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Which of these statements about the strength of wing tip vortices are correct ? [ Certification weather ]

Question 224-1 : I is correct ii is correct i is correct ii is incorrect i is incorrect ii is correct 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 drag .the 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 be .the 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 drag .the 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 aircraft .good answers for this kind of questions .assuming no flow separation the strength of wing tip vortices increases as the angle of attack increases .assuming no flow separation the strength of wing tip vortices decreases as the angle of attack decreases .the strength of wing tip vortices decreases as the aspect ratio increases .the strength of wing tip vortices increases as the aspect ratio decreases exemple 324 I is correct, ii is correct.I is correct, ii is correct.

Considering subsonic incompressible airflow through a venturi which statement ?

Question 224-2 : I is incorrect ii is incorrect i is correct ii is incorrect i is correct ii is correct i is incorrect ii is correct

Img /com en/com080 815 jpg.static pressure decreases in a venturi and airflow speed increases exemple 328 I is incorrect, ii is incorrect.I is incorrect, ii is incorrect.

Assuming no flow separation which of these statements about the flow around an ?

Question 224-3 : I is correct ii is correct i is incorrect ii is incorrect i is incorrect ii is correct i is correct ii is incorrect

exemple 332 I is correct, ii is correct.I is correct, ii is correct.

Considering subsonic incompressible airflow through a venturi which statement ?

Question 224-4 : I is correct ii is incorrect i is incorrect ii is incorrect i is correct ii is correct i is incorrect ii is correct

Img /com en/com080 815 jpg.static pressure decreases in a venturi and airflow speed increases exemple 336 I is correct, ii is incorrect.I is correct, ii is incorrect.

Assuming isa conditions and no compressibility effects if an aeroplane ?

Question 224-5 : Tas is lower at the lower altitude ias is lower at the lower altitude ias is higher at the lower altitude tas is higher at the lower altitude

.in straight and level flight lift does not change as it is only balancing against weight ..aircraft is maintaining level flight and therefore lift cannot change ..lift = cl 1/2rho v² s..cl = lift coefficient.rho = density.v = tas in m/s .s = surface..at the same angle of attack same cl with 'rho' increasing with decreasing altitude since surface 's' does not change only tas can be must be reduced exemple 340 Tas is lower at the lower altitude.Tas is lower at the lower altitude.

The main purpose of a boundary layer fence on a swept wing is to ?

Question 224-6 : Improve the low speed handling characteristics improve the high speed handling characteristics increase the critical mach number improve the lift coefficient of the trailing edge flaps

.the spanwise flow encountered with swept wings may be reduced by the use of stall fences which are thin plates parallel to the axis of symmetry of the airplane . /com en/com080 1207 jpg.in this manner a strong boundary layer buildup over the ailerons is prevented .notice recent aircrafts do not use boundary layer fence anymore exemple 344 Improve the low speed handling characteristics.Improve the low speed handling characteristics.

The stall speed decreases . all other relevant factors are constant ?

Question 224-7 : When during a manoeuvre the aeroplane nose is suddenly pushed firmly downwards e g as in a push over in a horizontal turn when flaps are retracted when the cg is moved forward

.when flaps are retracted the stall speed increases you will stall at a higher speed than the speed with flaps deployed .stall speed is based on 1g flight when you do a push over load factor decreases .stall speed changes at the square root of the load factor .vs at 1g = 100 kt .if load factor is 0 5g now stall speed is square root 0 5 = 0 7 x 100 kt = 70 kt exemple 348 When, during a manoeuvre, the aeroplane nose is suddenly pushed firmly downwards (e.g. as in a push over).When, during a manoeuvre, the aeroplane nose is suddenly pushed firmly downwards (e.g. as in a push over).

The load factor is greater than 1 one ?

Question 224-8 : When lift is greater than weight in steady wings level horizontal flight during a wings level stall before recovery when lift is less than weight

.dividing lift by weight gives load factor .load factor increases in a turn and in a pull up manoeuvre those actions require more lift exemple 352 When lift is greater than weight.When lift is greater than weight.

