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Principles Of Flight > Stability > Flashcards

Stability Flashcards

1
Q

If you increase stability you decrease blank.

A

Manoeuvrability

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2
Q

Blank describes the a/c respondent disturbances to equilibrium.

A

Stability

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3
Q

Gust of wind and pilot inputs are types of blanks that move an aircraft away from equilibrium.

A

Disturbances.

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4
Q

What is static stability?

A

Initial response to a disturbance.

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5
Q

What is dynamic stability?

A

The response over time to a disturbance

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6
Q

An object has positive static stability when the direction of disturbance is in the direction of the blank position.

A

Equilibrium.

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7
Q

Blank static stability is when an object moves away from its equilibrium point.

A

Negative.

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8
Q

What does neutral static stability mean?

A

No initial reaction.

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9
Q

A displacement from equilibrium changing from positive to negative but reducing in size over time is a what type of dynamic and static?

A

Positive dynamic stability and positive static stability.

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10
Q

When something keeps oscillating either side pf equilibrium without a change in max displacement is a what type of dynamic stability?

A

Neutral.

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11
Q

What is negative dynamic stability?

A

Further and further from equilibrium each oscillation

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12
Q

When does negative static stability occur?

A

Object moving away from equilibrium point.

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13
Q

Moment = arm x blank

A

Force

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14
Q

What angle cause zero lift on a positively cambered wing?

A

-4

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15
Q

What is the absolute angle of attack?

A

The angle between the zero lift line and the relative airflow

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16
Q

What is the zero lift line?

A

RAF causes no lift.

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17
Q

What happens to lift when absolute angle of attack = 0?

A

Also equals zero

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18
Q

Where is the zero lift line on a symmetrical aerofoil?

A

Chordline

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19
Q

What is stick position stability?

A

Direction the elevator must be moved to change attitude,

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20
Q

The location of the wing centre of pressure (CP) forward or aft of the CG, influences the:

Blank moment and consequently the direction/magnitude of the stabiliser balancing force.

A

Pitching moment and consequently the direction of the stabiliser balancing force.

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21
Q

An aircraft will loose stuck position stability if it become blank statically unstable.

A

Longitudinally.

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22
Q

What happens to a wing’s critical angle of attack when it enters ground effect?

A

Decreases

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23
Q

Stick forces blank as the CofG moves forward and aft

A

Increase

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24
Q

Whats the name of the stability of the aircraft the pilot does not firmly hold the controls ?

A

Stick free stability

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25
Q

Whats the name of the stability of the aircraft with the pilot firmly holding the control column in place.

A

Stick fixed stability.

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26
Q

What type of stick stability is seen on a conventional aircraft?

A

Stick fixed stability

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27
Q

On an aircaft with fully powered flight controls, stick fixed stability X stick free stability ( <,>,=])

A

=

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28
Q

What type of stability is stick force per g.

A

Manoeuvre stability.

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29
Q

Which will produce a higher stick force per g? (Forward or aft CG)

A

Forward

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30
Q

Which will produce a higher stick force per g? (Low/high altitude(

A

Low

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31
Q

Stick force per g reduces as altitude increases due to blank blank being weaker.

A

Aerodynamic damping.

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32
Q

Longitudinal stability about the blank axis.

A

Lateral

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33
Q

Lateral stability about the blank axis.

A

Longitudinal.

34
Q

Directional stability is stability in the blank.

A

Yaw

35
Q

In longitudinal stability, an increase in blank should cause a pitch down ( -Cm)

A

AoA

36
Q

In lateral stability, the aircraft should roll towards/away from the RAF.

A

Away.

37
Q

In directional stability, the aircraft will yaw towards/away-from the RAF.

A

Towards

38
Q

What does longitudinal stability depend on?

A

Angle of attack

39
Q

If you have +Cm, which direction do you fly?

A

Pitch up

40
Q

What angle determinals lateral stability?

A

Beta

41
Q

What does -CL’ mean?

A

Roll left

42
Q

What angle determines yaw?

A

Beta

43
Q

What does CN mean for direction?

A

Turn right

44
Q

If the CofG is forward of the aircraft, the wing is stabilising/unstabalising.

A

Stabilising

45
Q

If the CofG is aft of the aircraft, the wing is stabilising/unstabalising.

A

Unstabalising

46
Q

A fuselage mounted engine, compared to a wing mounted engine, is more or less stabilising?

