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 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
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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 rotorsare 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.
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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. 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.
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 13
The Airplane Designers
Preparing to Read
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