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Mod 8 basic aerodynamics > 8.2 aerodynamics > Flashcards

8.2 aerodynamics Flashcards

1
Q

what is turbulent air?

A

air moving through a disturbance
it becomes turbulent when the air separates

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2
Q

what is laminar flow?

A

smooth regular air flow

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3
Q

air particles have a mass so what does this result in?

A

air in motion possesses a momentum

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4
Q

what does air exert pressure on?

A

on any objects in its path

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5
Q

what is the relationship between dynamic pressure density and velocity?

A

it is proportional to density and the square of velocity

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6
Q

what is energy due to and what is the equation for that?

A

due to kinetic energy
KE = 1/2 *v^2

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7
Q

what happens when a volume of air is completely trapped and brought in an open ended tube?

A

total energy remains constant and the moving air exerts pressure on the tube and kinetic energy is passed

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8
Q

what can and can not be done to energy and mass?

A

can be neither be created or destroyed
can only change states

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9
Q

what is streamline / free stream?

A

when particles of a fluid move in an orderly manner and maintain relative position in successive cross section

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10
Q

what is cross section represented by?

A

lines running parallel to one another hugging the shape of the body it is following around

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11
Q

in the subsonic region a flying body does not attain what?

A

the speeds necessary to compress the air

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12
Q

where is the air incompressible?

A

in the subsonic region

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13
Q

if there is no disturbance the air is what?

A

air is streamline and parallel

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14
Q

when something is streamlined it is what?

A

it is similar to the flow in a closed tube

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15
Q

what happens when the tube gets smaller in laminar flow?

A

the air flow remines equally spaced when it is in a tube with different diameter’s

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15
Q

what does the continuity equation state?

A

that the speed of the airflow is inversely proportional to the cross section if density remains the same
p1 = p2 so v1 * a1 = a2 * v2

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16
Q

when will v1 * a1 = v2 * a2 be used?

A

when there is a difference in volume

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17
Q

when is there a diffuser outlet?

A

when diameter increases and speed decreases

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18
Q

when is there a jet outlet?

A

when the diameter decreases and speed increases

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19
Q

in Bernoulli’s principle what happens when the valve is closed?

A

the tube is filled with fluid on the left side of the valve

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20
Q

when the valve is closed what pressure will there be and where?

A

the fluid filled on the inside of the tube has static pressure

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21
Q

in Bernoulli’s principle when the valve is closed where does pressure act?

A

acts in all directions

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22
Q

what is total pressure represented by in Bernoulli’s principle?

A

a green circle

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23
Q

in Bernoulli’s principle what is the relationship between total pressure and static pressure when the valve is closed?

A

total pressure is equal to static pressure

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24
Q

how is Bernoulli’s printable explained?

A

explained with a valve

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25
Q

when the vale is open what happens to static and dynamic pressure?

A

static pressure decreases
dynamic pressure increases

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26
Q

in Bernoulli’s principle what pressure is introduced?

A

dynamic pressure

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27
Q

when the valve is open what pressure remains unchanged?

A

total pressure

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28
Q

what is the equation for total pressure and constant pressure?

A

total Pout = p * q
constant q = 1/2 *v^2

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29
Q

what is the equation for dynamic pressure?

A

dynamic pressure = total pressure - static pressure

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30
Q

where is static pressure sensed?

A

directly at the static port

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31
Q

what is static and dynamic pressure indicated by?

A

static pressure is a red line
dynamic pressure is a blue line

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32
Q

what is dynamic pressures relationship to density and velocity for bodies in motion?

A

dynamic pressure is proportional to density and square of relative velocity

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33
Q

what will happen if we assume density is constant?

A

dynamic pressure increases 16 times and speed increases 4 times

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34
Q

what is dynamic pressure indicated to the pilot by?

A

induced air speed

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35
Q

what happens at the point of stagnation?

A

speed of the airflow falls to zero an static pressure = total pressure

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36
Q

if there is no dynamic pressure there is no what?

A

there is no air flow

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37
Q

in the venturi tube what is the same?

A

the inlet and outlet

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38
Q

in the venturi tube airspeed of airflow increases until what point?

