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Compared with level flight prior to the stall the lift 1 and drag 2 in the ? [ Preparation civilian ]

Question 218-1 : 1 decreases 2 increases 1 decreases 2 decreases 1 increases 2 increases 1 increases 2 decreases

.at the stall the lift coefficient begins to fall but it is still high the angle of attack is still high and therefore induced drag is still high profile drag is rising as the airflow separates and breaks down overall there is a small drop in lift coefficient and a continuing rapid rise in drag coefficient exemple 318 (1) decreases (2) increases.(1) decreases (2) increases.

Entering the stall the centre of pressure of a straight 1 wing and of a ?

Question 218-2 : 1 move aft 2 move forward 1 move aft 2 move aft 1 not move 2 move forward 1 move aft 2 not move

.straight wing .the centre of pressure moves forward when 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 lift of the wing in a forward direction relative to the center of gravity of the airplane causing the nose to pitch up exemple 322 (1) move aft, (2) move forward.(1) move aft, (2) move forward.

Which of the following statements about the spin is correct ?

Question 218-3 : During spin recovery the ailerons should be kept in the neutral position an aeroplane is prone to spin when the stall starts at the wing root in the spin airspeed continuously increases every aeroplane should be designed such that it can never enter a spin

exemple 326 During spin recovery the ailerons should be kept in the neutral position.During spin recovery the ailerons should be kept in the neutral position.

During an normal spin recovery ?

Question 218-4 : The ailerons are held in the neutral position the control stick is moved side ways against the angle of bank the control stick is moved side ways in the direction of the angle of bank the control stick is pulled to the most aft position

exemple 330 The ailerons are held in the neutral position.The ailerons are held in the neutral position.

Which of the following statements about the stall of a straight wing aeroplane ?

Question 218-5 : Just before the stall the aeroplane will be have an increased nose down tendency buffeting is the result of tailplane flow separation the nose down effect is the result of increasing downwash due to flow separation the horizontal tail will stall at a higher speed than the wing

.straight wing .the centre of pressure moves forward when the angle of attack increases until it approaches and exceeds the critical angle of attack then it moves aft just before the stall or at the stall . /com en/com080 111 png.loss of lift is felt ahead of the centre of gravity of the aircraft and the centre of pressure moves rearwards so the nose drops and angle of attack is reduced exemple 334 Just before the stall the aeroplane will be have an increased nose down tendency.Just before the stall the aeroplane will be have an increased nose down tendency.

Which of the following are used as stall warning devices ?

Question 218-6 : Stick shaker and stallstrip angle of attack indicator and speed indicator angle of attack sensor and stallstrip stick shaker and angle of attack indicator

.we are talking about warning devices so 'angle of attack sensor' or 'angle of attack indicator' are not regarded as stall warning devices as they dont give you a warning .if you dont have an eye on the angle of attack indicator you won't know that you are approaching the stall . /com en/com080 112 jpg.stallstrips exemple 338 Stick shaker and stallstrip.Stick shaker and stallstrip.

Which combination of design features is known to be responsible for deep stall ?

Question 218-7 : Swept back wings and a t tail straight wings and a t tail swept back wings and wing mounted engines straight wings and aft fuselage mounted engines

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 . /com en/com080 810 jpg.it is a characteristic of t tail aircraft to pitch up viciously when stalled in extreme nose high attitudes making recovery difficult or violent .the tailplane and elevator are in the path of the separated airflow from the wing .it must be emphasised that 'pitch up' is the primary cause of deep stall and a t tail is a contributory factor exemple 342 Swept back wings and a t-tail.Swept back wings and a t-tail.

When a strongly swept back wing stalls and the wake of the wing contacts the ?

Question 218-8 : Nose up tendency and/or lack of elevator response tendency to increase speed after initial stall nose down tendency increase sensitivity of elevator inputs

exemple 346 Nose up tendency and/or lack of elevator response.Nose up tendency and/or lack of elevator response.

The function of the stick pusher is ?

Question 218-9 : To activate and push the stick forward at or beyond a certain value of angle of attack to activate and push the stick forward prior to stick shaker to vibrate the controls to pull the stick to avoid a high speed stall

.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 exemple 350 To activate and push the stick forward at or beyond a certain value of angle of attack.To activate and push the stick forward at or beyond a certain value of angle of attack.