Which of these statements about weight or mass is correct ?

Question 224-9 : In the si system the unit of measurement for weight is the newton in the si system the unit of measurement for weight is the kilogram the weight of an object is independent of the acceleration due to gravity the mass of an object depends on the acceleration due to gravity

The si unit of weight is the newton n = kg m/s² exemple 356 In the si system the unit of measurement for weight is the newton.In the si system the unit of measurement for weight is the newton.

What is the effect of winglets on the drag of the wing ?

Question 224-10 : Increase parasite drag decrease induced drag increase induced drag decrease friction drag increase friction drag decrease form drag increase induced drag decrease interference drag

exemple 360 Increase parasite drag, decrease induced drag.Increase parasite drag, decrease induced drag.

If the wing area is increased lift will ?

Question 224-11 : Increase because it is directly proportional to wing area increase with the square of the wing area remain constant not change because the lift coefficient is constant

exemple 364 Increase because it is directly proportional to wing area.Increase because it is directly proportional to wing area.

Which of these statements about stall speed is correct ?

Question 224-12 : Increasing forward sweep increases stall speed increasing forward sweep decreases stall speed increasing wing anhedral decreases stall speed decreasing wing anhedral decreases stall speed

.the effect of increasing wing sweep angle is to decrease the lift curve slope and clmax as depicted below . /com en/com080 999 jpg.while the swept wing offers a strong transonic drag reduction the lift penalty at high angle of attack is substantial as a wing is swept clmax decreases . /com en/com080 1226 jpg.spanwise airflow over a forward swept wing is the reverse of a conventional swept wing but the stall speed increases or decreases in a same way exemple 368 Increasing forward sweep increases stall speed.Increasing forward sweep increases stall speed.

The lift formula can be written as . rho = density ?

Question 224-13 : L = cl * 1/2rho * v² * s l = w l = cl * 2rho * v² * s l = n * w

Where .'1/2 rho' is dynamic pressure .'cl' is coefficient of lift .'v' is speed in m/s .'s' is wing area exemple 372 L = cl * 1/2rho * v² * s.L = cl * 1/2rho * v² * s.

During a straight steady climb and with the thrust force parallel to the flight ?

Question 224-14 : Lift is the same as during a descent at the same angle and mass lift is greater than weight lift is equal to weight drag is equal to thrust

.during climb and descent lift is lower than weight .lift is a vertical vector .lift in climb or descent = weight x cos climb angle exemple 376 Lift is the same as during a descent at the same angle and mass.Lift is the same as during a descent at the same angle and mass.

Assuming no compressibility effects induced drag at constant ias is affected by ?

Question 224-15 : Aeroplane mass outside air temperature altitude engine thrust

exemple 380 Aeroplane mass.Aeroplane mass.

Given that .pstat = static pressure .rho = density .pdyn = dynamic pressure ?

Question 224-16 : Pstat + 1/2rho * tas² = constant pdyn + pstat = 1/2rho * tas² pstat + 1/2rho * tas² = pdyn ptot = 1/2rho * ias² + pstat

.dynamic pressure is '1/2 rho tas²' .bernoulli's theorem is .pt = ps + pd.then if pd inscreases ps decreases as pt always remains constant exemple 384 Pstat + 1/2rho * tas² = constant.Pstat + 1/2rho * tas² = constant.

The point in the diagram giving the lowest speed in unaccelerated flight is . ?

Question 224-17 : Point 4 point 1 point 2 point 3

Img /com en/com080 1264 jpg. exemple 388 Point 4.Point 4.

The point in the annex showing zero lift is . err a 081 1269 ?

Question 224-18 : Point a point b point c point d

exemple 392 Point a.Point a.

If the airspeed reduces in level flight below the speed for maximum l/d the ?

