supersonic transport


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airplane

airplane, aeroplane, or aircraft, heavier-than-air vehicle, mechanically driven and fitted with fixed wings that support it in flight through the dynamic action of the air.

Parts of an Airplane

The airplane has six main parts—fuselage, wings, stabilizer (or tail plane), rudder, one or more engines, and landing gear. The fuselage is the main body of the machine, customarily streamlined in form. It usually contains control equipment, and space for passengers and cargo. The wings are the main supporting surfaces. Modern airplanes are monoplanes (airplanes with one wing) and may be high-wing, mid-wing, or low-wing (relative to the bottom of the fuselage). At the trailing edge of the wings are auxiliary hinged surfaces known as ailerons that are used to gain lateral control and to turn the airplane.

The lift of an airplane, or the force that supports it in flight, is basically the result of the direct action of the air against the surfaces of the wings, which causes air to be accelerated downward. The lift varies with the speed, there being a minimum speed at which flight can be maintained. This is known as the stall speed. Because speed is so important to maintain lift, objects such as fuel tanks and engines, that are carried outside the fuselage are enclosed in structures called nacelles, or pods, to reduce air drag (the retarding force of the air as the airplane moves through it).

Directional stability is provided by the tail fin, a fixed vertical airfoil at the rear of the plane. The stabilizer, or tail plane, is a fixed horizontal airfoil at the rear of the airplane used to suppress undesired pitching motions. To the rear of the stabilizer are usually hinged the elevators, movable auxiliary surfaces that are used to produce controlled pitching. The rudder, generally at the rear of the tail fin, is a movable auxiliary airfoil that gives the craft a yawing (turning about a vertical axis) movement in normal flight. The rear array of airfoils is called the empennage, or tail assembly. Some aircraft have additional flaps near the ailerons that can be lowered during takeoff and landing to augment lift at the cost of increased drag. On some airplanes hinged controls are replaced or assisted by spoilers, which are ridges that can be made to project from airfoils.

Airplane engines may be classified as driven by propeller, jet, turbojet, or rocket. Most engines originally were of the internal-combustion, piston-operated type, which may be air- or liquid-cooled. During and after World War II, duct-type and gas-turbine engines became increasingly important, and since then jet propulsion has become the main form of power in most commercial and military aircraft. The landing gear is the understructure that supports the weight of the craft when on the ground or on the water and that reduces the shock on landing. There are five common types—the wheel, float, boat, skid, and ski types.

Developments in Airplane Design

Early attempts were made to build flying machines according to the principle of bird flight, but these failed; it was not until the beginning of the 20th cent. that flight in heavier-than-air craft was achieved. On Dec. 17, 1903, the Wright brothers produced the first manned, power-driven, heavier-than-air flying machine near Kitty Hawk, N.C. The first flight lasted 12 sec, but later flights on the same day were a little longer; a safe landing was made after each attempt. The machine was a biplane (an airplane with two main supporting surfaces, or wings) with two propellers chain-driven by a gasoline motor.

The evolution of the airplane engine has had a major effect upon aircraft design, which is closely associated with the ratio between power load (horsepower) and weight. The Wright brothers' first engine weighed about 12 lb (5.4 kg) per horsepower. The modern piston engine weighs about 1 lb (0.4 kg) or less per horsepower, and jet and gas-turbine engines are much lighter. With the use of jet engines and the resulting higher speeds, airplanes have become less dependent on large values of lift from the wings. Consequently, wings have been shortened and swept back so as to produce less drag, especially at supersonic speeds. In some cases these radically backswept wings have evolved into a single triangular lifting surface, known as a delta wing, that is bisected by the fuselage of the plane. Similar alterations have been made in the vertical and horizontal surfaces of the tail, again with the aim of decreasing drag.

For certain applications, e.g., short-haul traffic between small airports, it is desirable to have airplanes capable of operating from a runway of minimum length. Two approaches to the problem have been tried. One, the vertical takeoff and landing (VTOL) approach, seeks to produce craft that take off and land like helicopters, but that can fly much faster. The other approach, short takeoff and landing (STOL), seeks to design more conventional aircraft that have reduced runway requirements. The lessened lift associated with swept-back wing designs increases the length of runway needed for takeoffs and landings. To keep runway lengths within reasonable limits the variable-sweep, or swing, wing has been developed. A plane of this type can extend its wings for maximum lift in taking off and landing, and swing them back for travel at high speeds.

A proposed variant of the swing wing, in which one wing sweeps to the rear and another forward, produces an arrangement that causes a minimum shock wave at supersonic speeds. It is thought that if this modification were applied to supersonic transport (SST) designs it would somewhat lessen their objectionable noise levels. No solution has been proposed to lessen their high fuel consumption, however. Recent developments in fan-jet engines, in which a turbine powers a set of vanes that drive air rearward to augment thrust, have made supersonic flight possible at low altitude. Much research has also gone into reducing the noise and air pollution caused by jet engines.

See aerodynamics; airport; aviation; autogiro; glider; seaplane.

Bibliography

See bibliography under aviation.

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supersonic transport

[¦sü·pər¦sän·ik ′tranz‚pȯrt]
(aerospace engineering)
A transport plane capable of flying at speeds higher than the speed of sound. Abbreviated SST.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
The team's speciality is a measurement technique that can resolve the rapidly evolving turbulent flow eddies that contribute most intensely to supersonic jet noise of the type generally found in military-style engines, and predicted for use in future commercial supersonic transport aircraft.
OThe patent addresses only one of the three major issues with supersonic transport aircraft, the first one being noise on takeoff,O Mark Drela, a professor at the Dept.
An important step was what NASA researcher Walter Vincenti has called, "the notion that specifications could usefully be written for something as subjectively perceived as flying qualities." In a brief review, it is not feasible to trace the many steps to hypersonic flight which this volume does so clearly: breaking the sound barrier (a most significant psychological breakthrough), variable sweep wings, the ill-fated supersonic transport (SST), and the shift from aeronautics to space research.
The National Aerospace Laboratory of Japan said Friday it will test a small experimental airplane next month in southern Australia as part of its efforts to develop next-generation supersonic transport.
His findings, the committee said, sparked research on "global biogeochemical cycles" as well as the effects on the stratosphere of nitrogen oxide--spewing supersonic transport planes.
The future of the civilian aircraft industry may lie with development of the High-Speed Civil Transport (HSCT), an environmentally benign successor to the Concorde supersonic transport. The United States dropped out of the race to build a supersonic transport in the 1970s when it became clear that the existing technology would result in a plane that was very expensive to operate, emitted significant quantities of nitrogen oxide, and produced unacceptable levels of noise when operated over land.
NTU scored its first victory when it helped scuttle the Nixon administration's proposal to build a supersonic transport like the Concorde.
The supersonic transport aircraft had been in development for several years, with the first prototype flying in 1968.
For example, the Udvar-Hazy Center shelters, among others, the Space Shuttle Enterprise, the Lockheed SR--71 Blackbird, (see photo page 57) the BAC/Aerospatiale supersonic transport Concorde, the famed Boeing B-29 Enola Gay, an IMAX theater, a 164-foot observation tower, and much, much more.
The Industrial Science and Technology Agency under the Ministry of International Trade and Industry will initiate the engine project for the supersonic transport (SST) plane, they said.
Fahey, an atmospheric scientist at the National Oceanic and Atmospheric Administration in Boulder, Colo., and his colleagues have measured exhaust emissions from a Concorde supersonic transport (SST) plane during high-altitude flight.