PoF Flashcards
Provided that there is no flow separation and no compressibility effects, the location of the aerodynamic centre (AC) _____ .
1- is at approximately 50% chord, regardless of the angle of attack
2- is at approximately 25% chord, regardless of the angle of attack
3- depends on the angle of attack
4- moves forward with an increasing angle of attack
is at approximately 25% chord, regardless of the angle of attack
= Point at which pitching moment does not vary with AoA
The wing is called anhedral if ______.
1- the wing tip and the root are on the same level
2- its wing tip is higher than the wing root
3- its wing root is higher than the tip
4- the line of the 25% chord is at the angle to the root chord
its wing root is higher than the tip
Dihedral angle = Angle between forizontal plane and wing suface at the tip
-Dihedral wing (angle > 0º) = Tip higher than root / root lower than tip
-Anhedral wing (Angle < 0º) = Tip lower than root / root higher than tip
Which is the correct definition of the dihedral angle?
1- The dihedral angle is the angle between the horizontal and the wing surface
2- The dihedral angle is the angle between the line of the 25% chord and the perpendicular to the root chord
3- The dihedral angle is the angle between the chord line and the horizon
4- The dihedral angle is the angle between the leading and trailing edge of the wing
The dihedral angle is the angle between the horizontal and the wing surface
Dihedral angle = Angle between forizontal plane and wing suface at the tip
-Dihedral wing (angle > 0º) = Tip higher than root / root lower than tip
-Anhedral wing (Angle < 0º) = Tip lower than root / root higher than tip
What are the parameters affecting the density? Select the most complete answer.
1- All answers are correct
2- Static pressure
3- Temperature
4- Humidity
All answers are correct
Higher pressure = Higher density
Higher temperature = Lower density
Higher humidity = Lower density
The angle of incidence is ____.
1- the angle between the line of 25% chord and the perpendicular to the root chord
2- the angle between the relative airflow and the wing chord line
3- the angle between the chord line and the horizon
4- the angle between the aircraft’s longitudinal axis and the wing chord line
the angle between the aircraft’s longitudinal axis and the wing chord line
Angle of incidence = the angle between the aircraft’s longitudinal axis and the wing chord line
Sweep angle = the angle between the line of 25% chord and the perpendicular to the root chord
Angle of Attack = the angle between the relative airflow and the wing chord line
Pitch angle = the angle between the chord line and the horizon
What is the SI unit of pressure?
1- Newton [N]
2- Pascal [Pa]
3- psi
4- bar
Pascal [Pa]
Newton (N) = FORCE
* Which statement describes the aerodynamic centre (AC)?*
1- It is the point where the velocity is reduced to zero
2- It is the point where the resultant aerodynamic force acts
3- It is the point where the pitching moment coefficient does not vary with the angle of attack
4- It is the point where the aeroplane’s lateral axis intersects with the centre of gravity
It is the point where the pitching moment coefficient does not vary with the angle of attack
Stagnation point = It is the point where the velocity is reduced to zero
Center of pressure point = It is the point where the resultant aerodynamic force acts
Mean aerodynamic chord (MAC) = It is the point where the aeroplane’s lateral axis intersects with the centre of gravity
Which are the components of the profile drag?
1- Pressure and induced drag
2- Skin friction, pressure and wave drag
3- Skin friction and wave drag
4- Skin friction and pressure drag
Skin friction and pressure drag
-Total (profile) drag = Pressure drag + Skin drag
-SKIN DRAG –> developed at the boundary layer ( where air velocity goes from zero at the surface to the value of undisturbed airflow):
-Airflow at the boundary layer of the leading edge is LAMINAR w/ less change in velocity = Less skin drag
-Airflow at the boundary layer of the trailing edge is TURBULENT w/ more change in velocty = Higher skin drag
-PRESSURE DRAG –> Results from differnce between leading (higher) and trailing (lower) edges.
How can the stagnation point be described?
1- It is the point of intersection of the total aerodynamic force and the chord line
2- It is the point where the velocity is reduced to zero
3- It is the point, relative to which the sum of all moments is independent of the angle of attack
4- It is the point of intersection of the thrust vector and the chord line
It is the point where the velocity is reduced to zero
Stagnation point:
= Point where velocity of relative airflow is reduzed to zero
-Static pressure reaches maximum value
-Icing is most likely to form aroudn this point
-Depends on AoA –> At highet AoA it moves to the lower surface!
In a symmetrical aerofoil, the mean camber line is ____.
1- collinear with the cord line
2- collinear with the upper surface
3- collinear with the lower surface
4- perpendicular to the relative airflow
collinear with the cord line
Symmetrical wing –> Cambe rline = Chord line; Center of pressure does not change w/ AoA and coincidental w/ aerodynamic center
Positive camber = Camber line higher than chord line
Negative camber = Camber line lower than chord line
What are the factors influencing the induced drag? I - Angle of incidence, II - Airspeed, III - Wingspan, IV - Aspect ratio, V - Lift magnitude
1- II, IV, V
2- I, III
3- I, II, III, IV, V
4- II, III, V
II, IV, V
Airspeed; Aspect ratio; Lift magnitude
How to reduce induced drag / wake turbulence / tip vortices?
- Higher aspect ratio
- Less wingspan
- Higher speed
- Lower mass
- Lower AoA
- Less lift
- Winglets
- Wing shape –> Eliptical wing
- Fit wing with tip tank (weight on the tip)
- Configuration –> use of lift augmentation devices (clean config is worse!!!)
With regard to changing weight, which of the following statements is correct?
1- The parasite drag does not depend on the weight, the induced drag increases with weight
2- The parasite drag increases the weight, the induced drag decreases with weight
3- The parasite drag and the induced drag increase with weight
4- No other answer is correct
The parasite drag does not depend on the weight, the induced drag increases with weight
TOTAL (Profile) DRAG =
INDUCED DRAG + PARASITE DRAG
Weight:
–> Affects induced drag (more weight = more drag) but not parasite drag
Speed:
–> Higher speed = Lower induced drag
–> Higher speed = Higher parasite drag
Parasite drag (“PIS”):
-Pressure (form) drag –> Originates from pressure differential between leading (higher) and trailing (lower) edges; Depends on cross section area (higher area = higher drag) and shape (3:1 = best)
-Interference drag –> Originates from boundary layer interference at junction of different parts ; Reduced by fillets
-Skin (friction) drag –> Originates from fluid viscosity (leading edge = laminar flow = less drag; trailing edge = turbulent flow = more drag); Depends on surface roughness (more rough = more drag)
Trailing edge vortices___ .