Question 224-19 : Increase because of increased induced drag reduce because of reduced induced drag increase because of increased parasite drag reduce because of reduced friction drag

.total drag is lowest when parasite drag is equal to the induced drag . /com en/com032 209 jpg.if the airspeed reduces below the speed for maximum lift/drag ratio then induced drag increases thus total drag increases .notice if the airspeed increases above the speed for maximum l/d total drag also increases due to increase of the parasite drag .parasite drag only varies with speed and is directly proportional to v² .induced drag varies with lift speed and aspect ratio is inversely proportional to aspect ratio and v² so multiply by 1/v² exemple 396 Increase because of increased induced drag.Increase because of increased induced drag.

Slat or flap asymmetry occurring after either extension or retraction may have ?

Question 224-20 : Slat asymmetry causes a yawing moment whereas flap asymmetry causes a large rolling moment slat and flap asymmetry both cause a large rolling moment slat asymmetry causes a large rolling moment whereas flap asymmetry causes a large yawing moment slat and flap asymmetry both cause a large yawing moment

At high speed the angle of attack will be small and with an asymmetric leading edge slat deployment there will be little change in cl but cd would increase on the deployed slat turbulent boundary layer this causes yaw which can be controlled by rudder .however at lower speeds and high angle of attack a large change in clmax will occur between the wings with a flap asymmetry this would then lead to a strong rolling moment exemple 400 Slat asymmetry causes a yawing moment, whereas flap asymmetry causes a large rolling moment.Slat asymmetry causes a yawing moment, whereas flap asymmetry causes a large rolling moment.

Which of the following variables are required to calculate lift from the lift ?

Question 224-21 : Dynamic pressure lift coefficient and wing area square root of wing area density and wing loading total pressure and wing area only angle of attack aspect ratio and dynamic pressure

.lift formula = 1/2 rho cl x v² x s..where .'1/2 rho v²' is dynamic pressure rho = density v = speed in m/s .'cl' is coefficient of lift .'s' is wing area exemple 404 Dynamic pressure, lift coefficient and wing area.Dynamic pressure, lift coefficient and wing area.

Which of these statements about weight or mass is correct ?

Question 224-22 : Weight is a force the weight of an object is independent of the acceleration due to gravity the mass of an object depends on the acceleration due to gravity mass = weight * volume

exemple 408 Weight is a force.Weight is a force.

The induced angle of attack is ?

Question 224-23 : The angle by which the relative airflow is deflected due to downwash the angle between the local flow at the wing and the horizontal tail the angle by which the flow over the wing is deflected when landing flaps are set caused by the fuselage and is greatest at the wing root

.the angle between the chord line and effective airflow is the effective angle of attack the angle between effective airflow and the horizontal flow that was the relative airflow is called the induced angle of attack which is equal to the downwash angle exemple 412 The angle by which the relative airflow is deflected due to downwash.The angle by which the relative airflow is deflected due to downwash.

When an aeroplane enters ground effect ?

Question 224-24 : The lift is increased and the drag is decreased the effective angle of attack is decreased the induced angle of attack is increased drag and lift are reduced

exemple 416 The lift is increased and the drag is decreased.The lift is increased and the drag is decreased.

Which of these statements about weight or mass is correct ?

Question 224-25 : The mass of a body can be determined by dividing its weight by the acceleration due to gravity the mass of a body can be determined by multiplying its weight by the acceleration due to gravity the weight of a body can be determined by dividing its mass by the acceleration due to gravity the weight of a body can be determined by dividing the acceleration due to gravity by its mass

exemple 420 The mass of a body can be determined by dividing its weight by the acceleration due to gravity.The mass of a body can be determined by dividing its weight by the acceleration due to gravity.

Which of these statements about weight or mass is correct ?

Question 224-26 : The weight of a body can be determined by multiplying its mass by the acceleration due to gravity the mass of a body can be determined by multiplying its weight by the acceleration due to gravity the weight of a body can be determined by dividing its mass by the acceleration due to gravity the weight of a body can be determined by dividing the acceleration due to gravity by its mass

exemple 424 The weight of a body can be determined by multiplying its mass by the acceleration due to gravity.The weight of a body can be determined by multiplying its mass by the acceleration due to gravity.

