POF – 10 Stability Part 1 ( Stability, Longitudinal & Trimming ) – LMS

Results

Q1. How can a pilot recognize static force stability in an aeroplane during flight?

When speed decreases, the push force increases

The elevator stick force remains constant with speed changes

To maintain a speed above the trim speed requires a push force

To maintain a speed above trim speed requires a pull force

Q2. A statically unstable aeroplane:

Will become stable at high speed

Reduces it's instability as the CG moves aft

Can never be dynamically stable

Is always dynamically stable

Q3. Longitudinal stability refers to movement about the:

Axis perpendicular on the vertical axis

Longitudinal axis

Lateral axis

Axis of the tail rotor

Q4. Positive static stability of an aeroplane means that once it has been displaced the:

tendency will be to move with an oscillating motion of decreasing amplitude

tendency will be to move with an oscillating motion of increasing amplitude

initial tendency to move is towards its equilibrium position

initial tendency to move is away from its equilibrium position

Q5. If an aircraft has static longitudinal instability, it:

will be dynamically stable

may or may not be dynamically stable, depending on momentum and damping factors

will be dynamically unstable

will be dynamically stable only at low speed

Q6. The effect of a highly cambered airfoil on longitudinal stability will be:

Positive effect because the lift vector is inclined rearwards as angle of attack increases

No effect

Negative effect because the lift vector is inclined forwards as angle of attack increases

Positive effect as CP moves backwards as angle of attack increases

Q7. If the aircraft has a nose up pitch displacement, the effective angle of attack of the tail plane:

remains the same

changes and causes the tail plan to apply a nose down moment

changes and causes the tail plane to apply a nose up moment

will not change if the pitch up was due to elevator selection

Q8. What will be the effect of a highly cambered aerofoil on longitudinal stability?

a negative effect because the lift vector is inclined forwards as the angle of attack increases

no effect

a positive effect because the lift vector is inclined rearwards as the angle of attack increases

a positive effect as the CP moves to the rear as the angle of attack increases

Q9. Which statement concerning longitudinal stability and control is correct?

A bob weight reduces the stick force per g

A down spring only improves the maneuver stability

A down spring has the same function as a stick pusher

A bob weight and a down spring have the same effect on the stick force stability

Q10. If an aeroplane exhibits insufficient stick force per g, this problem can be resolved by installing:

a bob weight in the control system that pulls the stick forwards

a bob weight in the control system that pulls the stick backwards

a spring that pushes the stick forwards

a spring that pulls the stick backwards

Q11. An aeroplane, with a C.G. location behind the centre of pressure of the wing can only maintain a straight and level flight when the horizontal tail loading is:

zero

upwards

downwards

upwards or downwards depending on elevator deflection

Q12. When an aeroplane with the centre of gravity forward of the centre of pressure of the combined wing/fuselage is in straight and level flight, the vertical load on the tailplane will be:

downwards because it is always negative regardless of the position of the centre of gravity

upwards

zero because in steady flight all loads are in equilibrium

downwards

Q13. When moving the centre of gravity forward, the stick force per g will:

Not change

Decrease

Increase of speed generates pull forces

Change, but only at very high speeds

Q14. What is the effect of an aft shift of the centre of gravity on(1) static longitudinal stability and(2) the required control deflection for a given pitch change?

(1) reduces; (2) increases

(1) increases; (2) increases

(1) increases; (2 reduces

(1) reduces; (2) reduces

Q15. When moving the centre of gravity forward the stick force per g will:

decrease

not change

increase

change but only at very high speeds

Q16. For a statically stable aeroplane: the relationship between the neutral point and the centre of gravity (CG) is such that the neutral point is located:

At the CG

Aft of the CG

Ahead of the CG

Anywhere, provided it is between the CG's forward and aft limits

Q17. The maneuverability of an aeroplane is best when the:

CG is on the aft CG limit

Flaps are down

CG position is on the forward CG limit

Speed is low

Q18. Longitudinal stability is directly influenced by:

Wing dihedral

The vertical stabilizer

Elevator deflection only

Centre of gravity position

Q19. Which CG position with respect to the neutral point ensures static longitudinal stability?

