![]() Describe how the shape, area and speed of an object affects drag.Explain that drag is one of the four main forces acting on airplanes.Minimizing the amount of drag acting on aircraft often involves modifying the wing and/or fuselage shapes.Īfter this lesson, students should be able to: Since drag slows down airplanes and makes them less efficient (requiring more fuel), engineers aim to design planes that reduce drag. When designing airplanes, engineers keep in mind the force of drag and the principle of energy conservation. This engineering curriculum aligns to Next Generation Science Standards ( NGSS). They explore the relationship between drag and the shape, speed and size of objects. They learn the difference between friction drag, form drag and induced drag, and how thrust is involved. The center of gravity is the average location of the weight of an object Longitudinal Stability The stability of an aircraft in the longitudinal, or pitching, plane under steady-flight conditions Lateral Stability Stability about the airplane's longitudinal axis, which extends form nose to tail, is called lateral stability Directional Stability Directional stability is stability of a moving body or vehicle about an axis which is perpendicular to its direction of motion.Students learn about the drag force on airplanes and are introduced to the concept of conservation of energy and how it relates to drag. Two broad drag classifications Parasite drag: drag created by airplane design Induced drag: by-product of lift generation Acts through the center of pressureĦ Thrust Forward-acting force opposes dragĭirection of thrust depends on design Propulsion systems produce thrust Equal to drag in straight, constant speed flightħ Stability Center of Gravity Longitudinal Stability Lateral Stability Varies with passengers, cargo, fuel load decreases as fuel is consumed or payload off-loaded Direction is constant toward earth’s center May be assumed concentrated at the center of gravityĥ Drag An aerodynamic force Drag is also called air resistance. Therefore, the air on the underside of the plane is exerting more pressure, causing the plane to lift. Generated by motion of aircraft through air Created by the effects of airflow past wing The top of an airplane wing is curved, so that air has to travel further to reach the trailing end of the wing. These torques will rotate the aircraft in the appropriate direction.ģ Lift Lift is an aerodynamic force Lift must exceed weight for flight Once in the air, airplanes maneuver by moving control surfaces which provide torques about the center of mass of the airplane. ![]() Therefore, to make the airplane work, one must have sufficiently powerful engines to push the plane through the air, and have designed wings to lift the plane in the air. Likewise, if the lifting force of the wings is greater than the weight of the plane (the force of gravity), the plane will rise in the air. If the trust of the airplane’s engines is greater than the force of the wind (drag force), the plane will go forward. The relationship between the universal law of gravitation and the effect of gravity on an object at the surface of the earth Lift and Drag Two of the four forces on an airplane General Concept: Just like in the first page of this manual, an airplane flies by balancing forces. When one object exerts a force on a second object, the second object always exerts a force of equal magnitude and opposite direction (Newton's 3rd Law). Standards in this lesson: Physics-motion and forces-Newton’s laws When forces are balanced no acceleration occurs thus an object continues to move at a constant speed or stays at rest (Newton's 1st Law). If the forces are unbalanced, the aircraft accelerates in the direction of the largest force. If the forces are balanced, the aircraft cruises at constant velocity. The motion of the airplane through the air depends on the relative strength and direction of the forces shown above. This slide shows the forces that act on an airplane in flight. Source NASA Glen Research Center Learning Technologies A force may be thought of as a push or pull in a specific direction. Presentation on theme: "Four Forces of Flight Lift Weight Thrust Drag"- Presentation transcript:ġ Four Forces of Flight Lift Weight Thrust Drag
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