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Question 235-1 : The difference between the effects of slat and flap asymmetry is that . 'large' in the context of this question means not or hardly controllable by normal use of controls ? [ Formation assignment ]

Flap asymmetry causes a large rolling moment at any speed whereas slat asymmetry causes a large difference in clmax

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 335 Flap asymmetry causes a large rolling moment at any speed whereas slat asymmetry causes a large difference in clmax.

Question 235-2 : The airload on the horizontal tailplane tailload of an aeroplane in straight and level cruise flight ?

Is in general directed downwards and will become less negative when the c g moves aft

.when the cg is ahead of the center of pressure the balance of lift and weight will be pushing the nose down to keep level you need a tail moment pushing the tail down . /com en/com080 560 jpg.with an aft cg the downward force on the horizontal tailplane can be reduced the lift is also reduced to keep the balance of lift and total weight constant exemple 339 Is in general directed downwards and will become less negative when the c.g. moves aft.

Question 235-3 : The boundary layer of a wing is ?

A layer on the wing in which the stream velocity is lower than the free stream velocity

.the boundary layer thickness describes the distance above the wing where the velocity of the airflow goes from zero at the surface to near 99% free stream velocity .free stream velocity is the airflow far away from the influences of the airfoil it's the undisturbed airflow .the boundary layer can be either laminar or turbulent exemple 343 A layer on the wing in which the stream velocity is lower than the free stream velocity.

Question 235-4 : If the aspect ratio of a wing increases whilst all other relevant factors remain constant the critical angle of attack will ?

Decrease

.the aspect ratio of a wing is the relationship between its length and width or span and chord actually the square of the span divided by the wing area .you could have two aerofoils of equal surface area but different aspect ratios depending on what they were designed for .the higher the aspect ratio of length to width the more lift you get with less induced drag at the tips .but the wing's aspect ratio ar also affects the overall lift coefficient of the wing . /com en/com080 570 jpg.for a given reynolds number the wing with higher aspect ratio with long wingspan and small chord reaches higher lift coefficient but stalls at a lower angle of attack than the wing with low aspect ratio exemple 347 Decrease.

Question 235-5 : On a large transport aeroplane the auto slat system ?

Extends the slats automatically when a certain value of angle of attack is exceeded

.the autoslat system is designed to enhance airplane stall characteristics at high angles of attack during takeoff or approach to landing .as the airplane approaches.the stall angle the slats automatically begin driving to the full extended position prior to stick shaker activation the slats return to the up or extend position when the pitch angle is sufficiently reduced below the stall critical attitude exemple 351 Extends the slats automatically when a certain value of angle of attack is exceeded.

Question 235-6 : How does the total drag change in straight and level flight at constant mass as speed is increased from the stall speed vs to maximum ias vne or vmo ?

Initially decreases then increases

. /com en/com032 209 jpg. exemple 355 Initially decreases, then increases.

Question 235-7 : How is stall warning presented to the pilots of a large transport aeroplane ?

Stick shaker and/or aerodynamic buffet

.artificial stall warning on small aircraft is usually given by a buzzer or horn the artificial stall warning device used on modern large aircraft is a stick shaker in conjunction with lights and a noise maker .separated airflow prior to a low speed stall can cause airframe buffet aerodynamic buffet is a valuable stall warning .if the pilots do not react you can find an 'alpha floor protection' system .'alpha floor protection' is a system designed to prevent an aircraft from reaching very near its critical angle of attack because of slowing down too much the system automatically increases the thrust of the aircraft when speed is predicted to reach or exceed the critical angle of attack often found on newer generations of commercial aircraft such as the airbus 320 330 340 380 and boeing 777 exemple 359 Stick shaker and/or aerodynamic buffet.

Question 235-8 : Load factor is ?

Lift/weight

exemple 363 Lift/weight.

Question 235-9 : In order to perform a steady level turn at constant speed in an aeroplane the pilot must ?

Increase thrust/power and angle of attack

.in order to perform a steady level turn at constant speed in an aeroplane the pilot must increase thrust/power and angle of attack there is a constant rate of change of direction and the force acting on the machine are equilibrium some of the lift force is applied to the turn so the lift vector is reduced . /com en/com080 590 jpg.as you make turn the original lift vector has to be split as a side element is added to pull you into turn .the side element is centripetal force acting towards the center of the turn total lift is the resultant of them both the diagonal line and you can see that the vertical lift vector has reduced and needs some compensation to maintain the lift or the aircraft will descend .you must increase the angle of attack to increase lift it will cost some speed if you not increase thrust/power exemple 367 Increase thrust/power and angle of attack.

