Question 257-1 : 'a line connecting the leading and trailing edge midway between the upper and lower surface of a aerofoil' this definition is applicable for ? [ Explanation maintenance ]

Question 257-2 : What is the stagnation point ?

The point where the velocity of the relative airflow is reduced to zero.

Question 257-3 : What is the effect on induced drag of mass and speed changes all other factors of importance remaining constant ?

Decreases with increasing speed and decreasing mass.

We know that induced drag is proportional to the angle of attack so if you reduce speed you must increase your angle of attack to maintain the same lift assuming we want to stay in level flight if we increase speed you must decrease your angle of attack thus induced drag will decreaseit's basicaly the same for the mass at a given speed and altitude to maintain level flight with a lighter aircraft less angle of attack is required thus induced drag will decrease

Question 257-4 : What increases the critical angle of attack use of ?

Slats.

Question 257-5 : When considering a swept back wing with no corrective design features at the stall ?

Tip stall will occur first which produces a nose up pitching moment.

Question 257-6 : Which boundary layer when considering its velocity profile perpendicular to the flow has the greatest change in velocity close to the surface ?

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

Question 257-7 : The si unit of measurement for pressure is ?

Nm².

Icao annex 5 units of measurement attachment b 2 mass force and weight 21 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 nm² = pa energy nm = j and power nms = w

Question 257-8 : The polar curve of an aerofoil section is a graphic relationship between ?

Lift coefficient cl and drag coefficient cd.

Question 257-9 : The speed for minimum glide angle occurs at an angle of attack that corresponds to assume zero thrust ?

Clcd max.

Question 257-10 : The value of the induced drag of an aeroplane in straight and level flight at constant mass varies linearly with ?

1v².

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

Question 257-11 : Upon extension of fowler flaps whilst maintaining the same angle of attack ?

Cl and cd increase.

Question 257-12 : True airspeed tas is ?

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 densityso tas is greater than ias with increasing altitude as density reducesfor 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 12 rho tas² rho = density

Question 257-13 : The span wise flow on an unswept wing is from the ?

Lower to the upper surface via the wing tip.

Img com encom080 459jpgthe 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

Question 257-14 : Total pressure is rho = density ?

Static pressure plus dynamic pressure.

Question 257-15 : The terms q and s in the lift formula are ?

Dynamic pressure and the area of the wing.

Lift formula = 12 rho cl x v² x swhere q or 12 rho v² is dynamic pressure rho = density v = speed in ms cl is coefficient of lift s is wing area

Question 257-16 : The stall speed ?

Increases with an increased weight.

Question 257-17 : Trailing edge flaps once extended ?

Degrade the best angle of glide.

Question 257-18 : Which statement concerning the local flow pattern around a wing is correct ?

By fitting winglets to the wing tip the strength of the wing tip vortices is reduced which in turn reduces induced drag.

Question 257-19 : Which statement is correct ?

Question 257-20 : While flying under icing conditions the largest ice build up will occur principally on ?

The frontal areas of the aircraft.

Question 257-21 : Which statement is correct ?

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

Question 257-22 : Which statement is correct ?

Question 257-23 : During a climbing turn to the right the ?

Question 257-24 : Dividing lift by weight gives ?

Load factor.

Question 257-25 : Dangerous stall characteristics in large transport aeroplanes that require stick pushers to be installed include ?

Excessive wing drop and deep stall.

The stick pusher inhibits excessive wing drop and deep stallat approximately one knot above stall speed pre programmed stick forces automatically move the stick forward preventing the stall from developing

Question 257-26 : Bernoulli's law states note rho is the mean sea level density under isa conditions pstat is static pressure pdyn is dynamic pressure ptot is total pressure ?

Question 257-27 : Assuming zero wing twist the wing planform that gives the highest local lift coefficient at the wing root is ?

Rectangular.

Img com encom080 496jpg com encom080 496ajpg

Question 257-28 : Given the following aeroplane configurations 1 clean wing2 slats only extended3 flaps only extendedplace these configurations in order of increasing critical angle of attack ?

3 1 2.

The angle at which the stall occurs is called the critical angle of attack3 trailing edge flap decrease the critical angle of attack and increase the value of clmax1 critical angle of attack of a clean wing is higher than a wing with flaps only extended but generate less lift2 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

Question 257-29 : Floating due to ground effect during an approach to land will occur ?

Question 257-30 : An aeroplane climbs to cruising level with a constant pitch attitude and maximum climb thrust assume no supercharger how do the following variables change during the climb gamma = flight path angle ?

Gamma decreases angle of attack increases ias decreases.

Your flight path angle gamma will decrease because as you climb the thrust will decrease 682if you maintain the same pitch angle angle of attack will increaseand 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

Question 257-31 : An aerofoil is cambered when ?

The line which connects the centres of all inscribed circles is curved.

com encom080 520pngthe 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

Question 257-32 : An aeroplane being manually flown in the speed unstable region experiences a disturbance that causes a speed reduction if the altitude is maintained and thrust remains constant the aeroplane speed will ?

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

Question 257-33 : A slat will ?

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 encom080 524jpga 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

Question 257-34 : A flat plate when positioned in the airflow at a small angle of attack will produce ?

Both lift and drag.

Question 257-35 : An aeroplane has the following flap positions 0° 15° 30° 45° slats can also be selected generally speaking which selection provides the highest positive contribution to the clmax ?

The slats from the retracted to the take off position.

Question 257-36 : An increase in wing loading will ?

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

Question 257-37 : 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 ?

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 rudderhowever 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

Question 257-38 : 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 cg 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 encom080 560jpgwith 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

Question 257-39 : 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 velocityfree 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

Question 257-40 : 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 forthe 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 encom080 570jpgfor 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