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

Question 223-1 : I is incorrect ii is incorrect i is incorrect ii is correct i is correct ii is correct i is correct ii is incorrect

exemple 323 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 I is incorrect, ii is incorrect.

Which of these statements about the effect of wing sweep on centre of pressure ?

Question 223-2 : 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 327 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 stall .swept 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 en/com080 27 jpg.stall 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 I is correct, ii is correct.

Considering subsonic incompressible airflow through a venturi which statement ?

Question 223-3 : 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 331 I is correct, ii is correct. — Img /com en/com080 815 jpg.static pressure decreases in a venturi and airflow speed increases I is correct, ii is correct.

Which statement about an aeroplane leaving ground effect at constant angle of ?

Question 223-4 : I is correct ii is correct i is incorrect ii is incorrect i is correct ii is incorrect i is incorrect ii is correct

exemple 335 I is correct, ii is correct. — .ground effect changes airflow . /com en/com080 821 jpg.when leaving the ground effect the lift coefficient cl decreases it requires an increase in angle of attack to maintain the same cl .the induced angle increases so the induced drag coefficient cdi increases I is correct, ii is correct.

Which statement about an aeroplane entering ground effect is correct .i the ?

Question 223-5 : I is correct ii is correct i is incorrect ii is incorrect i is correct ii is incorrect i is incorrect ii is correct

exemple 339 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 question states entering ground effect at constant angle of attack the lift coefficient cl increases .when entering ground effect induce flow reduces and the induced angle of attack decreases thus the induced drag coefficient cdi decreases I is correct, ii is correct.

Which of these statements about induced drag are correct or incorrect .i ?

Question 223-6 : 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 343 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 increase .induced drag decreases with decreasing aeroplane mass if less lift has to be produced less induced drag will be generated I is correct, ii is correct.

The parameters that can be read from the aeroplane parabolic polar curve are the ?

Question 223-7 : Minimum glide angle and the parasite drag coefficient minimum rate of descent and the induced drag induced drag and the parasite drag aspect ratio of the wing and the induced drag coefficient

exemple 347 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 en/com080 1264 jpg.where 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 only .angle of glide is cl/cd the lift/drag ratio if the lift/drag ratio is 10 1 then the glide angle is 1 in 10 the tangent to the curve from the cl/cd origin shows the best cl/cd 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 diagram .the 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 Minimum glide angle and the parasite drag coefficient.

For most jet transport aeroplanes slat extension has ?

Question 223-8 : A greater effect on stall speed than flap extension the same significant effect on stall speed as flap extension a minor effect on stall speed whereas flap extension has a significant effect the same minor effect on stall speed as flap extension

exemple 351 A greater effect on stall speed than flap extension. — A greater effect on stall speed than flap extension.

One advantage of mounting the horizontal tailplane on top of the vertical fin is ?

Question 223-9 : To improve the aerodynamic efficiency of the vertical fin to decrease the susceptibility to deep stall that it does not require a de icing system to decrease fuel consumption by creating a tail heavy situation

exemple 355 To improve the aerodynamic efficiency of the vertical fin. — To improve the aerodynamic efficiency of the vertical fin.

Which drag components make up parasite drag .1 pressure drag.2 friction ?

Question 223-10 : 1 2 4 1 2 3 4 2 3 4 1 3 4

The transition point is where the boundary layer changes from ?

Question 223-11 : Laminar into turbulent turbulent into laminar attached flow into separated flow separated flow into attached flow

exemple 363 Laminar into turbulent. — Laminar into turbulent.

As angle of attack is increased on a conventional low speed aerofoil at low ?

Question 223-12 : Upper surface near the trailing edge upper surface near the leading edge lower surface near the trailing edge lower surface near the leading edge

exemple 367 Upper surface near the trailing edge. — Upper surface near the trailing edge.

Assuming no flow separation when speed is decreased in straight and level ?

Question 223-13 : 1 moves forward and 2 remains constant 1 moves forward and 2 decreases 1 moves aft and 2 remains constant 1 moves aft and 2 increases

exemple 371 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 pressure .all of them can be represented by a single vector acting at a particular point called the centre of pressure . 669.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 1 moves forward and 2 remains constant.

Given the following characteristic points on a jet engine aeroplane's polar ?

Question 223-14 : 2 5 3 4 1 1 2 4 3 5 3 2 5 1 4 4 5 2 3 1

exemple 375 2, 5, 3, 4, 1. — .the aerofoil polar is a graph of the relation between the lift coefficient and the drag coefficient . /com en/com080 918 jpg. 2, 5, 3, 4, 1.

Assuming standard atmospheric conditions in order to generate the same amount ?

Question 223-15 : A higher tas for any given angle of attack a lower tas and a lower angle of attack a lower tas for any given angle of attack the same tas regardless of angle of attack

exemple 379 A higher tas for any given angle of attack. — A higher tas for any given angle of attack.

In comparison to a conventional aerofoil section typical shape characteristics ?

Question 223-16 : A larger nose radius flatter upper surface and negative as well as positive camber a sharper pointed nose negative camber and a flatter upper surface a larger nose radius flatter lower surface and negative as well as positive camber a sharper pointed nose flatter lower surface and positive camber at the rear of the aerofoil section

exemple 383 A larger nose radius, flatter upper surface and negative as well as positive camber. — . /com en/com080 958 jpg. A larger nose radius, flatter upper surface and negative as well as positive camber.

Induced drag is the result of ?

Question 223-17 : Downwash generated by tip vortices aerodynamic interaction between aeroplane parts boundary layer separation on the aft portion of the wing propeller slipstream over the wing

exemple 387 Downwash generated by tip vortices. — Downwash generated by tip vortices.

Given an aeroplane in steady straight and level flight at low speed and ?

Question 223-18 : Forward cg and idle thrust forward cg and take off thrust aft cg and take off thrust aft cg and idle thrust

exemple 391 Forward cg and idle thrust. — Img683.with 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 value .this 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 Forward cg and idle thrust.

The main function of a trailing edge flap is to ?

Question 223-19 : Increase the maximum lift coefficient of the wing alter the position of the centre of gravity trim the aeroplane longitudinally increase the angle of attack at which a wing will stall

exemple 395 Increase the maximum lift coefficient of the wing. — Increase the maximum lift coefficient of the wing.

Stall speed ias varies with ?

Question 223-20 : Weight altitude below approximately 10000 ft temperature density

What will happen if a large transport aeroplane slowly decelerates in level ?

Question 223-21 : Stick shaker activation or low speed buffeting an accelerated stall clmax will increase due to shock stall high speed buffet

exemple 403 Stick shaker activation or low speed buffeting. — .the only way to maintain altitude as the aeroplane is slowly decelerated is to slowly and gently increase the angle of attack thereby maintaining 1g flight eventually the aeroplane will either begin to low speed buffet or the stick shaker stall warning device will activate .high speed buffet is related to shock induced airflow separation as the aeroplane is accelerated above mcrit .shock stall is also related to shock induced airflow separation as the aeroplane is accelerated above mcrit .an accelerated stall is when the aeroplane is stalled with a load factor greater than 1 Stick shaker activation or low speed buffeting.

Which of the following increases the maximum duration of a glide ?

Question 223-22 : A decrease in mass an increase in mass a headwind a tailwind

exemple 407 A decrease in mass. — .a headwind will always reduce the glide range and a tailwind will always increase the glide range .as 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 reduced .a decrease in mass will permit to increase the duration of the glide A decrease in mass.

Wing spoilers are deflected symmetrically in flight in order to ?

Question 223-23 : Decelerate the aeroplane and/or increase its rate of descent assist the ailerons in obtaining a higher roll rate prevent aeroplane yaw improve glide performance increase lift /drag ratio

exemple 411 Decelerate the aeroplane and/or 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 drag .if in flight spoilers are deployed while maintaining level flight they decelerate the aeroplane .if in flight spoilers are deployed while descending and maintaining speed they increase its rate of descent . /com en/com080 977 jpg. Decelerate the aeroplane and/or increase its rate of descent.

A positively cambered aerofoil will generate zero lift ?

Question 223-24 : At a negative angle of attack at a positive angle of attack at zero angle of attack it can never generate zero lift

exemple 415 At a negative angle of attack. — Img /com en/com080 878 jpg.a 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 At a negative angle of attack.

The lift coefficient cl versus angle of attack curve of a negatively cambered ?

Question 223-25 : To the right of the origin at the origin to the left of the origin nowhere

exemple 419 To the right of the origin. — . /com en/com080 984 jpg.a 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 regards ..this is normal there is no graph with this question at the exam you need to know the shape of the cl/aoa curve To the right of the origin.

Regarding the lift formula if density doubles lift will ?

Question 223-26 : Also double be 4 times greater halve remain the same

exemple 423 Also double. — 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 density is double lift will also double Also double.

Assuming all bodies have the same cross sectional area and are in motion which ?

Question 223-27 : Body b body a body c body d

exemple 427 Body b. — . /com en/com080 986 jpg. Body b.

When a wing spoiler is extended at constant angle of attack ?

Question 223-28 : Drag increases but lift decreases both drag and lift increase drag increases but lift remains constant both drag and lift decrease

exemple 431 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 traveling .however if the angle of attack is unchanged the aircraft will no longer produce sufficient lift to oppose the weight and therefore the aircraft will descend .right answer drag increases but lift decreases Drag increases but lift decreases.

The point where the single resultant aerodynamic force acts on an aerofoil is ?

Question 223-29 : Centre of pressure centre of gravity neutral point aerodynamic centre

exemple 435 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 pressure .all of them can be represented by a single vector acting at a particular point called the centre of pressure . 669.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 Centre of pressure.

Wing loading is the ratio between ?

Question 223-30 : Aeroplane weight and wing area chord and aeroplane weight aeroplane weight and lift coefficient aeroplane weight and wing span

exemple 439 Aeroplane weight and wing area. — . /com en/com080 992 jpg.wing loading is the number of kilos of aircraft weight supported by each square foot of wing area wing loading is usually expressed as the value when the airplane is at its maximum certified weight so the actual wing loading will vary depending on fuel and payload onboard the airplane at any point .wing loading = 'aircraft weight' divided by 'wing area' Aeroplane weight and wing area.

Increasing the aspect ratio of a wing ?

Question 223-31 : Decreases induced drag decreases gust load increases stall speed increases induced drag

exemple 443 Decreases induced drag. — Decreases induced drag.

What may happen if the 'ultimate load factor' is exceeded ?

Question 223-32 : Structural failure elastic or temporary deformation only no structural failure only plastic or permanent deformation flutter

exemple 447 Structural failure. — Structural failure.

The increase in stall speed ias with increasing altitude is due to ?

Question 223-33 : Compressibility effects exceedance of mcrit an increase in tas the larger angle of attack necessary in lower density air to obtain the same lift as at sea level

exemple 451 Compressibility effects. — .the ias stall speed is considered constant at low altitudes because of the tas stall speed increases due to the decreasing altitude but the ias is almost constant this is because the factor increasing the tas stall speed density also affects the ias speed in the same amount .however at higuer altitudes we consider another factor the compresibility that affects the anemometer and hence increases the reading of ias .resuming the ias stall speed is considered constant at lower altitudes below 10000 ft and increases with altitude at higuer altitudes due to compresibility effects .higher altitude > lower air density + lower air viscosity because of lower temperatures > lower reynolds number > less kinematic energy in the boundary layer to oppose adverse pressure gradients > earlier flow separation > lower clmax and aoacrit > higher stall speed Compressibility effects.

An large jet transport aeroplane has the following four flap positions up take ?

