TOF

1. PRINCIPLES OF AERODYNAMICS THEORY OF FLIGHT
C&G L2 UNIT 201 LO 1 – THEORY OF FLIGHT AND PRIMARY CONTROLS
1
Mark Wootton MA 20
Sep 22

2. RANGE & WELCOME
 Instructor: Mark Wootton MA
 Heath & Safety: trip wires
 Encourage taking notes for any assignment or self study
 15 Min’s (Q&A dependent)
 Homework’s would normally be part of the learning
program
 Post lesson Questions
2

3. AIRCRAFT FLIGHT PRINCIPLES AND PRACTICE LEARNING OBJECTIVES
o Introduction of Teacher to group
o Health and safety (during class activities)
o Behaviours and expectations
o Overview of module and requirements
o Intro to students with one-on-one chats as required
o Computer simulations and animations
o General induction and an introduction to the unit / performance criteria
o External exam pre study
o Review the Learning Plan
o College has Learning and Support for those that feel they need it… please discuss ‘one on one’ as required
3
INTRODUCTIONS MEET THE TEAM…. MEET THE STUDENTS

4.  Assessment method
– external exam
 Multiple choice
 60 questions
 Minimum 33 for pass
AERODYNAMICS AND THEORY OF FLIGHT

5. AERODYNAMICS AND THEORY OF FLIGHT
 Know the nature of airflow around aerodynamic bodies
 Know the characteristics of the basic wing planform
 Know the forces acting on an aircraft in flight
 Understand basic aircraft control using primary control
surfaces

6. Learning Objective
Understand basic fluid control
● Know about how fluid moves around different bodies
● Know about how lift is generated from basic wing planform
6

7. Bernoulli’s Principle
7
• The fact that a pressure drop
accompanies an increased flow velocity
is fundamental to the laws of fluid
dynamics.
• Swiss mathematician, Daniel Bernoulli,
derived the interrelationship between
pressure, velocity and other physical
properties of fluid in 1738.
• Classically, his theorem is used in the
design of aircraft wings to create lift
from the flow of air over the wing
profile.
The Swiss mathematician
and physicist Daniel
Bernoulli (1700-1782) is best
known for his work on
hydrodynamics, but he also
did pioneering work on the
kinetic theory of gases.

8. THE VENTURI PRINCIPLE: NATURE OF FLOW THROUGH A VENTURI TUBE.
8
A venturi creates a constriction within
a pipe (classically an hourglass shape) that
varies the flow characteristics of a fluid
(either liquid or gas)
travelling through the tube.
As the fluid velocity in the throat is
increased there is a consequential
drop in pressure.
Italian scientist Giovanni
B Venturi (1746-1822)
was the first to observe
this phenomenon.

9. NATURE OF SUBSONIC FLOW: ENTRAINMENT
 People have long put the venturi principle to work by using
reduced pressure in high-velocity fluids to move things about.
 With a higher pressure on the outside, the high-velocity fluid
forces other fluids into the stream. This process is
called entrainment.

10. NATURE OF SUBSONIC FLOW: VELOCITY AND PRESSURE
 Relationship of
velocity change
on pressure
happens when
vehicles overtake
each other

11. https://en.wikipedia.org/wiki/Venturi_effect
NATURE OF FLOW THROUGH A RESTRICTED TUBE

12. Bernoulli’s Principle
12
• Bernoulli’s theorem implies, therefore, that if the fluid
flows horizontally so that no change in gravitational
potential energy occurs, then a decrease in fluid pressure
is associated with an increase in fluid velocity.

13. BERNOULLI’S PRINCIPLE AND THE NATURE OF FLUID FLOW

14. BERNOULLI’S PRINCIPLE AND THE NATURE OF FLUID FLOW

15. FLOW OVER AEROFOIL

16. NATURE OF SUBSONIC FLOW: OBJECTS
https://www.pilotwings.org/laminar-
flow.html

17. VENTURI PRINCIPLE AND THE NATURE OF FLOW DEMONSTRATION

18. • Therefore, Bernoulli's principle can then be
used for changes in Velocity and Pressure
calculations
P + ½ ρv2 + ρgh + = constant
P = Pressure
ρ = Fluid Density
V = Velocity
g = Acceleration due to gravity
h = Height
If no change in height: P + ½ρv2 =
constant
Bernoulli’s Principle: Recap
19

19. LIFT FACTOID OF REALITY: QUICK REVIEW OF FORCES (RECAP)
21
Black Staged Markers
showing speed over
the top of the wing in
relation to the speed
of the lower
https://en.wikipedia.org/wiki/File:Karman_trefftz.gif

20. NATURE OF SUBSONIC FLOW
http://processprinciples.com/2012/04/subsonic-lift/

21. AIRFLOW AND AERODYNAMICS
https://www.grc.nasa.gov/www/k-12/airplane/incline.html

22. CENTRE OF LIFT
http://www.aviation-history.com/theory/relative_wind.htm

23. AERODYNAMICS AND THEORY OF FLIGHT
 Know the nature of airflow around aerodynamic bodies
 Know the characteristics of the basic wing planform
 Know the forces acting on an aircraft in flight
 Understand basic aircraft control using primary control
surfaces

24. PRINCIPLES OF AERODYNAMICS THEORY OF FLIGHT
C&G L2 UNIT 202 LO 1 – THEORY OF FLIGHT AND PRIMARY CONTROLS
41
Mark Wootton MA 20
Sep 22

25. Learning Objective
Understand basic aircraft control using primary control surfaces
● Describe the operation and effect of the primary aircraft control surfaces; describe how elevators, ailerons, and rudders
support control about the aircraft axes
● Know about control in roll, pitch, and yaw; describe manoeuvring about lateral, longitudinal and normal axes
42

26. The Main Four Forces in Flight
• Lift force: Lift is a
mechanical force. It is generated
by the interaction and contact of
a solid body with a fluid (liquid or
gas).
• Drag force: Drag is the force that
acts opposite to the direction of
motion. Drag is caused by friction
and differences in air pressure.

27. • Thrust force: Thrust is a
mechanical force generated by
the engines to move the aircraft
through the air .
• Weight force: is the force
generated by the gravitational
attraction of the earth on the
airplane.
The Main Four Forces in Flight

28. MOMENT AND COUPLE
 PHET
Simulation
Balancing Act
 Consolidation

29. FORCES ACTING IN FLIGHT

30. FLIGHT CONTROLS SECONDARY CONTROL SYSTEMS
 Aircraft flight control systems
consist of:
 Primary: the ailerons, elevator (or
stabilator), and rudder constitute the
primary control system and are
required to control an aircraft safely
during flight
48

31. FLIGHT CONTROLS: SECONDARY CONTROL SYSTEMS
 Aircraft flight
control systems
consist of:
 Secondary:
Flaps, Slats,
Spoilers (Air
brakes) & Tabs
49

32. PRIMARY FLIGHT CONTROLS AXIS
 Aircraft flight control s.
The ailerons, elevator (or
stabilator), and rudder
constitute the
primary control system
and are required to
control an aircraft safely
during flight
 These create rotation
around the aircraft axis’
50

33. ELEVATORS
 The elevator is a moveable part of the
horizontal stabilizer, hinged to the back of
the fixed part of the horizontal tail.
 The elevators move up and down together.
When the pilot pulls the stick backward, the
elevators go up.
 Pushing the stick forward causes the
elevators to go down. Lowered elevators
push up on the tail and cause the nose to
pitch down.
 This makes the wings fly at a higher angle
of attack, which generates more lift and
more drag.
51

34. ELEVATORS
52

35. AILERONS
 The ailerons primarily control roll. Whenever lift is increased, induced drag is
also increased.
 When the stick is moved left to roll the aircraft to the left, the right aileron is
lowered which increases lift on the right wing and therefore increases induced
drag on the right wing.
53

36. AILERONS
 Forces exerted
by the
ailerons
54

37. ACTIVE AND PASSIVE CONTROLS
55
A passive sidestick only provides back pressure forces when it is deflected, by
mechanical phenomena such as springs, dampers, and friction. It is passive in that it
cannot be made to move other than by pushing against it, it never moves by itself.
An active side stick has some element installed that enables movement of the stick
other than by hand force: a motor for instance. This is technology that has been
applied for over half a century in flight simulators.
The side sticks in the Cirrus SR22 are active side sticks, they are coupled directly to
elevators and aileron and provide direct feedback of the aero forces.
The future

38. ACTIVE AND PASSIVE CONTROLS
56
The future

39. AILERONS: ADVERSE YAW
 Using ailerons causes adverse yaw,
meaning the nose of the aircraft yaws in a
direction opposite to the aileron
application.
 When moving the stick to the right to
bank the wings, adverse yaw moves the
nose of the aircraft to the left
 Adverse yaw is more pronounced for light
aircraft with long wings, such as gliders.
57
Knowing this how can this be corrected by the pilot?

