- •Textbook Series
- •Contents
- •1 Overview and Definitions
- •Overview
- •General Definitions
- •Glossary
- •List of Symbols
- •Greek Symbols
- •Others
- •Self-assessment Questions
- •Answers
- •2 The Atmosphere
- •Introduction
- •The Physical Properties of Air
- •Static Pressure
- •Temperature
- •Air Density
- •International Standard Atmosphere (ISA)
- •Dynamic Pressure
- •Key Facts
- •Measuring Dynamic Pressure
- •Relationships between Airspeeds
- •Airspeed
- •Errors and Corrections
- •V Speeds
- •Summary
- •Questions
- •Answers
- •3 Basic Aerodynamic Theory
- •The Principle of Continuity
- •Bernoulli’s Theorem
- •Streamlines and the Streamtube
- •Summary
- •Questions
- •Answers
- •4 Subsonic Airflow
- •Aerofoil Terminology
- •Basics about Airflow
- •Two Dimensional Airflow
- •Summary
- •Questions
- •Answers
- •5 Lift
- •Aerodynamic Force Coefficient
- •The Basic Lift Equation
- •Review:
- •The Lift Curve
- •Interpretation of the Lift Curve
- •Density Altitude
- •Aerofoil Section Lift Characteristics
- •Introduction to Drag Characteristics
- •Lift/Drag Ratio
- •Effect of Aircraft Weight on Minimum Flight Speed
- •Condition of the Surface
- •Flight at High Lift Conditions
- •Three Dimensional Airflow
- •Wing Terminology
- •Wing Tip Vortices
- •Wake Turbulence: (Ref: AIC P 072/2010)
- •Ground Effect
- •Conclusion
- •Summary
- •Answers from page 77
- •Answers from page 78
- •Questions
- •Answers
- •6 Drag
- •Introduction
- •Parasite Drag
- •Induced Drag
- •Methods of Reducing Induced Drag
- •Effect of Lift on Parasite Drag
- •Aeroplane Total Drag
- •The Effect of Aircraft Gross Weight on Total Drag
- •The Effect of Altitude on Total Drag
- •The Effect of Configuration on Total Drag
- •Speed Stability
- •Power Required (Introduction)
- •Summary
- •Questions
- •Annex C
- •Answers
- •7 Stalling
- •Introduction
- •Cause of the Stall
- •The Lift Curve
- •Stall Recovery
- •Aircraft Behaviour Close to the Stall
- •Use of Flight Controls Close to the Stall
- •Stall Recognition
- •Stall Speed
- •Stall Warning
- •Artificial Stall Warning Devices
- •Basic Stall Requirements (EASA and FAR)
- •Wing Design Characteristics
- •The Effect of Aerofoil Section
- •The Effect of Wing Planform
- •Key Facts 1
- •Super Stall (Deep Stall)
- •Factors that Affect Stall Speed
- •1g Stall Speed
- •Effect of Weight Change on Stall Speed
- •Composition and Resolution of Forces
- •Using Trigonometry to Resolve Forces
- •Lift Increase in a Level Turn
- •Effect of Load Factor on Stall Speed
- •Effect of High Lift Devices on Stall Speed
- •Effect of CG Position on Stall Speed
- •Effect of Landing Gear on the Stall Speed
- •Effect of Engine Power on Stall Speed
- •Effect of Mach Number (Compressibility) on Stall Speed
- •Effect of Wing Contamination on Stall Speed
- •Warning to the Pilot of Icing-induced Stalls
- •Stabilizer Stall Due to Ice
- •Effect of Heavy Rain on Stall Speed
- •Stall and Recovery Characteristics of Canards
- •Spinning
- •Primary Causes of a Spin
- •Phases of a Spin
- •The Effect of Mass and Balance on Spins
- •Spin Recovery
- •Special Phenomena of Stall
- •High Speed Buffet (Shock Stall)
- •Answers to Questions on Page 173
- •Key Facts 2
- •Questions
- •Key Facts 1 (Completed)
- •Key Facts 2 (Completed)
- •Answers
- •8 High Lift Devices
- •Purpose of High Lift Devices
- •Take-off and Landing Speeds
- •Augmentation
- •Flaps
- •Trailing Edge Flaps
- •Plain Flap
- •Split Flap
- •Slotted and Multiple Slotted Flaps
- •The Fowler Flap
- •Comparison of Trailing Edge Flaps
- •and Stalling Angle
- •Drag
- •Lift / Drag Ratio
- •Pitching Moment
- •Centre of Pressure Movement
- •Change of Downwash
- •Overall Pitch Change
- •Aircraft Attitude with Flaps Lowered
- •Leading Edge High Lift Devices
- •Leading Edge Flaps
- •Effect of Leading Edge Flaps on Lift
- •Leading Edge Slots
- •Leading Edge Slat
- •Automatic Slots
- •Disadvantages of the Slot
- •Drag and Pitching Moment of Leading Edge Devices
- •Trailing Edge Plus Leading Edge Devices
- •Sequence of Operation
- •Asymmetry of High Lift Devices
- •Flap Load Relief System
- •Choice of Flap Setting for Take-off, Climb and Landing
- •Management of High Lift Devices
- •Flap Extension Prior to Landing
- •Questions
- •Annexes
- •Answers
- •9 Airframe Contamination
- •Introduction
- •Types of Contamination
- •Effect of Frost and Ice on the Aircraft
- •Effect on Instruments
- •Effect on Controls
- •Water Contamination
- •Airframe Aging
- •Questions
- •Answers
- •10 Stability and Control
- •Introduction
- •Static Stability
- •Aeroplane Reference Axes
- •Static Longitudinal Stability
- •Neutral Point
- •Static Margin
- •Trim and Controllability
- •Key Facts 1
- •Graphic Presentation of Static Longitudinal Stability
- •Contribution of the Component Surfaces
- •Power-off Stability
- •Effect of CG Position
- •Power Effects
- •High Lift Devices
- •Control Force Stability
- •Manoeuvre Stability
- •Stick Force Per ‘g’
- •Tailoring Control Forces
- •Longitudinal Control
- •Manoeuvring Control Requirement
- •Take-off Control Requirement
- •Landing Control Requirement
- •Dynamic Stability
- •Longitudinal Dynamic Stability
- •Long Period Oscillation (Phugoid)
- •Short Period Oscillation
- •Directional Stability and Control
- •Sideslip Angle
- •Static Directional Stability
- •Contribution of the Aeroplane Components.
- •Lateral Stability and Control
- •Static Lateral Stability
- •Contribution of the Aeroplane Components
- •Lateral Dynamic Effects
- •Spiral Divergence
- •Dutch Roll
- •Pilot Induced Oscillation (PIO)
- •High Mach Numbers
- •Mach Trim
- •Key Facts 2
- •Summary
- •Questions
- •Key Facts 1 (Completed)
- •Key Facts 2 (Completed)
- •Answers
- •11 Controls
- •Introduction
- •Hinge Moments
- •Control Balancing
- •Mass Balance
- •Longitudinal Control
- •Lateral Control
- •Speed Brakes
- •Directional Control
- •Secondary Effects of Controls
- •Trimming
- •Questions
- •Answers
- •12 Flight Mechanics
- •Introduction
- •Straight Horizontal Steady Flight
- •Tailplane and Elevator
- •Balance of Forces
- •Straight Steady Climb
- •Climb Angle
- •Effect of Weight, Altitude and Temperature.
- •Power-on Descent
- •Emergency Descent
- •Glide
- •Rate of Descent in the Glide
- •Turning
- •Flight with Asymmetric Thrust
- •Summary of Minimum Control Speeds
- •Questions
- •Answers
- •13 High Speed Flight
- •Introduction
- •Speed of Sound
- •Mach Number
- •Effect on Mach Number of Climbing at a Constant IAS
- •Variation of TAS with Altitude at a Constant Mach Number
- •Influence of Temperature on Mach Number at a Constant Flight Level and IAS
- •Subdivisions of Aerodynamic Flow
- •Propagation of Pressure Waves
- •Normal Shock Waves
- •Critical Mach Number
- •Pressure Distribution at Transonic Mach Numbers
- •Properties of a Normal Shock Wave
- •Oblique Shock Waves
- •Effects of Shock Wave Formation
- •Buffet
- •Factors Which Affect the Buffet Boundaries
- •The Buffet Margin
- •Use of the Buffet Onset Chart
- •Delaying or Reducing the Effects of Compressibility
- •Aerodynamic Heating
- •Mach Angle
- •Mach Cone
- •Area (Zone) of Influence
- •Bow Wave
- •Expansion Waves
- •Sonic Bang
- •Methods of Improving Control at Transonic Speeds
- •Questions
- •Answers
- •14 Limitations
- •Operating Limit Speeds
- •Loads and Safety Factors
- •Loads on the Structure
- •Load Factor
- •Boundary
- •Design Manoeuvring Speed, V
- •Effect of Altitude on V
- •Effect of Aircraft Weight on V
- •Design Cruising Speed V
- •Design Dive Speed V
- •Negative Load Factors
- •The Negative Stall
- •Manoeuvre Boundaries
- •Operational Speed Limits
- •Gust Loads
- •Effect of a Vertical Gust on the Load Factor
- •Effect of the Gust on Stalling
- •Operational Rough-air Speed (V
- •Landing Gear Speed Limitations
- •Flap Speed Limit
- •Aeroelasticity (Aeroelastic Coupling)
- •Flutter
- •Control Surface Flutter
- •Aileron Reversal
- •Questions
- •Answers
- •15 Windshear
- •Introduction (Ref: AIC 84/2008)
- •Microburst
- •Windshear Encounter during Approach
- •Effects of Windshear
- •“Typical” Recovery from Windshear
- •Windshear Reporting
- •Visual Clues
- •Conclusions
- •Questions
- •Answers
- •16 Propellers
- •Introduction
- •Definitions
- •Aerodynamic Forces on the Propeller
- •Thrust
- •Centrifugal Twisting Moment (CTM)
- •Propeller Efficiency
- •Variable Pitch Propellers
- •Power Absorption
- •Moments and Forces Generated by a Propeller
- •Effect of Atmospheric Conditions
- •Questions
- •Answers
- •17 Revision Questions
- •Questions
- •Answers
- •Explanations to Specimen Questions
- •Specimen Examination Paper
- •Answers to Specimen Exam Paper
- •Explanations to Specimen Exam Paper
- •18 Index
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Devices Lift High 8
Management of High Lift Devices
To take full advantage of the capabilities of flaps, the flight crew must properly manage their retraction and extension.
Flap Retraction afterTake-off
With reference to Figure 8.20, assume the aircraft has just taken off with flaps extended and is at point ‘A’ on the lift curve. If the flaps are retracted, with no change made to either angle of attack or IAS, the coefficient of lift will reduce to point ‘C’ and the aircraft will sink.
1.From point ‘A’ on the lift curve the aircraft should be accelerated to point ‘B’.
2.From point ‘B’, as the flaps are retracted the angle of attack should be increased to point ‘C’ to maintain the coefficient of lift constant.
The pilot should not retract the flaps until the aircraft has sufficient IAS. Of course, this same factor must be considered for any intermediate flap position between extended and retracted. (Refer to Page 76 for a review of the Interpretation of the Lift Curve if necessary.)
As the configuration is altered from the flaps down to the flaps up or “clean” configuration, three important changes take place:
•Changes of pressure distribution on the wing generate a nose-up pitching moment. But reduced wing downwash increasing the tailplane effective angle of attack generates a nosedown pitching moment. The resultant, actual, pitching moment experienced by the aircraft will depend upon which of these two pitching moments is dominant.
•With reference to Figure 8.21, the retraction of flaps (‘B’ to ‘C’) causes a reduction of drag coefficient. This drag reduction improves the acceleration of the aircraft.
•Flap retraction usually takes place in stages, and movement of the flaps between stages will take a finite period of time. It has been stated that as flaps are retracted, an increase in angle of attack is required to maintain the same lift coefficient.
If aircraft acceleration is low throughout the flap retraction speed range, the angle of attack must be increased an appreciable amount to prevent the aircraft from sinking. This situation is typical after take-off when gross weight and density altitude are high.
However, most modern jet transport aircraft have enough acceleration throughout the flap retraction speed range that the resultant rapid gain in airspeed requires a much less noticeable increase in angle of attack.
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High Lift Devices |
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CL |
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FLAPS EXTENDED |
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FLAPS RETRACTED |
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C |
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ANGLE OF ATTACK
Figure 8.20
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FLAPS EXTENDED |
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Figure 8.21
High Lift Devices 8
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Flap Extension Prior to Landing
With reference to Figure 8.22, assume the aircraft is in level flight in the terminal area prior to landing and is at point ‘A’ on the lift curve. If the flaps are extended, with no change made to angle of attack, the coefficient of lift will increase to point ‘C’ and the aircraft will gain altitude (balloon).
1.From point ‘A’, as the flaps are extended the angle of attack should be decreased to point ‘B’ to maintain the coefficient of lift constant.
2.From point ‘B’ on the lift curve the aircraft should be decelerated to point ‘C’.
(Refer to Page 76 for a review of the Interpretation of the Lift Curve if necessary.)
8
Devices Lift High |
CL |
C |
FLAPS EXTENDED |
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A |
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ANGLE OF ATTACK |
Figure 8.22 Deployment of flaps for landing
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Questions 8
Questions
1.With the flaps lowered, the stalling speed will:
a.increase.
b.decrease.
c.increase, but occur at a higher angle of attack.
d.remain the same.
2.When flaps are lowered the stalling angle of attack of the wing:
a.remains the same, but CLMAX increases.
b.increases and CLMAX increases.
c.decreases, but CLMAX increases.
d.decreases, but CLMAX remains the same.
3.With full flap, the maximum lift/drag ratio:
a.increases and the stalling angle increases.
b.decreases and the stalling speed decreases.
c.remains the same and the stalling angle remains the same.
d.remains the same and the stalling angle decreases.
4.When a leading edge slot is opened, the stalling speed will:
a.increase.
b.decrease.
c.remain the same but will occur at a higher angle of attack.
d.remain the same but will occur at a lower angle of attack.
5.Lowering the flaps during a landing approach:
a.increases the angle of descent without increasing the airspeed.
b.decreases the angle of descent without increasing power.
c.eliminates floating.
d.permits approaches at a higher indicated airspeed.
Questions 8
6.Lowering flaps sometimes produces a pitch moment change due to:
a.decrease of the angle of incidence.
b.movement of the centre of pressure.
c.movement of the centre of gravity.
d.increased angle of attack of the tailplane.
7.Which type of flap would give the greatest change in pitching moment?
a.Split.
b.Plain.
c.Fowler.
d.Plain slotted.
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A split flap is: |
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a flap divided into sections which open to form slots through the flap. |
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b. |
a flap manufactured in several sections to allow for wing flexing. |
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c. |
a flap which can move up or down from the neutral position. |
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d. |
a flap where the upper surface contour of the wing trailing edge is fixed and |
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only the lower surface contour is altered when the flaps are lowered. |
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9. |
If the flaps are lowered in flight, with the airspeed kept constant, to maintain level |
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flight the angle of attack: |
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must be reduced. |
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must be increased. |
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c. |
must be kept constant but power must be increased. |
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must be kept constant and power required will be constant. |
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10. |
If flaps are lowered during the take off run: |
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the lift would not change until the aircraft is airborne. |
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the lift would increase when the flaps are lowered. |
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the lift would decrease. |
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the acceleration would increase. |
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11. |
When flaps are lowered the spanwise flow on the upper surface of the wing: |
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does not change. |
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increase towards the tip. |
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increases towards the root. |
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increases in speed but has no change of direction. |
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12. |
If a landing is to be made without flaps, the landing speed must be: |
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reduced. |
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increased. |
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c. |
the same as for a landing with flaps. |
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d. |
the same as for a landing with flaps but with a steeper approach. |
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13. |
With reference to Annex A , the type of flap illustrated is a: |
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slotted Krueger flap. |
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b. |
slotted variable camber flap. |
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c. |
slotted slat. |
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d. |
slotted Fowler flap. |
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14. |
With reference to Annex B , the type of flap illustrated is a: |
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slat. |
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Fowler flap. |
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c. |
Krueger flap. |
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d. |
variable camber flap. |
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