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m8 > Aerodynamics And Theory Of Flight > Flashcards

Aerodynamics And Theory Of Flight Flashcards

1
Q

Linked to continuity what happens to air in the subsonic region?

A

Cannot attain speed to compress air (incompressible)

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2
Q

What does the continuity equation state?

A

Speed of airflow is inversely proportional to the area of cross section tube if density stays the same

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3
Q

What are the two types of outlet?

A

Jet
Diffuser

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4
Q

Total pressure =

A

Dynamic + static

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5
Q

Does the total pressure every change and explain your answer?

A

No it never changes, it’s split between dynamic and static

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6
Q

What is the point of stagnation?

A

Air velocity = 0

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7
Q

In the Venturi tube what happens as air flows through?

A

Accelerates until the thinnest point

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8
Q

As speed increases in the Venturi what happens to static and dynamic pressure?

A

Static pressure decreases and dynamic increases

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9
Q

What is the boundary layer?

A

Layer of air on the immediate surface and doesn’t move

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10
Q

What is laminar flow?

A

Moving air, known as laminate or turbulent

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11
Q

What is good about laminar flow?

A

It’s smooth and all airflow is parallel to each other

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12
Q

What is turbulent flow?

A

More naturally occurring disturbed flow

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13
Q

What is relative airflow?

A

Direction the natural air is going

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14
Q

The boundary layer can be either?

A

Laminar or turbulent

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15
Q

If the angle of attack increases what happens to the point at which air separates from the wing?

A

Moves forward

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16
Q

What are the advantages of laminar flow?

A

Less friction, better fuel usage, better range, faster speeds

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17
Q

What are the disadvantages of laminar flow?

A

Easier flow separation and easier stalling

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18
Q

What is up wash?

A

Airflow attracts to lower pressure region of the wing on the upside

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19
Q

What is downwash?

A

High pressure parts of aerofoil want to go to low pressure areas and once air has passed over aerofoil the pressure returns back to normal

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20
Q

What are vortices?

A

Disturbed airflow coming off the wing

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21
Q

What two edges does an aerofoil have?

A

Leading and trailing

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22
Q

What is the chord line?

A

Connects leading and trailing edge

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23
Q

What is the camber?

A

Chord line but drawn in equal distance from top to bottom

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24
Q

What is the aspect ration between on an aerofoil?

A

Length and average width

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25
Q

What are high aspect ratio wings used for?

A

Long span wings, used for gliders

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26
Q

What are low aspect ratio wings used for?

A

Shorter wings, used for military aircraft

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27
Q

What is induced drag affected by?

A

Aspect ratio, wing tip design, aircraft speed

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28
Q

What is wash in?

A

Angle of incidence is greater towards the tip

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29
Q

What is wash out?

A

Angle of incidence that is greater then the wing root

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30
Q

How can you ensure the root of the wing stalls first?

A

Geometrically twisting or washing out the wing

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31
Q

What is a geometrically twisted wing?

A

The camber is constant but the angle of incidence is greater at the root then the tip

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32
Q

What is an aerodynamically twisted wing?

A

The camber profile at the root is greater then the camber profile at the tip. Angle of incidence is constant

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33
Q

What does MAC stand for?

A

Mean aerodynamic chord

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34
Q

What does AOA stand for?

A

Angle of attack

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35
Q

Where is angle of attack measured?

A

Chord line to relative wind

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36
Q

Where is the angle of incidence measured?

A

Angle between chord and longitudinal axis

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37
Q

What does CP stand for?

A

Centre of Pressure

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38
Q

What are the 4 types of wing shape?

A

Elliptical
Rectangle
Tapered
Swept

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39
Q

Where does stall happen on an elliptical wing?

A

The entire wing

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40
Q

Where does stall happen on a rectangular wing?

A

Root to tip

41
Q

Where does a tapered wing stall first?

A

The tip

42
Q

Where does a swept wing stall first?

A

Tip

43
Q

Is a positive sweep forward or back?

A

Back

44
Q

Is a negative sweep forward or back?

A

Forward

45
Q

The more swept back a wing is where is the aircraft more stable?

A

In roll

46
Q

When is a wing known as dihedral?

A

When the wing tip is higher than the wing root

47
Q

What does a dihedral wing increase?

A

Lateral stability

48
Q

What makes a wing Anhedral?

