Exam > pilot : What increases the critical angle of attack use of ?

Question 208-1 : Slats flaps spoilers fuselage mounted speed brakes

When considering a swept back wing with no corrective design features at the ?

Question 208-2 : Tip stall will occur first which produces a nose up pitching moment wing root stall will occur first which produces a rolling moment tip stall will occur first which produces a nose down pitching moment leading edge stall will occur first which produces a nose down pitching moment

exemple 312 tip stall will occur first, which produces a nose-up pitching moment. — tip stall will occur first, which produces a nose-up pitching moment.

Which boundary layer when considering its velocity profile perpendicular to the ?

Question 208-3 : Turbulent boundary layer laminar boundary layer no difference the boundary layer in the transition between turbulent and laminar

exemple 316 turbulent boundary layer. — .the boundary layer extends from the surface to near freestream speed think of the surface layer as molecules bouncing slowly along in the turbulent layer they are ripped smartly up to high speed very soon after you leave the surface and then slowly speed up toward freestream over the rest of the layer turbulent boundary layer.

The si unit of measurement for pressure is ?

Question 208-4 : N/m² kg/m³ lb/gal bar/dm²

exemple 320 n/m². — .icao annex 5 units of measurement attachment b . 2 mass force and weight .2 1 the principal departure of si from the gravimetric system of metric engineering units is the use of explicitly distinct units from mass and force in si the name kilogram is restricted to the unit of mass and the kilogram force from which the suffix force was in practice often erroneously dropped is not to be used in its place the si unit of force the newton is used likewise the newton rather than the kilogram force is used to form derived units which include force for example pressure or stress n/m² = pa energy nm = j and power nm/s = w n/m².

The polar curve of an aerofoil section is a graphic relationship between ?

Question 208-5 : Lift coefficient cl and drag coefficient cd tas and stall speed angle of attack and lift coefficient cl drag coefficient cd and angle of attack

exemple 324 lift coefficient cl and drag coefficient cd. — lift coefficient cl and drag coefficient cd.

The speed for minimum glide angle occurs at an angle of attack that corresponds ?

Question 208-6 : Cl/cd max clmax cl/cd² max cl³/cd² max

The value of the induced drag of an aeroplane in straight and level flight at ?

Question 208-7 : 1/v² v² v 1/v

exemple 332 1/v². — .induced drag comes from the air's reaction to the aerofoil or is induced from the creation of lift when air at different pressures mixes at the trailing edge so it comes from lift producing surfaces wings and varies with angle of attack so the slower the aerofoil is moving the more induced drag you will get because you have to shift more air in a shorter distance however if no lift is induced there is no induced drag similary the more lift there is the more induced drag there is it may comes from tip vortices for example and is inversely proportional to the square of the velocity 1/v².

Upon extension of fowler flaps whilst maintaining the same angle of attack ?

Question 208-8 : Cl and cd increase cl increases while cd remains unaffected cd decreases while the centre of lift shifts aft cl decreases while the centre of lift shifts forward

exemple 336 cl and cd increase. — cl and cd increase.

True airspeed tas is ?

Question 208-9 : Lower than the indicated airspeed ias at altitudes below sea level under isa conditions higher than the indicated airspeed ias at altitudes below sea level under isa conditions equal to the ias multiplied by the air density at sea level eas corrected for compressibility

exemple 340 lower than the indicated airspeed (ias) at altitudes below sea level, under isa conditions. — .true air speed tas is obtained from indicated air speed ias by correcting for the following errors instrument position compressibility and density .so tas is greater than ias with increasing altitude as density reduces.for this question they state at altitudes below sea level so it is reverse tas will be lower than ias density is higher for altitude below mean sea level.keep in mind that .ias is proportional to 1/2 rho tas² . rho = density lower than the indicated airspeed (ias) at altitudes below sea level, under isa conditions.

The span wise flow on an unswept wing is from the ?

Question 208-10 : Lower to the upper surface via the wing tip upper surface via the trailing edge to the lower wing surface lower surface via the trailing edge to the upper wing surface upper surface via the leading edge to the lower wing surface

exemple 344 lower to the upper surface via the wing tip. — . /com en/com080 459 jpg..the boundary layer flow is back over the wing and once past the point of maximum camber is moving to an area of higher pressure an adverse pressure gradient lower to the upper surface via the wing tip.