From a polar curve of the entire aeroplane one can read ?

Question 224-27 : The maximum cl/cd ratio and maximum lift coefficient the minimum drag and the maximum lift the minimum drag coefficient and the maximum lift the minimum cl/cd ratio and the minimum drag

exemple 428 The maximum cl/cd ratio and maximum lift coefficient.The maximum cl/cd ratio and maximum lift coefficient.

The diagram shows the parameter x versus tas if a horizontal flight is ?

Question 224-28 : The coefficient of lift the parasite drag the total drag the lift force

New question cqb 15 august 2011 .this question already exists in the database with answer 'induced drag' .'lift formula .lift = 1/2 rho cl x v² x s..where .'1/2 rho' is dynamic pressure .'cl' is coefficient of lift .'v' is speed in m/s .'s' is wing area .if the speed is increase angle of attack has to be reduced to maintain lift contant coefficient of lift will reduce as the speed increases exemple 432 The coefficient of lift.The coefficient of lift.

The additional increase in drag at mach numbers above the critical mach number ?

Question 224-29 : Wave drag increased angle of attack increased interference drag increased skin friction

exemple 436 Wave drag.Wave drag.

Air passes a normal shock wave which of the following statements is correct ?

Question 224-30 : The static temperature increases the static pressure decreases the static temperature decreases the velocity increases

Img /com en/normal and oblic shock wave jpg. exemple 440 The static temperature increases.The static temperature increases.

The bow wave will first appear at ?

Question 224-31 : A mach number just above m = 1 a mach number just below m = 1 mach 1 the critical mach number

A bow wave is a shock wave that forms when the aircraft is flying at a speed just faster than the speed of sound .the bow wave is so named because it is similar to a wave inwater off the bow of a boat . /com en/com080 41 jpg.the wave is in front of the body exemple 444 A mach number just above m = 1.A mach number just above m = 1.

Two methods to increase the critical mach number are ?

Question 224-32 : Thin aerofoils and sweepback of the wing thin aerofoils and dihedral of the wing positive cambering of the aerofoil and sweepback of the wing thick aerofoils and dihedral of the wing

The critical mach number of an aerofoil is the free stream mach number at which sonic speed m=1 is first reached on the upper surface . /com en/com080 152 jpg. in this example mcrit = 0 72 .on a straight wing aircraft the airflow strikes the wing leading edge at 90° and its full impact produces pressure and lift a wing with sweepback is struck by the same airflow at an angle smaller than 90° this airflow on the swept wing has the effect of persuading the wing into believing that it is flying slower than it really is . /com en/com080 1049b jpg.the effect of increasing angle of sweep is an increase in the critical mach number .furthermore if the aerofoil is thinner the airflow will have to travel less distance over the upper wing surface than on a thicker aerofoil in a same time period the mcrit can be increased since mach 1 will be reached later locally exemple 448 Thin aerofoils and sweepback of the wing.Thin aerofoils and sweepback of the wing.

A commercial jet aeroplane is performing a straight descent at a constant mach ?

Question 224-33 : Vmo vne vd mmo

.vmo is defined as the maximum operating limit velocity vmo is expressed in knots calibrated airspeed kcas while mmo is expressed in mach number the vmo limit is usually associated with operations at lower altitudes and deals with structural loads and flutter the mmo limit is associated with operations at higher altitudes and is usually more concerned with compressibility effects and flutter at lower altitudes structural loads and flutter are of concern at higher altitudes compressibility effects and flutter are of concern .in descent and at low altitude vmo .in climb and at high altitude mmo exemple 452 Vmo.Vmo.

'tuck under' is the ?

Question 224-34 : Tendency to nose down when speed is increased into the transonic flight regime tendency to nose up when speed is increased into the transonic flight regime shaking of the control column at high mach number tendency to nose down when the control column is pulled back

Img /com en/com080 418 jpg. exemple 456 Tendency to nose down when speed is increased into the transonic flight regime.Tendency to nose down when speed is increased into the transonic flight regime.

