Beginning of Essay
Flight is one of the most important achievements of mankind. We owe this achievement to the invention of the airfoil and understanding the physics that allow it to lift enormous weights into the sky. All flight is the result of forces acting upon the wings of an ....

Middle of Essay
.... of the airfoil and the angle of attack. P stands for the air mass density, V for the velocity of the air passing over the wing, and S for the area of the wing when viewed from above or below. As the air flows over the wing producing lift, it grabs onto the wings surface and causes drag. Drag can be measured by the equation D=Cd 1/2 (pV2)S, much like the lift equation. The drag coeficent Cd is found, again, by determining the shape of the airfoil and then finding the angle of attack. Drag is less than lift up to a certain angle of attack. After that, the air encountering the surface of the wing is either pushed off or deflected in a way to cau ....