RPL Aerodynamics 2 Flashcards
What does “straight” and “level” mean?
Straight - maintain a constant heading
Level - to maintain constant altitude
Which requires to be constant to remain straight and levelled?
Altitude
Airspeed
Heading
Balance
What are the factors affecting weight?
Speed
Weight
Flaps
Power
What is lift proportional to?
Angle of attack and velocity
What is the most efficient angle of attack?
4 Degrees
What is the critical angle?
16 Degrees
If there is a change to a single force, how can equilibrium be achieved again?
Equalising the change of force with its opposite force
What does weight equal to in level flight?
Weight = Lift
If weight is reduced in level flight, what must be done to overcome the reduction in weight?
Reduction in lift
What must be done to decrease magnitude of lift?
Angle of attack must be decreased for a given airspeed
What is required to be done to prevent acceleration once angle of attack is reduced?
Thrust will need to be reduced in order to counteract a decrease in induced drag that can result in acceleration
What are the effects of increasing power?
Nose pitch up
Increase in speed
Increased Lift
What is the effect of decreasing power?
Nose pitches down
If the propellor spins in a clockwise direction whilst a power increase, what are the effects?
Nose pitches up followed by a roll and yaw to the left?
How does a decrease in power affect an aircraft if the propellor is rotating clockwise?
Nose pitches down
What is steady state climb?
Aircraft where aircraft is climbing at a constant speed while maintaining constant heading and constant rate of climb
How does thrust change in a climb?
Thrust in a climb adds a vertical aspect via the increased angle of attack
Why must thrust be increased in a climb?
Thrust must be increased in order to counteract weight + rearward component of weight
What is the rearward component of weight?
The rearward component of weight is the additional force applied in a climb in which is the force of gravity and weight
What are the 3 different types of climbs and what are their abbreviations?
Best angle of climb (Vx)
Best rate of climb (Vy)
Cruise Climb (Vcc)
What is the angle of climb and rate of climb?
Angle of climb - flight path during a climb and the horizontal ground
Rate of climb - Amount of altitude gained within a certain time frame
What is the best angle of climb?
(Vx)
Aims to achieve maximum height in a minimal horizontal distance in which is primarily used for obstacle distance
What are the effects of a best angle of climb?
Poor engine cooling and low forward visibility
Provides maximum excess thrust above straight and level flight
What airspeed provides the best angle fora best angle of climb?
63kts
What is the best rate of climb?
(Vy)
Aims to achieve maximum height gained in minimum time in which is the most commonly used type of climb
What are the effects of a best rate of climb?
Increased engine cooling, visibility and groundspeed improved
Provides a maximum excess power
What is the airspeed to achieve a best rate of climb?
79kts
What is a cruise climb?
(Vcc)
Cruise climb is the compromise between best rate and a increased groundspeed
What are the benefits of cruise climb?
Improved visibility
Better engine cooling
Better passenger comfort
Get to destination in the shortest time
What are the factors affecting climb performance?
Power Height Weight Flap Wind
How does altitude and temperature affect climb?
Increasing altitude decreases air density in which climb performance reduces
More power output is required
Power output is reduced with increase altitude
What are the worst performance conditions?
Hot temperature at High altitude
What are the effects of reduced density?
Reduced aerodynamic lift and engine performance
What is the absolute ceiling?
The altitude in which it is impossible to climb further
What are the effects of weight in a climb?
Nose is to be pitched down to maintain climb speed in which climb performance reduces
RoC is reduced
AoC is reduced
How does flap affect climb?
Further stages of flap create more drag in which decreases rate of climb and angle of climb
Reduces amount of excess thrust available
How does wind affect climb?
Angle of climb affected depending on direction of wind
How does a headwind and a tailwind affect climb?
Headwind - increased angle of climb
Tailwind - decreased angle of climb
How is rate of climb affected by wind?
Rate of climb is not affected by a steady wind
Why is rate of climb not affected by wind?
Rate of climb is a measure of climb within a given time frame
What are the 3 types of descents?
Glide descent
Cruise descent
Approach descent
What is the angle of descent and rate of descent?
Angle of descent - Angle between the aircrafts flight path and horizontal ground
Rate of descent - amount of altitude lost within a certain time frame
What is the additional weight of a glide descent?
Forward component of weight
What is the forward component of weight?
The force in which is affected by weight and gravity in combination with the direction of thrust
What are the difference in forces within a glide descent?
Lift < Weight
Thrust < Drag
FCW = Drag
How does power affect angle of descent?
Increasing power and raising the nose to maintain airspeed and result in a shallower descent
Decreasing power and lowering the nose to maintain airspeed will result in a steeper descent
How is glide angle determined?
