lift

Question 1

equation of continuity

Answer 1

mass of air entering the pipe in a given time will equal the mass of air leaving the pipe in the same time

Question 2

what effect does cross sectional area have on air flowing through a pipe?

Answer 2

when cross sectional area reduces, the velocity of the air increases

Question 3

bernouilli’s theorem

Answer 3

when fluid flows at a steady rate through a pipe, its total energy remains constant.

as total pressure must remain constant, an increase in velocity means static pressure must decrease.

Question 4

describe the difference of static pressure around an aerofoil

Answer 4

velocity decreases more on the top of the wing than on the bottom. therefore, static pressure drops more on top of the wing. upwards force of lift created by static pressure difference.

Question 5

angle of attack

Answer 5

angle between the relative airflow and the chord line of an aerofoil

Question 6

angle of incidence

Answer 6

angle between the aircraft longitudinal axis and the wing chord line

Question 7

where do stagnation points form?

Answer 7

at the leading and trailing edges

Question 8

what is the static pressure at the stagnation points?

Answer 8

static pressure is at its maximum

Question 9

for an asymmetric aerofoil, what AoA will give 0 lift?

Answer 9

-4°

Question 10

what portion of the aerofoil produces the most amount of lift?

Answer 10

the upper surface of the wing produces the greatest amount of lift at all speeds

Question 11

what is the centre of pressure?

Answer 11

the overall effect of the changes in static pressure can be shown ad the total reaction.

the TR acts through a single point on the chord line called the centre of pressure

Question 12

lift is ___ to the relative airflow

Answer 12

perpendicular

Question 13

drag is ___ to the relative airflow

Answer 13

parallel

Question 14

as AoA increases, what happens to the centre of pressure?

Answer 14

CP moves towards the leading edge. TR increases in magnitude