I.T.S.T. TRASPORTI E LOGISTICA COSTRUZIONE DEL MEZZO AEREO

V ANNO

INGLESE

- English Articles - Prepositions Of Place - Modal Verbs - Comparative And Superlative Adjectives - Principles Of Flight - The 4 Forces Of Flight - Straight And Level - Aerofoil Characteristics - Bernoulli's Principle - Phases Of A Flight - Airplane Parts & Functions - International Air Law

ENGLISH ARTICLES

Articles in the English language are the definite article the and the indefinite articles a and an. Use of the definite article implies that the speaker assumes the listener knows the identity of the noun's referent (because it is obvious, because it is common knowledge, or because it was mentioned in the same sentence or an earlier sentence). Use of an indefinite article implies that the speaker assumes the listener does not have to be told the identity of the referent. In some noun phrases, no article is used. Use of articles The rules of English grammar require that in most cases a noun, or more generally a noun phrase, must be "completed" with a determiner to clarify what the referent of the noun phrase is. The most common determiners are the articles the and a(n), which specify the presence or absence of definiteness of the noun. Other possible determiners include words like this, my, each and many – see English determiners. There are also cases where no determiner is required, as in the sentence John likes fast cars. The definite article the is used when the referent of the noun phrase is assumed to be unique or known from the context. For example, In the sentence The boy with glasses was looking at the moon, it is assumed that in the context the reference can only be to one boy and one moon. However, the definite article is not used:

• with generic nouns (plural or uncountable): cars have accelerators, happiness is contagious, referring to cars in general and happiness in general (compare the happiness I felt yesterday, specifying particular happiness);

• with many proper names: John, France, London, etc. The indefinite article a (before a consonant sound) or an (before a vowel sound) is used only with singular, countable nouns. It indicates that the referent of the noun phrase is one unspecified member of a class. For example, the sentence An ugly man was smoking a pipe does not refer to any specifically known ugly man or pipe. When referring to a particular date, the definite article the is typically used.

• He was born on the 10th of May. •

However, when referring to a day of the week, the indefinite article 'a' is used.

• He was born on a Thursday.

No article is used with plural or uncountable nouns when the referent is indefinite (just as in the generic definite case described above). However, in such situations, the determiner some is often added (or any in negative contexts and in many questions). For example:

• There are apples in the kitchen or There are some apples in the kitchen; • We do not have information or We do not have any information; • Would you like tea? or Would you like some tea? and Would you like any

tea? or Would you like some good tea? Additionally, articles are not normally used:

• in noun phrases that contain other determiners (my house, this cat, America's history), although one can combine articles with certain other determiners, as in the many issues, such a child (see English determiners § Combinations of determiners).

• with pronouns (he, nobody), although again certain combinations are possible (as the one, the many, the few).

• preceding noun phrases consisting of a clause or infinitive phrase (what you've done is very good, to surrender is to die).

If it is required to be concise, e.g. in headlines, signs, labels, and notes, articles are often omitted along with certain other function words. For example, rather than The mayor was attacked, a newspaper headline might say just Mayor attacked. For more information on article usage, see the sections Definite article § Notes and § Indefinite article below. For more cases where no article is used, see Zero article in English. Word order In most cases, the article is the first word of its noun phrase, preceding all other adjectives and modifiers.

• The little old red bag held a very big surprise. There are a few exceptions, however:

• Certain determiners, such as all, both, half, double, precede the definite article when used in combination (all the team, both the girls, half the time, double the amount).

• The determiner such and exclamative what precede the indefinite article (such an idiot, what a day!).

• Adjectives qualified by too, so, as and how generally precede the indefinite article: too great a loss, so hard a problem, as delicious an apple as I have ever tasted, I know how pretty a girl she is.

• When adjectives are qualified by quite (particularly when it means "fairly"), the word quite (but not the adjective itself) often precedes the indefinite article: quite a long letter.

Definite article The only definite article in English is the word the, denoting person(s) or thing(s) already mentioned, under discussion, implied, or otherwise presumed familiar to the listener or reader. The is the most commonly used word in the English language, accounting for 7% of all words. "The" can be used with both singular and plural nouns, with nouns of any gender, and with nouns that start with any letter. This is different from many other languages which have different articles for different genders and/or numbers. Abbreviations for "the" and "that" Since "the" is one of the most frequently used words in English, at various times short abbreviations for it have been found:

• Barred thorn: the earliest abbreviation, it is used in manuscripts in the Old English language. It is the letter þ, with a bold horizontal stroke through the ascender, and it represents the word þæt, meaning "the" or "that" (neuter nom. / acc.)

• þ ͤand þ ͭ (þ with a superscript e or t) appear in Middle English manuscripts for "þe" and "þat" respectively.

• y ͤand y ͭ are developed from þͤ and þͭ and appear in Early Modern manuscripts and in print (see Ye form below).

Occasional proposals have been made by individuals for an abbreviation. In 1916, Legros & Grant included in their classic printers' handbook Typographical Printing-Surfaces, a proposal for a letter similar to Ħ to represent "Th", thus abbreviating "the" to ħe. Why they did not propose reintroducing to the English language "þ", for which blocks were already available for use in Icelandic texts, or the y ͤ form is unknown.

Ye form In Middle English, the (þe) was frequently abbreviated as a þ with a small e above it, similar to the abbreviation for that, which was a þ with a small t above it. During the latter Middle English and Early Modern English periods, the letter thorn (þ) in its common script, or cursive, form came to resemble a y shape. As a result, the use of a y with an eabove it as an abbreviation became common. It can still be seen in reprints of the 1611 edition of the King James Version of the Bible in places such as Romans 15:29 or in the Mayflower Compact. Historically, the article was never pronounced with a y sound even when it was so written. Indefinite article "An" redirects here. For other uses, see AN. The indefinite article of English takes the two forms a and an. Semantically, they can be regarded as meaning "one", usually without emphasis. They can be used only with singular countable nouns; for the possible use of some (or any) as an equivalent with plural and uncountable nouns, see Use of some below. Distinction between a and an The form an is used before words starting with a vowel sound, regardless of whether the word begins with a vowel letter. This avoids the glottal stop (momentary silent pause) that would otherwise be required between a and a following vowel sound. Where the next word begins with a consonant sound, a is used. Examples: a box; an apple; an SSO (pronounced "es-es-oh"); a HEPA filter (HEPA is pronounced as a word rather than as letters); an hour (the his silent); a one-armed bandit (pronounced "won..."); an heir (pronounced "air"); a unicorn (pronounced "yoo-"); an herb in American English (where the h is silent), but a herb in British English; "a unionized worker" but "an unionized particle". Some speakers and writers use an before a word beginning with the sound /h/ in an unstressed syllable: an historical novel, an hotel. When this is spoken, the "h" is not pronounced so "an hotel", for example, sounds like "an 'otel". However, this usage is now less common. Some dialects, particularly in England (such as Cockney), silence many or all initial h sounds (h-dropping), and so employ an in situations where it would not be used in the standard language, like an 'elmet (standard English: a helmet). There used to be a distinction analogous to that between a and an for the possessive determiners my and thy, which became mine and thine before a vowel, as in mine eyes.

