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Four Forces
                    Sati Anasuya explained, “Oh dear Bharadwaja! An object in flight is constantly engaging in a tug of war between the opposing forces of lift, weight (gravity), thrust and drag. Flight depends on these forces – whether the lift force is greater than the weight force and whether thrust is greater than drag (friction) forces. Lift and drag are considered aerodynamic forces because they exist due to the movement of an object (such as a plane) 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 (engine) and opposes drag caused by air resistance. During take-off, thrust must counteract drag and lift must counteract the weight before the plane can become airborne.

If a plane or bird flies straight at a constant speed:  Lift force upwards = weight force downwards (so the plane/bird stays at a constant height)  Thrust force forwards = opposing the force of drag (so the plane/bird stays at a constant speed).

If the forces are not equal or balanced, the object will speed up, slow down or change direction towards the greatest force."...Read  Vedic Vaimānika and know more about  Ancient Marvel Aircraft Science...          Sivkishen Ji., Author