40. AILERONS: ADVERSE YAW CORRECTION
 It is counteracted by the pilot
with the rudder.
 Differential ailerons are ailerons
which have been rigged such
that the down-going aileron
deflects less than the upward-
moving one, reducing adverse
yaw.
58

41. DIFFERENTIAL AILERONS: AUTOMATIC ADVERSE YAW CORRECTION
 Differential ailerons are ailerons
which have been rigged such
that the down-going aileron
deflects less than the upward-
moving one, reducing adverse
yaw.
59

42. DIFFERENTIAL & FRISE AILERONS: AUTOMATIC ADVERSE YAW CORRECTION
60

43. RUDDER
 The rudder is a fundamental control surface which is typically controlled by pedals
rather than at the stick. It is the primary means of controlling yaw - the rotation of
an airplane about its vertical axis. The rudder may also be called upon to counter-
act the adverse yaw produced by the roll-control surfaces.
61
Primary Controls Recap

44. AIRCRAFT AXIS
 These three axes, referred to as
longitudinal, lateral and vertical,
are each perpendicular to the
others and intersect at
the aircraft centre of gravity.
 Motion around the
longitudinal axis, the
lateral axis and the vertical axis are
referred to as roll, pitch and yaw
respectively
62
AXIS OF CONTROL

45. ROLL, PITCH & YAW
 Imagine three lines running through an airplane and intersecting at
right angles at the airplane's centre of gravity. Rotation around the
front-to-back axis is called roll. Rotation around the side-to-side axis
is called pitch. Rotation around the vertical axis is called yaw.
63
AXIS OF CONTROL

46. RECAP :
 How is lift generated over a simple aerofoil?
 What theory explains variance of pressure with velocity?
 Can you give me an everyday example of Bernoulli at
work?
 Can tell me the four main forces on an aircraft in flight?
 Can you explain why a downward aileron produces
more lift?
 What primary control rotates the aircraft around the
lateral axis? 64

47. Learning Objective
Understand basic fluid characteristics:
● Know about how fluid moves around different bodies
● Know about how lift is generated from basic wing planform
Understand basic aircraft control using primary control surfaces
● Describe the operation and effect of the primary aircraft control surfaces; describe how
elevators, ailerons, and rudders support control about the aircraft axes
● Know about control in roll, pitch, and yaw; describe manoeuvring about lateral,
longitudinal and normal axes
67

48. NATURE OF SUBSONIC FLOW
 When the speed of the object is well
below the speed of the sound, density
of the air around the object will remain
same
 At higher speed, density will change
because of the compressibility, hence
the forces acting on the object
https://www.grc.nasa.gov/www/k-12/rocket/mach.html
68

49. NATURE OF SUBSONIC FLOW
 Change of airspeed around the
aerofoil
 If the air speed goes up, flow
become turbulent
https://en.wikipedia.org/wiki/Mach_number
69

50. NATURE OF SUBSONIC FLOW
 Subsonic flow
 Incompressible flow (density in constant)
 Bernoulli’s equation can be applied
 𝜌𝑔ℎ +
1
2
𝜌𝑣2 + 𝑝 = 𝑐𝑜𝑛𝑠𝑡𝑎𝑛𝑡
 Energy of steady steam 𝑝 +
1
2
𝜌𝑣2 = 𝑐𝑜𝑛𝑠𝑡𝑎𝑛𝑡
http://processprinciples.com/2012/04/subsonic-lift/
70

51. NATURE OF SUBSONIC FLOW
 Streamline is a path of moving
particle in the fluid flow
 Velocity is tangent at each point
 Streamline never cross
 Bernoulli's equation can be applied
along a streamline
https://www.grc.nasa.gov/www/k-
12/VirtualAero/BottleRocket/airplane/stream.html
71

52. NATURE OF SUBSONIC FLOW
https://www.pilotwings.org/laminar-
flow.html
72

53. NATURE OF SUBSONIC FLOW
http://processprinciples.com/2012/04/subsonic-lift/
73

54. NATURE OF SUBSONIC FLOW
http://web.mit.edu/13.021/13021_2003/Lifting%20surfaces/lectureB_files/image004.gif
74

55. NATURE OF SUPERSONIC FLOW
https://en.wikipedia.org/wiki/Mach_number
75

56. NATURE OF SUBSONIC FLOW
 What is the speed of
the sound?
 What is the density of
air at the sea level?
https://www.grc.nasa.gov/www/k-12/rocket/mach.html
76

57. NATURE OF TRANSONIC FLOW
 What is the speed of the transonic
flight?
 In m/s
 km/h
 mph
https://www.grc.nasa.gov/www/k-12/rocket/mach.html
77

58. NATURE OF HYPERSONIC FLOW
 What is the minimum speed of the
hypersonic flight?
 In m/s
 km/h
 mph
https://www.grc.nasa.gov/www/k-12/rocket/mach.html
These things don't happen at one particular speed, so the term
"hypersonic" instead refers to the point at which they start to
meaningfully affect the mechanics of flight—generally accepted to be
Mach 5, 1715 m/s, 6174 km/hr , 3836.35 mph, conditions of 20 degrees
Celsius at sea level.
78

59. NATURE OF SUBSONIC FLOW
 Useful videos – Airflow around the airfoil
 Upper and lower speed explanation
 Proof of flow
 Wingtip vorticies
 Solving Vortice problems
 Other Vortice effects
79

60. AEROFOIL TERMINOLOGY
 Angle of attack and angle of incident
 Washout and Stall
80

61. TERMINOLOGY
 Wing Area
 Span
 Root Chord
 Tip Chord
81

62. AEROFOIL TERMINOLOGY
 Cross sectional
view of the wing
https://www.rcgroups.com/forums/showatt.php?attachmentid=33911
60
82

63. FLOW OVER AEROFOIL
http://nptel.ac.in/courses/101103004/module5/lec7/2.html
83

64. AEROFOIL TERMINOLOGY
https://www.rcgroups.com/forums/showatt.php?attachmentid=33911
60
85

65. AEROFOIL TERMINOLOGY
 Taper Ratio (λ)
• The wing taper ratio can be
calculated as the ratio of tip chord
to root chord, The mean
aerodynamic chord can be found by
integrating the individual section
chords across the span. The aircraft
generates lift by moving quickly
through the air.
86

66. AEROFOIL TERMINOLOGY
 Thickness to Chord Ratio =
𝑡
𝑐
https://www.grc.nasa.gov/www/k-12/airplane/geom.html
87

67. AEROFOIL TERMINOLOGY
http://www.ksu.lt/wp-content/uploads/2017/06/M8-Selected-pages-Basic-
Aerodynamics.pdf
90

68. AEROFOIL TERMINOLOGY
http://www.ksu.lt/wp-content/uploads/2017/06/M8-Selected-pages-Basic-
Aerodynamics.pdf
91

69. VISCOSITY EFFECTS
 Viscosity effect
and the boundary
layer
https://www.grc.nasa.gov/www/k-12/airplane/boundlay.html
92

70. VISCOSITY EFFECTS
 Viscosity effect
and the boundary
layer
http://aviation_dictionary.enacademic.com/6897/transition_point
93

71. CENTRE OF LIFT
http://www.aviation-history.com/theory/relative_wind.htm
94

72. FLOW OVER AEROFOIL
https://ecoursesonline.icar.gov.in/mod/page/view.php?id=1080
95

73. FLOW OVER AEROFOIL
https://ecoursesonline.icar.gov.in/mod/page/view.php?id=1080
96

74. AIRFLOW AND AERODYNAMICS
https://www.grc.nasa.gov/www/k-12/airplane/incline.html
97

75. AIRFLOW AND AERODYNAMICS
http://aerospaceengineeringblog.com/boundary-layer-separation-and-pressure-drag/
98

76. AIRFLOW AND AERODYNAMICS
http://nptel.ac.in/courses/101103004/module5/lec7/2.html
99

77. PRINCIPLES OF AERODYNAMICS THEORY OF FLIGHT
C&G L2 UNIT 101 LO 1 – THEORY OF FLIGHT AND PRIMARY CONTROLS
100
Mark Wootton MA 05
Oct 22

78. AIRFLOW AND AERODYNAMICS
 https://www.youtube.com/watch?time_continue=4&v=WFcW5-
1NP60
101

79. TYPES OF DRAG
 Parasite Drag– This drag is further broken down
 Form drag
 Skin Friction
 Induced Drag
Transport Canada Study and Reference Guide Glider Pilot FTGU pages 91-
98
102

80. PARASITE DRAG
http://learntoflyblog.com/wp-content/uploads/2014/08/2-15.png
103

81. PARASITE DRAG
 Drag of all those parts the airplane which DO NOT contribute to lift
 This drag is hard to eliminate but it can be minimized
 Form drag is caused by the shape of the aircraft
 Landing gear
 Antennas
 Struts
 Wing tip fuel tanks
Transport Canada Study and Reference Guide Glider Pilot FTGU pages 91-
98
104

82. PARASITE DRAG
 Skin Friction
 The tendency of air flowing over the body to cling to its
surface
 What causes it to resist motion?
 Ice on the wings
 Dirt build up
Transport Canada Study and Reference Guide Glider Pilot FTGU pages 91-
98
105

83. INDUCED DRAG
 Caused by those parts of
an airplane which are
active in producing lift
 Cannot be eliminated
https://www.pilotwings.org/induced-drag.html
Transport Canada Study and Reference Guide Glider Pilot FTGU pages 91-
98
106

84. INDUCED DRAG
https://www.pilotwings.org/induced-drag.html
107

85. INDUCED DRAG
 The less drag you have…
 Flying a glider: the further you can fly
 Flying an airplane: the less fuel you use
 Therefore streamlining is important
 A design device by which a body is shaped to minimize drag
Transport Canada Study and Reference Guide Glider Pilot FTGU pages 91-
98
108

86. TOTAL DRAG
https://aviation.stackexchange.com/questions/13885/whats-the-advantage-of-using-short-wings-rather-than-long-
wings
109

87. SPEED OF SOUND
 The speed of sound is the distance
travelled per unit time by
a sound wave as it propagates
through an elastic medium.
 At 20 °C (68 °F), the speed of
sound in air is about 343 metres
per second (1,235 km/h; 1,125 ft/s;
767 mph; 667 kn), or a kilometre in
2.9 s or a mile in 4.7 s.
146

88. EFFECT ON SPEED OF
SOUND
 At higher altitudes, the air density is lower than at
sea level. ... Because the speed of sound increases
with air temperature, and air temperature generally
decreases with altitude, the true airspeed for a
given Mach number generally decreases
with altitude.
147

