Answer the questions to the text.

a) What forces act on an aeroplane in straight-and-level, unaccelerated flight?

b) What is the engine-propeller-combination designed for?

c) What will any inequality between lift and weight result in?

d) What will any inequality between thrust and drag result in?

e) What is an airfoil? Give examples of airfoils.

f) What is the chord?

g) What is the angle of incidence?

h) What is the relative wind?

i) What is the angle of attack?

3. Which of the statements are true and which ones are false? Correct the false ones.

a) Lift is the upward acting force.

b) Weight is the upward acting force.

c) Thrust is the downward acting force.

d) Drag is the forward acting force.

e) Lift opposes gravity and thrust opposes drag.

f) Thrust and lift are artificially created forces used to overcome the forces of nature.

g) In straight-and-level, unaccelerated flight lift equals thrust and weight equals drag.

h) Wings, horizontal tail surfaces, vertical tail surfaces and propellers are all examples of airfoils.

i) The forward part of an airfoil is called the trailing edge.

j) The angle of attack is the angle formed by the longitudinal axis of the aeroplane and the chord of the wing.

k) The relative wind is the direction of the airflow with respect to the wing.

l) Take off should be made along the wind.

m) The airfoil is designed to increase the velocity of the airflow above its surface.

4. Translate into your language and back into English.

straight-and-level flight;

unaccelerated flight;

lift;

thrust;

weight;

drag;

gravity;

wind resistance;

upward (downward, forward, backward) acting force;

artificially created forces;

engine-propeller combination;

acceleration;

deceleration;

airfoil;

wing;

horizontal tail surfaces;

vertical tail surfaces;

leading edge;

trailing edge;

chord;

angle of incidence;

longitudinal axis;

relative wind;

flight path;

takeoff roll;

angle of attack;

velocity of the airflow;

decreasing pressure;

simultaneously.