1- are stronger at lower angles of attack
2- are present only at high angles of attack
3- are not influenced by the angle of attack
4- are stronger at higher angles of attack
are stronger at lower angles of attack
How to reduce induced drag / wake turbulence / tip vortices?
- Higher aspect ratio
- Less wingspan
- Higher speed
- Lower mass
- Lower AoA
- Less lift
- Winglets
- Wing shape –> Eliptical wing
- Fit wing with tip tank (weight on the tip)
- Configuration –> use of lift augmentation devices (clean config is worse!!!)
The wake turbulence vortices tend to____ .
1- stay on the same level
2- ascend to a higher level
3- descend to a lower level
4- stay on the ground level
descend to a lower level
Lenght up to 9 NM
Drift downwards about 500 - 1000ft below aircraft flight path
How can the induced drag be reduced? Select the most complete answer.
1- By winglets
2- By greater wingspan
3- By decreasing the mass on the wing tips
4- All answers are correct
By winglets
How to reduce induced drag / wake turbulence / tip vortices?
- Higher aspect ratio
- Less wingspan
- Higher speed
- Lower mass
- Lower AoA
- Less lift
- Winglets
- Wing shape –> Eliptical wing
- Fit wing with tip tank (weight on the tip)
- Configuration –> use of lift augmentation devices (clean config is worse!!!)
Regarding the spanwise flow on the wing_____ .
1- the air flows from the root to the tip on the lower and the upper side of the wing
2- on the lower side of the wing the air flows from the wing root to the tip, and on the upper side from the tip to the root
3- the air flows from the tip to the root on the lower and the upper side of the wing
4- on the lower side of the wing the air flows from the wing tip to the root, and on the upper side from the root to the tip
on the lower side of the wing the air flows from the wing root to the tip, and on the upper side from the tip to the root
The length of the wake turbulence can reach up to ____.
1- 9 NM
2- 12 NM
3- 20 NM
4- 1 NM
9 NM
Lenght up to 9 NM
Drift downwards about 500 - 1000ft below aircraft flight path
What are the factors influencing wake turbulence? I - Weight, II - Airspeed, III - Wingspan, IV - Taper ratio, V - angle of attack, VI - pitch attitude, VII - aircraft’s configuration
1- I, II, IV, V
2- I, II, III, V, VII
3- I, III, V, VI
4- II, IV, VI, VII
I, II, III, V, VII
Weight; Airspeed; Wingspan; AoA; configuration
How to reduce induced drag / wake turbulence / tip vortices?
- Higher aspect ratio
- Less wingspan
- Higher speed
- Lower mass
- Lower AoA
- Less lift
- Winglets
- Wing shape –> Eliptical wing
- Fit wing with tip tank (weight on the tip)
- Configuration –> use of lift augmentation devices (clean config is worse!!!)
Which type of drag will increase if the wing surface becomes contaminated? Select the most complete answer.
1- Induced drag
2- All answers are correct
3- Interference drag
4- Skin friction drag
Skin friction drag
TOTAL (Profile) DRAG =
INDUCED DRAG + PARASITE DRAG
Weight:
–> Affects induced drag (more weight = more drag) but not parasite drag
Speed:
–> Higher speed = Lower induced drag
–> Higher speed = Higher parasite drag
Parasite drag (“PIS”):
-Pressure (form) drag –> Originates from pressure differential between leading (higher) and trailing (lower) edges; Depends on cross section area (higher area = higher drag) and shape (3:1 = best)
-Interference drag –> Originates from boundary layer interference at junction of different parts ; Reduced by fillets
-Skin (friction) drag –> Originates from fluid viscosity (leading edge = laminar flow = less drag; trailing edge = turbulent flow = more drag); Depends on surface roughness (more rough = more drag)
Which of the following statements is correct?
1- The induced drag increases and the parasite drag decreases with airspeed
2- The induced drag and the parasite drag increase with airspeed
3- The induced drag decreases and the parasite drag increases with airspeed
4- The induced drag and the parasite drag decrease with airspeed
The induced drag decreases and the parasite drag increases with airspeed
TOTAL (Profile) DRAG =
INDUCED DRAG + PARASITE DRAG
Weight:
–> Affects induced drag (more weight = more drag) but not parasite drag
Speed:
–> Higher speed = Lower induced drag
–> Higher speed = Higher parasite drag
Parasite drag (“PIS”):
-Pressure (form) drag –> Originates from pressure differential between leading (higher) and trailing (lower) edges; Depends on cross section area (higher area = higher drag) and shape (3:1 = best)
-Interference drag –> Originates from boundary layer interference at junction of different parts ; Reduced by fillets
-Skin (friction) drag –> Originates from fluid viscosity (leading edge = laminar flow = less drag; trailing edge = turbulent flow = more drag); Depends on surface roughness (more rough = more drag)
Where can the vortex generator be found?
1- On the upper side of the wing near the leading edge
2- On the upper side of the wing near the trailing edge
3- On the lower side of the wing near the trailing edge
4- On both sides of the wing near the trailing edge
On the upper side of the wing near the leading edge
VORTEX GENERATORS:
-Located on the upper surface of wing near the leading edge
-Transfer energy from free airflow to boundary layer (energizes boundary layer), reducing separation and decreasing stall speed
-Advantages:
-Better control surface effectiveness
-Smoother ride in turbulence
-Less noise
-Decrease stall speed
-Disadvantages:
-Decrease cruise speed
-Harder ice and snow clearence
Which type of trailing edge flaps offers the highest CLMAX increase?
1- Fowler flap
2- Slotted flap
3- Plain flap
4- Split flap
Fowler flap
Fowler (highest CLmax and lowest drag)
> Slotted
> Split
> Plain (used in light aircraft)
Which of the following are high lift devices? I - Trailing edge flaps, II - Leading edge slats, III - Spoilers, IV - Krueger flaps, V - Ailerons
1- I, II, IV
2- I, II, III, IV
3- II, IV, V
4- I, III, III, V
I, II, IV
CL max may be increased by:
-Boundary layer control
-Leading edge slats or Krueger flaps
-Trailing edges flaps
What is the effect of slats extension on the take-off and landing distances?
1- The take-off and landing distances decrease with slats extended
2- The take-off and landing distances increase with slats extended
3- Slats extension does not influence the take-off and landing distances
4- The take-off distance increases and landing distance decreases with flaps extended
The take-off and landing distances decrease with slats extended
Slats and Flaps have the same effects!
During landing:
-Lower landing speed
-Steeper descent angle w/o airspeed increase
-Decrease landing distance
During T/O:
-T/O distance decrease
-Decreased climb angle
-Increased glide angle
The aged airframe will produce _____ as compared to a new airframe.
1- increased interference drag
2- increased induced drag
3- increased skin friction drag
4- increased form drag
increased skin friction drag
What is the effect of flaps extension on the take-off and landing distances?
1- Flaps extension does not influence the take-off and landing distances
2- The take-off and landing distances increase with flaps extended
3- The take-off and landing distances decrease with flaps extended
4- The take-off distance increases and landing distance decreases with flaps extended
The take-off and landing distances decrease with flaps extended
Slats and Flaps have the same effects!
During landing:
-Lower landing speed
-Steeper descent angle w/o airspeed increase
-Decrease landing distance
During T/O:
-T/O distance decrease
-Decreased climb angle
-Increased glide angle
Which of the following statements regarding the effect of flap extension is correct?
1- The aeroplane with flaps extended will have a decreased climb angle and glide angle
2- The aeroplane with flaps extended will have an increased climb angle and decreased glide angle
3- The aeroplane with flaps extended will have increased climb angle glide angle
4- The aeroplane with flaps extended will have a decreased climb angle and increased glide angle
The aeroplane with flaps extended will have a decreased climb angle and increased glide angle
Slats and Flaps have the same effects!
During landing:
-Lower landing speed
-Steeper descent angle w/o airspeed increase
-Decrease landing distance
During T/O:
-T/O distance decrease
-Decreased climb angle
-Increased glide angle
With regard to the ground effect, below which height the reduction in the induced drag becomes significant?
1- Below height equal to the wing span
2- Below height equal to a quarter of the wing span
3- Below 1000 ft
4- Below height equal to the half of the wing span
Below height equal to the half of the wing span
With regard to the ground effect, which statement is correct?
1- Lift and the induced drag decrease
2- Lift increases and induced drag decreases
3- Lift and the induced drag increase
4- Lift decreases and the induced drag increases
Lift increases and induced drag decreases
GROUND EFFECT:
-When the height is less than half the wingspan
-Heat decreased ground effect (less density)
-ENTERING GROUND EFFECT:
(“LEID Di has double DD’s but Wants to Change”)
-L = Lift coefficient increase (higher CL/CD) -E = Effective AoA increase (with decrease in critical AoA which may lead to stall) -I = Induced AoA decrease -D = Downwash angle decrease -Di = Drag Induced decrease (less wingtip vortices) DD = Decreased decceleration (if throttle is not reduced, aircraft may climb above desired glide path) W = Wing stall (leads to heavy landing) C = Change in position error (ASI and altimeter underread)
* Which of the following are the effects of the ice formation on the wing? Select the most complete answer.*
1- Earlier separation
2- Increased skin friction drag
3- CLMAX and the critical angle of attack decrease
4- All answers are correct
All answers are correct
Ice build-up locations:
-Leading edges and vertical and horizontal stabilizers
-Engine inlets
-Propellers
-Measurement equipment
-Windows
Ice build-up effects:
-Increase surface roughness –> Increase skin drag (total drag increases by 40%)
-CLMAX and the critical angle of attack decrease (lift decreased by 30%)
-Earlier flow separation (w/ higher stall speed)
Which of the following statements about the laminar boundary layer is NOT true?
1- In a laminar boundary layer, the fluid flow is smooth, without any turbulence or vortices
2- The laminar flow carries more energy than the turbulent one and is thus less susceptible to separation
3- In a laminar boundary layer, the fluid speed decreases slowly as it gets closer to the wall
4- A laminar boundary layer produces little drag
The laminar flow carries more energy than the turbulent one and is thus less susceptible to separation
BOUNDARY LAYER:
= Layer where airflow velocity changes from zero at the aerofoil’s surface to the value o undisturbed airflow
-Boundary layer thickness = From surface to 99% velocity of undisturbed airflow (increases w/ distance from leading edge)
-Transition point = Laminar boundary layer turns into turbulent boundary layer
-LAMINAR boundary layer –> Thinner; less energy; less friction drag; more susceptible to flow separation
-TURBULENT boundary layer –> Thicker; more energy; more friction drag; less susceptible to flow separation
What is the boundary layer transition?
1- It is the transition between the turbulent boundary layer and the undisturbed airflow
2- It is the transition between the laminar boundary layer and the undisturbed airflow
3- It is the transition from the laminar boundary layer to the turbulent boundary layer
4- It is the transition from the turbulent boundary layer to the laminar boundary layer
It is the transition from the laminar boundary layer to the turbulent boundary layer
BOUNDARY LAYER:
= Layer where airflow velocity changes from zero at the aerofoil’s surface to the value o undisturbed airflow
-Boundary layer thickness = From surface to 99% velocity of undisturbed airflow (increases w/ distance from leading edge)
-Transition point = Laminar boundary layer turns into turbulent boundary layer
-LAMINAR boundary layer –> Thinner; less energy; less friction drag; more susceptible to flow separation
-TURBULENT boundary layer –> Thicker; more energy; more friction drag; less susceptible to flow separation
What change in the attitude of the aeroplane is caused by one wing stalling before the other?
1- The uncommanded rolling motion towards the stalled wing
2- Uncommanded rolling motion away from the stalled wing
3- Uncommanded pitch-down
4- Uncommanded pitch-up
The uncommanded rolling motion towards the stalled wing
Stall characteristics:
- Reduced effectiveness of flight controlls
- Uncommanded pitch down (due to loss of lift)
- Uncommanded roll (due to one wing stalling before the other one –> towards the stalled wing)
Why does special attention need to be paid when using ailerons in a nearly-stalled aeroplane?
1- Deflecting the aileron down increases the aerofoil camber, which can cause a portion of the wing to stall, reversing the effect of aileron deflection
2- Due to the attitude of the aeroplane, the access to the cockpit controls is more difficult for the pilot
3- Deflecting the aileron down increases the aerofoil camber, which very strongly increases the effectiveness of the ailerons at high angles of attack
4- With an increase in Angle of Attack, the Centre of Pressure moves towards the trailing edge, which means that the Centre of Pressure can move to the hinge of the aileron, locking it in place
Deflecting the aileron down increases the aerofoil camber, which can cause a portion of the wing to stall, reversing the effect of aileron deflection
What is the effect of increasing the Angle of Attack (AoA) on the location of the separation point?
1- As the AoA increases, the separation point moves forward
2- As the AoA increases, the separation point moves backwards
3- The location of the separation point does not depend on the AoA
4- With an increase in AoA, the separation point disappears
As the AoA increases, the separation point moves forward
SEPARATION POINT:
= Airflow stops following the curvature of the wing and starts moving freely
-At low AoA –> Separation point is located near the trailing edge
-As AoA increases –> Separation point moves forward
How does wing contamination affect the stalling speed?
1- Due to the reduced C_L, the stalling speed increases
2- Due to the reduced C_L, the stalling speed decreases
3- Due to the increased C_L, the stalling speed decreases
4- Due to the increased C_L, the stalling speed increases
Due to the reduced C_L, the stalling speed increases
WING CONTAMINATION:
-More surface roughness –> more skin drag (increased drag by 40%)
-Earlier flow separation
-Reduced CL max (decreased lift by 30%)
-Reduced critical AoA
-Increased stall speed
What is the separation point?
1- It is the transition from the laminar boundary layer to the turbulent boundary layer
2- It is the point where the airflow stops following the curvature of the wing and starts moving freely
3- It is the point on the aerofoil where the speed of airflow is 0
4- It is the point at which the fluid flow reverses direction
It is the point where the airflow stops following the curvature of the wing and starts moving freely
SEPARATION POINT:
= Airflow stops following the curvature of the wing and starts moving freely
-At low AoA –> Separation point is located near the trailing edge
-As AoA increases –> Separation point moves forward
Which of the following statements about the turbulent boundary layer is NOT true?
1- The turbulent flow carries more energy than the laminar flow, which makes it less susceptible to separation
2- The turbulent flow carries less energy than the laminar flow, which makes it more susceptible to separation
3- In a turbulent boundary layer, the fluid speed decreases rapidly near the wall
4- The turbulent boundary layer produces less drag
The turbulent boundary layer produces less drag
BOUNDARY LAYER:
= Layer where airflow velocity changes from zero at the aerofoil’s surface to the value o undisturbed airflow
-Boundary layer thickness = From surface to 99% velocity of undisturbed airflow (increases w/ distance from leading edge)
-Transition point = Laminar boundary layer turns into turbulent boundary layer
-LAMINAR boundary layer –> Thinner; less energy; less friction drag; more susceptible to flow separation
-TURBULENT boundary layer –> Thicker; more energy; more friction drag; less susceptible to flow separation
How and why does the stalling speed change in flight with a load factor n>1 compared to a straight and level flight?
1- Flying with a bank angle introduces a perpendicular component to the airflow over the wings, decreasing the generated lift and necessitating an increase in speed
2- With a higher load factor more lift is needed, so for a given maximum CL the speed must be increased to keep the aeroplane aloft
3- The centrifugal force helps the lift in overcoming the weight of the aircraft, and the stalling speed decreases
4- The stalling speed remains constant, as it only depends on the Angle of Attack of the wing
With a higher load factor more lift is needed, so for a given maximum CL the speed must be increased to keep the aeroplane aloft
STALL SPEED:
Vsr = Reference stall speed
Vs0 = Stall speed in landing configuration
Vs1 = Stall speed in specific configuration
Vs1g = Minimum speed at which lift = weight
Vs = √ load factor * ( (aircraft weight*2) / (density * surface of wings * CL max))
Load factor (n) = Lift / Weight = 1 / cos (bank angle)
n = 1 –> Steady straight level flight
n < 1 –> steady climb or descent
n > 1 –> HIGHER STALL SPEED –> gust, pulling out of a dive, turn
Factors that increase stall speed:
-More weight
-Swept wing / less wing surface area / higher wing loading
-Forward center of gravity
-High altitude (less desity)
-More bank angle
-Turbulence
-Icing
-Pulling out of a dive
-Less thrust
At what Angle of Attack (AoA) is the maximum CL achieved?
1- At the critical AoA
2- At the minimum drag coefficient AoA
3- At the best Lift/Drag (L/D) AoA
4- At the best glide endurance AoA
At the critical AoA
Optimum AoA (4º) = Max L/D
Critical AoA (16º) = Max Lift (CL)
How does icing affect the CL and stall speed?
1- Icing decreases C_L, which decreases the stall speed
2- Icing decreases C_L, which increases the stall speed
3- Icing increases C_L, which decreases the stall speed
4- Icing increases C_L, which increases the stall speed
Icing decreases C_L, which increases the stall speed
Ice build-up locations:
-Leading edges and vertical and horizontal stabilizers
-Engine inlets
-Propellers
-Measurement equipment
-Windows
Ice build-up effects:
-Increase surface roughness –> Increase skin drag (total drag increases by 40%)
-CLMAX and the critical angle of attack decrease (lift decreased by 30%)
-Earlier flow separation (w/ higher stall speed)
How does the flapper switch work?
1- As the Angle of Attack (AoA) increases, it deflects a flap on the fuselage which feeds a signal to the computer in the cockpit
2- It informs the pilot about the imminent stall by vibrating (or flapping) the control column
3- As the AoA increases, the stagnation point moves, and once it reaches the location of the flapper switch, the switch and the stall warning are activated
4- It informs the pilot about overspeeding the aircraft by vibrating (or flapping) the control column
As the AoA increases, the stagnation point moves, and once it reaches the location of the flapper switch, the switch and the stall warning are activated
STALL WARNING:
-Pre-stall buffet –> Most apparent phenomenon preceeding a stall –> = Quick oscillations caused by turbulent flow impinging on the horizontal stabilizer
-Flapper switch –> As the AoA increases, the stagnation point moves, and once it reaches the location of the flapper switch, the switch and the stall warning are activated
-Stall horn –> Most common in general aviation –> Hole in the wing. When AoA increases, it creates low pressure around the hole –> suction general airflow through the horn, making a sound
Stick shaker –> Activates at lower angle than stick pusher. It’s triggered by airspeed higher than Vs. Input from AoA and rate of AoA change.
How does flying through heavy rain influence the aeroplane’s performance?