89. ISA – SPEED OF SOUND TEMPERATURE COMPARISON
148
The speed of sound mimics
(and is used in calculations)
with the Temperature
variance in the different
spheres
The speed of sound increases
with height in two regions of
the stratosphere and
thermosphere, due to heating
effects in these regions.
SOS in air

90. ISA – SPEED OF SOUND TEMPERATURE COMPARISON
149

91. SUBSONIC FLIGHT
 Flight that is below
the speed of sound
150
SUBSONIC FLIGHT?

92. TRANSONIC FLIGHT
 In aeronautics,
transonic flight is
flying at or near the
speed of sound 343
metres per second,
relative to the air
through which the
vehicle is traveling
151

93. SUPERSONIC FLIGHT?
Supersonic flight is
flight faster than the
speed of sound
(Mach number 1)
152
SOS = 343 m/s

94. HYPERSONIC FLIGHT?
Aircraft speeds which are much
greater than the speed of
sound, the aircraft is said to
be hypersonic.
Typical speeds for hypersonic
aircraft are greater than 3000
mph and Mach number M
greater than five, M > 5
153
Future Development
Designs on offer
SOS = 343 m/s

95. COMPARISONS OF SPEED
154
The Insane
Engineering of
the SR-71
Blackbird
1976
3.6 Mach

96. FASTEST AIRCRAFT?
155
Was the fastest (rocket-) plane in the World – X-15 (1967)
It reached altitudes
higher than 100
kilometres, speeds
higher than Mach 6
SOS = 343 m/s

97. FASTEST AIRCRAFT?
156
It's Official.
Guinness World Records recognized
NASA's X-43A scramjet with a new world
speed record for a jet-powered aircraft -
Mach 9.6, or nearly 7,000 mph
NASA's X-43A scramjet
The X-43A set the new mark and broke its own world
record on its third and final flight on Nov. 16, 2004.
The SR-72 - The Successor to the SR-71 Blackbird
SOS = 343 m/s

98. MACH
NUMBER
 The ratio of the speed of a
body to the speed of
sound in the surrounding
medium.
 It is often used with a
numeral (as Mach 1, Mach
2, etc.) to indicate the
speed of sound, twice the
speed of sound, etc.
157
MACH NUMBER

99. CRITICAL MACH NUMBER
 In aerodynamics, the critical
Mach number (Mcr or M* ) of
an aircraft is the lowest Mach
number at which the airflow
over some point of the
aircraft reaches the speed of
sound, but does not exceed
it.
158

100. SHOCKWAVE
 When an airplane travels less than the
speed of sound, the air ahead of it actually
begins to flow out of the way before the
plane reaches it. The pressure waves
created by the airplane passing through
the air end up being smooth and gradual.
 But as an airplane reaches the speed of
sound and catches up to its own pressure
waves, the air ahead of it receives no
warning of the plane’s approach.
 The airplane plows through the air,
creating a shock wave. As air flows
through the shock wave, its pressure,
density, and temperature all increase—
sharply and abruptly.
159

101. SHOCKWAVE
160

102.  Transonic buffet is caused by the separated turbulent boundary layer
striking the airframe (horizontal stabilizer, wings, fuselage) with considerable
force causing a high amplitude vibration, which physically shakes the whole
aircraft.
161
TRANSONIC BUFFET

103. DRAG
 and the flow does that by
going through a shock
wave (an abrupt reduction
in speed and a
corresponding abrupt
increase in pressure).
 That shock wave occurs in
contact with the body and
messes up the boundary
layer (causes flow
separation). That strongly
separated boundary layer
is what causes the huge
increase in drag. 162
Drag is relatively high near Mach 1 because in the flow field
around the body, there are still local regions towards the
back part of the body where the flow goes back to being
subsonic (M<1)

104. CONTROL REVERSAL
 the problem occurs when the
amount of airflow over the wing
becomes great enough that the
force generated by the ailerons is
enough to twist the wing itself, due
to insufficient torsional stiffness of
the wing structure.
 For instance when the aileron is
deflected upwards in order to make
that wing move down, the wing
twists in the opposite direction. The
net result is that the airflow is
directed down instead of up and the
wing moves upward, opposite of
163

105. TUCK UNDER
 Mach tuck is an aerodynamic effect whereby the nose of an aircraft tends to pitch downward as the
airflow around the wing reaches supersonic speeds. This diving tendency is also known as "tuck under"
164
https://www.boldmethod.
com/blog/lists/2019/05/
mach-tuck-explained-in-
eight-steps/

106. SUPERSONIC INTAKE
 The inlet lip is sharpened to
minimize the performance losses
from shock waves that occur
during supersonic flight.
 For a supersonic aircraft, the inlet
must slow the flow down to
subsonic speeds before the air
reaches the compressor.
165

107. 166

108. FINALLY: THE PAPER PLANE THEORY
Arghhh the explanation?
181

109. SECONDARY CONTROLS
204

110. AIRCRAFT AXIS
 These three axes, referred to as
longitudinal, lateral and vertical,
are each perpendicular to the
others and intersect at
the aircraft centre of gravity.
 Motion around the
longitudinal axis, the
lateral axis and the vertical axis are
referred to as roll, pitch and yaw
respectively
206
AXIS OF CONTROL

111. LOAD FACTOR
• The load factor is the ratio of the aerodynamic force on the aircraft to
the gross weight of the aircraft (e.g., lift/weight).
• For example, a load factor of 3 means the total load on an aircraft’s
structure is three times its gross weight. When designing an aircraft, it
is necessary to determine the highest load factors that can be
expected in normal operation under various operational situations.
• These “highest” load factors are called “limit load factors.”
207

112. LOAD FACTOR
208

113. • Supplementary information to illustrate the
significance of the V-n diagram. The lines of
maximum lift capability are the first points of
importance on the V-n diagram.
• The subject aircraft is capable of developing
no more than one positive "g" at 100 knots,
the wing level stall speed of the airplane.
Since the maximum load factor varies with
the square of the airspeed, the maximum
positive lift capability of this airplane is 2 g
at 100 knots, 4 g at 200 knots, 7.5 g at 400
knots.
• Any load factor above this line is unavailable
aerodynamically, i.e., the subject airplane
cannot fly above the line of maximum lift
capability.
LOAD FACTOR
211

114. • The flight operating strength of an airplane is
presented on a graph whose horizontal scale is
airspeed (V) and vertical scale is load factor (n).
• The presentation of the airplane strength is
contingent on four factors being known:
• the aircraft gross weight,
• the configuration of the aircraft (clean,
external stores, flaps, and landing gear
position, etc.),
• symmetry of loading (since a rolling pull out
at high speed can reduce the structural
limits to approximately two-thirds of the
symmetrical load limits), and
• the applicable altitude.
LOAD FACTOR
• A change in any one of these four factors can cause important changes to operating
212

115. LOAD FACTOR
213

116. LOAD FACTOR
214

117. Why Does Stall Speed Increase With Bank Angle?
AIRCRAFT STABILITY Stall and banking
AoA needs to increase
maintain altitude at
reduced lift vector on
banking aircraft
222

118. Why Does Stall Speed Increase With Bank Angle?
AIRCRAFT STABILITY Stall and banking
Load factor is measured in Gs.
• So if your load factor in a
turn is 2 Gs,
• You feel twice as heavy as
you really are (and your
arms want to flop down to
your seat).
223

119. Why Does Stall Speed Increase With Bank Angle?
AIRCRAFT STABILITY Stall and banking
• The same goes for your
airplane - it 'feels' twice as
heavy.
• But what does load factor
have to do with stall speed?
• Stall speed increases in
proportion to the square
root of load factor. 224

120. Why Does Stall Speed Increase With Bank Angle?
AIRCRAFT STABILITY Stall and banking
Stall speed increases (the
point of stall) in proportion to
the square root of load factor.
https://www.boldmethod.com/bl
og/video/2015/03/pilot-skims-
the-water-in-air-race/
225

121. SOW Where we are!
AC 4.3 Explain the influence of load factor on aerodynamic performance
● Define load factor and explain its effect on lift generated; state how load factor changes alter the aircraft’s
flight characteristics
● Explain the term ‘flight envelope’; explain flight envelope in terms of the loading analysis to which the
aircraft design must comply; describe the dependency of the flight envelope on:
• aircraft gross weight
• configuration of the aircraft (cleanliness, external stores)
• position of flaps
• position of landing gear
• symmetry of loading
• altitude
226

122. Why Does LOAD FACTOR Increase With Bank Angle?
AIRCRAFT STABILITY Stall and banking
Stall speed
increases in
proportion to the
square root of
load factor.
https://www.youtube.com/wat
ch?v=3l6gxlQbbjU
227

123. Symmetry?
AIRCRAFT STABILITY Stall and banking
Asymmetric Loads And Manoeuvring Stalls
That’s asymmetric loading, and the rising wing will stall
first, because it will reach its critical AoA earlier than the
other one.
The structure will survive only if the maximum g
experienced by any part of the airframe is less than the
load limit.
In other words, placing maximum loading on an
airframe—by pulling out of a dive, for
example—should only be done with the
wings level. Bundesarchiv BV 141
228

124. SOW Where we are!
● Know about flight force, including couples (lift/weight and thrust/drag), action about centre of gravity (C of G)
and centre of pressure (CoP);
• describe stable, unstable and neutrally stable states of equilibrium;
• understand diagrams that use force vectors to show the different states
• explain the nature of aircraft flight stability
• stability: definitions for static, dynamic and passive stability around the longitudinal, lateral and
directional axis
229

125. AIRCRAFT CENTRE OF GRAVITY
• The centre of gravity is the
average location of the weight
of the aircraft.
• The weight is actually
distributed throughout the
airplane, and for some problems
it is important to know the
distribution. But for total aircraft
manoeuvring, we need to be
concerned with only the total
weight and the location of the
centre of gravity. 230

