Aerodynamics Flashcards
1
Q
Vector
A
a quantity that represents magnitude and direction. It is commonly used to represent displacement, velocity, acceleration, and force
2
Q
Displacement
A
the distance and direction of a body’s movement
3
Q
Velocity
A
speed and direction of a body’s motion (the rate of change of position)
4
Q
Acceleration
A
rate of a body’s change of velocity
5
Q
Force
How is calculated?
A
push or pull exerted on a body
Force is mass X acceleration
6
Q
A vector is represented by a(n)?
A
arrow. The length of the arrow represents the magnitude and the heading of the arrow represents the direction.
7
Q
Can vectors be added together?
A
Vectors may be added by placing the head of the first vector on the tail of the second and drawing a third vector from the tail of the first to the head of the second. This new vector is the resulting magnitude and direction of the original two vectors working together.
8
Q
Mass (m)
A
quantity of molecular material that comprises an object.
9
Q
Volume (v)
A
amount of space occupied by an object
10
Q
Density (ρ)
A
mass per unit of volume (Mass divided by Volume)
11
Q
Work (W)
How is calculated?
A
when a force acts upon a body and moves it
a scalar quantity equal to the Force (F) times the distance of displacement (s), or W = F × s
12
Q
Power (P)
A
rate of doing work or work done per unit of time (t)
or P = W / time
13
Q
Horsepower
A
a unit of measurement used to express the amount of power being produced. Horsepower is calculated by dividing the results of either power formula above by 550 (this is a unit conversion using the units of pounds, feet, and seconds)
14
Q
Weight (W)
A
force with which a mass is attracted toward the center of Earth by gravity
15
Q
Moment (M)
How is it calculated?
A
what is created when a force is applied at some distance from an axis or fulcrum, producing rotation about that point.
The distance from the axis or fulcrum to the point of force is called the Moment Arm
Moment = Force x Distance
16
Q
Energy
What are the two forms?
A
a scalar measure of a body’s capacity to do work. There are two forms of energy: potential energy (P.E.) and kinetic energy (K.E.). Total energy (T.E.) is the sum of potential energy and kinetic energy
Energy is required for work (W)
17
Q
Potential Energy (P.E)
A
the ability of a body to do work because of its position or state of being. Potential energy is a function of mass, gravity, and height (MGH)
18
Q
Kinetic Energy (K.E.)
A
the ability of a body to do work because of its motion. It is a function of mass and velocity
19
Q
Energy cannot be created nor destroyed but may be ____ from one form (potential or kinetic) to the other. This principle is called ____ of energy.
For example, if a T-6A is in level, unaccelerated flight at a constant altitude and airspeed, both kinetic and potential energy are ____ .If you were to push the nose over you would lose altitude (____ energy) but “transform” that altitude loss into increased airspeed (____ energy) (Figure 1-10).
A
transformed
conservation
constant
potential
kinetic
20
Q
What is Newton’s First Law called? What does it say?
A
The first law is the “Law of Equilibrium.”
“A body at rest tends to remain at rest and a body in motion tends to remain in motion in a straight line at a constant velocity unless acted upon by some unbalanced force.”
Describes inertia
21
Q
What is Newton’s Second Law? What does it say?
A
Newton’s second law is the “Law of Acceleration”:
“An unbalanced force acting upon a body produces an acceleration in the direction of the force that is directly proportional to the force and inversely proportional to the mass of the body.”
When the thrust of an aircraft is greater than its drag, the excess thrust will cause the aircraft to accelerate until the increasing drag equals thrust.
22
Q
What is Newton’s Third Law? What does it say?
A
Newton stated a third law, the “Law of Interaction.”
“For every action, there is an equal and opposite reaction.”
This law is demonstrated when the rearward force from an aircraft propeller’s prop wash causes an aircraft to thrust forward with an equal amount of force
23
Q
What are the three characteristics of air?
A
Pressure, Temperature, and Density
24
Q
Ambient static pressure
How does it change with altitude?
A
a measurement of the weight of an air column over a specific area.
As altitude increases, there are fewer particles in a given column of air, thus ambient static pressure is less because the column of air above you weighs less
25
Air density
How does it change with altitude?
the total mass of air particles for a given volume.
As altitude increases, the distance between particles is greater (fewer particles of air for a given volume). This means that as altitude increases, air density decreases.
26
Temperature
How does it change with altitude?
Temperature is the measure of the average kinetic energy of the air particles.
Air temperature decreases at a rate of 2 °C for every 1000 feet. This is called the average, or standard, lapse rate.
27
What does the General Gas Law describe?
relationship between four basic atmospheric properties
(P) Pressure
(ρ) Density
(T) Temperature
(R) Universal Gas Constant
28
Fluid
any substance, liquid or gaseous, that has the ability to flow. Our atmosphere is a “gaseous fluid,” which means “airflow” is subject to the laws of fluid motion.
29
What are the three types of pressure?
Static pressure, dynamic pressure, and total pressure
30
Static Pressure (Ps)
the force that molecules of air exert on each other by their random movement
31
Dynamic Pressure (PD)
a measure of impact pressure of a large group of air molecules moving together
32
Total Pressure (PT)
sum of static and dynamic pressure
33
What 3 things must remain constant in a streamtube?
Mass, Total Energy, and Total Pressure
34
If the cross-sectional area on one side of streamtube decreases, what must increase so that mass flow remains constant?
Velocity
35
What are the 3 types of altitudes?
True altitude, Pressure altitude, and Density altitude
36
True altitude
actual height above mean sea level (MSL)
37
Pressure altitude
a height measured above a standard datum plane.
The standard datum plane is the actual elevation at which the barometric pressure is equal to 29.92 inHg which means on a standard day: pressure altitude = true altitude
38
Density altitude
pressure altitude corrected for temperature deviations from the standard atmosphere. Density altitude is not used as an actual “height reference” but rather as an index for gauging aircraft performance
39
On a standard day, what altitudes are equal?
All of them
True = Pressure = Density
40
What happens to aircraft performance as Density Altitude is increased? Why does this happen?
Performance will decrease
because less engine power is produced when fewer air molecules are available to burn and because a propeller creates less thrust when it has fewer air molecules to push aft.
41
A high DA requires ___ true airspeeds for takeoff and landing resulting in ___ takeoff and landing distances
higher and longer
42
True Airspeed (TAS)
the actual speed at which an aircraft moves through an airmass
43
Groundspeed (GS)
How does it compare to TAS?
the speed at which an aircraft moves relative to the ground.
It is true airspeed corrected for winds
44
Indicated Airspeed (IAS)
the speed that the pilot reads off the airspeed indicator
45
How does the airspeed indicator work?
The airspeed indicator shows dynamic pressure. It takes the total pressure of the air through the pitot tube and subtracts the static pressure from the static port to obtain dynamic pressure or IAS
46
The airspeed indicator is calibrated at the factory for standard day at sea level, where IAS equals TAS. What happens to TAS if IAS is held constant while climbing to a higher altitude?
