basicaeronauticschapter3-1

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Basic Aeronautics

Know the principles of basic aeronautics. 1. Describe the theory of flight. 2. Describe airfoils and flight. 3. Describe the effects of relative wind. 4. Describe the effects of angle of attack.

. !dentify the four forces of flight.


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"verview

1. #heory of $light2. Airfoils and $light3. %elative &ind4. Angle of Attack . #he $our $orces of $light


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#heory of $light

' Aerodyna(ics' #he science relating to the effects produced by

air or other gases.

' #he ter( co(es fro( the )reek words aero (eaning air and dynamics (eaning power.

' Ancient )reeks described air as having the*ualities of (oisture and heat. !t was observedto shift in response to heating and cooling.


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#heory of $light

' Aerodyna(ics' A lifting force is re*uired for heavier+than+air

flying. An ob,ect can be pushed upward by

applying (uscle power- an e plosion- a hoist-or other (eans of force.' !t cannot re(ain aloft without decreasing the air

pressure fro( above and increasing lift pressure

fro( below.' !ncreasing the speed of the ob,ect can increase the

flow of air.' #he flying ob,ect (ust be shaped to for( an airfoil.

' Air flows faster over the curved surface of an airfoil.


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#heory of $light

' Aerodyna(ics' Bernoulli principle

' /As the air velocity increases- the pressure

decreases0 and as the velocity decreases- the pressure increases.' A (a,or part of the knowledge base needed in the

design and develop(ent of aircraft.

' ontributed to the work of ).B. enturi- an !talianscientist- who first noted the effects of constrictedchannels on the flow of fluids. A round tube- such asa no le or ,et engine- designed to increase thespeed of flowing gases and li*uids is called aventuri.


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#heory of $light

' Aerodyna(ics' Aristotle

' #he first useful studies of (otion are attributed to

Aristotle. 5e believed there were two kinds of(otion6 natural and violent.' 5e concluded- and later stated as a natural law- that

the velocity or speed of an ob,ect depends entirelyon the force being applied to it and the resistance it(eets. #his law was later proven to be inaccurate.


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#heory of $light

' Aerodyna(ics' )alileo )alilei

' "bserved that an ob,ect in hori ontal (otion would

continue to (ove at the sa(e speed with noadditional force.' #his truth was accepted by 7ir !saac 8ewton and

beca(e the first of three laws of (otion stated by 8ewton.


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#heory of $light

' 8ewton9s :aws of ;otion' $irst :aw of ;otion

' /A body at rest tends to re(ain at rest- and a body in

(otion tends to stay in (otion- unless an outsideforce acts on the body. !t is so(eti(es referred toas the :aw of !nertia.

' "ne of the (ost co((on places people feel this lawis in a fast (oving vehicle. !f you were standinginside a train and it suddenly stopped- you wouldcontinue to (ove forward even though the train hadco(e to a stop.


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#heory of $light

' 8ewton9s :aws of ;otion' 7econd :aw of ;otion

' /#he acceleration of an ob,ect as produced by a net

force- is directly proportional to the (agnitude ofthe net force in the sa(e direction as the net forceand inversely proportional to the (ass of theob,ect.

' 5itting a golf ball is a co((on e a(ple of 8ewton9s second law. #he golf club is a force thatcauses the ball to (ove


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#heory of $light

' 8ewton9s :aws of ;otion' #hird :aw of ;otion

' /&henever one body e erts a force upon a second

body- the second e erts an e*ual and opposite forceupon the first body. 7i(ply stated- $or everyaction there is an e*ual and opposite reaction.


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#heory of $light

' 8ewton9s :aws of ;otion' #hird :aw of ;otion

' #his law is e e(plified by what happens if you step

off a boat onto the shore. As you (ove forwardtoward the shore- the boat tends to (ove in theopposite direction.


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#heory of $light

' Acceleration ' #he rate of increase in the velocity of

so(ething.

' %epresents a change in velocity .' elocity

' #he rate of (otion in a given direction.

' #he change of rate of (otion in a givendirection per unit of ti(e.