Question 235-10 : Minimum drag of an aeroplane in straight and level flight occurs at the ?

Maximum cl/cd ratio

.we are in level flight not in descent we must produce lift .with the higher cl/cd ratio we will produce the minimum drag in level flight exemple 371 Maximum cl/cd ratio.

Question 235-11 : Lift is the ?

Component of the total aerodynamic force perpendicular to the local flow

. /com en/com080 604 jpg.lift is the upward force created by the wings moving through the air that sustains the airplane in flight lift operates to overcome weight it must be equal to or greater than the weight of the object in flight and acting in the opposite direction .lift can be increased by increasing the forward speed of the aircraft or by increasing the angle of attack exemple 375 Component of the total aerodynamic force, perpendicular to the local flow.

Question 235-12 : The stick shaker stalling is taken from ?

Ias

exemple 379 Ias

Question 235-13 : Low speed pitch up is caused by the ?

Outward drift of the boundary layer on a swept back wing

.flying at low speed means flying at high angle of attack 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 en/com080 27 jpg.stall 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 exemple 383 Outward drift of the boundary layer on a swept-back wing.

Question 235-14 : Which statement is correct .i stall speeds are determined with the cg at the aft limit .ii minimum control speeds are determined with the cg at the forward limit ?

I is incorrect ii is incorrect

.vso and vs1 are the stalling speeds or the minimum steady flight speed cas at which the aeroplane is controllable with . 1 for reciprocating engine powered aeroplanes engine s idling the throttle s closed or at not more than the power necessary for zero thrust at a speed not more than 110% of the stalling speed and. 2 for turbine engine powered aeroplanes the propulsive thrust may not be greater than zero at the stalling speed or if the resultant thrust has no appreciable effect on the stalling speed with engine s idling and throttle s closed . 3 propeller s in the take off position . 4 the aeroplane in the condition existing in the test in which vso and vs1 are being used . 5 centre of gravity in the position which results in the highest value of vso and vs1 and. 6 weight used when vso or vs1 are being used as a factor to determine compliance with a required performance standard ..vmc must be established with . 1 the aeroplane in each take off configuration or at the option of the applicant in the most critical take off configuration . 2 maximum available take off power or thrust on the operating engines . 3 the most unfavourable centre of gravity . 4 the aeroplane trimmed for takeoff and. 5 the most unfavourable weight in the range of take off weights exemple 387 I is incorrect, ii is incorrect.

Question 235-15 : In a steady co ordinated horizontal turn lift is ?

Greater than in straight and level flight because it must balance the weight and generate the centripetal force

. /com en/com080 623 gif.centripetal force is the force in the direction of the center of the turn exemple 391 Greater than in straight and level flight, because it must balance the weight and generate the centripetal force.

Question 235-16 : The span wise flow is caused by the difference between the air pressure on top and beneath the wing and its direction of movement goes from ?

Beneath to the top of the wing via the wing tip

. /com en/com080 459 jpg.the spanwise flow goes from beneath to the top of the wing via the wing tip exemple 395 Beneath to the top of the wing via the wing tip.

Question 235-17 : Amongst the following factors which will decrease the ground distance covered during a glide assume zero power/thrust ?

Headwind

. /com en/com080 642 jpg.the wind and lift/drag ratio determine the distance travelled over the ground of an aeroplane in a glide lift/drag ratio changes with angle of attack not with the mass exemple 399 Headwind.

Question 235-18 : When speed is increased in straight and level flight on a positively cambered aerofoil what happens to the . 1 centre of pressure and . 2 the magnitude of the total lift force ?

1 moves aft 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 pressure .all of them can be represented by a single vector acting at a particular point called the centre of pressure . /com en/com080 686 jpg.the centre of pressure is a theoretical point on the chord line through which the resultant of all forces the total reaction is said to act .its 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 cg .thus 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 exemple 403 1 moves aft and 2 remains constant.

Question 235-19 : The lift coefficient cl versus angle of attack curve of a symmetrical aerofoil section intersects the vertical axis of the graph ?

At the origin

. /com en/com080 687a jpg. /com en/com080 687 jpg.a symmetrical aerofoil section produces lift at positive angle of attack the lift coefficient cl versus angle of attack curve intersects the vertical axis of the graph at the origin exemple 407 At the origin.

Question 235-20 : The lift coefficient cl versus angle of attack curve of a negatively cambered aerofoil section intersects the vertical axis of the graph ?

Below the origin

. /com en/com080 688 jpg.a negatively cambered aerofoil section produces lift at positive angle of attack only in our example at approximately 3° angle of attack .the lift coefficient cl versus angle of attack curve intersects the vertical axis of the graph below the origin exemple 411 Below the origin.

