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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
Whats the name of the stability of the aircraft with the pilot firmly holding the control column in place.
Stick fixed stability.
26
What type of stick stability is seen on a conventional aircraft?
Stick fixed stability
27
On an aircaft with fully powered flight controls, stick fixed stability X stick free stability ( <,>,=])
=
28
What type of stability is stick force per g.
Manoeuvre stability.
29
Which will produce a higher stick force per g? (Forward or aft CG)
Forward
30
Which will produce a higher stick force per g? (Low/high altitude(
Low
31
Stick force per g reduces as altitude increases due to blank blank being weaker.
Aerodynamic damping.
32
Longitudinal stability about the blank axis.
Lateral
33
Lateral stability about the blank axis.
Longitudinal.
34
Directional stability is stability in the blank.
Yaw
35
In longitudinal stability, an increase in blank should cause a pitch down ( -Cm)
AoA
36
In lateral stability, the aircraft should roll towards/away from the RAF.
Away.
37
In directional stability, the aircraft will yaw towards/away-from the RAF.
Towards
38
What does longitudinal stability depend on?
Angle of attack
39
If you have +Cm, which direction do you fly?
Pitch up
40
What angle determinals lateral stability?
Beta
41
What does -CL’ mean?
Roll left
42
What angle determines yaw?
Beta
43
What does CN mean for direction?
Turn right
44
If the CofG is forward of the aircraft, the wing is stabilising/unstabalising.
Stabilising
45
If the CofG is aft of the aircraft, the wing is stabilising/unstabalising.
Unstabalising
46
A fuselage mounted engine, compared to a wing mounted engine, is more or less stabilising?
More
47
When flaps are deployed, downwash increases. What happens to longitudinal stability?
Reduces
48
What is the static margic
A safety margin ahead of the neutral point
49
A forward cofg is like getting blank
Heavier
50
What CofG is the best in terms of stability.
Aft.
51
How long does a long period oscillation last? (Phugoid)
1-2mins
52
In a long period oscillation, which of the following are small changes and which are long (AoA/altitude/speed/loadfactor)
Small: AoA,n. Large: speed,altitude
53
How long does a short period oscillation last?
1-2 seconds
54
Is long or short oscillations more challenging for pilots to remove?
Short
55
A positive beta means a RAF from the ….
Right
56
Does a high wing increase or decrease lateral stability?
Increase
57
What is the keel surface?
Surface above the cofg height
58
A keel surface has a stabilising/unstabalising effect on lateral stability.
Stabilising
59
A stable aircraft rolls towards/away form relative airflow.
Away
60
A sweptback wing increases/decreases lateral stability
Increases
61
Does anhedral or diehedral reduce lateral stability?
Anhedral
62
A dorsal fin increases/decreases lateral stability.
Increases.
63
A ventral fin increases/decreases lateral stability.
Decreases.
64
For an airplane to always have positive longitudinal static stability the CG must be ahead/behind of the neutral point,
Ahead
65
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?
Down
66
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
23
67
Sensitivity for spiral dive will occur when: the static directional stability is positive/negative and the static lateral stability is relatively weak.
Positive
68
Dutch roll is the result of a strong (a)_____ lateral stability and a weak (b)_____ stability.
Static - static directional
69
The point between the aerodynamic centres of the wing and tail, where the…wing and tail moments are equal, is called the blank point
Neutral
70
An aeroplane with an excessive static directional stability in relation to its static lateral stability, will be prone to blank blank.
Spiral dive
71
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:
2
72
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.
Aerodynamic Damping.
73
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.
Later / decrease
74
An aeroplane which has low static lateral stability is more prone to have controllability problems in which two?: (roll/pitch/yaw)
Roll and yaw
75
If this aerodynamic centre is ahead of aircraft centre of gravity, as is usually the case, the effect is stabilising/destabilising.
Destabilizing
76
These are pitch oscillations at almost constant angle of attack with the exchange of an airplane’s kinetic (airspeed) and potential (altitude) energies.
Phugoid
77
The contribution of swept-back wings to static directional stability:
Positive
78
Moving the CG from an aft to a forward position during flight will: increase/decrease fuel consumption
Increase
79
CG towards the aft limit decreases/increases longitudinal static stability and decreases/increases pitch control forces.
Decrease
80
Moving the tailplane aft and increasing the surface will increase/decrease the negative CM for a given AoA.
Increase
81
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)
Neutral - positive
82
What is static stability
Short term
83
What is long term stability?
Dynamic

Principles Of Flight (24 decks)

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