Question 259-1 : Which statement about the effects on drag of fitting external tip tanks to the wings of an aeroplane is correct i parasite drag increasesii induced drag decreases ? [ Explanation maintenance ]

Question 259-2 : Which statement about the effects on drag of removing external tip tanks from the wings of an aeroplane is correct i parasite drag decreasesii induced drag increases ?

I is correct ii is correct.

The external wing tip tanks act like winglets they reduce the wing tip vortices induced drag decreases but they increase the parasite drag form drag + skin friction drag com encom080 1125jpg siai marchetti sf 260 with tip tanks

Question 259-3 : Which statement about an aeroplane leaving ground effect is correct i the downwash angle increasesii the induced angle of attack increases ?

I is correct ii is correct.

Ground effect changes airflow com encom080 821jpgwhen leaving the ground effect it requires an increase in angle of attack to maintain the same cl the induced angle increases

Question 259-4 : Regarding deep stall characteristics identify whether the following statements are correct or incorrect i the combination of a wing with sweepback and a t tail make an aeroplane prone to deep stallii a stick shaker system is fitted to an aeroplane that exhibits abnormal stall characteristics ?

I is correct ii is incorrect.

There is a tendency for the swept wing to develop a strong spanwise flow towards the wingtip when the wing is at high angles of attack com encom080 27jpgstall occurs at the wingtips first resulting in a shift of the center of lift of the wing in a forward direction relative to the center of gravity of the airplane causing the nose to pitch upit is a characteristic of t tail aircraft to pitch up viciously when stalled in extreme nose high attitudes making recovery difficult or violentthe tailplane and elevator are in the path of the separated airflow from the wing com encom080 810jpgthe stick pusher and not the stick shaker inhibits this type of stallat approximately one knot above stall speed pre programmed stick forces automatically move the stick forward preventing the stall from developing

Question 259-5 : Which statement about an aeroplane entering ground effect is correct i the downwash angle decreasesii the induced angle of attack remains constant ?

I is correct ii is incorrect.

Ground effect changes airflow com encom080 821jpgwhen entering the ground effect it requires a decrease in angle of attack to maintain the same cl the induced angle decreases

Question 259-6 : Which statement about an aeroplane entering ground effect is correct i the downwash angle decreasesii the induced angle of attack increases ?

I is correct ii is incorrect.

Ground effect changes airflow com encom080 821jpgwhen entering the ground effect it requires a decrease in angle of attack to maintain the same cl the induced angle decreases

Question 259-7 : Which statement about an aeroplane leaving ground effect is correct i the downwash angle increasesii the induced angle of attack decreases ?

I is correct ii is incorrect.

Ground effect changes airflow com encom080 821jpgwhen leaving the ground effect it requires an increase in angle of attack to maintain the same cl the induced angle increases

Question 259-8 : Regarding deep stall characteristics identify whether the following statements are correct or incorrect i a wing with forward sweep and a low horizontal tail makes an aeroplane prone to deep stallii a stick shaker system is fitted to an aeroplane that exhibits abnormal stall characteristics ?

I is incorrect ii is incorrect.

There is a tendency for the swept wing to develop a strong spanwise flow towards the wingtip when the wing is at high angles of attackstall occurs at the wingtips first resulting in a shift of the center of lift of the wing in a forward direction relative to the center of gravity of the airplane causing the nose to pitch up but on a wing with forward sweep the stall occurs at the wing root example of a aircraft with a wing with forward sweep com encom080 824jpghfb 320 hansa jetit is a characteristic of t tail aircraft to pitch up viciously when stalled in extreme nose high attitudes making recovery difficult or violentthe tailplane and elevator are in the path of the separated airflow from the wing it is not the case for a low horizontal tail com encom080 810jpgthe stick pusher and not the stick shaker inhibits this type of stallat approximately one knot above stall speed pre programmed stick forces automatically move the stick forward preventing the stall from developing

Question 259-9 : Which statement is correct i a stick pusher activates at a lower angle of attack than a stick shakerii a stick shaker prevents the pilot from increasing the angle of attack further ?

I is incorrect ii is incorrect.

