Aircraft - Early Theories Of Air Travel, Lighter-than-air Aircraft, Heavier-than-air Aircraft
type machines
An aircraft is a machine used for traveling through the atmosphere supported either by its own buoyancy or by some sort of engine that propels the ship through the air. Aircraft of the former type are known as lighter-thanair ships, while those of the latter type tend to be heavier-than-air machines. Included in the general term aircraft are specific machines such as dirigibles, gliders, airplanes, and helicopters.
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The first real success experienced by humans in designing aircraft made use of the concept of buoyancy. Buoyancy refers to the fact that an object tends to rise if it is placed in a medium whose density is greater than its own. A cork floats in water, for example, because the cork is less dense than the water. Buoyant aircraft became possible when scientists discovered that certain gases—es…
Cayley's glider is now regarded as the earliest version of the modern airplane. The glider—also known as a sailplane—differs from a modern airplane only in that it has no power source of its own. Instead, it uses updrafts and winds for propulsion and maneuvering. Cayley was well aware of the need for a powerful engine for moving a heavier-than-air machine, but only steam engin…
The age of modern aviation can be said to have begun on December 17, 1903 at Kitty Hawk, North Carolina. On that date, Wilbur and Orville Wright, two bicycle makers from Dayton, Ohio, flew the world's first powered aircraft, a biplane (double-winged aircraft) with a wing span of 40 ft 4 in (12 m 1.5 cm) and weighing 605 lb (275 kg). The plane remained in the air a total of only 12 seconds a…
An airplane does not fly, of course, simply by setting it out on the runway and waiting for a strong wind to blow over its wings. Instead, the airplane is caused to move forward, forcing it to rush through still air at a high rate of speed. The forward thrust for the aircraft comes from one of two sources: a rotating propeller blade powered by some kind of engine or a rocket engine. The propeller …
Once it is in flight, an airplane is subject to three major types of movements: pitch, yaw, and roll. These three terms describe the possible motion of an airplane in each of three dimensions. Pitch, for example, refers to the tendency of an airplane to rotate in a forward or backward direction, tail-over-nose, or vice versa. Yaw is used to describe a horizontal motion, in which the airplane tends…
Until the 1940s, the only system available for powering aircraft was the piston-driven propeller engine. In order to increase the speed and lifting power of an airplane, the only option that aeronautical engineers had was to try to increase the efficiency of the engine or to add more engines to the airplane. During World War II, the largest power plants consisted of as many as 28 cylinders, capabl…
No matter what kind of power system is being used in an aircraft, aeronautical engineers are constantly searching for new designs that will improve the aerodynamic properties of aircraft. Perhaps the single most valuable tool in that search is the wind tunnel. A wind tunnel is a closed space in which the model of a new airplane design is placed. A powerful fan at one end of the tunnel is then turn…
Many people may think of the modern aircraft business as being dominated by military jet fighters and bombers, commercial jetliners and prop planes, and other similar large aircraft. But flying has become a popular hobby among many people in the world today, and, as a result, a number of special kinds of aircraft have been developed for use by ordinary people. One example is the bicycle drive ligh…
A helicopter is an aircraft that has the capability of maneuvering in both horizontal and vertical directions. It accomplishes these maneuvers by means of a single elaborate and rather remarkable propeller-like device mounted to its top. Although the device looks like an ordinary propeller, it is much more complicated. In fact, the device is more properly thought of as a pair of wings (rotor blade…
Guiding the motion of aircraft through the skies is a serious problem for two reasons. First, commercial and military aircraft now fly in all kinds of weather, often under conditions that prevent them from seeing other aircraft, the ground, or the airports at which they are supposed to land. Second, there is so much traffic in the air at any one time in many parts of the world that precautions mus…
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