On a wing fitted with a 'fowler' type trailing edge flap the 'full extended' ?

Question 218-10 : An increase in wing area and camber an unaffected wing area and increase in camber an unaffected cd at a given angle of attack an increase in wing area only

exemple 354 An increase in wing area and camber.An increase in wing area and camber.

When flaps are extended whilst maintaining straight and level flight at ?

Question 218-11 : Remain the same increase decrease first increase and then decrease

Lift coefficient can be changed either by changing angle of attack or by changing the camber as the question states maintaining straight and level flight at constant ias then you have to generate the same lift so lift coefficient must stay constant .lowering the flaps will increase the camber and for fowler flaps the wing area as well so the lift coefficient will increase .to maintain lift coefficient constant you will have to reduce the angle of attack exemple 358 Remain the same.Remain the same.

When flaps are deployed at constant angle of attack the lift coefficient will ?

Question 218-12 : Increase decrease remain the same vary as the square of ias

.the angle of attack is the angle between the relative airflow and the wing chord when you deploy flaps it will increase camber and the local angle of attack both of which would increase the lift for the same value of dynamic pressure cl will increase exemple 362 Increase.Increase.

Trailing edge flap extension will ?

Question 218-13 : Decrease the critical angle of attack and increase the value of clmax increase the critical angle of attack and increase the value of clmax decrease the critical angle of attack and decrease the value of clmax increase the critical angle of attack and decrease the value of clmax

.trailing edge flap extension increases the camber of a wing and increases the coefficient of lift air flow on the upper surface must follow this increased cambered profil thus airflow separation on the upper surface of the wing will occur earlier the airflow separation will start at a lower angle of attack than for a clean wing .example when the critical angle of attack was 15° for the wing without trailing edge flaps deployed it is now at 10° .and as the coefficient of lift is increased you can fly at a lower speed by producing the same lift since 's' wing surface increases in the lift formula = 1/2 rho s v² cl exemple 366 Decrease the critical angle of attack and increase the value of clmax.Decrease the critical angle of attack and increase the value of clmax.

Which of the following statements about the difference between krueger flaps ?

Question 218-14 : Deploying a slat will form a slot deploying a krueger flap does not deploying a krueger flap will form a slot deploying a slat does not deploying a slat will increase critical angle of attack deploying a krueger flap does not deploying a krueger flap will increase critical angle of attack deploying a slat does not

Img /com en/com080 123 jpg. exemple 370 Deploying a slat will form a slot, deploying a krueger flap does not.Deploying a slat will form a slot, deploying a krueger flap does not.

What is the most effective flap system ?

Question 218-15 : Fowler flap split flap plain flap single slotted flap

. /com en/com080 124 jpg.a fowler flap move aft then turn down it significantly increases the camber and the wing area exemple 374 Fowler flap.Fowler flap.

Deploying a fowler flap the flap will ?

Question 218-16 : Move aft then turn down turn down then move aft just move aft just turn down

. /com en/com080 125 gif. exemple 378 Move aft, then turn down.Move aft, then turn down.

A slotted flap will increase the clmax by ?

Question 218-17 : Increasing the camber of the aerofoil and re energising the airflow decreasing the skin friction increasing only the camber of the aerofoil increasing the critical angle of attack

exemple 382 Increasing the camber of the aerofoil and re-energising the airflow.Increasing the camber of the aerofoil and re-energising the airflow.

In order to maintain straight and level flight at a constant airspeed whilst ?

Question 218-18 : Increased held constant increased or decreased depending on type of flap decreased

.when you retract the flaps surface wing is reduced .in order to maintain straight and level flight at a constant airspeed you must increase the coefficient of lift cl in the lift formula .lift = cl x 1/2 rho v² x s..cl = lift coefficient.rho = density.v = tas in m/s .s = surface.to increase cl you must increase the angle of attack exemple 386 Increased.Increased.

The function of the slot between an extended slat and the leading edge of the ?