A

until it reaches the narrowest point

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39
Q

what happens to speed, static pressure and dynamic pressure in a venturi tube?

A

speed increases
static pressure decreases
dynamic pressure increases

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40
Q

what happens at the narrowest point of a venturi tube?

A

speed decrease after the narrowest point
static pressure increases
dynamic pressure decreases

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41
Q

in the venturi tube it says what causes lift?

A

the difference in static pressure

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42
Q

what is a fixed boundary layer?

A

it is where the air stream close to the skin has a velocity of zero

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43
Q

what is the boundary layer?

A

it is a layer of fluid in the immediate surface of the skin

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44
Q

when air moves over the wing the fluid at the skin of the surface can be said to be what?

A

it can be considered stationary as monocles of the surface are brought to rest by friction

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45
Q

why is the surface rough on the skin?

A

because of imperfections but then monocles become caught there forcing them to become stationary

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46
Q

what happens because of the rough surface on the skin?

A

the second layer shears because of rough surface

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47
Q

when will layer begin to stop shearing?

A

until the layer of the air particles reach the velocity of the free stream

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48
Q

what is laminar flow?

A

smooth and undisturbed and less energetic flow

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49
Q

is laminar flow easy to achieve?

A

no

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50
Q

in laminar flow the layers are what?

A

layers are streamlined and do not cross over each other
they flow parallel to each other

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51
Q

what will rivets do to laminar flow?

A

rivets will disturb the laminar flow

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52
Q

when looking at laminar flow when is the pressure gradient negative?

A

from the thickest point of the wing to the trailing edge

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53
Q

what will happen if the flow is insufficient in terms of laminar flow and when will it worsen until?

A

it will detach from the surface and start to travel in the reserve direction #
will worsen until the wing stalls

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54
Q

where is laminar flow easier to obtain and why?

A

easier to achieve at the leading edge because there is a positive gradient

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55
Q

is laminar flow desirable and why?

A

it is desirable because it gives high lift and low skin friction and drag

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56
Q

what is lower drag due to in terms of laminar flow and why is it caused?

A

it is due to shear stress on the boundary layer

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57
Q

what is more likely to form turbulent floe or laminar flow and why?

A

turbulent flow because it is more naturally occurring

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58
Q

in turbulent flow what happens at the surface of the wing?

A

particles move at zero velocity and still cause very laminar flow

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59
Q

in turbulent flow where do imperfections extend?

A

they extend beyond the laminate layer

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60
Q

what does the mixture of laminar flow and free stream air cause in turbulent flow?

A

the mixture become chaotic and difficult to predict

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61
Q

what are eddies caused by?

A

formed when influences of the air nearby by and cause further disruption

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62
Q

what is difficult to maintain over a wing?

A

laminar flow

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63
Q

when does airflow naturally become turbulent?

A

becomes turbulent with an increase in AOA causing pressure gradient
this occurs at lower airspeeds if there are any imperfections on the wing

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64
Q

what is the negative of laminar flow?

A

this flow increases drag because layers do not slide over each other

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65
Q

turbulent flow causes this boundary layer to become what?

A

to become thicker and more energetic

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66
Q

what does turbulent flow allow that laminar flow does not?

A

for grater negative pressure

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67
Q

what is a positive of turbulent flow?

A

allows the boundary layer to remain attached to wing but laminar flow would have separated which reduces pressure drag

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68
Q

in free stream flow the fluid id what?

A

far enough away from the moving body

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69
Q

in free stream flow what happens as the aircraft moves through the air?

A

it affects the air around the aircraft causing it to change direction, heat up, change velocity and pressure

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70
Q

when do the effects of free stream flow decrease?

A

as distance increases from the aircraft

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71
Q

what is relative airflow?

A

the direction of the airflow with respect to the object moving through it

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72
Q

a climbing aircraft will have more what?

A

will have a grater nose up altitude

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73
Q

relative airflow is usually what?

A

an angle to the nose

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74
Q

in level flight the aircraft is doing what?

A

aircraft is flying directedly into the wind

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75
Q

in climb wind would appear to come from where?

