Beginning of Essay
One of the first things that is likely to be noticed during a visit to the local airport is thewide variety of airplane styles and designs. No matter what each looks like like they alldepend on the the same four factors which are lift, weight, thrust, and drag L ....

Middle of Essay
.... in equilibrium, but the aerodynamic forces are not a factor. In calm wind conditions, the atmosphere exerts equal pressure on the upper and lower surfaces of the wing. Movement of air about the airplane, particularly the wing, is necessary before the aerodynamic force of lift becomes effective. During flight, however, pressures on the upper and lower surfaces of the wing are not the same. Although several factors contribute to this difference, the shape of the wing is the principal one. The wing is designed to divide the airflow into areas of high pressure below the wing and areas of comparatively lower pressure above the wing. This pressure diffe ....