1- When flying through heavy rain, the aeroplane’s weight slightly increases, the drag increases and the lift increases
2- When flying through heavy rain, the aeroplane’s weight slightly increases, the drag decreases and the lift increases
3- When flying through heavy rain, the aeroplane’s weight slightly increases, the drag increases and the lift decreases
4- When flying through heavy rain, the aeroplane’s weight slightly decreases, the drag decreases and the lift increases
When flying through heavy rain, the aeroplane’s weight slightly increases, the drag increases and the lift decreases
With rain:
-Aircraft weight increases by 2%
-Drag increases by 30%
-Lift decreases
Why are stabiliser aerofoils more susceptible to icing than the aerofoils found on the wings?
1- Because stabilisers aerofoils are thinner
2- Because stabilisers’ aerofoils are thicker
3- Because stabilisers’ aerofoils are symmetrical
4- Because stabilisers’ aerofoils are set at a lower angle of incidence and experience downwash from the wings
Because stabilisers aerofoils are thinner
What is the Holdover Time (HOT)?
1- It is a time duration for which the aeroplane is supposed to hold over a given waypoint in low-visibility conditions
2- It is the time for which the onboard supplies of anti-ice chemical products will last in icing conditions
3- It is a time for which the engines can be run at the max power, preventing the snow and ice from accumulating on the aeroplane
4- It is a time during which the anti-ice fluid prevents the snow and ice from accumulating on the aeroplane in given atmospheric conditions
It is a time during which the anti-ice fluid prevents the snow and ice from accumulating on the aeroplane in given atmospheric conditions
What is a super stall (also known as a deep stall)?
1- It is a stall that is unrecoverable, due to the excessive pitch-up moment and reduced elevator authority
2- It is a stall which is reached very fast, due to the excessive pitch-up rate of the aeroplane
3- It is a stall that is reached very slow, due to the low pitch-up rate of the aeroplane, which means it possibly can be undetected by the pilot
4- It is a stall that is reached at a low Angle of Attack (AoA) due to the aerodynamic properties of the aeroplane
It is a stall that is unrecoverable, due to the excessive pitch-up moment and reduced elevator authority
Why are stall speed margins used during aeroplane operations?
1- To improve the fuel efficiency during take-off and landing operations
2- To ensure the safety of operation in case of pilot error or an unaccounted difference in parameters affecting the stall speed
3- To protect the airframe from excessive loads generated by heavy maneuvres
4- To ensure compliance with ATC law requirements
To ensure the safety of operation in case of pilot error or an unaccounted difference in parameters affecting the stall speed
What is the purpose of stall warning systems?
1- They allow the pilot to monitor the Angle of Attack (AoA)
2- They inform the pilot about the loss of power in the engine
3- They prevent the aeroplane susceptible to the deep stall from entering it by physically moving the control column
4- They inform the pilot about the imminent stall
They inform the pilot about the imminent stall
How can the deployment of flaps cause the stall of the horizontal stabiliser?
1- Deployment of the flaps increases downwash from the wings, increasing the Angle of Attack (AoA) of the stabiliser, which can lead to a stall
2- Deployment of the flaps increases downwash from the wings, decreasing the Angle of Attack (AoA) of the stabiliser, which can lead to a stall
3- Deployment of the flaps increases the camber of the stabiliser, which can lead to a stall
4- Deployment of the flaps decreases the camber of the stabiliser, which can lead to a stall
Deployment of the flaps increases downwash from the wings, increasing the Angle of Attack (AoA) of the stabiliser, which can lead to a stall
Which of these statements about the spin is NOT true?
1- In a spin, the Angle of Attack (AoA) is the same on both wings
2- In a spin, the aeroplane descends in a rotational movement
3- The spin must be preceded by the stall
4- In a spin, both wings are stalled
In a spin, the Angle of Attack (AoA) is the same on both wings
SPIN:
-Always preceeded by stall
-Both wings are stalled, but one more than the other (different AoA)
-In a spin, the aeroplane descends in a rotational movement
-Turn indicator shows direction of rotation
-Slip/skid ball is unreliable
Factors causing spin:
-Uncoordinated maneuvers
-Center of gravity lateral displacement
-Abrupt control inputs at high AoA
Spin phases:
1- Incipient
2- Developed
3- Recovery –> decrease power to idle –> Neutral ailerons –> Full opposite rudder –> Pitch down (yoke forward)
Which of the following statement about static stability is correct? Select the most complete answer.
1- Static stability is classified as positive and negative static stability only
2- All answers are correct
3- Static stability considers the resulting motion of aircraft
4- Static stability is the initial response of an aircraft
Static stability is the initial response of an aircraft
STATIC STABILITY:
= Initial response after disturbance
-Positive –> Returns to original attitude
-Neutral –> Retains disturbed attitude
-Negative –> Worsens disturbed attitude
DYNAMIC STABILITY:
= Resulting motion over time
-Positive –> oscillations dampen out over time
-Neutral –> Amplitude of oscillations remains constant
-Negative –> Amplitude of oscillations increases over time
What is the purpose of the horizontal stabiliser with respect to aircraft stability?
1- The horizontal stabiliser provides stabilising pitching moment
2- The horizontal stabiliser provides destabilising pitching moment
3- The horizontal stabiliser has no effect on stability
4- The horizontal stabiliser increases the aircraft CG movement
The horizontal stabiliser provides stabilising pitching moment
Which opposes the wing’s destabilizing pitch down moment
What is the distance between the Neutral point and the aircraft CG in straight, level flight called?
1- CG aft limit
2- Manoeuvre margin
3- Static margin
4- CG forward limit
Static margin
STATIC MARGIN:
= Distance between CG and neutral point ( % MAC) –> Higher static margin = aircraft more stable and less maneuvrable
NEUTRAL POINT:
= Point where destabilizing wing moment and stabilizing stabilizer moment are equal!
From front to aft: (“CiNEMA”) –> CG –> NEutral point –> MAneuvre point
CG aft = Increase maneuvrability; Decrease stability (wing destabiliting moment > stabilizer stabilizing moment)
CG forward = Decrease maneuvrability; Increase stability ( stabilizer stabilizing moment > wing destabiliting moment)
Which of the following statements about the trimmed flight are correct? 1. The weight is balanced by the lift
2. The drag is balanced by the thrust 3. Aerodynamic moments about the aircraft CG is zero.
1- Only 1 and 2 are correct
2- 1, 2 and 3 are correct
3- Only 2 and 3 are correct
4- Only 1 and 3 are correct
1, 2 and 3 are correct
Which stabilities of the aircraft are coupled?
