Question 256-1 : What wing shape or wing characteristic is the least sensitive to turbulence ? [ Explanation maintenance ]

Question 256-2 : What is the si unit of measurement for power ?

Nms.

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 256-3 : The use of a slot in the leading edge of the wing enables the aeroplane to fly at a slower speed because ?

It delays the stall to a higher angle of attack.

Question 256-4 : For a subsonic flow the continuity equation states that if the cross sectional area of a tube increases the speed of the flow ?

Decreases.

Question 256-5 : If the continuity equation is applicable what will happen to the air density rho if the cross sectional area of a tube changes low speed subsonic and incompressible flow ?

Rho1 = rho2.

Question 256-6 : Bernoulli's equation can be written as pt = total pressure ps = static pressure q = dynamic pressure ?

Pt q = ps.

Pt total pressureps static pressurepd dynamic pressure 12 x density x tas² bernoulli's theorem is pt = ps + pd

Question 256-7 : Which one of the bodies in motion all bodies have the same cross section area will have lowest drag err a 081 289 ?

Body c.

Drag is the force that resists movement of an aircraft through the air there are two basic types parasite drag and induced drag the first is called parasite because it in no way functions to aid flight while the second induced drag is a result of an airfoil developing liftwhen the air has to separate to move around a moving aircraft and its components it eventually rejoins after passing the body how quickly and smoothly it rejoins is representative of the resistance that it creates which requires additional force to overcome com encom080 289jpgform drag is the portion of parasite drag generated by the aircraft due to its shape and airflow around it

Question 256-8 : Increasing dynamic pressure will have the following effect on the total drag of an aeroplane ?

At speeds above the minimum drag speed total drag increases.

If you are below the minimum drag speed ie speed unstable region and increase the dynamic pressure forward speed then the total drag reduces until you reach the point of minimum dragif you are above the minimum drag speed total drag will then increase as speed is increased further com encom032 209jpg

Question 256-9 : Increasing air density will have the following effect on the drag of a body in an airstream angle of attack and tas are constant ?

The drag increases.

Drag = 12 cd s rho v²in the equation rho is density and v is tas in ms

Question 256-10 : Which part of the aeroplane has the largest effect on induced drag ?

Wing tip.

Since there is a considerable pressure difference between lower and upper surfaces of a wing tip vortices are produced at the wingtips these tip vortices will then roll up and get around the local edges of a wing this phenomenon will have the largest effect on induced drag

Question 256-11 : Winglets ?

Decrease the induced drag.

Since there is a considerable pressure difference between lower and upper surfaces of a wing tip vortices are produced at the wingtips these tip vortices will then roll up and get around the local edges of a wing this phenomenon will reduce the lift at the wingtip station so they can be represented as a reduction in effective wing spanexperiments have shown that wings with square or sharp edges have the widest effective spanto compensate this loss three solutions are tip tank extra wing span and winglet winglets are small nearly vertical lifting surfaces mounted rearward andor downward relative to the wing tips com encom080 293ajpg com encom080 293bjpg winglets decrease the induced drag

Question 256-12 : Interference drag is the result of ?

Aerodynamic interaction between aeroplane parts eg wingfuselage .

com encom080 294jpga wing root can cause interference drag

Question 256-13 : Which line represents the total drag line of an aeroplane err a 081 295 ?

Line c.

This is the drag to tas curve com encom032 209jpg

Question 256-14 : From an initial condition of level flight the flaps are retracted at a constant pitch attitude the aeroplane will subsequently ?

Start to sink.

Lift = cl x 12 rho v² x scl = lift coefficientrho = densityv = tas in ms s = surfacethe question states at a constant pitch attitude it means 'at a constant angle of attack' so cl does not changes surface will be decreased when flaps are retracted lift will reduce the aeroplane will subsequently start to sinkthe question does not state 'fowler flaps' which modify surface and camber in this case flaps generally speaking increase the camber which increases clmax

Question 256-15 : From an initial condition of level flight the flaps are extended at a constant pitch attitude the aeroplane will subsequently ?

Start to climb.