In other languages Other more or less analogous cases in different languages include the Yiddish articles "a" ( ַא) and "an" (ַאן) (used in essentially the same manner as the English ones), the Hungarian articles a and az (used the same way, except that they are definite articles; juncture loss, as described below, has occurred in that language too), and the privative a-and an- prefixes, meaning "not" or "without", in Greek and Sanskrit. Pronunciation Both a and an are usually pronounced with a schwa: /ə/, /ən/. However, when stressed (which is rare in ordinary speech), they are normally pronounced respectively as /eɪ/ (to rhyme with day) and /æn/ (to rhyme with pan). See Weak and strong forms in English. Etymology An is the older form (related to one, cognate to German ein; etc.). Usage The principles for use of the indefinite article are given above under § Use of articles. In addition to serving as an article, a and an are also used to express a proportional relationship, such as "a dollar a day" or "$150 an ounce" or "A sweet a day helps you work, rest and play", although historically this use of "a" and "an" does not come from the same word as the articles. Juncture loss In a process called juncture loss, the n has wandered back and forth between the indefinite article and words beginning with vowels over the history of the language, where for example what was once a nuncle is now an uncle. The Oxford English Dictionary gives such examples as smot hym on the hede with a nege tool from 1448 for smote him on the head with an edge tool, as well as a nox for an ox and a napple for an apple. Sometimes the change has been permanent. For example, a newt was once an ewt (earlier euft and eft), a nickname was once an eke-name, where eke means "extra" (as in eke out meaning "add to"), and in the other direction, a napron (meaning a little tablecloth, related to the word napkin) became an

apron, and a naddre became an adder. The initial n in orange was also dropped through juncture loss, but this happened before the word was borrowed into English. Use of some The existential determinative (or determiner) some is sometimes used as a functional equivalent of a(n) with plural and uncountable nouns (also called a partitive). For example, Give me some apples, Give me some water (equivalent to the singular countable forms an apple and a glass of water). Grammatically this some is not required; it is also possible to use zero article: Give me apples, Give me water. The use of some in such cases implies a more limited quantity. (Compare the forms unos/unas in Spanish, which are the plural of the indefinite article un/una.) Like the articles, some belongs to the class of "central determiners", which are mutually exclusive (so "the some boys" is ungrammatical). The contrasting use of any in negative clauses proves that some is polarity-sensitive, and occurs in positive clauses: "I have some objections to make", vs. "I don't have any objections to make; "I have any objections to make" and "I don't have some objections to make" are ungrammatical. Some can also have a more emphatic meaning: "some but not others" or "some but not many". For example, some people like football, while others prefer rugby, or I've got some money, but not enough to lend you any. It can also be used as an indefinite pronoun, not qualifying a noun at all (Give me some!) or followed by a prepositional phrase (I want some of your vodka); the same applies to any. Some can also be used with singular countable nouns, as in There is some person on the porch, which implies that the identity of the person is unknown to the speaker (which is not necessarily the case when a(n) is used). This usage is fairly informal, although singular countable some can also be found in formal contexts: We seek some value of x such that... When some is used just as an indefinite article, it is normally pronounced weakly, as [s(ə)m]. In other meanings, it is pronounced [sʌm]. Effect on alphabetical order In sorting titles and phrases alphabetically, articles are usually excluded from consideration, since being so common makes them more of a hindrance than a help in finding a desired item. For example, The Comedy of Errors is alphabetized before A Midsummer Night's Dream, because the and a are ignored and comedy alphabetizes before midsummer. In an index, the former work might be written "Comedy of Errors, The", with the article moved to the end.

PREPOSITIONS OF PLACE

In front of

• A band plays their music in front of an audience. • The teacher stands in front of the students. • The man standing in the line in front of me smells bad. • Teenagers normally squeeze their zits in front of a mirror.

Behind Behind is the opposite of In front of. It means at the back (part) of something.

• When the teacher writes on the whiteboard, the students are behind him (or her).

• Who is that person behind the mask? • I slowly down because there was a police car behind me.

Between Between normally refers to something in the middle of two objects or things (or places).

• There are mountains between Chile and Argentina. • The number 5 is between the number 4 and 6. • There is a sea (The English Channel) between England and France.

Across From / Opposite Across from and Opposite mean the same thing. It usually refers to something being in front of something else BUT there is normally something between them like a street or table. It is similar to saying that someone (or a place) is on the other side of something.

• I live across from a supermarket (= it is on the other side of the road) • The chess players sat opposite each other before they began their game.

(= They are in front of each other and there is a table between them)

Next to / Beside Next to and Beside mean the same thing. It usually refers to a thing (or person) that is at the side of another thing.

• At a wedding, the bride stands next to the groom. • Guards stand next to the entrance of the bank. • He walked beside me as we went down the street. • In this part of town there isn't a footpath beside the road so you have to be

careful.

Near / Close to Near and Close to mean the same thing. It is similar to next to / beside but there is more of a distance between the two things.

• The receptionist is near the front door. • This building is near a subway station. • We couldn't park the car close to the store. • Our house is close to a supermarket.

On On means that something is in a position that is physically touching, covering or attached to something.

• The clock on the wall is slow. • He put the food on the table. • I can see a spider on the ceiling. • We were told not to walk on the grass.

Above / Over Above and Over have a similar meaning. The both mean "at a higher position than X" but above normally refers to being directly (vertically) above you.

• Planes normally fly above the clouds.

• There is a ceiling above you. • There is a halo over my head. ;) • We put a sun umbrella over the table so we wouldn't get so hot. • Our neighbors in the apartment above us are rally noisy.

Over can also mean: physically covering the surface of something and is often used with the word All as in All over.

• There water all over the floor. • I accidentally spilled red wine all over the new carpet.

Over is often used as a Preposition of Movement too.

Under / Below Under and Below have a similar meaning. They mean at a lower level. (Something is above it).

• Your legs are under the table. • Monsters live under your bed. • A river flows under a bridge. • How long can you stay under the water? • Miners work below the surface of the Earth.

Sometimes we use the word underneath instead of under and beneath instead of below. There is no difference in meaning those they are less common nowadays.

Under is often used as a Preposition of Movement too.

MODAL VERBS

Here's a list of the modal verbs in English:

Modals are different from normal verbs: 1: They don't use an 's' for the third person singular. 2: They make questions by inversion ('she can go' becomes 'can she go?'). 3: They are followed directly by the infinitive of another verb (without 'to'). Probability First, they can be used when we want to say how sure we are that something happened / is happening / will happen. We often call these 'modals of deduction' or 'speculation' or 'certainty' or 'probability'. For example:

• It's snowing, so it must be very cold outside. • I don't know where John is. He could have missed the train. • This bill can't be right. £200 for two cups of coffee!

Ability We use 'can' and 'could' to talk about a skill or ability. For example:

• She can speak six languages. • My grandfather could play golf very well. • I can't drive.

Obligation and Advice We can use verbs such as 'must' or 'should' to say when something is necessary or unnecessary, or to give advice. For example:

• Children must do their homework. • We have to wear a uniform at work. • You should stop smoking.

