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Questions and Answers
Which force opposes lift and is caused by the downward pull of gravity?
Which force opposes lift and is caused by the downward pull of gravity?
What is the force that propels the helicopter through the air?
What is the force that propels the helicopter through the air?
What is drag?
What is drag?
Which component of lift is responsible for induced drag?
Which component of lift is responsible for induced drag?
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What happens to induced drag as airspeed increases?
What happens to induced drag as airspeed increases?
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What causes the formation of stronger vortices and an increase in induced drag?
What causes the formation of stronger vortices and an increase in induced drag?
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Which of the following is NOT a type of drag in a helicopter?
Which of the following is NOT a type of drag in a helicopter?
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What is the load factor of a helicopter in steady-state flight?
What is the load factor of a helicopter in steady-state flight?
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What is the solidity ratio of a rotor system?
What is the solidity ratio of a rotor system?
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What is the main factor that determines the majority of lift in a helicopter?
What is the main factor that determines the majority of lift in a helicopter?
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Which one of the following is true about the center of pressure on an airfoil?
Which one of the following is true about the center of pressure on an airfoil?
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What is the purpose of bending the trailing edge of an asymmetrical rotor blade?
What is the purpose of bending the trailing edge of an asymmetrical rotor blade?
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What is the span of an airfoil?
What is the span of an airfoil?
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What is the chord line of an airfoil?
What is the chord line of an airfoil?
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Which of the following statements is true about the angle of attack?
Which of the following statements is true about the angle of attack?
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What is the Magnus Effect?
What is the Magnus Effect?
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What is Bernoulli's Principle?
What is Bernoulli's Principle?
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What is the relationship between the angle of attack and the production of lift?
What is the relationship between the angle of attack and the production of lift?
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Due to the downward deflection of the airstream near the rotor blade, the blade operates in an average relative wind that is inclined ______ and rearward near the blade.
Due to the downward deflection of the airstream near the rotor blade, the blade operates in an average relative wind that is inclined ______ and rearward near the blade.
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The lift produced by the blade is perpendicular to the relative wind, therefore the lift is inclined ______ by the same amount.
The lift produced by the blade is perpendicular to the relative wind, therefore the lift is inclined ______ by the same amount.
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The component of lift that is acting in a rearward direction is ______ drag.
The component of lift that is acting in a rearward direction is ______ drag.
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As the air pressure differential increases with an increase in angle of attack, stronger vortices form, and ______ drag increases.
As the air pressure differential increases with an increase in angle of attack, stronger vortices form, and ______ drag increases.
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Induced drag is the major cause of drag at ______ airspeeds.
Induced drag is the major cause of drag at ______ airspeeds.
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True or false: The downward deflection of the airstream near the rotor blade causes the blade to operate in an average relative wind that is inclined downward and rearward near the blade.
True or false: The downward deflection of the airstream near the rotor blade causes the blade to operate in an average relative wind that is inclined downward and rearward near the blade.
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True or false: As the air pressure differential increases with an increase in angle of attack, stronger vortices form, and induced drag decreases.
True or false: As the air pressure differential increases with an increase in angle of attack, stronger vortices form, and induced drag decreases.
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True or false: Induced drag is the major cause of drag at higher airspeeds.
True or false: Induced drag is the major cause of drag at higher airspeeds.
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Study Notes
Forces in Helicopter Flight
- Weight is the force opposing lift, caused by gravitational pull.
- Thrust is the force that propels the helicopter through the air.
Types of Drag
- Drag is the aerodynamic resistance encountered by an object moving through air.
- Induced Drag results from the lift force, specifically linked to the component of lift that generates this drag.
- Induced drag increases with stronger air vortices created during flight.
Airspeed and Drag
- As airspeed increases, induced drag decreases.
- Stronger vortices and increased induced drag occur at higher angles of attack.
Helicopter Specifications
- Load Factor in steady-state flight refers to the amount of lift compared to weight, typically around 1:1 during normal flight conditions.
- Solidity Ratio describes the ratio of the total rotor blade area to the total rotor disk area.
- Lift in helicopters is primarily determined by the rotor blades' angle of attack and design.
Airfoil Characteristics
- The center of pressure on an airfoil is the point where lift can be considered to act; it shifts with changes in the angle of attack.
- Bending the trailing edge of an asymmetrical rotor blade helps optimize lift and control characteristics.
- The span of an airfoil is its length from tip to tip, while the chord line is the straight line connecting the leading edge to the trailing edge of the airfoil.
Aerodynamic Principles
- The angle of attack significantly impacts lift production; it represents the angle between the airfoil’s chord line and the oncoming airflow.
- The Magnus Effect describes the phenomenon where a rotating body in a fluid experiences a lift force perpendicular to the direction of motion and rotation.
- Bernoulli's Principle explains that an increase in the speed of a fluid occurs simultaneously with a decrease in pressure.
Summary of Lift and Drag Components
- The downward deflection of the airstream results in the rotor blade operating at an average relative wind inclined downward and rearward.
- Lift is produced perpendicular to the relative wind, thus also inclined similarly.
- The rearward acting component of lift contributes to induced drag.
- Increased air pressure differential with higher angle of attack causes larger vortices, thus elevating induced drag.
True or False Statements
- True: The downward deflection of the airstream aligns the blade's operation angle downward and rearward.
- False: An increase in angle of attack results in increased induced drag, not a decrease.
- False: Induced drag is less significant at higher airspeeds, being more dominant at lower speeds.
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Description
Test your knowledge on the effects of increasing the angle of attack on lift and stalling with this quiz. Learn about the critical angle of attack and how it determines lift production. Explore the progression of the separation point on an airfoil as the angle of attack is increased.
