- •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
Questions
Questions
1.Identify which of the following is the correct formula for Mach number:
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TAS |
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IAS |
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M = |
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TAS = |
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d. |
M = TAS × a |
2.What is the result of a shock induced separation of airflow occurring symmetrically near the wing root of a sweptwing aircraft?
a.A severe nose-down pitching moment or “tuck under”.
b.A high speed stall and sudden pitch up.
c.Severe porpoising.
d.Pitch-up.
3.Mach number is:
a.the ratio of the aircraft’s TAS to the speed of sound at sea level.
b.the ratio of the aircraft’s TAS to the speed of sound at the same atmospheric conditions.
c.the ratio of the aircraft’s IAS to the speed of sound at the same atmospheric conditions.
d.the speed of sound.
4.For an aircraft climbing at a constant IAS the Mach number will:
a.increase.
b.decrease.
c.remain constant.
d.initially show an increase, then decrease.
5.The term ‘transonic speed’ for an aircraft means:
a.speeds where the airflow is completely subsonic.
b.speeds where the airflow is completely supersonic.
c.speeds where the airflow is partly subsonic and partly supersonic.
d.speeds between M 0.4 and M 1.0
6.At M 0.8 a wing has supersonic flow between 20% chord and 60% chord. There will be a shock wave:
a.at 20% chord only.
b.at 20% chord and 60% chord.
c.at 60% chord only.
d.forward of 20% chord.
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13 Questions
7. |
As air flows through a shock wave: |
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static pressure increases, density decreases, temperature increases. |
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static pressure increases, density increases, temperature increases. |
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c. |
static pressure decreases, density increases, temperature decreases. |
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d. |
static pressure decreases, density decreases, temperature decreases. |
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8. |
For a wing section of given thickness, the critical Mach number: |
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will decrease if angle of attack is increased. |
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will increase if angle of attack is increased. |
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c. |
will not change with changes of angle of attack. |
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d. |
is only influenced by changes in temperature. |
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9. |
At speeds above the critical Mach number, the lift coefficient: |
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will start to increase. |
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will start to decrease. |
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will remain constant. |
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d. |
is directly proportional to the Mach number. |
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10. |
As air flows through a shock wave: |
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its speed increases. |
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its speed decreases. |
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c. |
its speed remains the same. |
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d. |
it changes direction to flow parallel with the Mach cone. |
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11. |
If an aeroplane accelerates above the critical Mach number, the first high Mach |
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number characteristic it will usually experience is: |
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a nose-up pitch or “Shock Stall”. |
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b. |
a violent and sustained oscillation in pitch (porpoising). |
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c. |
Dutch roll and/or spiral instability. |
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d. |
a nose-down pitching moment (Mach, or high speed tuck). |
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12. |
High speed buffet is caused by: |
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the shock waves striking the tail. |
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b. |
the high speed airflow striking the leading edge of the wing. |
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wing flutter caused by the interaction of the bottom and top surface shock |
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waves. |
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d. |
the airflow being detached by the shock wave and the turbulent flow striking |
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the tail. |
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13. |
The “area rule” applied to high speed aircraft requires: |
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that the cross-sectional area shall be as small as possible. |
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that the variation of cross-sectional area along the length of the aircraft |
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follows a smooth pattern. |
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that the maximum cross-sectional area of the fuselage should occur at the |
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wing root. |
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d. |
that the fuselage and the wing area be of a ratio of 3 : 1. |
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14. |
An all moving tailplane is used in preference to elevators on high speed aircraft: |
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because the effect of the elevator is reversed above the critical Mach number. |
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because shock wave formation on the elevator causes excessive stick forces. |
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because shock wave formation ahead of the elevator causes separation and |
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loss of elevator effectiveness. |
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because it would be physically impossible for a pilot to control the aircraft in |
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pitch with a conventional tailplane and elevator configuration. |
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15. |
Mach Trim is a device which: |
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moves the centre of gravity to maintain stable lateral stick forces in the |