Permission We can use verbs such as 'can', 'could' and 'may' to ask for and give permission. We also use modal verbs to say something is not allowed. For example:

• Could I leave early today, please? • You may not use the car tonight. • Can we swim in the lake?

Habits We can use 'will' and 'would' to talk about habits or things we usually do, or did in the past. For example: When I lived in Italy, we would often eat in the restaurant next to my flat. John will always be late!

COMPARATIVE AND SUPERLATIVE ADJECTIVES

Adjectives can compare two things or more than two things. When we make these comparisons, we use comparative and superlative forms of adjectives. Comparatives One way to describe nouns (people, objects, animals, etc.) is by comparing them to something else. When comparing two things, you’re likely to use adjectives like smaller, bigger, taller, more interesting, and less expensive. Notice the �er ending, and the words more and less. A mistake that both native speakers and non-native speakers make is using incorrectly formed comparative adjectives. See the sentences below for an illustration of this common error: Incorrect: His cat is more large than my dog. Correct: His cat is larger than my dog. So what makes the first example wrong and the second right? There are a few rules that explain this:

• For adjectives that are just one syllable, add -er to the end (this explains the above example).

• For two-syllable adjectives not ending in -y and for all three-or-more-syllable adjectives, use the form “more + adjective.”

• For two-syllable adjectives ending in -y, change the -y to -i and add -er.

These simple rules make it easy to tell when you should add -er or -ier and when you should use “more + adjective.” Here are a few more examples: Correct: This house is more exciting than ever. Incorrect: This house is excitinger than ever. Correct: Mike is funnier than Isaac. Incorrect: Mike is more funny than Isaac. Notice the spelling change for adjectives ending in �y: the comparative ends in �ier. Incorrect: This book is boringer than the last one. Correct: This book is more boring than the last one.

Incorrect: Advertising pressures women to be more thin . Correct: Advertising pressures women to be thinner . Superlatives When comparing more than two things, you’ll likely use words and phrases like smallest, biggest, tallest, most interesting, and least interesting. Notice the �est ending and the words most and least. Make sure you use the proper ending or superlative adjective when forming these superlatives. The examples below illustrate the correct form: Incorrect: Martha is the elder of the four sisters. If there were only two sisters, we could use the comparative elder here. Because there are four sisters, we need a superlative. Correct: Martha is the eldest of the four sisters. Here are a couple of other examples: Correct: I think his last book is his least interesting ; his third book was the most interesting . Correct: That must be the weirdest play ever written. Remember that adjectives ending in �y change their spelling when �est is added. To form these superlatives, change the y to an i before adding the -est ending, as illustrated below: Incorrect: That is the sleepyest puppy of the litter. Correct: That is the sleepiest puppy of the litter. Forming Comparative and Superlatives of Irregular Adjectives It’s important to note that there are irregular adjectives (and adverbs) that you have to memorize because they don’t follow the rules above. They are:

Here are some examples of these irregular words as comparatives and superlatives in context: Correct: Today I had the best time touring the city. Correct: I went farther than my friend when we walked around the park. Correct: You dance better than I do. Correct: You bought the least attractive pair of moccasins at the thrift store. Correct: He can run the farthest of his classmates, but that’s only once around the track. Correct: I do badly in math, but at least I’m not the worst . Comparative and Superlative of “Handsome” Besides the irregular words in the table above, one other unclear comparative/superlative choice is handsomer/more handsome and handsomest/most handsome. The rules call for handsomer and handsomest, but usage has changed over time. Modern speakers prefer more handsome to handsomer, and there is an even split between handsomest and most handsome. Preferred usage typically follows what native speakers say, and the trend seems to be moving toward the simpler construction of more + adjective and the most + adjective.

PRINCIPLES OF FLIGHT

For thousands of years, people have wanted to fly. Our legends and fairy tales are full of humans and animals that can fly – effortlessly gliding through the air. In real life, of course, no one can just fly into the air. We don’t have wings and a power source strong enough to keep the wings moving through the air to sustain the lift necessary for flight.

Taking wing Planes and birds are both affected by the same forces in flight. They have to be able to provide enough lift force to oppose the weight force. Our attempts to fly have taken us from flimsy paper hot-air balloons and strange-looking gliders to supersonic jet planes. We have learned about the forces of flight, and we know what it takes to keep birds and planes in the air. Force can be defined as a push or pull. Unbalanced forces produce an acceleration of an object in the direction of the resultant force. Four main forces affect the flight abilities of birds and planes – weight, lift, thrust and drag. Weight and lift We all know that gravity is a force that pulls everything towards the Earth’s surface. This pull is called the weight force. Planes and birds have to be able to provide enough lift force to oppose the weight force. Lift is a force that acts upwards against weight and is caused by the air moving over and under the wings. Thrust and drag The power source of a bird or plane provides the thrust. Thrust is the force that moves the object forward. Thrust is provided by: muscles – for birds and other flying animals engines – for flying machines

gravity – for gliders that actually fly by always diving at a very shallow angle (birds do this too when they glide). The force working against thrust is called drag. It is caused by air resistance and acts in the opposite direction to the motion. The amount of drag depends on the shape of the object, the density of the air and the speed of the object. Thrust can overcome or counteract the force of drag.

Forces affecting flight Four main forces affect the flight abilities of birds and planes. These forces are weight, lift, drag and thrust. How it works An object in flight is constantly engaging in a tug of war between the opposing forces of lift, weight (gravity), thrust and drag. Flight depends on these forces – whether the lift force is greater than the weight force and whether thrust is greater than drag (friction) forces. Lift and drag are considered aerodynamic forces because they exist due to the movement of an object (such as a plane) through the air. The weight pulls down on the plane opposing the lift created by air flowing over the wing. Thrust is generated by the propeller (engine) and opposes drag caused by air resistance. During take-off, thrust must counteract drag and lift must counteract the weight before the plane can become airborne. If a plane or bird flies straight at a constant speed

• lift force upwards = weight force downwards (so the plane/bird stays at a constant height)

• thrust force forwards = opposing force of drag (so the plane/bird stays at a constant speed).

If the forces are not equal or balanced, the object will speed up, slow down or change direction towards the greatest force. For example, if a plane’s engine produces more thrust, it will accelerate. The acceleration increases air speed past the wing, which increases lift so the plane gains altitude. Then, because the plane is moving faster, drag (air resistance) is increased, which slows the plane from speeding up as quickly until thrust and drag are equal again. The plane can now remain at a constant but greater height. A plane can lose altitude by reducing thrust. Drag becomes greater than thrust and the plane slows down. This reduces lift and the plane descends.

THE 4 FORCES OF FLIGHT

In level flight, lift equals weight and thrust equals drag when the plane flies at constant velocity.

Maintaining a steady flight requires a balance, often described as an equilibrium of all the forces acting upon an airplane. Weight, lift, thrust and drag are the acting forces on an airplane. Assuming a straight and level flight, lift must be equal to weight and drag must be equal to thrust. This is what happens if this equilibrium is violated:

• If lift becomes greater than weight, then the plane will accelerate upward.

• If the weight is greater than the lift, then the plane will accelerate downward.

• When the thrust becomes greater than the drag, the plane will accelerate forward.

• If drag becomes greater than the thrust a deceleration will occur.

