Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Basic Aerodynamics > Aerodynamics > Flashcards

Aerodynamics Flashcards

1
Q

What is aerodynamics?

A

The study of the properties of moving air and the interaction between the air and the solid bodies moving through it

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the continuity equation?

A

As speed increases, the cross sectional area decreases so long as density remains constant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the relationship between the velocity and the cross-sectional area in the continuity equation?

A

They are inversely proportional to one another

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Give the continuity equation formula

A

A1V1 = A2V2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the property of air in the subsonic region?

A

Incompressible

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Why is air incompressible in the subsonic region?

A

The flying body does not attain speeds necessary to compress the air

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

If there is no disturbance, air streamlines are what to one another?

A

Parallel to each other

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

When the diameter increases and speed decreases, what type of outlet is this classed as?

A

A diffuser outlet

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is a jet outlet?

A

An outlet where the diameter decreases and the speed increases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What does Bernoulli’s Principle state?

A

Total Pressure = Static Pressure + Dynamic Pressure

Total Pressure is always constant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

If the valve is closed, describe static, dynamic and total pressure

A

Static pressure is at its maximum
Dynamic pressure is 0
Total pressure is at its maximum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

As a valve starts to open, describe what happens in relation to pressure

A

Static pressure decreases as dynamic pressure increases

Total pressure remains at its maximum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the Point of Stagnation?

A

The point on the leading edge where dynamic pressure is 0 or the total pressure is equal to the static pressure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How do you calculate the total pressure?

A

Total pressure = Static Pressure + Dynamic Pressure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How is lift produced?

A

Higher pressure below the wing
Lower pressure above the wing
The difference in static pressure acts on the surfaces of the wing to create a lifting force

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is up-wash?

A

The upward flow of air directly ahead of the Leading Edge

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is down-wash?

A

The downward flow of air directly ahead of the Trailing Edge

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the Magnus Effect?

A

Mechanically induced circulation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Describe the pressure waves using the Magnus effect when the cylinder is stationary

A

Static pressure on the upper surface of the cylinder is equal to the static pressure on the lower surface
No differential pressure means no lift

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Describe the pressure waves using the Magnus Effect on a rotating cylinder

A

The circulatory flow causes an increase in local speed on the upper surface and a decrease in local speed on the lower surface
Difference in pressure generates lift

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

If the cylinder rotates at a higher speed, what happens to the pressure?

A

Decrease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What relation does speed have to pressure?

A

They are inversely proportional

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the general rule for vortices?

A

They come in a pair, clockwise and anti-clockwise

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is a wing profile?

A

A cross-section of a wing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What line connects the leading edge to the trailing edge?

A

Chord line

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Describe the mean camber line

A

The line drawn halfway between the upper and lower surfaces of the profile

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What is the displacement of the mean camber line from the chord line called?

A

Camber

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What is a maximum camber and where is it located in a typical low speed profile?

A

5% of the chord line

45% aft of the Leading Edge

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What is the fineness ratio?

A

The ratio of the length to diameter on a wing profile
Or
Maximum thickness as a fraction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What is the maximum thickness of a typical low speed profile and where is it located?

A

18% of the chord

30% aft of the Leading Edge

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What is the Flight Path Velocity?

A

The speed of the aircraft in a certain direction through the air

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What is relative wind?

A

The speed and direction of the air acting against the aircraft which is passing through it

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What does the relative wind depend on?

A

The flight velocity therefore it is not always horizontal

E.g banking

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What symbol is used for the angle of attack?

A

Alpha

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

What is the angle of attack?

A

The angle between the chord line and the relative wind

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

What is the angle of incidence?

A

The angle between the chord line and the longitudinal axis of the aircraft

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

What is the symbol used for the angle of incidence?

A

Gamma

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

What is the wing area?

A

The projection of the outline on the plane of the chord

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

What does the wing area include?

A

The fuselage between the wings

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

How do you calculate the wing area?

A

Wing span x average chord

b x c

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

What is the taper ratio?

A

The ratio between the tip chord and the root chord

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

How do you calculate he taper ratio?

A

Tip chord / root chord

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

What symbol is given to the taper ratio?

A

Lambda

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

What is the average chord?

A

The geometric average of all the chords

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

What is the aspect ratio?