Since air density decreases with an increase in altitude, TAS increases if IAS is held constant while climbing to a higher altitude.
at a constant IAS, TAS increases approximately 3 knots for each 1,000 foot increase in altitude
47
Calibrated airspeed (CAS)
indicated airspeed corrected for either indicator error or for minor sensing errors caused by the location of the pitot-static system on an airplane (can be mostly ignored for subsonic airspeeds)
48
Equivalent airspeed (EAS)
calibrated airspeed corrected for errors caused by compressibility effects (can be mostly ignored for subsonic airspeeds)
49
Airfoil
a streamlined shape designed to produce lift as it moves through the air
50
Mean Camber Line
the major design feature of an airfoil. It is a line drawn from the leading edge to the trailing edge, halfway between the upper and lower surface of the airfoil
51
Chordline
an infinitely long straight line drawn through the leading and trailing edges of the airfoil
52
Chord
the segment of the chordline measured from the leading edge to the trailing edge
53
Root chord, Tip chord, and Average chord
The root chord is the chord at the wing root, and the tip chord is the chord measured at the wingtip. Average chord is the average of all chords from the wing root to the wingtip.
54
Camber
the curvature of the mean camber line of an airfoil. Camber is measured by finding the maximum distance between the mean camber line and the chord line.
55
Symmetric Airfoil
A symmetric airfoil has zero camber. The MCL and chord are the same. There is as much cross-section above the chord as below the chord, hence the term symmetric
56
Positively cambered Airfoil
A positively cambered airfoil has the MCL above the chord. There is more cross-section above the chord than below the chord. This cambered airfoil produces lift at zero angle of attack.
57
Negatively cambered Airfoil
A negatively cambered airfoil has the MCL below the chord. There is more cross-section below the chord than above the chord. You have probably seen negatively cambered airfoils on high-performance race cars.
58
Spanwise Flow
airflow that travels along the span of the wing, parallel to the leading edge
This airflow does not accelerate over the wing and therefore does not create liftC
59
Chordwise Flow
air that flows at right angles to the leading edge of the airfoil
Since it is the only flow that accelerates over a wing, it is the only airflow that produces lift
60
Pitch Attitude
the angle between the longitudinal axis of an airplane and the horizon
61
Flightpath
an aircraft's apparent motion through an airmass
62
Relative wind
the apparent motion of the air with respect to the motion of the aircraft. The relative wind is in the direction opposite the flightpath.
63
Angle of Attack (AoA)
the angle between the chordline of the airfoil and the relative wind
Do NOT confuse this with pitch attitude.
64
Angle of Incidence
the angle between the airplane’s longitudinal axis and the chordline of its wing
65
Dihedral Angle
The angle of the upslope or downslope of the wings when viewed from head on.
Upslope is considered dihedral, and a downslope or negative dihedral is called anhedral.
66
Wingspan
What is the T-6A's wingspan?
he distance from wingtip to wingtip
The T-6A wingspan is 33 feet 5 inches.
67
Wing area (S)
How is it calculated?
he apparent surface area of a wing within an outline of the wing on the plane of its chord. It is approximated by multiplying the wingspan (b) by the average chord (c)
68
Wing loading (WL)
the ratio of an aircraft’s weight to the surface area of the wings or WL = Weight / S.
69
Wing Taper
reduction in the chord for a given airfoil from the root to the tip, and is measured by dividing the tip chord by the root chord
70
What is the benefit of tapered wings?
Tapered wings provide reduced weight and increased structural stiffness compared to a rectangular wing.
71
Sweep Angle?
the angle between the quarter chord line (a line that is 25% of the chord and not parallel to the leading edge) and a line parallel to the lateral axis of the aircraft
72
The T-6A wing is both?
tapered and swept
73
Aspect Ratio (AR)
ratio of the wingspan (b) to the average chord (c)
74
What is an example of an aircraft with a high aspect ratio and an example of a low aspect ratio?
An aircraft with a high aspect ratio (35:1), such as a glider, would have a long slender wing
A low aspect ratio (3:1) indicates a short stubby wing such as an F-22
75
What 3 things define an airplane's Center of Gravity (CG)?
-where the 3 axes intersect
-where all weight is concentrated
-point which movements are measured
76
3 axis of rotation
Longitudinal/Roll/Ailerons
Lateral/Pitch/Elevator
Vertical/Yaw/Rudder
77
Aerodynamic center (AC)
the point where all aerodynamic forces are acting (also known as center of lift)
78
How is the aerodynamic center typically positioned compared to the center of gravity?
The aerodynamic center (AC) point is typically aft of the aircraft’s CG to provide improved longitudinal stability around the lateral or pitch axis.
79
Weight and balance is concerned with the position of the CG in reference to the?
mean aerodynamic chord (MAC)
if the aircraft CG is too far aft, there will not be enough elevator authority to maintain level flight (the airplane will want to continue to pitch up into an eventual stall). If it is too far forward the opposite happens
80
Mass/Volume represents?
Density
81
What is done when a force acts upon a body and moves it?
Work
82
Which of Newton’s Laws state that “a body at rest tends to remain at rest and a body in motion tends to remain in motion...unless acted upon by some unbalanced force”?
Law of Equilibrium
83
The measurement of the average kinetic energy of air particles is called
Temperature
84
*******(True/False) Dynamic pressure is the measurement of force that molecules exert on each other in a still fluid.*******
True (need clarification for this one)
85
In a streamtube, where is the greatest total pressure?
The total pressure is the same everywhere
86
As the area of the streamtube decreases?
Velocity increases
87
A higher than standard day density altitude will do what to the takeoff roll?
increase takeoff roll (and decrease climb performance)
88
(T/F) Groundspeed is indicated airspeed corrected for winds.
False. Groundspeed is TRUE AIRSPEED corrected for winds
89
True Airspeed (TAS) must ____ as you climb in altitude with a constant indicated airspeed (IAS)
increase by ~3 knots per 1000 feet
90
The apparent motion of the air with respect to the motion of the aircraft is defined as the
Relative wind
91
Angle of Attack is the angle between the
relative wind and chordline
92
What is the benefit of a tapered wing?
Structural stiffness
93
What kind of aircraft have a very high aspect ratio?
Gliders
94
Having a CG that is too far aft causes the aircraft to exhibit
a tendency to pitch up into a stall
95
What is the point from which movements in roll, yaw, and pitch axes are measured
Center of gravity
96
The axis about which the airplane’s nose moves up and down is the
lateral or pitch axis
97
What is created when a force is applied some distance from an axis, producing rotation
Moment
98
Mass per unit volume defines?
Density
99
The ability of a body to do work due to its position or state of being
Potential energy
100
"For every action there is an equal and opposite reaction."
The Law of Interaction
101
True airspeed will be ____ indicated airspeed at 10,000 feet altitude.
greater than
102
What is a measure of the wing along the chordline, from the leading edge to the trailing edge?
the chord
103
Air density is ____ at 10,000 feet compared to 5,000 feet
lower
104
Altimeter setting for a standard day? What altitudes are equal?
29.92; pressure altitude = true altitude (and DA if temp is standard)
105
What is the point at which all weight is concentrated?
Center of Gravity
106
What axis is where the aircraft nose moves left or right about the Cg?
Yaw
107
What are the four primary forces acting on an aircraft in flight?
Weight, Lift, Thrust, and Drag
108
Equilibrium
Absence of acceleration (an aircraft in SLUF)
109
Does an aircraft have to be in straight and level flight to be in equilibrium?
No. An aircraft can be climbing but not accelerating or decelerating. In a climb or descent, equilibrium occurs when lift equals the “perpendicular” component of weight and thrust is equal to the sum of drag plus the “parallel” component of weight.
This means that for equilibrium flight in a climb or descent, the thrust component must be greater in a climb or less in a descent than it is for unaccelerated level flight.
110
During the takeoff ground run, ___ exceeds ___ (and friction) and ___ exceeds ___
thrust exceeds drag (and friction) and weight exceeds lift
111
At liftoff, ___ exceeds ___. ____ still exceeds ____ as the aircraft accelerates.
lift exceeds weight; thrust still exceeds drag
112
Aerodynamic force
a force that is the result of pressure and friction distribution over an airfoil (Lift and Drag)
113
The aerodynamic force acting perpendicular to the relative wind
Lift
114
The aerodynamic force acting parallel and in the same direction as the relative wind
Drag
115
The pressures acting on an airfoil are the result of
dynamic pressure (the air is being accelerated around the airfoil which decreases static pressure both above and below it)
116
On a positively cambered airfoil, the static pressure above the airfoil is
less than the static pressure below the airfoil. This differential pressure causes lift in the upward direction
117
What is the Lift equation?
Lift = Cl 1/2 p V^2 S
118
What three lift equation factors can a pilot control?
Velocity, Angle of Attack, and Shape (or camber)
119
What is the relationship between CL and AOA?
CL increases with increasing AOA until reaching CLMAX
The AOA that corresponds to CLMAX point is called the critical angle of attack
120
What happens if you increase aircraft AOA beyond the critical angle of attack?
a decrease in coefficient of lift due to boundary layer separation. This loss of lift is called a stall.
121
In straight-and-level flight, as angle of attack is increased, the pilot has to
decrease velocity to maintain level flight
122
Does a symmetric airfoil produce lift at 0 AoA? Why or why not?
No. Airflow over the top of a symmetric airfoil at zero degrees AOA travels the same distance as airflow over the bottom surface. This results in identical changes in static pressure both above and below the airfoil. Since no differential in pressure exists, no lift is produced.
123
Does a cambered airfoil produce lift at 0 AoA? Why or why not?
Yes. At zero degrees AOA, airflow over the upper surface of a positively cambered airfoil must travel a greater distance as compared to the bottom surface. This increased dynamic pressure results in a lower static pressure on the upper surface compared to the lower surface. The static pressure differential pulls the wing upward, creating a lift force
124
Aerodynamic twist
What does it do for an airfoil?
a decrease in camber from the wing root to the wingtip
Since a positively cambered airfoil stalls at a lower angle of attack, the wing root will stall before the wingtip.
125
Geometric twist
What does it do for an airfoil?
a decrease in the angle of incidence from wing root to wingtip. The root is mounted at some angle to the longitudinal axis, and the leading edge of the remainder of the wing is gradually twisted downward so that the angle of incidence at the wingtip is less.
Wing root is always at a greater AoA than the wingtip, thus stalling first
126
Does the T-6A have aerodynamic twist or geometric twist?
The T-6A has both aerodynamic twist and geometric twist.
127
Can drag ever be zero?
Because there is always some resistance to motion, drag can never be zero.
128
What are the two types of drag that combine to create total drag?
Parasite drag and Induced drag
129
Parasite drag
drag that is not associated with the production of lift
composed: Form, Friction, and Interference
increases as velocity increases
130
Form drag
What is it dependent on?
the separation of airflow from a surface and the wake that is created by that separation
The amount of form drag produced by an object is dependent upon the object's shape and size of its frontal area exposed to the relative wind
131
Friction drag
How can it be reduced?
caused by turbulent airflow in the boundary layer
Friction drag can be reduced by smoothing the exposed surfaces of the airplane through painting, cleaning, waxing, etc
132
How does keeping airflow in the boundary layer turbulent impact form and friction drag?
Keeping the airflow in the boundary layer turbulent makes it adhere to the surface better, reducing form drag with only a slight penalty in friction drag.
If the boundary layer were all laminar (smooth) airflow, it would easily separate from the surface creating a large wake behind the airfoil and increasing form drag.
133
Interference drag
How can it be reduced?
generated by mixing airstreams between aircraft components, such as the wing and fuselage
can be reduced by proper fairing and filleting to smooth out the point where the airstreams meet.
134
Induced drag
What is its relationship with velocity?
Induced drag is that component of drag that is associated with the production of lift.
As velocity increases, induced drag decreases. This is generally due to a lower angle of attack and the aircraft becoming more streamlined.
135
Why does induced drag happen?
Although the upwash and downwash created by chordwise flow are equal and counteract each other, some of the higher pressure air below the finite wing flows spanwise to the wingtip to try to equalize the pressure around the wing.
After the air flows up and around the wingtip, it mixes with the chordwise flow and creates additional downwash at the trailing edge.
Downwash is 2x greater than upwash
136
What factors increase induced drag?
Increased weight, decreased velocity, decreased wingspan, or decreased air density
137
What is a way to reduce induced drag?
Install devices to impede spanwise flow around the wingtip, such as winglets
138
Total drag curve is the combination of the parasite drag and induced drag curves. Is the total drag curve dependent on factors such as weight, altitude, or configuration?
Yes. These curves are plotted for a given weight, altitude, and configuration. Should any of these change, the curves would shift.
139
What is used to determine the efficiency of a wing?
The ratio of lift vs. drag (L/D)
140
At what point is L/D greatest? What is true at this point?
L/D Max
-Minimum total drag
-Parasite drag and induced drag are equal!!
-Greatest ratio of lift to drag (not maximum lift)
-The most efficient angle of attack for the wing
141
What is ground effect, when does it happen, and why?
Ground effect is a phenomenon that significantly reduces induced drag (Di) and increases effective lift when the airplane is within one wingspan of the ground. When the airplane is close to the ground, the downwash at the trailing edge of the wing is blocked by the ground and creates more effective lift and a "floating" sensation
142
What is Thrust Horsepower describing?
Propeller output
143
What is Shaft Horsepower describing?
Engine output
144
Propeller efficiency (p.e.)
The ability of a propeller to convert engine output (SHP) into thrust (THP)
p.e. = THP / SHP
145
Why is propeller efficiency never 100%?
friction in the reduction gearbox and drag from the propeller
146
What happens to all propellers as altitude or temperature increases?
They become less efficient because there is less air for the blades to bite and produce thrust
(a variable pitch propeller like the T-6A will increase blade angle to help minimize lost thrust)
147
In equilibrium flight, total thrust must equal total drag. Therefore, the thrust required graph is just?
an overlay of the total drag curve (where L/D Max is the same)
148
If you accelerate past L/D Max, what drag will increase at a greater rate? What if you decelerate?
Accelerate -> Parasite
Decelerate -> Induced
149
What is Thrust Available and why does it decrease with velocity?
Thrust available (TA) is the amount of thrust that is produced by an engine at a given PCL setting, velocity, and density.
A propeller can only accelerate air to a maximum velocity, so as the velocity of the incoming air increases, it is accelerated less by the propeller, resulting in a decrease in thrust available
150
What is thrust excess?
Thrust excess occurs if thrust available is greater than thrust required at a particular velocity
151
At maximum power, equilibrium flight is maintained when thrust available equals thrust required (where the 2 curves cross on the graph). What does this represent and what is it in the T-6A?
This is the maximum velocity in level flight that an airplane can achieve. It is 255 KIAS at sea level for the T-6A
152
What does a positive thrust excess cause? What about a lack of thrust excess?
A positive thrust excess causes a climb, acceleration or both depending on the angle of attack. A lack of excess thrust causes a descent, deceleration, or both depending on angle of attack.
153
Where is maximum excess thrust depicted on the graph and where does max excess thrust occur in a propeller-driven aircraft?
Maximum excess thrust is depicted on the graph where the distance between the TA and TR curves are the greatest.
For a propeller-driven aircraft, max excess thrust occurs at a velocity LESS THAN L/d max!!!
154
Power available (Pa)
the amount of power that an engine is producing at a given PCL setting, velocity, and density.
Maximum power available is produced at full PCL.
A propeller's PA initially increases but then decreases due to a loss of thrust available as velocity increases
155
How is Power Available calculated?
To obtain power (work/time), multiply thrust available by velocity and then divide by 325 to obtain horsepower.
156
Power Required (Pr)
the amount of power required to produce thrust required
157
Minimum power required for level flight
is at a SLOWER velocity than L/Dmax
158
Where does maximum excess power occur in a propeller-driven aircraft?
At L/DMAX!!!
159
How does weight change Pr and Tr?
Increased weight now means more lift is required to overcome that extra weight. To increase lift you either have to increase velocity or AoA. Either way, Pr and Tr increases with increased weight
160
How does altitude change Tr?
If the weight of an airplane remains constant, the lift required is the same at 20,000 feet as it is at sea level. But, to produce that same lift at 20,000 feet the velocity (TAS) must increase due to the decrease in air density. Therefore, TR must increase
161
How does altitude change Ta and Pa?
Maximum engine output decreases with decreased air density. So, both Thrust Available (TA) and Power Available (PA) decrease at higher altitudes
162
What happens when a pilot moves the stick to the right?
The right aileron raises to change the camber of that portion of the wing to that of a more symmetric airfoil – producing less lift.
The left aileron lowers, increasing camber on that portion of the left wing – producing more lift.
With less lift on the right wing and more lift on the left wing, the aircraft now rotates about the longitudinal axis to the right.
163
What happens when a pilot pulls the stick aft?
the trailing edge of the elevator goes up (making the tail go down) and the aircraft pitches up
164
What happens when a pilot steps on the left rudder pedal?
The rudder deflects to the left (making the tail move right) and the nose of the aircraft moves left
165
What happens when the camber of the wing is increased (via flaps or ailerons)?
The coefficient of lift increases, but the stall angle of attack decreases
166
What kind of flap does the T-6A use?
A split flap
167
Differentiate between the 4 different types of trailing edge flaps
Plain flap: increases camber of wing
Split flap: creates more drag than plain
Slotted flap: creates more lift and less drag than plain
Fowler: creates more lift and surface area
168
How do leading edge flaps differ to trailing edge flaps?
Both change the wing camber, but leading edge flaps create excessive drag at low angles of attack. However, at high angles of attack the air flow separation is delayed and stall speed is lowered
169
What advantage do flaps have on takeoff and landing?
Slower speeds and better visibility
Lowering the flaps increases lift allowing the aircraft to be flown at slower speeds for takeoff, approach, and landing. Also, a flatter pitch angle can be used during takeoff and landing, making it easier to see what is ahead.
170
50% flap setting
you gain more lift than drag (which is why its typically used for takeoff)
171
Lowering the landing gear causes an increase in what? What tendency does this give the aircraft?
Lowering the landing gear causes an increase in parasite drag from the gear and the gear doors. The aircraft has a tendency to pitch slightly down as the gear is lowered, and slightly up as the gear is raised.
172
Lift is defined as
component of aerodynamic force that acts perpendicular to the relative wind.
173
In straight-and-level flight (constant lift), angle of attack and velocity have __________ relationship.
an inverse
174
Which airfoil produces no lift at zero degrees angle of attack?
Symmetric
175
What is the benefit of geometric and aerodynamic twist on a wing?
The wing root stalls before the wingtip
176
Parasite drag is defined as drag
caused by anything other than the creation of lift.
177
Painting or cleaning the surface of a wing or aircraft will
reduce friction drag
178
Induced drag is caused by
the production of lift
179
In level flight, an increase in velocity will
decreased induced drag
180
Total drag is a combination of
induced drag and parasite drag
181
In relation to velocity, total drag
decreases until L/DMAX then increases.
182
Ground effect is the phenomenon that reduces __________ due to a decrease in __________
induced drag; downwash
183
Thrust is the force that opposes
drag
184
Thrust available __________ as velocity increases for a propeller-driven aircraft.
decreases
185
As velocity increases, a propeller's PA will initially increase then
decrease
186
To roll the airplane to the right, how do the ailerons move?
right aileron rises decreasing lift, and the left aileron lowers increasing lift
187
For the nose of the airplane to pitch up, the elevator must move where in relation to the horizontal stabilizer?
trailing edge of the elevator must move up in relation to the horizontal stabilizer
188
Increasing the camber of a wing increases?
lift
189
What kind of flaps does the T-6A have?
Split Flaps
190
Lowering the landing gear causes an increase in
Parasite drag
191
Aerodynamic force is the result of
pressure and friction distribution over an airfoil
192
Component of aerodynamic force that acts parallel to the relative wind is?
Drag
193
What kind of airfoil produces lift at zero degrees AoA?
Positively cambered
194
What is the point where the ratio of lift to drag is the greatest?
L/D Max
195
Total drag is comprised of?
Induced and Parasite drag
196
3 types of parasite drag?
Form, Friction, Interference
197
Maximum excess power for a propeller-driven aircraft occurs ____ L/DMax
At
198
As altitude increases, power available
decreases
199
Lowering the flaps to __________ during an approach __________ drag but __________ visibility.
landing (full); increases; improves
200
The minimum speed for takeoff is approximately __% above the power-off stall speed. That is a safety margin to avoid a stall immediately after takeoff.
20%
201
How can minimum takeoff speed be reduced? (3 ways)
Decreasing weight
Increasing wing surface area
Increasing CLMax
202
How can CLMax be increased for takeoff?
Flaps
203
Can flaps increase the surface area of the wing?
In some aircraft, yes, but NOT IN THE T-6A
204
What is the greatest factor in takeoff distance?
Weight!!
205
What 3 things are bad for takeoff performance?
Hot, Heavy, Humid
206
Why does a headwind decrease takeoff distance?
The aircraft will have a positive TAS before beginning the takeoff roll
207
Max Rate of climb
What does it rely on?
Gaining the most altitude in a given amount of time
Relies on excess power
208
Max Angle of Climb
What does it rely on?
Gaining the most altitude for distance traveled
Relies on excess thrust
209
Both max rate of climb and max angle of climb are flown at what power setting?
Maximum power
210
What is the best climb speed in the T-6A?
140 KIAS
211
What is the problem with max angle of climb?
an aircraft can be operating very close to stall airspeed. Fortunately, max angle of climb is not flown in the T-6A
212
What factors are directly linked to climb performance?
The ability to produce excess power or excess thrust (which encompasses weight/altitude/configuration)
213
How does a headwind or tailwind affect max angle of climb?
A headwind increases best angle of climb while a tailwind decreases best angle of climb
Here is an airplane that has a max angle of climb airspeed of 160 knots IAS. For this example, assume an initial no wind situation and that ground speed is also 160 knots. If this airplane flies into a headwind of 30 knots, its groundspeed is reduced to 130 knots. The airplane now reaches altitude in a much shorter ground distance.
214
How does a headwind or tailwind affect max rate of climb?
Wind does NOT change max RATE of climb
215
Maximum endurance
Maximum time that an airplane can remain airborne on a given amount of fuel
216
Where is maximum endurance for propeller aircraft?
SPEED LESS THAN L/D Max (a higher AoA, however) and on the Power Required (Pr) curve
217
Maximum range
the maximum distance an airplane can travel on a given amount of fuel
218
Where is a fixed pitch propeller airplane's max range?
L/D Max velocity and AoA
219
How does weight, altitude, and configuration impact cruise performance?
Weight: bad for cruise (more fuel needed to produce thrust)
Altitude: good for cruise (decreased temp = more efficient engine)
Configuration: bad for cruise (more drag requires more power)
220
How does wind effect maximum endurance?
Wind does NOT effect maximum endurance since maximum endurance is only concerned with time airborne and not distance traveled.
221
How does wind effect maximum range?
A headwind decreases and, conversely, a tailwind increases maximum range for a given amount of fuel. Maximum range is associated with a velocity, which in turn can be translated into a TAS. Therefore, a headwind reduces the aircraft’s groundspeed and hence the ground distance traveled for a given amount of fuel. A tailwind has the opposite effect.
222
Critical Mach Number
the Mach number that produces evidence of local supersonic flow
223
Mach number
ratio of the airplane's TAS to the local speed of sound
224
Can there be parts of an airplane where the airflow is supersonic even if the airplane is subsonic?
Yes. Since airplanes accelerate airflow to create lift, there is local airflow on parts of the airplane that are traveling faster than the airplane’s true airspeed. Normally, these are surfaces that have the most curvature, like the canopy or wing.
225
What is the best glide speed in the T-6A?
125 Knots
226
What is the ratio of the T-6A? What does this mean?
11:1 Glide Ratio
11,000 feet horizontally for every 1000 feet of altitude loss
227
What factors affect glide?
Altitude, wind, configuration, and propeller condition
228
Does weight impact maximum glide range?
No. As long as you are flying the L/D Max speed (which is faster for heavier aircraft)
229
What is the region of reverse command?
When you fly slower than L/DMAX in a turbojet or maximum endurance airspeed in a turboprop, you must increase thrust or power to maintain level flight
230
For landing, the final approach speed is usually __ times the stall speed?
1.3 times the stall speed (for safety)
231
What is the greatest factor in landing distance?
Weight!! (just like takeoff)
232
The 4 H's that affect takeoff distance also impact landing distance
High, Hot, Heavy, and Humid
233
Torque Effect
a reactive force based on Newton’s Third Law of Motion. This causes the aircraft to roll counterclockwise
primary means to compensate is: rudder and TAD
234
P-factor
yawing moment caused by one propeller blade creating more thrust than its opposing blade
235
What is required for P-factor to be noticeable?
High power setting and the thrust axis must be displaced from the relative wind
236
If you are pitched down, what rudder do you need to compensate for p-factor? What if you are pitched up?
Down -> Left rudder
Up -> Right rudder
237
Slipstream Swirl
corkscrewing airflow that travels around the fuselage (right rudder required)
238
When is slipstream swirl most prevalent?
High power settings and low airspeeds
239
Gyroscopic Precession
When you apply a force to the edge of a spinning object (propeller) parallel to the rotational axis, a resultant force is created in the direction of the applied force, but 90° ahead in the direction of rotation.
240
How does the T-6A help compensate for gyroscopic precession effects?
the TAD
241
What two factors are used to measure turn performance?
Turn radius: the radius of the circle that the flightpath defines
Turn rate: The rate of heading change measured in degrees per second
242
What two variables contribute to turn "performance"?
Velocity and Bank Angle
243
How is maximum turn rate and minimum turn radius achieved?
90º of bank and minimum velocity
244
Standard rate turns
3º per second (bank angle is dependent on airspeed)
245
If the ball is displaced in the direction of the turn, the airplane is in a "____." If the ball is displaced to the opposite direction of the turn, the airplane is in a "____"
Same direction of turn -> Slip
Outside direction of turn -> Skid
246
How is turn radius and turn rate altered in a slip vs. skid?
Slip: bigger radius and slower rate
Skid: smaller radius and faster rate
247
What is the hazard with skids?
Skids are dangerous due to the possibility that the airplane could roll inverted and even crash if a stall (skidded turn stall) occurs at low altitude.
248
How many G's are required to maintain 60º of bank in level flight?
2.0 G's
249
Limit load factor
greatest load factor an airplane can sustain without risk of permanent damage
250
Ultimate load factor
maximum load factor an aircraft can withstand without structural failure (150% of limit load factor)
251
Symmetric G's
anytime the only control deflected is the elevator
252
Asymmetric G's
encountered anytime the ailerons or rudder are deflected in flight, or there is a yawing moment produced by uneven weight distribution
253
Why are lower limits imposed for asymmetric G's?
These lower limits are imposed because the lift (G-force) on the up-going wing is more than what is read on the cockpit accelerometer
254
Aerodynamic (Stall) Limit
The curved lines that start at zero and intersect the load limit lines are called stall or aerodynamic limit lines. These lines represent the total load factor that can be generated at a particular airspeed before a stall occurs.
255
Maneuvering Speed (and what is it for the T-6A)?
the speed above which full or abrupt control movements in one axis can result in structural damage to the aircraft. The T-6A maneuvering speed limit is 227 KIAS.
256
Static stability
initial tendency of an object to move toward or away from its original equilibrium position
257
Dynamic stability
position and measure of displacement of an object after it has been disturbed with respect to time
258
Positive static stability
initial tendency of an object to return to its original equilibrium is positive static stability. A ball, when displaced in the bottom of a bowl, wants to roll back to the bottom where it started
259
Negative static stability
the initial tendency of an object to move away from its original equilibrium. Take the ball in the previous example, and turn the bowl upside down. The ball will now roll away from its original center point, exhibiting negative static stability.
260
Neutral Static Stability
the initial tendency of an object to accept the new position as a new equilibrium. If the ball is placed on a flat surface, and moved, it does not move toward or away from its originating position
261
Static vs. Dynamic Stability
Static stability only tells you about an object’s initial tendency for movement. It does not indicate whether the object will ever reach equilibrium (dynamic stability)
262
Positive dynamic stability
If the ball in the bowl moves through the equilibrium point when released, but each oscillation over time becomes smaller until it stops at the equilibrium point, it exhibits positive dynamic stability or damped oscillation
263
Negative dynamic stability
If the ball continued to climb higher on each pass, it would exhibit negative dynamic stability or undamped oscillation. This is very unlikely but airplanes sometimes exhibit this property.
264
Neutral dynamic stability
If the same ball’s oscillations never dampened but remained at a constant amplitude it would possess neutral dynamic stability
265
Stability vs Maneuverability
Stability and maneuverability are inversely proportional.
If an airplane is stable and tends to remain at equilibrium, it is hard for the pilot to turn the airplane, but easy to control (Cargo planes)
On the other hand, if an airplane is unstable it is easy to turn or maneuver but this responsiveness can make it hard to control otherwise (Fighters)
266
What two forces affect longitudinal static stability?
Lift and Weight (where CG is positioned vs AC)
267
Sideslip angle
difference between the flight path and the longitudinal axis
268
Factors that contribute to static stability
Straight wings: positive
Swept wings: positive
Fuselage: negative
Vertical stabilizer: positive
269
What is the greatest positive contributor to directional static stability?
Vertical stabilizer
270
What is the greatest positive contributor to lateral static stability?
Wing dihedral
271
How does wing mounting affect lateral stability?
High wing placement: positive lateral stability
Low wing placement: negative lateral stability
272
How does wing sweep and the vertical stabilizer effect lateral stability?
Both are positive contributors
273
What does cross-coupling mean?
Lateral and directional stability are interrelated
274
Directional divergence
An aircraft with directional divergence continues to yaw and increase its sideslip angle in response to a small initial sideslip
275
Spiral divergence
An aircraft that exhibits spiral divergence continues to yaw and roll in reaction to an initial sideslip, resulting in a tight descending spiral.
276
Dutch Roll
Dutch roll is caused by a combination of strong lateral and weak directional stability. A disturbance causes a roll that produces a sideslip. The airplane reacts with strong lateral stability by correcting to wings- level, but causing the nose to yaw in the direction of the sideslip. This cycle continues
277
Proverse Roll
Tendency for the aircraft to roll in the same direction as it is yawing
278
Adverse Yaw
tendency of the airplane to yaw away from the direction of aileron input. Due to increased lift on the up-going wing, more induced drag retards the forward movement of that wing, resulting in the nose yawing opposite the direction of roll
279
Phugoid oscillations
NOT a result of cross-coupling. Phugoid oscillations are long period oscillations (20 to 100 seconds per cycle) of altitude and airspeed while maintaining a nearly constant angle of attack. An upward gust causes an airplane to gradually gain altitude but lose airspeed. When enough airspeed is lost the airplane noses over and the reverse occurs. Usually a pilot corrects this situation without being aware that it is happening.
280
Which of the dynamic effects is NOT a result of cross coupling?
Phugoid oscillations
281
What are pilot-induced oscillations? Why do they happen? What axis do they normally occur in?-
Pilot induced oscillations are short period (1 – 3 seconds per cycle) oscillations that can occur in any three of the aircraft axes. The greatest hazard you face as a pilot is when it occurs in the pitch axis, particularly during landing. A PIO in the pitch axis is the result of the pilot and the inherent longitudinal stability of the airplane simultaneously trying to correct for the same oscillations.
282
What does the takeoff distance equation demonstrate?
Weight is the greatest factor in takeoff distance
283
Maximum range is defined as the
maximum distance an aircraft can fly on a given amount of fuel
284
Critical Mach Number is defined as the
Mach number that produces the first evidence of local supersonic flow
285
What speed give you the most distance for the airplane’s altitude if the engine fails?
Best glide speed (125 KIAS)
286
How will a headwind affect maximum glide range?
Decreases range
287
Is it possible to require more thrust for a slower airspeed?
Yes. This is known as the "region of reverse command"
288
Landing roll is decreased by what kind of wind?
Headwind
289
P-factor is caused by
one propeller blade creating more thrust thank its opposing blade
290
If the propeller rotates clockwise, what happens to torque?
torque is the opposite or counterclockwise
291
Turn rate and radius are based on what factors?
Velocity and bank angle
292
In a skid, the balance ball of the turn and bank indicator is deflected
in the opposite direction of the turn
293
Thrust must increase in a turn due to the increase in
drag
294
Load factor is the ratio of what?
Load to weight
295
What is limit load factor defined as?
the greatest load factor an airplane can sustain without risk of permanent deformation or damage.
296
Asymmetric G-limits are lower than symmetric because
the lift on the up-going wing is experiencing more Gs than what is read on the accelerometer
297
The G-force required to maintain a 60º bank level turn?
+2 G's
298
What is the initial tendency of an object to return to its original equilibrium?
Positive static stability
299
What is where oscillations never dampen but remain at a constant amplitude?
Neutral dynamic stability
300
An airplane exhibits __________ if after a disturbance that rolls the airplane, it generates forces that reduce the bank angle and return it to wings-level.
Lateral stabiity
301
Cross-coupling causes?
spiral and directional divergence
302
A PIO in the pitch axis is the result of the
pilot and the inherent longitudinal stability of the airplane simultaneously trying to correct for the same oscillations.
303
How does a tailwind impact takeoff distance?
Increases it
304
Max range is defined as the
farthest distance an airplane can travel on a given amount of fuel
305
Max endurance is
the maximum time that an airplane can remain airborne on a given amount of fuel
306
Max glide range (flown at best glide speed) is obtained at
L/D Max
307
Gaining the most altitude in a given amount of time is
max rate of climb
308
Slipstream swirl is most noticeable
high power settings and low airspeed
309
Ultimate load factor is defined as
the maximum load factor that the airplane can withstand without structural failure
310
Turn radius is a factor of?
Velocity and bank angle
311
Critical Mach is defines as
Mach number that produces the first evidence of local supersonic flow.
312
Sideslip angle is the
the difference between the flightpath and the longitudinal axis.
313
When flying at maximum endurance airspeed in the T-6A, increasing AOA to maintain level flight will result in _____ airspeed, requiring ____ power
Slower airspeed, requiring more power
314
What are the two types of flows in the boundary layer?