• Acceleration is best explained by using Newton's Second Law of Motion.

The proportion between weight and thrust is determined by the airplane designer depending on the anticipated missions. For example, if by design an airplane must be able to accelerate vertically upwards then the thrust must be greater than the weight and drag combined. In small aircraft the weight/thrust ratio is about. 10:1. Thrust opposes drag. The engine creates thrust and moves the plane forward. (Gravity provides the thrust for a glider.) The engines push air back with the same force that the air moves the plane forward; this thrust force-pair is always equal and opposite

according to Newton's 3rd Law. When thrust is greater than drag, the plane accelerates according to Newton's 2nd Law. When the plane flies level at constant velocity, thrust equals drag. When the plane flies level at constant velocity, all opposite forces of flight are equal: drag = thrust and weight = lift. How the 4 forces of flight interact

Drag opposes thrust. Imagine sticking your hand out the window of a moving car and flying your hand. The force that pushes your hand back is called "drag". As your hand pushes on the wind, the wind also pushes against your hand. Isaac Newton would say that force of your hand pushing on the air is always equal to the force of the air pushing on your hand; this is his third law. When the plane flies level at constant velocity, weight = lift! When the engines of a plane quit, drag slows the plane down according to Newton's 2nd Law. How the 4 forces of flight interact Legs of birds and wheels of planes are tucked in to reduce drag. Drag is unwanted because it makes the plane or bird inefficient. Planes with more drag require more thrust to fly successfully. To reduce drag and increase efficiency, planes are streamlined. Planes also use camber and high aspect ratios to reduce drag. Lift opposes weight. Newton's Laws and Bernoulli's Principle generate lift. A plane that sits on a runway doesn't have any lift, but it does have weight. Lift is proportional to the square of the velocity of an airplane and as a plane goes faster, its lift increases. As a plane moves forward, its lift force increases until it equals its weight. When lift equals weight, the plane can fly. In level flight, lift equals weight as the plane flies at constant velocity.

When a plane accelerates upward, lift is greater than weight. In contrast, lift = weight when the plane flies level at constant speed. Imagine sticking your hand out the window of a moving car and flying your hand. As you tilt your hand up slightly, lift is the force that pushes your hand up. (Actually, lift is perpendicular to the direction of movement.) Lift is equal to the weight as your hand flies level at constant velocity. When a plane stalls, lift is lost! Stalling can occur due to insufficient air velocity or an excessive angle of attack. Weight opposes lift. Weight and lift are equal when a plane flies level at constant velocity. Because excess weight requires more lift, and therefore more thrust, heavy planes are more difficult to get off the ground as compared to lighter planes. Planes with less weight require less thrust. Thus, planes are designed to be as light as possible. The opposite forces of flight are equal only when a plane flies level at constant velocity

The opposite forces of flight are not always equal. For instance, as a plane climbs, its weight is equal to a portion of the lift force and a portion of the thrust force. In this situation, the opposite forces of flight are no longer equal to one another. However, according to Newton's 3rd Law, the force of air pushing on the plane is still equal to the force of the plane pushing through the air.

STRAIGHT AND LEVEL

We must be able to fly the aeroplane in a straight line, on a constant heading and at a constant altitude. Maintaining a constant altitude requires a constant attitude and a constant heading requires the aeroplane to be wings level and in balance.

This is the first exercise in coordination for the student, and it is very important that they understand, and can then demonstrate, how the controls they learnt about in the previous Effect of Controls lesson are used to achieve and maintain a constant heading, constant altitude, constant airspeed, and in balance.

It is also an important lesson because it shows the interrelation of a number of variables, such as power, airspeed, pitch and yaw.

The lesson should initially cover configuring straight and level flight at a constant airspeed and then maintaining it. It is followed by regaining straight and level after a disturbance and finally straight and level at different airspeeds and power settings.

It is critical that the student understands that straight and level is achieved by referencing the aeroplane’s attitude with the horizon, and then checked by reference to the aeroplane’s instruments. Use a moveable ‘windscreen view’ to show the correct attitude for straight and level flight.

Objectives

To establish and maintain straight and level flight, at a constant airspeed, constant altitude, in a constant direction, and in balance.

To regain straight and level flight.

To maintain straight and level flight at selected airspeeds or power settings.

Principles of Flight

In VFR flight, flying straight and level should only be accomplished with reference to the horizon. Define the horizon for the student and explain how the horizon can be identified if it is not visible, for example with hills or weather in the way.

The Four Forces

The four forces acting on the aeroplane should be explained.

Weight

Acts straight down through the centre of gravity.

Lift

Is produced by the wings and acts upwards through the centre of pressure.

Thrust

Is provided by the engine through the propeller.

Drag

Is the resistance to motion felt by all bodies within the atmosphere.

Equilibrium requires a constant airspeed and constant direction (the combination of these is velocity). A constant direction is maintained by the wings being level and the aeroplane in balance. Equilibrium is achieved when lift = weight and thrust = drag.

Describe how the arrangement of these forces forms couples. Lift acts through its centre of pressure and is slightly behind the centre of gravity, where weight acts (small moment arm), creating a nose-down pitching couple. The comparative size of the lift and weight forces to thrust and drag forces should be discussed. For general aviation aeroplanes the lift/drag ratio is said to be about 10:1. Your diagram should reflect this ratio approximately – a picture is worth a thousand words.

The ideal arrangement is for the thrust line to be well below the drag line. This provides a large moment arm to compensate for the smaller forces of thrust and drag, and creates a nose-up couple that balances the nose-down couple of lift and weight.

In the previous lesson Effect of Controls, the student saw the pitch change when power was increased and decreased. The arrangement of these couples is the reason for the pitch changes. A decrease in power will pitch the nose down into a descent, without pilot input, and an increase in power will pitch the nose up.

In practice, getting the thrust and drag lines separated far enough to balance the lift/weight couple is not possible. Therefore, the tailplane is set at an angle of attack that will provide a down force on the tailplane in level flight, which combined with the large moment arm, balances the forces.

Any further imbalance between the couples, as a result of weight or airspeed changes for example, are compensated for by the elevator.

Lift

Lift is generated by air flowing faster over the top surface of the wing, compared with air flowing under the wing. Air is made to flow faster by shaping the top surface – called camber.

The formula for lift is:

L = CL ½ ρ V2 S

Where,

CL is the co-efficient of lift (angle of attack)

½ is a constant

ρ (rho) is the density of the air

V is the airspeed, and

S is the surface area of the wing.

The two elements the pilot can easily control are airspeed and angle of attack, so in essence;

L = angle of attack x airspeed

Angle of attack (α) is the angle between the relative airflow and the chordline of the aeroplane’s wing.

The most efficient angle of attack is approximately 4 degrees, but as no angle-of-attack indicator is fitted to light aeroplanes, the airspeed is used as a guide to the aeroplane’s angle of attack.

In order to keep lift constant, any change in the angle of attack must be matched by a change in the airspeed. For example if airspeed increases, less angle of attack is required to maintain a constant lift. A decrease in airspeed will require an increase in the angle of attack to maintain constant lift and consequently altitude.

Performance

Introduce the concept of

Power + Attitude = Performance

Power is set by reference to rpm – use the organisation’s recommended rpm setting for training flights, in the example below we have used 2200 rpm.