A

appear to come from bellow the aircraft

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76
Q

in decent wind would appear to come from where?

A

would appear to come from above the aircraft

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77
Q

what is the stagnation point?

A

the region of space around the aircraft where the velocity of relative airflow is zero

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78
Q

what does the stagnation point result in?

A

results in static pressure compared to the surrounding fluid moving relative to the aircraft

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79
Q

where is the common point of stagnation?

A

the leading edge of the wings

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80
Q

the boundary layer can be what?

A

can be laminar or turbulent

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81
Q

the boundary layer is not always what?

A

is not always smooth or laminar

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82
Q

where is the laminar boundary layer located?

A

immediately downstream of the wing leading edge

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83
Q

what does turbulent boundary layer produce?

A

produces higher kinetic energy

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84
Q

where is the transition point of a wing?

A

at or near the maximum thickness and the lowest point of pressure

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85
Q

what do small disturbances inside the boundary layer do?

A

brig it to a turbulent boundary layer of produce floe separation

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86
Q

what does an increase in AOA do to the transition point?

A

brings the transition point further forward and an adverse pressure gradient becomes stronger

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87
Q

what may happen if there is not enough wing area?

A

not enough area so wing may stall

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88
Q

what causes thrust effect on the wing?

A

high pressure to lo pressure

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89
Q

wat does air movement cause?

A

pressure drop and following air flows from high pressure to low pressure

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90
Q

when flow is from low to high pressure wat happens?

A

the lower kinetic energy of laminar flow will lack the energy required to force it to flow against the negative pressure

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91
Q

wat will resulting pressure gradient on a wing cause?

A

air to flow from high to low pressure

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92
Q

in flow separation streamlines over the wing will do what?

A

will separate and travel over the layer of air traveling in the reverse direction

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93
Q

wat happens when flow is separating?

A

lift is reduced and pressure drag increased dramatically

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94
Q

wat boundary layer is more energetic?

A

turbulent boundary layer

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95
Q

wen would prevention of flow separation happen?

A

if the flow was laminar

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96
Q

where is it safer for a stall on the wing?

A

at the root rater than the tip

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97
Q

sacrificing loamier flow towards the wing tips does what?

A

helps control a stalling aircraft

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98
Q

what is the main advantage of laminar flow?

A

the surface has friction which saves fuel, increases range, increases sped and further glide in failure

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99
Q

it is easy to chive laminar flow?

A

no especially at high speeds and AOA
difficult to achieve in negative pressure gradient from thickest part of the wing and trailing edge

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100
Q

when a wing has laminar flow and stalls what does it create?

A

high pressure drag witch increases stall further

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101
Q

what is the disadvantage of laminar flow?

A

has lower kinetic energy so easier for flow separation to occur

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102
Q

what is downwash?

A

after passing over the airfoil it returns to its original shape

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103
Q

wat is upwash?

A

as air flows towards the wing it turns towards the low pressure region of the upper surface of te airfoil

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104
Q

what happens at the leading edge with the airflow?

A

the airflow stagnates annd seperates as it passes under the wing

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105
Q

what happens when air flows back over the airfoil?

A

4it will slow down and flow against adverse pressure gradient as high pressure bellow the wing wants to go from high pressure to low pressure

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106
Q

what do door gutters do?

A

they slope upwards to reflect upwash and downwash and reflect AFT of the wing

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107
Q

on finite wingspans what must be considered?

A

wing tip vortices must be considered

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108
Q

if wingspan is infinite what does the circulation around the profile cause?

A

upwash on LE and downwash on the TE known as bound vortex

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109
Q

as the vortices get stronger what happens?

A

enhanced drag gets grater

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110
Q

what i induced drag?

A

increase in drag

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111
Q

to ensure enough lift is generated what is needed?

A

a higher AOA is needed

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112
Q

wat is induced alpha?

A

is the angle between effect airflow and relative airflow

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113
Q

what is an increase in drag caused by?

A

the need to maintain lift

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114
Q

trailing vortices have a strong influence on what?

A

lift
drag
handling properties

115
Q

wat do vortices produce?

A

produce downwash of flow behind the wing

116
Q

which way to vortices rotate on left wing and right wing?