Total pressure is rho = density ?

Question 208-11 : Static pressure plus dynamic pressure static pressure minus dynamic pressure 1/2 rho v² measured at a small hole in a surface parallel to the local stream

exemple 348 static pressure plus dynamic pressure. — static pressure plus dynamic pressure.

The terms 'q' and 's' in the lift formula are ?

Question 208-12 : Dynamic pressure and the area of the wing square root of surface and wing loading static pressure and wing surface area static pressure and dynamic pressure

exemple 352 dynamic pressure and the area of the wing. — .lift formula = 1/2 rho cl x v² x s..where.'q' or '1/2 rho v²' is dynamic pressure rho = density v = speed in m/s.'cl' is coefficient of lift.'s' is wing area dynamic pressure and the area of the wing.

The stall speed ?

Question 208-13 : Increases with an increased weight decreases with an increased weight does not depend on weight increases with the length of the wingspan

exemple 356 increases with an increased weight. — increases with an increased weight.

Trailing edge flaps once extended ?

Question 208-14 : Degrade the best angle of glide increase the zero lift angle of attack significantly increase the angle of attack for maximum lift significantly lower the drag

exemple 360 degrade the best angle of glide. — degrade the best angle of glide.

Which statement concerning the local flow pattern around a wing is correct ?

Question 208-15 : By fitting winglets to the wing tip the strength of the wing tip vortices is reduced which in turn reduces induced drag slat extension at a constant angle of attack and nomal extension speeds will increase the lift coefficient which will also increase the induced drag coefficient sweepback reduces drag since compared with a straight wing of equal area the span increases vortex generators on the wing partially block the spanwise flow over the wing leading to a reduction in induced drag

exemple 364 by fitting winglets to the wing tip, the strength of the wing tip vortices is reduced which in turn reduces induced drag. — by fitting winglets to the wing tip, the strength of the wing tip vortices is reduced which in turn reduces induced drag.

Which statement is correct ?

Question 208-16 : Flap extension causes a reduction in stall speed and the maximum glide distance flap extension will increase cl/cd max thus causing a reduction in the minimum rate of descent flap extension has no influence on the minimum rate of descent as only tas has to be taken into account spoiler extension causes a reduction in stall speed and the minimum rate of descent but increases the minimum descent angle

exemple 368 flap extension causes a reduction in stall speed and the maximum glide distance. — .extension of flaps causes a reduction of the stall speed the maximum glide distance also reduces.stalls occur at the critical angle of attack at which point the airflow over the wing becomes chaotic and the wings can no longer produce sufficient lift to counteract weight .the extension of flaps has the effect of increasing the relative angle of attack of the airfoil but induced drag is also increased .more drag = less gliding distance flap extension causes a reduction in stall speed and the maximum glide distance.

While flying under icing conditions the largest ice build up will occur ?

Question 208-17 : The frontal areas of the aircraft the upper and lower surfaces on the rear of the wing the upper and lower rudder surfaces the pitot and static probes only

exemple 372 the frontal areas of the aircraft. — the frontal areas of the aircraft.

Which statement is correct ?

Question 208-18 : Spoiler extension increases the stallspeed the minimum rate of descent and the minimum angle of descent flap extension reduces the maximum lift/drag ratio thus reducing the minimum rate of descent flap extension reduces the stallspeed which increases the maximum glide distance flap extension has no effect on the minimum rate of descent as this is only affected by tas

exemple 376 spoiler extension increases the stallspeed, the minimum rate of descent and the minimum angle of descent. — .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 spoiler extension increases the stallspeed, the minimum rate of descent and the minimum angle of descent.

Which statement is correct ?

Question 208-19 : As the angle of attack increases the stagnation point on the wing's profile moves downwards the centre of pressure is the point on the wing's leading edge where the airflow splits up the stagnation point is another name for centre of pressure the stagnation point is always situated on the chordline the centre of pressure is not

. /com en/com080 23 jpg..in red the stagnation point will move down compare to the chord line .in blue the point of lowest pressure will move forward exemple 380 as the angle of attack increases, the stagnation point on the wing's profile moves downwards.

as the angle of attack increases, the stagnation point on the wing's profile moves downwards.

During a climbing turn to the right the ?