126. MOMENT AND COUPLE
Covered in Feb 21 231

127. • Aircraft Stability is the tendency of an aircraft to return to its original position
when it's disturbed.
AIRCRAFT STABILITY
232

128. • Aircraft Stability is the tendency of an aircraft to return to its original position
when it's disturbed.
AIRCRAFT STABILITY
What is the aircraft built for?
Stable aircraft, like Cessna and Piper training aircraft, are built to be
statically and dynamically stable, making them easy to trim and fly
'hands off’.
However, jets like the F-16, are built to be unstable, making them
highly manoeuvrable and easy to pitch, roll and yaw aggressively. 233

129. SOW Where we are!
Know the different types of stability, including
• short period pitch oscillation
• long period pitch oscillation (phugoid)
• Dutch roll
• Weather cocking
Know the differences between statically stable, unstable and neutral aircraft, including:
• static and positive stability
• negative stability (unstable)
• zero stability (neutral)
describe how banking of an aircraft is used to balance the centripetal force and component of lift in a constant
radius turn (static stab and control)
234

130. • A long period oscillation of aircraft motion in which the aircraft pitches up and
climbs, and then pitches down and descends, accompanied by speeding up and
slowing down as it goes ‘downhill’ and ‘uphill’.
• This is one of the basic flight dynamics modes of an aircraft
AIRCRAFT STABILITY: A phugoid or fugoid
235

131. • Shorter period mode is called simply the ‘short-period mode’. The short-period
mode is a usually heavily damped oscillation with a period of only a few seconds.
• The motion is a rapid pitching of the aircraft about the centre of gravity, essentially
an angle-of-attack variation. The time to damp the amplitude to one-half of its
value is usually on the order of 1 second. Ability to quickly self damp when the
stick is briefly displaced is one of the many criteria for general aircraft certification.
AIRCRAFT STABILITY: A short Oscillation
236

132. AIRCRAFT STABILITY: Dutch Roll
237
Dutch roll is a type of aircraft motion, consisting of an
out-of-phase combination of "tail-wagging" (yaw) and
rocking from side to side (roll). This yaw-roll coupling is
one of the basic flight dynamic modes
https://www.boldmethod.com/learn-to-fly/aerodynamics/dutch-
roll/
https://www.boldmethod.com/learn-to-fly/aerodynamics/dutch-
roll/
https://aerospaceengineeringblog.com/control-and-stability-of-
aircraft/

133. AIRCRAFT STABILITY: Weather cocking
238
Weather-vaning or weather cocking is a phenomenon
experienced by aircraft on the ground and rotorcraft on the
ground and when hovering.
Aircraft on the ground have a natural pivoting point on an
axis through the main landing gear contact points
[disregarding the effects of toe in/toe out of the main
gear].
As most of the side area of an aircraft will typically be
behind this pivoting point, any crosswind will create
a yawing moment tending to turn the nose of the aircraft
into the wind.
DO NOT confuse with directional stability, as experienced by aircraft in flight.
https://www.youtube.com/watch?v=6CBHHBi1aTw

134. • Static stability is the initial tendency of an aircraft to return to its original position
when it's disturbed. There are three kinds of static stability: positive, negative and
neutral
AIRCRAFT STABILITY
239

135. • understand diagrams that use force vectors to show the different states
Understand Force Vectors
https://www.bbc.co.uk/bitesize/guides/z37jng8/revision/2
https://www.youtube.com/watch?v=4rG9u478X1Q
240

136. SOW Where we are!
LO 4: Understand basic aircraft control using primary control surfaces
AC 4.1 Describe the meaning of ‘aircraft control’
● Describe the operation and effect of the primary aircraft control surfaces; describe how elevators, ailerons, and rudders
support control about the aircraft axes
● Know about control in roll, pitch, and yaw; describe manoeuvring about lateral, longitudinal and normal axes
AC 4.2 Describe typical aircraft performance
● Describe different phases of flight; phases: straight and level flight, climb, descent, glide, turn; describe how
turning flight changes the loading on an airframe; describe how turning flight is related to the stall
241
Check of understanding

137. SOW Where we are!
LO 5: Understand the nature of aircraft stability and control
AC 5.1 Explain stability and control of an aircraft in flight
● Know about flight force, including couples (lift/weight and thrust/drag), action about centre of gravity (C of G)
and centre of pressure (CoP);
• describe stable, unstable and neutrally stable states of equilibrium;
• understand diagrams that use force vectors to show the different states
• explain the nature of aircraft flight stability
• stability: definitions for static, dynamic and passive stability around the longitudinal, lateral and
directional axis
242
10 min break back @ 14.10
Check of understanding

138. SOW Where we are!
LO 5: Understand the nature of aircraft stability and control
AC 5.1 Explain stability and control of an aircraft in flight
Know the different types of stability, including
• short period pitch oscillation
• long period pitch oscillation (phugoid)
• Dutch roll
• Weather cocking
Know the differences between statically stable, unstable and neutral aircraft, including:
• static and positive stability
• negative stability (unstable)
• zero stability (neutral)
describe how banking of an aircraft is used to balance the centripetal force and component of lift in a constant
radius turn (static stab and control)
243
Check of understanding
break back @ 15.30

139. • Static stability is the initial tendency of an aircraft to return to its original position
when it's disturbed. There are three kinds of static stability: positive, negative and
neutral
AIRCRAFT STABILITY
244

140. • Stability is the ability of an aircraft to correct for conditions
that act on it, like turbulence or flight control inputs. For
aircraft, there are two general types of stability: static and
dynamic.
• Static stability is the initial tendency of an aircraft to return
to its original position when it's disturbed. There are three
kinds of static stability: positive, neutral and negative.
• Dynamic stability is how an airplane responds over time to
a disturbance. And there are three kinds of dynamic
stability as well: positive, neutral and negative.
AIRCRAFT STABILITY Check of understanding
245

141. • Dynamic stability is how an airplane responds over time to a disturbance.
And there are three kinds of dynamic stability as well: positive, neutral and
negative.
AIRCRAFT STABILITY : Dynamic
246

142. NEUTRAL STATIC STABILITY
 An aircraft that has
neutral static stability
tends to stay in its new
attitude when it's
disturbed. For example,
if you hit turbulence and
your nose pitches up 5
degrees, and then
immediately after that it
stays at 5 degrees nose
up, your airplane has
neutral static stability.
247
NEUTRAL STATIC STABILITY

143. NEGATIVE STATIC STABILITY
 an aircraft that has negative
static stability tends to
continue moving away from
its original attitude when it's
disturbed. For example, if
you hit turbulence and your
nose pitches up, and then
immediately continues
pitching up, you're airplane
has negative static stability.
For most aircraft, this is a
very undesirable thing.
248
NEGATIVE STATIC STABILITY

144. POSITIVE STATIC STABILITY
 An aircraft that has
positive static stability
tends to return to its
original attitude when it's
disturbed.
 Let's say you're flying an
aircraft, you hit some
turbulence, and the nose
pitches up. Immediately
after that happens, the
nose lowers and returns
to its original attitude.
249
POSITIVE STATIC STABILITY
?

145. NEUTRAL DYNAMIC STABILITY
 Aircraft with neutral
dynamic stability have
oscillations that never
dampen out.
 As you can see in the
diagram below, if you
pitch up a trimmed,
neutrally dynamic stable
aircraft, it will pitch nose
low, then nose high
again, and the
oscillations will
continue, in theory,
forever. 250
NEUTRAL DYNAMIC STABILITY

146. NEGATIVE DYNAMIC STABILITY
 Aircraft with negative
dynamic stability
have oscillations that
get worse over time.
 The diagram below
pretty much sums it
up.
 Over time, the pitch
oscillations get more
and more amplified.
251
NEGATIVE DYNAMIC STABILITY

147. POSITIVE DYNAMIC STABILITY
 Aircraft with positive dynamic stability
have oscillations that dampen out over
time. The Cessna 172 is a great example.
If your 172 is trimmed for level flight,
and you pull back on the yoke then let
go, the nose will immediately start and
pitch down.
 Depending on how much you pitched
up initially, the nose will pitch down
slightly nose low, and then, over time,
pitch nose up again, but less than your
initial control input.
 Over time, the pitching will stop, and
your 172 will be back to its original
attitude.
252
POSITIVE DYNAMIC STABILITY

148. SOW Where we are!
Describe major components on an aircraft that affect stability in flight
● Describe longitudinal static stability, including trim and stability, centre of pressure and aerodynamic centre
movement; describe the effect of the tailplane, the C of G position, and the effect of loading of stores and
cargo
● Describe the balancing aerodynamic force from the tailplane; using the principle of moments, determine
balancing forces needed to maintain aircraft in static equilibrium
● Describe lateral static stability, including yawing stability (yawing motion or weathercocking, use of fin, keel
surface and wing dihedral), rolling stability (use of high wings and sweepback), use of anhedral
● Describe directional stability; describe how the fin (vertical stabiliser) corrects yawing motion, describe
how the keel surface area (including area of fin) behind the C of G affects directional stability
● Describe methods of enhancing stability, including adjusting the centre of gravity, design of lifting and
control surfaces (wings, canards, tailplane) 253

149. CLASS EXERCISE
 Find 3 accidents online (highlight date, any injuries, and main cause in opening paragraph) concerning and referencing any due to:
 Structural failure
 Aircraft loading or overloading
 Flight stability issues
 Aircraft control issues (But concern the narrative to describing the stability issue rather than the technical input issue)
Try to give 3 different examples
Use good main titles, subtitles, graphics and avoid long paragraphs (break them down with subtitles)
Use page numbers and ensure you place Http links at the end of each aircraft incident
Use Spell Checker
254
https://www.icao.int/safety/iStars/Pages/Accident-
Statistics.aspx
https://en.wikipedia.org/wiki/Loss_of_control_(aeronautics)
https://www.aopa.org/-/media/files/aopa/home/pilot-
resources/safety-and-proficiency/accident-
analysis/special-reports/stall_spin.pdf
https://en.wikipedia.org/wiki/List_of_aircraft_structural_fail
ures