1- Directional and longitudinal stability
2- Directional and lateral stability
3- Lateral and longitudinal stability
4- Longitudinal, directional and lateral stability
Directional and lateral stability
Directional (yaw) –> Spiral dive
Lateral (roll) –> Dutch roll
Which type of static stability will make the aircraft retain the disturbed attitude?
1- Negative static stability
2- Positive static stability
3- Neutral static stability
4- Dynamic stability
Neutral static stability
STATIC STABILITY:
= Initial response after disturbance
-Positive –> Returns to original attitude
-Neutral –> Retains disturbed attitude
-Negative –> Worsens disturbed attitude
DYNAMIC STABILITY:
= Resulting motion over time
-Positive –> oscillations dampen out over time
-Neutral –> Amplitude of oscillations remains constant
-Negative –> Amplitude of oscillations increases over time
Which stability considers the resulting motion of an aircraft over time? Select the most complete answer
1- Static stability
2- Dynamic stability
3- All answers are correct
4- No other answer is correct
Dynamic stability
STATIC STABILITY:
= Initial response after disturbance
-Positive –> Returns to original attitude
-Neutral –> Retains disturbed attitude
-Negative –> Worsens disturbed attitude
DYNAMIC STABILITY:
= Resulting motion over time
-Positive –> oscillations dampen out over time
-Neutral –> Amplitude of oscillations remains constant
-Negative –> Amplitude of oscillations increases over time
Which of the following statement regarding the behaviour of an aircraft in a spiral dive is/are correct? Select the most complete answer.
1- All answers are correct
2- The bank angle of the aircraft increases
3- The altitude of the aircraft decreases
4- The nose low-pitch attitude increases
All answers are correct
SPIRAL DIVE: (“Spain Yawkes :/ “)
-Aperiodic motion
-Strong directional (yaw) stability
-Weak lateral (roll) stability
-Stable dive = wings level
-Neutral dive = Maintains bankg angle
-Unstable (spiral divergence) = Bank angle increases
DUTCH ROLL: (“Dutch rocks n’ roll :D”)
-Periodic motion
-Strong lateral (roll) stability
-Weak directional (yaw) stability
-More likely at thigh altitude /mach
Which of the following statement is true about long period oscillation?
1- The pilot cannot easily control this motion
2- Long period oscillation is a progressive exchange of kinetic and potential energy
3- Specific aerodynamic provisions are required to counteract long period oscillation
4- Long period oscillation is one of the basic modes of static stability
Long period oscillation is a progressive exchange of kinetic and potential energy
PHUGOID (LONG-PERIOD OSCILLATION):
-1-2 min
-Weak damping
-High airspeed variation
-High altitude variation
-Slow AoA changes
SHORT-PERIOD OSCILLATION:
-1-2s
-Strong damping
-Constant airspeed
-Constant altitude
-Rapid AoA changes
What happens if the manoeuvrability of an aircraft increases?
1- Stability decreases
2- Stability also increases
3- Stability neither increase nor decrease
4- Pilot input to control column increases
Stability decreases
Stability opposed maneuvrability!
STATIC MARGIN:
= Distance between CG and neutral point ( % MAC) –> Higher static margin = aircraft more stable and less maneuvrable
NEUTRAL POINT:
= Point where destabilizing wing moment and stabilizing stabilizer moment are equal!
From front to aft: (“CiNEMA”) –> CG –> NEutral point –> MAneuvre point
CG aft = Increase maneuvrability; Decrease stability (wing destabiliting moment > stabilizer stabilizing moment)
CG forward = Decrease maneuvrability; Increase stability ( stabilizer stabilizing moment > wing destabiliting moment)
How does the required download on the horizontal stabiliser change with the CG moving forward?
1- It increases
2- It decreases
3- It doesn’t change
4- It decreases or increases, depending on the airspeed
It increases
Forward CG limit is determined by amount of pitch control available –> If CG exceeds forward limit, the tailplane may fail to produce enough downforce (nose-up pitching moment) to counter-act the wing’s nose down moment!
If the control wheel is turned to the right_____, .
1- the right aileron is deflected up and the left aileron is deflected up
2- the right aileron is deflected down and the left aileron is deflected down
3- the right aileron is deflected up and the left aileron is deflected down
4- the right aileron is deflected down and the left aileron is deflected up
the right aileron is deflected up and the left aileron is deflected down
AILERONS:
-provide lateral control by producing different amount of lift on both wings
-Aircraft turns towards the side of the upward deflected aileron due to less lift on that wing
-Upgoing aileron also produces less drag –> adverse yaw = yaw in opposite direction of turn
-Aileron defflection does NOT give a specific roll displacement but rather a given roll rate! –> higher wingspan = lower roll rate
How can the adverse yaw be reduced? Select the most complete answer.
1- By using roll spoilers
2- By Frise ailerons
3- All answers are correct
4- By the differential ailerons
All answers are correct
During roll, the upgoing aileron also produces less drag –> adverse yaw = yaw in opposite direction of turn
The horizontal stabiliser positioned at neutral at cruising speed and with normal CG position ____ .
1- will not produce any load
2- will produce an upload
3- will produce a download
4- will produce download or upload depending on the speed
will produce a download
Horizontal stabilizer produced a download force leading to a nose pitch up moment to counter-act the wings’ nose pitch down moment!
Which statement about the effect of using a trim tab on the hinge moment is true?
1- The trim tab decreases the hinge moment
2- The trim tab does not affect the hinge moment
3- The trim tab increases the hinge moment
4- The trim tab balances the hinge moment
The trim tab balances the hinge moment
Trim tab = balances hinge moment
Balance tab = decreases hinge moment
Adjustable trim tab = On rudder and elevator –> fitted to trailling edge of control surface, that moves in opposite direction
Fixed trim tab = On ailerons –> adjusted only on the ground
**The rotation about the lateral axis is known as _____ **.
1- yawing
2- pitching
3- banking
4- rolling
pitching
All the axes of the aeroplane must pass through ____.
1- the Centre of Gravity
2- the Centre of Pressure
3- the Aerodynamic Centre
4- the geometric centre of the fuselage
the Centre of Gravity
How does the wingspan influence the roll rate for a given aileron deflection?
1- The greater the wingspan the lower the roll rate
2- The greater the wingspan the greater the roll rate
3- It does not influence the roll rate
4- Greater wingspan increases the roll rate, but only if the aeroplane is laterally unstable
The greater the wingspan the lower the roll rate
AILERONS:
-provide lateral control by producing different amount of lift on both wings
-Aircraft turns towards the side of the upward deflected aileron due to less lift on that wing
-Upgoing aileron also produces less drag –> adverse yaw = yaw in opposite direction of turn
-Aileron defflection does NOT give a specific roll displacement but rather a given ROLL RATE! –> higher wingspan = lower roll rate
Which is the correct definition of the longitudinal axis?