'tuck under' may happen at ?

Question 224-35 : High mach numbers low mach numbers all mach numbers only at low altitudes

.'tuck under' is the tendency to nose down when speed is increased into the transonic flight regime it may happen at high mach numbers when the center of pressure moves rearward . /com en/com080 418 jpg. exemple 460 High mach numbers.High mach numbers.

Which of these statements about 'tuck under' are correct or incorrect . i 'tuck ?

Question 224-36 : I is correct ii is correct i is correct ii is incorrect i is incorrect ii is correct i is incorrect ii is incorrect

.'tuck under' is the tendency to nose down when speed is increased into the transonic flight regime . /com en/com080 418 jpg.'tuck under' or mach tuck is caused principally by two basic factors . 1 shock wave induced flow separation which normally begins near the wing root causes a decrease in the downwash velocity over the elevator and produces a tendency for the aircraft to nose down . 2 aftward movement of the center of pressure which tends to unbalance the equilibrium of the aircraft in relation to its center of gravity cg in subsonic flight exemple 464 I is correct, ii is correct.I is correct, ii is correct.

An a 310 aeroplane weighing 100 tons is turning at fl 350 at constant altitude ?

Question 224-37 : M= 0 69 to m higher than 0 84 m= 0 65 to m higher than 0 84 m= 0 74 to m= 0 84 m= 0 72 to m higher than 0 84

. /com en/com080 100 jpg.

With increasing altitude and constant ias the static lateral stability 1 and ?

Question 224-38 : 1 increase 2 decrease 1 increase 2 increase 1 decrease 2 decrease 1 decrease 2 increase

.first statement .static stability refers to the initial tendency or direction of movement back to equilibrium in aviation it refers to the aircraft's initial response when disturbed from a given aoa slip or bank ..use the very simple 'ertm' diagram ertm for e as/ r as rectified air speed or cas / t as/ m ach . /com en/com080 103a jpg.the ias eas line is vertical because the question states increasing altitude and constant ias .what can we see .tas increase with altitude at constant ias .so the dihedral effect will roll the wings level faster with a faster tas .dihedral effect . /com en/com080 103b jpg.roll moment tends to returne wing to level condition .second statement .dynamic stability refers to the aircraft response over time when disturbed from a given aoa slip or bank .when turbulence or rudder application causes the aircraft to yaw to one side the right wing presents a longer leading edge perpendicular to the relative airflow the airspeed of the right wing increases and it acquires more drag than the left wing the additional drag on the right wing pulls it back turning the aircraft back to its original path .but the roll rate to level the wings will also increased with an increasing tas the cycle is repeated .so swept back wing will decrease the dynamic lateral/directional stability exemple 472 (1) increase (2) decrease.(1) increase (2) decrease.

A jet transport aeroplane is in a straight climb at a constant ias and constant ?

Question 224-39 : Mmo vmo va md

.vmo/mmo is defined as the maximum operating limit speed vmo is expressed in knots calibrated airspeed kcas while mmo is expressed in mach number the vmo limit is usually associated with operations at lower altitudes and deals with structural loads and flutter the mmo limit is associated with operations at higher altitudes and is usually more concerned with compressibility effects and flutter at lower altitudes structural loads and flutter are of concern at higher altitudes compressibility effects and flutter are of concern .in descent and at low altitude vmo .in climb and at high altitude mmo exemple 476 Mmo.Mmo.

What data may be obtained from the buffet onset boundary chart ?

Question 224-40 : The values of the mach number at which low speed and mach buffet occur at different weights and altitudes the values of mmo at different weights and altitudes the values of mcrit at different weights and altitudes the values of the mach number at which low speed and shock stall occur at different weights and altitudes

.here is a buffet boundary graph for an a330 . /com en/com080 151 jpg. exemple 480 The values of the mach number at which low speed and mach buffet occur at different weights and altitudes.The values of the mach number at which low speed and mach buffet occur at different weights and altitudes.

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