Question 208-20 : Angle of attack of the left wing is larger than the angle of attack of the right wing angle of attack of the left wing is smaller than the angle of attack of the right wing angle of attack of both wings is the same stall angle of attack of the left wing will be larger than the corresponding angle for the right wing

exemple 384 angle of attack of the left wing is larger than the angle of attack of the right wing. — .when the airplane is established in climb in a right coordinated turn the left wing is faster than the right one .also if a stall occurs while climbing in the same condition the left wing will reach first his max angle of attack the airplane will roll to the left. chikarelly .if the speed of the left wing is higher the angle of attack will be lower..for the left wing to be higher it must generate more lift the down going aileron on the left wing increases angle of attack angle of attack of the left wing is larger than the angle of attack of the right wing.

Dividing lift by weight gives ?

Question 208-21 : Load factor lift drag ratio wing loading aspect ratio

Dangerous stall characteristics in large transport aeroplanes that require ?

Question 208-22 : Excessive wing drop and deep stall pitch down and yaw distinct aerodynamic buffet pitch down and increase in speed

exemple 392 excessive wing drop and deep stall. — .the stick pusher inhibits excessive wing drop and deep stall .at approximately one knot above stall speed pre programmed stick forces automatically move the stick forward preventing the stall from developing excessive wing drop and deep stall.

Bernoulli's law states . note rho is the mean sea level density under isa ?

Question 208-23 : Pstat + 1/2rhov² = constant pstat + 1/2rhoias² = constant pdyn+ 1/2rhov² = constant ptot+ 1/2rhov² = pstat

exemple 396 pstat + 1/2rhov² = constant. — .pt total pressure..ps static pressure..pd dynamic pressure 1/2 x density x tas²..bernoulli's theorem is.pt = ps + pd pstat + 1/2rhov² = constant.

Assuming zero wing twist the wing planform that gives the highest local lift ?

Question 208-24 : Rectangular elliptical tapered swept back

exemple 400 rectangular. — . /com en/com080 496 jpg.. /com en/com080 496a jpg. rectangular.

Given the following aeroplane configurations .1 clean wing .2 slats only ?

Question 208-25 : 3 1 2 1 3 2 2 1 3 2 3 1

exemple 404 3, 1, 2. — .the angle at which the stall occurs is called the critical angle of attack.3 trailing edge flap decrease the critical angle of attack and increase the value of clmax .1 critical angle of attack of a clean wing is higher than a wing with flaps only extended but generate less lift .2 the slat re directs the airflow at the front of the wing allowing it to flow more smoothly over the upper surface while at a high angle of attack this allows the wing to be operated effectively at the higher angles required to produce more lift 3, 1, 2.

Floating due to ground effect during an approach to land will occur ?

Question 208-26 : When the height is less than halve of the length of the wing span above the surface when the height is less than twice the length of the wing span above the surface when a higher than normal angle of attack is used at a speed approaching the stall

exemple 408 when the height is less than halve of the length of the wing span above the surface. — when the height is less than halve of the length of the wing span above the surface.

An aeroplane climbs to cruising level with a constant pitch attitude and ?

Question 208-27 : Gamma decreases angle of attack increases ias decreases gamma decreases angle of attack increases ias remains constant gamma decreases angle of attack remains constant ias decreases gamma remains constant angle of attack remains constant ias decreases

exemple 412 gamma decreases, angle of attack increases, ias decreases. — .your flight path angle gamma will decrease because as you climb the thrust will decrease. 682..if you maintain the same pitch angle angle of attack will increase .and an increase in angle of attack means an increase in drag ias will decrease since we do not have an excess of thrust to counteract this additional drag gamma decreases, angle of attack increases, ias decreases.

An aerofoil is cambered when ?

Question 208-28 : The line which connects the centres of all inscribed circles is curved the chord line is curved the upper surface of the aerofoil is curved the maximum thickness is large compared with the length of the chord

exemple 416 the line, which connects the centres of all inscribed circles, is curved. — . /com en/com080 520 png.the green line is the chord the direct line from leading edge to trailing edge .in red the line which connects the centres of all inscribed circles this line is curved when the aerofoil is cambered the line, which connects the centres of all inscribed circles, is curved.

An aeroplane being manually flown in the speed unstable region experiences a ?