Laminar and Turbulant
315
What kind of flow is the primary producer of lift?
Laminar
316
What is the adverse pressure gradient? What causes it and what impact does it have?
Low pressure behind the max point of thickness creates turbulent flow
317
What is the boundary layer doing from the forward edge to the max point of thickness?
Laminar flow
Moving from high to low pressure
Airflow accelerates
Kinetic Energy builds
High boundary layer surface adherence
318
Boundary layer from Max point of thickness to trailing edge
Progresses from laminar to turbulent flow
Moving from low to high pressure
Airflow decelerates
Encounters adverse pressure gradient
Decreasing boundary layer adherence
319
What does a high AoA to the boundary layer?
Kinetic energy decreases, adverse pressure gradient increases, separation point moves forward
320
What is boundary layer separation?
Point in the streamline where airflow no longer adheres to the airfoil; caused by decreasing ratio of kinetic energy vs. adverse pressure gradient. As turbulent airflow area increases, amount of airfoil producing lift can become insufficient to support aircraft's weight.
321
What is a stall?
Condition in flight where increase in AoA results in decrease in CL
322
Stall AoA
remains constant for any airfoil
measured in arbitrary units
323
Stall speed
variable based on condition
324
Two classifications of stalls?
Power-on and power-off
325
What kind of stall will give a warning indication closer to stall airspeed?
Power-off
326
Where does the aircraft tend to roll in power-on v. power-off stalls?
Power-on: left (due to torque)
Power-off: right (due to engine mounting)
327
What does the vertical component of thrust do for stalls?
Lowers stall speed by essentially acting as lift
328
What factors affect stall airspeed?
Gross weight, Altitude (air density), and Load factor
329
Does true or indicated stall airspeed increase with altitude?
True
330
Why does increased G-loading affect stall airspeed?
It is equivalent to increased weight
331
What does boundary layer control devices do?
deflects high kinetic energy airflow from bottom of wing to top of the wing to suppress boundary layer separation
332
What is the most common boundary layer control device?
Leading edge slats
333
What are the benefits of boundary layer control?
Increased maneuvering capabilities and decreased landing speed/distance
334
What is the order that control effectiveness is lost?
Ailerons, elevator, rudder
335
How many AoA units does the T-6 stall at?
18 units
336
What stall warnings are available in the T-6A?
Turbulent airflow striking empennage, AoA Gauge, and Stick Shaker
337
What impact does the stick shaker have on natural stall warnings?
May mask aircraft buffeting
338
Describe laminar flow
Area of the boundary layer where air molecules flow smoothly within the streamline
339
What force opposes and controls the adverse pressure gradient?
The kinetic energy of the relative wind
340
What is the definition of boundary layer separation?
Point in the streamline where airflow no longer adheres to the airfoil
341
What is the point of stall on a CL curve?
CL Max
342
Definition of a stall
Condition in flight where increase in AOA results in decrease in CL
343
Key difference between stall AoA and stall airspeed?
Stall AOA remains constant – stall airspeed is variable
344
What are the factors associated with increased thrust that impact stall characteristics
Vertical thrust component and propeller acceleration factor
345
What are the two major classifications of stalls?
Power-on and power-off
346
Which type of stall will have the lowest stall airspeed?
Power-on stall
347
Which flight control would you normally expect to be least effective during a stall/stall recovery?
Ailerons
348
Would a heavier or lighter aircraft stall at a higher indicated airspeed?
Heavier
349
Would an aircraft at 12,000 feet or 6,000 feet stall at a higher true airspeed?
12,000 feet
350
How does G-loading affect stall speed?
stall speed increases
351
If maintaining level flight, what happens to stall airspeed as you increase bank angle?
stall speed increases b/c of increased load factor
352
What is the effect of increased weight on stall airspeed?
stall speed increases
353
Higher G-loading and higher bank angle = _____ stall airspeed.
Higher
354
What is the basic function of a boundary layer control (BLC) device?
to suppress boundary layer separation
355
What is the T-6A stall AOA?
18 units
356
What is the primary artificial stall warning in the T-6A?
stick shaker
357
What does activation of the stick shaker indicate?
aircraft is approximately 5 to 10 knots above stall speed
358
What effect does increasing AOA have on the kinetic energy of the relative wind?
decreases it
359
What are the benefits provided by Boundary Layer Control (BLC) devices?
Increased maneuvering capability
Decreased landing speed and distance
360
Which type of stall will have the lower stall airspeed?
Power-on stall
361
What is the only reason the T-6A will stall?
Exceeding stall AoA (18 units)
362
What is required to enter a spin?
Stall and yaw
363
What is post-stall gyration
Aerodynamic forces during a stall that result in movement around the pitch, roll, and yaw axes
364
How does airspeed at stall energy affect poststall gyration tendency?
Higher the energy (airspeed) at stall entry – greater the poststall gyration tendency
Lower the energy (airspeed) at stall entry – less the poststall gyration tendency
365
Autorotation
Combination of roll and yaw that propagates itself and progressively gets worse due to asymmetrically stalled wings
366
What does the introduction of yaw do when an aircraft is stalled?
When the aircraft is stalled, introduction of yaw creates an AOA difference between left and right wings.
Lift and drag become unbalanced
Creates rolling and yaw tendency
Can cause spin entry and autorotation
367
What does higher and lower AoA in a stall result in?
In a stall, lower AOA = more lift
Higher AoA = less lift
368
Which wing has a higher AoA in a spin?
The inside wing (which is why it is producing less lift)
369
How does AoA and drag correlate in a spin?
Higher AoA = more drag
Lower AoA = less drag
370
What sustains aircraft rolling motion around the spin axis?
Lift differential and drag differential
371
How does an inverted spin occur?
Entered from negative G stall and yaw
372
How does an erect spin occur?
Entered from positive G stall and yaw
373
How does lower pitch impact rotation rate in a spin?
Lower pitch results in higher rotation rate
374
How does the rotation rate affect nose-down movement?
Higher rotation rate results in larger force opposing nose-down movement
375
Why does steeper pitch and increased rotation rate occur?
Intentional or unintentional control inputs
Aircraft weight
Spin direction
376
Progressive spin
Caused by maintaining full up elevator while holding anti-spin rudder
Characterized by lowering of the nose and spin direction reversal
377
Aggravated spin
Caused by maintaining pro-spin rudder and moving stick forward of neutral
Characterized by immediate increase in nose-down pitch and increased roll rate
378
How does weight affect spin entry and recover?
Lighter = faster entry, increased oscillations, faster recovery
Heavier = slower entry, less oscillations, slower recovery
379
How does stall speed vary with pitch attitude?
Inversely
(Lower pitch attitude = higher stall speed and faster entry)
(Higher pitch attitude = slower stall speed and slower entry)
380
What are characteristics of a right spin?
Stabilizes at lower pitch
Stabilizes slower
Rotation rate increased
381
What are characteristics of a left spin?
Stabilizes at a higher pitch
Stabilizes faster
Rotation rate decreased
382
Can an aircraft that is not stalled be in a spin?
