AA1217 Stability

Question 1

Define positive stability

Answer 1

when disturbed, the tendency to return to the initial position (marble in a bowl)

Question 2

Define negative stability

Answer 2

when disturbed, the tendency to diverge from the initial position (marble on a beach ball)

Question 3

Define neutral stability

Answer 3

when disturbed, the tendency to accept the change and establish a new resting position (marble on a floor)

Question 4

Define static stability

Answer 4

the initial reaction to a disturbance

Question 5

Define dynamic stability

Answer 5

The reaction to a distubance over time

Question 6

What kind of static stability is required to have dynamic stability

Answer 6

positive

Question 7

What will a graph of negative dynamic stabilty look like

Answer 7

oscillations with increasing amplitude

Question 8

List the general aircraft design characteristics which contribute to positve yaw stability

Answer 8

the two main ones are size of the vertical tail and its distance from the vertical axis (CG). Also the wing sweepback and the yaw damper.

Question 9

List the cause and effect of adverse yaw

Answer 9

when deflecting ailerons, the up going wing creates more lift. When creating more lift it also creates more drag. The increased drag pulls the nose towards the up going wing (opposite the direction of the roll)

Question 10

Identify the methods available to counter the effects of adverse yaw

Answer 10

differential ailerons (the down going aileron deflects more than the up going aileron) and rudder into the turn

Question 11

List the general aircraft design characteristics which contribute to positive roll stability

Answer 11

wing position (high wing more stable than low), sweepback wings (more stable than no sweepback), dihedral (more stable than no dihedral)

Question 12

List the general aircraft design characteristics which contribute to positve pitch stability

Answer 12

CG location in relation to the aerodynamic center of forces