Question 282-1 : In a stationary hover relative to the ground the position of the advancing blade relative to the pilot ? [ Attainment AIM ]

Question 282-2 : The effect of a delta three hinge on a tail rotor is that the blade pitch ?

Decreases when the blade flaps in the direction of the thrust vector.

Question 282-3 : Flapping of the tail rotor in forward flight is reduced by the use of ?

Delta three flapping hinges.

Question 282-4 : Which of the following ground surfaces gives the best ground cushion ?

Ice covered level concrete.

Question 282-5 : The onset of vortex ring state settling with power can be identified by ?

Vibration cyclic stick shake random yawing increased rate of descent.

Question 282-6 : The recommended recovery action from overpitching is ?

Lower the collective lever to increase rotor rpm.

Question 282-7 : Tail rotor blade counterweights are sometimes used in order to ?

Prevent the blades from going to minimum pitch in case of control failure.

Question 282-8 : Maximum rotor rpm in powered flight is limited by ?

Blade and hub strength.

Question 282-9 : The correct tyre pressure of the undercarriage is important to prevent ground resonance when ?

Engaging a fully articulated rotor.

Question 282-10 : One feature that compensates for phase lag is ?

The advance angle.

Question 282-11 : Which moments or motions interact in a dutch roll ?

Rolling and yawing.

Question 282-12 : The tendency to dutch roll increases when ?

The static lateral stability increases.

Cqb15 december 2011

Question 282-13 : An example of a combined lateral and directional periodic motion is a ?

Dutch roll.

Cqb15 december 2011

Question 282-14 : The formula for the mach number is a= speed of sound ?

M= tas a.

Question 282-15 : The speed of sound is determined only by ?

Temperature.

Cqb15 december 2011 varegar tricky but you should focus in the formula lss local speed of sound = 3895 which is a constant x square root of temperature in kelvin it is obvious that temperature affects density and therefore density affects sound speed but keep focus in the previous formula

Question 282-16 : In a stationary subsonic streamline flow pattern if the streamlines converge in this part of the pattern the static pressure i will and the velocity ii will ?

I decrease ii increase.

1466static pressure decreases in a venturi and airflow speed increases

Question 282-17 : The si units of air density i and force ii are ?

I kg m³ ii n.

The use of units follow the international rules and style conventions pdf668

Question 282-18 : The unit of dynamic pressure 'q' is ?

N m².

The use of units follow the international rules and style conventions pdf668

Question 282-19 : Which formula or equation describes the relationship between force f acceleration a and mass m ?

F=ma.

Force energy brought to bear which tends to cause a motion or changemass a measure of the amount of material contained in a bodyacceleration rate of change of velocity velocity + time or distance + time²

Question 282-20 : Static pressure is acts ?

In all directions.

Static pressure is atmospheric pressure measured at a point where there is no external disturbance and the flow of air over the surface is perfectly smooth

Question 282-21 : Which one of the following statements about bernoulli's theorem is correct ?

The dynamic pressure increases as static pressure decreases.

Pt total pressureps static pressurepd dynamic pressure 12 x density x tas² bernoulli's theorem is pt = ps + pdthen if pd inscreases ps decreases as pt always remains constant

Question 282-22 : If in a two dimensional incompressible and subsonic flow the streamlines converge the static pressure in the flow will ?

Decrease.

1466static pressure decreases in a venturi and airflow speed increases

Question 282-23 : Bernoulli's equation can be written as pt= total pressure ps = static pressure and q=dynamic pressure ?

Question 282-24 : Which of the following statements about boundary layers is correct ?

The turbulent boundary layer has more kinetic energy than the laminar boundary layer.

Question 282-25 : On an asymmetrical single curve aerofoil main rotor blade element in subsonic airflow at low angle of attack when the angle of attack is increased the centre of pressure will ?

Move forward.

The pressure created by an aerofoil at any point may be represented by a vector at right angles to its surface whose length is proportional to the difference between absolute pressure at the point and the free stream static pressureall of them can be represented by a single vector acting at a particular point called the centre of pressure 669the centre of pressure is a theoretical point on the chord line through which the resultant of all forces the total reaction is said to actits position is usually around 25% of the way from the leading edge a quarter chord behind the leading edge simply because more lift is generated there but it moves steadily forward as the angle of attack is increased until just before the stalling angle when it moves rapidly backwards the centre of pressure's most forward point is just before the stalling angle

Question 282-26 : With increasing angle of attack the stagnation point will move i and the point of lowest pressure will move ii respectively i and ii are ?

I down ii forward.

1576in red the stagnation point will move downin blue the point of lowest pressure will move forward

Question 282-27 : The correct drag d formula is ?

D= cd 12 rho v² s.