A stick pusher activates at a higher angle of attack than a stick shakera stick pusher prevents the pilot from increasing the angle of attack furthera stick pusher is a device installed in some fixed wing aircraft to prevent the aircraft from entering an aerodynamic stall some large fixed wing aircraft display poor post stall handling characteristics or are vulnerable to deep stall to prevent such an aircraft approaching the stall the aircraft designer may install a hydraulic or electro mechanical device that pushes forward on the elevator control system whenever the aircraft's angle of attack reaches the pre determined value and then ceases to push when the angle of attack falls sufficientlyvdo927you can see that first the stick shaker is activated and if the pilot do not reacts and the angle of attack continues to increase the stick pusher is activateda stick shaker is a mechanical device to rapidly and noisily vibrate the control yoke the 'stick' of an aircraft to warn the pilot that the speed is close to the stall speed a stick shaker do not prevent the pilot from increasing the angle of attack further it just warns the pilot

Question 259-10 : Which of these statements about the strength of wing tip vortices are correct or incorrect i assuming no flow separation the strength of wing tip vortices is not affected by angle of attackii the strength of wing tip vortices decreases as the aspect ratio decreases ?

I is incorrect ii is incorrect.

Formation of vortices the action of the airfoil that gives an aircraft lift also causes induced drag when an airfoil is flown at a positive aoa a pressure differential exists between the upper and lower surfaces of the airfoil the pressure above the wing is less than atmospheric pressure and the pressure below the wing is equal to or greater than atmospheric pressure since air always moves from high pressure toward low pressure and the path of least resistance is toward the airfoil's tips there is a spanwise movement of air from the bottom of the airfoil outward from the fuselage around the tips this flow of air results in 'spillage' over the tips thereby setting up a whirlpool of air called a 'vortex'just as lift increases with an increase in aoa induced drag also increases this occurs because as the aoa is increased there is a greater pressure difference between the top and bottom of the airfoil and a greater lateral flow of air consequently this causes more violent vortices to be set up resulting in more turbulence and more induced dragthe strength of the wingtip vortices is determined by the magnitude of the pressure difference between the upper and lower wing surfaces and by the time during which this pressure difference acts to drive the air into the vortices the greater the pressure difference or the longer the time available the stronger the vortices will bethe time during which the pressure difference acts upon the air is proportional to the time it takes the air to pass from the leading edge to the trailing edge of the wing so for any given airspeed the length of the wing chord determines the time taken this means that decreasing the chord length will decrease the vortex strength which will decrease the stalling angle and the dragthe intensity or strength of the vortices is directly proportional to the weight of the aircraft and inversely proportional to the wingspan and speed of the aircraftgood answers for this kind of questions assuming no flow separation the strength of wing tip vortices increases as the angle of attack increasesassuming no flow separation the strength of wing tip vortices decreases as the angle of attack decreasesthe strength of wing tip vortices decreases as the aspect ratio increasesthe strength of wing tip vortices increases as the aspect ratio decreases

Question 259-11 : Which of these statements about the effect of wing sweep on centre of pressure location are correct or incorrect i the centre of pressure on a straight wing moves aft as the angle of attack approaches and exceeds the critical angle of attackii the centre of pressure on a strongly swept back wing ?

I is correct ii is correct.

Straight wing the centre of pressure moves forward as the angle of attack increases until it approaches and exceeds the critical angle of attack then it moves aft at the stallswept back wing there is a tendency for the swept wing to develop a strong spanwise flow towards the wingtip when the wing is at high angles of attack com encom080 27jpgstall occurs at the wingtips first resulting in a shift of the center of pressure of the wing in a forward direction relative to the center of gravity of the airplane causing the nose to pitch up

Question 259-12 : Considering subsonic incompressible airflow through a venturi which statement is correct i the static pressure in the throat is lower than in the undisturbed airflowii the speed of the airflow in the throat is higher than in the undisturbed airflow ?

I is correct ii is correct.

Img com encom080 815jpgstatic pressure decreases in a venturi and airflow speed increases

Question 259-13 : Which statement about an aeroplane leaving ground effect at constant angle of attack is correct i the lift coefficient cl decreasesii the induced drag coefficient cdi increases ?

I is correct ii is correct.

Ground effect changes airflow com encom080 821jpgwhen leaving the ground effect the lift coefficient cl decreases it requires an increase in angle of attack to maintain the same clthe induced angle increases so the induced drag coefficient cdi increases

Question 259-14 : Which statement about an aeroplane entering ground effect is correct i the downwash angle decreasesii the induced angle of attack decreases ?

I is correct ii is correct.