150. Any Questions?
https://www.youtube.com/watch?v=lObfaKxqUwA
https://www.youtube.com/watch?v=4a8cntPdRtk
https://www.youtube.com/watch?v=I89EMDZ0dsc

151. OBJECTIVE 5.3
Explain the reason for balancing, including how flutter can occur
and the purpose and methods of mass balance/aerodynamic balance

152. WHAT IS FLUTTER? REASONACE
• Understanding Resonance
Buildings
Testing
Real Time
The Glass

153. WHAT IS FLUTTER?
• Flutter phenomena are seen when vibrations
occurring in an aircraft match the natural
frequency of the structure.
• If they aren’t properly damped, the oscillations
can increase in amplitude, leading to structural
damage or even failure.
• A similar problem occurs in buildings, rotating
masses and bridges i.e. the Tacoma Narrows
Bridge in 1940.
https://www.youtube.com/watch?v=j-zczJXSxnw
The bridge's main span finally collapsed in 40-mile-
per-hour (64 km/h) winds on the morning of
November 7, 1940, as the deck oscillated in an
alternating twisting ...
Design: Suspension
Opened: July 1, 1940
Longest span: 2,800 feet (853.4 m)
Total length: 5,939 feet (1,810.2 m)

154. WHAT IS FLUTTER?
• Aeroelastic effects (in particular flutter) often set limits to the maximum speed
of fixed wing aircraft in each configuration.
• Structural stiffness is normally checked during static and ground resonance
testing.
• A flight flutter investigation is included in the development programme.
• Flutter is a violent, destructive vibration of the aerofoil surfaces, caused by
interaction of their inertia loads, aerodynamic loads and structural stiffness.

155. WHAT IS FLUTTER?
Flutter, and aeroelasticity in general, is
a topic that is often misunderstood or
incorrectly applied due to its inherent
complexity.
To start, let’s first consider what flutter is;
an instability due to an interaction
between aerodynamic, inertial, and
elastic forces.
Composites assist with flex/

156. FLUTTER
Basically, the problem is as follows:
The wing root is fixed to the aircraft fuselage, the wing tip is not fixed and can twist.

157. FLUTTER
2 types
of twist
to
conside
r

158. FLUTTER
• So the wing would like to position itself
perpendicular to free stream - the tipis
twisted by the stream, and stopped by the
torsion stiffness of the wing box
• The torsion stiffness and the damping
need to be sufficiently high to stop the
construction from overshooting, and then
being pulled back and forth in an
oscillation and over bending

159. FLUTTER
Basically, the problem is as follows:
The air streaming over the wing creates lift, but also creates a twisting moment. A longish body
in a fluid stream wants to position itself perpendicular to the stream, that is why we need
empennages.
• The empennage also known as the tail or tail
assembly, is a structure at the rear of an aircraft
that provides stability during flight, in a way similar
to the feathers on an arrow.
• The term derives from the French language verb
empenner which means "to feather an arrow"

160. FLUTTER TEST
A flutter test is performed to determine what speed flutter occurs yet is still damped.
Theoretically an aircraft should be able to stay structurally intact up to the design dive speed (Vd)
which is at least 1.4 times the design cruise speed. In flight tests, the Vd is not always
demonstrated as this is very risky since there would not be any margin from breaking up.
The maximum speed is slowly increased in subsequent flight tests with careful data analyses in
between up to a point where the test team decides that it is no longer safe to continue.
This establishes the maximum demonstrated dive speed (Vdf); the published maximum
operating speed (Vmo) and never-exceed speed (Vne) are well below Vdf to give margin from
disaster.

161. https://www.youtube.com/watch?v=egDWh7jnNic
Examples of sound

163. FIXES
• Because flutter can be analysed, designs can be modified to prevent
flutter before an aircraft is built, tested and flown.
• One design parameter is the maximum air speed. In particular, the ratio
of the energy input to the energy dissipated will depend on the air
speed. A steady oscillation may occur when this ratio is unity
• The air speed for this case is called the 'critical air speed' An aircraft
may have various possible flutter modes. Ideally, the lowest critical
speed exceeds the highest possible flying speed by a reasonable safety
margin

164. FIXES
• When structures incorporate fibre-reinforced composite materials,
design calculations and testing have to take account of additional
environmental factors such as;
• temperature,
• moisture uptake,
• ultraviolet ageing
• and the potential effects of accidental damage

165. FIXES
There are several additional measures to prevent flutter.
• One method is to uncouple the torsion and bending motion by modifying the
mass distribution to move the centre of gravity closer to the centre of twist
• Another method is to increase the stiffness/mass ratios within the structure
• This would increase the natural frequencies
• Note that the energy input per cycle during flutter is nearly independent of
frequency. The energy dissipated per cycle is proportional to frequency.

166. FIXES

167. TESTING
• After the design is analysed the aircraft undergoes
wind tunnel testing and flight-testing to verify the
analysis. Low-speed wind tunnel testing of the full-
span model with scaled stiffness and mass
properties visually identifies instabilities.
• High-speed wind tunnel tests investigate the
transonic flight regime. The models are heavily
instrumented to verify aerodynamic forces and
reactions.

168. TESTING
• One facility used extensively for flutter
clearance testing (which means to
ensure that flutter does not occur
within the envelope of where the
aircraft will fly) is the NASA Langley
Research Centre's Transonic
Dynamics Tunnel (TDT).
• The NASA Langley TDT has provided
a unique capability for aeroelastic
testing for over forty years.

169. TESTING
• Flutter clearance or risk reduction tests are aimed at uncovering potential flutter problems and
identifying potential solutions of a specific design through airplane configuration studies and
tests of various components
• Wind-tunnel models are dynamically and aeroelastically scaled to a
'theoretical' airplane configuration
• The results from these tests are considered experimental research that
contributes to the flutter clearance of the aircraft configuration.
• Finally, flight-testing is performed at many conditions in the flight envelope. The control surfaces
are excited and response characteristics are measured. As speed is incrementally increased,
frequency and damping trends are calculated from the measured responses.
• A successful design exhibits no flutter behaviour in the flight envelope.

170. CLASS EXERCISE: AFTER BREAK @ 11.00 TASK GIVEN
275
Research how designers over come Flutter…
• Identify different types of control design
• Make sure you explain why and how flutter is reduced
• Pictures are a must
• Present as assessment standard

171. Principles of Flight: Axes/Control Surfaces (Grades K-4) (nasa.gov)

172. ASSIGNMENT WORK AND MOCK EXAM
What are the pressures and deadlines?
Revision and assignment catch up today to
relax pressure of submission deadlines
Upload record of work completed to Teams
Folder in Unit 3 for this week

173. THINGS WE TALK ABOUT: LATEST
Aspect Ratio News
Flat spin in loss of thrust

174. OBJECTIVE 5.4 LIFT AUGMENTATION DEVICES AND HOW THEY WORK
Lift Augmentation

175. OBJECTIVE 5.4 LIFT AUGMENTATION DEVICES AND HOW THEY WORK
Slats and Flaps
• A Lift augmentation system is a device installed on the wing of an
aircraft to produce an increase in lift at a given speed
• It can be installed on the leading edge of the wing (‘leading edge slats’)
• or on the trailing edge (‘wing flaps’)
Boeing 727
Slats
Boeing 737
Flaps

176. LIFT AUGMENTATION
 Lift augmentation system. A Lift augmentation system is a device
installed on the wing of an aircraft to produce an increase in lift at a
given speed
 It is useful at low speed because it reduces the stall speed (the plane can
fly more slowly)
281
Kruegar Flap design with
slats extended

177. SLATS AND SLOTS
 Slats are aerodynamic surfaces in
the leading edge, which when
deployed, allows the wing to
operate at higher angle of attack.
 When deployed, the slat opens up
a slot between itself and the wing.
 In some aircraft, the slats are fixed,
which opens up a slot between the
wing and the slat. 282

178. FLAPS
 Flaps are usually mounted on the wing trailing edges of a fixed-wing
aircraft. Flaps are used for extra lift on take-off and for slower approach
speeds for landing
 Flaps also cause an increase in drag in mid-flight, so they are retracted
when not needed.
283
• There are four basic types of flaps:
• Plain
• Split (Can go Asymetric and dangerous)
• Fowler
• Slotted.

179. PLAIN FLAP
 The rear portion of aerofoil rotates downwards on a simple
hinge mounted at the front of the flap
284

180. SPLIT FLAP
 The rear portion of the lower surface of the aerofoil hinges
downwards from the leading edge of the flap, while the upper
surface stays immobile
285

181. SLOTTED FLAP
 This type provides a gap between the flap and the wing forces high pressure air
from below the wing is directed over the flap helping the airflow remain
attached to the flap increasing lift compared to a split flap
286
https://www.boldmethod.com/learn-to-fly/aircraft-systems/how-the-four-types-of-aircraft-flaps-
Extension of Flap to role needed

182. SLOTTED FLAP
 This type provides a gap between the flap and the wing forces high pressure air
from below the wing over the flap helping the airflow remain attached to the
flap, increasing lift compared to a split flap.
287

183. SLOTTED FLAP
 Additionally, lift across the entire chord of the primary aerofoil is greatly
increased as the velocity of air leaving its trailing edge is raised, from the typical
non-flap 80% of freestream, to that of the higher-speed, lower-pressure air
flowing around the leading edge of the slotted flap. Any flap that allows air to
pass between the wing and the flap is considered a slotted flap.
288

184. FOWLER FLAP
 A split flap that slides backwards, before
hinging downward, thereby increasing
first chord, then camber.
 The flap may form part of the upper
surface of the wing, like a plain flap, or it
may not, like a split flap, but it must slide
rearward before lowering
289

185. DOUBLE SLOTTED FOWLER FLAP
 Further enhances high lift at lower approach speeds
290

186. 291
Flap Types: Recap

187. 292
Flap Types: Many more names and designs

188. KRUEGER FLAPS
 A hinged flap which folds out from under the wing's leading edge
while not forming a part of the leading edge of the wing when
retracted.
 This increases the camber and thickness of the wing, which in turn
increases lift and drag.
293
Boeing 727's
Krueger flaps

189. ASYMMETRIC FLAP (DANGEROUS FAULT)
 An asymmetric or split flap condition is one in which the
flap(s) on one wing extends or retracts while the one(s) on
the other wing remains in position
 The situation can be caused by mechanical failure or
jamming
294
What will happen next?

