“the Evolution of Airplanes”

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“The Evolution of Airplanes”
Introduction
This year is the 200th birthday of Charles Darwin (1809-1882), the father of evolution. Darwin’s evolution theory proposes that all species of organisms, including human beings, evolved from common ancestors. There are five main characteristics in his evolution theory. First, there are variations among each population. Second, organisms compete for limited resources to exist. Third, traits of offspring are inherited from their parents. Forth, organisms reproduce to keep themselves from extinction. Lastly, organisms with better traits are more likely to survive and reproduce[i].

All living organisms follow the evolution theory. Surprisingly, some non-living objects also show characteristics of evolution. Airplanes, for instance, exhibit variations among different models; models with better function can be produce in mass amount while others are eliminated from the market.

This essay focuses on how airplanes were modified throughout these years and how they demonstrate the evolution theory of Darwin.

The evolution process of airplanes
Before the invention of airplane, people use lighter-than-air flying machine for aviation, air balloon and airship for example. These machines cannot undergo a prolong flight and they have limitation in speed, height and capacity. Unlike airship and air balloon, airplane overcomes the border between countries and has great impact in human transportation history.

Pioneer
The first person having the idea to build a flying machine was not The Wright Brothers; it was Leonardo da Vinci, the great scientist. Leonardo studied the flight of birds and their structure, then in about 1490, he designed a wing-flapping device known as ornithopter, which was designed to be human-powered[ii]. Although the machine was not built, his idea had inspired others to make one.

Breakthrough in heavier-than-air flight
In the past, scientists believed that birds can fly forward and lift because of the propulsion force generated by the wings, so they built ornithopter, a flying machine with wings like structure. In late 17th century, a scientist named George Cayley had different idea towards the flying principle of birds. He believed that the wings of birds are in a specialized structure to produce lifting force for the bird. Using his own idea, he designed a few flying machines. One of his designs has structure similar to that of modern airplane, with airfoils, a fuselage, a tail with cruciform structure for control of vertical and horizontal movement, and a steering for pilot. Revolving vanes are used as the propulsion force. A hundred of year later, revolving vanes are transformed into propellers. In 1804, he made a glider, which is a kite like flying devices, and it flew. After that, Cayley modified his flying machine by increasing the area and rigidity of wings, and modified the streamline shape. Although the machine can fly, it could not fly for a long time due to a lack of a light weight power source[iii].

First practical airplane
In 1890s, people began to gain interest in aviation. During 1899 to 1905, Orville Wright and Wilbur Wright, known as the Wright Brothers, carried out a series of experiment about aeronautic. They made the Wright Kite in 1899, which is an uncontrolled large glider, followed by a scale model of glider in 1900. Although the glider can fly, the lift produced by the plane was less than their expectation. Later, they introduced canard into the glider, which is a horizontal rudder at the front of the glider. They ignored others’ previous published data about the structure of airfoils, and established a new idea of how centre of pressure moves about an airfoil. They carried out experiments using two hundreds of different airfoils; they installed an elevator wing and double fin fixed at the rear. After hundreds of modifications and calculations, the Wright Brothers finally made a practical powered airplane with a propeller and...
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