Question 235-21 : The lift coefficient cl versus angle of attack curve of a positively cambered aerofoil section intersects the horizontal axis of the graph ?

To the left of the origin

. /com en/com080 689 jpg.for a positively cambered aerofoil section the curve intersects the horizontal axis of the graph to the left of the origin because for a positively cambered aerofoil section the angle of attack has a negative value when the lift coefficient equals zero exemple 415 To the left of the origin.

Question 235-22 : Which statement is correct .i a stick pusher activates at a higher angle of attack than a stick shaker .ii a stick pusher prevents the pilot from increasing the angle of attack further ?

I is correct ii is correct

A stick pusher activates at a higher angle of attack than a stick shaker .a stick pusher prevents the pilot from increasing the angle of attack further .a 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 sufficiently .vdo927.you 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 activated .a 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 exemple 419 I is correct, ii is correct.

Question 235-23 : Wing sweep angle is the angle between ?

The quarter chord line of the wing and the lateral axis

. /com en/com080 692 jpg. exemple 423 The quarter-chord line of the wing and the lateral axis.

Question 235-24 : Which statement is correct . i stall speeds are determined with the cg at the forward limit . ii minimum control speeds are determined with the cg at the aft limit ?

I is correct ii is correct

.vso and vs1 are the stalling speeds or the minimum steady flight speed cas at which the aeroplane is controllable with . 1 for reciprocating engine powered aeroplanes engine s idling the throttle s closed or at not more than the power necessary for zero thrust at a speed not more than 110% of the stalling speed and. 2 for turbine engine powered aeroplanes the propulsive thrust may not be greater than zero at the stalling speed or if the resultant thrust has no appreciable effect on the stalling speed with engine s idling and throttle s closed . 3 propeller s in the take off position . 4 the aeroplane in the condition existing in the test in which vso and vs1 are being used . 5 centre of gravity in the position which results in the highest value of vso and vs1 and. 6 weight used when vso or vs1 are being used as a factor to determine compliance with a required performance standard ..vmc must be established with . 1 the aeroplane in each take off configuration or at the option of the applicant in the most critical take off configuration . 2 maximum available take off power or thrust on the operating engines . 3 the most unfavourable centre of gravity . 4 the aeroplane trimmed for takeoff and. 5 the most unfavourable weight in the range of take off weights exemple 427 I is correct, ii is correct.

Question 235-25 : An aeroplane's sideslip angle is defined as the angle between the ?

Speed vector and the plane of symmetry

. /com en/com080 717 jpg.a sideslip is defined as the angle between the speed vector and the plane of symmetry it not only produces a rolling moment but also a yawing moment the strength of which is dependent on the magnitude of the directional static stability exemple 431 Speed vector and the plane of symmetry.

Question 235-26 : Which of these statements about boundary layers is correct ?

A laminar boundary layer is thinner than a turbulent one

exemple 435 A laminar boundary layer is thinner than a turbulent one.

Question 235-27 : Which of these statements about boundary layers is correct ?

A turbulent boundary layer produces more friction drag than a laminar one

exemple 439 A turbulent boundary layer produces more friction drag than a laminar one.

Question 235-28 : Which of these statements about weight or mass is correct ?

The weight of an object depends on the acceleration due to gravity

exemple 443 The weight of an object depends on the acceleration due to gravity.

Question 235-29 : Which of these statements about weight or mass is correct ?

The mass of an object is independent of the acceleration due to gravity

exemple 447 The mass of an object is independent of the acceleration due to gravity.

Question 235-30 : Which of these statements about weight or mass is correct ?

In the si system the unit of measurement for mass is the kilogram

exemple 451 In the si system the unit of measurement for mass is the kilogram.

Question 235-31 : The total drag of a three dimensional wing consists of ?

Induced drag and parasite drag

Bcg160 .induced drag is the drag caused by lift generating specially due to the wing tip vortex created due to the tipwhise flow component of lower wing airflow this is why induced drag appers when talking about a 3d wing .parasite drag includes 1 skin frinction drag 2 form pressure drag 3 interference drag .by ansewering induced drag + parasite drag you are including inside skin friction drag form drag interference drag so it is the only answer that is completed exemple 455 Induced drag and parasite drag.

Question 235-32 : Which statement about the effects on drag of fitting external tip tanks to the wings of an aeroplane is correct .i parasite drag increases .ii induced drag increases ?

I is correct ii is incorrect

Admin .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 . 2759. siai marchetti sf 260 with tip tanks exemple 459 I is correct, ii is incorrect.