A

The ratio between the wing span and the average chord

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

How do you calculate the aspect ratio?

A

Wing span / average chord

b / c

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

What is another way to calculate the aspect ratio?

A

AR = b^2/A

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

What is the meaning of a high aspect ratio?

A

It has longer and narrower wings

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

What is the angle between the line 25% chord and a line perpendicular to the root chord known as?

A

Sweep angle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

What is dihedral?

A

The increase of the angle attack for lateral stability

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

What is a positive dihedral wing?

A

When the wing tips are higher than the wing base

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

What is a negative dihedral wing known as and what are they?

A

Anhedral

When the wing tips are below the wing base

53
Q

What is the span wise flow?

A

The air flow that moves from the leading edge to the trailing edge

54
Q

Airflow flowing what to the chord line accelerates?

55
Q

What are some disadvantages of a swept wing?

A

Reduce amount of lift produced for a given flight speed, wing area and angle of attack
Contribute to drag

56
Q

What are some advantages of a swept wing?

A

Designed to fly close to or above the speed of soung

Provides stability

57
Q

What does a small dihedral allow?

A

More manoeuvrability

58
Q

Give the 2 aerodynamic forces

A

Lift and drag

59
Q

What is the center of pressure?

A

The point at which all pressures and forces act on

60
Q

What do lift and drag depend on?

A

Shape of the aerofoil
Angle of attack
Surface area
Dynamic pressure

61
Q

Give the equation for theoretical lift

A

Dynamic pressure x surface area

62
Q

What is the coefficient of lift?

A

Measured lift/ theoretical lift

63
Q

What is the coefficient of drag?

A

Measured drag / theoretical drag

64
Q

Why can one not rely on only the theoretical lift?

A

Too many variables changing

65
Q

If the measured lift is less than the theoretical lift, how do we account for the difference?

A

Introduce the Coefficient of lift to the lift equation

66
Q

What is the difference between the theoretical lift and the. Lift equation?

A

The lift equation includes the coefficient of lift which makes it more reliable

67
Q

What happens if the maximum angle of attack is exceeded?

A

Stall happens due to flow separation

68
Q

Two profiles have the same camber but different thickness. How are they affected by the Coefficient of lift?

A

Same coefficient of lift but at a lower angle of attack

Higher coefficient of like when the angle of attack exceeds 10 degrees

69
Q

Two profiles have the same thickness but different camber. How are they affected by the coefficient of lift?

A

Higher coefficient of lift at very low angle of attacks

Higher maximum coefficient of lift at lower maximum angle of attack

70
Q

What is the advantage/disadvantage of an aircraft flying at a high maximum Coefficient of lift?

A

Adv - aircraft able to fly slower

Disadv - may produce high drag and low critical mach

71
Q

How can ice on the surface be formed?

A

Change in temperature, pressure, density or humidity

72
Q

What effect can ice formation on the surface on the wing have?

A

Reduce maximum coefficient of lift and the maximum angle of attack if it forms on the LE

73
Q

Give the 2 dimensionless coefficients that can be combined to give information about the performance of profiles

A

Coefficient of drag

Coefficient of lift

74
Q

What is the Polar Diagram?

A

A lift vs drag graph which gives the best glide ratio

75
Q

What is needed in the Polar Diagram to find the angle for the best glide ratio?

A

Coefficient of lift

Coefficient of drag

76
Q

What is the meaning of the best glide ratio?

A

The best angle for the aircraft to fly efficiently

77
Q

What is induced drag?

A

Drag caused by lift

78
Q

What is the drag caused by pressure distribution known as?

79
Q

On a finite wing, what are the ends called?

80
Q

What happens on the wing tips of a finite wing?

A

Turbulence at the wingtips causes wingtip vortices

81
Q

What is the circulation around the profile causing upwash and downwash known as?

A

The bound vortex

82
Q

What does a finite wing have in comparison to an infinite wing?

A

Wing tip vortices and the bound vortex

83
Q

What is induced drag affected by?

A

Aspect Ratio
Speed of the aircraft
Wing tip design

84
Q

If the aspect ratio is high, what happens to the bound vortex and wing tip vortices?

A

They decrease

85
Q

What is the drag caused by skin friction known as?

