During autorotative flight ? [ Question security ]

Question 248-1 : The fuselage will tend to rotate in the same direction as the rotor yaw is controlled by the cyclic control since the low tail rotor rpm would exert insufficient force no attempt must be made to control yaw through the pedals as the power required to drive the tail rotor would derive from the main rotor reducing the rpm disastrously collective and cyclic inputs work in the reverse sense to powered flight

Blade sailing with the attendant possibility of a blade strike on the tail boom ?

Question 248-2 : During very low rotor rpm conditions particularly whilst starting or stopping the engine in gusty conditions during an autorotative descent whilst hovering in strong winds when carrying out extreme manoeuvres involving or approaching zero 'g'

The primary factor which prevents the main rotor blade coning upwards on an ?

Question 248-3 : The centrifugal force acting on the blades gravity acting on the blades the lift developed by the blades coriolis effect

Blades with a positive coning angle flapping upwards tend to ?

Question 248-4 : Increase rotational speed decrease rotational speed stall increase the angle of attack

An increase in angle of attack of a rotor blade element below the stall angle ?

Question 248-5 : Drag and lift forces induced drag and a decrease in parasite drag but no change in lift unless rotor speed is increased induced drag and parasite drag but a reduction in lift lift only

A shrouded tail rotor fenestron ?

Question 248-6 : Largely removes lift dissymmetry and the attendant need for cyclic feathering of the tail rotor removes the need for tail rotor pitch control allowing yaw control to be achieved by a fin and rudder allows the tail rotor to be used for pitch as well as yaw control permits greater cg movement fore and aft

During an autorotative descent the maximum gliding distance will be obtained at ?

Question 248-7 : A speed greater than that associated with the minimum rate of descent the speed associated with the minimum rate of descent a speed slightly less than that associated with the minimum rate of descent the minimum speed that will sustain rotor rpm

In forward flight the lift produced by a given blade element is dependent upon ?

Question 248-8 : Angle of attack and the square of its air speed angle of attack and the square of its rotational speed pitch angle and the square of its rotational speed pitch angle and the square of the forward speed of the helicopter

When the cyclic pitch control is forward a main rotor blade will reach its ?

Question 248-9 : On the retreating side in the rear most position on the advancing side in the fore most position

Blade hinges arranged with a 'delta three' hinge effect ?

Question 248-10 : Decrease their pitch angle with flap up have no need to change their pitch cyclically without a pilot input decrease their pitch angle with blade dragging increase their pitch angle with flap up

Some tail rotor hinges are not perpendicular to the feathering axis in order to ?

Question 248-11 : Reduce the effects of dissymmetry of lift with forward speed provide a pitch change hinge free from phase lag cater for centrifugal twisting moment produce a stabilising lift component when lift is increased at the main rotor by an increase in rpm

The normal or yaw axis of a helicopter is a straight line ?

Question 248-12 : Passing through the centre of gravity perpendicular to the longitudinal and lateral axes passing through the centre of lift perpendicular to the relative airflow coincident with the main rotor axis passing through the centre of gravity and perpendicular to the helicopter velocity

The angle of attack of an aerofoil section is the angle between the ?

Question 248-13 : Chord line and the relative airflow plane of rotation and the direction of flight of the helicopter lower surface of the aerofoil and the relative airflow chord line and the horizontal

A helicopter is statically stable when it exhibits the ?

Question 248-14 : Tendency to return to its original attitude after a disturbance tendency to pitch at low airspeed ability to rotate about an axis ability to accelerate in forward flight without excess fuselage pitch down

The amount of lift produced by a given helicopter rotor blade element is ?

Question 248-15 : The angle of attack of the blade the square of the air velocity relative to the blade element and the air density the angle of attack of the blade the square of the forward speed of the helicopter and the air density the pitch angle the square of the forward speed of the helicopter and the square root of the air density the angle of attack of the blade the square root of the relative air velocity to the blade element and the air density

Phase lag is the ?

Question 248-16 : Azimuthal angle through which a blade moves between a pitch value input and the corresponding flapped position time between collective pitch increase and the restoration of the original rpm time between cyclic pitch control inputs and rotor disc attitude change the angle in the plane of rotation by which a dragging rotor blade lags its neutral position

As speed increases the parasite drag of a helicopter fuselage will ?

Question 248-17 : Tend to cause the nose to pitch down have no effect on pitching moments tend to cause the nose to pitch up only tend to cause the helicopter to yaw in the direction of rotation of the main rotor in addition to pitch up

'coning angle' is defined as the angle between the rotor blade's longitudinal ?

Question 248-18 : Tip path plane rotor mast plane containing the lateral and longitudinal axes of the helicopter horizontal

Disc loading is defined as the ?

Question 248-19 : Ratio of the total weight of the helicopter per unit of the disc area weight of the main rotor blades maximum centrifugal loading of the main rotor hub assembly increase in rotor thrust required to compensate for accelerations during manoeuvre

In order to reduce the effects of retreating blade stall on a helicopter in ?

