AERT 4040 Flashcards
Aerodynamics
Density Altitude is used as a predictor of aircraft performance, not as a height reference.
True
False
True
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
TAS divided by the Local Speed of Sound
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
59 degrees F / 15 degrees C and 29.92 in of Hg / 1013 mbar
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
How to control and balance the aircraft
Density is
is always expressed by Liters per Pound
Mass per unit volume
Weight per unit volume
Mass per unit volume
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
False
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
They developed a movable rudder and connected it to the roll control
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
They developed a technique of wing warping
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
Air Temperature only
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
It was the first time aluminum was used in the construction od an aircraft
Air viscosity __________ as the air temperature increases.
Increases
Stays the same
Decreases
increases
Total pressure is:
measured parallel to the local stream
1/2ρV²
static pressure minus dynamic pressure
static pressure plus dynamic pressure
static pressure plus dynamic pressure
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 =
ρ = P/RT
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.”
“For every action there is an equal and opposite reaction.”
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
False
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
perpendicular to the surface that any air molecules collide with.
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
created when a force is applied at some distance from an axis or fulcrum, producing rotation about that point
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
all weight is concentrated
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
the ratio of the aircraft weight to the surface area of the wing
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.
is a line drawn halfway between the upper and lower surface of an airfoil.
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 measure of the wing along the chord line, from the leading edge to the trailing edge
Which formula or equation describes the relationship between force (F), acceleration (a) and mass (m)?
F = ma
a = Fm
m = Fa
F = m/a
F = ma
The angle of attack of a wing is the angle between the wing’s cord and the horizon
True
False
False
The axis is which the aircraft nose moves left or right about the center of gravity
pitch
yaw
center
roll
yaw
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
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
A _________ airfoil produces lift at zero degrees angle of attack.
symmetric
tapered
dihedral
positively cambered
positively cambered
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
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
Velocity and AOA are ____________ related in level flight
Directly
Not at all
Inversely
inversely
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
As the AOA increases, the center of lift ___________.
Moves rearward
Moves forward
Stays Stationary
moves forward
When an aircraft flies more slowly, more AOA is needed, when it flies faster less AOA is needed
true
false
true
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
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
AOA is the most important factor in the CL and the easiest for the pilot to change
true
false
true
The Center of Pressure is the point on the wing where the vectors of lift and drag act
true
false
true
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
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
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
Drag that is produced simply due to the production of lift is called ________.
Interference Drag
Form Drag
Induced Drag
Viscous Drag
induced drag
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
Streamlining shapes and increasing _________ are useful methods of reducing form drag.
Angle of Attack
Viscous Drag
Velocity
Frontal Area
Viscous Drag
Total drag is composed of ____________.
upwash and downwash
form and interference drag
parasite and induced drag
thrust and lift
parasite and induced drag
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.
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
Drag that is created by mixing airstreams between components is called _________.
Form Drag
Interference Drag
Viscous Drag
Induced Drag
Interference Drag
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
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
In a jet aircraft, as velocity increases, thrust available _________.
Decreases
Stays the same
Increases
stays the same
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
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
A thrust required curved can be use for various, weights, altitudes and configurations.
true
false
false
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
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
In equilibrium flight, thrust must ____________ drag.
be less than
be equal to
be greater than
be equal to
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
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
For a jet, power available increases linearly with an increase of velocity.
true
false
true
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
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.
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
Output from an engine in a propeller driven aircraft is called
Shaft Horsepower
Centrifugal Horsepower
Brake Horsepower
Thrust Horsepower
Shaft Horsepower
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
Maximum power available occurs at the full throttle setting.
true
fasle
true
For both jet and propeller driven aircraft, as air density decreases, thrust ________.
Increases
Stays the same
Decreases
Decresases
Output from a propeller is called
Shaft Horsepower
Brake Horsepower
Thrust Horsepower
Centrifugal Horsepower
Thrust Horsepower
Propeller Efficiency is determined by Thrust Horsepower divided by Shaft Horsepower
true
false
true
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
In a propeller driven airplane, as velocity increases, thrust available ______.
Decreases
Stays the same
Increases
decreases
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
Power on stall speed will be _______________ power off stall speed
faster than
the same as
lower than
lower than
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
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
The slotted flap is more advantageous than a plain flap because air passing through the slot aids in boundary layer control
true
false
true
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
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
Most slats increase lift by increasing the wing’s camber
true
false
false
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
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
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
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
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
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
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
How can you tell the difference between a spin and a spiral?
Airspeed
Roll rate
Rate of descent
Pitch attitude
Airspeed
It is impossible for an aircraft to enter an inverted spin
True
False
False
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
A spin is an aggravated stall that results in autorotation
True
False
True
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
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.
Poststall gyrations are dependent upon an aircraft’s _________.
weight
airspeed
CG
G loa
airspeed
An aircraft’s spin axis is always located in the center of the fuselage at the 50% cord line.
true
false
false
What is usually the most effective control for stopping the autorotation
Rudder
Elevators
Aileron
Rudder
