2015 Dec

Science of Aerodynamics

December 29, 2015

Science of Aerodynamics

Aerodynamics is a branch of fluid mechanics that describes the study of the interaction of gases with objects at motion. However, the movement of air around bodies is currently the primary focus of aerodynamics – since we move, and breathe, in air. Without the science of aerodynamics, many luxuries that we use today would not exist – this includes aeroplanes, which are engineered, using aerodynamically-related concepts, for the aeronautical industry.

Although aeronautics is a relatively new field, aerodynamics (as a science) has been around for millennia. Aerodynamic concepts have been used for the earliest sailboats, and attempted flight, before ships and modern aircraft existed. It wasn’t until 1726 that Isaac Newton developed the first theory for air resistance and motion. Consequently, many scientists began developing theories concerning the science of aerodynamics. Most notably, George Cayley was first in identifying the fundamental forces related flight, namely: thrust (from an energy source), drag (resistive force), lift (due to pressure difference) and weight (gravitational force). Later, towards the beginning of the nineteenth century, the Wright brothers applied these forces to their aircraft designs to fly the first ever powered airplane. In the contemporary aeronautic, and aerospace, industries, we have already begun “space tourism” due to the rapid development occurring in the discipline of aerodynamics.

Drag and lift are two fundamental forces of flight, and proper designs considering these two forces, are therefore needed before building any aircraft. Drag is the force that is acting in the opposite direction of a body’s motion, thus it also known as air resistance, or a form of friction. Drag is generally considered an unfavourable condition, since additional energy is required to overcome this opposing force. There are, however, a few exceptions where drag is needed, such as for parachuting. There are various types of drag, namely: form, skin, interference, and wave drag. These different types of drag occur for different circumstances and environments. However, drag is calculated by one equation. Determining the amount of drag acting on an object, we can consider the drag coefficient, found in the drag equation. The value of the drag coefficient is dependent on the shape of the object, density of the air, and whether air flow is smooth or turbulent.

Lift is the force that acts at right angles to the direction of flow from a moving body – it is therefore generated by an object exerting a force on the air that flows around the body. An example we often mentioned during our Physics tuition classes for the topic of Circular motion, is the wing of an airplane that is designed to have a streamlined shape, allowing for more lift. This lift is due to the downward force of the wing on the flow of air, and also the opposite upward force, since the air exerts an equally opposing force.

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