CG ahead of the neutral point

CG behind the neutral point

CG and neutral point in the same position

CG can be ahead of or behind the neutral point as long as the forward or aft CG limits are not exceeded

Q20. The CG of an aeroplane is in a fixed position forward of the neutral point. Which of these statements about the stick force stability is correct?

An increase of 10KT from the trimmed position at high speed has less effect on the stick force than an increase of 10KT from the trimmed position at low speed

Maintaining a steady speed below the trim speed requires a push force

Stick force stability is not affected by trim

Aeroplane nose down trim increases the stick force stability

Q21. The CG of an aeroplane is in a fixed position forward of the neutral point. Speed changes cause a departure from the trimmed position. Which of these statements about the force stability is correct?

Maintaining a steady speed above the trim speed requires a pull force.

An increase of 10 kts from the trimmed position at low speed has more effect on the stick orce than an increase of 10 kts from the trimmed position at high speed.

Aeroplane nose up trim decreases the stick force stability.

Stick force stability is not affected by trim.

Q22. The aft CG limit can be determined by the:

Minimum acceptable static longitudinal stability

Maximum elevator deflection available

Maximum static longitudinal stability required

Minimum acceptable elevator deflection

Q23. An aeroplane exhibits static longitudinal stability, if, when the angle of attack changes:

the change in total aeroplane lift acts through the centre of gravity

the change in total aeroplane lift acts aft of the centre of gravity

the resulting moment is positive

the change in wing lift is equal to the change in tail lift

Q24. The max aft position of the centre of gravity is amongst others limited by the:

too small effect of the controls on the aeroplane

maximum longitudinal stability of the aeroplane

maximum elevator deflection

minimum value of the stick force per g

Q25. The maximum aft position of the centre of gravity is, amongst others, limited by the:

Required minimum value of the stick force per g

Inability to achieve maximum rotation rate during take-off

Maximum longitudinal stability of the aeroplane

Maximum elevator deflection

Q26. For a normal stable aeroplane, the centre of gravity is located:

Aft of the neutral point of the aeroplane

With a sufficient minimum margin ahead of the neutral point of the aeroplane

At the neutral point of the aeroplane

Between the aft limit and the neutral point of the aeroplane

Q27. An aeroplane, with a CG location behind the centre of pressure of the wing can only maintain a straight and level flight when the horizontal tail loading is:

Upwards or downwards, depending on elevator deflection

Zero

Upwards

Downwards

Q28. The most forward CG location may be limited by:1) Insufficient flare capability.2) Excessive in-flight manoeuvrability.3) Insufficient in-flight manoeuvrability.The combination that regroups all of the correct statements is:

1,3

1,2

Q29. Longitudinal static stability is created by the fact that the:

wing surface is greater than the horizontal tail surface

centre of gravity is located in front of the leading edge of the wing

centre of gravity is located in front of the neutral point of the aeroplane

aeroplane possesses a large trim speed range

Q30. The (1) stick force stability and the (2) manoeuvre stability are positively affected by:

forward C.G. position (2) forward CG position

forward C.G. position (2) aeroplane nose up trim

aft C.G. position (2) aft CG position

aeroplane nose up trim (2) aeroplane nose up trim

Q31. A CG location beyond the aft limit can cause:

An unacceptably low value of the maneuver stability

A higher than normal stick force during normal take-off rotation

Improved spin recovery characteristics

in increase in static longitudinal stability

Q32. Which statement is correct?l) Stick force per g is independent of altitudell) Stick force per g increases when the centre of gravity moves forward

l is correct, ll is correct

l is incorrect, ll is correct

l is correct, ll is incorrect

l is incorrect, ll is incorrect

Q33. If an aircraft has its CG ahead of its CP, in straight and level flight:

there will normally be an upload on the tailplane

the tailplane will have a negative angle of attack

there will normally be a download on the tailplane

there will normally be no load on the tailplane

Q34. For a normal stable aeroplane, the centre of gravity is located:

aft of the neutral point of the aeroplane

with a sufficient minimum margin ahead of the neutral point of the aeroplane

at the neutral point of the aeroplane

between the aft limit and the neutral point of the aeroplane

Q35. The distance between the CG Datum and the CG Neutral Point in straight and level flight is called the:

CG forward limit

CG aft limit

CG static margin

CG manoeuvre margin

Q36. The effects of CG position on longitudinal static stability and control response will be:

forward movement of the CG will reduce stability and increase control response

forward movement of the CG will reduce control response and increase stability

rearward movement of the CG will increase stability and reduce control response

rearward movement of the CG will reduce stability and control response

Q37. The manoeuvrability of an aeroplane is best when the:

C.G. is on the aft C.G. limit

speed is low

C.G. position is on the forward C.G. limit

flaps are down

Q38. A C.G. location beyond the aft limit leads to:

a too high pulling stick force during rotation in the take off

an unacceptable low value of the manoeuvre stability (stick force per g. Fe/g)

an increasing static longitudinal stability

a better recovery performance in the spin

Q39. Moving the CG rearwards will:

have no effect on stability

increase lateral stability

increase longitudinal stability

reduce longitudinal stability

Q40. Where must the CG be located?

aft of the neutral point and in front of the manoeuvre point

between the aft limit and the neutral point

with sufficient margin ahead of the neutral point

on the neutral point

Q41. When an aircraft’s forward CG limit is exceeded, it will affect the flight characteristics of the aircraft by producing:

very light elevator control forces

higher stalling speeds and more longitudinal stability

improved performance since it reduces the induced drag

an extremely high tail down force

Q42. Forward and aft movement of the CG effect on stability and control will be:

rearward movement of the CG will reduce control and stability

rearward movement of the CG will reduce control and increase stability

forward movement of the CG will increase stability and reduce control

forward movement of the CG will reduce stability and increase control

Q43. In relation to the manoeuvre point, the aft CG limit is:

always forward of it

on the manoeuvre point

the least distance away when the CG is on the forward limit

aft of the manoeuvre point

Q44. Rearward movement of the CG will:

give increased tendency for spiral instability

increase Vmcg

give greater tendency to dutch roll

increase elevator stick force gradient

Q45. If an aircraft is longitudinally statically unstable, at the same time it will be dynamically:

unstable

neutral

stable

positively stable

Q46. What happens if CG moves behind the aft limit?

stick forces become excessive

lateral stability will be decreased

insufficient manoeuvre stability

longitudinal stability increases

Q47. The forward and aft CG limits are determined respectively by:

roll response, control forces

minimum control response, decreasing stability

dutch roll, increasing stability

control forces, increasing stability

Q48. Aft settings of the CG will:

increase the possibility of spiral instability

increase VMCG

increase the possibility of dutch roll

increase the elevator stick force gradient

Q49. When an aeroplane has zero static longitudinal stability, the Cm versus angle of attack line:

is horizontal

is vertical

has a negative slope

has a positive slope

Q50. During landing of a low-winged jet aeroplane, the greatest elevator up deflection is normally required when the flaps are:

UP and the CG fully forward

Fully down and CG is fully forward

Fully down and the CG is fully aft

Up and the CG is fully aft

Q51. During landing of a low-winged jet aeroplane, the maximum elevator up deflection is normally required when the flaps are:

fully down and the C.G. is fully forward

up and the C.G. is fully forward

fully down and the C.G. is fully aft

up and the C.G. is fully aft

Q52. The aerodynamic contribution to the static longitudinal stability of the nacelles of aft fuselage-mounted engines is

Maximum during cruise

Zero

Positive

Negative

Q53. The aerodynamic contribution to the static longitudinal stability of the nacelles of aft fuselage mounted engines is:

zero

negative

positive

maximum during cruise

Q54. A negative contribution to the static longitudinal stability of conventional jet transport aeroplanes is provided by:

a fixed trim position

the tail

the fuselage

a fixed elevator deflection

Q55. A negative contribution to the static longitudinal stability of conventional jet transport aeroplanes is provided by:

A fixed elevator deflection

The tail

A fixed trim position

The fuselage

Q56. The neutral point of an aeroplane is the point where:

The boundary layer changes from laminar to turbulent

The aeroplane becomes longitudinally unstable when the CG is moved beyond it in an aft direction

Assuming no flow separation the pitching moment coefficient does not change with varying angle of attack

