- •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
5 Lift
Answers from page 78
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CAMBERED |
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WITH 12% THICKNESS |
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CAMBER GIVES |
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INCREASE IN CLMAX |
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Lift |
COEFFICIENT |
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SYMMETRICAL |
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LIFT |
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WITH 12% THICKNESS |
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SECTION |
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GREATER THICKNESS |
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GIVES 70% INCREASE |
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IN CLMAX |
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SYMMETRICAL |
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WITH 6% THICKNESS |
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SECTION ANGLE OF ATTACK (DEGREES) |
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Figure 5.28 |
a. |
Why does the cambered aerofoil section have a significantly higher CLMAX? |
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When compared to a symmetrical section of the same thickness: at approximately |
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the same stall angle, the cross-sectional area of the streamtube over the top surface |
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is smaller with a more gradual section change. This allows greater acceleration of |
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the air over the top surface, and a bigger pressure differential. |
b.For the same angle of attack, why do the symmetrical aerofoil sections generate less lift than the cambered aerofoil section? Angle of attack is the angle between the chord line and the relative airflow. At the same angle of attack, the cross-sectional area of the symmetrical section upper surface streamtube is larger.
c.Why does the cambered aerofoil section of 12% thickness generate a small amount of lift at slightly negative angles of attack? At small negative angles of attack, a cambered aerofoil is still providing a reduced cross-sectional area streamtube over the top surface, generating a small pressure differential.
d.For a given angle of attack, the symmetrical aerofoil section of 6% thickness generates the smallest amount of lift. In what way can this be a favourable characteristic?
At the high speeds at which modern high speed jet transport aircraft operate, a thin wing can generate the required lift force with minimum drag caused by the formation of shock waves. (This will be fully explained in later chapters).
e.What are the disadvantages of the symmetrical aerofoil section of 6% thickness?
It will give a high minimum speed, requiring complex high lift devices to enable the aircraft to use existing runways.
100
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5 |
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1. |
To maintain altitude, what must be done as Indicated Airspeed (IAS) is reduced? |
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Decrease angle of attack to reduce the drag. |
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b. |
Increase angle of attack to maintain the correct lift force. |
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c. |
Deploy the speed brakes to increase drag. |
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d. |
Reduce thrust. |
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2. |
If more lift force is required because of greater operating weight, what must be |
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done to fly at the angle of attack which corresponds to CLMAX? |
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a. |
Increase the angle of attack. |
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b. |
Nothing, the angle of attack for CLMAX is constant. |
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c. |
It is impossible to fly at the angle of attack that corresponds to CLMAX. |
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d. |
Increase the Indicated Airspeed (IAS). |
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3. |
Which of the following statements is correct? |
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1. |
To generate a constant lift force, any adjustment in IAS must be |
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accompanied by a change in angle of attack. |
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2. |
For a constant lift force, each IAS requires a specific angle of attack. |
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3. |
Minimum IAS is determined by CLMAX. |
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4. |
The greater the operating weight, the higher the minimum IAS. |
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a. |
1, 2 and 4. |
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b. |
4 only. |
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c. |
2, 3 and 4. |
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d. |
1, 2, 3 and 4. |
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4. |
What effect does landing at high altitude airports have on ground speed with |
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comparable conditions relative to temperature, wind and aeroplane weight? |
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Higher than at low altitude. |
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b. |
The same as at low altitude. |
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c. |
Lower than at low altitude. |
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d. |
Dynamic pressure will be the same at any altitude. |
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5. |
What flight condition should be expected when an aircraft leaves ground effect? |
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a. |
A decrease in parasite drag permitting a lower angle of attack. |
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b. |
An increase in induced drag and a requirement for a higher angle of attack. |
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c. |
An increase in dynamic stability. |
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d. |
A decrease in induced drag requiring a smaller angle of attack. |
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6. |
If the angle of attack and other factors remain constant and airspeed is doubled, |
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lift will be: |
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two times greater. |
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b. |
four times greater. |
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c. |
the same. |
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d. |
one quarter. |
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7. |
What true airspeed and angle of attack should be used to generate the same |
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amount of lift as altitude is increased? |
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A higher true airspeed for any given angle of attack. |
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b. |
The same true airspeed and angle of attack. |
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c. |
A lower true airspeed and higher angle of attack. |
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d. |
A constant angle of attack and true airspeed. |
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8. |
How can an aeroplane produce the same lift in ground effect as when out of |
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ground effect? |
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b. |
A higher angle of attack. |
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a. |
A lower angle of attack. |
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c. |
The same angle of attack. |
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d. |
The same angle of attack, but a lower IAS. |
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9. |
By changing the angle of attack of a wing, the pilot can control the aeroplane’s: |
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lift and airspeed, but not drag. |
