Why Does It Fly?

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Wh y s e o D It Fly?

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You can find the answers to these and other questions about flight and gravity in Why Does It Fly?

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What makes flight possible?

Why can a bumblebee fly?

How does a jet engine work?

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Why s e o ~ I t D ~Fly? ~ ~ ~ ~ ~ ~ oore M b Ro

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and othe r quest i o ns about fli ght

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Why does a plane f l y?

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How does a jet engine work?

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Questions about flight. . . . . . . . . . . . . . . . . . . . . . . 4

Questions about bumblebees and kites . . . . . . . 12

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Questions about space flight . . . . . . . . . . . . . . . . 16

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It’s a fact . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Can you believe it? . . . . . . . . . . . . . . . . . . . . . . . . 22

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Who found out?. . . . . . . . . . . . . . . . . . . . . . . . . . . 26 Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 Find the answers . . . . . . . . . . . . . . . . . . . . . . . . . . 33

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~ Questions about flight ~ ~ ~Q:

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Why does a plane fly?

A: Four forces make it possible for

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a plane to fly: one to lift it up, one to pull it down, one to push it forward and one to hold it back. They are called lift, gravity, thrust and drag.

Thrust and lift are the forces that keep the plane in the air. The design of planes gives them lift and they have powerful engines to give them thrust.

To make the plane fly, these forces are stronger than their opposites, drag and gravity.

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Drag Lift

Thrust

Gravity

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Q: H ow do gliders stay up in the air?

A: Gliders do not have thrust, so they need

something to pull them into the sky to give them momentum. They have long thin wings that give them good lift, but they need ‘thermals’ to keep them in the air. Thermals are currents of air that rise because they are warmer than the air around them. A glider needs to use the lift of this warmer air to help it to go higher.

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Flying high

Birds and insects use their wings to lift them off the ground and to support their weight on currents of air. People have always wanted to fly like birds, and scientists and inventors looked for ways to make wings for hundreds of years. The Italian artist and inventor, Leonardo da Vinci, drew designs for flying machines in the early 1500s.

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Q: H ow do aircraft wings work?

A: An aircraft’s wings are large to give it lift so it

can fly. The shape of the wings makes the air on top of the wings move faster than the air below them. This makes an area of lower pressure above the wing. The air below the wing has a higher pressure, so it pushes the wing up from below, and this gives the aircraft lift. A plane that can travel very fast does not need large wings.

Fast moving air over the wing = low pressure

Slow moving air below the wing = higher pressure

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An F16 Falcon – a jet fighter

Jet fighters have smaller wings because they move through the air very quickly. Cargo aircraft are slower so they have large wings to give them lift.

A C17 Globemaster III – a cargo aircraft

An F15 Eagle – a jet fighter

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Q: H ow does a jet engine work?

A: When you blow a balloon up and

let it go, the air comes out very fast and it makes the balloon fly off in the opposite direction. A jet engine works in the same way. First it pulls air in at the front with a fan and mixes the air with fuel. An electric spark lights the mixture and the burning gases blast out of the back of the engine. This gives the plane thrust and makes it go forward.

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Q: W ho flew the first aircraft?

A: The Wright brothers flew the first successful

flying machine in 1903. It had one engine attached to the frame which turned propellers and made enough power to keep the aircraft moving forward at speed. The air going fast over the wings gave it lift to keep it in the air.

This is the 1903 Wright Flyer at the Smithsonian National Air and Space Museum in Washington, DC, USA.

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Q: H ow does a bumblebee fly?

A: Bumblebees have small, flat wings

and round, heavy bodies so people did not understand how they could fly. In fact, a bumblebee uses its wings more like a helicopter than an aeroplane.

It rotates its wings very fast, at about 200 beats a second, to get lift and flies forward by turning its wings down at the front. This turns the lift into thrust.

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Q: How do kites f ly?

A: Kites use the force of lift to fly. Lift

takes the kite up, against the force of gravity. Some kites have a tail, which gives them more stability because the tail causes drag. This holds the bottom of the kite down and keeps it steady. If you let go of the line, the kite becomes a glider with no thrust, and gravity pulls it back down to the ground.

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How does the space shuttle f ly into space?

