Aerodynamics Flashcards
(127 cards)
1
Q
What is lift in aerodynamics?
A
Lift is the upward force that picks up the airplane from the ground.
2
Q
What is weight in aerodynamics?
A
Weight is the combined load of everything on the aircraft.
3
Q
What is the relationship between lift and weight in steady unaccelerated flight?
A
In steady unaccelerated flight, lift equals weight.
4
Q
What is thrust?
A
Thrust is the force which propels the aircraft forward.
5
Q
What is the formula for thrust?
A
Thrust = engine + propeller.
6
Q
What must thrust exceed for an aircraft to move forward?
A
Thrust must exceed drag.
7
Q
What is drag?
A
Drag is the force opposing the forward movement of the aircraft.
8
Q
What are the types of drag?
A
There are three types of drag: parasite drag, form drag, and skin friction drag.
9
Q
What is parasite drag?
A
Parasite drag is caused by the aircraft surface that disturbs airflow and interferes with the smooth airflow around the plane.
10
Q
What is form drag?
A
Form drag is the drag caused by wind that goes around the aircraft.
11
Q
What is interference drag?
A
Interference drag is turbulent airflow that occurs when different parts of the aircraft meet, such as where the wing meets the fuselage.
12
Q
What is skin friction drag?
A
Skin friction drag is caused by the surface of the aircraft at a microscopic level, where the surface may be bumpy and create resistance against the air.
13
Q
What is an Induced Drug?
A
A type of drug that is induced by certain conditions.
14
Q
What is induced drag?
A
Induced drag increases with airspeed and decreases with increased airspeed.
15
Q
What is total drag?
A
Total drag refers to the overall drag experienced by an aircraft at various airspeeds.
16
Q
What is the airspeed of least drag called?
A
The airspeed of least drag is called the lift-to-drag ratio (L/D).
17
Q
What is the airspeed of least drag for a Cessna 152?
A
60 knots.
18
Q
What is the airspeed of least drag for a Cessna 172?
A
48-70 knots.
19
Q
What does a plane need to create more lift?
A
To create more lift, a plane needs to increase its speed.
20
Q
What does Bernoulli’s principle state?
A
As the velocity of a fluid increases, the pressure decreases.
21
Q
How does an airfoil act?
A
An airfoil acts as a venturi, where faster air results in lower pressure.
22
Q
What happens to air pressure when airspeed increases?
A
Faster air results in lower pressure.
23
Q
What happens to air pressure when airspeed decreases?
A
Slower air results in higher pressure.
24
Q
What is the Bernoulli principle?
A
The Bernoulli principle states that as the speed of a fluid increases, its pressure decreases.
25
How can lift be increased?
Lift can be increased by increasing the airspeed, adding more thrust, or changing the shape of the airfoil.
26
What effect does increasing thrust have on lift?
Increasing thrust increases the amount of relative wind over the wings, leading to more lift.
27
What is the advantage of taking off and landing into the wind?
Taking off and landing into the wind maximizes relative wind, which increases lift.
28
How does changing the shape of the airfoil affect lift?
Changing the shape of the airfoil, such as increasing the camber, can increase lift.
29
What happens when you increase the camber of the airfoil?
Increasing the camber of the airfoil increases lift but also increases drag.
30
How can lowering flaps increase lift?
Lowering flaps increases camber, which provides more lift.
31
What is the relationship between angle of attack (AOA) and lift?
Increasing the angle of attack increases lift but also induces more drag.
32
How can you achieve more lift by adjusting the angle of attack?
Pointing the nose of the aircraft up increases the angle of attack, which strengthens lift.
33
What is a stall in aerodynamics?
A stall occurs when an aircraft rapidly loses lift.
34
What is the angle of attack (AOA)?
The AOA is the angle between the relative wind and the chord line.
35
What happens as the angle of attack increases?
As AOA increases, the air tends to bleed off the upper surface.
36
What is the boundary layer separation?
The air starts to separate, leading to boundary layer separation.
37
How does laminar flow affect lift?
A had laminar flow leads to less lift.
38
What happens when weight exceeds lift?
Once weight exceeds the lift-to-weight ratio, the plane will stall.
39
Do all aircraft have the same stall specifications?
Every aircraft will have different stall speeds and angles.
40
Does the angle of attack at which a plane stalls change?
The AOA at which a plane stalls will stay the same.
41
What factors can affect stall speed?
The stall speed can vary based on altitude and weight.
42
What is the critical angle of attack?
The maximum angle an aircraft reaches before stalling is called the critical angle of attack.
43
How do you recover from a stall?
To recover from a stall, you must reduce the angle of attack by pointing the nose down.
44
What is the recommended altitude for stall recovery practice?
All stall recoveries should be above 1,500 ft AGL.
45
What is the stall speed (VSO)?
The stall speed (VSO) will tell you your reference landing speed (Vret).
46
What is a spin?