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b. |
lift, gross weight, and drag. |
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c. |
lift, airspeed, and drag. |
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d. |
lift and drag, but not airspeed. |
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10. |
Which flight conditions of a large jet aeroplane create the most severe flight hazard |
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by generating wing tip vortices of the greatest strength? |
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a. |
Heavy, slow, gear and flaps up. |
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b. |
Heavy, fast, gear and flaps down. |
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c. |
Heavy, slow, gear and flaps down. |
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d. |
Weight, gear and flaps make no difference. |
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11. |
Hazardous vortex turbulence that might be encountered behind large aircraft is |
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created only when that aircraft is: |
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using high power settings. |
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b. |
operating at high airspeeds. |
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c. |
developing lift. |
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d. |
operating at high altitude. |
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12. |
Wing tip vortices created by large aircraft tend to: |
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rise from the surface to traffic pattern altitude. |
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sink below the aircraft generating the turbulence. |
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c. |
accumulate and remain for a period of time at the point where the takeoff roll |
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began. |
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d. |
dissipate very slowly when the surface wind is strong. |
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13. |
How does the wake turbulence vortex circulate around each wing tip, when |
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viewed from the rear? |
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a. |
Inward, upward, and around the wing tip. |
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b. |
Counterclockwise. |
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c. |
Outward, upward, and around the wing tip. |
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d. |
Outward, downward and around the wing tip. |
102
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Questions |
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5 |
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14. |
Which statement is true concerning the wake turbulence produced by a large |
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transport aircraft? |
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Wake turbulence behind a propeller driven aircraft is negligible because jet |
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engine thrust is a necessary factor in the formation of vortices. |
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b. |
Vortices can be avoided by flying 300 ft below and behind the flight path of |
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the generating aircraft. |
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c. |
The vortex characteristics of any given aircraft may be altered by extending |
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the flaps or changing the speed. |
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15. |
d. |
Vortices can be avoided by flying downwind of, and below the flight path of |
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Questions |
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What effect would a light crosswind have on the wing tip vortices generated by a |
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the generating aircraft. |
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large aeroplane that has just taken off? |
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a. |
The downwind vortex will tend to remain on the runway longer than the |
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upwind vortex. |
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b. |
A crosswind will rapidly dissipate the strength of both vortices. |
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c. |
A crosswind will move both vortices clear of the runway. |
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d. |
The upwind vortex will tend to remain on the runway longer than the |
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downwind vortex. |
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16. |
To avoid the wing tip vortices of a departing jet aeroplane during take-off, the pilot |
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should: |
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remain below the flight path of the jet aeroplane. |
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b. |
climb above and stay upwind of the jet aeroplane’s flight path. |
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c. |
lift off at a point well past the jet aeroplane’s flight path. |
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d. |
remain below and downwind of the jet aeroplane’s flight path. |
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17. |
What wind condition prolongs the hazards of wake turbulence on a landing |
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runway for the longest period of time? |
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a. |
Light quartering headwind. |
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b. |
Light quartering tailwind. |
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c. |
Direct tailwind. |
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d. |
Strong, direct crosswind. |
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18. |
If you take off behind a heavy jet that has just landed, you should plan to lift off: |
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a. |
prior to the point where the jet touched down. |
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b. |
at the point where the jet touched down and on the upwind edge of the |
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runway. |
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c. |
before the point where the jet touched down and on the downwind edge of |
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the runway. |
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d. |
beyond the point where the jet touched down. |
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19. |
The adverse effects of ice, snow or frost on aircraft performance and flight |
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characteristics include decreased lift and: |
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a. |
increased thrust. |
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b. |
a decreased stall speed. |
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c. |
an increased stall speed. |
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d. |
an aircraft will always stall at the same indicated airspeed. |
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103
5 Questions
Questions 5
20.Lift on a wing is most properly defined as the:
a.differential pressure acting perpendicular to the chord of the wing.
b.force acting perpendicular to the relative wind.
c.reduced pressure resulting from a laminar flow over the upper camber of an aerofoil, which acts perpendicular to the mean camber.
d.force acting parallel with the relative wind and in the opposite direction.
21.Which statement is true relative to changing angle of attack?
a.A decrease in angle of attack will increase pressure below the wing, and decrease drag.
b.An increase in angle of attack will decrease pressure below the wing, and increase drag.
c.An increase in angle of attack will increase drag.
d.An increase in angle of attack will decrease the lift coefficient.
22.The angle of attack of a wing directly controls the:
a.angle of incidence of the wing.
b.distribution of pressures acting on the wing.
c.amount of airflow above and below the wing.
d.dynamic pressure acting in the airflow.
