In the text find the main function of a) the main rotor b) the tail rotor

Find in the text pros and cons of using a helicopter.

3. Match the given titles with the corresponding paragraphs. Whatch out! There is an extra title.

1. Civil helicopters

2. Military helicopters

3. Helicopter advantages

4. Tail rotor

5. Creating lift

6. Helicopter features

7. Air ambulance

8. Use of helicopters

9. Helicopter disadvantages

10. Aerial crane

11. Aerial firefighting

12. Helicopters help police.

Give your own definitions for the words from the box.

Hovering flight; sling; aerial crane; fuel tank; rotor blade; loading equipment, fuel consumption.

Read the text again and decide if these statements are true or false. Correct the false ones.

1. Helicopters are fixed-wing aircraft.

2. Rotating blades send the air stream downward thus creating lift.

3. Helicopters can operate only from well prepared runways.

4. Helicopters are able to load and unload without landing.

5. Helicopters are used for military and peaceful purposes.

6. Function of the tail rotor is to produce additional lifting force.

7. Helicopters can carry loads by means of slings.

Look at the text and ask 15 questions to the text.

Vocabulary Focus

Match words in A with words B to form the word combinations.

A B

create range

take off consumption

rotating attack

counteract lift

loading blades

fuel equipment

long vertically

aerial torque

Make up sentences using word combinations from ex.1.

Match the synonyms.

A B

helicopter equip

mount create

airstrip runway

traditional rotary-wing aircraft

restrict conventional

auxiliary limit

disadvantage additional

generate drawback

Fill in the table with the proper part of speech derived from the word given.

Noun	Verb	Adjective (Participle)
		counteractive
rotation
		equipped
	consume
building
treatment
		achieved
transport

Writing

Translate in a written form.

Contra-rotating rotors, are rotorcraft configurations with a pair or more of large horizontal rotors turning in opposite directions to counteract the effects of torque on the aircraft without relying on an antitorque tail rotor. Primarily, there are three common configurations that utilize the contra-rotating effect to benefit the rotorcraft; tandem rotors are two rotors with one mounted behind the other, coaxial rotors are two rotors that are mounted one above the other with the same axis, and intermeshing rotors are two rotors that are mounted close to each other at enough angle to allow the rotors to intermesh over the top of the aircraft.

Tandem rotors are two horizontal main rotor assemblies mounted one behind the other with the rear rotor mounted slightly higher than the front rotor. Tandem rotors achieve pitch attitude changes to accelerate and decelerate the helicopter through a process called differential collective pitch. To pitch forward and accelerate, the rear rotor increases collective pitch, raising the tail and the front rotor decreases collective pitch, simultaneously dipping the nose. To pitch upward while decelerating (or moving rearward), the front rotor increases collective pitch to raise the nose and the rear rotor decreases collective pitch to lower the tail. Yaw control is developed through opposing cyclic pitch in each rotor; to pivot right, the front rotor tilts right and the rear rotor tilts left, and to pivot left, the front rotor tilts left and the rear rotor tilts right.

Coaxial rotors are a pair of rotors turning in opposite directions, but mounted on a mast, with the same axis of rotation, one above the other. The advantage of the coaxial rotor is that, in forward flight, the lift provided by the advancing halves of each rotor compensates for the retreating half of the other, eliminating one of the key effects of dissymmetry of lift; retreating blade stall. However, other design considerations plague coaxial rotors. There is an increased mechanical complexity of the rotor system because it requires linkages and swashplates for two rotor systems. Add that each rotor system needs to be turned in opposite directions means that the mast itself is more complex, and provisions for making pitch changes to the upper rotor system must pass through the lower rotor system.

Intermeshing rotors on a helicopter are a set of two rotors turning in opposite directions, with each rotor mast mounted on the helicopter with a slight angle to the other so that the blades intermesh without colliding. Intermeshing rotors have high stability and powerful lifting capability.

Speaking

You are to organize transportation of a scientific expedition to the impassable forest. What kind of aircraft will you choose? Give your reasons. Tell your partners about your choice.

UNIT 14

The Plane Makers

Preparing to Read

Give a definition of the term “plane maker”. Compare your definition with your partner.

Tick the words which come to your mind when you think of the plane makers.

1. reliability

2. safety

3. assembly

4. test

5. professional skills

6. strength

7. freezing point