ADY - Stalls, Spins and Stability

Question 1

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

Answer 1

Dynamic or high speed stall

Question 2

The definition of a stall is …..

Answer 2

That condition where an increase in AoA results in less lift

Question 3

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

Answer 3

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

Question 4

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

Answer 4

Aircraft with high wing loading

Question 5

Name 3 design features to minimise the stall …..

Answer 5

1. Wash out
2. Stall strips
3. Elevator stops

Question 6

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

Answer 6

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

Question 7

Name 3 factors that decrease the stalling IAS …..

Answer 7

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

Question 8

Name 3 factors that increase the stall IAS …..

Answer 8

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

Question 9

It is impossible to enter a spin unless …..

Answer 9

the wings have stalled

Question 10

In a spin the downward going wing moves …..

Answer 10

downwards and backwards

Question 11

The rotation in a spin continues …..

Answer 11

while ever the wings are stalled

Question 12

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

Answer 12

it becomes constant

Question 13

During a spin the balance ball will …..

Answer 13

Deflect away from the direction of the spin

Question 14

During a spin the ASI will ……

Answer 14

give a very low and unchanging reading which is meaningless

Question 15

Spin recovery requires you to do ……

Answer 15

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

The sequence and method is aircraft type dependant

Question 16

Define Stability …..

Answer 16

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

Question 17

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

Answer 17

returns to rest

Question 18

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

Answer 18

return to rest

Question 19

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

Answer 19

diverge further from or return to rest

Question 20

Longitudinal stability is in the …… area of motion

Answer 20

pitching

Question 21

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

Answer 21

CoG

Question 22

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

This effect is proportional to the …..

Answer 22

aft, destabalizing, arm from the CoG to the CoP

Question 23

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

Answer 23

distance of the arm, Cop, tailplane

Question 24

3 design features that assist longitudinal stability are:

Answer 24

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

Question 25

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

Answer 25

angle of incidence

Question 26

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

Answer 26

1. The distance from the CoG 2. The area of the tailplane

Question 27

Lateral stability is in which plane of motion?

Answer 27

roll

Question 28

lateral stability and dihedral: Describe how dihedral assist in lateral stability .....

Answer 28

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

Question 29

Lateral stability: Side slip results as the ..... component of the ..... lift vector in a roll

Answer 29

horizontal, inclined

Question 30

Lateral stability: Keel surfaces below the roll axis cause .....

Answer 30

lateral instability

Question 31

Lateral stability: Keel surfaces above the roll axis provide .....

Answer 31

Improved stability

Question 32

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

Answer 32

weak

Question 33

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

Answer 33

less manoeuvarable it will be

Question 34

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

Answer 34

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

Question 35

What is anhedral .....

Answer 35

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

Question 36

Define directional stability .....

Answer 36

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

Question 37

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

Answer 37

Directional instability

Question 38

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

Answer 38

Create directional stability

Question 39

What is the major contributor to directional stability .....

Answer 39

the surface area of the fin and rudder

Question 40

Lateral stability is always ..... than directional stability

Answer 40

weaker

Question 41

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 .....

Answer 41

yaw, spiral dive

Question 42

A spiral dive is a .....

Answer 42

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

Question 43

2 likely causes of a spiral dive are .....

Answer 43

1. pilot incapacitation 2. Non-IFR training

Question 44

To correct a spiral dive .....

Answer 44

1. Level the wings 2. Pull up

Question 45

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

Answer 45

1. Tortional 2. Shearing

Question 46

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

Answer 46

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

Question 47

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

Answer 47

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

Question 48

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 ....

Answer 48

yaw to the left remember after the roll the aircraft sideslips - this is yaw

Question 49

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

Answer 49

roll and yaw

Question 50

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

Answer 50

weak lateral and strong directional

Question 51

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

Answer 51

less than that of the main wings

Question 52

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

Answer 52

more drag and less lift

Question 53

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

Answer 53

stall strip

Question 54

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

Answer 54

to reduce the leteral stability