The attitude will depend on the aeroplane type, in this example we will use four fingers below the horizon.

In this case the performance we want is a constant altitude, direction and airspeed – straight and level.

Power + Attitude = Performance

(2200) (four fingers) (straight and level)

Airmanship

Discuss the lateral boundaries of the training area and the importance of managing the flight to remain within them.

Revise ‘I have control – you have control.’

Aeroplane Management

Stress the importance of smooth but positive control movements.

Operation of the mixture control has been explained in the previous lesson. During initial training, as a result of regular altitude and power changes, the mixture is normally left in the full rich position.

Revise why carburettor heat is set to HOT at power settings below (commonly the green arc or 1900–2000 rpm).

Human Factors

Review the visual limitations discussed in the last lesson and how blind spots effect a good lookout.

There is a lot of information for the student to absorb in the early lessons, so reassure the student that there will be plenty of time to master these skills.

Air Exercise

Identify the horizon, and what attitude is required relative to the horizon, with the appropriate power setting, to establish and maintain straight and level flight.

Power + Attitude = Performance

(2200) (four fingers) (straight and level)

With the use of the ‘windscreen view’ show the attitude in the correct position as well as in the too low and too high positions.

Establish Straight and Level

Establishing straight and level flight is achieved by using the mnemonic PAT.

P Power

Set the power for selected (normal) straight and level performance.

A Attitude

The attitude for straight and level is made up of three elements.

Elevator Set the nose attitude – for level (eg, four fingers)

Aileron Wings are level relative to the horizon – for straight

Rudder In balance – for straight

If a constant direction is not being maintained on the reference point (and the DI should confirm this) either the wings are not level, or the aeroplane is out of balance, or both.

Balance is confirmed with the balance ball indicator. The method used to achieve balance is ‘stand on the ball’. If the ball is out to the left, increased pressure on the left rudder pedal is required. This is a pressure increase, more than a movement and ‘stand’ implies continued pressure. Once the ball has been centred, reducing pressure will allow it to move out again.

The aeroplane is kept in balance to not only keep the aeroplane flying straight, but also for best efficiency by keeping the drag to a minimum and achieving the best airspeed.

If the correct level attitude has been selected the airspeed will be about knots. If the correct power setting is maintained the aeroplane will maintain altitude, and if the wings are level and balance maintained the aeroplane cannot turn. Therefore, the objective to fly at a constant airspeed, constant altitude, constant direction, and in balance is achieved.

T Trim

Take the time to teach this thoroughly, make sure the student relieves all of the control pressures so that their hands can come off the controls and the aeroplane remains level.

Maintaining Straight and Level

Maintaining straight and level is achieved by using the mnemonic LAI.

L Lookout

In a scan loop ahead, look out to the left and scan 20 degrees for 2 seconds from left to right, passing over the nose of the aeroplane.

A Attitude

Ensure the attitude is correct relative to the horizon and, more importantly, constant.

I Instruments

Used to confirm accurate flight – not set it. From right to left the instruments are scanned, and this brings the scan back to the left side of the aeroplane and the process starts again.

During the instrument scan, only those instruments important to the phase of flight are read. In this case the altimeter will probably be scanned on every sweep, with oil pressure and temperature scanned every 10th sweep.

Regaining Straight and Level

1. Check the airspeed, and the power setting – set the correct power setting. If the airspeed is decreasing, increase power, if the airspeed is increasing, decrease power.

2. Check the nose attitude – set the attitude for straight and level 3. Check the wings are level and the ball is in the middle – level the wings, centre

the ball 4. Reset the power after making any changes to the attitude 5. Check PAT (power, attitude, trim)

For small altitude adjustments of less than 150 feet, the attitude is altered with elevator, and when the desired altitude is regained the correct level attitude is set, held and trimmed. For bigger altitude adjustments power is usually altered.

Straight and Level at Different Airspeeds and Power Settings

Power + Attitude = Performance

It should be emphasised that every time power or airspeed is altered, a change in rudder pressure will be required to maintain balance. Therefore, during those phases of flight where power or airspeed are changing, rudder will need to be applied to maintain balance. In addition, when rudder is being used to centre the ball, the wings must be held laterally level with aileron.

List the various power, airspeed and attitude required to maintain straight and level flight. An example is shown below.

Power 2200 1800 2500

Airspeed 80–90 knots 60 knots 110 knots

Attitude Normal High Low

As can be seen, a high power setting means a higher airspeed, requiring a lower nose attitude. Conversely a low power setting means a low airspeed, requiring a higher nose attitude.

Airborne Sequence On the Ground

Show the student the preflight inspection again, and have them follow you through, pointing out what they would be looking for.

• Make sure the student’s seat is properly adjusted. • Talk the student through the engine start up. • Revise taxiing. • Talk the student through the checks.

The Exercise

Have the student follow you through with the takeoff, and once safely airborne hand over control to the student, showing them the climb attitude and reference point you want them to hold.

On the way out to the training area teach the horizon concepts and point out the local landmarks.

Establish the aeroplane in straight and level.

Point out the horizon to the student – let them note the attitude when level. Demonstrate an attitude that is too high and an attitude that is too low.

Configure the aeroplane, using PAT, in straight and level flight at normal cruising power. Once the student has recognised the attitude, and noted that the wings are level and the aeroplane is in balance, hand over control.

Talk the student through establishing straight and level using PAT and maintaining straight and level using LAI.

Make minor deviations away from straight and level and talk them through regaining it.

Show the student the effect of a marked imbalance. They should be able to ‘feel’ that the aeroplane is out of balance. Then show a slight imbalance. This is much harder for them to ‘feel’ or detect, and that is why the balance ball is used to correct slight imbalances. Show them how to correct for an imbalance.

You should then give the student some practise at regaining straight and level by disturbing the aeroplane in roll, pitch, trim and power.

Demonstrate the lookout technique, outside and inside.

Once the student is comfortable with regaining straight and level, demonstrate the different power settings, and corresponding airspeed and attitudes, required for straight and level flight. Finish by letting them practise returning to straight and level flight by changing the power, adjusting the attitude and remaining in balance.

On the return to the aerodrome, point out the local landmarks again, and show them the descending attitude, ready for the next lesson.

AEROFOIL CHARACTERISTICS

As the amount of lift varies with the angle of attack, so too does the drag. Hence drag is the price we pay for lift. Thus, although it is desirable to obtain as much lift as possible from a wing, this cannot be done without increasing the drag. It is therefore necessary to find the best compromise. The lift and drag of an airfoil depend not only on the angle of attack, but also upon: The shape of the airfoil The plan area of the airfoil (or wing area)—S. The square of the velocity (or true airspeed)—V2. The density of the air-p Hence the lift (L) and drag (D) of an airfoil can be expressed as follows:-

The symbols CL and CD represent the lift coefficient and drag coefficient respectively. They depend on the shape of the airfoil and will alter with changes in the angle of attack and other wing appurtenances. The lift-drag ratio is used to express the relation between lift and drag and is obtained by dividing the lift coefficient by the drag coefficient, CL / CD. The characteristics of any particular airfoil section can conveniently be represented by graphs showing the amount of lift and drag obtained at various angles of attack, the lift-drag ratio, and the movement of the center of pressure. Notice that the lift curve (CL-yellow curve) reaches its maximum for this particular wing section at 18 degrees angle of attack, and then rapidly decreases. 18 degrees angle of attack is therefore the stalling angle.

