Question 273-1 : Given aeroplane mass 50 000kgliftdrag ratio 12thrust per engine 28 000nassumed g 10ms²for a straight steady wings level climb of a three engine aeroplane the one engine inoperative climb gradient is ? [ Analysis topography ]

Question 273-2 : Given aeroplane mass 50 000kgliftdrag ratio 10thrust per engine 30 000nassumed g 10ms²for a straight steady wings level climb of a three engine aeroplane the all engines climb gradient is ?

80%.

Climb gradient = thrust drag weight x 100liftdrag ratio 10 > when lift is 1 drag is 01total trust = 3 x 30000 n = 90000 nweight = 50000 kg x 10ms² = 500 000 nlift = 500000 x 1 = 500000 ndrag = 500000 x 01 = 50000 nclimb gradient = 90000 50000 500000 x 100climb gradient = 8%

Question 273-3 : What is the heading change after 10 seconds of an aeroplane performing a rate one turn ?

30 degrees.

A standard rate turn is defined as a 3° per second turn which completes a 360° turn in 2 minutes this is known as a 2 minute turn or rate one = 180°minute 10 secondes x 3°sec = 30 degrees

Question 273-4 : An aeroplane has a stall speed of 78 kt at its mass of 6850 kg what is the stall speed when the mass is 5000 kg ?

67 kt.

Change in mass ratio = new mass old mass = 50006850 = 073stall speed of an aircraft changes in proportion to the square root of the change in mass square root of 073 = 0855original stall speed = 78 ktstall speed for a weight of 5000 kg ==> 78 x 0855 = 67 kt

Question 273-5 : In order to fly a rate one turn at a higher airspeed the bank angle must be ?

Increased and the turn radius will increase.

A standard rate turn is defined as a 3° per second turn which completes a 360° turn in 2 minutes this is known as a 2 minute turn or rate one = 180°minute turn radius = tas² ms gtan bank angle rate of turn = tas kt 20 x 314 x turn radius in order to maintain a 3° per second turn at a higher speed you must increase the bank angle your turn radius will increase

Question 273-6 : Which of these statements about vmcg determination are correct or incorrect i during vmcg determination nose wheel steering may be usedii during vmcg determination the cg should be on the forward limit ?

I is incorrect ii is incorrect.

Vmcg the minimum control speed on the ground is the calibrated airspeed during the take off run at which when the critical engine is suddenly made inoperative it is possible to maintain control of the aeroplane using the rudder control alone without the use of nosewheel steering as limited by 667 n of force 150 lbf and the lateral control to the extent of keeping the wings level to enable the take off to be safely continued using normal piloting skillthe nosewheel steering is disconnected because the value of vmcg must also be applicable on wet andor slippery runwaysin the determination of vmcg assuming that the path of the aeroplane accelerating with all engines operating is along the centreline of the runway its path from the point at which the critical engine is made inoperative to the point at which recovery to a direction parallel to the centreline is completed may not deviate more than 91 m 30 ft laterally from the centreline at any pointvmc must be established with the most unfavourable centre of gravity at take off the cg should be on the aft limit

Question 273-7 : An aeroplane maintains straight and level flight at a speed of 2 * vs if a vertical gust causes a load factor of 2 the load factor n caused by the same gust at a speed of 13 vs would be ?

N = 165.

1 x 132 = 065 g065g + 1g = 165g in straight and level flight load factor is 1g

Question 273-8 : When is a turn co ordinated ?

When the longitudinal axis of the aeroplane at the cg is tangential to the flight path.

Question 273-9 : An aeroplane flying at 100 kt in straight and level flight is subjected to a disturbance that suddenly increases the speed by 20 kt assuming the angle of attack remains constant the load factor will initially ?

Increase to 144.

Load factor is proportional to lift and lift is proportional to v²new load factor old load factor = new speed old speed ²new load factor = old load factor x 120 100 ² = 1 x 12² = 144

Question 273-10 : Regarding the lift formula if airspeed doubles lift will ?

Be 4 times greater.