If the flaps are extended with no change made to angle of attack the coefficient of lift will increase and the aircraft will gain altitudeflaps generally speaking increase the camber which increases clmax

Question 256-16 : Compared with the clean configuration the angle of attack at clmax with trailing edge flaps extended is ?

Smaller.

Changing the configuration will change the properties of the airfoil and alter the lift and drag coefficientswith trailing edge flaps extended the lift coefficient will increasethen the angle of attack will be decreased at clmax com encom080 298jpgclmax is reached at a lower angle of attack with trailing edge flaps extended

Question 256-17 : The sensor of a stall warning system can be activated by a change in the location of the ?

Stagnation point.

The stagnation point is the point at which the stream of air moving toward the wing divides into two streams one flowing above and the other flowing below the wing com encom080 302ajpg com encom080 302bjpgin fluid dynamics a stagnation point is a point in a flow field where the local velocity of the fluid is zero

Question 256-18 : The diagram shows the parameter x versus tas if a horizontal flight is considered the axis x shows err a 081 315 ?

The induced drag.

This diagram is already used for question n°1319 'the diagram shows the parameter x versus tas if a horizontal flight is considered the axis x shows the coefficient of lift'here we can only choose 'the induced drag' com encom032 209jpg

Question 256-19 : How are the speeds shown in the figure at point 1 and point 2 related to the relative windairflow v err a 081 316 ?

V1 = 0 and v2 > v.

Question 256-20 : An aerofoil with positive camber at a positive angle of attack will have the highest flow velocity ?

On the upper side.

On the upper wing surface the airflow will have to travel a longer distance due to the camber than the airflow on the lower side in a same time period com encom080 317jpg

Question 256-21 : The forces of lift and drag on an aerofoil are respectively normal and parallel to the ?

Relative windairflow.

Question 256-22 : Ground effect has the following influence on the landing distance ?

Increases.

As the airplane flies down from free air into ground effect the reduction of induced drag as it nears the runway comes into effect to make the airplane float past the point of intended touchdownin the common case of an airplane coming in with excessive speed the usable portion of the runway may slip by with the airplane refusing to settle down to land a go around will probably be necessary on short fields approach as slowly as is consistent with safety

Question 256-23 : 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 ?

Tas is higher at the higher altitude.

Level flight at the same angle of attack means the same iaslift formula = cl x 12 rho v² x scl = lift coefficientrho = densityv = tas in ms s = surfacelift at altitude 1 = lift at altitude 2they say same angle of attack thus cl is the same surface does not change and there is no compressibility effectssince rho decreases with altitude tas must increase in order to keep rho x v² unchanged

Question 256-24 : The lift to drag ratio determines the ?

Horizontal glide distance from a given altitude at zero wind and zero thrust.

Question 256-25 : Which type of flap is shown in the picture err a 081 330 ?

Fowler flap.

com encom080 182jpg fowler flap slides backwards before hinging downwards thereby increasing both camber and chord creating a larger wing surface better tuned for lower speeds it also provides some slot effect

Question 256-26 : Which type of flap is shown in the picture err a 081 331 ?

Split flap.

com encom080 182jpg

Question 256-27 : The application of the area rule on aeroplane design will decrease the ?

Wave drag.

The area rule is an important concept related to the drag on an aircraft or other body in transonic and supersonic flight the area rule came into being in the early 1950s when production fighter designs began pushing ever closer to the sound barrier designers had found that the drag on these aircraft increased substantially when the planes travelled near mach 1 a phenomenon known as the transonic drag rise illustrated below increase in wave drag at transonic mach numbers com encom080 334bjpgthis increase in drag is due to the formation of shock waves over portions of the vehicle which typically begins around mach 08 and this drag increase reaches a maximum near mach 1 because of its source this type of drag is referred to as wave drag

Question 256-28 : At a constant angle of attack which of the following factors will lead to an increase of ground distance during a glide and with zero thrust ?

Tailwind.

Question 256-29 : The wing of an aeroplane will never stall at low subsonic speeds as long as ?

Question 256-30 : The induced drag coefficient cdi is proportional with ?

Cl².

The coefficient of induced drag cdi = cl² pi x ar cl is lift coefficientpi is 314159ar is aspect ratiocdi is proportional with cl²

Question 256-31 : The stall speed increases when all other factors of importance being constant ?

