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PPL - PoF > Equilibrium, Stalling & Spinning > Flashcards

Equilibrium, Stalling & Spinning Flashcards

1
Q

What are the 4 forces in flight

A

Lift
Weight
Thrust
Drag

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2
Q

In un-accelerated level flight;
LIFT equals ??
THRUST equals ??

A

LIFT equals WEIGHT
THRUST equals DRAG

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3
Q

In what direction does lift force act in relation to the aerofoil

A

Perpendicular

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4
Q

How does weight act in relation to the earth

A

Always acts straight down

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5
Q

If an aircraft is banked, what can a pilot normally do to ensure the perpendicular component of lift equals weight

A

Increase the AoA

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6
Q

What component of lift produces a turning force which “pulls” the aircraft nose in the direction of the bank angle

A

Horizontal Component

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7
Q

If an aircraft is climbing with level wings at a given rate of climb and a bank is introduced, what will happen to the rate of climb

A

DECREASES / REDUCED
Lift no longer equals weight as lift acts perpendicular to the aerofoil, which is now banked.
Another component must compensate i.e. increased AoA or increased thrust

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8
Q

What force acts opposite and equal to the horizontal component of lift

A

Centrifugal force

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9
Q

The resultant force of Centrifugal force and weight is known as what

A

G load

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10
Q

What happens to G load as bank angle is increased

A

Load Increases

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11
Q

In a steady climb, weight is supported by what

A

Lift and a component of thrust

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12
Q

As AoA increases, the Center of Lift moves FORWARDS or AFT of the leading edge

A

FORWARD

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13
Q

As AoA increases, airflow separation beings to occur at the LEADING EDGE or TRAILING EDGE

A

TRAILING EDGE

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14
Q

Once airflow separation has begun, as AoA increases, separation moves FORWARD or AFT of the leading edge

A

FORWARD

Airflow separation begins to occur on the upper surface trailing edge, moving forward along the upper surface towards the leading edge ias AoA increases further

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15
Q

What must happen to recover from a stall

A

AoA MUST be reduced

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16
Q

For a given clearn aerofoil

Stall occurs at the same AoA irrespective of what

A

Weight and Speed

The stall for a given clean aerofoil always occurs at the same AoA irrespective of weight and airspeed

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17
Q

3 basic factors that can influence the stall

A

Ground Effect
Aerofoil shape
Propeller Slipstream

18
Q

Contaminated aerofoils will INCREASE or DECREASE the stall speed

A

INCREASED

INCREASED meaning the onset of stall will happen faster at a given airspeed
i.e. 100 kts airspeed, stall WAS 50 kts, NOW 80 kts

19
Q

Propeller slipstream can do what to boundary layer separation

A

DELAY

Low speed/High power may result in lower stalling speed

20
Q

What effect does tailplane downforce have

A

Increased effect to TOTAL WEIGHT

21
Q

What is required if there is an increase in tailplane downforce

A

INCREASED LIFT

22
Q

For a given velocity

What happens to stall speed if CoG is moved forward

A

INCREASES

Forward CoG creates a pitch down tendency
CoG is forward of the CoL (Center of Lift)
Nose down tendency requires MORE tailplane downforce
More downforce = increase in total weight
For a given speed, only way to maintain lift when weight increased is increase AoA
Increased AoA brings it closer to Acrit, meaning it will be reached sooner

23
Q

For a given velocity

What happens to stall speed if wing load is reduced (aircraft weights less)

A

REDUCED

Less load (weight) requires less lift, meaning a reduced AoA for a given airspeed

24
Q

For a given load

What happens to stall speed if more thrust power is used

A

REDUCED

Thrust includes a vertical vector.
More thrust increases velocity
If velocity increases, overall lift will increase
To maintain steady flight with increase velocity, Less AoA is required to provide lift

25
Q

Assuming no more power available

Why does altitude effect a stall

A

Increased altitude means less air density and pressure

To maintain lift where there is less density and no more speed available, AoA must be increased

26
Q

An increased bank angle results in HIGHER or LOWER stall speed

A

HIGHER

To maintain lift in a bank, AoA is increased. To overcome increased drag from increased AoA, more thrust is applied

27
Q

What is the formula for the new stall speed with an increase in load factor

A

New Vs = Old Vs x √ Load Factor

28
Q

What is the formula for wingloading

A

wingloading (n) = Aircraft weight / wing area

29
Q

What is the formula for load factor

A

load factor = lift / weight

30
Q

What is the formula for determining stall speed in a turn

A

Vs (turn) = Vs1 √ 1 / cosӨ

Vs (turn) is what we want to determine
Vs1 is stall speed in straight and level flight
Wing loading in a turn is 1 / cos (angle of bank)

31
Q

What is a dynamic stall

A

Stall occuring at a higher critical AoA at which aerofoil normally stalls

Example; sudden vertical upwards gust significantly increases the AoA to the RAF

32
Q

What % are approach speeds factored by of the landing configuration stall speed

A

30%

33
Q

A stall speed in landing configuration is 35 kts. What is the approach speed

A

45.5 kts
Approach speed factored by 30% of landing configuration stall speed
35 x 1.3 = 45.5 kts

34
Q

At what margin above the stall speed are stall warners typically designed to operate at

A

4 kt to 12 kt

35
Q

What 2 elements must be present for a spin

A

Spin = Stall + Yaw

36
Q

In a spin, which wing is more stalled and creates more drag

A

Down-going wing
Has a higher AoA

Outside wing is travelling faster in the turn

37
Q

What are the 3 stages of spin stalling

A

Incipient Stage
Fully Developed Spin
Spin Recovery

38
Q

What are the stages to recover from a spin

A

Power to idle
Centralise flying controls
Full OPPOSITE rudder
Control column forward
Once spinning stops, centralise controls
Recover from dive (pull back gently)
Reset power

39
Q

When Acrit is exceeded, what happens to the Coefficient of Lift

A

DECREASES

Once wing is stalled, there is significant loss of lift

40
Q

Stalling speed (IAS) is dependent upon which 4 factors

A
  1. Weight of aircraft
  2. Center of Gravity
  3. Load Factor
  4. Power Setting

If aircraft weights more, stall speed increases as more AoA needed to create same lift
If centre of gravity is forward, more downforce required to keep straight and level. More downforce = more weight = more lift through increase AoA
More load = more weight to lift. Means more AoA needed to increase lift. Increased AoA means increase of stall speed
Less power means less airspeed. Less airspeed needs more AoA to maintain lift.

PPL - PoF (9 decks)

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