190. ASYMMETRIC FLAP (DANGEROUS FAULT):
 If the situation is allowed to progress unchecked, it will result in a pronounced
roll towards the wing with the lesser amount of flap extended
 In this case, it is possible that the induced roll could exceed the amount of
aileron authority available and could result in a spin or other loss of control
situation
 In all cases of asymmetric flap, the wing with the greater amount of flap
extended produces more lift. As a consequence, the wing with the lesser
amount of flap extended will stall first
295
Small Break back at 09.51

191.  A vortex generator is a small angled plate installed on an outer surface of an
aerodynamic body..
 The angle of the plate causes the air to swirl, creating a vortex behind it.
 This effect allows the air flow to remain ‘attached’ to the surface even at
points where the flow without a vortex would separate from the surface
296
VORTEX
GENERATORS
https://www
.youtube.co
m/watch?v
=uXYLCxq5
YjA

192.  HERE
297

193. 298
VORTEX
GENERATORS

194. 299
VORTEX
GENERATORS NOISE REDUCTION
Vortex generators have been used on the wing underside of Airbus A320 family aircraft to reduce
noise generated by airflow over circular pressure equalisation vents for the fuel tanks. Lufthansa
claims a noise reduction of up to 2 dB can thus be achieved.[1

195. BOUNDARY LAYER CONTROL METHODS
300
https://phys.org/ne
ws/2012-09-
scientists-purpose-
vortex.html

196. BOUNDARY LAYER CONTROL METHODS
301
https://phys.org/ne
ws/2012-09-
scientists-purpose-
vortex.html
Gloster Javelin showing the three sets of vortex
generators located along the outer portion of the wing

197. BOUNDARY LAYER CONTROL METHODS
302
Gloster Javelin showing the three sets of vortex
generators located along the outer portion of the wing
• Three sets of vortex generators are used
along the Javelin's outer wing with one set
located near the leading edge, another just
before the ailerons, and a third set in between
A Buccanner folding its wings, note the
vortex generators near the leading edge

198. BOUNDARY LAYER CONTROL METHODS
303
• The generators on both planes serve to break up the
shocks formed at transonic speeds thereby delaying the
effects of separation.
• The generators located just ahead of the ailerons on the
Javelin wing also help improve the effectiveness of
these control surfaces at low speed or high angle of
attack

199. BOUNDARY LAYER SHORT TAKE OFF AND LANDING
304
• These aircraft generally must operate at low
speeds during take-off and landing, so the
flow speed over the wings tends to be low
as well
• Aircraft like the C-17 Globemaster
III transport use vortex generators to create
a higher-speed flow over the wings and
control surfaces at these conditions to
improve performance and controllability
• In the case of the C-17, the vortex
generators are located on the sides of the
engine nacelles rather than on the wings
but they still produce the same beneficial
effects.
Large vortex generator plates visible on the engine
cowlings of a C-17
http://www.aerospaceweb.org/question/aerodynamics/q0009.sht
ml

200. BOUNDARY LAYER : THE FUTURE?
305
https://www.nasa.gov/feature/glenn/2019/memory-metals-are-shaping-the-evolution-of-aviation
https://aerospaceamerica.aiaa.org/departments/testing-vortex-generators-that-get-out-of-
the-way/
Class Exercise: Research and get good
examples (lots of pictures with simple
explanation) of:
• Other Vortex Generators
• Wing Fences
• Saw Tooth profiles
• Dog Tooth profiles
• Strakes
• Lerx’s
• Cuff
• And any other strange things!
Upload to Folder for this week
https://www.motorbiscuit.com/do-vortex-generators-
actually-help-road-cars/
So... Derated Thrust Takeoffs

201. BOUNDARY LAYER : FENCES
306

202. BOUNDARY LAYER : OTHER DESIGNS TO CONTROL AIR
307

204. PRINCIPLES OF AERODYNAMICS THEORY OF FLIGHT
BETEC L2 UNIT 3 LO 6.1 KNOW THE PURPOSE AND OPERATION OF SECONDARY CONTROL SURFACES
309
07 Jun 2021

205. BOUNDARY LAYER : THE FUTURE?
310
https://www.nasa.gov/feature/glenn/2019/memory-metals-are-shaping-the-evolution-of-aviation
https://aerospaceamerica.aiaa.org/departments/testing-vortex-generators-that-get-out-of-
the-way/
Class Exercise: Research and get good
examples (lots of pictures with simple
explanation) of:
• Other Vortex Generators
• Wing Fences
• Saw Tooth profiles
• Dog Tooth profiles
• Strakes
• Lerx’s
• Cuff
• And any other strange things!
Upload to Folder for this week
https://www.motorbiscuit.com/do-vortex-generators-
actually-help-road-cars/
So... Derated Thrust Takeoffs

206. LO 6: Know the purpose and operation of a range of secondary control
surfaces
Spoilers
• A spoiler (sometimes called a lift
spoiler or lift dumper)
• Intentionally reduces the lift component
of an aerofoil in a controlled way
• Basically, plates on the top surface of a
wing that can be extended upward into
the airflow to spoil the streamline flow

207. AC 6.1 Describe the operation of high drag devices, by stating the
limitations in flight and on the ground of: spoilers, lift dumpers and
speed brakes
LO 6: Know the purpose and operation of a range of secondary control
surfaces
Spoilers
• By so doing, the spoiler creates
a controlled stall over the
portion of the wing behind it,
greatly reducing the lift of that
wing section

208. AC 6.1 Describe the operation of high drag devices, by stating the
limitations in flight and on the ground of: spoilers, lift dumpers and
speed brakes
LO 6: Know the purpose and operation of a range of secondary control
surfaces
Spoilers
• Spoilers fall into two categories:
• Flight Spoilers to increase descent rate
or control roll
• Ground Spoilers that are fully deployed
immediately on landing to greatly
reduce lift (‘lift dumpers’) and increase
drag.

209. AC 6.1 Describe the operation of high drag devices, by stating the
limitations in flight and on the ground of: spoilers, lift dumpers and
speed brakes
LO 6: Know the purpose and operation of a range of secondary control
surfaces
Fight Spoilers on Take off
Landing
• Larger aircraft, the primary concern is just to keep
the upwind wing from rising… there is no need to
raise the downwind wing and there is no need for
a counteracting force on the downwind wing…
spoilers just work better than ailerons in this
particular scenario.
• The aircraft will take off in a wings-level attitude,
and if the pilot continues to hold roll pressure, the
aircraft will bank upwind as soon as the airplane
leaves the ground..

210. AC 6.1 Describe the operation of high drag devices, by stating the
limitations in flight and on the ground of: spoilers, lift dumpers and
speed brakes
LO 6: Know the purpose and operation of a range of secondary control
surfaces
Spoilers
• In modern fly-by-wire
aircraft, the same set
of control surfaces
serve both functions.

211. AC 6.1 Describe the operation of high drag devices, by stating the
limitations in flight and on the ground of: spoilers, lift dumpers and
speed brakes
LO 6: Know the purpose and operation of a range of secondary control
surfaces
Spoilers
• The primary purpose of
the ground spoilers is to
maximise wheel brake
efficiency by "spoiling" or
dumping the lift
generated by the wing

212. AC 6.1 Describe the operation of high drag devices, by stating the
limitations in flight and on the ground of: spoilers, lift dumpers and
speed brakes
LO 6: Know the purpose and operation of a range of secondary control
surfaces
Spoilers
• This forces the full weight of
the aircraft onto the landing gear
• The spoiler panels also help
slow the aircraft by producing
aerodynamic drag

213. AC 6.1 Describe the operation of high drag devices, by stating the
limitations in flight and on the ground of: spoilers, lift dumpers and
speed brakes
LO 6: Know the purpose and operation of a range of secondary control
surfaces
Spoilers
• Increase form drag created by the spoilers directly assists the
braking effect.
• However, the real gain comes as the spoilers cause a
dramatic loss of lift and hence the weight of the aircraft is
transferred from the wings to the undercarriage
• This allows the wheels to be mechanically braked with less
tendency to skid.

214. AC 6.1 Describe the operation of high drag devices, by stating the
limitations in flight and on the ground of: spoilers, lift dumpers and
speed brakes
LO 6: Know the purpose and operation of a range of secondary control
surfaces
Spoilers v Airbrakes
• Spoilers differ from airbrakes:
• Airbrakes are designed to
increase drag without affecting
lift,
• Spoilers reduce lift as well as
increasing drag.

215. AC 6.1 Describe the operation of high drag devices, by stating the limitations in flight
and on the ground of: spoilers, lift dumpers and speed brakes
LO 6: Know the purpose and operation of a range of secondary control
surfaces
Spoiler Angles

216. AC 6.1 Describe the operation of high drag devices, by stating the limitations in flight
and on the ground of: spoilers, lift dumpers and speed brakes
LO 6: Know the purpose and operation of a range of secondary control
surfaces
Combinations
• Some aircraft use spoilers in combination
with or in lieu of ailerons for roll control
• This primarily to reduce adverse
yaw when rudder input is limited by
higher speeds.
• For such spoilers the term spoileron has
been coined.