A spin occurs in aggravated stall conditions mainly after mishandling the yaw control.
47
What is an aggravated stall?
An aggravated stall is when the lift is entirely lost, causing the plane to stall completely.
48
What happens when the yaw axis is mishandled?
The tail is misaligned with the plane's direction of travel.
49
What does 'the ball' or inclinometer indicate?
It indicates whether the aircraft is aligned on its yaw axis.
50
What can cause adverse yaw?
The plane can yaw due to uncoordinated ailerons.
51
What is uncoordination on the inclinometer referred to as?
It is referred to as 'skid'.
52
What does a skid indicate?
The ball on the left side indicates a skid.
53
How can you keep the tail coordinated with the airplane's direction?
Step on the ball by keeping it in the middle.
54
What should you do to avoid a spin?
Always break the stall first, then use P.A.R.E.
55
What does P.A.R.E. stand for?
P: Power Idle, A: Ailerons neutral, R: Rudder full opposite to the spin, E: Elevator down.
56
If an airplane spins to the right, which wing has stalled?
Both wings have stalled because when slipping or skidding, the plane can spin either way.
57
What is the lateral axis in airplane control?
The lateral axis is associated with pitch, allowing control of the airplane by pitching the nose up or down.
## Footnote
Controlled using the elevator via the yoke.
58
How do you pitch the airplane up or down?
You pitch the airplane up by pushing the yoke forward, which increases lift, or down by pulling the yoke backward, which decreases lift.
59
What is the longitudinal axis in airplane control?
The longitudinal axis is associated with roll, allowing control of which wing dips when the yoke is rotated.
## Footnote
One aileron is raised while the other dips, creating differential lift.
60
What is the vertical axis in airplane control?
The vertical axis is associated with yaw, controlling the airplane's side-to-side motion.
61
How is yaw controlled in an aircraft?
Yaw is controlled using the rudder pedals, which help maintain directional control.
## Footnote
'Stepping on the ball' can correct adverse yaw.
62
What happens when the plane rolls?
When the plane rolls, it creates adverse yaw, which can cause the plane to slip or skid.
63
What is stability in aircraft?
Stability is the ability of an aircraft to correct for disturbances and return to its original path.
64
What are the two types of stability?
The two types of stability are static stability and dynamic stability.
65
What is static stability?
Static stability is the initial tendency of the aircraft after a disturbance.
66
What is positive static stability?
Positive static stability is when the aircraft returns to its original path after a disturbance.
67
What is dynamic stability?
Dynamic stability is when the aircraft continues to climb after pitching.
68
What is dynamic stability?
Dynamic stability refers to an airplane's response to an upset over time.
69
What is positive dynamic stability?
In positive dynamic stability, plane oscillations stay the same.
70
What is neutral dynamic stability?
In neutral dynamic stability, plane oscillations remain unchanged.
71
What is negative dynamic stability?
In negative dynamic stability, oscillations increase over time.
72
What affects longitudinal stability?
The airplane's center of gravity is in front of the center of lift, which makes the nose heavy.
73
What role does the horizontal stabilizer play in longitudinal stability?
The horizontal stabilizer has a slightly negative angle of attack, creating a downward pressure.
74
What is lateral stability?
Lateral stability involves the dihedral effect and keel effect.
75
What is the dihedral effect?
When turbulence hits the underside of the wing, the plane will roll and enter a side slip or 'yaw'.
76
What is the keel effect?
The keel effect causes the aircraft to act like a pendulum when it rolls, wanting to swing back to level.
77
What is directional stability?
Directional stability is achieved through the weather vane effect, which helps align the aircraft.
78
How does the weather vane effect contribute to directional stability?
The weather vane effect helps push the tail back into alignment.
79
What happens to controllability as stability decreases?
Controllability decreases as stability decreases.
80
What can decrease stability beyond the limit?
Exceeding the limit can decrease stability and make controlling the aircraft difficult.
81
How does changing the angle of attack (AOA) affect controllability?
Changing the AOA can make the plane less controllable.
82
What factors affect the controllability of an aircraft?
The relative wind running over the control surfaces affects controllability.
83
What happens at faster airspeeds regarding control surfaces?
More air runs over the control surfaces, giving them more control authority.
84
What are the primary control surfaces of an aircraft?
Elevator, ailerons, and rudder.
85
What does the elevator control?
The elevator controls pitch.
86
What does the rudder control?
The rudder controls yaw.
87
What do spoilers do?
Spoilers help reduce lift and increase drag.
88
What is the purpose of trim systems?
Trim systems help regulate control systems.
89
In what order should the rudder and other controls be trimmed?
Rudder should be trimmed first, then elevator, and finally ailerons.
90
What do flaps do in aerodynamics?
Flaps increase lift and allow for a faster descent at a lower angle.
## Footnote
Example: Flaps down will increase lift.
91
What is the effect of flaps being up or extended?
