M8.4

Question 1

What are the two types of stability?

Answer 1

• static stability

- dynamic stability

Question 2

What is positive static stability?

Answer 2

When the object returns to its position of equilibrium

Question 3

What is negative static stability?

Answer 3

When the object moves away from its position of equilibrium

Question 4

What is a neutral static stability?

Answer 4

When the object shows no tendency to to move back to its position of equilibrium

Question 5

What must you have to get dynamic stability?

Answer 5

Positive static stability

Question 6

What is dynamic stability?

Answer 6

The continuous motion of a body varies over time

Question 7

What is undamped oscillation?

Answer 7

When something oscillates forever after the initial displacement

Question 8

What is positive dynamic stability?

Answer 8

When the objects stops oscillating over time

Question 9

What is positive dynamic stability also know as?

Answer 9

Dynamically stable

Question 10

What is negative dynamic stability?

Answer 10

When the object will increase oscillating over time

Question 11

What is negative dynamic stability also known as?

Answer 11

Dynamically unstable

Question 12

How do you get neutral static stability (undamped)?

Answer 12

By having the pivot point and centre of gravity in the same place

Question 13

How do you get a negative static stability (divergent)?

Answer 13

By having the pivot point below the centre of gravity

Question 14

How do you get a positive static stability (damped)?

Answer 14

By having the pivot point above the centre of gravity

Question 15

What are the three aircraft axes?

Answer 15

• longitudinal
• vertical
• lateral

Question 16

What does the lateral axis control?

Answer 16

The longitudinal stability (pitch movement)

Question 17

What does the longitudinal axis control?

Answer 17

The lateral stability (roll movement)

Question 18

What does the vertical axis control?

Answer 18

The directional stability (yaw movement)

Question 19

What is another way of saying directional stability?

Answer 19

Weathercock stability

Question 20

What is a dorsal fin?

Answer 20

A fin connecting the vertical stabiliser to the fuselage

Question 21

What is a keel surface

Answer 21

A fin sticking out of the empennage

Question 22

What is the job of a dorsal fin and keel surface?

Answer 22

To increase the side forces to produce positive directional stability

Question 23

How do swept back wings help improve directional stability?

Answer 23

Because if the aircraft starts going off course the forward wing gains higher drag than the other

Question 24

What mainly determines the lateral stability?

Answer 24

• angle of attack
• dihedral
• wing layout

Question 25

What is side-slip angle?

Answer 25

The angle between the aircraft centreline and the side-slip direction

Question 26

What is side slip direction opposite to?

Answer 26

Relative wind

Question 27

The complex interaction of the rolling moment and the yawing moment produces what two types of reaction?

Answer 27

Spiral dive and the Dutch roll

Question 28

When does a spiral dive take place?

Answer 28

When there’s a greater effect on the directional stability than the lateral stability

Question 29

What is a Dutch roll?

Answer 29

A lateral-directional oscillation

Question 30

When does a Dutch roll take place?

Answer 30

When there is a greater effect on the lateral stability than on the directional stability

Question 31

What type of wing is Dutch roll always found on?

Answer 31

Swept wings