Aerodynamics

Question 1

What is the kinetic energy equation?

Answer 1

KE = 1/2 x p x V^2
Kinetic Energy = 1/2 x density x velocity squared

Question 2

What is laminar flow?

Answer 2

Smooth regular airflow patterns around an object

Question 3

What is turbulent flow?

Answer 3

When airflow is disturbed and separates from the surface of the body

Question 4

What is the continuity equation?

Answer 4

V1 x A1 = V2 x A2
Speed of airflow is inversely proportional to the cross sectional area if density remains constant.

Question 5

What is Bernoullis Principle?

Answer 5

P tot = p + q
Total pressure = static pressure + dynamic pressure
Total pressure remains constant

Question 6

Which regards to bodies in motion what is the dynamic pressure equation?

Answer 6

q = 1/2 x p x v^2
Dynamic pressure = 1/2 x density x velocity squared

Question 7

Dynamic pressure can also be referred to as what?

Answer 7

Indicated airspeed (pitot pressure)

Question 8

Describe the point of stagnation

Answer 8

When the speed of the airflow falls to zero and static pressure is equal to total pressure.
No dynamic pressure means there is no flow

Question 9

In an Venturi tube what are the air pressures doing at the inlet?

Answer 9

Dynamic pressure (q) is low
Static pressure (p) is high
Velocity (V) is low

Question 10

In an Venturi tube what are the air pressures doing at the narrowest point of the tube?

Answer 10

Dynamic pressure (q) is high
Static pressure (p) is low
Velocity (V) is high
Static pressure reduces as velocity and dynamic pressure increase into the narrow duct

Question 11

In an Venturi tube what are the air pressures doing at the diffuser outlet of the tube?

Answer 11

Dynamic pressure (q) reduces
Static pressure (p) increases
Velocity (V) reduces

Question 12

How is the Venturi tube theory affected as the airflow reaches the speed of sound?

Answer 12

The pressures at the inlet, narrow point and outlet are the opposite

Question 13

What is the relationship between dynamic and static pressure with the introduction of an aerofoil into the airflow?

Answer 13

Wing upper surface will have higher dynamic pressure and lower static pressure, wing lower surface has unchanged static pressure.

Question 14

How does an aerofoil create lift?

Answer 14

The difference in static pressure between lower and upper surface. Higher static below trying to move towards upper surface lower static pressure creates the lift. (HIGH PRESSURE MOVING TO LOW)

Question 15

What is the chord of an aerofoil?

Answer 15

A straight line connecting leading edge and trailing edge

Question 16

What is camber of a aerofoil?

Answer 16

Mean camber line is a line drawn equidistant between upper and lower surfaces of the profile
Typically 5% located 45% aft of leading edge

Question 17

What is the fineness ratio?

Answer 17

Maximum thickness or depth expressed as a percentage of the chord
Typically 18% located 30% aft of leading edge

Question 18

What is aspect ratio?

Answer 18

Ratio between length and average width of the surface
AR = wing span ^2
——————-
Wing area (mean wing chord)

Question 19

At normal cruising airspeed with a small positive angle of attack, where is the CP positioned on the wing/chord line?

Answer 19

Approximately 25% back from the leading edge on the chord line

Question 20

For most aerofoils what is considered the maximum AOA?

Answer 20

15-18 degrees

Question 21

What type of drag are wing tip vortices?

Answer 21

Induced drag formed by spanwise flow

Question 22

Profile/Parasitic/Form Drag is reduced by what?

Answer 22

Streamlining

Question 23

How does induced drag react with an increase in altitude?

Answer 23

It increases, as density decreases more lift required thus more induced drag

Question 24

How is the thrust to weight ratio calculated?

Answer 24

Ratio = thrust / weight

Question 25

In the aerodynamic resultant, which direction does lift always act?

Answer 25

Perpendicular to relative wind

Question 26

Wing loading equation?

Answer 26

Wing loading = weight / wing area

Question 27

With a rectangular wing shape which stalls first tip or root?

Answer 27

Root stalls first (most desirable)

Question 28

With a swept wing, at what point does the wing stall? Root or tip?

Answer 28

Wing tip first

Question 29

What term describes the speed at which shock waves begin to form?

Answer 29

Critical Mach number - Mcrit

Question 30

With reference to the drag curves, at the point where induced drag and form/parasitic drag meet is know by what acronym?

Answer 30

Vmd (minimum drag)

Question 31

At lower speed, how does it affect AOA and induced drag?

Answer 31

At lower speeds more lift required, higher angle of attack and thus more induced drag

Question 32

At higher speed, how does it affect AOA and induced drag?

Answer 32

At higher speeds, less lift required to be produced thus less induced drag meaning higher efficiency

Question 33

How does induced drag change with increases in altitude?

Answer 33

Induced drag increases as more lift is required at altitude assuming constant speed

Question 34

What is the Magnus effect?

Answer 34

A cylinder in free stream air with added mechanical clockwise rotation produces net lift Air over the upper edge is accelerate, air beneath the cylinder is slowed

Question 35

What is the Magnus effect?

Answer 35

A cylinder in free stream air with added mechanical clockwise rotation produces net lift

Question 36

What is the coefficient of lift equation?

Answer 36

Lift = Cl x 1/2 p x v^2 x A *If anything after the = increases lift and drag increase*

Question 37

Wing loading equation?

Answer 37

Wing loading = weight ————— Wing area

Question 38

Which of the following best describes load factor? Ratio of lift to drag Ration of weight to wing area Ratio of lift to weight during maneuvers

Answer 38

Ratio of lift to weight during manoeuvres LF = lift in a turn —————- Weight

Question 39

Stall speed is defined as what?

Answer 39

The minimum airspeed at which an aircraft can maintain level flight. The speed below which the wings cannot generate enough lift to support the weight

Question 40

What happens to an aircraft’s stall speed as weight increases? Stall speed decreases Stall speed increases Stall speed remains the same

Answer 40

Stall speed increases. The minimum speed required to maintain lift is raised with added weight