All aircraft are designed to fly through the air. But not all of them fly the same way. In fact, there are two types of aircraft. One is called lighter-than-air. The other is known as heavier-than-air. A lighter-than-air craft is able to float. It can become lighter in weight than the air around it. A circus balloon is a simple example of this type of craft. Before it gets filled, the balloon doesnt move. Its weight keeps it down. But fill the bag with helium gas, and the balloon lifts up. Why does this happen? The reason is that helium is much lighter than air.
Why Kites Fly
A heavier-than-air craft is different. It always stays heavier than the air around it. This type of craft flies for another reason. Its surfaces cause moving air to lift up the craft. A simple heavier-than air craft is a kite. Kites come in many shapes and sizes. But they are all made to lift up in the wind. The kites people around the world fly for fun are named after the kite bird. This type of bird is also found all over the world.
Hot-Air Balloons
Most of us have seen them. Big and colorful, hot-air balloons carry people for long rides through the air. How do they do it? These lighter-than-air craft work in several ways. First, every hot-air balloon has an air-filled bag, or envelope. Because of its large size, the bag can move aside a lot of air. But air moved to another place pushes back. In fact, this displaced air presses so hard that it keeps the bag afloat. In other words, the bag is buoyant. But the basket tied to the bag stays on the ground. Its cargo of equipment and people is heavy.
To make the hot-air balloon go up, the pilot turns on a burner under the bag. The burner creates a flame. Hot air quickly rises into the huge bag. This heats up the air molecules inside. They start moving faster. Also, some of them escape through the bottom of the bag. That leaves fewer molecules inside. They are farther apart, too. The inside air, then, is less dense than the air outside, and it weighs less. The result? The hot-air balloon rises. To lower the hot-air balloon, the pilot turns off the burner. The air inside the bag gets cooler. That means the air molecules slow down. They also move closer together. Soon theres room for outside air to re-enter the bag. More air molecules inside make the air in the bag denserand heavier. So the craft comes down.
Floating Airships
Hot-air balloons can fly, but they cannot be steered. They simply float in whatever direction the wind takes them. An airship is a lighter than-air aircraft, too. But unlike a hot air balloon, the airship has an engine and fins. These allow the ship to be steered in the direction where the pilot wants it to go. The envelope of an airship is long and rounded. Usually helium gas issued to inflate it. The helium is sealed inside. Since helium is lighter than air, the envelope stays afloat.
Exercises
Vocabulary
1. Transcribe the words:
craft, lighter-than-air, heavier-than-air, float, weight, circus balloon, helium gas, kite, hot-air balloon, air-filled bag, envelope, keep afloat, buoyant, burner, molecules, dense, steer, engine, fin, issue, inflate
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2. Match the words from the texts (1-5) with their synonyms (A-E):
| 1 | steer | A | powered balloon |
| 2 | airship | B | fly |
| 3 | shape | C | skin |
| 4 | envelope | D | outline |
| 5 | engine | E | motor |
3. Explain in English and then translate the following words and expressions into Russian:
to fly through the air, a lighter-than-air craft, weight keeps it down, hot-air balloons, an air-filled bag
4. Match the words from the texts (1-10) with the definitions (A-J):
| 1 | airship | A | the structure within a balloon or non-rigid airship containing the gas |
| 2 | balloon | B | a part of a cooker, lamp, etc. that emits a flame |
| 3 | kite | C | a flexible container with an opening |
| 4 | bag | D | a toy consisting of a light frame with thin material stretched over it, flown in the wind at the end of a long string |
| 5 | envelope | E | able to keep something afloat |
| 6 | buoyant | F | a power-driven aircraft that is kept buoyant by a body of gas (usually helium, formerly hydrogen) which is lighter than air |
| 7 | burner | G | a group of atoms bonded together, representing the smallest fundamental unit of a chemical compound that can take part in a chemical reaction |
| 8 | molecule | H | a large bag filled with hot air or gas to make it rise in the air, typically one carrying a basket for passengers |
| 9 | steer | I | a small flattened projecting surface or attachment on an aircraft, rocket, or car, for providing aerodynamic stability |
| 10 | fin | J | guide or control the movement of (a vehicle, vessel, or aircraft), for example by turning a wheel or operating a rudder |
5. Find in the texts the English equivalents for the following words and expressions:
(1) two kinds of airplane, (2) a vehicle can fly, (3) sample,(4) upside, (5) contour, (6) dimension, (7) gas-bag, (8) throw back, (9) decelerate, (10) to return into the bag, (11) drive, (12) sail, (13) blow, (14) leave out, (15) shell
6. Complete the text with the words from the box
| drag | flown | passengers | pressure |
| forces | direction | aerial | wing |
| lift | steerable | applications | aircraft |
A kite is a tethered (1). The necessary (2) that makes the kite wing fly is generated when air flows over and under the kite's (3), producing low (4) above the wing and high pressure below it. This deflection also generates horizontal (5) along the (6) of the wind. Kites may be (7) for recreation, art or other practical uses. Sport kites can be flown in (8) ballet, sometimes as part of a competition. Power kites are multi-line (9) kites designed to generate large (10) which can be used to power activities such as kite surfing, kite fishing and a new trend snow kiting. Kites towed behind boats can lift (11) which has had useful military (12) in the past.
