Aerodynamics 1 Flashcards
1
Q
Define Scalar
A
A quantity expressing only magnitude (e.g. Time, amount of money, volume of a body)
2
Q
Define Vector
A
A quantity the expresses both magnitude and direction. A vector quantity is represented by an arrow that displays direction and has a length proportional to magnitude.
3
Q
Define Mass
A
(m) The quantity of molecular material that comprises an object
4
Q
Define Volume
A
The size of the mass, or the amount of space occupied by an object
5
Q
Define Density
A
(ρ) Mass per unit volume
6
Q
Define Force
A
Mass times Acceleration; A vector quantity equal to the push or pull exerted on a body. By Newton’s second law, a force is a function of an acceleration and the mass of the body.
7
Q
Define Weight
A
The force at which a mass is attracted toward the center of the earth by gravity
8
Q
Define Moment
A
A tendency to cause rotation around a point or axis, as a control surface around its hinge or an airplane around its center of gravity; the measure of this tendency, equal to the product of the force and perpendicular distance between the point of rotation and the direction of the force., expressed as a vector. Also called torque.
9
Q
Define Work
A
(W) Work is done when a force acts on a body and it moves. Work is a scalar quantity measured in ft.-lbs. W=F x s
10
Q
Define Power
A
(P) The rate of doing work, or work per unit time. Measured in ft.-lbs./sec or horsepower.
11
Q
Define Energy
A
The ability or capacity to do work. Expressed in ft.-lbs.
12
Q
Define Potential Energy
A
(PE) The ability of a body to do work because of its position or physical state.
13
Q
Define Kinetic Energy
A
(KE) The ability of a body to do work because of its motion.
14
Q
Explain Newton’s Law of Equilibrium
A
Newton’s First Law. “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.”
15
Q
State the requirements for an airplane to be in equilibrium flight
A
Equilibrium flight exists when the sum of all forces and the sum of all moments around the center of gravity are equal to zero. This may occur during straight and level, climbing, or descending flight so long as there is no change in flight path.
16
Q
State the requirements for an airplane to be in trimmed flight
A
Trimmed flight exists when the sum of all moments around the center of gravity is equal to zero. The sum of all forces around the center of gravity may not be equal to zero. This may occur in a constant rate turn.
17
Q
Explain Newton’s Law of Acceleration
A
Newton’s Second Law. “An unbalanced force (F) acting on a body produces an acceleration (a) in the direction of the force that is directly proportional to the force and inversely proportional to the mass (m) of the body.” equation: a=F/m. (e.g. when the airplanes thrust is greater than its drag, the excess thrust will accelerate the airplane until drag increases to equal thrust)
18
Q
Explain Newton’s Law of Interaction
A
Newton’s Third Law. “For every action there is an equal and opposite reaction; the forces of two bodies on each other are always equal and are directed in opposite directions.” (e.g. The rearward force from a propeller’s propwash causes an aircraft to move forward with an equal amount of force)
19
Q
Define Static Pressure
A
(Ps) The weight of a column of air over a given area; the pressure each air particle exerts on another due to the weight of all the particles above; the potential energy per unit volume.
20
Q
Define Air Density
A
(ρ) The total mass of air particles per unit volume
21
Q
Define Temperature
A
A measure of the average kinetic energy of air particles, expressed in degrees (°C), Fahrenheit (°F), or Kelvin (K).
22
Q
Define Lapse Rate
A
The rate that temperature decreases as you increase in altitude. (usually 2 °C per 1000 ft until about 36,000 ft) From about 36,000 ft through 66,000 feet the air remains at a constant -56.5 °C. This is called the isothermal layer.
23
Q
Define Humidity
A
The amount of water vapor in the air
24
Q
Describe the relationship between humidity and air density
A
As humidity increases, density decreases. This is because water molecules have less mass but displace the same number of air molecules.
25
Define Viscosity
(µ) A measure of a fluid's resistance to flow and shearing.
26
Describe the relationship between temperature and viscosity
Air viscosity increases when temperature increases.
27
Define local speed of sound
The rate at which sound waves travel through a particular air mass.
28
Describe the relationship between temperature and local speed of sound
As air temperature increases, the speed of sound increases.
29
State the values for standard atmosphere
* Static Pressure (Ps0) = 29.92 in. Hg. (1013.25 mbar)
* Temperature (T0) = 59 °F (15 °C)
* Average Lapse Rate = 3.57 °F / 1000 ft. (2°C / 1000 ft)
30
Describe the General Gas Law, given static pressure, air density, temperature, and altitude
The standard gas law sets the relationship between the three properties of air: pressure (P), density (ρ), and temperature (T). R is the constant for any given gas. **P=ρRT** (e.g. if density remains constant and temperature increases, then pressure will increase)
31
Explain Bernoulli's Equation, given dynamic pressure, static pressure, and total pressure
Bernoulli's equation explains the variation of pressure exerted by a moving mass of fluid. His equation shows that the total energy of a fluid can be separated into potential energy (static pressure) and kinetic energy (dynamic pressure). **Total pressure (H or Pt) = static pressure (Ps) + dynamic pressure (q).** (Dynamic pressure = 1/2 density (ρ) x velocity (V) squared.)
32
Define Steady Airflow
Airflow in which at every point in the moving air mass, the pressure, density, temperature and velocity are constant.
33
Define Streamline
The path traced by a particle of air while in steady flow
34
Define Streamtube
An impenetrable tube formed by many streamlines. Streamtubes are closed systems.
35
Explain the continuity equation given density, cross-sectional area, and velocity
The amount of mass passing any point in the streamtube may be found by multiplying area by velocity to give volume/unit time and then multiplying by density to give mass/unit time. This is called Mass flow rate (Ṁ) and is expressed as **Ṁ=ρAV**. In subsonic airflow we can ignore changes in density due to compressibility. The mount of mass flowing through any given section of the streamtube must be equal, therefore **if area decreases, velocity increase**. A1V1=A2V2.
36
Define Indicated Altitude
The indication on a pressure altimeter when the Kollsman window is set to the current local altimeter setting.
37
Define Above Ground Level (AGL) altitude
The height of a point measured from the earth's surface directly below it.
38
Define Mean Sea Level (MSL) altitude
The height of a point measured from mean sea level. (Also known as True Altitude)
39
Define Pressure Altitude
**The height above the standard datum plane**. The standard datum plane is the actual elevation at which the barometric pressure is 29.92 in.Hg. (In a standard atmosphere, Pressure altitude equals true altitude)
40
Define Density Altitude
**Pressure altitude corrected for nonstandard temperature.** DA is the pressure altitude on a standard day that has the same density as the ambient air.
41
Describe the pitot-static system given the system components and Bernoulli's equation
Using Bernoulli's equation, dynamic pressure (q), relating to airspeed, can be calculated by measuring the total and static pressure acting on the aircraft. The pitot-static system consists of a **pitot tube that sense total pressure** (H or Pt), and a **static port** that senses static pressure (Ps). H=Ps+1/2ρV^2, By rearranging this equation, we may find velocity.
42
Define Indicated Airspeed
Indicated airspeed is the **actual instrument indication of the dynamic pressure** the airplane is exposed to during flight. This may be significantly different then actual flight speed due to altitude, and installation or instrument error.f
43
Define Calibrated Airspeed
Indicated airspeed corrected for instrument error.
44
Define Equivalent Airspeed
The true airspeed at sea level on a standard day that produces the same dynamic pressure as the actual flight condition. It is found by **correcting calibrated air speed for compressibility error**.
45
Define True Airspeed
**The actual velocity at which an airplane moves through an air mass**. It is found by correcting equivalent airspeed for the difference between the local air density and the density of the air at sea level on a standard day.
46
Define Ground Speed
The airplane's **actual speed over the ground**. If we correct true airspeed for wind, we get ground speed.
47
Describe the factors affecting the different types of airspeed
* **Indicated airspeed** (IAS) is affected by altitude, compressibility effects, instrument error, and installation error.
* **Calibrated airspeed** (CAS) Is affected by altitude and compressibility effects.
* **Equivalent Airspeed** (EAS) is affected by altitude.
* **True Airspeed** (TAS) is the actual speed of the aircraft moving through an air mass.
* **Ground speed** (GS) is affected by wind.
48
Define an aircraft
Any device used or intended to be used for flight in the air.
49
Define an airplane
An engine driven, heavier-than-air, fixed wing aircraft that is supported by the dynamic reaction of airflow over its wings.
50
Describe the five components of an airplane
* **Fuselage:** basic structure of the airplane to which all other components are attached
* **Wing:** an airfoil attached to the fuselage designed to produce lift
* **Empennage:** the assembly of the stabilizing and control surfaces on the tail of the airplane
* **Landing Gear:** permits ground taxi operations and absorbs the shock encountered during takeoff and landing
* **Engine:** provides thrust necessary for powered flight
51
State the advantages of the semi-monocoque fuselage construction
**The semi-monocoque fuselage is lightweight and is easier to repair than a monocoque fuselage.** The T-6B uses a semi-monocoque fuselage
52
Define full cantilever wing construction
**All bracing is internal to the wing.** T-6B wings are full cantilever.
53
Describe the airplane three-axis reference system
* **longitudinal axis:** passes from nose to tail;
* movement about this axis is called **roll**.
* control surface: **Ailerons**
* **lateral axis:** passes from wingtip to wingtip;
* movement about this axis is called **pitch**.
* control surface: **Elevator**
* **vertical axis:** passes vertically through the center of gravity;
* movement about this axis is called **yaw**.
* control surface: **Rudder**
54
Define chord line
An infinitely long straight line that passes through the leading and trailing edges.
55
Define chord
The precise measurement between the leading and trailing edges along the chord line.
56
Define root chord
The chord measured at the wing centerline.
57
Define tip chord
The chord measured at the wingtip.
58
Define average chord
The average of every chord from the wing root to the wing tip.
59
Define mean camber line
The locus of points halfway between the upper and lower surfaces, measured perpendicular to the mean chamber line itself.
60
Define symmetric airfoil
An airfoil in which the mean camber line is coincident with the chord line. Also called a zero camber airfoil.
61
Define positive chamber
An airfoil in which the mean camber line is above the chord line
62
Define negative camber
An airfoil in which the mean camber line is below the chord line.
63
Define spanwise flow
**Airflow that travels the span of the wing,** parallel to the leading edge, normally root to tip. This airflow is not accelerated over the wing and therefore produces no pressure differential or lift.
64
Define chordwise flow
Airflow perpendicular to the leading edge of an airfoil; **airflow along the chord of an airfoil**. Since chordwise flow is accelerated over a wing, it **produces lift**.
65
Define pitch attitude
(θ) The angle between the longitudinal axis of the airplane and the horizon.
66
Define flight path
(FP) The path described by an airplanes center of gravity as it moves through an air mass.
67
Define relative wind
(RW) **The airflow experienced by the aircraft as it flies through the air**. It is always equal and opposite to the flightpath. The relative wind may arise from the motion of the body, from the motion of the air, or from both.
68
Define angle of attack
(AOA, α) The angle formed between the relative wind and the chord line of the airfoil.
69
Define angle of incidence
**The angle between the airplane's longitudinal axis and the chord line of its wing**. The root chord is commonly chosen to measure the angle of incidence.
70
Define Dihedral angle
**The angle between the spanwise inclination of a wing and the lateral axis**. It is the upward slope of the wing when viewed from head on. A negative dihedral is called anhedral.
71
Define Wingspan
(b) The length of a wing, measured from wingtip to wingtip. Also called span. **The wingspan of the T-6B is 33'5"**
72
Define Wing area
(S) **The surface area of a wing from wingtip to wingtip**. The area within the outline of a projection of a wing on the plane of its chord, including that area lying within the fuselage or nacelles. With a swept wing, the area within the fuselage is contained within lines having the same sweep angles as the leading and trailing edges, fairings or fillets being ignored.
73
Define wing loading
(WL) A ratio of airplane weight to the wing surface area.
74
Define taper ratio
(λ) **The ratio of tip chord to root chord**. The ratio affects the lift distribution and the structural weight of the wing. **The T-6B tapered wings.**
75
Define Sweep angle
(Λ) **The angle between the lateral axis and a line drawn 25% aft of the leading edge.** Also called sweepback. **The T-6B wing is swept.**
76
Define aspect ratio
(AR) The ratio of the wingspan to the average chord.
77
Define the center of gravity
(CG) The point at which the weight of an object is considered to be concentrated and about which all forces and moments are measured.
78
Define the aerodynamic center
(AC) **The point along the chord line of an airfoil where all changes in aerodynamic force effectively take place**. It is normally located at the point of 25% chord.
79
Describe the motions that occur around the airplane center of gravity
The movement of the airplane can be described by the movement of its center of gravity. Relative movement around all three axes occurs around the CG.
80
Explain the aerodynamic relationship of the four primary forces of equilibrium flight
* **Weight** is the force of the earths gravity acting on the aircraft and is always pointed toward the center of the earth.
* **Thrust** is produced by the jet engine or propeller.
* **Lift** primarily acts against weight.
* **Drag** primarily acts against thrust and retards aircraft motion
81
State the pressure distribution around an airfoil , given changes in angle of attack and camber
At zero AOA, a positively cambered airfoil will have lower pressure on the upper surface, thus generating lift. As AOA increases, lift will increase. A symmetric airfoil will have equal pressure distribution on upper and lower surface, thus generating no lift at zero AOA. Positive AOA will generate lift.
82
Define the lift component of aerodynamic force
The component of the aerodynamic force acting perpendicular to the relative wind
83
Describe how factors in the lift equation affect lift production, given density, velocity, surface area, and coefficient of lift.
* An increase in **density** will increase lift.
* An increase in **velocity** will increase lift.
* An increase in **surface area** will increase lift.
* A larger **coefficient of lift** will increase lift.
* Compressibility, aspect ratio, viscosity, angle of attack, and camber are all accounted for in the coefficient of lift.
84
List the factors affecting the coefficient of lift that the pilot can directly control.
The shape of the airfoil and the angle of attack
85
Define the drag component of aerodynamic force.
The component of the aerodynamic force acting parallel to, and in the same direction as the relative wind.
86
Define parasite drag and its components: form, friction, and interference drag
* (Ps) **Parasite drag** is all drag not associated with the production of lift.
* **Form drag** is drag resulting from airflow over a surface with some frontal area, often referred to as pressure drag, profile drag, or plate drag.
* **Friction** drag is drag arising from friction forces at the surface of an aircraft due to viscosity of the air.
* **Interference drag** is drag caused by the mixing of streamlines around aircraft components due to their proximity.
87
Describe the measures that can be take to reduce each of the components of parasite drag.
* To reduce **form drag**, the fuselage and other surfaces exposed to the airstream are streamlined (shaped like a teardrop).
* **Friction drag** can be reduced by smoothing the surfaces of the airplane through painting, cleaning, waxing, polishing, or using flush rivets.
* Proper fairing and filleting will reduce **interference drag**.
88
State the effects of up wash and down wash on an **infinite wing**
Up was increases lift and down wash decreases lift proportionally. Therefore there is **no net change in lift**.
89
State the effects of up wash and down wash on a **finite wing**.
Some of the high pressure air in the leading edge stagnation point flows spanwise to the wingtips and up to the upper surface of the wing. It combines with the other down wash when it flows over the trailing edge, therefore **reducing effective lift** and **increasing induced drag**.
90
Define induced drag
That portion of total drag resulting from the production of lift.
91
State the cause of induced drag on a finite wing
Since there is twice as much down wash as up wash near the wingtips of a finite wing, the average relative wind is slanted downward, thus the total lift vector will be inclined aft. The horizontal component of total lift is induced drag.
92
Describe factors affecting induced drag, given the induced drag equation, and changes in lift, weight, density velocity, and wingspan
Increasing lift or weight will increase induced drag. Increasing density (ρ), velocity (V), or wingspan (b) will reduce induced drag.
93
State when a plane will enter ground effect.
Within one wingspan of the ground. (About 33 ft for the T-6B)
94
State the effects of ground effect on lift, effective lift, and induced drag
The decrease in downwash allows the total lift vector to rotate forward, **increasing effective lift and decreasing induced drag**.
95
Describe effects of angle of attack changes on coefficient of lift and coefficient of drag.
As AOA increases, lift increases up to a maximum value (Clmax). The coefficient of drag is low and nearly constant at low AOA, but increases rapidly at higher angles of attack.
96
Explain the lift to drag ratio, using the lift and drag equations.
A high L/D ratio indicates a more efficient airfoil. It is calculated by dividing lift by drag.
97
Explain the importance of L/D MAX.
* L/DMAX AOA produces the minimum total drag;
* the airfoil produces an equal amount of parasite drag and induced drag;
* it produces the greatest ratio of lift to drag;
* and it is the **most efficient angle of attack**.
98
Define total drag.
Parasite drag and Induced drag added together.
99
Describe the effects of changes in velocity on total drag
Total drag will be lowest where induced drag and parasite drag are equal. It will increase rapidly at lower airspeed and increase gradually at higher airspeeds.
100
Define thrust components: thrust required and thrust available.
* **Thrust Required** (Tr) is the thrust required to overcome drag to maintain level equilibrium flight.
* **Thrust available** (Ta) is the thrust an engine produces under a specific velocity, density, and throttle setting.
101
Define power components: power required and power available
* **Power required** (Pr) is the power required to produce enough thrust to overcome drag in equilibrium flight.
* **Power available** (Pa) is the power an engine is producing.
102
Describe the effects of throttle setting on thrust available.
* Full throttle will result in greatest thrust available.
* As throttle is retarded, thrust available decreases.
103
Describe the effects of velocity on thrust available.
* For turbo-prop aircraft, thrust available decreases with an increase in velocity.
* For turbojets, thrust available remains the same regardless of velocity.
104
Describe the effects of density on thrust available.
As air density decreases thrust available decreases.
105
Describe the effects of throttle setting on power available.
* Full throttle will result in greatest power available.
* As throttle is retarded, power available decreases.
106
Describe the effects of velocity on power available.
* For turbo-prop aircraft, As velocity increases, power available will initially increase, but will then decrease due to a decrease in thrust available.
* For turbojets, power available will increase linearly
107
Describe the effects of density on power available.
As air density decreases power available decreases.
108
Define thrust horsepower and components: shaft horsepower and propeller efficiency
* **Thrust horsepower** (THP) is the actual amount of horsepower that an engine-propeller system transforms into thrust, equal to shaft horsepower multiplied by propeller efficiency.
* **Shaft horsepower** (SHP) is the horsepower delivered at the rotating driveshaft of an engine.
* **Propeller efficiency** (PE) is a measure of the effectiveness of a propeller in converting shaft horsepower into thrust horsepower.
109
State the maximum rated shaft horsepower in the T-6B
1100 SHP
110
Explain how propeller efficiency affects thrust horsepower
Under ideal conditions thrust horsepower would equal shaft horsepower, but propeller efficiency is never 100%, and the lower its efficiency, the less thrust horsepower is produced.
111
Describe power required in terms of thrust required
Power required is the amount of power required to produce thrust required.
112
State the location of L/D MAX on the thrust required curve.
L/D Max is at the bottom of the thrust required curve.
113
State the location of L/DMAX on the power required curve.
L/DMAX is to the right of the bottom of the power required curve (where a line drawn from the origin is tangent to the Pr curve)
114
Describe how thrust required and power required vary with velocity
Thrust required is lowest at L/D max, increases rapidly at lower velocities, and increases gradually at higher velocities. Power required follows a similar pattern, but curves back up at a lower velocity than L/D max.
115
Define excess thrust and excess power
* Excess thrust occurs when thrust available is greater than thrust required. Te=Ta-Tr.
* Excess power is similar to excess thrust, and occurs when power available is greater than power required. Pe=Pa-Pr
116
Describe the effects of excess thrust and excess power
Excess thrust and excess power will produce a climb, acceleration, or both.
117
Describe the effects of changes in weight on thrust and power components: thrust required, power required, excess thrust, and excess power
* An increase in weight will require an increase in thrust required and a corresponding increase in power required.
* Weight changes have no effect on thrust available and power available,
* thus thrust excess and power excess will decrease.
118
Describe the effects of changes in altitude on thrust and power components: thrust required, power required, thrust available, power available, excess thrust, and excess power
* As altitude increase, the thrust required curve shifts to the right, but not up.
* Since power required is a function of thrust required and velocity, the Pr curve will shift up and to the right.
* Both thrust available and power available will decrease as altitude increases.
* Thrust excess and Power excess will also decrease with an increase in altitude.
119
Describe the effects of changes in configuration on thrust and power components: thrust required, power required, excess thrust, and excess power
* Lowering the landing gear will increase drag, thus causing thrust required and power required to increase.
* Lowering the flaps increases the coefficient of lift, but also greatly increase parasite drag, thus the thrust required and power required curves shift up and to the left.
* Configuration changes have no effect on Thrust available and Power available, therefore if landing gear or flaps are lowered, excess thrust and excess power will decrease.
120
Describe the aerodynamic effects of raising or lowering the flaps
Lowering the flaps increases the coefficient of lift, allowing the aircraft to fly at lower velocity, but also significantly increases drag.
121
Describe the aerodynamic effects of raising and lowering the landing gear
Lowering the landing gear has no effect on lift, but does dramatically increase parasite drag.
122
Explain the aerodynamic effects of the elevator.
If stick is pushed forward, the elevator moves down, increases the camber of the tail, producing lift, raising the tail, and pitching the nose down.
123
Explain the aerodynamic effects of the ailerons.
If the stick is pushed left, the left aileron raises creating negative camber on the left wing, producing lift in the downward direction. At the same time, the right aileron lowers increasing the camber on the right wing, producing more lift. This difference in lift causes the airplane to roll left.
124
Explain the aerodynamic effects of the rudder.
Stepping on the left rudder pedal will cause the rudder to deflect left, creating lift on the right side of the tail and yawing the airplanes nose to the left.
125
Describe how the trim tab system holds an airplane in trimmed flight
A trim tab at the trailing edge of a control surface creates a force that moves the control surface opposite the direction the tab is oriented. For example a trim tab on the elevator that is deflected down, will create a force that will cause the elevator to deflect up. The total force from the elevator will cause the airplane to pitch nose up. The pilot trims to relieve pressure on the controls so that they stay in the desired position without being held there by the pilot.
126
Define aerodynamic balancing
**The feature of a control surface that reduces the magnitude of the aerodynamic moment around the hinge line.** Keep control pressures associated with higher velocities within reasonable limits.
127
Define Mass Balancing
The feature of a control surface that reduces the magnitude of the inertial and gravitational moments around the hinge line.
128
State the methods for aerodynamic and mass balancing employed on the T-6B
* Aerodynamic balancing is accomplished on the T-6B through the use of shielded horns on the elevator and rudder.
* For mass balancing, weights are placed inside the control surface overhang, ahead of the hinge line.
129
What are the three basic types of control systems?
Conventional, power boosted, and full-power
130
State the characteristics of conventional controls
The forces applied to the stick and rudder pedals are directly transferred to the control surfaces via push-pull tubes, pulleys, cables, and levers. This system gives the pilot direct feedback on control pressures.
131
State the characteristics of power-boosted controls.
Power-boosted controls use hydraulic, pneumatic, or electric boosters to assist the pilot in moving the controls. If the boost system fails, the pilot can still control the airplane, but control forces will be greatly increased.
132
State the characteristics of full-power controls
With full-power or fly-by-wire controls, the pilot has no direct connection with the control surfaces. The surfaces are controlled by hydraulic valves or electrical switches, which are directed by computer commands. This system requires artificial feel since there is no feedback from the control surfaces.
133
State how trim tabs can be used to generate artificial feel on a control surface
* Servo tabs move in the opposite direction of the surface, making it easier for the pilot to deflect the control surface.