A

rotate clockwise at the wing tip
rotate anti clockwise at the wing tip

117
Q

what are vortices?

A

circular patterns or rotating air formed behind a wing or control surface

118
Q

what does an aerodynamic profile have?

A

leading and trailing edge

119
Q

what is the chord line?

A

a straight line connected LE to TE the distance between the two is measured

120
Q

what is the mean chord line?

A

a line drawn equidistant between upper and lower surface of the profile

121
Q

wat is the camber of a profile?

A

it is the displacement of the mean camber from the chord line

122
Q

wat is maximum camber?

A

the greatest distance between mean camber line from the chord line
expressed as a pentane of the chord line

123
Q

when is there a positive and negative camber?

A

positive when the camber is above the chord line
negative when the camber i bellow the chord line

124
Q

why is the shape of the mean camber important?

A

in determining aerodynamic characteristics of a profile

124
Q

does a symmetrical airfoil have a camber? why?

A

has no camber as the chord and camber are the same

125
Q

a typical low speed profile has what camber and AOA?

A

has a max camber of 5% at 45% AOA of the leading edge

126
Q

on fineness ratio what is the maximum thickness?

A

depth of a section expressed as a percentage from the LE to the TE

127
Q

wat is the line of maximum thickness defined as?

A

a percentage of the chord

128
Q

what is a high aspect ratio used for?

A

high performance gliders

129
Q

how can you change the aspect ratio in flight?

A

by pivoting the wings to have a large span for low speeds

130
Q

where is induced drag less?

A

less on an aircraft with a high aspect ratio

131
Q

wing tips can be designed to reduce what?

A

induced drag

131
Q

what does high aspect ratio have?

A

has lower drag and slightly higher lift

132
Q

wat is induced drag affected by?

A

aspect ratio
wing tip design
aircraft speeds

133
Q

low aspect ratio looks like what?

A

short spans or thick chords

134
Q

airfoil is the ratio between what?

A

ratio between length and average width of the surface

135
Q

what is aspect ratio?

A

ratio of wing length to average chord of the wing

136
Q

what is the equation for aspect ratio if chord is equal thought?

A

AR = length of wing / width of the wing

137
Q

wat is the equation for aspect ratio if the chord line is varied thought?

A

AR = wing span^2 / wing area

138
Q

wat does wash in refer to?

A

when the angle of incidence is grater towards the tip

139
Q

wat does wash out refer to?

A

when the angle of incidence is grater towards the root

140
Q

wings cam be designed so what can happen?

A

so they stall at the root before the tips so aircraft remains controllable

141
Q

in geometrically twisted wings what does the camber look like?

A

constant across the span of the wing

142
Q

on geometrically twisted wings where is the angle of incidence grater?

A

grater at the root

143
Q

are the chord lines parallel in geometrically twisted wings?

A

no

144
Q

with aerodynamically twisted wings where is the camber grater?

A

at the root

145
Q

wat does the angle of incidence look like for aerodynamically twisted wings?

A

angle of incidence is constant across the wingspan

146
Q

ae the chord lines parallel on aerodynamically twisted wings?

A

yes

147
Q

what happens on a aerodynamically twisted wing at the stall speeds?

A

there is flow separation t he root before the twist

148
Q

most aircraft wings are what?

A

tapered and swept and use a combination of gyrometric and aerodynamic wash out

149
Q

what is the mean aerodynamic chord?

A

the average chord length of a tapered or swept wing

150
Q

were is the angle of incidence?

A

between the chord line and the longitudinal axis of the aircraft

151
Q

what is the angle o incidence used for?

A

for fixed wing but an be variable for the tailplane and horizontal stabilizer

152
Q

were is the center of pressure?

A

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

153
Q

what is aerodynamic force and where does it act?

A

it is called total reaction and acts around the center of pressure

154
Q

what can the center of pressure be broken down into?

A

into parallel and perpendicular to relative airflow

155
Q

is drag parallel or perpendicular?

A

drag is parallel in the same direction as relative airport

156
Q

when at normal cursing speeds and small AOA where is the center of pressure of the chord line?