A

Friction Drag

86
Q

What are the 3 types of Parasite drag?

A

Form
Friction
Interference

87
Q

What factors affect form drag?

A

Area of the wing

Aircraft speed

88
Q

What is the retarded air hitting the surface of the wing known as?

A

Boundary layer

89
Q

What is compressible drag?

A

Drag caused by shockwaves approaching the speed of sound

90
Q

What is compressible drag also known as?

91
Q

How do heavy birds reduce drag?

A

Use their feathers - act as wingtips

92
Q

What happens to an aircrafts angle of attack and lift coefficient during low speed and high speed flights?

A

Low speeds - higher angle of attack and lift coefficient

High speeds - lower angle of attack and lift coefficient

93
Q

What is used to reduce form drag on aircraft

A

Make the profile more streamlined

94
Q

What is the relationship between form and friction drag?

A

Inversely proportional

95
Q

How much is the form drag on the profile with the highest length to diameter ratio?

A

Has the lowest form drag but the highest friction drag

96
Q

What is the length to diameter ratio known as?

A

Fineness ratio

97
Q

What is friction drag?

A

Air particles that get trapped on the skin of the wing

98
Q

What is the boundary layer?

A

Where the air thickens and becomes retarded

Where the air moves from high pressure to low pressure areas and back again

99
Q

How is friction drag minimised?

A

Higher form

Making the skin surface smoother

100
Q

What are the two types of boundary layers?

A

Laminar

Turbulent

101
Q

Where is the laminar boundary layer located on the wing?

A

From the leading edge to the maximum thickness

102
Q

What does an increase in angle of attack do to the laminar boundary layer?

A

The laminar boundary layer comes earlier due to a faster airflow

103
Q

Which type of boundary layer encounters an energy exchange?

104
Q

How much friction is produced in the turbulent boundary layer compared to the laminar?

A

3x more than the laminar

105
Q

What are the roles of a slot in a profile?

A

To assist air particles reach high pressure areas at the trailing edge
To transfer air with the high energy to the lower side

106
Q

How can flow separation be prevented on the profile?

107
Q

What is interference drag?

A

Pressure caused by shockwaves

108
Q

How can we reduce interference drag?

109
Q

What is compressible drag?

A

Shockwaves formed by the aircraft approaching the speed of sound

110
Q

What is the cause of flow separation in the compressible drag?

A

Boundary layers thickening

Adverse pressure gradient across shockwaves

111
Q

What are the 4 different types of wing shapes?

A

Tapered
Rectangular
Square
Swept

112
Q

How is the wing designed so that the root can stall before the tips?

A

Geometric and aerodynamic twists

113
Q

What is the difference between the geometric and the aerodynamic twist?

A

Geometric twist - where the angle of incidence is greater at the root than the tip

Aerodynamic twist - where the camber is greater at the root than in the tip

114
Q

Where does the total wing lift act?

A

The center of lift

115
Q

What does MAC stand for?

A

Mean Aerodynamic Chord

116
Q

Where is the MAC located?

A

30% from the leading edge

117
Q

Where does the total weight of the aircraft act?

A

The center of gravity

118
Q

What happens if the position of the center of lift is the same as the center of gravity?

A

Straight and level flight

119
Q

When there is flow separation, at the root of the wing, where will the center of lift be?

A

In front of the center of cravity

120
Q

When does the aircraft experience a nose up reaction?

A

When the center of lift is in front of the center of gravity

121
Q

What is the device used on small aircraft to prevent the wing tip from stalling?

A

Stall strips

Vortex generator

122
Q

What is the disadvantage of the stall strip being mounted at the leading edge of the wing root?

A

Stall strips disturb lift

123
Q

What are slats used for?

A

Prevent wingtip stall on large aircraft

124
Q

What is span wise flow?

A

The air flow from the leading edge to the trailing edge

125
Q

What is the effect of span wise flow?

A

Boundary layer thickens towards the wing tip

126
Q

What are wing fences used for?

A

To keep the air particles in a straight line direction

127
Q

What are boundary layer fences?

A

Wing fences

128
Q

What is another device used to improve boundary layer control?

A

Saw toothed leading edges

Basic Aerodynamics (3 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions