Questions and Answers
What is the primary function of an airfoil?
What is the equation for thrust?
Thrust (T) = mass flow rate x velocity change
The shape of an airfoil creates a difference in ___________ between the upper and lower surfaces, resulting in lift.
pressure
What is the primary factor that affects drag?
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Thrust is the backward force that opposes an aircraft's motion.
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Lift is the backward force that opposes an aircraft's motion.
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What is the definition of Bernoulli's Principle?
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Match the following forces with their definitions:
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The equation for lift is given by L = 0.5 x ___________ x velocity^2 x wing area x lift coefficient.
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Rotary wings are used in wind turbines to generate lift.
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Study Notes
Airfoil
- Definition: A curved surface used to produce lift when air flows over it
- Characteristics:
- Cambered upper surface (curved)
- Flat lower surface
- Angled to oncoming airflow (angle of attack)
- Function: Converts airflow into an upward force (lift) and a forward force (thrust)
Thrust
- Definition: The forward force that propels an aircraft through the air
- Generation:
- Produced by the aircraft's engines (jet or propeller)
- Created by the acceleration of air rearward
- Equation: Thrust (T) = mass flow rate x velocity change
Drag
- Definition: The backward force that opposes an aircraft's motion
- Types:
- Friction drag (skin friction, form drag)
- Induced drag (created by wingtip vortices)
- Factors affecting drag:
- Air density
- Velocity
- Shape and size of the aircraft
- Surface roughness
Lift
- Definition: The upward force that opposes an aircraft's weight
- Generation:
- Created by the shape of the airfoil
- Result of air flowing over and under the wing
- Equation: Lift (L) = 0.5 x air density x velocity^2 x wing area x lift coefficient
Bernoulli's Principle
- Statement: The pressure of a fluid (air) decreases as its velocity increases
- Application in aerodynamics:
- Air flowing over the curved upper surface of an airfoil accelerates, reducing pressure
- Air flowing along the flat lower surface of an airfoil decelerates, increasing pressure
- Resulting pressure difference creates an upward force (lift)
Rotary Wing
- Definition: A type of wing that rotates to produce lift and thrust
- Characteristics:
- Blades angled to produce lift and thrust
- Rotating motion creates a swirling airflow around the blade
- Application:
- Helicopters: Use rotary wings to generate both lift and thrust
- Wind turbines: Use rotary wings to convert wind energy into mechanical energy
Aerodynamics
-
Airfoil: A curved surface that produces lift when air flows over it, characterized by a cambered upper surface, flat lower surface, and angled to oncoming airflow.
- Converts airflow into an upward force (lift) and a forward force (thrust)
Forces in Flight
-
Thrust: The forward force that propels an aircraft through the air, generated by engines and created by accelerating air rearward.
- Equation: Thrust (T) = mass flow rate x velocity change
-
Drag: The backward force that opposes an aircraft's motion, consisting of friction drag and induced drag.
- Factors affecting drag: air density, velocity, shape and size of the aircraft, and surface roughness
-
Lift: The upward force that opposes an aircraft's weight, generated by the shape of the airfoil and resulting from air flowing over and under the wing.
- Equation: Lift (L) = 0.5 x air density x velocity^2 x wing area x lift coefficient
Bernoulli's Principle
- Statement: The pressure of a fluid (air) decreases as its velocity increases.
-
Application in aerodynamics:
- Air flowing over the curved upper surface of an airfoil accelerates, reducing pressure.
- Air flowing along the flat lower surface of an airfoil decelerates, increasing pressure.
- Resulting pressure difference creates an upward force (lift).
Rotary Wing
- Definition: A type of wing that rotates to produce lift and thrust, characterized by blades angled to produce lift and thrust.
-
Characteristics:
- Rotating motion creates a swirling airflow around the blade.
-
Applications:
- Helicopters: Use rotary wings to generate both lift and thrust.
- Wind turbines: Use rotary wings to convert wind energy into mechanical energy.
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Description
Test your understanding of airfoils, their characteristics and function in producing lift, and how thrust is generated to propel an aircraft forward.
