AERT 4040 Flashcards

Aerodynamics

1
Q

Density Altitude is used as a predictor of aircraft performance, not as a height reference.
True
False

A

True

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2
Q

An aircraft’s Mach Number is the aircraft’s

Local Speed of Sound divided by TAS

IAS divided by the Local Speed of Sound

TAS divided by the Local Speed of Sound

A

TAS divided by the Local Speed of Sound

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3
Q

The temperature and pressure conditions for a standard day are ______________.

59 degrees F / 15 degrees C and 29.92 in of Hg / 1013 mbar

There is no such thing as a standard day

68 degrees F / 20 degrees C and 30.30 in of Hg / 1026 mbar

A

59 degrees F / 15 degrees C and 29.92 in of Hg / 1013 mbar

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4
Q

What did the Wright brothers think was the most difficult problem, thus the first problem they attacked when building their Flyer?

Design of the wings

How to control and balance the aircraft

Developing a means of propulsion

A

How to control and balance the aircraft

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5
Q

Density is

is always expressed by Liters per Pound

Mass per unit volume

Weight per unit volume

A

Mass per unit volume

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6
Q

The Critical Mach Number of an aircraft is the highest Mach Number the aircraft can travel before structural damage is done to the airframe.
True
False

A

False

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7
Q

How did the Wrights correct their problem of roll reversal?

They used a canard rather than an elevator

They used counter-rotations propellers

They developed a movable rudder and connected it to the roll control

A

They developed a movable rudder and connected it to the roll control

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8
Q

What method did the Wright brothers use to control roll?

The used what was later called flight spoilers

They developed a technique of wing warping

They developed ailerons

A

They developed a technique of wing warping

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9
Q

The speed of sound in air is dependent upon the

Air Density only

A combination of Air Temperature, Air Density and Humidity

Air Temperature only

A

Air Temperature only

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10
Q

What was unique about the engine that the Wrights used for their Flyer?

It was the first time aluminum was used in the construction od an aircraft

It was the first use of 100 LL fuel

It was the first use of a six cylinder engine

A

It was the first time aluminum was used in the construction od an aircraft

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11
Q

Air viscosity __________ as the air temperature increases.

Increases

Stays the same

Decreases

A

increases

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12
Q

Total pressure is:

measured parallel to the local stream

1/2ρV²

static pressure minus dynamic pressure

static pressure plus dynamic pressure

A

static pressure plus dynamic pressure

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13
Q

The General Gas Law sets the relationship between three properties of air: pressure (P), density (ρ), and temperature (T). It is expressed as an equation where R is a constant for any given gas. What is the correct expression of the General Gas Law.

ρT = PR

ρP = RT

ρ = P/RT

ρPT =

A

ρ = P/RT

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14
Q

The Law of Interaction states __________.

“Two opposite forces cannot interact.”

“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.”

“A body at rest tends to stay at rest.”

“For every action there is an equal and opposite reaction.”

A

“For every action there is an equal and opposite reaction.”

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15
Q

The angle of incidence of a wing is the angle between a line drawn through the 25% cord points and a line drawn parallel to the lateral axis.
True
Fasle

A

False

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16
Q

Static pressure acts:

in the direction of the flow

perpendicular to the surface that any air molecules collide with.

perpendicular to the direction of flow

in the direction of the total pressure

A

perpendicular to the surface that any air molecules collide with.

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17
Q

A moment is _________.

created when a force is applied at some distance from an axis or fulcrum, producing rotation about that point

the result of mass x acceleration

a body’s capacity to do work

the force with which a mass is attracted toward the center of the earth

A

created when a force is applied at some distance from an axis or fulcrum, producing rotation about that point

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18
Q

The center of gravity is the point at which __________.

lift is generated

all weight is concentrated

all aerodynamic forces are concentrated

elevator authority is lost

A

all weight is concentrated

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19
Q

Wing Loading is:

the aircraft weight divided by the sine of the wing dihedral

the ratio of the aircraft weight to the surface area of the wing

the ratio of the aircraft weight to the wing span

the ratio of the aircraft weight to the volume of the wing

A

the ratio of the aircraft weight to the surface area of the wing

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20
Q

The Mean Camber Line:

is a line drawn halfway between the wing root and the wing tip/

is the line drawn perpendicular to the aerodynamic center of the wing

is a line drawn halfway between the leading edge and trailing edge of the wing

is a line drawn halfway between the upper and lower surface of an airfoil.

A

is a line drawn halfway between the upper and lower surface of an airfoil.

