Dialogue 1. Primary Flight Control Surfaces

T. One can say, that empennage is one of the principal structural units of the aircraft

What do you know about it?

S. Tail assembly is located at the rear of any aircraft. The tail unit consists of symmetrical airfoil sections: vertical and horizontal surfaces. Each of them is divided into two parts, the front (fixed) and the rear (movable, in the form of a flap). The vertical surface is known as «fin». The horizontal surface is called «stabilizer». The tail unit provides directional and longitudinal stability of the aircraft in flight.

T. You are quite right. Look at the picture. Can you point the tail unit and its sections?

S. Sure. Here they are.

T. O.K. But today our topic isn't just tail assembly. We'll be speaking about primary flight control surfaces. The term «primary flight control surfaces» includes elevators and rudder. Elevators and rudder are the elements of the empennage, and ailerons are the parts of the wing. Let's consider the rudder more concretely. Look at this picture.

At the rear of the airplane is the tail assembly or empennage. So, this is the tail assembly. It is composed of a fin which is not movable, and the rudder, which is attached to the fin. Here it is.

	T. The rudder is a movable part, hinged to the trailing edge of the tail's vertical fin. It is designed to control the yawing action around the vertical axis of the aircraft. The rudder can be deflected to the right or to the left or lie in line with the fin. If it is necessary to turn the airplane to the left, the rudder is pushed to the left. So, what can you say about the rudder?

S. The rudder is movable and, if it is turned towards the right while the tail turns towards the left, the nose of the airplane turns towards the right. So that the plane makes a right turn.

T. That is very good. What does the nose of the plane do when you turn the plane towards the right?

S. The nose of the plane turns towards the right.

T. Quite so. I f the nose of the aircraft turns towards the right, in which direction does the tail turn?

S. The tail turns towards the left.

T. Does the airplane make a right turn?

S. Yes, it does.

T. You are quite right. The control surfaces are actuated by means of control mechanism, which consists of the controls in the cockpit together with the linkage and

accessories.

Remember these terms: to actuate- приводити в дію controls- органи керування linkage - проводка керування accessories- допоміжні агрегати

T. Look at this picture. This is the flight control system. The control stick or column and rudder pedals through the linkage actuate all control surfaces. The linkage consists of cables with turnbuckles. The cables are guided through fair-leads and over pulleys.

The word-combinations " control stick" and " control column" have the same meaning. They are translated as " ручка керування". Let's translate the new terms:

turnbuckle – стяжна муфта

fair-lead – вивідна трубка

pulley – блок, шків, ролик

rudder pedal – педаль руля повороту.

Т. Let’s translate this passage.

Всі органи керування приводяться в дію ручкою керування та педалями руля повороту за допомогою проводки керування. Проводка керування складається з тросів зі стяжними муфтами. Троси приводяться в дію за допомогою вивідних трубок і шківів.

Т. So by pushing the left pedal, the pilot makes the rudder move to the left, causing the airplane to turn to the left around its vertical axis. Pressure on the right pedal (turns the airplane to the right. The primary purpose of the rudder is to coordinate with the ailerons the movement of the aircraft when the plane is banked. Look at this picture.

These are elevators. The elevators are movable airfoils. They are attached to the trailing edge of the tail's horizontal stabilizer. Do they control the pitch?

S. Yes, they do. They control the pitch that is the rotation of the aircraft around the lateral or pitch axis. To cause the airplane to climb it is necessary to deflect them upward. When the elevators are lowered the aircraft begins to descend.

T. You are quite right. So, they can deflect downwards and upwards.