Question 218-19 : Cause a venturi effect which energizes the boundary layer allow space for vibration of the slat reduce the wing loading slow the air flow in the slot so that more pressure is created under the wing

.the function of the slot is to accelerate the flow close to the upper skin retarding the de attachment along the chord . /com en/com080 993 jpg.it is kind of a nozzle that works with the rest of the wing when deployed exemple 390 Cause a venturi effect which energizes the boundary layer.Cause a venturi effect which energizes the boundary layer.

An aeroplane has the following flap settings 0° 15° 30° and 45° slats can ?

Question 218-20 : Flaps from 30° to 45° the slats flaps from 0° to 15° flaps from 15° to 30°

.lowering flap increases both the lift and the drag but not in the same proportion although the lift is the larger force the proportional increase in the drag is greater and so the maximum obtainable lift/drag ratio decreases .the flaps angle from 30° to 45° regarding to the free airflow offers a larger surface thus the parasite drag will be more increased exemple 394 Flaps from 30° to 45°.Flaps from 30° to 45°.

After take off the slats when installed are always retracted later than the ?

Question 218-21 : Because slats extended gives a large decrease in stall speed with relatively less drag because slats extended provides a better view from the cockpit than flaps extended because vmca with slats extended is more favourable compared with the flaps extended situation because flaps extended gives a large decrease in stall speed with relatively less drag

exemple 398 Because slats extended gives a large decrease in stall speed with relatively less drag.Because slats extended gives a large decrease in stall speed with relatively less drag.

Upon extension of a spoiler on a wing ?

Question 218-22 : Cd is increased and cl is decreased only cl is decreased cd remains unaffected both cl and cd are increased cd is increased while cl remains unaffected

.spoilers creates a burbling flow over the wing to destroy lift when you extend a spoiler the coefficient of drag cd is increased and the coefficient of lift cl is decreased .take care if the question states speed and load factor remain constant and the aircraft remains in straight and level flight it means that the reduction in lift is recovered by increasing the angle of attack and thrust thus in this case cl remains unaffected exemple 402 Cd is increased and cl is decreased.Cd is increased and cl is decreased.

When 'spoilers' are used as speed brakes ?

Question 218-23 : At same angle of attack cd is increased and cl is decreased clmax of the polar curve is not affected they do not affect wheel braking action during landing at same angle of attack cl remains unaffected

exemple 406 At same angle of attack, cd is increased and cl is decreased.At same angle of attack, cd is increased and cl is decreased.

How does stall speed ias vary with altitude ?

Question 218-24 : It remains constant at lower altitudes but increases at higher altitudes due to compressibility effects it remains constant it increases with increasing altitude because the density decreases it remains constant at lower altitudes but decreases at higher altitudes due to 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 exemple 410 It remains constant at lower altitudes but increases at higher altitudes due to compressibility effects.It remains constant at lower altitudes but increases at higher altitudes due to compressibility effects.

The type of stall that has the largest associated angle of attack is ?

Question 218-25 : A deep stall a shock stall an accelerated stall a low speed stall

.as an aircraft enters a deep stall the 'pitch up' tendency increases the angle of attack to a very high value and the aircraft also starts to sink which further increases the angle of attack . /com en/com080 810 jpg.the tailplane and elevator are in the path of the separated airflow from the wing .it must be emphasised that 'pitch up' is the primary cause of deep stall and a t tail is a contributory factor exemple 414 A deep stall.A deep stall.

Vortex generators on the upper side of the wing ?

Question 218-26 : Decrease wave drag increase wave drag increase critical mach number decrease critical mach number

.vortex generators decrease shock wave induced flow separation by transfer energy from the free airflow into the boundary layer .the advantage of wing devices that create vortices is that a vortex adds energy to the airflow and increases its forward momentum this momentum encourages the airflow to remain attached to the surface of the wing at higher angles of attack than it would otherwise as a result the wing is able to continue generating lift in conditions where it would have stalled this behavior is particularly advantageous on high performance military aircraft that need to be extremely maneuverable at high angles of attack in combat the advantage for commercial airliners is increased safety since the plane is less likely to experience a wing stall during critical stages of flight like takeoff and landing . /com en/com080 162 jpg. exemple 418 Decrease wave drag.Decrease wave drag.