Where cd = drag coefficientrho = densityv = tas in ms s = surfacedrag is the force that opposes the forward motion of a body through the air it's an aerodynamic force on a body acting parallel and opposite to the relative wind

Question 282-28 : The value of the parasite drag in straight and level flight at constant weight varies linearly with the ?

Square of the speed.

Parasite drag is present any time the helicopter is moving through the air this type of drag increases with airspeed non lifting components of the helicopter such as the cabin rotor mast tail and landing gear contribute to parasite drag the tail rotor drag is also included in the parasite drag any loss of momentum by the airstream due to such things as openings for engine cooling creates additional parasite dragbecause of its rapid increase with increasing airspeed parasite drag is the major cause of drag at higher airspeeds 2421parasite drag varies with the square of the velocity therefore doubling the airspeed increases the parasite drag four timesthe power to overcome this drag is the parasite powerin the level flight at constant speed the main rotor induced power the rotor profile power and the parasite power are summed to give the total power required to drive the main rotor notation 'ptot mr'

Question 282-29 : Rotation about the lateral axis is called ?

Pitching.

2422

Question 282-30 : Rolling is the rotation of the helicopter about the ?

Longitudinal axis.

2422

Question 282-31 : An helicopter has static directional stability in a side slip to the right initially the ?

Nose of the helicopter tends to move to the right.

Directional stability is accomplished by placing a vertical stabilizer or fin to the rear of the centre of gravity on the upper portion of the tail section 2423 fuselage and fin for directional stability

Question 282-32 : Following a disturbance an helicopter oscillates about the lateral axis at a constant amplitudethe helicopter is ?

Statically stable dynamically neutral.

static stability static stability refers to the initial tendency or direction of movement back to equilibrium in aviation it refers to the initial response when disturbed from a given aoa slip or bankpositive static stability is the initial tendency of the helicopter to return to the original state of equilibrium after being disturbed dynamic stability dynamic stability refers to the helicopter response over time when disturbed from a given aoa slip or bankneutral dynamic stability means once displaced the displaced object neither decreases nor increases in amplitude a worn automobile shock absorber exhibits this tendencyfor information positive dynamic stability means over time the motion of the displaced object decreases in amplitude and because it is positive the object displaced returns toward the equilibrium state negative dynamic stability means over time the motion of the displaced object increases and becomes more divergent

Question 282-33 : Compared with usual values of a blade angle of attack the lift 1 and drag 2 in the stall change as follows ?

1 decreases 2 increases.

Question 282-34 : A strake on the tailboom is employed ?

To separate airflow downwash from the main rotor on one side of the tailboom.

2424on some helicopters running the length of the tail boom are 'l' shape brackets these are known as tail boom strakes and they act like spoilersthe strake breaks up the airflow downwash from the main rotor on one side creating a low pressure airflow past the strake the 'normal' higher pressure airflow on the unobstructed side of the tailboom thus turns the tailboom into a wing and creates lift toward the strake side of the boom this offloads the anti torque demand on the tail rotor giving greater tail rotor authority in the hover

Question 282-35 : An anti torque system without tail rotor is called ?

Notar.

2425notar fan housed in the aft fuselage pushes large amount of low pressured air into the tail boom the air is released through slits cut in the starboardright side of the tail boom and jet thruster the air released through the slits flows along the tail boon surface by a boundary layer control called coanda effectunder the effect of main rotor downwash tail boom acts like a wing and and produces lift toward right when observed from aft and this becomes a part of anti torque during hovering anti torque is compensated for with thrust generated by jet thruster

Question 282-36 : How are the speeds shown in the figure at point 1 and point 2 related to the relative windairflow v 2426 ?

V1 = 0 and v2 > v.

Question 282-37 : Which of these statements about tandem rotor helicopters are correct or incorrect 1 the two rotors turn in the same direction2 the rear rotor is positioned higher than the front rotor ?

1 is incorrect 2 is correct.

Boeing ch 47 chinook 1339vertol h 21 1340tandem rotor helicopters use counter rotating rotors with each canceling out the other's torque

Question 282-38 : When increasing the forward speed by a factor 3 the parasite power increases by a factor ?

27.

The parasite drag fx is the drag on the helicopter fuselage including the drag of the rotor hub and all external equipment as wheels winch etc the tail rotor drag is also included in the parasite drag the power to overcome this drag is the parasite power px fx = 12 rho s v² cxpx = fx x v = 12 rho s v3 cxpx varies as the cube of the speed

Question 282-39 : The si unit of power is ?

W.

Symbol is w unit is watt

Question 282-40 : The correct formula to calculate the tip circumferential speed nr revolutions per min and r rotor radius is ?

R x nr.