The history of Aerodynamic laws – Journey from a bathtub, an apple tree to modern planes everything you need to know!

Tracing back the history of Aerodynamics

The branch of dynamics that is reliant on the study of the motion of air is called aerodynamics. Right-back in the 2nd and 3rd centuries BC, Aristotle and Archimedes(the bathtub guy obviously), had their hands work on the fundamental concepts of aerodynamics. The quantitative theory only began when Isaac Newton( the apple guy), in 1726 became the first aerodynamicist.

The man who discovered gravity also developed a theory of air resistance. Probably he wondered how come the apple takes more time to hit the ground than an apple with a slightly different shape. The theory however was later verified for low flow speeds. To add development theories to this various people worked to provide theories and applications, leading to the modern ways of aerodynamics seen today.

Evolution of life in the aerodynamics

If you’re wondering who came up with these four aerodynamic forces of the flight? The answer for that would be Sir Credit Cayley. He put forth the basic forces that act upon a flight. They are namely weight(the weight of the aircraft), thrust(the forward force that propels the aircraft), drag, and lift. You can learn more about these forces in my previous article here. The force that is required to push the solid body against the force of air is determined by its weight.

Any aircraft that follows the traditional airfoil design, in the air tend to experience an upward lift force. The lift force acts along with the thrust produced by the engine. The force of its weight and a drag force acts along(read: Lift in aerodynamics). The density which is also known as mass, when increased the inertia increases producing more resistance resulting in drag( read: Drag in aerodynamics)

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The laws governing aerodynamics 

The fluid dynamic conservation laws, basically the definitions that explain aerodynamics are 4. The four of them are the law of conservation of mass, momentum, and energy. The law of conservation of mass puts forth the theory that any mass can never be created, it can either be created or destroyed. When a system is in a closed condition, where matter cannot be exchanged and external forces cannot react, the total momentum is found to be constant.

While the law of conservation of energy states that in an isolated system, the sum of the energy remains to be constant. These laws are found to govern the principles of aerodynamics. Navier-stokes equation, Euler’s equation, and Bernoulli’s equation are having their base on these laws.

The aerodynamic tree family

Based on the properties of flow aerodynamics is classified into:

1. Compressible Aerodynamics 

If the density varies along a streamlined body according to the aerodynamic theory, then the flow is said to be compressible where the variations in density are taken into account.

2. Incompressible Aerodynamics

The density of an incompressible flow is said to be constant in both time and space. When the rate of flow is smaller than the speed of sound, it is a case of incompressible flow. 

Based on the properties of flow speed aerodynamics is classified into:

1. Subsonic flow
The study of fluid motion with a speed much slower than the speed of sound in the flow is called subsonic flow. 
2. Transonic flow
The flow that ranges over velocities just below and above the Mach 0.8–1.2 local speed of sound is called transonic flow.
3. Supersonic flow
If the speed of the flow is much higher than the speed of sound then the flow is called supersonic flow.
4. Hypersonic flow
Extremely high supersonic speeds in aerodynamics are called hypersonic flow.

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