Ground effect changes airflow com encom080 821jpgwhen entering the ground effect it requires a decrease in angle of attack to maintain the same cl thus if the angle of attack is maintain constant the question states entering ground effect at constant angle of attack the lift coefficient cl increaseswhen entering ground effect induce flow reduces and the induced angle of attack decreases thus the induced drag coefficient cdi decreases

Question 259-15 : Which of these statements about induced drag are correct or incorrect i induced drag decreases as angle of attack decreasesii at constant load factor induced drag decreases with decreasing aeroplane mass ?

I is correct ii is correct.

Induced drag increases as angle of attack increases since induced drag is induced by lift as you increase lift by increasing the angle of attack cl increases the induced drag will increaseinduced drag decreases with decreasing aeroplane mass if less lift has to be produced less induced drag will be generated

Question 259-16 : The parameters that can be read from the aeroplane parabolic polar curve are the ?

Minimum glide angle and the parasite drag coefficient.

The polar curve of an aerofoil section is a graphic relationship between lift coefficient cl and drag coefficient cd com encom080 1264jpgwhere the line crosses the cl=0 axis there is no lift and therefore no induced drag so cd at that point is from parasite drag onlyangle of glide is clcd the liftdrag ratio if the liftdrag ratio is 10 1 then the glide angle is 1 in 10 the tangent to the curve from the clcd origin shows the best clcd ratio and thus the best glide angle you can get rate of descent would depend on what speed you were doing down the hill and that is not shown on the polar diagramthe polar diagram shows coefficients only to get real world data you have to add in all the other bits of the lift and drag equations like s and rho and v squared

Question 259-17 : For most jet transport aeroplanes slat extension has ?

A greater effect on stall speed than flap extension.

Question 259-18 : One advantage of mounting the horizontal tailplane on top of the vertical fin is ?

To improve the aerodynamic efficiency of the vertical fin.

Question 259-19 : Which drag components make up parasite drag 1 pressure drag2 friction drag3 induced drag4 interference dragthe combination that regroups all of the correct statements is ?

1 2 4.

Question 259-20 : The transition point is where the boundary layer changes from ?

Laminar into turbulent.

Question 259-21 : As angle of attack is increased on a conventional low speed aerofoil at low subsonic speeds flow separation normally starts on the ?

Upper surface near the trailing edge.

Question 259-22 : Assuming no flow separation when speed is decreased in straight and level flight on a positively cambered aerofoil what happens to the 1 centre of pressureand2 the magnitude of the total lift force ?

1 moves forward and 2 remains constant.

The pressure created by an aerofoil at any point may be represented by a vector at right angles to its surface whose length is proportional to the difference between absolute pressure at the point and the free stream static pressureall of them can be represented by a single vector acting at a particular point called the centre of pressure 669the centre of pressure is a theoretical point on the chord line through which the resultant of all forces the total reaction is said to actits position is usually around 25% of the way from the leading edge simply because more lift is generated there but it moves steadily forward as the angle of attack is increased until just before the stalling angle when it moves rapidly backwards the centre of pressure's most forward point is just before the stalling angle this is why an aeroplane's nose drops when the wings stall and the centre of pressure moves behind the cgthus when speed is increased in straight and level flight on a positively cambered aerofoil you have to decrease the angle of attack to keep the the total lift force constant and the point where the resultant of all forces are acting the centre of pressure moves aft

Question 259-23 : Given the following characteristic points on a jet engine aeroplane's polar curve 1 clmax2 long range cruise zero wind 3 maximum lift to drag ratio4 minimum rate of descent assume zero thrust 5 maximum range cruise zero wind arrange these points in order of increasing angle of attack ?

2 5 3 4 1.

The aerofoil polar is a graph of the relation between the lift coefficient and the drag coefficient com encom080 918jpg

Question 259-24 : Assuming standard atmospheric conditions in order to generate the same amount of lift as altitude is increased an aeroplane must be flown at ?

A higher tas for any given angle of attack.

Question 259-25 : In comparison to a conventional aerofoil section typical shape characteristics of a supercritical aerofoil section are ?

A larger nose radius flatter upper surface and negative as well as positive camber.

com encom080 958jpg

Question 259-26 : Induced drag is the result of ?

Downwash generated by tip vortices.

Question 259-27 : Given an aeroplane in steady straight and level flight at low speed and considering the effects of cg location and thrust the highest value of wing lift occurs at ?

Forward cg and idle thrust.