The high lift device shown in the figure is a . err a 081 181 ?

Question 218-27 : Slat krueger flap fowler flap slotted flap

. /com en/com080 182 jpg. exemple 422 Slat.Slat.

The high lift device shown in the figure below is a . err a 081 182 ?

Question 218-28 : Krueger flap slot or slat fowler flap slotted flap

. /com en/com080 182 jpg. exemple 426 Krueger flap.Krueger flap.

A plain flap will increase clmax by ?

Question 218-29 : Increasing the camber of the aerofoil increasing angle of attack boundary layer control centre of lift movement

exemple 430 Increasing the camber of the aerofoil.Increasing the camber of the aerofoil.

The frontal area of a body placed in a certain airstream is increased by a ?

Question 218-30 : 3 9 6 1 5

. drag formula .d = 1/2 x rho x v² x s x cd.if 's' frontal area = surface is increased by a factor 3 drag d will increase with a factor 3 exemple 434 3.3.

The aerodynamic drag of a body placed in a certain airstream depends amongst ?

Question 218-31 : The airstream velocity the specific mass of the body the weight of the body the cg location of the body

.the drag formula is drag = cd 1/2 rho v² s.where cd = drag coefficient.rho = density.v = tas airstream velocity in m/s .s = surface.there is no reference to the cg location the weight or the specific mass of the body exemple 438 The airstream velocity.The airstream velocity.

A body is placed in a certain airstream the airstream velocity increases by a ?

Question 218-32 : 16 4 8 12

.the drag d formula is d = cd 1/2 rho v² s.where cd = drag coefficient.rho = density.v = tas in m/s .s = surface.if v is increases by a factor 4 drag will increase with a factor 16 4² exemple 442 16.16.

A body is placed in a certain airstream the density of the airstream decreases ?

Question 218-33 : 2 4 8 1 4

.the drag d formula is d = cd 1/2 rho v² s.where cd = drag coefficient.rho = density.v = tas in m/s .s = surface.if rho is divide by 2 drag will decrease with a factor 2 exemple 446 2.2.

The point where the aerodynamic lift acts on a wing is ?

Question 218-34 : The centre of pressure the cg location the point of maximum thickness of the wing the suction point of the wing

.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 exemple 450 The centre of pressure.The centre of pressure.

The location of the centre of pressure of a positively cambered aerofoil ?

Question 218-35 : Shift forward not shift shift aft shift in spanwise direction

.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 exemple 454 Shift forward.Shift forward.

The si unit of measurement for density is ?

Question 218-36 : Kg/m³ psi kg/cm² bar

exemple 458 Kg/m³.Kg/m³.

The unit of measurement of pressure is ?

Question 218-37 : Psi kg/dm² kg/m³ lb/gal

exemple 462 PsiPsi

A laminar boundary layer is a layer in which ?

Question 218-38 : No velocity components exist normal to the surface the vortices are weak the velocity is constant the temperature varies constantly

.'vertical axis' is also call 'normal axis' by 'normal' they mean 'perpendicular to the wing surface' .the airflow in the laminar boundary layer is parallel to the wing surface in a horizontal direction and hence there are no flows perpendicular to the surface exemple 466 No velocity components exist, normal to the surface.No velocity components exist, normal to the surface.

The subsonic static pressure ?

Question 218-39 : Decreases in a flow in a tube when the diameter decreases is the total pressure plus the dynamic pressure is the pressure in a point at which the velocity has become zero increases in a flow in a tube when the diameter decreases

The lift and drag forces acting on a wing cross section ?

Question 218-40 : Depend on the pressure distribution about the wing cross section are normal to each other at just one angle of attack are proportional to each other independent of angle of attack vary linearly with the angle of attack

.the distribution of velocities with resulting pressure distribution is determined by the shape or profile of the surface and the angle of attack cl or cd .the aerodynamic force of lift results from the pressure differential between the top and bottom surfaces of the wing .drag is the product of dynamic pressure drag coefficient and surface area exemple 474 Depend on the pressure distribution about the wing cross section.Depend on the pressure distribution about the wing cross section.

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