7. Find in the texts the English equivalents for the following words and expressions
(1) , , (2) , , (3) , (4) , (5) , (6) , , (7) , (8) , , (9) , (10) .
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8. Answer the following questions. Begin your answers with such introductory phrases as: as far as I know; as far as I remember; to my mind; certainly; it's hard to tell; probably; of course; if I am not mistaken, etc.
1) What are aircrafts designed for?
2) What types of aircraft are there?
3) Why does a circus balloon fly?
4) What are kites made for?
5) How do hot-air balloons fly?
6) What is a burner used for?
7) Can any type of aircraft be steered? Which one?
9. Translate the following sentences into English:
1. , . : , .
2. , . , .
3. . , , .
4. , , . .
5. , , . .
Speaking
Give a 5-minute presentation on one of the following topics. Use the Extemporaneous Method of Delivery.
1) Hot-Air Balloons
2) Floating Airships
3) Kites
| The Extemporaneous Method of Delivery This method is described as the most effective one. It is based on: ● thorough preparation; ● memorizing the main ideas; ● abbreviating the manuscript to a number of key words and phrases. Advantages: ● this method allows you great flexibility (you are not fixed on the exact wording ➔you are free to extemporize depending on the feedback from the audience); ● with this method it is easy to be natural; ● this method comes closest to enlarged conversation, which is an ideal form of public speaking; ● your physical freedom (you are not tired to the script➔you can move freely, use body language and interact with the audience). [ : Learning to Speak in Public, 2002] |
Writing
Do some research and write a 100-200 word history of airships (kites, balloons).
Unit 9
What is an airplane
What is the difference between aircraft and airplane? Aircraft is the more general term, and refers to any heavier-than-air craft that is supported by its own buoyancy or by the action of air on its structures. An airplane is a heavier-than-air craft that is propelled by an engine and uses fixed aerodynamic surfaces (i.e. wings) to generate lift. So, every airplane is an aircraft, but not every aircraft is an airplane! Gliders are aircraft that are not airplanes. The Space Shuttle is definitely an aircraft, but it is not an airplane. It does not carry engines for propulsion. Helicopters are also aircraft that are not airplanes because their aerodynamic surfaces are not fixed - they rotate.
Why are there so many different types of airplanes?
The characteristic that most readily identifies the type, performance and purpose of an airplane is the shape of its wings. There are four basic wing types: straight wings, sweep wings (forward-sweep/sweepback), delta wings and the swing-wing (or variable sweep wing). Each shape allows for premium performance at different altitudes and at different speeds.
Another important discriminator between airplanes is speed. Airplanes fly at subsonic, transonic, supersonic and hypersonic speeds. These speed classifications are called the "regimes" of flight. The suffix -sonic refers to the speed of sound, which is dependent on altitude and atmospheric conditions (nominally 340 meters per second). "Mach" is a term used to specify how many times the speed of sound an aircraft is traveling. Mach 1 is one times the speed of sound. Mach 2 is twice the speed of sound, and so on. Mach numbers less than 1 are speeds less than the speed of sound.
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Subsonic refers to all speeds less than Mach 1. Transonic refers to all speeds from approximately Mach.9 to Mach 1.5 - that is, the speeds at which an aircraft is going through the speed of sound or "breaking the sound barrier". Supersonic refers to all speeds greater than the speed of sound, which is the same as saying all speeds above Mach 1. Hypersonic refers to all speeds greater than Mach 5. Note that an aircraft flying at hypersonic speeds can also be said to be flying at supersonic speeds.
Every modern aircraft that is built today is built for a specific purpose. Airplanes are designed for different altitudes, different speeds, different weight-carrying capacities, and different performance. Jet fighters are relatively lightweight, highly maneuverable and very fast.
