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Question 281-1 : Total pressure is rho = density ? [ Attainment AIM ]

Static pressure plus dynamic pressure.

exemple 381 Static pressure plus dynamic pressure.

Question 281-2 : The unit of measurement for density is ?

Kg/m³.

exemple 385 Kg/m³.

Question 281-3 : The transition point is the point where ?

The boundary layer changes from laminar to turbulent.

exemple 389 The boundary layer changes from laminar to turbulent.

Question 281-4 : Considering a positively cambered aerofoil section, the pitching moment when the lift coefficient cl=0 is ?

Negative nose down.

.when a positively cambered airfoil is at zero lift it has to be at a small negative alpha to cancel out the camber, which gives some lift at zero alpha the angle of attack has a negative value when the lift coefficient equals zero..it is because the pressure distribution is producing negative lift at the front and positive lift at the back of the airfoil.. 1631.a symmetrical aerofoil need to have a positive pitch to produce lift. if the pitching moment is zero, the lift is zero..a positively cambered aerofoil produces lift with a zero pitching moment, thus, not to produce lift, it need a negative pitching moment.. 2416.in this example, lift coeffient = 0 when angle of attack = 4° the pitching moment is nose down. exemple 393 Negative (nose down).

Question 281-5 : An aerofoil is cambered when ?

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

exemple 397 The line, which connects the centres of all inscribed circles, is curved.

Question 281-6 : A flat plate, when positioned in the airflow at a small angle of attack, will produce ?

Both lift and drag.

exemple 401 Both lift and drag.

Question 281-7 : Positive static stability of an aeroplane means that following a disturbance from the equilibrium condition ?

The initial tendency is to return towards its equilibrium condition.

exemple 405 The initial tendency is to return towards its equilibrium condition.

Question 281-8 : Load factor is ?

Lift/weight.

exemple 409 Lift/weight.

Question 281-9 : Which statement is correct about an expansion wave in supersonic flow.1. the static temperature in front of an expansion wave is higher than the static temperature behind it..2. the speed in front of an expansion wave is higher than the speed behind it. ?

1 is correct and 2 is incorrect.

.the effect on pressure, temperature density and velocity is the opposite in expansion waves to oblique/normal shock waves... expansion wave.also known as a prandtl meyer expansion fan. when a supersonic airflow passes over a surface that suddenly drops away or rounds corner, an expansion fan of an infinite number of shock waves forms at the apex of the corner and diverts the airflow around the corner..airflowing through an expansion fan goes through the following changes..1.the airsteam accelerates, and the air behind the shock wave has higher supersonic velocity.2.the airflow direction follows the surface contour.3.the static pressure behind the expansion wave decreases.4.the density behind the expansion wave decreases.5.there is no loss of energy.. 2417. oblique/normal wave. 2418 exemple 413 1 is correct and 2 is incorrect.

Question 281-10 : Which rotor system is most effective in terms of control power ?

The rigidhead.

. 2405 exemple 417 The rigidhead.

Question 281-11 : What happens as a helicopter accelerates through 12 kt ?

It passes through translational lift.

exemple 421 It passes through translational lift.

Question 281-12 : With reference to translational lift, which of the following statements is true ?

Translational lift with associated reduction in induced flow and inflow angle becomes effective at about 12 knots

exemple 425 Translational lift with associated reduction in induced flow and inflow angle becomes effective at about 12 knots

Question 281-13 : When a helicopter is in an ideal free air hover the trt is acting vertically and is equal and opposite to ?

Weight and parasite drag.

..trt total rotor thrust..the parasite drag comes from the airflow blowing downwards over the fuselage. it adds to the apparent weight, so you need a little extra thrust to overcome it...looking at forward flight, you have four main vectors. 2419.as you slow down, and the downwash slowly changes from being rear and down to just being down, the vectors move around a little lift and weight stay the same, drag moves to being a bit down, and thrust has to move a bit up..in the hover, weight and drag coincide, and lift and thrust coincide, so in the hover you get.lift + thrust = weight + drag.

Question 281-14 : As a helicopter accelerates the attitude becomes ?

Nose down.

exemple 433 Nose down.

Question 281-15 : Where on the surface of a typical aerofoil will flow separation normally start at high angles of attack ?

Upper side trailing edge.

exemple 437 Upper side trailing edge.

Question 281-16 : Lift is the ?

Component of the total aerodynamic force, perpendicular to the undisturbed airflow.

.the component of the force perpendicular to the relative free stream i.e. undisturbed airflow is lift.

