Stability

Question 1

What is a stable aircraft?

Answer 1

Ability to return to a flight condition after a disturbing force has been removed without pilot input.

Question 2

Static stability

Answer 2

Aircraft’s immediate response

Question 3

Dynamic stability

Answer 3

Aircrafts long term response

Question 4

Statically stable meaning

Answer 4

Body returns to equilibrium immediately.

Question 5

Static neutral stability meaning

Answer 5

Body will take up a new equilibrium position

Question 6

Statically unstable

Answer 6

Body diverges from its equilibrium position

Question 7

Active stability meaning

Answer 7

Achieved by automatic operation of flight controls

Question 8

Passive stability meaning

Answer 8

Interaction between airflow and aircraft

Question 9

Longitudinal stability- movement?

Answer 9

Pitch

Question 10

Lateral stability- movement?

Answer 10

Roll

Question 11

Directional stability- movement?

Answer 11

Yaw

Question 12

Device for passive lateral stability?

Answer 12

Dihedral angled wings

Question 13

Difference between short term pitch oscillations and phugoids?

Answer 13

STPOs last around 1 second and don’t change altitude. Phugoids last around 30 seconds and changes altitude.

Question 14

What does a flap type control surface do?

Answer 14

Changes camber of that part of aerofoil

Question 15

What is lift force affected by?

Answer 15

Density of air, velocity of airflow, size and shape of control surface, angle of deflection

Question 16

What is the cause of aileron yaw?

Answer 16

Down aileron increases the drag, the up aileron has a smaller increase.

Question 17

What is a frise aileron

Answer 17

Hinged on upper surface, nose of flap pushed into opposite direction a little bit

Question 18

What is a Differential aileron

Answer 18

Aileron moves up more than down.

Question 19

How do we reduce stick loading

Answer 19

Aerodynamic balance

Question 20

What are the devices used in trimming?

Answer 20

Fixed trim tabs, variable trim tabs or variable incidence tailplanes

Question 21

What is flutter

Answer 21

Rapid undamped oscillations of a control surface

Question 22

How do we overcome flutter?

Answer 22

Mass balancing. Adding weight forward of the hinge line to bring CofG forward.

Question 23

Uses of Spoilers

Answer 23

Lift dump, role control, speed breaks