Basic Aerodynamic Theory

Question 1

what is static pressure?

Answer 1

static pressure is the prevailing pressure at any given point in the atmosphere

Question 2

when there is no movement between a body and the air around it, pressure on the body is experienced (equally/unevenly)

Answer 2

equally

Question 3

what is dynamic pressure?

Answer 3

the extra pressure generated by virtue of movement between a body and the air around it

Question 4

when there is movement between a body and the surrounding air, the distribution of pressure around the body is (equal/uneven)

Answer 4

uneven

Question 5

what is the equation for total (or pitot) pressure?

Answer 5

pitot pressure = static pressure + dynamic pressure

Question 6

what is indicated airspeed (IAS)? is it corrected for anything?

Answer 6

indicated airspeed (IAS) is the reading on the airspeed indicator. no - instrument errors are so small they can generally be ignored

Question 7

what is calibrated airspeed (CAS)? what is it corrected for?

Answer 7

calibrated airspeed (CAS) is IAS corrected for pressure (or position) error

Question 8

what is equivalent airspeed (EAS)? what is it corrected for?

Answer 8

equivalent airspeed (EAS) is CAS corrected for compressibility error

Question 9

what is true airspeed (TAS)? what is it corrected for?

Answer 9

true airspeed (TAS) is EAS corrected for density error - this fan be calculated using a nav computer

Question 10

what is an aerodynamic force?

Answer 10

an aerodynamic force is a force generated if a solid body is placed in a moving airstream - it originates from the pressure distribution around the body

Question 11

lifting capacity of large, relatively flat bodies is highest when it is (angled slightly/parallel) to the incoming airflow

Answer 11

angled slightly

Question 12

what is an aerofoil?

Answer 12

a tear drop shaped surfaced designed to generate useful aerodynamic force

Question 13

what is the camber of an aerofoil?

Answer 13

camber is the overall curvature of an aerofoil - refer to line of mean camber on the aerofoil diagram

Question 14

high speed aerofoils are generally what shape?

Answer 14

long and thin

Question 15

high lift aerofoils are generally what shape?

Answer 15

shorter and wider compared to high speed aerofoils

Question 16

general purpose (GP) aerofoils are generally what shape?

Answer 16

a combination of high speed and high lift - medium length and width

Question 17

whats the chord line of an aerofoil?

Answer 17

the straight line joining the leading and trailing edges

Question 18

whats the leading edge of an aerofoil?

Answer 18

the edge facing the incoming airstream

Question 19

whats the trailing edge of an aerofoil?

Answer 19

the edge facing the downstream end of the airflow - generally pointed to encourage reconnection of the airstreams

Question 20

whats the chord of an aerofoil?

Answer 20

the distance between the leading and trailing edges, measured along the chord line

Question 21

whats the angle of attack (AoA)?

Answer 21

the angle between the chord line and the incoming relative airflow

Question 22

a higher AoA generally means a (higher/lower) amount of lift

Answer 22

higher, until the critical angle

Question 23

whats the maximum thickness of an aerofoil?

Answer 23

the widest part of an aerofoil

Question 24

how is lift generated?

Answer 24

a combination of bernoullis theorem and newtons third law - airflow remains at a constant while moving around an aerofoil, creating a pressure differential between above and below, and an upward force is created by the downward deflection of air according to newtons third law.

Question 25

what is lift?

Answer 25

an aerodynamic force which is perpendicular to the relative airflow

Question 26

what is drag?

Answer 26

an aerodynamic force parallel to the relative airflow, which opposes the motion of an aerofoil

Question 27

what is total reaction?

Answer 27

total reaction is the combination of a rise in pressure under the wing and a reduction in pressure above the wing

Question 28

is air an ideal fluid? why/why not?

Answer 28

no - air is compressible and has viscosity

Question 29

wherever the speed of airflow is increased, the air gains dynamic energy and its static pressure is accordingly (increased/reduced)

Answer 29

reduced

Question 30

what is a streamline airflow?

Answer 30

a flow of air in which particles follow a steady and predictable path

Question 31

what is the venturi effect?

Answer 31

air is forced to speed up when passing through a venturi due to the bernoulli theorem - static pressure is drastically decreased at the throat of the venturi, because dynamic pressure is at its highest

Question 32

whats the most effective AoA?

Answer 32

4 degrees

Question 33

airflow above an aerofoil (speeds up/ slows down), resulting in an (increased/decreased) static pressure

Answer 33

speeds up, decreased

Question 34

around an aerfoil, there are areas of (lower/higher) pressure, and the top area is (more/less) dramatic than the bottom area

Answer 34

lower, more

Question 35

as AoA increases, CoP moves ___

Answer 35

forward until the critical angle, at which it falls backwards

Question 36

general critical angle on a GP aerofoil is about ___ degrees

Answer 36

15

Question 37

what is upwash?

Answer 37

the air deflected above an aerofoil

Question 38

what is downwash?

Answer 38

the air deflected below an aerofoil

Question 39

total reaction (increases/decreases) with increasing AoA until critical angle

Answer 39

increases

Question 40

at low AoA, CoP is about ___% back from the LE

Answer 40

30-40

Question 41

at high AoA, CoP is about ___% back from the LE

Answer 41

15-20

Question 42

total reaction (TR) is made up of two component forces. they are:

Answer 42

lift and drag