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A: The space shuttle has rocket boosters to help it

take off vertically. Then the rocket boosters separate from the shuttle and the shuttle goes into orbit around Earth. It returns to Earth without power, like a glider. Gravity pulls it towards the ground and its wings are shaped so it can glide down. The space shuttle uses a parachute to slow down.

The space shuttle Atlantis takes off.

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A: Rockets burn fuel to make

hot gases that come out of the back of the rocket very fast.

This gives the rocket thrust and propels the spacecraft forward into space. The speed of the rocket depends on how fast the gases are propelled and how much fuel it has.

Rockets are the only engines with a power that is stronger than Earth’s gravity so they can lift objects into space.

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Atlantis uses a parachute to help it slow down.

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Superjumbo The airliner which can carry the most passengers is the Airbus A380. It can carry up to 853 passengers. It is a double-deck, wide-body, four-engine airliner and its nickname is â&#x20AC;&#x2DC;Superjumboâ&#x20AC;&#x2122;.

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Paper plane An American, Ken Blackburn, holds the world record for flying a paper aircraft for the longest time indoors with 27.6 seconds. He had ten throws and it was his tenth throw that broke the record.

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Jump jet The Harrier jump jet is a fighter plane that can take off and land vertically like a helicopter, and it can also fly horizontally like a jet.

It is like a helicopter and a jet plane in one.

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Helicopter tricks A helicopter can go forwards, backwards, up or down, or even turn around or hover. Helicopters can therefore do things that other aircraft cannot, and they are used for rescuing people, firefighting and as air ambulances.

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How helicopters fly The engine in a helicopter turns the main rotor blade on top of the helicopter. The edge of the blades is angled to force the air down as it passes over them.

This pushes the blade up and creates lift. The second rotor on the helicopter helps to steer.

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Heliflight In 1907 the French bicycle-maker Paul Cornu designed and built a powered aircraft that flew vertically.

The first flight was only very short.

The machine lifted its inventor about one third of a metre and the flight lasted about 20 seconds. The landing gear was made from four bicycle tyres because Cornu was a bicycle maker.

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Kites

The Chinese first made and used kites. In 400 BCE they used colourful kites in religious festivals. They also used them when they were at war to observe their enemies and to escape from them. Now kite flying is a popular sport.

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Parachutes

The Italian Leonardo da Vinci drew a design for a parachute during the period 1480â&#x20AC;&#x201C; 1483. It was to be made of linen and a pyramid of wooden poles. Some historians think that the Chinese made the first parachutes in the twelfth century. The first parachutes were made of silk, but now they are usually made of artificial material such as Kevlar because it is stronger and lighter than silk and does not stretch too much.

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Amazing paragliding fâ&#x20AC;&#x160;light In 2007 in Australia a storm carried a German paraglider, Ewa Wisnierska, to an altitude of over 9,000 metres (m) â&#x20AC;&#x201C; higher than the peak of Mount Everest. At about 6,000 m ice formed on her sunglasses before she lost consciousness because there was not enough oxygen. After forty minutes she became conscious again and flew her paraglider back down. She landed safely, but when rescuers found her she was still covered in ice.

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Concorde The Concorde supersonic passenger aeroplane flew from Britain and France to the USA for 27 years. It travelled at about twice the speed of sound and usually took 3 1/2 hours to cross the Atlantic â&#x20AC;&#x201C; half the normal flight time. Concorde stopped flying after one crashed in Paris in 2000.

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Flight design:

Leonardo da Vinci

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Leonardo da Vinci (1452â&#x20AC;&#x201C;1519) was born near Florence in Italy. He was a great artist and inventor who drew and designed many machines, including a tank, a submarine, a parachute and a flying machine.

He carefully studied the way the wings of birds and bats moved, and designed his flying machine so that the power came from a passenger moving his arms up and down like the wings of a bat.

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First flight:

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~ ~ ~ ~ ~ ~ ~ ~The Wright ~ Brothers ~ ~ People believe that the Wright brothers, Wilbur (1867â&#x20AC;&#x201C; 1912) and Orville (1871â&#x20AC;&#x201C;1948), were the first people to make a machine that a person could fly in. For many years they experimented with propellers and engines.