1- The axis directed forward, along the fuselage reference line, passing through CP
2- The axis directed forward, along the fuselage reference line, passing through CG
3- The axis parallel to the line connecting wingtips, passing through CG
4- The axis parallel to the line connecting wingtips, passing through CP
The axis directed forward, along the fuselage reference line, passing through CG
The angle of the rudder deflection ____.
1- corresponds to a specific yaw displacement
2- corresponds to a specific yaw rate change
3- does not correspond to any specific yaw displacement or rate
4- is not limited
corresponds to a specific yaw displacement
Angle of rudder or elevator defflection corresponds to a specfic pitch and yaw displacement
While….
Angle of aileron deflection corresponds to a given roll rate!
What is true about the never exceed speed VNE? Select the most complete answer.
1- VNE is set below the VD to enable the upset recovery
2- VNE is relevant for small aircraft
3- All answers are correct
4- VNE exceedance may result in structural damage or failure
All answers are correct
VS1 = Stall speed –> Minimum speed at which aircraft is controllable
Va = Maneuvering speed –> Va = VS1 x (√n); Va < Vc Max speed for control surface full deflection. Depends on mass and pressure altitude.
Vb = Design speed for max gust intensity –> 66ft/s gust. Flying through turbulence at Vb provides max protectiong from damage
Vc = Design cruising speed –> Used to assess strenght requirements in cruise. 50ft/s gust
Vd = Design Dive speed –> Highest speed the aircraft is designed to achieve. 25 ft/s gust
Vra = Speed Rough Air –> recommended turbulence penetration speed
Vne = Never Exceed speed –> <0.9*Vd to enable upset recovery; relevant to small aircraft; marked as red line in ASI;
Vfe = Flaps Extended speed–> Max speed w/ flaps extended; end of white arc on ASI
How is the ultimate load defined?
1- The ultimate load is the maximum load that doesn’t result in critical failure of the structure
2- The ultimate load is the maximum load that is expected during the operations
3- The ultimate load is the load that leads to the failure of the structure
4- The ultimate load is the load for the maximum landing weight
The ultimate load is the load that leads to the failure of the structure
Ultimate load = Load that leads to failure of the structure
Limit load = Max load expected during operations
Factor of safety = ultimate load / limit load; 1,5x load factor!
How is the equivalent airspeed (EAS) defined?
1- EAS is the airspeed of the aircraft relative to the airmass in which it is flying at ISA conditions
2- EAS is the airspeed of the aircraft relative to the airmass in which it is flying
3- None of the answers is correct
4- EAS is an airspeed at sea level ISA conditions which generates the same total pressure at TAS at an altitude at which the aircraft is flying
None of the answers is correct
Equivalent Air Speed
= Airspeed that generates same dynamic pressure as TAS at an altitude which the aircraft is flying
-Used to: Predict aerodynamic load and Predict stalling
= EAS = TAS * √(actual density / std sea lvl density)
How does the wing loading affect the increase in load factor due to the gust?
1- High wing loading results in a lower increase of load factor due to the gust
2- High wing loading results in a greater increase of load factor due to the gust
3- Low wing loading results in a lower increase of load factor due to the gust
4- The wing loading does not affect the increase in load factor due to the gust
High wing loading results in a lower increase of load factor due to the gust
Gust load factor decreases when:
-AoA increases
-altitude increases
-Mass increases
-Wing load factor increases
-Speed decreases
-Lower wing area
-Lower aspect ratio
How to prevent the flutter of the ailerons? Select the most complete answer.
1- By making the ailerons irreversible
2- All answers are correct
3- By attaching a mass before the hinge line
4- By moving the CG to, or ahead of the hinge line
All answers are correct
FLUTTER:
= Quick uncontrolled oscillations of the surface
= Most dangerous effect of aeroelasticity
- Dependent on IAS
-Caused by:
-Bending + torsion of wing
-Aeroelastic coupling
-Cyclic deformations
-Prevented by:
-Wing CG ahead of torsional axis
-Increase wing stiffness (by placing leading edge spar)
-Wing mounted engines ahead of wing CG
-Mass balance of control surface (to move CG ahead of hinge line)
-Fully powered controls (irreversible, w/o manual override)
What will be the design manoeuvring speed if the VS = 50 kt and n = 6?
1- 122 kt
2- 137 m/s
3- 122 km/h
4- None of the answers is correct
122 kt
VS1 = Stall speed –> Minimum speed at which aircraft is controllable
Va = Maneuvering speed –> Va = VS1 x (√n); Va < Vc Max speed for control surface full deflection. Depends on mass and pressure altitude.
Vb = Design speed for max gust intensity –> 66ft/s vertical gust. Flying through turbulence at Vb provides max protectiong from damage
Vc = Design cruising speed –> Used to assess strenght requirements in cruise. 50ft/s vertical gust
Vd = Design Dive speed –> Highest speed the aircraft is designed to achieve. 25 ft/s vertical gust
Vra = Speed Rough Air –> recommended turbulence penetration speed
Vne = Never Exceed speed –> <0.9*Vd to enable upset recovery; relevant to small aircraft; marked as red line in ASI;
Vfe = Flaps Extended speed–> Max speed w/ flaps extended; end of white arc on ASI
What type of gusts are considered during aircraft design?
1- Horizontal gusts of different speeds
2- Vertical gusts of different speeds
3- Gusts of the same speed at different angles
4- None of the answers is correct
Vertical gusts of different speeds
VS1 = Stall speed –> Minimum speed at which aircraft is controllable
Va = Maneuvering speed –> Va = VS1 x (√n); Va < Vc Max speed for control surface full deflection. Depends on mass and pressure altitude.
Vb = Design speed for max gust intensity –> 66ft/s vertical gust. Flying through turbulence at Vb provides max protectiong from damage
Vc = Design cruising speed –> Used to assess strenght requirements in cruise. 50ft/s vertical gust
Vd = Design Dive speed –> Highest speed the aircraft is designed to achieve. 25 ft/s vertical gust
Vra = Speed Rough Air –> recommended turbulence penetration speed
Vne = Never Exceed speed –> <0.9*Vd to enable upset recovery; relevant to small aircraft; marked as red line in ASI;
Vfe = Flaps Extended speed–> Max speed w/ flaps extended; end of white arc on ASI
What is true about the never exceed speed VNE? Select the most complete answer.