Question 281-17 : A helicopter is statically stable when it shows the ?

Tendency to return to its original attitude after having been displaced


Question 281-18 : Blade sailing can occur when ?

The rotor is starting up or slowing down in gusty wind conditions

exemple 449 The rotor is starting up or slowing down in gusty wind conditions

Question 281-19 : Which statement is correct regarding the coning angle ?

With increased rotor rpm the coning angle decreases

exemple 453 With increased rotor rpm the coning angle decreases

Question 281-20 : Dissymmetry of lift due to forward flight is compensated for by the ?

Advancing blade flapping up and reducing its angle of attack and the retreating blade flapping down and increasing its angle of attack


Question 281-21 : The rotor disc plane is always ?

Perpendicular to the rotor thrust

exemple 461 Perpendicular to the rotor thrust

Question 281-22 : The main induced air flow velocity is considered perpendicular to the ?

Tip path plane

exemple 465 Tip path plane

Question 281-23 : For a rotor which turns in a clockwise direction seen from above, in a backward flight, with zero wind, the pilot will have the advancing blade ?

On his right


Question 281-24 : For a rotor which turns in an anti clockwise direction seen from above, in a backward flight, with zero wind, the pilot will have the retreating blade ?

On his right

exemple 473 On his right

Question 281-25 : For a rotor which turns in a clockwise direction seen from above, in a backward flight, with zero wind, the pilot will have the retreating blade ?

On his left

exemple 477 On his left

Question 281-26 : Separation of the airflow from a blade ?

Occurs with increasing mach number at decreasing angle of attack.

exemple 481 Occurs with increasing mach number at decreasing angle of attack.

Question 281-27 : Drag dampers in a rotor system ?

May use the principle of damping by friction.

exemple 485 May use the principle of damping by friction.

Question 281-28 : The main reason for the negative range of tail rotor pitch is ?

For yaw control in autorotation.

exemple 489 For yaw control in autorotation.

Question 281-29 : Why is sweep back often applied to the tip of modern rotor blades ?

To reduce the mach effects on the advancing blade.

exemple 493 To reduce the mach effects on the advancing blade.

Question 281-30 : One reason for increased rotor rpm in the flare is ?

Conservation of angular momentum coriolis effect

exemple 497 Conservation of angular momentum (coriolis effect)

Question 281-31 : The advance angle is ?

Used to compensate for phase lag.

exemple 501 Used to compensate for phase lag.

Question 281-32 : The ground effect is affected by.1 the hover height.2 the length of the helicopter.3 the ground texture.4 the diameter of the main rotor.the combination of correct statements is ?

1, 3 and 4.

exemple 505 1, 3 and 4.

Question 281-33 : As a result of a positive 'g' manoeuvre in a helicopter there is ?

An increase in coning angle.

exemple 509 An increase in coning angle.

Question 281-34 : Drag dampers in a rotor system ?

May use the principle of damping by means of oil.

exemple 513 May use the principle of damping by means of oil.

Question 281-35 : The forces and moments caused by the dragging of the rotor blades on a hingeless rotor head are absorbed ?

Through bending at the blade root.

exemple 517 Through bending at the blade root.

Question 281-36 : The recommended recovery action from vortex ring settling with power is to ?

Cyclic forward to increase airspeed, pause for airspeed then apply power

exemple 521 Cyclic forward to increase airspeed, pause for airspeed then apply power

Question 281-37 : The centre of gravity of a single rotor helicopter will be ?

Close to the main rotor axis.

exemple 525 Close to the main rotor axis.

Question 281-38 : Drag damping may be achieved by means of ?

Oil or mechanical friction.

exemple 529 Oil or mechanical friction.

Question 281-39 : With regard to an intermeshing rotor helicopter synchropter.i. the full power available can be used for lifting..ii this helicopter has good directional stability. ?

I true, ii false.

. 1349.you do not have to counteract a torque reaction on a synchropter the two rotors turn in opposite directions..this arrangement allows the helicopter to function without the need for a tail rotor, which saves power. however, neither rotor lifts directly vertically, which reduces efficiency..yaw is accomplished through varying torque, which is done simply by increasing collective pitch on one of the blade sets, directional stability is not optimal. exemple 533 I true, ii false.

Question 281-40 : In a stationary hover relative to the ground , the position of the advancing blade relative to the pilot ?

Depends on the direction of rotation of the main rotor and wind direction.

exemple 537 Depends on the direction of rotation of the main rotor and wind direction.


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