Exercise 22. Read and translate the text.

Text 4.Secondary Control Surfaces

The primary control surfaces are used to direct the airplane around three main axes. Various other control surfaces are used to trim - adjust or balance - the airplane and provide stability in flight. The secondary control surfaces are relatively small airfoils attached to the trailing edges of the primary control surfaces They include the trim tabs, servo-tabs, and balance tabs.

A trim tab is used to correct any tendency of the airplane to abnormal attitude of flight without application of pressure to the control stick or the rudder pedals

The balance tab decreases the force, which must be exerted by the pilot to deflect a primary control surfaces. The balance tab is so connected that when the primary control surface is moved in any direction the tab rotates in the opposite-direction. A servo-tab is used to assist in moving a large primary airfoil and holding it in the desired position with the help of a special servo mechanism.

The secondary control surfaces are actuated by levers, wheels or cranks or by connection with the controls of the primary surfaces.

The elevator trim tab is usually adjustable from inside the cabin in flight by turning a trim wheel or crank.

Trim tabs on the rudder may be either adjustable from inside the plane or they may be small sections that must be adjusted on the ground by bending the section in the proper direction.

The rudder trim tab permits the aircraft to fly straight ahead without pressure on the control wheel or rudder pedals.

Exercise 23. Answer the questions.

1. What are the secondary control surfaces? 2. What do the secondary control surfaces include? 3. What is a trim tab used for? 4. Does the rudder trim lab permit the aircraft to fly straight ahead without pressure on the control wheel or rudder pedals? 5 Is the balance tab so connected that when the primary control surface is moved in any direction the tab rotates in the opposite direction? 6. How does a balance tab work? 7. What arc the secondary control surfaces actuated by? 8. How is the elevator trim tab adjusted? 9. How is the rudder trim tab adjusted?

Exercise 24. Read these terms out loud and translate them.

a) to direct, to control, to trim, to adjust, to balance, to correct, to decrease, to exert, to actuate, to bend, to rotate;

b) axis, stability, airfoil, edge, trim tab, servo-tab, balance tab, tendency,
attitude, application, force, direction, lever, crank, wheel.

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Exercise 21. Translate text 3 in the written form.	\|	Exercise 25. Read and remember these verb combinations.

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