1- VNE is relevant for small aircraft
2- VNE is marked as a red line on the airspeed indicator
3- VNE is set below the VD to enable the upset recovery
4- All answers are correct
All answers are correct
VS1 = Stall speed –> Minimum speed at which aircraft is controllable
Va = Maneuvering speed –> Va = VS1 x (√n); Va < Vc Max speed for control surface full deflection. Depends on mass and pressure altitude.
Vb = Design speed for max gust intensity –> 66ft/s vertical gust. Flying through turbulence at Vb provides max protectiong from damage
Vc = Design cruising speed –> Used to assess strenght requirements in cruise. 50ft/s vertical gust
Vd = Design Dive speed –> Highest speed the aircraft is designed to achieve. 25 ft/s vertical gust
Vra = Speed Rough Air –> recommended turbulence penetration speed
Vne = Never Exceed speed –> <0.9*Vd to enable upset recovery; relevant to small aircraft; marked as red line in ASI;
Vfe = Flaps Extended speed–> Max speed w/ flaps extended; end of white arc on ASI
How should be the aircraft designed?
1- To make the natural frequencies occur at speeds beyond VD
2- To make the natural frequencies occur at speeds below VD
3- To make the natural frequencies occur at speeds below VC
4- To make the natural frequencies occur at speeds below VB
To make the natural frequencies occur at speeds beyond VD
What will be the design manoeuvring speed if the VS = 170 kt and n = 2.5?
1- 126 m/s
2- 567 km/h
3- 453 km/h
4- 269 kt
269 kt
n = load factor = Lift / Weight
VS1 = Stall speed –> Minimum speed at which aircraft is controllable
Va = Maneuvering speed –> Va = VS1 x (√n); Va < Vc Max speed for control surface full deflection. Depends on mass and pressure altitude.
Vb = Design speed for max gust intensity –> 66ft/s vertical gust. Flying through turbulence at Vb provides max protectiong from damage
Vc = Design cruising speed –> Used to assess strenght requirements in cruise. 50ft/s vertical gust
Vd = Design Dive speed –> Highest speed the aircraft is designed to achieve. 25 ft/s vertical gust
Vra = Speed Rough Air –> recommended turbulence penetration speed
Vne = Never Exceed speed –> <0.9*Vd to enable upset recovery; relevant to small aircraft; marked as red line in ASI;
Vfe = Flaps Extended speed–> Max speed w/ flaps extended; end of white arc on ASI
What are the benefits of using constant speed propellers? Select the most complete answer.
1- All answers are correct
2- High efficiency can be obtained over a wider range of TAS
3- Improved performance for the take-off
4- Improved performance for the climb
All answers are correct
PROPELLERS:
1) Fixed pitch prop:
-No moving parts
-AoA is set during manufacturing
-RPM depends on engine speed
2) Variable pitch prop:
2.1. Adjustable pitch prop –> on the ground
2.2. Two pitch prop –> 2 settings (fine or coarse pitch)
2.3. Constant speed prop:
-Modern aircraft
-Controlled automatically to keep selected RPM by changing blade angle
-Increase airspeed = same RPM = decrease AoA (fine pitch) = Decrease thrust = Decrease torque
-Decrease airspeed = same RPM = increase AoA (coarse pitch) = increase thrust = increase torque
What will the torque reaction do in the aircraft equipped with a clockwise rotating propeller?
1- None of the answers is correct
2- The torque reaction will make the aircraft roll to the right
3- The torque reaction will make the aircraft roll to the left
4- The torque reaction will make the aircraft yaw to the right
The torque reaction will make the aircraft roll to the left
TORQUE REACTION:
-Propeller rotates clock.wise, so torque reaction will be anti-clockwise
-Greatest torque reaction = T/O + high power setting + Low airspeed
–> during flight aircraft ROLLS TO THE LEFT
–> on the ground aircraft YAWS TO THE LEFT
How is the angle of attack defined?
1- The angle between the blade chord and the relative airflow
2- The angle between the blade chord and the plane of rotation
3- The angle between the actual path of the propeller and the plane of rotation
4- None of the answers is correct
The angle between the blade chord and the relative airflow
AoA:
= Angle between blade chord line and relative airflow
-Depends on RPM + true airspeed
BLADE ANGLE (pitch):
= Angle between blade chord line and plane of rotation
-Decreases from root to tip - blade twist - (this change in blade angle along the blade keeps an uniform AoA)
-Determines the geometric pitch (=distance the prop would move forward in 1 RPM at zero AoA)
When a force directed upwards is applied to the horizontal stabilizer in an aircraft with an anti-clockwise rotating propeller which precession moment occurs?
1- The left yawing moment
2- None of the answers is correct
3- The pitching down moment
4- The pitching up moment
None of the answers is correct
Correct would be: yaw to the right
GYROSCOPIC PRECESSION:
= Force is felt at 90º from applied force
- Induced by PITCH and YAW
- On a clockwise prop:
-Pitch up = yaw to right
-Pitch down = yaw to left
-Yaw to right = pitch up
-Yaw to left = pitch down
Note: Same as car blinkers “up is right, down is left”
P-FACTOR (asymmetric prop blade effect);
= induced by inclination of prop axis to relative airflow
-Highest when full power + low airspeed
-Blade that is going down –> higher AoA –> more thrust
-Blade that is going up –> lower AoA –> less thrust
-Generates LEFT YAW in a nose-up position!
SPIRAL SLIPSTREAM:
= Rotating prop produces airflow that moves backwards around the aircraft ultimately acting on the vertical stabilizer, producing LEFT YAW.
-Depends on throttle and RPM
-reduced by:
-Tab on the rudder
-Engline thrust line slighty deviated to the right
What is the blade twist?
1- The chord line is curved
2- None of the answers is correct
3- The change of the aerofoil along the propeller span
4- The change of the blade angle along the propeller span
The change of the blade angle along the propeller span
AoA:
= Angle between blade chord line and relative airflow
-Depends on RPM + true airspeed
BLADE ANGLE (pitch):
= Angle between blade chord line and plane of rotation
-Decreases from root to tip - blade twist - (this change in blade angle along the blade keeps an uniform AoA)
-Determines the geometric pitch (=distance the prop would move forward in 1 RPM at zero AoA)