A

25% of the cord line

157
Q

what happens to the center of pressure when AOA increases?

A

AOA increases the center of pressure moves forward

158
Q

what is the max AOA before flow separation occurs?

A

15% to 18%

159
Q

what are the 4 different types of wing shape?

A

elliptical wing
rectangular wing
tapered wing
swept wiing

160
Q

why is there different stall characteristics of different wings?

A

the down wash behind the wing changes the local angle of attack

161
Q

what are the characteristics of an elliptical wing?

A

has constant down wash behind the wing
constant down wash gives constant AOA and constant flow separation across the span of the wing
entire wing stalls at the same time

162
Q

what are the characteristic of a rectangular wing?

A

has large wing tip vortices so larger downwash at the tip
has higher down wash and lower AOA at tip
tip sections are last to stall

163
Q

what are the characteristics of the tapered wing?

A

down wash increases towards the root
tip stalls first

164
Q

what are the characteristics of swept wings?

A

tends to stall at the tip first
used on most aircraft
impacts lateral and controllability because of tip stall

165
Q

what is the seep angle?

A

between the line of 25% chord and line perpendicular to the root chord

166
Q

what is positive and negative sweep?

A

positive sweep = backwards
negative sweep = forwards

167
Q

what happens when the wing is more swept?

A

the more stable the aircraft is on the roll axis

168
Q

what is a dihedral angle?

A

when the wing tips are higher thana the root

169
Q

what do dihedral angles increase?

A

roll stability
AOA
lift what are anhedral angles?

170
Q

what aircraft use dihedral angles?

A

commercial aircraft

171
Q

what are anhedral angles?

A

wing tips are lower than the wing root

172
Q

what is the effects of anhedral angles?

A

increase roll performance
reduces the amount of lift
counteract roll
provide balance and stability and maneuverability

173
Q

what aircraft are anhedral wings used on?

A

aircraft that require high agility and memorability

174
Q

what is drag?

A

aerodynamic force witch is parallel to the relative wind

175
Q

what is the total aircraft drag the sum of?

A

induced drag
parasite drag
compressible drag

176
Q

what is induced drag?

A

drag cause by lift

177
Q

what is parasite drag?

A

caused by distribution of pressure
sum of friction
not related to lift

178
Q

what is compressible drag?

A

caused by shockwaves when aircraft reaches the speed of sound

179
Q

what is the movements of induced drag?

A

movements of air over wing starts at fuselage and makes way to wing tip

180
Q

on induced drag where is spanwise flow the strongest?

A

at the wing tips so vortices at the trailing edge of the wing

181
Q

with induced drag where is static pressure higher?

A

is lower above the wing
higher bellow the wing

182
Q

what type of drag has strong vortices?

A

induced drag

183
Q

what do induced drag vortices do to the aircraft?

A

contribute to drag so aircraft becomes less efficient

184
Q

when is there a high lift coefficient?

A

when at low speeds as there is a higher AOA

185
Q

when does an aircraft has a low lift coefficient?

A

when at low speeds and low AOA

186
Q

what happens when there is a low pressure difference between the upper and lower surface of the wing?

A

creates small wing tip vortices so therefore lower drag

187
Q

what is parasite drag cause by?

A

pressure distribution over a body
difference in pressure

188
Q

what does form drag depend on?

A

friction area of a body and the speed of the airflow

189
Q

when there is no friction there is no what?

A

drag
because the pressure before and after is the same

190
Q

when there is airflow with friction is there a pattern?

A

there is no symmetrical pattern

191
Q

is pressure the same on airflow with friction?

A

pressure is not the same

192
Q

what types of drag have a relationship?

A

form and friction drag

193
Q

when a profile has low foam drag and high from drag what goes along with it?

A

low form drag = high friction drag
high form drag = low friction drag

194
Q

what is more toral drag or drag on each wing?

A

total drag

195
Q

where is there drag felt?

A

wing
strut
engine

196
Q

how can interference drag be reduced?

A

adding faring’s witch is found on wing roots, pylons, flap tracks

197
Q

define interference drag?

A

turbulence in airflow caused by sharp corners and joints

198
Q

what happens to the boundary layer as it passes through the shockwave?