Question 248-20 : Collective pitch should be lowered to decrease pitch power should be reduced and collective pitch increased at once to reduce speed cyclic control should be pushed forward to increase speed cyclic control should be pulled back to decrease speed in a flare manoeuvre

If a helicopter is loaded for flight and the centre of gravity is within limits ?

Question 248-21 : The centre of gravity position needs to be calculated for landing as fuel tanks are always located on the centre of gravity the centre of gravity will not change during flight the centre of gravity may well move as fuel and oil are consumed but since the aircraft will be lighter than at take off the movement will not be critical for landing it is an airworthiness requirement that provided the centre of gravity is within limits on take off it will remain within limits for landing as fuel and oil are consumed during flight

In order to produce a stable teetering rotor it may be necessary to ?

Question 248-22 : Stabilise it by use of rotating masses give it a preset coning angle embody delta three hinges use an odd number of blades

A tilt of the rotor disc plane will cause the helicopter to accelerate ?

Question 248-23 : In the direction of tilt 90 degrees to the direction of tilt in the direction of rotation against the direction of tilt in the direction in which the fuselage is pointing but the pilot should rotate the fuselage against the direction of tilt in order to maintain balanced flight

The avoid areas in a 'height velocity diagram' define the height/velocity ?

Question 248-24 : From which safe autorotative descent and landing after engine failure may not easily be accomplished from which it is not possible to operate the helicopter due to the engine being power limited from which a safe climb out may not be made having regard to obstacle clearance in which it is possible only to make forward as opposed to sideways or rearwards translational flight

In a hingeless rotor head flapping movements ?

Question 248-25 : Are accommodated for by the rotor blades flexible attachements to the hub do not arise since the fuselage always follows the rotor head are accommodated for by the whole rotor hub tilting are accommodated by flapping hinges

When a cyclic control input has been made the rotor blade pitch will be ?

Question 248-26 : Increasing for one half revolution and decreasing for the next half increasing for one whole revolution and decreasing the next increasing or decreasing immediately and remaining at the new position until a new control input is made increasing for one quarter revolution remaining constant for a quarter decreasing for a quarter and then remaining constant for the last quarter

What effect does an increase in density altitude have on the amount of anti ?

Question 248-27 : Increased because power required increases and the tail rotor is less effective decreased because the tail rotor is more effective maintained in the same position because density will affect the main and tail rotors equally decreased due to less power being required to drive the main rotor

If the centre of gravity is at the rear limit ?

Question 248-28 : Then forward cyclic travel is reduced then rearward cyclic travel is reduced then forward cyclic travel is increased then rearward cyclic travel is not affected

With a centre of gravity position near the front limit what will be the effect ?

Question 248-29 : Nose down cyclic stick back nose up cyclic stick back with the cg within limits there would be no change nose down cyclic stick forward

The principal forces acting on a helicopter in forward flight are ?

Question 248-30 : Main rotor thrust weight parasite drag and main rotor profile drag main rotor thrust lift and parasite drag main rotor thrust weight and main rotor profile drag lift and weight

A nose down pitch attitude in forward flight is caused by ?

Question 248-31 : The horizontal component of total rotor thrust acting above parasite drag drag acting above the thrust lift acting forward of weight the vertical component of total rotor thrust acting forward of the weight

To increase forward speed in straight and level flight ?

Question 248-32 : Total rotor thrust must be increased total rotor thrust must be reduced as translational lift is achieved total rotor thrust must be reduced initially then increased total rotor thrust remains constant

The induced flow component of airflow through the rotor disc ?

Question 248-33 : Decreases with forward flight increases with forward speed to increase the mass flow in forward flight is evenly distributed about the disc remains constant throughout the helicopters speed range

During a transition into forward flight from the hover and maintaining level ?

Question 248-34 : Total rotor thrust increases total rotor thrust decreases total rotor thrust and power increase power increases but total rotor thrust decreases

When the induced flow and the perpendicular component of horizontal flow are of ?

Question 248-35 : The flow throught the disc will be at a minimum the flow through the disc will be at a maximum for a particular blade pitch angle the angle of attack will be at a minimum maximum power will be required to maintain the correct rotor r p m

With weight on the wheels/skids and take off rotor rpm set ?

Question 248-36 : The only power required to drive the main rotor is the profile power the induced power is high parasite power plus induced power equals rotor profile power rotor profile power is at a maximum

The parasite power required by a helicopter ?

Question 248-37 : Is a minimum at the hover is a minimum when total power required is a minimum increases in direct proportion to forward speed is a minimum at mean sea level

The total power required curve is the resultant of ?

Question 248-38 : Induced power + rotor profile power + parasite power induced power parasite power rotor profile power induced power + rotor profile power parasite power power required + power in hand

The maximum range speed for piston engine helicopters in zero wind conditions ?

Question 248-39 : Drawing a line tangential to the power required curve from the point of origin of the graph noting the speed on the graph at which the power required is a minimum drawing a line tangential to the power required curve from the power available origin noting the speed on the graph where the ratio of power in hand to forward speed is greatest

An overpitched situation is most likely to occur ?

Question 248-40 : When manoeuvring at the hover when induced power is increasing when power required is low when carrying out a flare manoeuvre