A

More

47
Q

When flaps are deployed, downwash increases. What happens to longitudinal stability?

A

Reduces

48
Q

What is the static margic

A

A safety margin ahead of the neutral point

49
Q

A forward cofg is like getting blank

A

Heavier

50
Q

What CofG is the best in terms of stability.

A

Aft.

51
Q

How long does a long period oscillation last? (Phugoid)

A

1-2mins

52
Q

In a long period oscillation, which of the following are small changes and which are long (AoA/altitude/speed/loadfactor)

A

Small: AoA,n. Large: speed,altitude

53
Q

How long does a short period oscillation last?

A

1-2 seconds

54
Q

Is long or short oscillations more challenging for pilots to remove?

A

Short

55
Q

A positive beta means a RAF from the ….

A

Right

56
Q

Does a high wing increase or decrease lateral stability?

A

Increase

57
Q

What is the keel surface?

A

Surface above the cofg height

58
Q

A keel surface has a stabilising/unstabalising effect on lateral stability.

A

Stabilising

59
Q

A stable aircraft rolls towards/away form relative airflow.

A

Away

60
Q

A sweptback wing increases/decreases lateral stability

A

Increases

61
Q

Does anhedral or diehedral reduce lateral stability?

A

Anhedral

62
Q

A dorsal fin increases/decreases lateral stability.

A

Increases.

63
Q

A ventral fin increases/decreases lateral stability.

A

Decreases.

64
Q

For an airplane to always have positive longitudinal static stability the CG must be ahead/behind of the neutral point,

A

Ahead

65
Q

When an aircraft enters a spiral dive with the CG at the AFT limit, when the spiral dive is fully developed, which of the following pitch attitudes is most likely?

A

Down

66
Q

An airplane’s sideslip angle is defined as the angle between:

  1. lift vector
  2. speed vector
  3. x-z plane of symmetry
  4. normal axis
  5. horizontal plane
A

23

67
Q

Sensitivity for spiral dive will occur when: the static directional stability is positive/negative and the static lateral stability is relatively weak.

A

Positive

68
Q

Dutch roll is the result of a strong (a)_____ lateral stability and a weak (b)_____ stability.

A

Static - static directional

69
Q

The point between the aerodynamic centres of the wing and tail, where the…wing and tail moments are equal, is called the blank point

A

Neutral

70
Q

An aeroplane with an excessive static directional stability in relation to its static lateral stability, will be prone to blank blank.

A

Spiral dive

71
Q

Sweepback of a wing positively influences:

  1. static longitudinal stability.
  2. static lateral stability.
  3. dynamic longitudinal stability.

The combination that regroups all of the correct statements is:

A

2

72
Q

Considering the longitudinal stability of an aeroplane at a given IAS, why does the stick force per ‘g’ decrease with increasing pressure altitude? Due to reduced blank blank.

A

Aerodynamic Damping.

73
Q

Consider that the angle of attack of a swept-back fin in a sideslip is increased. What happens to the static directional stability? The fin will stall earlier/later due to the sweep angle but will also increase/decrease the directional stability.

A

Later / decrease

74
Q

An aeroplane which has low static lateral stability is more prone to have controllability problems in which two?: (roll/pitch/yaw)

A

Roll and yaw

75
Q

If this aerodynamic centre is ahead of aircraft centre of gravity, as is usually the case, the effect is stabilising/destabilising.

A

Destabilizing

76
Q

These are pitch oscillations at almost constant angle of attack with the exchange of an airplane’s kinetic (airspeed) and potential (altitude) energies.

A

Phugoid

77
Q

The contribution of swept-back wings to static directional stability:

A

Positive

78
Q

Moving the CG from an aft to a forward position during flight will:

increase/decrease fuel consumption

A

Increase

79
Q

CG towards the aft limit decreases/increases longitudinal static stability and decreases/increases pitch control forces.

A

Decrease

80
Q

Moving the tailplane aft and increasing the surface will increase/decrease the negative CM for a given AoA.

A

Increase

81
Q

An aircraft is trimmed so that after a disturbance in pitch, it starts an oscillatory motion that does not decrease over time. In this case, the aircraft has (1)_____ dynamic stability and (2)_____ static stability. (Positive/negative/neutral)

A

Neutral - positive

Principles Of Flight (24 decks)

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