The drag curve (CD-blue curve) increases very rapidly from 14 degrees angle of attack and completely overcomes the lift curve at 22 degrees angle of attack. The lift-drag ratio (L/D-green curve) reaches its maximum at 0 degrees angle of attack, meaning that at this angle we obtain the most lift for the least amount of drag. The Center of Pressure(CP-red cross) moves gradually forward until 12 degrees angle of attack is reached, and from 18 degrees commences to move back. The graphs shown above represent data for one airfoil or wing cross-section. Different airfoils with different camber and airfoil thickness produce different looking curves. These curves are obtained normally by experimental work using wind tunnel tests. Many tests were run by the NACA, the predecessor to the NASA, and a booklet, NACA Report 824 (1945) was created to give the relation of coefficient of lift, coefficient of drag, pressure and moment coefficients (not shown above) for many different types of airfoil. We find that the coefficients of lift, drag and moment depend upon the angle of attack, the mach number and the Reynolds number. For subsonic speeds, normal airfoils have a linear relationship between angle of attack and coefficient of lift until just before stall occurs (the airfoil or wing experiences a loss of lift). For higher speeds, when the mach number is higher than 0.3 (mach number is the velocity of the aircraft divided by the velocity of the sound), then the coefficient of lift is

CL = CLo / (1 – M2)1/2 where CLo= the coefficient of lift at low speed M = the mach number in the free stream This correction for the mach number effect is based on Glauert who proposed it in 1928. Von Karman and Tsien proposed a more complicated equation (not shown here). Note that the coefficient of lift at low speed, CLo, is the value that is normally obtained experimentally. The above equation holds true even for mach number values less than 0.3, but the effect on the coefficient of lift is minimal. Finally, we said that the lift coefficient is also dependent on Reynolds number, RN, where RN = rVd/m Here, the Greek letter, r, represents the density of the fluid–air; V is the velocity of the free-stream airflow; d is the characteristic length of the airfoil and, the

denominator, given by the Greek symbol, m, represents the fluid viscosity. Actually, the Reynolds number determines the type of flow (whether laminar or turbulent), which, in turn, determines where the flow separates from the airfoil or wing. This, in turn, affects the lift, drag and moment coefficients, as explained above. We note that as Reynolds number increases, the maximum lift coefficient increases. But this does not occur indefinitely; when flows become very turbulent, the maximum lift coefficient begins to drop and so does the overall lift coefficient

BERNOULLI'S PRINCIPLE

This is an important principle involving the movement of a fluid through a pressure difference. Suppose a fluid is moving in a horizontal direction and encounters a pressure difference. This pressure difference will result in a net force, which by Newton's 2nd law will cause an acceleration of the fluid. The fundamental relation,

in this situation can be written as

which furthermore can be expressed as

In other words,

which is known as Bernoulli's principle. This is very similar to the statement we encountered before for a freely falling object, where the gravitational potential energy plus the kinetic energy was constant (i. e., was conserved). Bernoulli's principle thus says that a rise (fall) in pressure in a flowing fluid must always be accompanied by a decrease (increase) in the speed, and conversely, if an increase (decrease) in , the speed of the fluid results in a decrease (increase) in the pressure. This is at the heart of a number of everyday phenomena. As a very trivial example, Bernouilli's principle is responsible for the fact that a shower curtain gets ``sucked inwards'' when the water is first turned on. What happens is that the increased water/air velocity inside the curtain (relative to the still air on the other side) causes a pressure drop. The pressure difference between the outside and inside causes a net force on the shower curtain which sucks it inward. A more useful example is provided by the functioning of a perfume bottle: squeezing the bulb over the fluid creates a low pressure area due to the higher speed of the air, which subsequently draws the fluid up. This is illustrated in the following figure.

Figure 7.2: Action of a spray atomizer

Bernouilli's principle also tells us why windows tend to explode, rather than implode in hurricanes: the very high speed of the air just outside the window causes the pressure just outside to be much less than the pressure inside, where the air is still. The difference in force pushes the windows outward, and hence explode. If you know that a hurricane is coming it is therefore better to open as many windows as possible, to equalize the pressure inside and out. Another example of Bernoulli's principle at work is in the lift of aircraft wings and the motion of ``curve balls'' in baseball. In both cases the design is such as to create a speed differential of the flowing air past the object on the top and the bottom - for aircraft wings this comes from the movement of the flaps, and for the baseball it is the presence of ridges. Such a speed differential leads to a pressure difference between the top and bottom of the object, resulting in a net force being exerted, either upwards or downwards. This is illustrated in the following figure.

Figure 7.3: Lift of an aircraft wing

PHASES OF A FLIGHT

Taxiing refers to the movement of an aircraft on the ground, under its own power. The aircraft moves on wheels. An airplane uses taxiways to taxi from one place on an airport to another; for example, when moving from a terminal to the runway. The aircrafts always moves on the ground following the yellow lines, to avoid any collision with the surrounding buildings, vehicles or other aircrafts. The taxiing motion has a speed limit. Before making a turn, the pilot reduces the speed further to prevent tire skids. Just like cars, there is a certain list of priorities during taxiing. The aircrafts that are landing or taking off have higher priority. The other aircrafts have to wait for these aircrafts before they start or continue taxiing. The thrust to propel the aircraft forward comes from its propellers or jet engines. Steering is achieved by turning a nose wheel or tail wheel/rudder; the pilot controlling the direction travelled with their feet. The use of engine thrust near terminals is restricted due to the possibility of jet blast damage. This is why the aircrafts are pushed back from the buildings by a vehicle before they can start their own engines for taxiing. Take-Off Takeoff is the phase of flight in which an aircraft goes through a transition from moving along the ground (taxiing) to flying in the air, usually starting on a runway. Usually the engines are run at full power during takeoff. Following the taxi motion, the aircraft stops at the starting line of the runway. Before takeoff, the engines, particularly piston engines, are routinely run up at high power to check for engine-related problems. This makes a consid- erable noise. When the pilot releases the