23.In theory, if the angle of attack and other factors remain constant and the airspeed is doubled, the lift produced at the higher speed will be:
a.the same as at the lower speed.
b.two times greater than at the lower speed.
c.four times greater than at the lower speed.
d.one quarter as much.
24.An aircraft wing is designed to produce lift resulting from a difference in the:
a.negative air pressure below and a vacuum above the wing’s surface.
b.vacuum below the wing’s surface and greater air pressure above the wing’s surface.
c.higher air pressure below the wing’s surface and lower air pressure above the wing’s surface.
d.higher pressure at the leading edge than at the trailing edge.
25.On a wing, the force of lift acts perpendicular to, and the force of drag acts parallel to the:
a.camber line.
b.longitudinal axis.
c.chord line.
d.flight path.
26.Which statement is true, regarding the opposing forces acting on an aeroplane in steady state level flight?
a.Thrust is greater than drag and weight and lift are equal.
b.These forces are equal.
c.Thrust is greater than drag and lift is greater than weight.
d.Thrust is slightly greater than Lift, but the drag and weight are equal.
104
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Questions |
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5 |
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27. |
At higher elevation airports the pilot should know that indicated airspeed: |
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will be unchanged, but ground speed will be faster. |
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b. |
will be higher, but ground speed will be unchanged. |
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c. |
should be increased to compensate for the thinner air. |
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d. |
should be higher to obtain a higher landing speed. |
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28. |
An aeroplane leaving ground effect will: |
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5 |
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experience a reduction in ground friction and require a slight power |
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c. |
experience a reduction in induced drag and require a smaller angle of attack |
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reduction. |
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b. |
require a lower angle of attack to maintain the same lift coefficient. |
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d. |
experience an increase in induced drag and require more thrust. |
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29. |
If the same angle of attack is maintained in ground effect as when out of ground |
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effect, lift will: |
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increase, and induced drag will increase. |
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b. |
increase, and induced drag will decrease. |
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c. |
decrease, and induced drag will increase. |
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d. |
decrease and induced drag will decrease. |
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30. |
Which is true regarding the force of lift in steady, unaccelerated flight? |
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a. |
There is a corresponding indicated airspeed required for every angle of attack |
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to generate sufficient lift to maintain altitude. |
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b. |
An aerofoil will always stall at the same indicated airspeed; therefore, an |
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increase in weight will require an increase in speed to generate sufficient lift to |
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maintain altitude. |
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c. |
At lower airspeeds the angle of attack must be less to generate sufficient lift |
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to maintain altitude. |
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d. |
The lift force must be exactly equal to the drag force. |
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31. |
At a given Indicated Airspeed, what effect will an increase in air density have on lift |
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and drag? |
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Lift will increase but drag will decrease. |
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b. |
Lift and drag will increase. |
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c. |
Lift and drag will decrease. |
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d. |
Lift and drag will remain the same. |
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32. |
If the angle of attack is increased beyond the critical angle of attack, the wing will |
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no longer produce sufficient lift to support the weight of the aircraft: |
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unless the airspeed is greater than the normal stall speed. |
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b. |
regardless of airspeed or pitch attitude. |
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c. |
unless the pitch attitude is on or below the natural horizon. |
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d. |
in which case, the control column should be pulled back immediately. |
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105
5 Questions
Questions 5
33.Given that:
Aircraft A.
Wingspan: 51 m
Average wing chord: 4 m
Aircraft B.
Wingspan: 48 m
Average wing chord: 3.5 m
Determine the correct aspect ratio and wing area:
a.aircraft A has an aspect ratio of 13.7, and has a larger wing area than aircraft B.
b.aircraft B has an aspect ratio of 13.7, and has a smaller wing area than aircraft A.
c.aircraft B has an aspect ratio of 12.75, and has a smaller wing area than aircraft A.
d.aircraft A has an aspect ratio of 12.75, and has a smaller wing area than aircraft B.
34.Aspect ratio of the wing is defined as the ratio of the:
a.wingspan to the wing root.
b.square of the chord to the wingspan.
c.wingspan to the average chord.
d.square of the wing area to the span.
35.What changes to aircraft control must be made to maintain altitude while the airspeed is being decreased?
a.Increase the angle of attack to compensate for the decreasing dynamic pressure.
b.Maintain a constant angle of attack until the desired airspeed is reached, then increase the angle of attack.
c.Increase angle of attack to produce more lift than weight.
d.Decrease the angle of attack to compensate for the decrease in drag.
36.Take-off from an airfield with a low density altitude will result in:
a.a longer take-off run.
b.a higher than standard IAS before lift off.
c.a higher TAS for the same lift off IAS.
d.a shorter take-off run because of the lower TAS required for the same IAS.
106
Questions 5
Questions 5
107