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Drag and Other Factors |
Drag Force
Drag force (often shortened to drag) is a a resistive force that acts against motion. Drag is very similar to the force of friction, however rather than two surfaces being in contact, drag
occurs between fluids (including gases) and an object. Drag can be modeled with a fairly simple equation assuming that: the air the object is passing through is near the Earth's surface,
the size of the object ranges from a few millimeters to a few meters, and the object possesses a speed that is less than several hundred meters/second.
Drag is modeled by: Drag = (1/2)*C*p*A*v^2 Where: C = drag coefficient, p = the density of the air, A = the cross sectional area, v = velocity
After examining the equation, it is evident that increased velocity greatly increases the amount of drag force generated as the "v" term is squared.
Lift
Image Source: Image Source:
http://www.daviddarling.info/childrens_encyclopedia/flight_Chapter2.html http://www.grc.nasa.gov/WWW/k-12/VirtualAero/BottleRocket/airplane/inclind.html
Lift is the upward force responsible for the aircraft's ability to remain in the air, and counters the downward force of gravity. Lift is generated by the flow of air around an airfoil,
where zones of low and high pressures are generated above and below the airfoil, respectively. This created pressure differential causes the airfoil to experience an upwards force.
These areas of pressure are created by a difference in the velocities of the respective air streams flowing over the airfoil. As such, in order to generate a required magnitude of lift, a
certain velocity must be maintained or exceeded for the required pressure differential to be generated. This minimum velocity is the cause of a phenomena known as stalling. During a
stall the aircraft's speed is insufficient to generate the lift required to keep it airborne and it begins to fall. This phenomena may also be experienced when the angle of the aircraft's airfoil is too great in comparison to its direction of travel and sufficient turbulent flow is generated as the speed of the air-flows over the airfoil decrease.
Drag force (often shortened to drag) is a a resistive force that acts against motion. Drag is very similar to the force of friction, however rather than two surfaces being in contact, drag
occurs between fluids (including gases) and an object. Drag can be modeled with a fairly simple equation assuming that: the air the object is passing through is near the Earth's surface,
the size of the object ranges from a few millimeters to a few meters, and the object possesses a speed that is less than several hundred meters/second.
Drag is modeled by: Drag = (1/2)*C*p*A*v^2 Where: C = drag coefficient, p = the density of the air, A = the cross sectional area, v = velocity
After examining the equation, it is evident that increased velocity greatly increases the amount of drag force generated as the "v" term is squared.
Lift
Image Source: Image Source:
http://www.daviddarling.info/childrens_encyclopedia/flight_Chapter2.html http://www.grc.nasa.gov/WWW/k-12/VirtualAero/BottleRocket/airplane/inclind.html
Lift is the upward force responsible for the aircraft's ability to remain in the air, and counters the downward force of gravity. Lift is generated by the flow of air around an airfoil,
where zones of low and high pressures are generated above and below the airfoil, respectively. This created pressure differential causes the airfoil to experience an upwards force.
These areas of pressure are created by a difference in the velocities of the respective air streams flowing over the airfoil. As such, in order to generate a required magnitude of lift, a
certain velocity must be maintained or exceeded for the required pressure differential to be generated. This minimum velocity is the cause of a phenomena known as stalling. During a
stall the aircraft's speed is insufficient to generate the lift required to keep it airborne and it begins to fall. This phenomena may also be experienced when the angle of the aircraft's airfoil is too great in comparison to its direction of travel and sufficient turbulent flow is generated as the speed of the air-flows over the airfoil decrease.
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Scramjet
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Bibliography |
Background Image By:
Lynn Chambers
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