Question 223-34 : Slats from retracted to extended flaps from approach to landing flaps from up to take off flaps from take off to approach

exemple 455 Slats from retracted to extended. — .when trailing edge flaps are deployed from up to take off there will be a comparatively large increase in cl and a small increase in cd but with each successive increase in flap angle the increase in cl coefficient of lift will be less whereas the increase in cd coefficient of drag will be greater ..when considering just trailing edge flaps in isolation it could be said that the greatest increase in clmax will be when the flaps move from up to take off ..data shows that the most efficient trailing edge flap triple slotted fowler flap increases clmax by about 100% but only when fully deployed we can only speculate on the increment in clmax from up to take off ..however when considering just slats in isolation the same data shows the increase in clmax for the slat from retracted to extended is about 60% ..of the four answers offered it can be said that the slats moving from retracted to extended would be the selection that will provide the highest positive contribution to clmax Slats from retracted to extended.

In a straight steady climb the thrust must be ?

Question 223-35 : Greater than the drag because it must also balance a component of weight greater than drag because more lift has to be produced lower than the drag because it is assisted by a component of weight equal to the drag

exemple 459 Greater than the drag because it must also balance a component of weight. — Greater than the drag because it must also balance a component of weight.

Regarding a positively cambered aerofoil section which statement is correct .i ?

Question 223-36 : I is correct and ii is correct i is correct and ii is incorrect i is incorrect and ii is correct i is incorrect and ii is incorrect

exemple 463 I is correct and ii is correct. — . /com en/com080 1030a jpg. /com en/com080 1030b jpg.for a positively cambered aerofoil section the angle of attack has a negative value when the lift coefficient equals zero .example a positively cambered aerofoil section . /com en/com080 909 jpg.in this example lift coeffient = 0 when angle of attack = 4° the angle of attack has a negative and the pitching moment is nose down I is correct and ii is correct.

Regarding a symmetric aerofoil section which statement is correct .i the angle ?

Question 223-37 : I is correct and ii is correct i is correct and ii is incorrect i is incorrect and ii is incorrect i is incorrect and ii is correct

exemple 467 I is correct and ii is correct. — . /com en/com080 687a jpg.a symmetrical aerofoil needs to have a positive pitch to produce lift if the pitching moment is zero the lift is zero I is correct and ii is correct.

Regarding a symmetric aerofoil section which statement is correct .i the angle ?

Question 223-38 : I is incorrect and ii is incorrect i is correct and ii is incorrect i is incorrect and ii is correct i is correct and ii is correct

exemple 471 I is incorrect and ii is incorrect. — . /com en/com080 687a jpg.a symmetrical aerofoil needs to have a positive pitch to produce lift if the pitching moment is zero the lift is zero I is incorrect and ii is incorrect.

Which of these statements about wing sweepback are correct or incorrect .i ?

Question 223-39 : I is correct ii is correct i is correct ii is incorrect i is incorrect ii is correct i is incorrect ii is incorrect

. what is mcrit critical mach number . /com en/com080 1049a jpg.the critical mach number of an aeroplane is the highest speed possible without supersonic flow over the wing . what is sweepback .most of the difficulties of transonic flight are associated with shock wave induced flow separation therefore any means of delaying or alleviating the shock induced separation improves aerodynamic performance one method is wing sweepback sweepback theory is based upon the concept that it is only the component of the airflow perpendicular to the leading edge of the wing that affects pressure distribution and formation of shock waves .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 thus the formation of shock waves is delayed advantages of wing sweep include an increase in critical mach number force divergence mach number and the mach number at which drag rises peaks in other words sweep delays the onset of compressibility effects . what is drag divergence mach number .the drag divergence mach number not to be confused with critical mach number is the mach number at which the aerodynamic drag on an airfoil or airframe begins to increase rapidly as the mach number continues to increase this increase can cause the drag coefficient to rise to more than ten times its low speed value .increasing wing sweepback increases the drag divergence mach number . /com en/com080 1049b jpg.the effect of increasing angle of sweep is an increase in the critical mach number and an increase in the drag divergence mach number

Considering subsonic incompressible airflow through a venturi which statement ?

Question 223-40 : I is correct ii is correct i is correct ii is incorrect i is incorrect ii is correct i is incorrect ii is incorrect

exemple 479 I is correct, ii is correct. — Img /com en/com080 815 jpg.static pressure decreases in a venturi and airflow speed increases I is correct, ii is correct.

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