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21
Q

The chord of an airfoil is defined as ___________.

an infinitely long line drawn through the leading and trailing edges of an airfoil

a measure of the wing along the chord line, from the leading edge to the trailing edge

the angle between the longitudinal axis and the horizon

the length of a wing

A

a measure of the wing along the chord line, from the leading edge to the trailing edge

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22
Q

Which formula or equation describes the relationship between force (F), acceleration (a) and mass (m)?

F = ma

a = Fm

m = Fa

F = m/a

A

F = ma

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23
Q

The angle of attack of a wing is the angle between the wing’s cord and the horizon
True
False

A

False

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24
Q

The axis is which the aircraft nose moves left or right about the center of gravity
pitch
yaw
center
roll

A

yaw

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25
The camber of an airfoil: is the average distance between the cord and the mean camber line measured perpendicular to the cord is expressed as a percentage of the wing surface area. is the maximum distance between the cord and the mean camber line measured perpendicular to the cord is the distance between the cord and the mean camber line measured at the aerodynamic center of the wind
is the maximum distance between the cord and the mean camber line measured perpendicular to the cord
26
Aspect Ratio of a wing is the ratio of the wingspan to the average cord the ratio of the average cord to the camber the ratio of the wing surface area to the average cord the ratio of the wing surface area to the wingspan
the ratio of the wingspan to the average cord
27
A _________ airfoil produces lift at zero degrees angle of attack. symmetric tapered dihedral positively cambered
positively cambered
28
What does sweeping a wing back do to CLMAX Slightly decreases CLMAX and increases Stall AOA Slightly increases CLMAX and increases Stall AOA Slightly decreases CLMAX and decreases Stall AOA Slightly increases CLMAX and decreases Stall AOA
Slightly decreases CLMAX and increases Stall AOA
29
Aspects of which two laws seem to contribute to the production of lift? Ohm's Law and the Heisenberg Uncertainty Principle Bernoulli's Law and Newton's Third Law of Motion Pascal's Law and Bernoulli's Law General Gas Law and Newton's Second Law of Motion
Bernoulli's Law and Newton's Third Law of Motion
30
Velocity and AOA are ____________ related in level flight Directly Not at all Inversely
inversely
31
The AOA which produces CLMAX is called the: Best rate of climb AOA Stall AOA Best Angle of Glide AOA Best Angle of Climb AOA
Stall AOA
32
As the AOA increases, the center of lift ___________. Moves rearward Moves forward Stays Stationary
moves forward
33
When an aircraft flies more slowly, more AOA is needed, when it flies faster less AOA is needed true false
true
34
L/DMAX is the point where . drag is the greatest the ratio of lift to drag is the greatest the stall angle of attack is reached lift is the greatest
the ratio of lift to drag is the greatest
35
Which factors are accounted by the Coefficient of Lift? Velocity Angle of Attack Aspect Ratio Camber Surface area of the wing Viscosity Air Density Compressibility
AOA Velocity Camber Compressibility Aspect Ratio
36
AOA is the most important factor in the CL and the easiest for the pilot to change true false
true
37
The Center of Pressure is the point on the wing where the vectors of lift and drag act true false
true
38
What are the factors that affect lift? Compressibility Air Density Viscosity Dihedral Angle Mean Cord Length Aspect Ratio Angle of Attack Surface area of the wings Velocity Camber
Compressibility air density viscosity aspect ration angle of attack surface area of the wings velocity camber
39
Ground Effect __________. Drastically increases lift available Reduces the interference drag of the landing gear Reduces the low pressure wake which causes form drag Blocks the effect of Induced Drag
Blocks the effect of Induced Drag
40
When does ground effect start becoming a factor? 50 feet AGL one wingspan above the ground two wingspans above the ground 100 feet AGL
one wingspan above the ground
41
Drag that is produced simply due to the production of lift is called ________. Interference Drag Form Drag Induced Drag Viscous Drag
induced drag
42
Parasite drag is ___________. the component of drag associated with the production of lift minimized by installing winglets, wingtip fuel tanks or missile rails greatest at low airspeeds made up of form, friction, and interference drag
made up of form, friction, and interference drag
43
Streamlining shapes and increasing _________ are useful methods of reducing form drag. Angle of Attack Viscous Drag Velocity Frontal Area
Viscous Drag
44
Total drag is composed of ____________. upwash and downwash form and interference drag parasite and induced drag thrust and lift
parasite and induced drag
45