217. AC 6.1 Describe the operation of high drag devices, by stating the limitations in flight
and on the ground of: spoilers, lift dumpers and speed brakes
LO 6: Know the purpose and operation of a range of secondary control
surfaces
Roll spoilers
• On large aircraft where rudder use is inappropriate at high speeds or
ailerons are too small at low speeds, roll spoilers (also
called spoileronns) can be used to minimise adverse yaw or increase
roll moment.
• To function as a lateral control, the spoiler is raised on the down-
going wing (up aileron) and remains retracted on the other wing. The
raised spoiler increases the drag, and so the yaw is in the same
direction as the roll.

218. AC 6.1 Describe the operation of high drag devices, by stating the limitations in flight
and on the ground of: spoilers, lift dumpers and speed brakes
LO 6: Know the purpose and operation of a range of secondary control
surfaces
Combinations
• Spoilerons roll an aircraft by reducing
the lift of the downward-going wing.
• Unlike ailerons, spoilers do not
increase the lift of the upward-going
wing.
• A raised spoileron also increases the
drag on the wing where it is deployed,
causing the aircraft to yaw.

219. AC 6.1 Describe the operation of high drag devices, by stating the limitations in flight
and on the ground of: spoilers, lift dumpers and speed brakes
LO 6: Know the purpose and operation of a range of secondary control
surfaces
Combinations
Spoilerons can be used
to assist ailerons or to
replace them entirely, as
in the B-52G which
required an extra spoiler
segment in place of
ailerons present on other
B-52 models
Break back at 14.30

220. AC 6.1 Describe the operation of high drag devices, by stating the
limitations in flight and on the ground of: spoilers, lift dumpers and
speed brakes
LO 6: Know the purpose and operation of a range of secondary control
surfaces
Spoilers
• This forces the full weight of
the aircraft onto the landing gear.
• The spoiler panels also help
slow the aircraft by producing
aerodynamic drag

221. ADVERSE YAW ON ROLL RATE DUTCH ROLL
 In a laterally stable aircraft,
sideslip produced by adverse
yaw reduces roll rate because of
the opposing rolling moment from
dihedral effect.
 Rolling in one direction while
yawing in another can also set off
Dutch roll oscillation, seen in the
figure as an oscillation in roll
rate over time. 327
https://www.youtube.com/watch?v=9Gt-IcCBiQ4
https://www.youtube.com/watch?v=kOBbAFzXrRg&t=24s

222. ADVERSE YAW ON ROLL RATE DUTCH ROLL
 Dutch Roll and Yaw Damper
 Out of Phase Turns
 Lateral (Roll) Stronger
 Directional (Yaw) Weaker
 Stability is achieved by a Yaw
damper
328
https://www.youtube.com/watch?v=PtALTmdfD30
https://www.youtube.com/watch?v=2dfFIhEUDNs

223. RUDDER LIMITERS
A rudder travel limiter, or rudder limiter, is a
controlling device in an aircraft used to
mechanically limit the maximum rudder
deflection.
The rudder travel limiter in the Airbus A300-600 is
controlled by the Feel and Limitation Computers
(FLC) maintaining sufficient yaw control within the
entire flight envelope and limiting excessive lateral
loads on the rudder and vertical stabilizer
329

224. PRINCIPLES OF AERODYNAMICS THEORY OF FLIGHT
BETEC L2 UNIT 3 LO 6 KNOW THE PURPOSE AND OPERATION OF SECONDARY CONTROL SURFACES
330
09 Jun 2021

225. CONSOLIDATE
https://www.youtube.com/watch?v=z2J_LUDWioA
• Understanding Spoilers
• Understanding Adverse Roll
• Understanding Dutch Roll (The stability fight)
• Understanding a yaw damper system
• Explain why do we have Rudder Limiters in flight
(example)
• Explain why V Tailed aircraft have secondary roll
problems when applying a rudder movement
• Upload Word Document addressing your understanding

226. AC 6.2 Describe the secondary effects of roll and yaw and methods to overcome
them
LO 6: Know the purpose and operation of a range of secondary control
surfaces
Adverse Yaw
• Is a natural, and
undesirable,
tendency for an
aircraft to yaw in
the opposite
direction of a roll.

227. AC 6.2 Describe the operation of high drag devices, by stating the limitations in flight
and on the ground of: spoilers, lift dumpers and speed brakes
LO 6: Know the purpose and operation of a range of secondary control
surfaces
Adverse Yaw
• It is caused by
the difference in
lift and drag of
each wing.

228. AC 6.2 Describe the operation of high drag devices, by stating the limitations in flight
and on the ground of: spoilers, lift dumpers and speed brakes
LO 6: Know the purpose and operation of a range of secondary control
surfaces
Adverse Yaw
• The effect can be greatly minimized with ailerons deliberately
designed to create drag when deflected upward and/
• or mechanisms which automatically apply some amount of
coordinated rudder
• However, mechanically rudder coupling it to the ailerons is
impractical, therefore electronic coupling is commonplace in
fly-by-wire aircraft.

229. AC 6.2 Describe the operation of high drag devices, by stating the limitations in flight
and on the ground of: spoilers, lift dumpers and speed brakes
LO 6: Know the purpose and operation of a range of secondary control
surfaces
Compensating for Adverse Yaw
Most airplanes use this
method of adverse yaw
mitigation

230. ALL MOVING TAILPLANE
 A stabilator, more frequently all-moving tail
or all-flying tail, is a fully movable aircraft
stabilizer.
 It serves and gives the usual functions of
longitudinal stability, control and stick force
requirements otherwise performed by the
separate parts of a conventional horizontal
stabilizer and elevator
 They are both found at the rear of an aircraft
and both serve a similar purpose. Despite
this, there are distinct differences between
these two components of the empennage.
338

231. ALL MOVING TAILPLANE
 It, along with the horizontal stabilizer,
maintains the pitch, lift, and angle of attack
of an aircraft
 stabilator has a tidier design and provides a
larger surface for pitch control, it is more
effective in allowing for smoother
ascension and descension
 Feature of a stabilator, called the anti-servo,
is an additional flap at the rear of the
stabilator
 Antiservo’s role is to make the aircraft
stabilator less sensitive and help it stay in
the optimal position 339
https://www.youtube.com/watch?v=6hZQeTrmcjU
General Dynamics F-16 Fighting
Falcon jet fighter parked at an airshow,
with stabilators deflected downwards.

232. ALL MOVING TAILPLANE
 The trim tab, another feature of an
aircraft’s tail section, moves parallel to
the stabilator at a greater pace
 The result is that the effort required to
move the yoke, (pilots control)
heightens relative to airspeed and
control deflection
 This is a safety measure that increases
control along the longitudinal axis and
stops the pilot from over controlling
340
https://www.youtube.com/watch?v=l62NvkRWa5E

233. ALL MOVING TAILPLANE
 This is due to the weight
balance stabilators ability to
continue controlling pitch through a
variety of flight speeds, including
supersonic flight.
 Non-delta winged supersonic aircraft
use stabilators because conventional
elevators can allow shock waves to
form.
341

234. ALL MOVING TAILPLANE
 Shock waves strongly diminish the
effectiveness of elevators, thereby
causing a dangerous aerodynamic
phenomenon called mach tuck.
 Mach tuck will cause the nose of an
aircraft to pitch downward when air
flows past the wings at supersonic
speeds.
342
https://www.boldmethod.com/blog/lists/2019/05/mach-tuck-explained-in-eight-
steps/

235. CANARDS
 Canards are part of an airplane that
functions as a stabilizer or elevator
and installed in front of the main
wing
 A canard is used for several reasons
such as increasing lifting force, the
stability of the aircraft's controls
and flow changes over the main
wing
343
Everything on Canards!

236. FLAPERONS
 A flaperon on an aircraft's wing is a type of
control surface that combines the functions
of both flaps and ailerons.
 Some smaller kit planes have flaperons for
reasons of simplicity of manufacture, while
some large commercial aircraft may have a
flaperon between the flaps and aileron
 Flaperons help to stabilize the plane during
low-speed flying during take-off and
landing
344

237. ELEVONS
 Elevons or tailerons are aircraft control
surfaces that combine the functions of the
elevator (used for pitch control) and the
aileron (used for roll control), hence the
name
 They are frequently used on tailless aircraft
such as flying wings.
 An elevon that is not part of the main
wing, but instead is a separate tail surface,
is a stabilator (but stabilators are also used
for pitch control only, with no roll
function)
345
Dual controls
Classwork catch up and
identify 3 aircraft that have
these configurations and why
were they used in their
design?

238. TAILERONS
347

239. RUDDERVATORS
 A butterfly, or Vee, tail,
which combines the effect
of the rudder and the
elevators.
 These are movable
surfaces
 They cause the aircraft to
pitch up or down when they
move together and yaw
when they move
differentially 348

240. RUDDERVATORS
349

241. STABILATORS
 A stabilator, more frequently all-moving
tail or all-flying tail, is a fully movable
aircraft stabilizer
 It serves the usual functions of longitudinal
stability, control and stick force
requirements otherwise performed by the
separate parts of a conventional horizontal
stabiliser and elevator
 Apart from a higher efficiency at high Mach
number, it is a useful device for changing the
aircraft balance within wide limits, and for
mastering the stick forces 350

242. STABILATORS
351

243. SPOILERONS
352

244. CONTROL BALANCE PANELS
 Balance Panel. A flat panel hinged to the leading edge of some ailerons that
produces a force which assists the pilot in holding the ailerons deflected.
353
https://www.youtube.com/watch?v=IZafheouwnI

245. CONTROL MASS BALANCING TO BUILD OUT FLUTTER OSCILLATIONS
354
• Flutter occurs when the control surface is displaced
from its intended deflection. Because the ailerons are
on the long, narrow wings which can twist under load,
they are the surface most prone to oscillate
• If the centre of gravity is behind the hinge, the surface
can move like a pendulum and undergo forced simple
harmonic motion with increasing amplitude
• Adding balancing weights which make the centre of
gravity and hinge line coincident solves the problem.
These weights may be in the nose of the surface, or
lighter masses attached further ahead of the hinge
externally

246. MECHANICAL SPRING CONTROL TABS
355
Many tab linkages have a
spring tab that kicks in
(assists) as the forces
needed to deflect a control
increase with speed and the
angle of desired deflection.

