Axis. These Axis about which an aircraft can move are called the Axis of Rotation of an aircraft.
Aerofoil and the Camber
The wings, horizontal stabilizer, and other structures of an aircraft are specially shaped to ensure a smooth flow of the air over them, and also to generate lift in the process. These aerodynamic shapes are called Aerofoils, and the amount of lift that they generate depends on many different factors including shape, size, and thickness. A Camber of an Aerofoil is a symmetrical line from the trailing edge to the leading edge of that Aerofoil. Increase in the camber of an Aerofoil increases the lift being produced by that particular Aerofoil.
The Three Basic or Primary Flight Controls in an Aircraft
Ailerons are movable part of the wings and are attached to the trailing portion on the outer sides of both the wings. The rolling motion of an aircraft about the Longitudinal Axis is controlled by ailerons, which are activated through the control column.
Elevators are movable parts of the Tailplane and are attached towards the back of the Tailplain. Elevators are also controlled through the control column and these are responsible for the pitching movement of an aircraft about its Lateral Axis.
Rudders control the directional or yaw movement of an aircraft that is about the Normal or Vertical Axis. Rudders are controlled through the rudder pedals provided at the feet of the pilot and act through moveable back portion of the vertical fin of the tail of the aircraft.
What Do the Primary Controls Do?
The primary flight controls are attached to the regular aircraft surface through hinges, and are able to move separately from the wings, tailplane, and the horizontal stabilizer. These primary controls are aerodynamically shaped like Aerofoils, and through their angular movement about the hinges alter the original shape of the attached surface. Since in order to make this happen the control column is deflected to one side, the primary control deflects downward on that side. This change in shape increases the camber on the deflected side of the aerofoil thus increasing the lift on that side. The result is a movement in the intended direction, taking clue from the correct control input by the pilot. If the elevators are deflected downwards by pulling the control column backwards, the increased lift will make the aircraft to pitch up. Similarly, Ailerons and the Rudders control the rolling and yawing movements of the aircraft respectively.
The Primary Flight Controls are the main controls for flying an aircraft, and almost every type of flying involves their use; the very first lessons that a pilot gets on flying are about the correct use of the Primary Flight Controls.