A

it thickens

199
Q

is the shockwave Infront or behind the shockwave?

A

Infront and behind

200
Q

where does compressible drag occur?

A

in transonic and supersonic

201
Q

in compressible drag what happens when in the transonic region?

A

there is a mixture of subsong and supersonic airflow and encourages shockwaves

202
Q

what happens in compressible drag in supersonic flight?

A

vortices move faster than free stream
velocity os less than speed of sound

203
Q

where does flow separation occur?

A

as boundary layer thickens

204
Q

air sped varies due to thrust but what else must happen?

A

AOA must vary to maintain level flight

205
Q

what must happen to maintain constant airspeed?

A

thrust and drag must remain equal

206
Q

what must the pilot do to ensure straight and kevel flight?

A

coordinate AOA and thrust

207
Q

what is the weight of the aircraft?

A

size and martials used on aircraft
fuel carried

208
Q

what is the relationship between weight and lift?

A

definitive

209
Q

what happens when lift is grater than weight or when weight is grater than lift?

A

when lift is less than weight vertical speed wil increase
when lift is grater than lift vertical speed will increase

210
Q

why is lift required?

A

to counteract the weight

211
Q

what is lift?

A

upward force on the wing perpendicular to the relative wind and lateral axis

212
Q

what happens when lift force is equal to the weight force of the aircraft?

A

it is at a state of equilibrium and nether accelerates upwards or downwards

213
Q

thrust to weight ratio is an efficacy factor for what?

A

total aircraft propulsion

214
Q

what is the equation for force, weight, mass?

A

force = mass * acceleration
weight = mass * gravitational acceleration
mass = weight / gravitational acceleration

215
Q

what is a resultant force?

A

when two or more forces act at the same time

216
Q

how do 2 of the 4 fundamental forces come about?

A

aerodynamic loading

217
Q

what happens when vertical and horizontal forces are applied?

A

resultant acts diognally

218
Q

lift always acts in what direction to relative flow?

A

force of lift always acts perpendicular

219
Q

drag aways acts in what direction to the relative wind?

A

parallel and in the same direction

220
Q

as the AOA moves forward what happens to the vector?

A

it leans forward creating a different lift/drag ratio

221
Q

what does the overall aerodynamic force acting on the wing do?

A

provides a resultant force on the wing

222
Q

what happens when static pressure increases?

A

dynamic pressure decreases

223
Q

what is ambient pressure?

A

undisturbed air at room temp

224
Q

what is static pressure?

A

inversely proportional to dynamic pressure

225
Q

what is pressure distribution caused by?

A

variation of local static and dynamic pressure on a surface

226
Q

what relationship does Bernoulli’s printable show?

A

between pressure and velocity

227
Q

when there is a positive AOA is used where does the upwash and downwash happen at?

A

upwash above the stagnation point
downwash on the trailing edge

228
Q

what is pressure difference related to?

A

related to the difference in relative air speeds on the two surfaces

229
Q

the velocity of distribution around an airfoil can be broken into two components what are they?

A

mean value components
circulatory components

230
Q

the faster the flight speed what is needed less?

A

less circulation required to generate lift

231
Q

what determines pressure distribution around what?

A

shape of profile and AOA determines pressure distribution around airfoil for coefficient of lift and drag

232
Q

surface area is proportional to what?

A

lift generated

233
Q

the surface area and its condition will influence what?

A

the amount of lift produced

234
Q

what does the magnitude of pressure distribution on an airfoil depends on what?

A

energy of the airflow

235
Q

aerodynamic forces can be represented by what?

A

dynamic pressure
surface area of profile
shape of profile
AOA

236
Q

what is the equation for dynamic pressure?

A

= 1/2 * density * velocity^2

237
Q

what is the most important variable for lift and drag?

A

airstream velocity which combines with airstream density determines dynamic pressure

238
Q

can we calculate actual lift in flight?

A

no a wind tunnel is needed

239
Q

what scale measures drag in actual lift?

A

horizontal scale

240
Q

what scale measures lift in actual lift?

A

vertical scale

241
Q

what is the equation for coefficient of lift?

