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Question 280-1 : The maximum range speed for piston engine helicopters in zero wind conditions is found by ? [ Attainment AIM ]

Drawing a line tangential to the power required curve from the point of origin of the graph.

exemple 380 Drawing a line tangential to the power required curve from the point of origin of the graph. — . 1350.at the contact point, total drag is at a minimum, it gives the speed for maximum range.

Question 280-2 : With reference to rotor design, forward speed is limited by ?

Retreating blade stall and relative airspeed.

exemple 384 Retreating blade stall and relative airspeed.

Question 280-3 : A helicopter is most likely to encounter vortex ring under conditions of ?

Low airspeed with power, rate of descent greater than 300 ft/min.

exemple 388 Low airspeed with power, rate of descent greater than 300 ft/min.

Question 280-4 : In autorotation when aft cyclic is applied the effect will be ?

A decrease in airspeed and rate of descent.

exemple 392 A decrease in airspeed and rate of descent.

Question 280-5 : A stable static stability is ?

The tendency of an aircraft to return to its original condition of flight after a disturbance.

exemple 396 The tendency of an aircraft to return to its original condition of flight after a disturbance.

Question 280-6 : With a tail rotor positioned below the line of the main rotor, a helicopter at the hover will ?

Fly left side low if main rotor rotates anti clockwise viewed from above.

exemple 400 Fly left side low if main rotor rotates anti-clockwise viewed from above. — .a tail rotor positioned on the same line of the main rotor will reduce the.tail rotor roll.. 1352

Question 280-7 : Ground effect is caused by ?

A decreased induced flow velocity.

exemple 404 A decreased induced flow velocity.

Question 280-8 : In a still air hover induced flow velocity is affected by ?

Disc loading and density.

exemple 408 Disc loading and density.

Question 280-9 : What are the conditions necessary for ground resonance in addition to having a helicopter in contact with the ground ?

An out of balance force at the rotor head.

exemple 412 An out of balance force at the rotor head.

Question 280-10 : Dynamic roll over is ?

A condition whereby a rolling motion with wheels in contact with the ground cannot be restrained by cyclic control.

exemple 416 A condition whereby a rolling motion with wheels in contact with the ground cannot be restrained by cyclic control.

Question 280-11 : The minimum value of the power required curve determines ?

The t.a.s. for maximum rate of climb speed.

exemple 420 The t.a.s. for maximum rate of climb speed. — . 1356.at minimum value of the power required curve, where the gap between power available and the maximum power available is greatest, you will find the tas for maximum rate of climb speed.

Question 280-12 : In a level balanced turn ?

Retreating blade stall will occur at a lower i.a.s. than in straight and level flight.

exemple 424 Retreating blade stall will occur at a lower i.a.s. than in straight and level flight.

Question 280-13 : With forward flight, thrust on the advancing side of a tail rotor system ?

Is kept approximately constant because movement of the blade about its flapping axis reduces the angle of attack.

exemple 428 Is kept approximately constant because movement of the blade about its flapping axis reduces the angle of attack.

Question 280-14 : On a main rotor, if the flapping hinge is offset ?

It improves cyclic control response.

exemple 432 It improves cyclic control response.

Question 280-15 : The centre of pressure is the point on an aerofoil section ?

Through which the resultant aerodynamic force acts.

exemple 436 Through which the resultant aerodynamic force acts.

Question 280-16 : In autorotation the tail rotor thrust on a helicopter with anti clockwise main rotor rotation as seen from above is ?

To the left.

exemple 440 To the left. — .think back to basic vector diagrams of the main rotor. which way does total rotor thrust act answer = up...ok a tail rotor is exactly the same, just on its side. when we enter auto, we are removing all the torque from the main rotor. in an anti clockwise rotor, with power applied, this normally wants to spin us round to the right viewed inside the cockpit. that is what would happen if the tail rotor failed. remove tq and the fuselage is effectively now going to move in the opposite direction to the main rotor newtons laws equal and opposite blah it is not anywhere near as significant though, as there is no tq to really drive it, it is just trying to follow the main rotor, but there will be an amount of left yaw. the tail assembly design, will assist with directional stability in this instance, but we will still need a little extra help from the tail rotor...aircraft nose wants to go left or anti clockwise viewed from above, and tail wants to go right. we just need to counter this. remember here we have created a moment, and we need to balance it. as i said before, think about your vector diagram, and which direction does the thrust need to act up or in this case, the rotor is on its side, so to the left, in order to pull the tail back and push the nose back to the right...therefore we need a little thrust to the left to do this. the key is the fact that the aircraft wants to follow the main rotor once we have removed all the torque.

Question 280-17 : Induced power ?

Is a maximum at the hover without wind.

exemple 444 Is a maximum at the hover without wind.

Question 280-18 : In the flare, the resultant aerodynamic forces on the blades ?