brakes, the aircraft starts accelerating rapidly until the necessary speed for take-off is achieved. The takeoff speed required varies with air den- sity, aircraft weight, and aircraft configuration (flap and/or slat position, as applicable). Air density is affected by factors such as field ele- vation and air temperature. Operations with transport category aircraft employ the concept of the takeoff V-Speeds, V1 and V2. These speeds are determined not only by the above factors affecting takeoff perform- ance, but also by the length and slope of the runway. Below V1, in case of critical failures, the takeoff should be aborted; above V1 the pilot continues the takeoff and returns for land- ing. After the co-pilot calls V1, Then, V2 (the safe takeoff speed) is called. This speed must be maintained after an engine failure to meet per- formance targets for rate of climb and angle of climb. The speeds needed for takeoff are relative to the motion of the air (indicated airspeed). A head wind will reduce the ground speed needed for takeoff, as there is a greater flow of air over the wings. This is why the aircrafts always take off against the wind. Side wind is not preferred as it would disturb the stability of the aircraft. Typical takeoff air speeds for jetliners are in the 130–155 knot range (150–180 mph, 240–285 km/h). For a given aircraft, the takeoff speed is usually directly proportional to the aircraft weight; the heavier the weight, the greater the speed needed. Some aircraft have difficulty generating enough lift at the low speeds encountered during takeoff. These are therefore fitted with high-lift devices, often including slats and usually flaps, which increase the camber of the wing, making it more effective at low speed, thus creating more lift. These have to be deployed from the wing before performing any maneuver. At the beginning of the climb phase, the wheels are retracted into the aircraft and the undercarriage doors are closed. This operation is audible by the passengers as a noise coming from below the floor. Climb Following take-off, the aircraft has to climb to a certain altitude (typically 30,000 ft or 10 km) before it can cruise at this altitude in a safe and economic way. A climb is carried out by increasing the lift of wings supporting the aircraft until their lifting force exceeds the weight of the aircraft. Once this occurs, the aircraft will climb to a higher altitude until the lifting force and weight are again in balance. The increase in lift may be accomplished by increasing the angle of attack of the wings, by increasing the thrust of the engines to increase speed (thereby increasing lift), by increasing the surface area or shape of the wing to produce greater lift, or by some combination of

these techniques. In most cases, engine thrust and angle of attack are simultaneously increased to produce a climb. Because lift diminishes with decreasing air density, a climb, once initiated, will end by itself when the diminishing lift with increasing altitude drops to a point that equals the weight of the aircraft. At that point, the aircraft will return to level flight at a constant altitude. During climb phase, it is normal that the engine noise diminishes. This is because the engines are operated at a lower power level after the take-off. It is also possible to hear a whirring noise or a change in the tone of the noise during climb. This is the sound of the flaps that are retracting. A wing with retracted flap produces less noise. Cruise Cruise is the level portion of aircraft travel where flight is most fuel efficient. It occurs between ascent and descent phases and is usually the majority of a journey. Technically, cruising consists of heading (direction of flight) changes only at a constant airspeed and altitude. It ends as the aircraft approaches the destination where the descent phase of flight commences in preparation for landing. For most commercial passenger aircraft, the cruise phase of flight consumes the majority of fuel. As this lightens the aircraft considerably, higher altitudes are more efficient for additional fuel economy. However, for operational and air traffic control reasons it is necessary to stay at the cleared flight level. Typical cruising speed for long-distance commercial passenger flights is 475-500 knots (878-926 km/h; 547-578 mph). Commercial or passenger aircraft are usually designed for optimum performance at their cruise speed. There is also an optimum cruise altitude for a particular aircraft type and conditions including payload weight, center of gravity, air temperature, humidity, and speed. This altitude is usually where the drag is minimum and the lift is maximum. As in any phase of the flight, the aircraft in cruise mode is always in communication with an Air Traffic Control (ATC) station. Although the general tendency is to follow a straight line towards the destination, there may be some deviations from the flight plan for weather, turbulence or air traffic rea- sons, after receiving clearance from ATC. Descent A descent during air travel is any portion where an aircraft decreases altitude. Descents are an essential component of an approach to landing. Other partial descents

might be to avoid traffic, poor flight conditions (turbulence or bad weather), clouds (particularly under visual flight rules), to see something lower, to enter warmer air (in the case of extreme cold), or to take advantage of wind direction of a different altitude. Normal descents take place at a con- stant airspeed and constant angle of descent (3 degree final approach at most airports). The pilot controls the angle of descent by varying engine power and pitch angle (lowering the nose) to keep the airspeed constant. At the beginning of and during the descent phase, the engine noise diminishes further as the engines are operated at low power settings. However, towards the end of the descent phase, the passenger can feel further accelerations and an increase in the noise. This is to realize the “final approach” before taking “landing posi- tion”. Landing Landing is the last part of a flight, where the aircraft returns to the ground. Aircraft usually land at an airport on a firm runway, generally constructed of asphalt concrete, concrete, gravel or grass. To land, the airspeed and the rate of descent are reduced to where the object descends at a slow enough rate to allow for a gentle touch down. Landing is accomplished by slowing down and descending to the runway. This speed reduction is accomplished by reducing thrust and/or inducing a greater amount of drag using flaps, landing gear or speed brakes. As the plane approaches the ground, the pilot will execute a flare (roundout) to induce a gentle landing. Although the pilots are trained to perform the landing operation, there are “Instrument Landing Systems” in most of the airports to help pilots land the aircrafts. An instrument landing system (ILS) is a ground-based instrument approach system that provides precision guid- ance to an aircraft approaching and landing on a runway, using a combination of radio signals and, in many cases, high-intensity lighting arrays to enable a safe landing during instrument meteorological conditions (IMC), such as low ceilings or reduced visibility due to fog, rain, or blowing snow. At the beginning of the landing phase, the pas- sengers will hear the opening of the doors of the landing gears. As the landing gears are deployed, they will create an additional drag and an additional noise. Immediately after touch-down, the passengers can hear a blowing sound, sometimes with increasing engine sound. This is the engine’s thrust reverses, helping the aircraft to slow down to taxi speeds by redirecting the airflow of the engines for- ward. Once the aircraft is decelerated to low speed, it can taxi to the terminal building.

AIRPLANE PARTS & FUNCTIONS

Birds could fly; man wanted to. This desire to launch our bi-pedal forms into the skies led to centuries of scientists and dreamers trying to find out exactly how those birds managed such a seemingly effortless feat. It wasn’t until 1903 that the Wright brothers succeeded in building the first self-powered, fixed-wing airplane. Its first flight lasted a mere 12 seconds and covered 120 feet. Since then man has created planes that fly faster and farther, but the basic parts of an airplane, and how they work, remain pretty much the same. Wings Wings are the key to flight. Take away the engine, and you have a glider, which, once towed into the sky by another plane, catches the air currents and stays aloft quite nicely. Wings are designed with a thicker rounded edge along the front that tapers to a point across the back. Looking at the wing from the side, the bottom is fairly flat, while the top is curved. The air flowing over the top of the wing creates an area of low pressure, which pulls the plane into the air, creating lift. Flaps, found on the back of the wings, are controlled by the pilot to either increase the lift or to slow the plane down. Early airplane wings were made of light wood and fabric, while today’s plane wings are usually made of metal. Sometimes, wings also hold the plane’s fuel tanks. Fuselage - The Cockpit The fuselage is the long tube-shaped structure that holds the pilot, crew, passengers and cargo. The cockpit, in the front, is where the pilot sits and controls the plane. A mass of dials and switches keeps track of all the plane's systems; among them are altitude, how high you are flying; your compass reading, where exactly you are in the sky; and a gauge that measures fuel consumption. The yoke, sort of an odd-looking steering wheel, along with the rudder pedals on the floor of the plane, are the main controls. The yoke steers the plane up or down and keeps the plane flying level, also known as attitude. On small planes, the yoke is manually controlled by the pilot; it feels like manipulating a car steering wheel, but without the power steering. The rudders help with turning the plane. Larger planes use hydraulics to help the pilot control the craft.