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transonic region. |
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automatically compensates for pitch changes while flying in the transonic |
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speed region. |
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prevents the aircraft from exceeding its critical Mach number. |
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switches out the trim control to prevent damage in the transonic region. |
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16. |
What is the movement of the centre of pressure when the wing tips of a |
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sweptwing aeroplane are shock stalled first? |
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Outward and forward. |
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b. |
Inward and aft. |
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c. |
Outward and aft. |
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d. |
Inward and forward. |
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17. |
The airflow behind a normal shock wave will: |
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always be subsonic and in the same direction as the original airflow. |
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b. |
always be supersonic and in the same direction as the original airflow. |
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may be subsonic or supersonic. |
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always be subsonic and will be deflected from the direction of the original |
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airflow. |
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18. |
As airflow passes through a normal shock wave, which of the following changes in |
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static pressure (i), density (ii), and Mach number (iii) will occur? |
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(i) |
(ii) |
(iii) |
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a. |
decrease |
increase |
< 1.0 |
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b. |
increase |
decrease |
< 1.0 |
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c. |
increase |
decrease |
> 1.0 or < 1.0 |
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d. |
increase |
increase |
< 1.0 |
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19.An aerofoil travelling at supersonic speed will:
a.have its centre of pressure at 50 % chord.
b.have its centre of pressure at 25% chord.
c.give a larger proportion of lift from the lower surface than from the upper surface, and have its centre of pressure at 50 % chord.
d.give approximately equal lift from the upper and lower surfaces, and have its aerodynamic centre at 50% chord.
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13 Questions
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20. |
A bow wave is: |
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a shock wave which forms on the nose of the aircraft at MCRIT. |
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the shape formed when the shock waves on the upper and lower wing surface |
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meet at the trailing edge. |
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c. |
a shock wave that forms immediately ahead of an aircraft which is travelling |
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faster than the speed of sound. |
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the shape of a shock wave when viewed vertically. |
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21. |
When an aircraft is flying at supersonic speed, where will the area of influence of |
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any pressure disturbance due to the presence of the aircraft be located? |
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Within the Mach Cone. |
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In front of the Mach Cone. |
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In front of the bow wave. |
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d. |
In front of the Mach Cone only when the speed exceeds M 1.0 |
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22. |
The temperature of the airflow as it passes through an expansion wave: |
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increases. |
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decreases. |
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c. |
is inversely proportional to the square root of the Mach number. |
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d. |
remains the same. |
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23. |
The influence of weight (wing loading) on the formation of shock waves is: |
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low wing loading will give a higher MCRITCRIT. |
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a higher wing loading will increase M . |
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wing loading does not influence MCRIT. |
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wing loading and MCRIT are directly proportional. |
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24. |
What influence does an oblique shock wave have on the streamline pattern (i), |
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variation of pressure (ii), temperature(iii), density (iv) and velocity (v)? |
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(i) |
(ii) |
(iii) |
(iv) |
(v) |
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a. |
parallel to surface |
increase |
increase |
increase |
decrease |
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b. |
normal to wave |
decrease |
decrease |
decrease |
increase |
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c. |
parallel to wave |
decrease |
decrease |
decrease |
increase |
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d. |
parallel to chord |
increase |
decrease |
increase |
decrease |
25.Wave drag is caused by:
a.shock waves interfering with the smooth airflow into the engine intakes.
b.flying faster than MMO.
c.the conversion of mechanical energy into thermal energy by the shock wave.
d.flying faster than VMO.
26.What is the effect of a shock wave on control surface efficiency?
a.Increase in efficiency, due to increased velocity.
b.Increase in efficiency, due to the extra leverage caused by the shock wave.
c.Decrease in efficiency, due to the bow wave.
d.Loss of efficiency, due to control deflection no longer modifying the total flow over the wing.
454
Questions 13
27.At what speed does an oblique shock wave move over the earth surface?
a.Aircraft ground speed.
b.The TAS of the aircraft plus the wind speed.
c.The TAS of the aircraft less the wind speed.
d.The TAS relative to the speed of sound at sea level.
Questions 13
455