Img683with a forward cg the horizontal stabiliser produces a down force the force of lift must balance weight and the tail downward force at high angle of attack we are in steady flight at low speed any thrust from the engines would tend to produce a vector force upwards this would help lift thus at idle thrust the wing lift force would be at it highest valuethis question also appears with the opposite statement at the exam 'the lowest value of wing lift occurs at aft cg and take off thrust' 684

Question 259-28 : The main function of a trailing edge flap is to ?

Increase the maximum lift coefficient of the wing.

Question 259-29 : Stall speed ias varies with ?

Weight.

Question 259-30 : What will happen if a large transport aeroplane slowly decelerates in level flight from its cruise speed in still air at high altitude ?

Question 259-31 : Which of the following increases the maximum duration of a glide ?

A decrease in mass.

A headwind will always reduce the glide range and a tailwind will always increase the glide rangeas mass increases the best glide ratio is achieved at higher speeds to increase the speed you must increase the descent angle the glide duration will be reduceda decrease in mass will permit to increase the duration of the glide

Question 259-32 : Wing spoilers are deflected symmetrically in flight in order to ?

Decelerate the aeroplane andor increase its rate of descent.

A spoiler is a device intended to reduce lift in an aircraft spoilers are plates on the top surface of a wing which can be extended upward into the airflow and spoil it by doing so the spoiler creates a carefully controlled stall over the portion of the wing behind it greatly reducing the lift of that wing section spoilers differ from airbrakes in that airbrakes are designed to increase drag making little change to lift while spoilers reduce lift as well as increasing dragif in flight spoilers are deployed while maintaining level flight they decelerate the aeroplaneif in flight spoilers are deployed while descending and maintaining speed they increase its rate of descent com encom080 977jpg

Question 259-33 : A positively cambered aerofoil will generate zero lift ?

At a negative angle of attack.

Img com encom080 878jpga symmetrical aerofoil need to have a positive pitch to produce lift if the pitching moment is zero the lift is zero a positively cambered aerofoil produces lift with a zero pitching moment thus not to produce lift it need a negative pitching moment

Question 259-34 : The lift coefficient cl versus angle of attack curve of a negatively cambered aerofoil section intersects the horizontal axis of the graph ?

To the right of the origin.

com encom080 984jpga negatively cambered aerofoil section produces lift at positive angle of attack only in our example at approximately 3° angle of attack stanley hi there was no graph with the question best regardsthis is normal there is no graph with this question at the exam you need to know the shape of the claoa curve

Question 259-35 : Regarding the lift formula if density doubles lift will ?

Also double.

Lift formula lift = 12 rho cl x v² x swhere '12 rho' is dynamic pressure'cl' is coefficient of lift'v' is speed in ms's' is wing areaif density is double lift will also double

Question 259-36 : Assuming all bodies have the same cross sectional area and are in motion which body will have the highest pressure drag err a 081 986 ?

Body b.

com encom080 986jpg

Question 259-37 : When a wing spoiler is extended at constant angle of attack ?

Drag increases but lift decreases.

When you deploy the spoilers you will need to increase angle of attack to restore the coefficient of lift to that required at the lower speed the aircraft will be travelinghowever if the angle of attack is unchanged the aircraft will no longer produce sufficient lift to oppose the weight and therefore the aircraft will descendright answer drag increases but lift decreases

Question 259-38 : The point where the single resultant aerodynamic force acts on an aerofoil is called ?

Centre of pressure.

The pressure created by an aerofoil at any point may be represented by a vector at right angles to its surface whose length is proportional to the difference between absolute pressure at the point and the free stream static pressureall of them can be represented by a single vector acting at a particular point called the centre of pressure 669the centre of pressure is a theoretical point on the chord line through which the resultant of all forces the total reaction is said to actits position is usually around 25% of the way from the leading edge simply because more lift is generated there but it moves steadily forward as the angle of attack is increased until just before the stalling angle when it moves rapidly backwards the centre of pressure's most forward point is just before the stalling angle this is why an aeroplane's nose drops when the wings stall and the centre of pressure moves behind the cgthus when speed is increased in straight and level flight on a positively cambered aerofoil you have to decrease the angle of attack to keep the the total lift force constant and the point where the resultant of all forces are acting the centre of pressure moves aft

Question 259-39 : Wing loading is the ratio between ?

Question 259-40 : Increasing the aspect ratio of a wing ?

Decreases induced drag.