Which of these are true about L/D Max - Any movement away from L/D Max airspeed will increase total drag - L/D Max AOA produces minimum total drag - L/D Max AOA corresponds to the aircraft's maximum speed - At L/D Max, induced and parasite drag are equal to each other. - The maximum amount of lift that an aircraft can produce occurs at L/D Max AOA
Any movement away from L/D Max airspeed will increase total drag L/D Max AOA produces minimum total drag At L/D Max, induced and parasite drag are equal to each other.
46
Drag that is created by airflow separating from the surface of an object and the low pressure wake that is created by that separation is called __________. Interference Drag Form Drag Viscous Drag Induced Drag
form drag
47
Drag that is created by mixing airstreams between components is called _________. Form Drag Interference Drag Viscous Drag Induced Drag
Interference Drag
48
An increase in weight or altitude will ____________ L/D Max airspeed but will ___________ L/D Max AOA. decrease / not affect decrease / increase increase / not affect increase / decrease
increase / not affect
49
Accelerating the air that surrounds a moving object requires force, thus creating drag. This is an example of _________ drag. Form Drag Interference Drag Induced Drag Viscous Drag
Viscous Drag
50
In a jet aircraft, as velocity increases, thrust available _________. Decreases Stays the same Increases
stays the same
51
With a variable pitch prop, what instrument in the cockpit is used to represent power? Prop Pitch Engine Exhaust Temperature Shaft Torque PRM
shaft torque
52
An increase in aircraft weight will shift the thrust required and power required curves down and to the right up and to the left down and to the left up and to the right
up and to the right
53
A thrust required curved can be use for various, weights, altitudes and configurations. true false
false
54
Lowering an aircraft's landing gear will shift the thrust required and power required curves up and to the right straight up up and to the left straight down
straight up
55
What are the five basic types of jet engines? Centrifugal Flow Engine Water Injected Engine Ramjet Engine Rocket Assisted Engine Radial Flow Engine Turbofan Engine Circular Flow Engine Axial-Centrifugal Compressor Engine
- Axial-Centrifugal Compressor Engine - Centrifugal Flow Engine - Turbofan Engine - Radial Flow Engine - Ramjet Engine
56
In equilibrium flight, thrust must ____________ drag. be less than be equal to be greater than
be equal to
57
Torque and P-Factor both affect how propeller aircraft fly. What effect to each have on aircraft The both create a yawing motion Torque creates a rolling motion, P-Factor creates a yawing motion. They both create a rolling motion Torque creates a yawing motion, P-Factor creates a rolling motion
Torque creates a rolling motion, p-factor creates a yawing motion
58
For a propeller driven aircraft, max excess power occurs at L/D Max airspeed A speed less than L/D Max A speed greater than L/D max
L/D max airspeed
59
For a jet, power available increases linearly with an increase of velocity. true false
true
60
Since aircraft designers wish to minimize the effects of P-Factor, they align the thrust axis with the relative wind for cruise airspeeds. Thus, P-Factor will be most prevalent at AOAs significantly different from cruise AOA. true false
true
61
How do you locate L/D Max for a propeller driven aircraft on a Power Required (Power vs. Velocity) Curve Draw a straight line starting at the origin of the graph and tangent to the curve. The tangent point is L/D Max. L/D Max occurs where the slope of the graph is equal to one L/D Max occurs five knots slower than the lowest point on the graph L/D Max is the lowest point on the graph
Draw a straight line starting at the origin of the graph and tangent to the curve. The tangent point is L/D Max.
62
For a propeller driven aircraft, max excess thrust occurs at L/D Max Airspeed A speed greater than L/D Max a speed less than L/D Max
a speed less than L/D Max
63
Output from an engine in a propeller driven aircraft is called Shaft Horsepower Centrifugal Horsepower Brake Horsepower Thrust Horsepower
Shaft Horsepower
64
Slipstream swirl is the most noticeable at high power settings at high airspeed low power settings at low airspeed high power settings at low airspeed low power settings at high airspeed
high power settings at low airspeed
65
Maximum power available occurs at the full throttle setting. true fasle
true
66
For both jet and propeller driven aircraft, as air density decreases, thrust ________. Increases Stays the same Decreases
Decresases
67
Output from a propeller is called Shaft Horsepower Brake Horsepower Thrust Horsepower Centrifugal Horsepower
Thrust Horsepower
68
Propeller Efficiency is determined by Thrust Horsepower divided by Shaft Horsepower true false
true
69
For a turbojet, max excess thrust occurs at _________________. At a speed less than L/D Max At a speed greater than L/D Max L/D Max Airspeed
L/D Max Airspeed
70
In a propeller driven airplane, as velocity increases, thrust available ______. Decreases Stays the same Increases