A

measured lift / theoretical lift

242
Q

what is the equation for coefficient of drag?

A

measured drag / theoretical drag

243
Q

what happens when there is a higher angle of attack?

A

the higher the lift so the more drag so the more turbulent flow

244
Q

what happens when there is a thick profile of the wing?

A

the higher the lift

245
Q

what happens when there is a thick chord of the wing?

A

the higher the lift

246
Q

what does the polar diagram show?

A

that lift and drag coefficients can be combined info on performance of profiles on center of lift and drag for AOA

247
Q

lift drag ratio is plotted against what?

A

against the angle of attack

248
Q

lift to drag ratio is the same as what?

A

as the lift coefficient to drag coefficient

249
Q

what does the polar diagram show for lift and drag?

A

maximum lit and drag ratio

250
Q

what is stall?

A

sudden reduction in lift when critical AOA is reached

251
Q

what happens when AOA increases?

A

flow separation increases which reduces lift

252
Q

what may a fixed wing aircraft experience during stall?

A

a change in altitude

253
Q

what is the angle to relative wind for steady flow, stall point / maximum lift, separated flow?

A

6 degrease for steady flow
15 degrease for stall point / max lift
25 degrease for steady flow

254
Q

where is the stall point?

A

25 degrease due to flow separation

255
Q

where does wing root stall occur?

A

at the root

256
Q

due to wing root stall what happens to the center of gravity?

A

it moves forward

257
Q

during root wing stall where does the stall go?

A

root to tip

258
Q

what happens to the nose when there is a root wing stall?

A

nose pitched down

259
Q

what happens when the nose pitches down due to root wing stall?

A

aircraft loses stall rapidly
airspeed increases
AOA decreases

260
Q

during wing tip stall what input is needed?

A

crew input required to keep aircraft under control

261
Q

what happens to the pitch during wing tip stall?

A

aircraft pitches up
AOA increases
stall conditions increase

262
Q

what happens to center of lift when wing tips stall?

A

it moves towards the lift and forward of the center of gravity

263
Q

what stall makes flow separation more dangerous?

A

wing tip stall is more dangerous

264
Q

what are the ways to protect wing tip stalls include side effects?

A

stall strips but degrease lift
use of slats
use of slots

265
Q

what happens when slots open up?

A

the boundary layer is energized preventing flow separation at the tip

266
Q

where are slats located?

A

on the LE at the wing tip

267
Q

what aircraft are slats used on?

A

on lighter aircraft

268
Q

slats normally do what?

A

extend

269
Q

what happens when slots open up?

A

boundary layer is re energized witch prevents flow separation

270
Q

what can affect the performance of an airfoil?

A

formation of snow and ice
accumulation of dirt and bird droppings

271
Q

what can the build up of ice do?

A

negatively effect weight and drag cause a loss of list and frieze or imbalance of the control surfaces

272
Q

when flying at temps bellow freezing point what happens?

A

ice can form on the tip

273
Q

what flights are ice formations dangerous for?

A

for low speed flights

274
Q

what can upper surface frost cause?

A

reduce the coefficient of lift and critical AOA

275
Q

what will determine the type of ice formed?

A

the type of atmospheric conditions

276
Q

what are the three types of ice?

A

frost, rime and clear

277
Q

what happens if ice is not removed?

A

it can affect laminar flow flow of the aircraft over the LE and cause dangerous loss of lift during takeoff and affect control surfaces

278
Q

the build up of snow and ice can do what?

A

increases the weight and shape on the object on which had formed

279
Q

when will frost form?

A

when aircraft is sat overnight
when it goes from sub zero to moist walm air

280
Q

when does rime ice form?

A

when super cold water droplets freeze on a surface that is bellow freezing temps

281
Q

where can rime ice form?

A

engine inlet
leading edges

282
Q

what is considered the most dangerous ice?

A

clear ice

283
Q

what happens when clear ice forms?

A

happens in large amounts which can damage rear mounted engines

284
Q

describe clear ice?

A

heavy coating of glossy ice
from large supercooled water droplets

Mod 8 basic aerodynamics (4 decks)

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