By utilising the best Lift/Drag ratio in which is performed by setting an AoA that gives a certain speed
How can the best Lift/Drag ratio be affected?
Best L/D ratio is affected by weight in which increased/decreased weight influences the required lift so airspeed is required to be manipulated to maintain the same L/D ratio
How does heavier aircraft compare to lighter aircraft in a descent?
Heavier aircrafts have higher airspeed in which it will reach the ground faster before a lighter aircraft
(AoD is the same but RoD decreases for lighter aircraft)
How does airspeed affect descent?
Too much or too little airspeed could miss or overshoot the landing target
Why can’t speed be changed on a glide via power and what is an alternative to getting speed from power?
Power cannot be utilised in a glide due to a present engine failure or simulation of engine failure. Speed can then be manipulated by adjusting attitude and AoA
What are the effects of flaps on a descent?
Extension of flaps increase both lift and drag in which spoils the best L/D ratio and degrades gliding performance (AoD/RoD decreases)
How does a headwind affect descent?
Headwind will increase the AoD as the wind pushes against the motion of aircraft’s thrust and will not reduce RoD
How does tailwind affect descent?
Tailwind will decrease AoD as wind pushes in the direction of the aircraft’s motion and will not reduce RoD
What is turning?
An aircraft’s change in direction via the banking of an aircraft’s wings to roll
What is required in order to maintain the vertical component of lift during a turn?
Increased AoA and Airspeed
What are the load factors in a 45, 60 and 75 degree turns?
45 - 1.4gs
60 - 2gs
75 - 4gs
What are the angle of banks for a gentle, medium and steep turn?
Gentle - 0-20 degrees
Medium 21-44 degrees
Steep - 45+
What is the max AoB on a levelled turn?
30 Degrees
What happens to the outer wing on a climbing turn?
Travels a greater distance than inner wing and also has a greater AoA than inner wing
What is the turn on conditions on a climbing turn?
Max AoB of 15 degrees and full power
What happens to the inner wing on a descending turn?
Travels faster and has a greater AoA compared to outside wing
What is the max AoB of a descending turn?
30 Degrees
What is a rate 1 turn?
360 Degrees in 2 Minutes
What is a rate of turn?
Time taken to complete a 360 degree turn
What is the formula of a Rate 1 Turn?
AoB = (TAS/10 + 7)
How would a pilot achieve the smallest turn radius?
Slowest speed with maximum possible bank
How does an increased IAS affect performance?
Increased radius of turn and decreased rate of turn
How does a decrease in IAS affect performance?
Decreased radius of turn and increased rate of turn
How does an increase of AoB affect performance?
Decreased radius of turn and increased rate of turn
How does an increase in AoB affect performance?
Increased radius of turn and decreased rate of turn
How does increased airspeed affect turn performance?
Increased radius of turn and decreased rate of turn
How does decreased airspeed affect turn performance?
Decreased radius of turn and increased rate of turn
What is adverse yaw?
Adverse yaw is the aircraft yawing in the opposite direction of the turn due to the increasing drag from the uplifted wing
How is adverse yaw counteracted?
Application of rudder in the direction of turn
What is a stall?
When aircraft passes the critical angle and lift decreases
Does a stall have anything to do with the engine?
No
How is angle of attack measured in straight and levelled flight?
Airspeed
Is there an instrument to indicate AoA?
No
Is stall speed consistent?
No as it varies depending on different aircraft configurations
What are the factors affecting stall speed?
Weight Flaps Power Wind condition Load Factor
How does weight affect stall speed?
More weight increases stall speed
How does flaps affect stall speed
Greater stages of flap extension decreases stall speed
How does greater power affect stall speed?
Greater power increases stall speed
How does increased load factor affect stall speed?
Increases stall speed
What are the symptoms of a basic stall?
Control column in back position High nose attitude Low airspeed Less effective control Stall warning Possible control buffet
What happens during a stall?
Nose lowers
Loss of height
Possible wing drop
What is a incipient spin?
A period following a stall in which wing drop is present
How to recover from an incipient spin?
Reduce power to idle Forward pressure on control column Neutral ailerons Apply full rudder to opposite direction of rotation Release rudder when rotation stops
When wings un-stalled Level wings with aileron Raise nose to climb altitude Full power Carburetor heat off Climb at (Vy) After take-off checks
What is a washout?
A twist of a wing that helps to prevent wing drop via reducing angle of attack at the wing tip
What is a stall strip?
A small triangular strip that encourages stall at the wing root before wing tip via producing turbulent airflow near the critical angle