Flaps up or extended allow for less drag and are used during cruise.
## Footnote
Example: Flaps up makes an airplane turn more efficiently.
92
What is the horizontal component of an airplane turn?
The horizontal component of an airplane turn is achieved by using the yoke or stick to enter a turn.
93
What happens when the aileron is deflected?
Deflecting the aileron creates more lift and more drag, which can lead to adverse yaw.
94
How can you counteract adverse yaw?
Use the rudder pedals to center the ball on the inclinometer.
95
What should you do to center the ball on the inclinometer?
Step on the ball.
96
What is Load Factor?
Load Factor refers to the ratio of the lift of an aircraft to its weight.
97
What is the formula for Load Factor?
Load Factor = Weight + Centrifugal Force
## Footnote
This is relevant when banking or turning.
98
What happens when you pull back on the yoke?
Pulling back on the yoke increases Angle of Attack (AOA), requiring more lift to overcome weight.
99
What are ways to increase Load Factor?
1. Increased bank angle
2. Increased speed
3. Descend
100
What is the consequence of increased Load Factor on aircraft?
Increased Load Factor leads to increased stress on the wings.
101
How is Load Factor calculated?
Load Factor is generally multiplied by the weight.
## Footnote
Example: 1 G = weight, 2 G's = weight x 2, 3 G's = weight + 3.
102
What is the significance of G-force limits?
Each aircraft has its G-force limit; exceeding this can cause structural damage.
103
What is the relationship between Load Factor and stall speed?
Higher Load Factor results in higher stall speed.
104
What can happen if you exceed the aircraft's G-force limits?
Exceeding G-force limits can lead to structural damage.
105
What is the coad factor measured by?
Coad factor is measured by 'G's'.
106
What is the total load in plane weights for 4,750 lbs in a 45 degree bank?
Total load = 1.5 × 1475183
## Footnote
45° bank = 1.5 G's
107
What is the total load of a 3,800 lbs plane in a 60 degree bank turn?
Total load = 2 × 3,800 lbs
## Footnote
60° bank = 2 G's
108
By how much does stall speed increase when banking 60°?
Stall speed increases by 42%.
109
What is calibrated airspeed?
Calibrated airspeed is an adjusted airspeed stated on a chart.
110
What is true airspeed?
True airspeed is airspeed that is adjusted for altitude and temperature.
111
What affects the airspeed indicator?
The airspeed indicator uses pressure to tell airspeed; lower pressure at higher altitude affects this.
112
What is ground speed?
Ground speed is how fast you are moving over the ground.
113
What is the left turning tendency in aerodynamics?
At high angles of attack, high power, and torque, the airplane tends to yaw to the left.
## Footnote
This is why in situations like a turn, you will need to compensate with right rudder.
114
What causes the left turning tendency?
One reason this tendency occurs is because of the torque reaction from the prop engine spinning.
115
What is P-factor?
P-factor occurs when you pitch the nose up because the downward moving propeller takes a bigger bite and causes the plane to yaw to the left.
## Footnote
P-factor is strongest at higher angles of attack.
116
What is the corkscrew effect?
The corkscrew effect occurs when the prop is moving slowly and the airplane spins to the left.
117
What are the takeaways regarding left turning tendencies?
The left turning tendencies include torque reaction, P-factor, and corkscrew effect. These effects are strongest at high angles of attack and low airspeed.
118
What are wing tip vortices?
Wing tip vortices are a byproduct of lift generated at the wing tips.
## Footnote
They are also known as wake turbulence.
119
What happens when a larger vortex is created?
A bigger vortex results in more induced drag.
## Footnote
Higher angle of attack leads to bigger vortices.
120
What is the Grand Effect?
The Grand Effect is a response to wing tip vortices in proximity to the ground.
## Footnote
It reduces vortices and makes lift more efficient.
121
How does proximity to the ground affect vortices?
Proximity to the ground reduces vortices and increases lift.
## Footnote
This can lead to longer takeoff distances.
122
What are the consequences of ground effect?
Ground effect increases induced drag, decreases stability, and increases indicated airspeed.
## Footnote
It affects low wing aircraft more than high wing aircraft.
123
What are wing tip vortices?
Wing tip vortices are a byproduct of lift generated at the wing tips.
## Footnote
They are also known as wake turbulence.
124
What happens when a larger vortex is created?
A bigger vortex results in more induced drag.
## Footnote
Higher angle of attack leads to bigger vortices.
125
What is the Grand Effect?
The Grand Effect is a response to wing tip vortices in proximity to the ground.
## Footnote
It reduces vortices and makes lift more efficient.
126
How does proximity to the ground affect vortices?
Proximity to the ground reduces vortices and increases lift.
## Footnote
This can lead to longer takeoff distances.
127
What are the consequences of ground effect?
Ground effect increases induced drag, decreases stability, and increases indicated airspeed.
## Footnote
It affects low wing aircraft more than high wing aircraft.