decreases
71
For a turbojet aircraft, max excess power occurs at L/D Max airspeed A speed greater than L/D Max A speed less than L/D Max
A speed greater than L/D Max
72
Power on stall speed will be _______________ power off stall speed faster than the same as lower than
lower than
73
The only reason an aircraft stalls is because The only reason an aircraft stalls is because the wings have exceeded the stalling pitch angle the aircraft has slowed below Vstall Thrust required exceeds thrust available the wings have exceeded the stalling angle of attack
the wings have exceeded the stalling angle of attack
74
What is the only thing that needs to be done to recover from a stall? What is the only thing that needs to be done to recover from a stall? Increase thrust available to over thrust required Lower the aircraft's nose below the horizon Decrease the AOA below the stalling angle of attack Increase the aircraft's speed to greater than Vstall
Decrease the AOA below the stalling angle of attack
75
The slotted flap is more advantageous than a plain flap because air passing through the slot aids in boundary layer control true false
true
76
Different things can be done to the design to a wing to give it good stall characteristics. The most common of these techniques are Different things can be done to the design to a wing to give it good stall characteristics. The most common of these techniques are Geometric wing twist Installation of a stall strip Installation of vortex generators Installation of a wing fence Aerodynamic wing twist
Aerodynamic wing twist Geometric wing twist Installation of a stall strip
77
The most desirable stall pattern of a wing is one where the wing starts to stall at the wingtip and moves inboard. true false
false
78
Most slats increase lift by increasing the wing's camber true false
false
79
Swept wings are used on high speed aircraft because they reduce drag and allow the aircraft to fly at higher mach numbers. Swept wings stall at the root first and progresses rapidly outward across the rest of the wing. true false
false
80
When flaps are lowered, the pilot should raise the nose due to the increase drag of the flaps lower the nose due to the increased drag of the flaps attempt to keep his flight attitude the same lower the nose to keep the increase of lift from ballooning the aircraft
lower the nose to keep the increase of lift from ballooning the aircraft
81
Fowler flaps are very effective high lift devices because they increase the camber of the wing They increase the aspect ratio of the wing The have several slots so they aid in boundary layer control since they move aft, they also increase the surface area of the wing
The have several slots so they aid in boundary layer control since they move aft, they also increase the surface area of the wing they increase the camber of the wing
82
As a stall progresses, the _________ lose control effectiveness first, followed by the ________ and then finally the _________. ailerons, rudder, elevators rudder, ailerons, elevators elevator, ailerons, rudder ailerons, elevators, rudder
ailerons, elevators, rudder
83
The two common types of high lift devices Increase camber Delay boundary layer separation Increase the angle of attack Increase the aspect ratio
Increase camber Delay boundary layer separation
84
Rectangular wings are limited to low speed, light weight construction where simplicity of construction and good stall characteristics are the predominant requirements true false
true
85
Erect spins are either unaccelerated or accelerated. What control input will make a spin unaccelerated? Rudder in the direction of spin Full forward stick/yolk Full aft stick/yolk Ailerons against the direction of spin
Full aft stick/yolk
86
How can you tell the difference between a spin and a spiral? Airspeed Roll rate Rate of descent Pitch attitude
Airspeed
87
It is impossible for an aircraft to enter an inverted spin True False
False
88
What two things do you need for a spin The aircraft's CG must be in the aft half of the flight envelope The elevator must be trimmed nose down A stalled aircraft Some sort of yawing force must be present
A stalled aircraft Some sort of yawing force must be present
89
A spin is an aggravated stall that results in autorotation True False
True
90
Slow activation of the elevators during the spin allows the spin to accelerate. This makes for a much easier and smoother recovery true false
false
91
What keeps the spin goin? The P-Factor from the engine Due to the yawing motion, the wings are not symmetrically stalled. Gyroscopic precession caused by the engine or prop Any difference in wing fuel quantity
Due to the yawing motion, the wings are not symmetrically stalled.
92
Poststall gyrations are dependent upon an aircraft's _________. weight airspeed CG G loa
airspeed
93
An aircraft's spin axis is always located in the center of the fuselage at the 50% cord line. true false
false
94
What is usually the most effective control for stopping the autorotation Rudder Elevators Aileron
Rudder
95