The velocity of the relative airflow is reduced to zero

Q57. If the aircraft is properly loaded the CG, the neutral point and the manoeuvre point will be in the order given, forward to aft:

manoeuvre point, neutral point, CG

manoeuvre point, CG, neutral point

CG, neutral point, manoeuvre point

CG, manoeuvre point, neutral point

Q58. When the aircraft CG is on the aft limit, it is:

in front of the neutral point

above the neutral point

behind the neutral point

on the neutral point

Q59. What is the position of the CG in relation to the neutral point when the CG is on the aft limit?

on the neutral point

just behind the neutral point

above the neutral point

in front of the neutral point

Q60. If an aeroplane has poor longitudinal stability in flight, how can the stability be increased?

Installation of a yaw damper

Increased elevator range of movement

Increased stabilizer surface area

Reduced keel surface area

Q61. Which part of an aeroplane provides the greatest positive contribution to static longitudinal stability?

The horizontal tailplane

The fuselage

The engine

The wing

Q62. Positive static longitudinal stability means that a:

nose up moment occurs with a speed change at constant angle of attack

nose down moment occurs after encountering an up-gust

nose down moment occurs with a speed change at constant angle of attack

nose up moment occurs after encountering an up-gust

Q63. The air loads on the horizontal tailplane (tail loaof an aeroplane in straight and level cruise flight are generally directed:

Upwards and will reduce in magnitude as the CG moves aft

Downwards and will reduce in magnitude as the CG moves aft

Upwards and will increase as the CG moves aft

Downwards and will increase as the CG moves aft

Q64. Which part of an aeroplane provides the greatest positive contribution to the static longitudinal stability?

The engine

The horizontal tailplane

The fuselage

The wing

Q65. Which of the following components is most important in determining longitudinal static stability?

Fuselage

Wings

Engines

Horizontal tailplane

Q66. Which of the following components provides longitudinal stability?

engines

wing

fuselage

tail plane

Q67. As the stability of an aeroplane increases:

It's tendency to tuck under increases

It's maneuverability increases

There is no effect on its stability

It's maneuverability decreases

Q68. As the stability of an aeroplane decreases:

It's maneuverability increases

It's tendency to tuck under decreases

It's maneuverability decreases

There is no effect on it's stability

Q69. The C.G. position of an aeroplane is forward of the neutral point in a fixed location. Speed changes cause a departure from the trimmed position. Which of the following statements about the stick force stability is correct?

Increase of speed generates pull forces

Increasing 10 kt trimmed at low speed has more effect on the stick force than increasing 10 kt trimmed at high speed

Aeroplane nose up trim decreases the stick force stability

Stick force stability is not affected by trim

Q70. Stick force per g:

does not change with increasing altitude

is selected by the pilot by electronic means before each flight

is dependent on cg location

has a maximum value related to acceptable controllability, the minimum value is of no concern

Q71. Which statement about stick force per g is correct?

The stick force per g can only be corrected by means of electronic devices (stability augmentation) in case of an unacceptable value

The stick force per g increases, when centre of gravity is moved aft

The stick force per g must have both an upper and lower limit in order to assure acceptable control characteristics

If the slope of the Fe-n line becomes negative, generally speaking this is not a problem for control of an aeroplane

Q72. The magnitude of the stick force required to pitch, for an aircraft with manual controls, is determined by:

the distance the CG is forward of the neutral point

the distance the CG is forward of the static margin

the distance the CG is forward of the forward CG limit

the neutral stability

Q73. Which of the following statements is correct?l) A high limit load factor enables the manufacturer to design for a lower stick force per gll) The stick force per g is a limitation on the use of an aeroplane, which the pilot should determine from the Aeroplane Flight Manual

l is correct and ll is correct

l is correct and ll is incorrect

l is incorrect and ll is incorrect

l is incorrect and ll is correct

Q74. The stick force gradient is:

the force required to change the load factor of the aircraft a given amount

the force required to hold the aircraft in a particular pitch attitude

due to the dynamic pressure

only supplied by an artificial feel unit

Q75. The contribution of the wing to the static longitudinal stability of an aeroplane:

Depends on CG location relative to the wing aerodynamic centre

Depends on the wing location relative to the fuselage

Is positive if the wing has a positively cambered aerofoil section and the aerodynamic centre is ahead of the CG

Is always negative

Q76. Tuck under is:

the tendency to nose up when speed is increased into the transonic flight regime

the tendency to nose down when speed is increased into the transonic flight regime

shaking of the control column at high Mach Number

the tendency to nose down when the control column is pulled back

Q77. Speed stability of an aircraft:

is stable below Vmd because total drag decreases as speed decreases

is unstable above Vmd because thrust decreases as speed increases

is unstable below Vmd because total drag decreases as speed decreases

is stable above Vmd because total drag increases as speed increases

Q78. An aircraft is said to have speed stability:

if it recovers from displacements about any of the three axes at all speeds

if it can be trimmed to fly at any speed between stalling speed and Vne

when the speed is disturbed from its trimmed value, it tends to return to the original speed

if it can fly a 3-degree glide slope without the need to adjust the thrust setting

Q79. A symmetrical aerofoil section at CL = 0 will produce?

A negative (nose down) pitching moment

A positive (nose up) pitching moment

Zero pitching moment

No aerodynamic force

Q80. If the sum of moments in flight is not zero, the aero plane will rotate about:

the aerodynamic centre of the wing

the neutral point of the aeroplane

the centre of gravity

the centre of pressure of the wing

Q81. If the total moments about an axis are not zero, what will be the result around that axis?

Equilibrium

Constant angular velocity

Angular acceleration

Constant angular displacement

Q82. If the total sum of moments about one of its axis is not zero, an aeroplane:

would fly a path with a constant curvature

would be difficult to control

would experience an angular acceleration about that axis

would not be affected because the situation is normal

Q83. An aeroplane that tends to return to it’s pre-disturbed equilibrium position after the disturbance has been removed is said to have:

Neutral dynamic stability

Positive dynamic stability

Positive static stability

Neutral static stability

Q84. Positive static stability of an aeroplane means that following a disturbance from the equilibrium condition:

The tendency is to move with an oscillatory motion of decreasing amplitude

The initial tendency is to return towards its equilibrium condition

The tendency is to move with an oscillatory motion of increasing amplitude

The initial tendency is to diverge further from its equilibrium condition

Q85. Static stability means that:

Following a disturbance from the equilibrium condition, a force and/or moment is generated that tends to increase the effects of that disturbance

The amplitude of the oscillatory motion of an aeroplane tends to decrease over time

The amplitude of the oscillatory motion of an aeroplane tends to increase over time

Following a disturbance from the equilibrium condition, a force and/or moment is generated that tends to counter the effects of that disturbance

Q86. Following a disturbance, an aeroplane oscillates about the lateral axis at constant amplitude. The aeroplane is:

Statically stable - dynamically neutral

Statically unstable - dynamically neutral

Statically stable - dynamically unstable

Statically unstable - dynamically unstable

Q87. After a disturbance about the lateral axis, an aeroplane oscillates about the lateral axis at a constant amplitude. The aeroplane is:

Statically unstable – Dynamically neutral

Statically unstable – Dynamically stable

Statically stable – Dynamically unstable

Statically stable – Dynamically neutral

Q88. If an aircraft has negative dynamic and positive static stability, this will result in:

undamped oscillations

convergent oscillations

divergent oscillations

damped oscillations

Q89. If an aircraft is stable, this means that:

it is in a state of balance

all the stick forces have been trimmed out

if it is displaced it will return to its original position without any correction by the pilot

if it is displaced it must be returned to its original position by the pilot

Q90. The sum of the moments in flight are not zero, therefore movement would take place about:

the CG

the neutral point

the manoeuvre point

the CP

Q91. The CG of an aircraft with a nose wheel is:

forward of the main wheels

behind the main wheels

coincident with the nose undercarriage

in front of the nose wheel

Q92. Damping is the property that:

slows down the rate or diminishes the amplitude of vibrations or cycles

makes a body decelerate when thrust is reduced

requires an increased amount of energy to be used to accelerate a body when it approaches the speed of sound

makes an aircraft more stable at high altitude

Q93. Considering a positively cambered aerofoil section, the pitching moment when the lift coefficient: Cl=0 is:

positive (nose up)

equal to zero

maximum

negative (nose down)

Q94. Which of the following statements about dihedral is correct?

Dihedral is necessary for the execution of slip-free turns

Effective dihedral is the angle between the ¼-chord

Dihedral contributes to dynamic but not to static lateral stability

The effective dihedral of an aeroplane component means the contribution of that component to the static lateral stability

Q95. In a twin-engined jet powered aeroplane (engines mounted below the low wings) the thrust is suddenly increased. Which elevator deflection will be required to maintain the pitching moment zero?

Down

No elevator movement will be required because the thrust line of the engines remains unchanged

It depends on the position of the centre of gravity

Q96. In what way is the longitudinal stability affected by the degree of positive camber of the aerofoil?

Negative, because the lift vector rotates forward at increasing angle of attack

Positive, because the centre of pressure shifts rearward at increasing angle of attack

No effect, because camber of the aerofoil produces a constant pitch down moment coefficient, independent of angle of attack

Positive, because the lift vector rotates backward at increasing angle of attack

Q97. When an aeroplane with the centre of gravity forward of the centre of pressure of the combined wing / fuselage is in straight and level flight, the vertical load on the tailplane will be:

downwards

upwards

zero because in steady flight all loads are in equilibrium

downwards because it is always negative regardless of the position of the centre of gravity

Q98. An aeroplane, with a C.G. location behind the centre of pressure of the wing can only maintain a straight and level flight when the horizontal tail loading is:

upwards

zero

downwards

upwards or downwards depending on elevator deflection

Q99. Longitudinal dihedral is:

the difference between the wing and tail angle of sweep

the difference between the wing and tail angle of incidence

when the wing has anhedral and the tail dihedral

the difference between the wing and tail dihedral angles

Q100. In which situation would the wing lift of an aeroplane in straight and level flight have the highest value? (the engines are mounted below the wing)?

Forward centre of gravity and take-off thrust

Aft centre of gravity and idle thrust

Forward centre of gravity and idle thrust

Aft centre of gravity and take-off thrust

Q101. Considering a positive cambered aerofoil, the pitch moment when Cl=0 is:

negative (pitch-down)

equal to zero

infinite

positive (pitch-up)

Q102. On a symmetrical aerofoil, the pitch moment for which Cl=0 is:

zero

equal to the moment coefficient for stabilized angle of attack

positive (pitch-up)

negative (pitch-down)

Q103. When an aircraft pitches up, the angle of attack of the tailplane will:

remain the same

depend solely upon the rigger’s angle of incidence

decrease

increase

Q104. If the nose of an aeroplane yaws to port (left), this causes:

A roll to starboard (right)

A decrease in relative airspeed on the starboard (right) wing

An increase in lift on the port (left) wing

A roll to port (left)

Q105. Which statement in respect of a trimmable horizontal stabilizer is correct?

Because take-off speeds do not vary with centre of gravity location, the need for stabilizer adjustment is dependent on flap position only

An aeroplane with a forward cg requires the stabilizer leading edge to be lower than for one with an aft cg in the same trimmed condition

An aeroplane with a forward cg requires the stabilizer leading edge to be higher than for one with an aft cg in the same trimmed condition

At the forward C.G. limit, stabilizer trim is adjusted fully nose down to obtain maximum elevator authority at rotation during take-off

Q106. What is the effect of elevator trim tab adjustment on the static longitudinal stability of an aeroplane?

Depends on the value of stick force/g

No effect

Aeroplane nose up trim increases the static longitudinal stability

Aeroplane nose down trim increases the static longitudinal stability

Q107. A downward adjustment of a trim tab in the longitudinal control system, has the following effect:

the stick force stability remains constant

the stick position stability increases

the stick position stability remains constant

the stick force stability decreases

Q108. Upward deflection of a trim tab in the longitudinal control results in:

the stick position stability remaining constant

increasing the stick position stability

increasing the stick force stability

the stick force stability remaining constant

Q109. After an aeroplane has been trimmed:

The stick position stability will be increased

The stick force per g is reduced

The stick position stability will be unchanged

The trim tab will always be deflected in the same direction as the control surface itself

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