Question 208-29 : Further decrease increase initially increase and thereafter decrease initially further decrease and thereafter increase

exemple 420 further decrease. — . the speed unstable region means the backside of the drag or power curve also called the region of reversed command .in this 'speed unstable region' you control airpseed with elevator and altitude with throttle if a disturbance causes a speed reduction in order to maintain altitude and without ay action on thrust you have to increase lift by increasing angle of attack by pulling the stick or the control column further decrease.

A slat will ?

Question 208-30 : Prolongs the stall to a higher angle of attack increase the camber of the aerofoil and divert the flow around the sharp leading edge increase the lift by increasing the wing area and the camber of the aft portion of the wing provide a boundary layer suction on the upper surface of the wing

exemple 424 prolongs the stall to a higher angle of attack. — .the deployment of a slat increases the maximum coefficient of lift by more than 70% and the stalling angle of attack from 15° to 22° . /com en/com080 524 jpg.a deployed slat will increase the boundary layer energy and increase the suction peak on the fixed part of the wing so that the stall is postponed to higher angles of attack a slat goes not significantly affect the camber of a wing prolongs the stall to a higher angle of attack.

A flat plate when positioned in the airflow at a small angle of attack will ?

Question 208-31 : Both lift and drag lift but no drag drag but no lift neither lift nor drag

exemple 428 both lift and drag. — both lift and drag.

An aeroplane has the following flap positions 0° 15° 30° 45° slats can also ?

Question 208-32 : The slats from the retracted to the take off position the flaps from 30° to 45° the flaps from 0° to 15° the flaps from 15° to 30°

exemple 432 the slats from the retracted to the take-off position. — the slats from the retracted to the take-off position.

An increase in wing loading will ?

Question 208-33 : Increase the stall speed decrease the minimum glide angle increase clmax increase sensitivity to turbulence

exemple 436 increase the stall speed. — .anything that causes an increase in wing loading will also cause an increase in stall speed such as pulling gs turn or flying a loaded aircraft increase the stall speed.

The difference between the effects of slat and flap asymmetry is that . 'large' ?

Question 208-34 : Flap asymmetry causes a large rolling moment at any speed whereas slat asymmetry causes a large difference in clmax flap asymmetry causes a large yawing moment whereas slat asymmetry causes a large rolling moment at any speed flap asymmetry causes a large difference in clmax whereas slat asymmetry causes a large rolling moment at any speed flap asymmetry causes a large rolling moment whereas slat asymmetry causes a large yawing moment

exemple 440 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 flap asymmetry causes a large rolling moment at any speed whereas slat asymmetry causes a large difference in clmax.

The airload on the horizontal tailplane tailload of an aeroplane in straight ?

Question 208-35 : Is in general directed downwards and will become less negative when the c g moves aft is in general directed upwards and will increase when c g is moved forward will in principle be zero on transport aeroplanes without an electronic flight control system fly by wire due to the trim system is in general directed downwards and will always become less negative in a linear fashion with increasing airspeed

exemple 444 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 is in general directed downwards and will become less negative when the c.g. moves aft.

The boundary layer of a wing is ?

Question 208-36 : A layer on the wing in which the stream velocity is lower than the free stream velocity created by the normal shock wave at transonic speeds a turbulent flow around the wing caused by suction on the upper wing surface

exemple 448 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 a layer on the wing in which the stream velocity is lower than the free stream velocity.

If the aspect ratio of a wing increases whilst all other relevant factors ?

Question 208-37 : Decrease increase remain constant remain constant only for a wing consisting of symmetrical aerofoils

exemple 452 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 lif 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 decrease.

On a large transport aeroplane the auto slat system ?

Question 208-38 : Extends the slats automatically when a certain value of angle of attack is exceeded provides for automatic slat retractionafter take off ensures that the slats are always extended when the ground/flight system is in the 'ground' position assist the ailerons

exemple 456 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 extends the slats automatically when a certain value of angle of attack is exceeded.

How does the total drag change in straight and level flight at constant mass as ?

Question 208-39 : Initially decreases then increases decreases increases initially increases then decreases

exemple 460 initially decreases, then increases. — . /com en/com032 209 jpg. initially decreases, then increases.

How is stall warning presented to the pilots of a large transport aeroplane ?

Question 208-40 : Stick shaker and/or aerodynamic buffet stick pusher stall warning light only aural warning only

exemple 464 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 stick shaker and/or aerodynamic buffet.

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