- •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
6 Questions
Questions 6
Questions
1.What is the effect on total drag of an aircraft if the airspeed decreases in level flight below that speed for maximum L/D?
a.Drag increases because of increased induced drag.
b.Drag decreases because of lower induced drag.
c.Drag increases because of increased parasite drag.
d.Drag decreases because of lower parasite drag.
2.By changing the angle of attack of a wing, the pilot can control the aeroplane’s:
a.lift and airspeed, but not drag.
b.lift, gross weight, and drag.
c.lift, airspeed, and drag.
d.lift and drag, but not airspeed.
3.What is the relationship between induced and parasite drag when the gross weight is increased?
a.Parasite drag increases more than induced drag.
b.Induced drag increases more than parasite drag.
c.Both parasite and induced drag are equally increased.
d.Both parasite and induced drag are equally decreased.
4.In theory, if the airspeed of an aeroplane is doubled while in level flight, parasite drag will become:
a.twice as great.
b.half as great.
c.four times greater.
d.one quarter as much.
5.As airspeed decreases in level flight below that speed for maximum lift/drag ratio, total drag of an aeroplane:
a.decreases because of lower parasite drag.
b.increases because of increased parasite drag.
c.increases because of increased induced drag.
d.decreases because of lower induced drag.
6.(Refer to annex ‘A’) At the airspeed represented by point B, in steady flight, the aeroplane will:
a.have its maximum L/D ratio.
b.have its minimum L/D ratio.
c.be developing its maximum coefficient of lift.
d.be developing its minimum coefficient of drag.
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7. |
Which statement is true relative to changing angle of attack? |
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A decrease in angle of attack will increase pressure below the wing, and |
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decrease drag. |
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b. |
An increase in angle of attack will decrease pressure below the wing, and |
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increase drag. |
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c. |
An increase in angle of attack will increase drag. |
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d. |
A decrease in angle of attack will decrease pressure below the wing and |
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increase drag. |
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8. |
On a wing, the force of lift acts perpendicular to, and the force of drag acts parallel |
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to the: |
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flight path. |
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b. |
longitudinal axis. |
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c. |
chord line. |
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d. |
longitudinal datum. |
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9. |
That portion of the aircraft’s total drag created by the production of lift is called: |
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a. |
induced drag, and is greatly affected by changes in airspeed. |
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b. |
induced drag, and is not affected by changes in airspeed. |
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c. |
parasite drag, and is greatly affected by changes in airspeed. |
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d. |
parasite drag, which is inversely proportional to the square of the airspeed. |
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10. |
The best L/D ratio of an aircraft occurs when parasite drag is: |
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a minimum. |
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b. |
less than induced drag. |
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c. |
greater than induced drag. |
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d. |
equal to induced drag. |
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11. |
An aircraft has a L/D ratio of 15:1 at 50 kt in calm air. What would the L/D ratio be |
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with a direct headwind of 25 kt? |
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a. |
30 : 1 |
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b. |
15 : 1 |
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c. |
25 : 1 |
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d. |
7.5 : 1 |
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12. |
Which is true regarding aerodynamic drag? |
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Induced drag is a by product of lift and is greatly affected by changes in |
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airspeed. |
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b. |
All aerodynamic drag is created entirely by the production of lift. |
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c. |
Induced drag is created entirely by air resistance. |
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d. |
Parasite drag is a by-product of lift. |
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13. |
At a given True Airspeed, what effect will increased air density have on the lift and |
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drag of an aircraft? |
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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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14. |
If the Indicated Airspeed of an aircraft is increased from 50 kt to 100 kt, parasite |
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drag will be: |
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four times greater. |
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b. |
six times greater. |
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c. |
two times greater. |
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d. |
one quarter as much. |
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15. |
If the Indicated Airspeed of an aircraft is decreased from 100 kt to 50 kt, induced |
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drag will be: |
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two times greater. |
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b. |
four times greater. |
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c. |
half as much. |
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d. |
one quarter as much. |
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16. |
The best L/D ratio of an aircraft in a given configuration is a value that: |
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varies with Indicated Airspeed. |
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b. |
varies depending upon the weight being carried. |
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c. |
varies with air density. |
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d. |
remains constant regardless of Indicated Airspeed changes. |
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17. |
The tendency of an aircraft to develop forces which restore it to its original |
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condition, when disturbed from a condition of steady flight, is known as: |
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manoeuvrability. |
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b. |
controllability. |
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c. |
stability. |
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d. |
instability. |
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18. |
As Indicated Airspeed increases in level flight, the total drag of an aircraft becomes |
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greater than the total drag produced at the maximum lift/drag speed because of |
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the: |
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decrease in induced drag only. |
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b. |
increase in induced drag. |
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c. |
increase in parasite drag. |
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d. |
decrease in parasite drag only. |
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19. |
The resistance, or skin friction, due to the viscosity of the air as it passes along the |
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surface of a wing is a type of: |
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induced drag. |
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b. |
form drag. |
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c. |
parasite drag. |
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d. |
interference drag. |
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20. |
Which relationship is correct when comparing drag and airspeed? |
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Parasite drag varies inversely as the square of the airspeed. |
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b. |
Induced drag increases as the square of the airspeed. |
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c. |
Parasite drag increases as the square of the lift coefficient divided by the |
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aspect ratio. |
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d. |
Induced drag varies inversely as the square of the airspeed. |
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6 |
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21. |
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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decrease, and parasite drag will decrease. |
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b. |
increase, and induced drag will decrease. |
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c. |
decrease, and parasite drag will increase. |
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d. |
increase and induced drag will increase. |
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22. |
Which statement is true regarding aeroplane flight at L/Dmax? |
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Any angle of attack other than that for L/Dmax increases parasite drag. |
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b. |
Any angle of attack other than that for L/Dmax increases the lift/drag ratio. |
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c. |
Any angle of attack other than that for L/Dmax increases total drag for a |
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given aeroplane’s lift. |
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d. |
Any angle of attack other than that for L/Dmax increases the lift and reduces |
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the drag. |
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23. |
Aspect ratio of a wing is defined as the ratio of the: |
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square of the chord to the wingspan. |
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wingspan to the wing root. |
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c. |
area squared to the chord. |
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d. |
wingspan to the mean chord. |
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24. |
A wing with a very high aspect ratio (in comparison with a low aspect ratio wing) |
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will have: |
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poor control qualities at low airspeeds. |
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increased drag at high angles of attack. |
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c. |
a lower stall speed. |
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d. |
reduced bending moment on its attachment points. |
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25. |
At a constant velocity in airflow, a high aspect ratio wing will have (in comparison |
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with a low aspect ratio wing): |
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increased drag, especially at a low angle of attack. |
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b. |
decreased drag, especially at a high angle of attack. |
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c. |
increased drag, especially at a high angle of attack. |
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d. |
decreased drag, especially at low angles of attack. |
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26. |
(Refer to annex ‘B’) Which aircraft has the highest aspect ratio? |
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3. |
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b. |
4. |
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c. |
2. |
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d. |
1. |
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27. |
(Refer to annex ‘B’) Which aircraft has the lowest aspect ratio? |
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4. |
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b. |
2. |
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c. |
3. |
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d. |
1. |
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28. |
(Refer to annex ‘B’) Consider only aspect ratio (other factors remain constant). |
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Which aircraft will generate greatest lift? |
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1. |
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b. |
2. |
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c. |
3. |
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d. |
4. |
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29. |
(Refer to annex ‘B’) Consider only aspect ratio (other factors remain constant). |
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Which aircraft will generate greatest drag? |
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1. |
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4. |
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c. |
3. |
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d. |
2. |
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30. |
What happens to total drag when accelerating from CLMAX to maximum speed? |
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Increases. |
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Increases then decreases. |
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Decreases. |
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Decreases then increases. |
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31. |
(Refer to annex ‘C’), the whole aircraft CL against CD polar. Point ‘B’ represents: |
1.Best Lift/Drag ratio.
2 . |
The critical angle of attack. |
3.Recommended approach speed.
4.Never exceed speed (VNE ).
a.1 and 2.
b.1 only.
c.2 and 3.
d.4 only.
32.If the Indicated Airspeed of an aircraft in level flight is increased from 100 kt to
200kt, by what factor will (i) TAS (ii) CDi (iii) Di change?
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(ii) |
(iii) |
a. |
2 |
1/4 |
1/16 |
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0 |
4 |
16 |
c. |
4 |
1/16 |
1/4 |
d. |
2 |
1/16 |
1/4 |
138
Questions 6
Annex A
Questions 6
Annex B
Aircraft 1. Span 22.5 metres
Chord 4 metres
Aircraft 2. Wing Area 90 square metres
Span 45 metres
Aircraft 3. Span 30 metres
Chord 3 metres
Aircraft 4. Wing Area 90 square metres
Span 40 metres
139