How aircraft fly in the sky?

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  • 1 decade ago
    Favourite answer

    For an airplane to fly, it must always engage in a tug of war between the opposing forces of lift versus weight and thrust versus drag.

    For a moment, think of an airplane moving from right to left and the flow of air moving from left to right. The weight or force due to gravity pulls down on the plane opposing the lift created by air flowing over the wing. Thrust is generated by the propeller and opposes drag caused by air resistance to the airplane. During take off, thrust must be greater than drag and lift must be greater than weight so that the airplane can become airborne.

    For landing thrust must be less than drag, and lift must be less than weight.

    THE FOUR FORCES ACTING ON AN AIRPLANE

    An airplane in flight is the center of a continuous tug of war between four forces: lift, gravity force or weight, thrust, and drag. Lift and Drag are considered aerodynamic forces because they exist due to the movement of the aircraft through the air. The weight pulls down on the plane opposing the lift created by air flowing over the wing. Thrust is generated by the propeller and opposes drag caused by air resistance to the frontal area of the airplane. During take off, thrust must overcome drag and lift must overcome the weight before the airplane can become airborne. In level flight at constant speed, thrust exactly equals drag and lift exactly equals the weight or gravity force. For landings thrust must be reduced below the level of drag and lift below the level of the gravity force or weight.

    Lift

    Lift is produced by a lower pressure created on the upper surface of an airplane's wing compared to the pressure on the wing's lower surface, causing the wing to be "lifted" upward. The special shape of the airplane wing (airfoil) is designed so that air flowing over it will have to travel a greater distance faster, resulting in a lower pressure area (see illustration) thus lifting the wing upward. Lift is that force which opposes the force of gravity (or weight).

    Thrust

    Thrust is a force created by a power source which gives an airplane forward motion. It can either "pull" or "push" an airplane forward. Thrust is that force which overcomes drag. Conventional airplanes utilize engines as well as propellers to obtain thrust.

    Drag

    Drag is the force which delays or slows the forward movement of an airplane through the air when the airflow direction is opposite to the direction of motion of the airplane. It is the friction of the air as it meets and passes over and about an airplane and its components. The more surface area exposed to rushing air, the greater the drag. An airplane's streamlined shape helps it pass through the air more easily.

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  • 1 decade ago

    Aircraft have wings which generate lift when air flows over their surfaces. (Bernoullis Theorem).

    Engines (props or jet turbines) propel the aircraft in the air to create the airflow required for generating the lift and holding them in the air. Control surfaces like the aileron and elevators control the rolling (side to side movement) and pitching (up and down movement) respectively. The rudder controls the yawing which is the movement of the aircraft along its vertical axis.

    To climb the power is increased and to descend, vice versa, is is reduced.

    There are four forces which act on an aircraft. These are lift, drag, weight and thrust. All must be aptly applied and controlled in order to make the aircraft fly.

    Source(s): none
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  • 1 decade ago

    Lets assume that the airplane is moving forward from some type of propulsion system. The way a airplane flies is due to the difference between air pressure on the wings. If you notice, the top of a wing is curved and the bottom is flat. When air flows towards a wing, half flows over the top and the other half under the wing. The interesting fact about splitting air is that they like to reattach at the end of the wing. Since the top of the wing is curved, the air has to travel a greater distance. If the air on the top of the wing wants to reattach to the air at the bottom of the wing, it has to go faster. Since the air molecules flows faster on the top of the wing, a low pressure is created. A high pressure is created at the bottom of the wing. Low pressure = vacuum on top of wing that sucks the wing upward. High pressure = upward push on bottom on wing. The two forces combine creates total lift. The faster an airplane forward movement is, the greater these forces are. Now see why airplanes have to go a certain speed in order to become airborne. The total force created by the pressure difference has to be greater than the weight of the plane.

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  • Anonymous
    1 decade ago

    The Aircrafts fly with the principle of Lift (i.e, allowing air to pass below the vehicle while moving at high speeds say 200kmph). The engine used in a typical aircraft is a turbojet engine which propel the aircraft to attain high velocity and as the speed increases the air below the aircraft lift the craft and as it reach higher and higher the air pressure becomes more delicate and makes a plane an easy flier....

    For more details on it http://www.allstar.fiu.edu/aero/fltmidfly.htm

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  • sristi
    Lv 5
    1 decade ago

    when the silly birds can fly, why not an aircraft?

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  • Anonymous
    1 decade ago

    Easier than flying in dirt or into buildings.

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  • 1 decade ago

    Not sure if your looking for the short answer or long. Just type your question in any search engine and you will find 1,000's of pages that answer your question.

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  • 1 decade ago

    May be u can start flying too ,, why dont u also try

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  • 1 decade ago

    Jesus christ, you people are confusing the kid...

    The correct answer is: God did it.

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  • andy t
    Lv 6
    1 decade ago
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