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#heory of $light

' $orce' #he power or energy e erted against a

(aterial body in a given direction.

' $orce has both (agnitude and direction.' ;ass

' #he *uantity of (aterial


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#heory of $light

' #he four forces in balance with oneanother hold the plane in the air.

' #he four forces are lift- weight- thrust-

and drag.


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%elative &ind

' #he (ove(ent of the aircraft through theair creates the relative wind.

' #he ter( relative wind (eans the wind

that is (oving past the airfoil and thedirection of the wind is parallel to theflight path and relative to the attitude of

position of the airfoil.' #he pilot controls the direction of the

relative wind.


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Angle of Attack

' $or(ed by the cord of the airfoil and thedirection of the relative wind or betweenthe chord line and the flight path.

' !s not constant during a flight. !t changesas the pilot changes the attitude of theaircraft.

' "ne of the factors that deter(ines theaircraft9s rate of speed through the air.


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#he $our $orces of $light

' According to the Bernoulli >rinciple-there is an increase in the velocity of airas the airflow around an airfoil shape0

therefore- there is an increase of therelative wind as it flows above and belowthe surface of the airplane wing.


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' :ift can be increased in two ways' !ncreasing the forward speed of the airplane.' !ncreasing the angle of attack.

' #he pilot can increase the forward speedof the aircraft by applying (ore power.


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' :ift ariables' #he pilot (ust have so(e way to control the

a(ount of lift the airfoils generate.

' #here are variables acting on the a(ount oflift generated.


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' Angle of Attack


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' Angle of Attack ' #he su( of all the tiny forces over the

surface of the wing is called the resultant.


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' Angle of Attack ' #his resultant has (agnitude- direction- and

location. #he point of intersection of the

resultant with the chord of the wing is calledthe center of pressure < ?>=.


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' Angle of Attack ' #he angle at which lift stops increasing and begins to decrease is called the burble point.


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' Angle of Attack ' #he point at which the a(ount of lift

generated is no longer sufficient to support

the aircraft in air is called the stalling point.


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' elocity of %elative &ind' #he velocity of the airfoil through the air is

another i(portant factor in deter(ining the

a(ount of lift generated.' !f an airfoil is (ade to travel faster throughthe air- greater pressure differences betweenthe lower and upper surfaces of the airfoil

result.


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' :ift ariables' elocity of %elative &ind


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' Air Density and :ift' :ift varies directly with density. !f flying at

1@- feet where the density is about half

that at sea level- an aircraft will need totravel 1.414 ti(es as fast as it would at sealevel to (aintain altitude.

' !f so(ething reduces the lift by half- we will

have to increase the speed so that the s*uareroot of the new velocity is twice the s*uareof the original velocity.


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' Airfoil 7hape' !t is e tre(ely i(portant to preserve the

characteristic curve that the designers built

into the airfoil.' Dents- (ud- and ice are three co((on thingsthat can spoil the built+in shape of the airfoiland interfere with the perfor(ance of the

entire aircraft.


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' &ing Area and :ift' #he greater the surface area of the wing- the

greater the a(ount of lift that will be

generated.' )liders and sailplanes are very goode a(ples of how a large wing surfacegenerates lift.


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' &eight' #here is a point in the relationship of airfoil

to angle of attack where lift is destroyed and

the force of gravity


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' &eight' #here is another situation where lift can no

longer overco(e weight.

' #he at(osphere beco(es less and less denseas altitude increases. ' #he airplane (ust be constructed of the

lightest weight (aterials that can be used. ' #he weight of whatever the airplane carries

also receives very careful consideration.


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' #hrust and Drag' #hrust is the force that propels the aircraft

forward.

' An airplane cannot gain altitude or (aintainstraight and level flight unless its engine is producing enough thrust.

' &ithout the needed thrust- weight has (oreinfluence than lift and pulls the airplanetoward the ground.


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7u((ary

1. #heory of $light2. Airfoils and $light3. %elative &ind4. Angle of Attack . #he $our $orces of $light

basicaeronauticschapter3-1

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