Question 235-33 : Which statement about the effects on drag of removing external tip tanks from the wings of an aeroplane is correct . i parasite drag increases . ii induced drag increases ?

I is incorrect ii is correct

.the external wing tip tanks act like winglets they reduce the wing tip vortices the induced drag but they increase the parasite drag form drag + skin friction drag exemple 463 I is incorrect, ii is correct.

Question 235-34 : Which statement about an aeroplane entering ground effect at constant angle of attack is correct . i the lift coefficient cl increases . ii the induced drag coefficient cdi decreases ?

I is correct ii is correct

.ground effect changes airflow . /com en/com080 821 jpg.when 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 lift coefficient cl increases on entering ground effect induce flow reduces and the induced angle of attack decreases thus the induced drag coefficient cdi decreases exemple 467 I is correct, ii is correct.

Question 235-35 : The mean geometric chord of a wing is the ?

Wing area divided by the wing span

.mean geometric chord this is the average chord length through a wind found by wing area/wing span . /com en/com080 737 png.the mean geometric chord location is the same for two extreme positions of the root chord exemple 471 Wing area divided by the wing span.

Question 235-36 : Taper ratio of a wing is the ratio between ?

Tip chord and root chord

. /com en/com080 738 jpg.

Question 235-37 : Given an aeroplane in steady straight and level flight at low speed and considering the effects of cg location and thrust the lowest value of wing lift occurs at ?

Aft cg and take off thrust

Img684.with an aft cg the lift on the tail is at a maximum the horizontal stabiliser produces positive lift at low speed the nose is pointing upward and there will be a significant upward thrust to take some of the weight off the wings .this question also appears with the opposite statement at the exam .' the highest value of wing lift occurs at forward cg and idle thrust '. 683 exemple 479 Aft cg and take-off thrust.

Question 235-38 : Assuming isa conditions and no compressibility effects if an aeroplane maintains straight and level flight at the same angle of attack at two different altitudes the ?

Ias at both altitudes is the same

.level flight at the same angle of attack means the same ias .lift formula = cl x 1/2 rho v² x s.cl = lift coefficient.rho = density.v = tas in m/s .s = surface.lift at altitude 1 = lift at altitude 2.they say same angle of attack thus cl is the same surface does not change and there is no compressibility effects .since rho decreases with altitude tas must increase in order to keep rho x v² unchanged exemple 483 Ias at both altitudes is the same.

Question 235-39 : Which of these statements about stall speed is correct ?

Decreasing sweepback decreases stall speed

.anhedral is incorporated into high wing sweptback designs to decrease the lateral stability nothing to do with stall high wing aircraft have powerful stabilising results in sideslip due to fuselage shielding .now swept wings are prone to tip stall which moves the centre of pressure sharply forward combine this with the changing downwash over the tail causes a sharp nose up change of trim so the stall speed is higher if you decrease the sweepback you decrease the stall speed exemple 487 Decreasing sweepback decreases stall speed.

Question 235-40 : Which of these statements about induced drag are correct or incorrect . i an elliptical spanwise lift distribution generates less induced drag than a rectangular lift distribution .ii induced drag increases with decreasing aspect ratio ?

I is correct ii is correct

.the correct statement is an elliptical spanwise lift distribution generates less induced drag than a rectangular lift distribution .both lift distribution and load distribution are of great importance in the wing design process .to give minimum induced drag the span wise efficiency factor e should be as close to 1 as possible this is the case of an elliptic span wise lift distribution a number of methods are available to modify the span wise distribution of lift they include 1 planform taper to obtain an elliptic planform used for the spitfire wing which was remarkably elliptic 2 a geometric twist and/or aerodynamic twist to obtain elliptic lift distribution or 3 a combination of all of these methods .in the past 1930s it was thought that for an elliptic lift distribution the chord must vary elliptically along the span the direct result of such logic was that the wing planform must be elliptical for this reason several aircraft wing planforms such as supermarine spitfire a famous british world war ii fighter were made elliptic but today we know that there are various parameters that make the lift distribution elliptic thus there is no need for the wing planform to be planform an elliptical planform is hard to manufacture and is costly from the point of view of construction the best type of wing is the un tapered untwisted wing .the correct statement is induced drag increases with decreasing aspect ratio .aspect ratio is defined as the square of the wingspan divided by the area of the wing planform . /com en/com080 38 jpg.induced drag varies with lift speed and aspect ratio is inversely proportional to aspect ratio and v² so multiply by 1/v² and directly proportional to lift²/cl²/weight² exemple 491 I is correct, ii is correct.


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