Chapter 21 - Stability

Question 1

Increased stability does what to controllability

Answer 1

decreases

Question 2

What are used to overcome the A/C stability

Answer 2

Control inputs

Question 3

What is required to stay in equilibrium when out of trim

Answer 3

Control surface input

Question 4

Static Stability is the

Answer 4

initial motion

Question 5

Dynamic Stability is the

Answer 5

Subsequence motion

Question 6

Positively stable =

Answer 6

tendency to return original position

Question 7

Neutral stable =

Answer 7

No tendency to move

Question 8

Negatively stable =

Answer 8

Tendency to diverge away

Question 9

If it take less time to get to half amplitude what is the stability

Answer 9

increased positive dynamic stability

Question 10

Aerodynamic Centre is

Answer 10

The point at which all AOA stay constant and all pitching moments happen round. (don’t use CofP as it always moving)

Question 11

Give the AC on the chord for the following
Symmetrical
Cambered
High Speed

Answer 11

25%
23-27%
50%

Question 12

Rolling Coefficient is

Answer 12

L’ CL’

Question 13

Yaw Coefficient is

Answer 13

N CN

Question 14

Pitching Coefficient is

Answer 14

M CM

Question 15

Longitudinal Static stability is attained with

Answer 15

Tail plane, distance of the tailplane from the CG

Question 16

A forward CofG does what to stability

Answer 16

More stable

Question 17

Directional Static stability is attained with

Answer 17

Vertical stabiliser, fwd CofG, Amount of fuselage behind CofG

Question 18

Lateral Static stability - which is the main contributor

Answer 18

Wing

Question 19

x 4 Lateral wing stability devices

Answer 19

Dihedral
swept back
High mounted wings
High Keel surface

Question 20

Absolute angle of attack is

Answer 20

The absolute angle of attack uses zero lift line and RAF

Question 21

Dorsal + Ventral fins do what to stability, because they are where

Answer 21

Dorsal increases
Ventral decreases
In the keel area above and below the CofG

Question 22

Stick fixed position means

Answer 22

Pilot or auto pilot is holding control

Question 23

Stick free means

Answer 23

No force acting on the control column

Question 24

If a gust of air pitches the nose up in a stick free condition what happens and stability is

Answer 24

The elevator lags behind the stab with pitch up aerodynamic force causes the a/c to pitch up more

unstable

Question 25

stick free is less stable than stick fixed

Answer 25

yes