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Aerodynamics > Aerodynamics > Flashcards

Aerodynamics Flashcards

1
Q

What is the kinetic energy equation?

A

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

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2
Q

What is laminar flow?

A

Smooth regular airflow patterns around an object

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3
Q

What is turbulent flow?

A

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

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4
Q

What is the continuity equation?

A

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

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5
Q

What is Bernoullis Principle?

A

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

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6
Q

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

A

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

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7
Q

Dynamic pressure can also be referred to as what?

A

Indicated airspeed (pitot pressure)

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8
Q

Describe the point of stagnation

A

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

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9
Q

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

A

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

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10
Q

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

A

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

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11
Q

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

A

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

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12
Q

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

A

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

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13
Q

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

A

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

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14
Q

How does an aerofoil create lift?

A

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)

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15
Q

What is the chord of an aerofoil?

A

A straight line connecting leading edge and trailing edge

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16
Q

What is camber of a aerofoil?

A

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

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17
Q

What is the fineness ratio?

A

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

18
Q

What is aspect ratio?

A

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

19
Q

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

A

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

20
Q

For most aerofoils what is considered the maximum AOA?

A

15-18 degrees

21
Q

What type of drag are wing tip vortices?

A

Induced drag formed by spanwise flow

22
Q

Profile/Parasitic/Form Drag is reduced by what?

A

Streamlining

23
Q

How does induced drag react with an increase in altitude?

A

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

24
Q

How is the thrust to weight ratio calculated?

A

Ratio = thrust / weight

25
Q

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

A

Perpendicular to relative wind

26
Q

Wing loading equation?

A

Wing loading = weight / wing area

27
Q

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

A

Root stalls first (most desirable)

28
Q

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

A

Wing tip first

29
Q

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

A

Critical Mach number - Mcrit

30
Q

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

A

Vmd (minimum drag)

31
Q

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

A

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

32
Q

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

A

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

33
Q

How does induced drag change with increases in altitude?

A

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

34
Q

What is the Magnus effect?

A

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

35
Q

What is the Magnus effect?

A

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

36
Q

What is the coefficient of lift equation?

A

Lift = Cl x 1/2 p x v^2 x A

If anything after the = increases lift and drag increase

37
Q

Wing loading equation?

A

Wing loading = weight
—————
Wing area

38
Q

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

A

Ratio of lift to weight during manoeuvres

LF = lift in a turn
—————-
Weight

39
Q

Stall speed is defined as what?

A

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

40
Q

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

A

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

Aerodynamics (3 decks)

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