ADY - Stalls, Spins and Stability Flashcards Preview

CPL Aerodynamics > ADY - Stalls, Spins and Stability > Flashcards

Flashcards in ADY - Stalls, Spins and Stability Deck (54)
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1
Q

What type of stall occurs when you are pulling out of a dive at high IAS

A

Dynamic or high speed stall

2
Q

The definition of a stall is …..

A

That condition where an increase in AoA results in less lift

3
Q

The downward component of the vortex at the wing tip causes what to happen ……

A

this causes the AoA at the wing tip to be less than at the wing root so the wing root will stall before the wing tip causing a much less pronounced wing drop

4
Q

What type of aircraft are subject to dynamic stalls …..

A

Aircraft with high wing loading

5
Q

Name 3 design features to minimise the stall …..

A
  1. Wash out
  2. Stall strips
  3. Elevator stops
6
Q

The published stall speed in an aircraft’s flight manual is meant for …..

A

Usually the max all up weight when the aircraft is in level flight only

7
Q

Name 3 factors that decrease the stalling IAS …..

A
  1. Flaps - Increase CL
  2. Power - has a component of lift to it
  3. CoG position - Moving aft is like reducing weight
8
Q

Name 3 factors that increase the stall IAS …..

A
  1. Weight - more weight increases the stall speed
  2. Load factor - Is the same as a weight increase
  3. Ice or damage - Change the shape of the aerofoil and hence its lifting properties
9
Q

It is impossible to enter a spin unless …..

A

the wings have stalled

10
Q

In a spin the downward going wing moves …..

A

downwards and backwards

11
Q

The rotation in a spin continues …..

A

while ever the wings are stalled

12
Q

What happens to the rate of rotation once a spin has developed …..

A

it becomes constant

13
Q

During a spin the balance ball will …..

A

Deflect away from the direction of the spin

14
Q

During a spin the ASI will ……

A

give a very low and unchanging reading which is meaningless

15
Q

Spin recovery requires you to do ……

A
  1. Unstall the wings
  2. stop the rotation with opposite rudder

The sequence and method is aircraft type dependant

16
Q

Define Stability …..

A

Stability is the property possessed by an object which causes it to seek to return to its original position after it has been displaced

17
Q

Dynamic stability - the object ….. .. ….. after a disturbance

A

returns to rest

18
Q

Dynamic instability - the object makes no attempt to ….. .. …..

A

return to rest

19
Q

Neutral stability - After a disturbance there is no further attempt to …..

A

diverge further from or return to rest

20
Q

Longitudinal stability is in the …… area of motion

A

pitching

21
Q

….. is the most important variable in controlling longituinal stability

A

CoG

22
Q

When the CoG is ….. this has a ….. effect.

This effect is proportional to the …..

A

aft, destabalizing, arm from the CoG to the CoP

23
Q

The ….. from the CoG to the ….. in the ….. ….. is a major influincing factor in longitudinal stability

A

distance of the arm, Cop, tailplane

24
Q

3 design features that assist longitudinal stability are:

A
  1. Tailplane volume
  2. Orientation of the lift and weight
  3. Longitudinal dihedral
25
Q

Longitudinal Dihedral: sometimes the taleplane has a smaller ….. .. …..

A

angle of incidence

26
Q

The effectiveness of the tailplane depends on 2 things …..

A
  1. The distance from the CoG
  2. The area of the tailplane
27
Q

Lateral stability is in which plane of motion?

A

roll

28
Q

lateral stability and dihedral:

Describe how dihedral assist in lateral stability …..

A

In a side slip the AoA is greater on the lower wing. When there is dihedral on the wing this AoA is minimised picking up the wing providing better stability

29
Q

Lateral stability:

Side slip results as the ….. component of the ….. lift vector in a roll

A

horizontal, inclined

30
Q

Lateral stability:

Keel surfaces below the roll axis cause …..

A

lateral instability

31
Q

Lateral stability:

Keel surfaces above the roll axis provide …..

A

Improved stability

32
Q

In order to maintain manoeuverability in roll, lateral stability is usually …..

A

weak

33
Q

The more stable an aeroplane is in lateral stability the …..

A

less manoeuvarable it will be

34
Q

In a side slip on a swept back wing what happens to the lower wing …..

A
  1. The effective span is greatly increased
  2. The effective cord is reduced
  3. Much more air flows across the lower wing
35
Q

What is anhedral …..

A

It is negative dihedral where the wings are set down and below the yawing plane. This takes away some of the excessive lateral stability to improve manoeuvrability

36
Q

Define directional stability …..

A

the property that causes the aircraft to align its longitudinal axis with the direction of the relative airflow

Simply put - the property seeks to point the nose of the aeroplane into the wind

37
Q

Relative airflow striking the surfaces forward of the CoG cause …..

A

Directional instability

38
Q

Relative airflow striking the surfaces aft of the CoG …..

A

Create directional stability

39
Q

What is the major contributor to directional stability …..

A

the surface area of the fin and rudder

40
Q

Lateral stability is always ….. than directional stability

A

weaker

41
Q

After a wing drop and no corrective action by the pilot, strong directional stability dominates providing a ….. into the direction of the sideslip potentially initiating a …..

A

yaw, spiral dive

42
Q

A spiral dive is a …..

A

dynamically unstable condition where the nose is low and the airspeed is increasing

43
Q

2 likely causes of a spiral dive are …..

A
  1. pilot incapacitation
  2. Non-IFR training
44
Q

To correct a spiral dive …..

A
  1. Level the wings
  2. Pull up
45
Q

What type of loads are present in a spiral dive …..

A
  1. Tortional
  2. Shearing
46
Q

The primary reason for designing a wing with washout is …..

A

to ensure that the wing root stalls before the wing tip.

This happens as there is less AoA at the wing tip because of the washout

47
Q

The dihedral on a high wing aircraft is usually less than that on a low wing design because the hgh wing design has a …..

A

stronger lateral stability.

remember that the wings are above the weight (lift above weight) so they are naturally more stable laterally

48
Q

If no control inputs are made by the pilot, an aircraft which has rolled to the left from the level attitude will have a natural tendancy to ….

A

yaw to the left

remember after the roll the aircraft sideslips - this is yaw

49
Q

spiral instability is the result of an interaction of …..

A

roll and yaw

50
Q

this combination of stability (or not) would cause a spiral dive …

A

weak lateral and strong directional

51
Q

Longitudinal dihedral enhances stability in pitch by providing an angle of incidence on the tail plane which is …..

A

less than that of the main wings

52
Q

Compared with the upper wing, the lower wing of an aircraft in a spin is experiencing …..

A

more drag and less lift

53
Q

A device which encourages the airflow to seperate from a wing surgace during the stall progression is a …..

A

stall strip

54
Q

The primary reason for designing a wing with anhedral is …..

A

to reduce the leteral stability