Aerodynamics is the study of how gases interact with moving bodies. Because the gas that we encounter most is air, aerodynamics is primarily concerned with the forces of drag and lift, which are caused by air passing over and around solid bodies. Engineers apply the principles of aerodynamics to the designs of many different things, including buildings, bridges and even footalls however, of primary concern is the aerodynamics of aircraft and automobiles.
Aerodynamics comes into play in the study of flight and the science of building and operating an aircraft, which is called aeronautics. Aeronautical engineers use the fundamentals of aerodynamics to design aircraft that fly through the Earth’s atmosphere.
Aerodynamics of aircraft
In order to overcome drag forces, an aircraft must generate thrust. This is accomplished with a motor-driven propeller or a jet engine. When the airplane is in level flight at a constant speed, the force of the thrust is just enough to counteract the aerodynamic drag.
Moving air can also generate forces in a different direction from the flow. The force that keeps an airplane from falling is called lift. Lift is generated by an aircraft wing. The path over a wing’s curved top is longer than the path along the flat bottom of the wing. This causes the air to move faster over the top than it does along the bottom. With all other factors being equal, faster moving air has lower pressure than slower moving air, according to Bernoulli’s principle, stated by Daniel Bernoulli, one of the most important pioneers in the field of fluid dynamics. This difference is what allows the slower moving air to push up against the bottom of the wing with greater force than the faster moving air is pushing down against the top of the wing. In level flight, this upward force is just enough to counteract the downward force caused by gravity.