Pulling out of a dive.

Pulling out of a dive com encom080 359jpgan aircraft is in a dive with an airspeed of 100 knots when the pilot pulls back sharply on the elevator control gravity and centrifugal force prevent an immediate alteration of the flightpath but the aircraft's aoa changes abruptly from quite low to very high since the flightpath of the aircraft in relation to the oncoming air determines the direction of the relative wind the aoa is suddenly increased and the aircraft would reach the stalling angle at a speed much greater than the normal stall speed

Question 256-32 : The angle of attack of a wing profile is defined as the angle between ?

The undisturbed airflow and the chordline.

Question 256-33 : In which phase of the take off is the aerodynamic effect of ice located on the wing leading edge most critical ?

The last part of the rotation.

Lift starts during rotation ice located on the wing leading edge will affect the airflow and thus will dramatically degrade the lift com encom080 382jpgyou are at high speed and after v1 it is too late to stop the aircraft since the remaining runway distance is too short

Question 256-34 : Which statement is correct at the speed for minimum drag subsonic ?

The gliding angle is minimum assume zero thrust .

Minimum glide angle occurs at the speed for minimum drag if you want to travel the maximum distance possible with zero thrust you need to fly at the speed that wich gives maximum lift to drag ratio vmd velocity for minimum drag

Question 256-35 : The induced angle of attack is the result of ?

Downwash due to tip vortices.

Induced angle of attack is a slight decrease in the effective angle of attack of a wing due to the diversion of the air stream by the wings as the wings produce the downwash that ultimately engenders lift to support the aircraft the downwards twist of the air stream shallows the effective angle of attack slightly

Question 256-36 : The following factors increase stall speed ?

An increase in load factor a forward cg shift decrease in thrust.

Stall speed increases with the square root of the load factorwith a forward cg shift you have to increase downward force on the tail to maintain equilibrium thus stall speed increasesthe thrust line is pointing upwards and making a small contribution to lift a decrease in thrust will increase stall speed

Question 256-37 : The stall speed ias will change according to the following factors ?

May increase with altitude especially high altitude will increase during icing conditions and will increase when the cg moves forward.

A stall occurs when the smooth airflow over the airplane's wing is disrupted and the lift degenerates rapidly this is caused when the wing exceeds its critical angle of attack this can occur at any airspeed in any attitude with any power setting altitude 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 amounthowever at higher altitudes we consider another factor the compresibility that affects the anemometer and hence increases the reading of iasresuming the ias stall speed is considered constant at lower altitudes below 10000 ft and increases with altitude at higuer altitudes due to compresibility effects wing contamination wings covered with rime ice hoar frost and remains of bugs and dirt will cause an early separation of the boundary layer and the stall speed will increase sometimes even by 4% remember that the same applies to the propeller but then a decrease in thrust will be the result forward cg the airplane will stall at a higher speed with a forward cg location this is because the stalling angle of attack is reached at a higher speed due to increased wing loading

Question 256-38 : The stalling speed in ias will change according to the following factors ?

Increase during turn increased mass and forward cg location.

One quick note an airplane always stalls at the same critical angle of attack an airplane can stall at any airspeedthus the stall can always reach the critical angle of attack at any airspeed a forward cg = higher stall speedan aft cg = lower stall speedturning there is a bit of loss in the vertical component of lift because some of the lift was diverted to cause the plane to bank for example an aircraft in a 30° bank increases it's stall speed by 7%an increase in mass = higher stall speedincreased mass has the same outcome as increased g so far as the wing looks at weightwe need more lift due to increased mass we have to either increase the speed v or the angle of attack cl in the lift formula lift = 12 rho x v² x wing area x cl

Question 256-39 : The stalling speed in ias will change according to the following factors ?

May increase during turbulence and will always increase when banking in a turn.

The stalling speed may increase during turbulence altitude bank and pitch will change during turbulence therefore stall speed may increase with increased load factorthe stalling speed will always increase when banking in a turn stall speed increases with the square root of the load factor and the load factor in a turn is 1cos bank angle

Question 256-40 : On a symmetrical aerofoil the pitching moment for which cl=0 is ?

Zero.