No. Both stall and yaw must be present to spin.
383
Define poststall gyration
Aerodynamic forces during stall that result in movement around the pitch, roll, and yaw axes
384
What is the key factor affecting the intensity of poststall gyration?
The airspeed at the time of stall
385
What is the definition of Angle of Attack (AoA)?
The angle between the chordline and the relative wind
386
In a spin, which wing will have the higher AoA up-going or down-going wing?
Down-going (inside) wing
387
What is the cause of autorotation in a spin?
Unequal lift and drag forces acting on each wing
388
What sustains aircraft rolling around the spin axis?
Lift differential between inside and outside wings
389
If stalled and yawed, which aircraft would would enter an inverted spin? (one at +6 G's and one at +3 G's)
Neither. An aircraft must be in a negative G stall and yaw to enter an inverted spin.
390
How does anti-spin rudder aid in recovery?
Slows rotation and decreases AOA
391
Would an aircraft spinning with the stick other than full aft be in an accelerated or unaccelerated spin?
Anytime the aircraft is spinning with the stick other than full aft, the spin is accelerated.
392
Higher pitch attitude at stall results in __________ spin entry and __________ oscillations.
slower; less
393
Will a left or a right spin stabilize at a lower pitch attitude?
Right
394
What causes the variance in left and right spin characteristics?
Gyroscopic effect of the propeller
395
What two conditions must be present in order for an aircraft to spin?
Stall and yaw
396
How does the introduction of yaw affect the lift and drag of a stalled wing?
Causes asymmetrical lift and drag between the outside and inside wing
397
What conditions must be present to enter an inverted spin?
Negative G stall and yaw introduced
398
What is the main aerodynamic factor affecting spins?
Conservation of angular momentum
399
What causes an accelerated spin?
Spinning with the control stick anywhere other than full aft
400
In a right spin, which rudder position will provide the greatest anti-spin forces?
Full left rudder
401
How can a progressive spin be entered?
By maintaining full aft stick while applying and holding anti-spin rudder
402
Which aircraft will enter a spin slower, with less oscillation, and take longer to recover? (4,000 pound vs 6,000 pound)
6,000 pound
403
Which aircraft will spin at a lower pitch attitude and higher rotation rate? (Right spin or left spin)
Right spin
404
How does wake turbulence occur?
Wake turbulence generation occurs anytime the aircraft is producing lift. When the aircraft lands and is no longer producing lift, wake turbulence generation ends
405
Why does an aircraft producing lift create wake turbulance?
T spanwise airflow moves around the wingtip and does more than create induced drag. It also produces spiraling masses of air at the wingtip called wingtip vortices. These wingtip vortices rotate clockwise off the left wing and counterclockwise from the right wing.
406
What is the wake turbulence zone?
The region behind the aircraft containing the trailing vortices is called the wake turbulence zone
407
What determines the strength of wingtip vortices?
Weight, Speed, and Configuration
408
What produces the worst wake turbulence?
Heavy, Clean, and Slow (the things that require the most AoA)
409
Do all aircraft produce wake turbulence?
All aircraft generating lift produce a vortex hazard regardless of their size, speed, or wing configuration
410
What kind of aircraft are most susceptible to wake turbulence?
Short wingspan aircraft
411
What is the best way to prevent a wake turbulence accident?
Avoid the vortices caused by landing and departing aircraft
412
How much time should be given as space behind a heavy aircraft?
2 minutes
413
In addition to the 2-minute spacing rule, what can pilots do to completely avoid the wake turbulence?
Pilots can adjust their liftoff point to before where the aircraft rotated and land beyond their touchdown point
414
What is the minimum landing spacing requirement behind wake turbulence?
3 minutes
415
Does the 2 minute takeoff rule apply to parallel runways?
Yes, because vortices can move laterally near the ground and can create a vortex hazard along other runways
416
What is wind shear?
Sudden change in wind direction and/or speed over a short distance in the atmosphere
417
What is an "increasing performance wind shear?"
As the aircraft crosses the shear line, the stronger headwind will cause higher airspeed and lift.
418
What is a "decreasing performance wind shear?"
As the aircraft crosses the shear line, there will be an abrupt drop in headwind velocity and a corresponding decrease in lift and performance
419
What is a microburst?
The most common type of vertical wind shear
420
What is the maximum airspeed adjustment for wind shear?
10 knots
421
With a reported 15 knot loss, what adjustments will you make?
fly your approach 10 knots faster
422
How do wingtip vortices rotate when looking from behind the aircraft?
Right wing vortex rotates counterclockwise and left wing vortex rotates clockwise.
423
What kind of aircraft will generate the greater wake turbulence?
Heavy, slow, and clean
424
What flaps configuration increases wake turbulence?
Flaps up (high AoA)
425
Which of the following are the factors that primarily affect the strength of vortices?
Weight, speed, and configuration
426
An aircraft flying in which position would experience an induced roll to the left?
Behind the right wingtip
427
This graphic depicts a large aircraft taking off on the center runway with a crosswind from the right of 5 knots.
Which runway(s) do you think will be affected by this aircraft’s wake turbulence?
428
(True/False) Pilots of small aircraft should avoid operating within two rotor diameters of a hovering helicopter due to downwash hazards. However, since a helicopter does not generate wake turbulence, normal spacing rules do not apply.
False
429
Assuming you had to take off behind this departing large aircraft, where would you want to plan your liftoff point?
Before they rotated
430
Assuming you had to take off behind a large aircraft that just landed, where would you want to plan your liftoff point?
After their touchdown point
431
When taking off behind a heavy aircraft (over 255,000 pounds), established spacing requirement is __________ minute(s) minimum. This spacing is also encouraged behind large aircraft (41,000 to 255,000 pounds)
2 minutes
432
If you had to land behind this departing large aircraft (Figure 7-65), where would you want to plan your touchdown point?
Before they rotated
433
If you had to land behind this large aircraft that had just landed on the same runway, where would you want to plan your touchdown point?
After they landed
434
Minimum landing spacing requirement is __________ minute(s) behind a heavy aircraft (over 255,000 pounds)
3 minutes
435
Wind shear is defined as a sudden change in wind __________ over a short distance in the atmosphere.
speed and/or direction
436
Microburst will most likely be encountered in areas of heavy
Rain
437
Key hazards created by wake turbulence are __________ and __________.
induced roll; induced flow field
438
How will a wind shear that decreases your headwind component by 20 knots affect your aircraft?
Indicated airspeed will decrease 20 knots, thereby decreasing lift.
439
During an approach, you pass through a shear that changes the wind from a 10-knot tailwind to a 10-knot headwind. How will this shear affect your aircraft?
Indicated airspeed will increase by 20 knots, lift will increase, and the aircraft will tend to climb above glidepath.
440
An aircraft reported wind shear on final with a 10-knot loss of airspeed. How should you adjust your approach?
Set flaps to “Takeoff” and add 10 knots to your approach speed.
441
What wind changes would an aircraft initially encounter if flown through a microburst?
A strong headwind