A

The wing tips are lower than the wing root

49
Q

Drag is opposite to what force?

A

Thrust

50
Q

Total drag =

A

Induced drag + parasite drag + compressible drag

51
Q

Where is the low pressure and high pressure air on a wing?

A

Low pressure in above and high pressure is below

52
Q

During low speed flight is the AOA high or low?

A

High

53
Q

During high speed flight is the AOA high or low?

A

Low

54
Q

During low speed flight is the a high of low coefficient of lift?

A

High

55
Q

During high speed flight is there a high or low coefficient of lift?

A

Low

56
Q

What is form drag and what’s it caused by?

A

Parasite drag caused by pressure distribution

57
Q

What’s the relationship between form and friction drag?

A

A profile with low form drag has a high friction drag, and a profile with a high form drag has a low friction drag.

58
Q

What can interference drag be reduced by?

A

Different fairings on the aircraft

59
Q

When does compressible drag occur?

A

During transonic and supersonic flight

60
Q

For an aircraft to start moving what must exert drag?

A

Thrust

61
Q

To maintain constant speed what must be equal?

A

Thrust and drag

62
Q

What is the efficiency factor ratio between?

A

Thrust and drag

63
Q

What fundamental forces act on an aircraft?

A

Thrust, drag, lift, weight

64
Q

Why is lift produced?

A

Pressure difference above and below wing

65
Q

What is airflow separation also known as?

A

Stall

66
Q

What is stall define as?

A

Sudden loss in lift

67
Q

What is the usual critical angle?

A

15 degrees

68
Q

Is wing root stall or wing tip stall better?

A

Wing root stall

69
Q

How can we prevent wing tip stall on smaller aircraft?

A

Stall strip

70
Q

How can we prevent wing tip stall on larger aircraft?

A

Slats

71
Q

What are common aerofoil contaminations?

A

Dirt, snow, ice, dust

72
Q

What effect does ice on an aerofoil have?

A

Drag, extra weight, unbalancing

73
Q

What are the 3 main ice formations?

A

Rime ice
Clear ice
Frost

74
Q

When will frost form?

A

In clear air when the aircraft has been stored overnight in temperatures below 0

75
Q

When is rime ice formed?

A

Water droplets freeze when contacting a cold surface

76
Q

When is clear ice formed?

A

Flying in areas with large water droplets

77
Q

What is weight formed by?

A

Mass of the aircraft

78
Q

What must we produce to counteract weight?

A

Lift

79
Q

What forces pushes the aircraft through the sky?

A

Thrust

80
Q

What force resists the motion of the aircraft?

A

Drag

81
Q

What is used in the glide ratio?

A

Distance forward to distance downward

82
Q

What does AC stand for?

A

Aerodynamic centre

83
Q

What does CG stand for?

A

Centre of Gravity

84
Q

What must be equal to maintain contact speed in climb?

A

Thrust must equal drag and the rearward weight of the aircraft

85
Q

Is induced drag higher at low speeds of high speeds?

A

Low speeds

86
Q

What 2 forms does mechanical energy come in?

A

Kinetic
Potential Energy

87
Q

What is the load factor as a ratio?

A

Lift to weight

88
Q

Lift augmentations are useful why?

A

Systems installed to to produce more lift at certain speed, prevent low speed stalls

89
Q

What are the main lift augmentation devices?

A

Flaps
Slats and slots
Boundary layer control

90
Q

What are the types of flaps?

A

Plain flaps
Split flap
Slotted flap
Fowler flap

91
Q

What are the flaps and their increase in lift?

A

Plain - 50/55
Split - 60/65
Slotted - 65/70
Fowler - 95

92
Q

What do flaps change on the shape of the wing?

A

Increase camber

93
Q

Trailing edge flaps change what across the wing?

A

Pressure distribution

94
Q

What do Krueger flaps do?

A

Increase wings camber and generate more lift

95
Q

What do slats prevent?

A

Flow separation

96
Q

What is a slot?

A

Fixed aerodynamic feature on the wing

97
Q

What do cortex generators do?

A

Re-energise the boundary layer

98
Q

What do winglets do?

A

Prevent vortices on the tips of the wing that generate drag

99
Q

What are 4 benefits of installing winglets?

A

Fuel efficiency
Increased range
Performance
Lower emissions

m8 (3 decks)

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