* Anti-servo tabs move in the same direction, requiring more force to deflect the control surface.
134
Describe the purpose of bobweights and downsprings
The bobweight increases the force required to pull the stick aft during maneuvering flight, while the downsprings increase the force required to pull the stick aft at low airspeeds.
135
DEFINE the boundary layer
The boundary layer is the layer of airflow over the surface that demonstrates local airflow retardation due to viscosity.
About 1mm thick.
136
3.2 DESCRIBE the different types of flow within the boundary layer
**Laminar flow:** moves smoothly along in streamlines.
Easily separated from surface.
**Turbulent flow**: streamlines break up and flow irregularly and disorganized.
Adheres to surface well.
137
3.4 DEFINE CL MAX AOA
CL MAX AOA is the stalling AOA or critical AOA.
Any increase in AOA beyond CL MAX AOA will result in a decrease in CL.
138
3.5 DEFINE stall, in a classroom
A stall is a condition in flight where an increase in AOA results in a decrease in CL.
139
3.6 EXPLAIN how a stall occurs
A stall occurs when the boundary layer separation point progresses toward the leading edge of the airfoil until it stalls. The airflow cannot turn that sharply around the leading edge.
140
IDENTIFY the aerodynamic parameters causing a stall, in a classroom, in accordance with Naval Aviation Fundamentals,
Excessive AOA beyond CL MAX.
Speed or any other flight conditions have no effect.
141
3.8 COMPARE power-on and power-off stalls, in a classroom, in accordance with Naval Aviation Fundamentals,
**Power off**: VS is the minimum true airspeed required to maintain level flight at CL MAX AOA.
**Power on**: Less than power off speed because at high pitch attitudes, part of the weight of the airplane is being supported by the vertical component of the thrust.
VS = 2(W-Tsinθ)ρSCLMAX
142
3.9 DESCRIBE the order of losing control effectiveness approaching a stall in the T-6B, in a classroom, in accordance with Naval Aviation Fundamentals,
Loss of control effectiveness progresses from ailerons to elevator to rudder.
143
3.10 EXPLAIN the difference between true and indicated stall speed, in a classroom, in accordance with Naval Aviation Fundamentals,
IAS does not change with altitude. TAS stall speed increases with altitude.
144
3.11 EXPLAIN the effects of gross weight, altitude, load factor and maneuvering on stall speed, given the stall speed equation, in a classroom, in accordance with Naval Aviation Fundamentals,
As weight decreases, stall speed decreases.
As altitude increases, stall speed increases.
Power on stall speeds are less than power off.
145
3.14 DESCRIBE devices used to control boundary layer separation, in a classroom, in accordance with Naval Aviation Fundamentals,
* **Slots** that redirect high pressure air from below the wing into the boundary layer, allowing it to overcome the adverse pressure gradient.
* **Slats** are just moveable slots.
Neither of these change CL at low AOA.
* **Vortex generators** are small vanes placed on the leading edge to disrupt the laminar flow into turbulent flow.
146
3.15 DESCRIBE devices used to change the camber of an airfoil, in a classroom, in accordance with Naval Aviation Fundamentals,
Trailing edge: Plain flap, split flap, fowler flap, and slotted flap.
Leading Edge: Plan flap and slotted flap.
147
3.16 DESCRIBE methods of stall warning used in the T-6B, in a classroom, in accordance with Naval Aviation Fundamentals,
Stall at 18 units of AOA.
Utilizes AOA indexer and stick shaker.
148
3.18 DESCRIBE the various methods of wing tailoring, including geometric twist, aerodynamic twist, stall strips, and stall fences,
* **Geometric twist**: decrease in angle o incidence from wing root to tip. Decreased AOA at wingtip so the root stalls first.
* **Aerodynamic twist**: Gradual change in airfoil shape that increases CL MAX AOA to a higher value near the tip.
* **Stall fence**: redirect the airflow long the chord, thereby delaying tip stall.
* **Stall strip**: Small metal piece attached to leading edge to induce a stall at the root, before the tip.