Fuselage – Cabin The section in back of the cockpit is the cabin; on small planes, like the Cessna 172 Skyhawk (cessna.com) or the Piper Cub (piper.com), the cabin and cockpit are all in one unit. On larger planes, including commercial jets, these two sections of the plane are separated. Commercial jets usually have cabins with first-class and coach sections; first class has wider seats and more services than coach. Business class, a sort of hybrid between the two classes, is between the two on some flights. In the Boeing 747 (boeing.com), the cabin has two floors; the first class section is upstairs. The cabin also houses the restrooms, galleys, or kitchens, and seating for the flight attendants. Each passenger seat offers emergency oxygen masks and call buttons for the attendants. Tail Section The tail section of a plane not only provides balance, it helps to steer the plane. Tails have two small horizontal pieces that look like mini-wings and a vertical fin. On the horizontal pieces are the elevators, small flaps controlled by the yoke in the cockpit. If the elevator points up, the nose of the plane goes up; if they point down, the plane also noses downward. An elevator pointing straight back keeps the plane in level flight. The outer edge of the vertical fin holds the rudder, and if the pilot pushes the left rudder pedal, the rudder moves left, while the plane turns right. Pressing the right rudder pedal has the opposite effect. Undercarriage - Landing Gear A plane's landing gear must be strong enough to absorb the stresses of take-offs and landings. Small planes usually have one of two types of landing gear. Conventional landing gear, in which two wheels are toward the front of the aircraft and a tiny third wheel is under the base of the tail, is the most basic. A tricycle landing gear system, which has two main wheels and another wheel under the nose of the plane, makes the plane easier to control. Large aircraft use tandem landing gear, pairs of landing wheels that sit under the plane’s fuselage. As an example, a Boeing 747 has 16 main landing wheels and two additional nose wheels. In the larger planes, as well as on some small craft, the landing gear is retracted into the fuselage during flight, which makes the plane more aerodynamic. The Engine

Birds flap their wings to create lift, but since airplane wings are fixed in place, the lift comes from the engine, usually found in the front of the plane or on the wings. Single engine craft like the Cessna 172 Skyhawk have one engine in front of the cockpit. The pilot can usually see the tip of the propeller blade, the spinning propeller that makes the plane move forward, through the windshield. At a certain point the plane is moving fast enough that the wings attain lift, and the plane leaves the ground. Twin engine planes have one engine on each wing, while passenger jets, depending on their size, could have one or two engines on each wing. In the case of the Lockheed L-1011, now retired, the plane had one engine on the tail and one on each wing. Jet engines, which have no propellers, use the oxygen in the air combined with a fuel source to create lift. The oxygen is sucked into the front of the engine and pushed out the rear, propelling the plane forward.

INTERNATIONAL AIR LAW

Aviation Law is one of the specialty field in Studies of Law. Air Law is a general viewpoint that covers the special characteristics and demands of aviation field. There is no governing body with the right to frame the air laws governing all states in the legal sense or there is not any international law. But the phrase Air Law is used to describe a system of implicit and explicit agreements that the nations together. These agreements are known as conventions. There are numerous conventions such as Chicago, Rome, Tokyo, Geneva, and few more. Let us discuss more about the aviation law. What is Air Law It is a branch of law that is concerned with air transport operations, and all the associated legal and business concerns. This is a series of rules that governs the use of airspace for aviation, and its benefits for the general public and the nations of the world. The first attempt to set the air law was made around 1910, when German air balloons repeatedly trespassed over French territory. The French government wanted both the governments to come together to form an agreement to resolve the problem. The Paris Conference of 1910 was in favor of the sovereignty of states in the space above their territories. It started developing further when after the World War I, the first scheduled flight from Paris to London took its first flight in 1909. Public International Air Law: Chicago Convention A Convention on International Civil Aviation was signed at Chicago on 7th December, 1944. It established specific principles in order to develop international civil aviation in a safe and orderly manner. It also ensures that international air transport services are established on the basis of fair opportunity for participating countries. The convention formed the International Civil Aviation Organization (ICAO), the Canada-based agency of the United Nations. It sets the principles of international air navigation and works to:

• Ensure a well-ordered growth of international civil aviation throughout the

world.

• Encourage aircraft design and operation for peaceful and constructive purposes.

• Promote the development of airways, airports, and air navigation facilities for

international civil aviation.

• Meet the safety, regularity, efficiency, and economical air transport needs of the people around the world.

• Prevent unplanned economic decisions and in turn waste.

• Ensure that each Contracting State has an opportunity to operate international

airlines.

• Encourage flight safety in international air transport.

• Foster the development of all aspects of international civil aviation. Air Law in European Union The laws are regarding the following

• Sovereignty: It is the right of a state to impose its national law on users of its airspace.

• Territory: It is the airspace over and within the territorial borders of a state.

Territorial airspace has no vertical limit. For the states with sea boundaries, territorial airspace extends beyond the land. This limit is internationally agreed limit of the territorial waters.

International Air Laws The three International Air Laws are as follows −

• Public International Law It refers to the process which binds the states and international organizations to agreements with respect to their aviation activities. The activities may be among

various problems of political, technical, economical, financial, social or legal nature. For example, the Chicago Convention, the Geneva Convention, and some international conventions.

• Private International Law It is the series of rules pertaining to the relations between private persons involved in the operation and the use of aircraft. It applies to the travelers and airline staff. For example, the Tokyo Convention frames the prohibition of unlawful acts committed on the aircraft.

• Supranational Law It is a law that a higher body can impose with legal force on one or more states. For example, EU air laws. IOSA and its Importance The IATA Operational Safety Audit (IOSA) is an internationally recognized and accepted system that audits and certifies operational management and control systems in the airlines. IATA formed this certifying evaluation body in 2003. It conducts airline audits according to the aviation laws consistently. The airlines which have no IOSA certification probably either failed in the auditing or they did not participate in auditing at all. Carrying out IOSA audit makes an airline more reliable but the cost of audit is high. Mostly only international airlines participate in the audit as they can bear the cost of audit and implement the changes suggested. The crash-rate, which is measured per specific number of flights, is three times less in the airlines which took IOSA audit than the ones which did not. International Civil Aviation Organization (ICAO) ICAO consists of an Assembly of representatives from the contracting states, a Council of governing bodies out of various subordinate bodies, and a Secretariat. The chief officers are the President of the Council and the Secretary General. ICAO conducts meeting every three years to discuss about the work and to set future policies. The suggestions, standards, and recommendations are amended by the convention. ICAO identifies nine separate geographical regions to plan the provision of air

navigation facilities and on-ground services the aircrafts require for flying in these regions. Freedoms of the Air There are five different freedoms of the air. The first two are technical freedoms followed by three commercial freedoms:

• First Freedom: The right of aircraft from State A to overfly State B without landing.

• Second Freedom: The right of aircraft from State A to land in State B for

technical reasons.

• Third Freedom: The right of aircraft from State A to accept paying traffic from State A and put it down in State B.

• Fourth Freedom: The right of aircraft from State A to pick up paying traffic in

State B and put it down in State A.

• Fifth Freedom: The right of aircraft from State A to take paying traffic from State B to State C.