They are designed to carry a relatively small amount of weight, including fuel, which necessitates refueling on long flights. Passenger airplanes are larger, carry more weight, and can fly longer distances. However, they are less maneuverable and slower than jet fighters. Other aircraft like the SR-71, are designed to fly at very high altitudes and high speeds for very long periods of time. Every aircraft fills a particular niche in the gigantic matrix that is modern aviation.
Exercises
Vocabulary
1. Memorize the following vocabulary units.
buoyancy, fixed aerodynamic surfaces, propulsion, performance, hypersonic, jet fighter, fuel, refueling, straight wing, sweep wing, subsonic, transonic, supersonic
2. Transcribe the words:
aircraft, airplane, buoyancy, aerodynamic, propulsion, hypersonic, altitude, design
3. Match the words from the texts (1-5) with their synonyms (A-E):
| 1 | speed | A | sailplane |
| 2 | buoyancy | B | productivity |
| 3 | glider | C | velocity |
| 4 | performance | D | carrying capacity |
| 5 | maneuverable | E | easy-to-handle |
4. Match the words from the texts (1-10) with the definitions (A-J):
| 1 | craft | A | pushing forwards |
| 2 | altitude | B | a type of aircraft which derives both lift and propulsion from one or two sets of horizontally revolving overhead rotors |
| 3 | lift | C | spaceship |
| 4 | propulsion | D | the capabilities of a machine, product, or vehicle |
| 5 | helicopter | E | a rigid horizontal structure that projects from both sides of an aircraft and supports it in the air |
| 6 | performance | F | upward force exerted by the air on an aerofoil or other structure |
| 7 | wing | G | rapidity of movement or action |
| 8 | speed | H | material such as coal, gas, or oil that is burned to produce heat or power |
| 9 | fuel | I | a fast military aircraft designed for attacking other aircraft |
| 10 | fighter | J | the height of an object or point in relation to sea level or ground level |
5. Explain in English and translate the words and expressions into Russian:
airplane, aircraft, propulsion, regimes of flight, hypersonic speed, sound barrier, passenger airplane
6. Complete the text with the words from the box
| fixed | shape | engines | pressure |
| wings | surface | propeller. | forward |
| blades | air | nose | steer |
An airplane is a heavier-than-air craft with (1) wings (that is, wings that dont move) and one or more (2). In many airplanes, the engine turns a (3). Propellers are found mostly on a planes (4) or (5). The propeller is made of several (6) around a center, or hub. The front (7) of each blade is rounded. It has an airfoil (8). As the propeller rotates, it causes (9) to move faster in front of the blades than behind them. The air (10), then, is lower in front than in back. This difference pulls the propeller (11). The airplane is pulled forward, too. But theres more to flying than moving forward. An airplane pilot also needs to (12) the craft. For this, the plane has control surfaces. These are moveable flaps on the planes wings and tail.
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7. Find in the texts the Russian equivalents for the following words and expressions:
(1) vehicle, (2) motor, (3) power plant, (4) rotor plane, (5) airfoil, (6) tempo, (7) supersonic Mach number, (8) hypersonic velocity, (9) efficiency
8. Answer the following questions. Begin your answers with such introductory phrases as: as far as I know; as far as I remember; to my mind; certainly; it's hard to tell; probably; of course; if I am not mistaken, etc.
1) Is every aircraft an airplane? Why?
2) Why are there so many different types of airplanes?
3) What are four basic wing types?
4) What are the speed classifications?
5) What does the term Mach mean?
6) What purposes are airplanes designed for?
7) Can you compare the performances of passenger airplanes and jet fighters?
Speaking
Give a 5-minute presentation on one of the following topics. Use the Extemporaneous Method of Delivery.
1) Airplanes and aircrafts
2) Speed classification for airplanes
| Some guidelines for the effective implementation of the extemporaneous method of delivery: 1. Memorize 3 parts of an extemporaneous speech: ● the opening lines; ● the major propositions; ● the closing lines. 2. Memorize the main ideas in the order to their presentation. 3. Write the key phrases of your speech on a sheet of paper or on cards. 4. Rehearse your speech. [ : Learning to Speak in Public, 2002] |
Writing
Summarise the airplanes classifications in a short paragraph of 100 words. You can classify from from general to specific or from specific to general. Use the phrases.
| Classification from general to specific | Classification from specific to general |
| re classified into categories can be devided into types include consists of comprise | is a type of are parts/ components of constitute make up |
