8.4 flight stability and dynamics

Question 1

stability in an aircraft affects two areas what are they

Answer 1

menoeuvrability and controllability

Question 2

aircraft principal axes of flight pass through what point

Answer 2

CG centre of gravity

Question 3

motion about the vertical axis is what and controlled by what

Answer 3

Yaw and the rudder

Question 4

a positive yawing motion moves the nose of the aicraft which way

Answer 4

to the right

Question 5

lateral axis is a line drawn from what points

Answer 5

wingtip to wingtip. directed to the right

Question 6

motion about the lateral axis is called what

Answer 6

pitch

Question 7

a positive pitching motion does what to the nose of the aircraft

Answer 7

raises nose and lowers the tail. primarily controlled by the elevators

Question 8

what is the motion about longitudinal axis called

Answer 8

roll.

Question 9

longitudinal axis has a line which does what

Answer 9

directed forward parallel to the fuselage reference point

Question 10

angular displacement about the longitudinal axis is called a what

Answer 10

bank

Question 11

a positive rolling motion lifts which wing

Answer 11

left wing and lowers the right wing.

Question 12

what are the primary and secondary controls on a bank

Answer 12

primary = ailerons
secondary effect = rudder

Question 13

what is the axis of stability for yaw

Answer 13

directional

Question 14

what is the axis of stability for pitch

Answer 14

longitudinal

Question 15

what is the axis of stability for roll

Answer 15

lateral

Question 16

what does static stability mean

Answer 16

aircrafts initial tendency to return back to a position of equilibrium

Question 17

what are the three kinds of static stability

Answer 17

positive static stability
neutral static stability
negative static stability

Question 18

positive static stability is

Answer 18

tendency to return to original state of equilibrium.

Question 19

neutral static stability is

Answer 19

tends to stay in its new attitude when its disturbed. eg. if turbulence pitches nose up 5 degrees it will stay at 5 degrees nose up

Question 20

negative static stability is

Answer 20

continues moving away from its original attitude when its disturbed. e.g if turbulence pitches nose up it continues pitching up. very undesirable situation.

Question 21

what is dynamic stability

Answer 21

aircraft response over time when disturbed from pitch, yaw, bank.

Question 22

the three types of dynamic stability are

Answer 22

positive dynamic stability
neutral dynamic stability
negative dynamic stability

Question 23

positive dynamic stability is where aircraft has

Answer 23

oscillations that dampen out over time and because it is positive, it returns toward its equilibrium state

Question 24

neutral dynamic stability is where aircraft has

Answer 24

oscillations that never dampen out.

Question 25

negative dynamic stability is where the aircraft has

Answer 25

oscillations that get worse over time

Question 26

static longitudinal stability, or instability in an aircraft depends on what three factors

Answer 26

-location of wing in respect to CG
-location of horizontal tail surfaces in respect to CG
-area or size of tail surfaces

Question 27

if the distance between the cg and aerodynamic centre is great..

Answer 27

then the longitudinal stability is high. if distance is small stability is low.

Question 28

the directional or “weathercock” stability depends on what

Answer 28

the fin aka vertical stab and the sweepback of the wing

Question 29

some aircraft increase the surface area behind the cg to improve what type of stability

Answer 29

directional by methods such as a dorsal fin, keel surface.

Question 30

what are the four main factors that make aircraft laterally stable

Answer 30

dihedral
sweep-back
keel effect
weight distribution

Question 31

what reduces sideslip

Answer 31

dihedral angle

Question 32

what is sideslip angle

Answer 32

it is the angle between the aircraft centreline and the sideslip direction

Question 33

high wing aircraft have a lesser or greater keel effect than low wing aircraft

Answer 33

greater

Question 34

the keel effect is

Answer 34

in a sideslip, the fuselage provides a broad area upon which the relative wind strikes, forcing the fuselage to become parallel to the wind.

Question 35

if one axis or stability is stronger than the other what could happen

Answer 35

spiral dive or dutch roll

Question 36

spiral dive is when there is a greater effect on

Answer 36

the directional stability than on the lateral stability

Question 37

dutch roll exists when there is a greater effect on the

Answer 37

lateral stability than on the directional stability . lateral-directional oscillation

Question 38

dutch roll can be partially overcome by

Answer 38

reducing sweep angle and improving directional stability

Question 39

directional stability can be improved by

Answer 39

increasing size of vertical stab but this has weight and drag drawbacks

Question 40

aircraft which have neutral or negative stability is aka

Answer 40

relaxed stability

Question 41

relaxed stability allows aircraft to be designed for purely

Answer 41

aerodynamic efficiency opposed to handling or ‘‘flyability”

Question 42

stability increases as speed increases true or false

Answer 42

true