Moves forward, towards the axis of rotation.

exemple 448 Moves forward, towards the axis of rotation.

Question 280-19 : The camber line of a biconvex symmetrical section is ?

Common with the chord line.

exemple 452 Common with the chord line.

Question 280-20 : The angle of attack of an aerofoil is the angle between ?

The chord line and the relative air flow.

exemple 456 The chord line and the relative air flow.

Question 280-21 : A reduction in blade section pitch angle towards the tip is termed ?

Washout.

exemple 460 Washout.

Question 280-22 : The force, which acts at right angles to the relative airflow, is ?

Lift.

exemple 464 Lift. — . 2413

Question 280-23 : The point at which the resultant of lift forces acts is ?

Centre of pressure.

Question 280-24 : On a symmetrical blade element with a positive angle of attack lift is produced by ?

Airflow velocity increasing over upper surface giving decreased pressure and velocity decreasing over lower surface giving increased pressure.

exemple 472 Airflow velocity increasing over upper surface giving decreased pressure and velocity decreasing over lower surface giving increased pressure.

Question 280-25 : Bernoulli's' theorem indicates that ?

The sum of pressure energy and dynamic energy is constant.

exemple 476 The sum of pressure energy and dynamic energy is constant.

Question 280-26 : The point where a laminar boundary layer becomes turbulent is called ?

The transition point.

exemple 480 The transition point. — .transition point the point on the surface of an aerofoil where laminar airflow becomes turbulent. the point moves forward as airspeed increases...the separation point point where airflow leaves the surface of an aerofoil.

Question 280-27 : The expression, 'in a streamlined flow of fluid, the sum of all energies is a constant,' derives from ?

Bernoulli's theorem.

exemple 484 Bernoulli's theorem.

Question 280-28 : Cl varies with ?

Angle of attack.

exemple 488 Angle of attack.

Question 280-29 : Within the normal operating angles of attack the centre of pressure of a biconvex symmetrical aerofoil section ?

Moves very little.

exemple 492 Moves very little.

Question 280-30 : That point where airflow leaves the surface of an aerofoil is known as ?

The separation point.

exemple 496 The separation point. — .the separation point point where airflow leaves the surface of an aerofoil...transition point the point on the surface of an aerofoil where laminar airflow becomes turbulent. the point moves forward as airspeed increases.

Question 280-31 : For a rotor which turns in an anti clockwise direction seen from above, with a sideways flight to the left, with zero wind, the pilot will have the advancing blade ?

In front of him

exemple 500 In front of him

Question 280-32 : The power requirement of the tail rotor is greatest during ?

A hover turn oge in the same direction as the main rotor

exemple 504 A hover turn oge in the same direction as the main rotor

Question 280-33 : 'a line connecting the leading and trailing edge midway between the upper and lower surface of a aerofoil'. this definition is applicable for ?

The camber line.

exemple 508 The camber line.

Question 280-34 : What is the effect on induced drag of an increase in aspect ratio ?

Induced drag decreases, because the effect of tip vortices decreases.

exemple 512 Induced drag decreases, because the effect of tip vortices decreases. — Induced drag varies with lift, speed and aspect ratio, is inversely proportional to aspect ratio and v² so multiply by 1/v² , and directly proportional to lift²/cl²/weight².

Question 280-35 : What is the stagnation point ?

The point where the velocity of the relative airflow is reduced to zero.

exemple 516 The point where the velocity of the relative airflow is reduced to zero.

Question 280-36 : When an aerofoil section has accelerated from subsonic to supersonic speeds, its aerodynamic centre will have ?

Shifted from approximately 25% to about 50% of the chord.

exemple 520 Shifted from approximately 25% to about 50% of the chord.

Question 280-37 : Which boundary layer, when considering its velocity profile perpendicular to the flow, has the greatest change in velocity close to the surface ?

Turbulent boundary layer.

exemple 524 Turbulent boundary layer.

Question 280-38 : The si unit of measurement for pressure is ?

N/m².

exemple 528 N/m². — .icao annex 5 units of measurement attachment b. 2. mass, force and weight.2.1 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 n/m² = pa , energy nm = j , and power nm/s = w.

Question 280-39 : The polar curve of an aerofoil section is a graphic relationship between ?

Lift coefficient cl and drag coefficient cd.

exemple 532 Lift coefficient cl and drag coefficient cd.

Question 280-40 : True airspeed tas is ?

Lower than the indicated airspeed ias at altitudes below sea level, under isa conditions.

exemple 536 Lower than the indicated airspeed (ias) at altitudes below sea level, under isa conditions. — .true air speed tas is obtained from indicated air speed ias by correcting for the following errors instrument, position, compressibility and density..so, tas is greater than ias with increasing altitude as density reduces...for this question, they state at altitudes below sea level , so it is reverse tas will be lower than ias density is higher for altitude below mean sea level...keep in mind that.ias is proportional to 1/2 rho tas².. rho = density.

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