Question 273-11 : Whilst maintaining straight and level flight with a lift coefficient cl = 1 what will be the new approximate value of cl after the speed is increased by 30% ?

060.

Aircraft is maintaining level flight only the speed will change by 30% lift will not change lift = cl 12rho v² s rho = density v was 1 now v is 130lift = cl 12rho 130² slift = cl 12rho 169 sin order to maintain lift to its original value when v was 1 we can only divide cl by 169 surface and 12rho can't be changed cl was 1 now cl = 1169 = 05917 approximate value 060

Question 273-12 : The centre of pressure is the point ?

On the chord line of an aerofoil section through which the resultant of the lift forces acts.

The centre of pressure moves with the angle of attack 669

Question 273-13 : The angle of attack of an aerofoil is the angle between the ?

Chord line and the relative airflow.

Question 273-14 : The forward speed of helicopters is limited by ?

Retreating blade stall and advancing blade tip speed.

Question 273-15 : Reverse airflow over part of the rotor is associated with ?

Question 273-16 : In forward flight if the rotor rpm increase above that specified ?

The large centrifugal forces impose severe and possibly excessive loads on the hub.

Question 273-17 : In the case of a symmetrical aerofoil ?

Pitching moment variations due to centre of pressure movement are small.

Question 273-18 : In still air hover ground cushion is normally of practical value up to a rotor height above ground ?

Question 273-19 : A 'vortex ring state' ?

Question 273-20 : During autorotative descent main rotor rpm are maintained by ?

The lift force created by the upflow of air.

Question 273-21 : In hovering for a single rotor helicopter whose main rotor turns clockwise from above the thrust of the main rotor will be mainly vertical but with a slight orientation towards the ?

Right.

Question 273-22 : The center of the pressure of a symmetrical aerofoil section is behind the leading edge approximately at the following % of the section chord at ?

Question 273-23 : The forces acting on a symmetrical aerofoil element when the upstream airflow is parallel to the chordline is ?

Only drag.

Question 273-24 : Thicknesschord ratio of an aerofoil section is expressed in percentage of ?

Chord.

Question 273-25 : The center of pressure of an aerofoil element ?

Question 273-26 : The blades of a rotor are in track an upward bent outboard trim tab of one of one of the blades influences the rotor blade in rotation as follows ?

The blade rotates above the plane of rotation with neutral trim tab position.

Bending the tab up on the trailing edge of the blade would tend to increase pitch angle the track of the blade would be higher 1628

Question 273-27 : The formula take off massrotor disc area is used to calculate ?

Rotor disc loading.

Question 273-28 : The angle of attack is the angle determined by ?

The chord line and the relative airflow.

Question 273-29 : The coning angle of a fully articulated rotor is defined by ?

Lift centrifugal force and weight of the blade.

Question 273-30 : The resulting rolling moment on the main rotor hub due to the asymmetrical airflow on the blades in forward flight is reduced by ?

Blade flapping.

Question 273-31 : For an autogyro the power from engines provided to the rotor is ?

Nil.

Question 273-32 : In an autogyro the lift force comes from ?

The forward movement.

Question 273-33 : On an autogyro the engine power output is used ?

To ensure forward motion.

Question 273-34 : An anti torque rotor is necessary on ?

A single rotor helicopter.

Question 273-35 : The rotor thrust is always ?

Perpendicular to the tip path plane.

Question 273-36 : On an articulated rotor variations in attitude of the tip path plane are due to ?

Blades flapping angles.

Question 273-37 : The rotation axis of the main rotor is always ?

Perpendicular to the hub plane.

The hub plane also called the reference plane is always 90° to the shaft axis it does not move and is not affected by different types rotor head 1610

Question 273-38 : Helicopter rotor blades are designed with twist or taper to incorporate washout a design that ?

Ensures adequate lift distribution along the span of the blade.

Question 273-39 : In autorotation the blades are free to rotate because ?

A freewheel unit disengages the rotor from the engine.

Question 273-40 : The effect of ground cushion on a hovering helicopter is greatest on ?

Level ground with no wind.