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M8 > Lesson 1 > Flashcards

Lesson 1 Flashcards

1
Q

What are the percentages of gasses in the air

A

21% oxygen
78% nitrogen
1% Other gases

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2
Q

What are the 5 main regions of the atmosphere and what order are they in

A

The Troposphere
Stratosphere
Mesosphere
Thermosphere
Exosphere

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3
Q

How far does the troposphere extend

A

starts at the Earth’s surface and extends 8 to 14.5 kilometres high

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4
Q

Define the tropopause

A

The tropopause is a thermodynamic gradient-stratification layer that marks the end of the troposphere.

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5
Q

Why would aircraft cruise through the tropopause

A

The air is thinner, resulting in less drag

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6
Q

Where is the stratosphere

A

Above the troposphere, extends to 50km above ground

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7
Q

What is the constant temperature at the stratosphere

A

-56.5 degrees Celsius

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8
Q

What is the Atmospheric pressure at sea level

A

14.7 psi
1 atm
29.92 in Hg
760 mmHg
101.325 hPa
101325 N/m^2

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9
Q

Why does the temperature at height change

A

Due to convection

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10
Q

What is the temperature at sea level

A

15 °C

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11
Q

What is the relative density at sea level

A

100%

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12
Q

What is the relationship with density and pressure

A

They are proportional

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13
Q

What is the relationship with density or pressure with height

A

They are inversely proportional

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14
Q

What happens to density when humidity increases

A

Density decreases

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15
Q

What 3 things all affect air density

A

Pressure, temperature and density

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16
Q

What are the ISA values at sea level for: pressure, density and temperature

A

Pressure 1013.25 hPa.
Density 1.225 kg/m3
Temperature 288.15 K or 15 °C

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17
Q

Define speed

A

Speed is the distance that a moving object covers in a unit of time.

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18
Q

Define acceleration

A

Acceleration is the change in speed divided by the time during which the change takes place.

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19
Q

What is work

A

Work is done when an object is moved over a distance. It is force multiplied by distance:

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20
Q

What is power

A

Power is work over time, or more specifically force multiplied by distance over time.

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21
Q

What is the speed of sound denoted by

A

a

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22
Q

What is the speed of sound equation

A

20X ✓t m/s

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23
Q

Why is the speed of sound lower at higher altitudes

A

Because the temperature is lower

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24
Q

Why is air considered an ideal fluid

A

Due to its low internal friction

25
Q

What is the formula of airflow around a body

A

KE= 1/2p x V^2

Answer in joules
p is the local air density

26
Q

what is a streamline/ stream flow

A

stream flow is when the particles of a fluid move in an orderly manner and maintain relative positions in successive cross sections

27
Q

When is the term “diffuser outlet” used

A

when the diameter increases and the speed decreases.

28
Q

When is the term “jet outlet” used

A

when the diameter decreases and the speed increases.

29
Q

What is the physical law known as Bernoulli’s principle

A

Ptot= p+q

30
Q

What is the equation of static pressure

A

q= 1/2p x V^2

31
Q

What is the “boundary layer”

A

The boundary layer is the layer of fluid in the immediate area of a surface.

32
Q

Define laminar flow

A

Laminar flow is when particles in the fluid all flow parallel to one another, in layers, with the streamlines not crossing each other.

33
Q

What are vortices

A

Vortices are circular patterns of rotating air formed behind a wing or control surface as it generates lift or a force from the pressure differential.

34
Q

What happens to the boundary layer if the aircraft velocity is increased, if the fluid viscosity is decreased or the fluid density is increased.

A

It becomes thinner

35
Q

What way is air required to flow in laminar flow

A

From a low pressure to a high pressure

36
Q

What is free-stream flow

A

Free Stream Flow is fluid far enough away from a moving body that is unaffected by the body moving through the fluid.

37
Q

What is relative airflow

A

Relative Airflow is the direction of the airflow with respect to the object moving through it.

38
Q

What is A stagnation point

A

A stagnation point is a region of space around the aircraft where the velocity of the relative airflow is Zero.

39
Q

What is the “angle of attack”

A

The angle of attack is the angle between the chord line of the profile and the relative wind

40
Q

What is a disadvantage of laminar flow

A

due to the lower kinetic energy contained, it is easier for flow separation to occur.

41
Q

What are the advantages of laminar flow

A

The advantages of laminar flow are less surface friction giving rise to low fuel usage, giving greater range, a faster top speed for given fuel usage and the ability to glide further in the event of engine failure.

42
Q

What is the chord line and the chord

A

The chord line is a straight line connecting the leading edge and the trailing edge.

The chord is the distance between the leading and trailing edges measured along the chord line.

43
Q

What is the camber line and the camber

A

The mean camber line is a line drawn equidistant between the upper and the lower surfaces of the profile.

The camber of the profile is the displacement of the mean camber line from the chord line.

44
Q

What is the Fineness ratio

A

is the maximum thickness or depth of a section expressed as a percentage of the chord from the leading edge to the trailing edge.

45
Q

What is an aspect ratio? And what is the formula

A

The aspect ratio of an aerofoil is the ratio between the length and the average width of the surface.

AR= wing span^2/ wing area

46
Q

What is the relationship with aspect ratio and drag

A

They’re inversely proportional

47
Q

What is the angle of incidence?

A

The angle of incidence is the angle between the chord line of the profile and the longitudinal axis of the aircraft.
Denoted by y (gamma)

48
Q

What is the centre of pressure?

A

is the point on the chord line where the total sum of a pressure field acts on a body

49
Q

Define “wash in”

A

“Wash in” refers to an angle of incidence that is greater toward the wing tips
Wash out is vice versa

50
Q

What are the two types of twisted wing

A

Geometrically and aerodynamically twisted wing

51
Q

What is the mean aerodynamic chard

A

The Mean Aerodynamic Chord (MAC) is the average chord length of a tapered or swept wing.

52
Q

What are the four different wing types

A

An elliptical wing
A rectangular wing
A tapered wing
A swept wing

53
Q

What is the sweep angle?

A

The sweep angle is the angle between the line of 25 percent chords and a line perpendicular to the root chord.

54
Q

What is positive dihedral

A

When a wing has a wingtip higher than the root, it is described as a dihedral.

55
Q

What is negative dihedral

A

On aircraft with a negative dihedral, the wing tips are lower than the wing root.

56
Q

What is the total aircraft drag sum?

A

Induced Drag
Parasite Drag: drag
Compressible Drag

57
Q

How is an airplanes thrust determined

A

determined by the size and type of propulsion system used on the aircraft and on the throttle setting selected by the pilot.

58
Q

How is an airplanes weight determinant

A

The weight of an aircraft is determined by the size and materials used in the aircraft’s construction and on the payload and fuel that it carries.

59
Q

What is the coefficient of lift and drag

A

Measured lift/ theoretical lift
Measured drag/ theoretical drag

M8 (2 decks)

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