Airplane aerodynamics consider the interactions between air and a flight machine that are responsible for creating and sustaining flight. Factors such as pressure, velocity, and weight are important in understanding aerodynamic principles generally and airplane aerodynamics in particular. The lift conditions created by the interaction of a plane's wing and surrounding air are vital. Drag and thrust — or resistance and forward motion — entail the other main concepts of airplane aerodynamics.
Aerodynamics in general concerns how certain forces affect the way objects move through the air. As such, aerodynamics can affect anything from a toy like a kite or a ball to a major transportation machine like an airplane. An object in motion will affect the gaseous air that comprises earth's atmosphere. This air, in turn, will affect the object.
Understanding the composition of air can shed more light on airplane aerodynamics. Air is considered a physical body because it has weight and mass. Unlike solid bodies, however, molecules found in air are loosely connected. A body of air may therefore easily change shape and direction when pressure is placed upon it. As altitude increases, the pressure exerted upon the air by gravitational forces lowers, leading to a loss in weight the higher the air rises. Both increases in moisture and increases in temperature can also affect weight or density.
Air's weight creates pressure against objects moving through it. This pressure is measured and acts upon various airplane instruments, including the pressure gauge and the airspeed indicator. Changes in pressure can lessen a plane's power due to a lack of air in the engine, reduce the efficiency of a propeller, and impact the basis of airplane aerodynamics: lift.
One factor that can influence the amount of pressure is speed. According to a popular explanation known as Bernoulli’s Principle, accelerating speed would have a converse effect on pressure. Such is the effect an airplane wing has on air pressure when it is in movement. The low pressure creates a Magnus Effect, which consists of an upward moving force, or lift.
The design of the wing — or airfoil — helps create the pressure conditions necessary to create a lift. In most airplanes, the top part of the wing is more curved, as is the front end. This leads to a difference in surface velocity because molecules must move farther and faster in the curved areas, facilitating a consequent lower pressure on the wing’s top. The air below the wing can then sustain an upward movement.
Some scholars, however, believe that Bernoulli's Principle fails to explain flight capabilities for airplanes or other machines with nontraditional wing structures. Rather, basic airplane aerodynamics can be explained with simple applications of the physics theories of Isaac Newton. Generally put, the airplane's power source, or engine, causes the wing to push against air with a high velocity, or speed. This forces massive amounts of air below the wing. The air's downward motion action thus creates a lifting action around the wing.
Airplanes create a thrust that allows them to move forward via propellers and jet engines. The former power source operates like a giant fan that pushes against air for thrust. Jet engines use fuel and other energy sources in creating and sustaining thrust. In order to fly, aircraft must overcome the natural resistance they face when moving through air, also known as drag.