247. SUMMARY OF FLIGHT CONTROL TABS
356

248. LIFT AUGMENTATION DEVICES AND HOW THEY WORK
Slats and Flaps
• A Lift augmentation system is a device installed on the wing of an
aircraft to produce an increase in lift at a given speed
• It can be installed on the leading edge of the wing (‘leading edge slats’)
• or on the trailing edge (‘wing flaps’)
Boeing 727
Slats
Boeing 737
Flaps

249. LIFT AUGMENTATION
 Lift augmentation system. A Lift augmentation system is a device
installed on the wing of an aircraft to produce an increase in lift at a
given speed
 It is useful at low speed because it reduces the stall speed (the plane can
fly more slowly)
358
Kruegar Flap design with
slats extended

250. FLAPS
 Flaps are usually mounted on the wing trailing edges of a fixed-wing
aircraft. Flaps are used for extra lift on take-off and for slower approach
speeds for landing
 Flaps also cause an increase in drag in mid-flight, so they are retracted
when not needed.
359
• There are four basic types of flaps:
• Plain
• Split (Can go Asymetric and dangerous)
• Fowler
• Slotted.

251. PLAIN FLAP
 The rear portion of aerofoil rotates downwards on a simple
hinge mounted at the front of the flap
360

252. SPLIT FLAP
 The rear portion of the lower surface of the aerofoil hinges
downwards from the leading edge of the flap, while the upper
surface stays immobile
361

253. SLOTTED FLAP
 This type provides a gap between the flap and the wing forces high pressure air
from below the wing is directed over the flap helping the airflow remain
attached to the flap increasing lift compared to a split flap
362
https://www.boldmethod.com/learn-to-fly/aircraft-systems/how-the-four-types-of-aircraft-flaps-
Extension of Flap to role needed

254. SLOTTED FLAP
 This type provides a gap between the flap and the wing forces high pressure air
from below the wing over the flap helping the airflow remain attached to the
flap, increasing lift compared to a split flap.
363

255. SLOTTED FLAP
 Additionally, lift across the entire chord of the primary aerofoil is greatly
increased as the velocity of air leaving its trailing edge is raised, from the typical
non-flap 80% of freestream, to that of the higher-speed, lower-pressure air
flowing around the leading edge of the slotted flap. Any flap that allows air to
pass between the wing and the flap is considered a slotted flap.
364

256. SLATS AND SLOTS
 Slats are aerodynamic surfaces in
the leading edge, which when
deployed, allows the wing to
operate at higher angle of attack.
 When deployed, the slat opens up
a slot between itself and the wing.
 In some aircraft, the slats are fixed,
which opens up a slot between the
wing and the slat. 365

257. FOWLER FLAP
 A split flap that slides backwards, before
hinging downward, thereby increasing
first chord, then camber.
 The flap may form part of the upper
surface of the wing, like a plain flap, or it
may not, like a split flap, but it must slide
rearward before lowering
366

258. DOUBLE SLOTTED FOWLER FLAP
 Further enhances high lift at lower approach speeds
367

259. 368
Flap Types: Recap

260. 369
Flap Types: Many more names and designs

261. LEADING EDGE KRUEGER FLAPS
 A hinged flap which folds out from under the wing's leading edge
while not forming a part of the leading edge of the wing when
retracted.
 This increases the camber and thickness of the wing, which in turn
increases lift and drag.
370
Boeing 727's
Krueger flaps

262. SOW Where we are!
371
Check of understanding
AC 6.4 Describe the aerodynamic problems caused by asymmetric flap operation
● Describe asymmetric flap and the effect on aircraft attitude, including asymmetric flap and how it happens, effect on
aircraft attitude
AC 6.5 Describe the purpose and operation of devices to prevent stalls
● Know the operation of stall strips/wedges; know methods of boundary layer control, blown air, suction
devices, vortex generators

263. ASYMMETRIC FLAP (DANGEROUS FAULT)
 An asymmetric or split flap condition is one in which the
flap(s) on one wing extends or retracts while the one(s) on
the other wing remains in position
 The situation can be caused by mechanical failure or
jamming
372
What will happen next?

264. ASYMMETRIC FLAP (DANGEROUS FAULT):
 If the situation is allowed to progress unchecked, it will result in a pronounced
roll towards the wing with the lesser amount of flap extended
 In this case, it is possible that the induced roll could exceed the amount of
aileron authority available and could result in a spin or other loss of control
situation
 In all cases of asymmetric flap, the wing with the greater amount of flap
extended produces more lift. As a consequence, the wing with the lesser
amount of flap extended will stall first
373
https://www.youtube.com/watch?v=WTGRt0ubkSY
https://www.boldmethod.com/learn-to-
fly/aerodynamics/landing-with-an-asymmetric-split-
flap-failure/

265. SOW Where we are!
375
AC 6.5 Describe the purpose and operation of devices to prevent
stalls
● Know the operation of stall strips/wedges; know methods of
boundary layer control, blown air, suction devices, vortex
generators

266. ASYMMETRIC FLAP (DANGEROUS FAULT) RECAP OF LESSON
 An asymmetric or split flap condition is one in which the
flap(s) on one wing extends or retracts while the one(s) on
the other wing remains in position
 The situation can be caused by mechanical failure or
jamming
376
What will happen next?

267. BOUNDARY LAYER : OTHER DESIGNS TO CONTROL AIR
377

268. BOUNDARY LAYER : THE FUTURE? CLASS EXERCISE
378
https://www.nasa.gov/feature/glenn/2019/memory-metals-are-shaping-the-evolution-of-aviation
https://aerospaceamerica.aiaa.org/departments/testing-vortex-generators-that-get-out-of-
the-way/
Other Vortex Generators
• Wing Fences
• Saw Tooth profiles
• Dog Tooth profiles
• Strakes
• Lerx’s
• Cuff
• And any other strange things!
https://www.motorbiscuit.com/do-vortex-generators-
actually-help-road-cars/ So... Derated Thrust Takeoffs

269. CLASSWORK UPLOADS
379

270. STALL STRIPS/WEDGES
 Stall strips are small obstructions that impede
the smooth flow of air over the wing at high
angles of attack.
 As the wing increases its angle of attack,
airflow is eventually disturbed by the stall strip
 This causes this part of the wing to stall at a
lower angle of attack than it would otherwise
380

271.  Boundary layer control by mass injecting (blowing) prevents boundary
layer separation by supplying additional energy to the particles of fluid which
are being retarded in the boundary layer.
381
Boundary Layer Control (Blowing and suction)
https://alchetron.com/Boundary-layer-control

272. 382
Boundary Layer Control (Blown Flaps)
Blown flaps, or jet flaps, are
powered aerodynamic high-lift
devices used on the wings of
certain aircraft to improve
their low-speed flight
characteristics
Hunting H.126 at the RAF Museum
Cosford (1976) Research aircraft
https://en.wikipedia.org/wiki/List_of_experimental_aircraft

273. 383
Boundary Layer Control (Blown Flaps)
Some Mig 21 used Blown Flaps. The
Mig 21 made aviation records,
became the most-produced
supersonic jet aircraft in aviation
history, the most-produced combat
aircraft since the Korean War and
previously the longest production run
of a combat aircraft (now exceeded
by both the McDonnell Douglas F-15
Eagle and General Dynamics F-16
Fighting Falcon). MiG-21 Lancer-C in flight
https://en.wikipedia.org/wiki/Mikoyan-Gurevich_MiG-21

274. 384
Boundary Layer Control (Blown Flaps)
Blown Flaps generally fell from favour
because they imposed a significant
maintenance overhead in keeping the
ductwork clean and various valve
systems working properly, along with
the disadvantage that an engine
failure reduced lift in precisely the
situation where it is most desired.
Buccaneer
A depiction of the Buccaneer, the blowing slots visible on
the leading edges and the wing flaps are highlighted; these
aerodynamic features contribute to the Coandă airflow over
the wing.

275. 385
Boundary Layer Control (Suction)
https://en.wikipedia.org/wiki/Northrop_X-21
• As flow separation results from the velocity deficit that is characteristic of
boundary layers, suction attempts to remove the boundary layer from the
surface before it can separate. Improvements in fuel efficiency have been
estimated as high as 30%!
• Theoretically, reduced drag,
better fuel economy and longer
range could be achieved.
• The experiment was cancelled
due to the weight of the
compressors being too
prohibitive

276. MOCK TEST QUESTIONS
http://www.captonline.com/Mocks/POFA1/quiz_html5.html
https://quizlet.com/307767096/theory-of-flight-flash-
cards/
Revision for 30 mins on these brilliant Flash Cards !
Test for 30 mins and email result to me

277. MOCK TEST QUESTIONS: WE DONE THIS… ANOTHER TEST THIS WEEK ?
Register class first Mark Quiz for 30 mins
https://quizizz.com/admin/quiz/5a611271eb23ff001c2b8a57/forces
-of-flight

278. 390
THE SLIDE EXTRAS
Good Recap all things wing