On 17 December 1903 at Kitty Hawk, North Carolina, USA, Orville flew their aircraft, the Wright Flyer, for 39 minutes. It only flew about 3 m above the ground, but it made the brothers want to continue developing their aircraft.

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Solo flight:

Amy Johnson

Amy Johnson (1903â&#x20AC;&#x201C;1941) was born in England. She became a pilot in 1928 and in 1929 she decided to be the first woman to fly solo from England to Australia. She set off on 5 May 1930, flew 13,840 kilometres, and landed in Darwin on 24 May. In 1931 Amy set a record for her flight across Siberia to Tokyo and in 1932 she broke the record for solo flight to Cape Town, South Africa. She mysteriously disappeared when she was flying over the River Thames on a cold and foggy day in January 1941, and no-one ever found her.

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Kevlar:

Stephanie Kwolek Stephanie Kwolek (1923â&#x20AC;&#x201C; ) is an American scientist who invented a new, very light material called Kevlar.

Kevlar is five times stronger than steel so it is very strong for its weight.

Lightweight materials such as Kevlar are very important in aviation. It is used for many things such as parts of planes, safety helmets and parachutes.

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altitude: height above sea level boosters: devices which increase power current: movement of water, air or electricity in a particular direction drag: the force of air that slows down a moving object gravity: the force of attraction between objects that keeps us on Earth horizontally: a direction parallel to the horizon, going across from left to right lift: an upward force that goes against the force of gravity momentum: the amount of movement in a moving object paraglider: a person who jumps into the air from a great height, attached to a fabric wing propeller: blades that spin round to drive an aircraft (or ship)

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propel: move something forward very fast stability: when something is firmly fixed, steady supersonic: able to reach a speed faster than the speed of sound thrust: the forward force of a jet or rocket engine vertically: a direction at right angles to the horizon, upright

English–Norwegian

engelsk–norsk ordliste:

airliner: rutefly altitude: høyde over havet bat: flaggermus bumblebee: humle conscious: bevisstløs current of air: luftstrøm disappear: forsvinne drag: luftmotstand engine: motor fan: vifte

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fighter plane: jagerfly firefighting: bekjempe brann foggy: tåkete force: kraft fuel: drivstoff glider: glidefly, seilfly gravity: tyngdekraft hold back: holde tilbake hover: sveve kite: drage lift up: løfte opp momentum: framdrift orbit: bane parachute: fallskjerm pull down: trekke ned push forward: dytte forover rocket: rakett space shuttle: romferje submarine: undervannsbåt thermal: oppvind thrust: drivkraft

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© CAPPELEN DAMM AS, Cambridge University Press og Denise Ryan & Associates 2011 ISBN 978-82-02-35919-5 (gjelder hele boksen med Level 8-bøker)

Materialet i denne publikasjonen er omfattet av åndsverklovens bestemmelser. Uten særskilt avtale med Cappelen Damm AS er enhver eksemplarframstilling og tilgjengeliggjøring bare tillatt i den utstrekning det er hjemlet i lov eller tillatt gjennom avtale med Kopinor, interesseorgan for rettighetshavere til åndsverk.

Utnyttelse i strid med lov eller avtale kan medføre erstatningsansvar og inndragning, og kan straffes med bøter eller fengsel.

Original konsept: Cambridge University Press og Denise Ryan & Associates 2010 Redaksjon Cambridge University Press: Jean Glasberg, Hilary Ratcliff og Claire Lawrence Redaktør Cappelen Damm AS: Toril Lindberg Tekst: Rob Moore

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1. Explain the four forces which make it possible for a plane to fly: lift, gravity, thrust and drag.

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2. Why does a cargo aircraft have bigger wings than a jet fighter?

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3. Explain the similarity between a balloon and a jet engine.

4. Explain the similarity between a bumblebee and a helicopter.

5. Why is a tail good for a kite?

6. How can rockets lift objects into space?

7. List at least three facts about helicopters.

8. What is the difference between a parachutist and a paraglider?

9. What did Leonardo da Vinci like to draw?

10. What are the Wright brothers and Amy Johnson known for?

www.cdu.no

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