flight


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flight

flight, sustained, self-powered motion through the air, as accomplished by an animal, aircraft, or rocket.

Animal Flight

Adaptation for flight is highly developed in birds and insects. The bat is the only mammal that accomplishes true flight. Flying squirrels glide rather than fly, as do flying fish and flying lizards. The extinct flying reptiles known as pterosaurs are believed to have been the largest known animals capable of true flight.

Birds fly by means of the predominantly up-and-down motion of their wings. The flapping motion is not, however, straight up and down but semicircular, the wings generally moving backward on the upstroke and forward on the downstroke. That motion pushes air downward and to the rear, creating a lift and forward thrust. The leading edge of the slightly concave wings is rather sharp, and the feathers are small and close-fitting, so that a streamlined surface meets the air. On the trailing edge of each wing the interlocking of the larger feathers forms a surface that acts somewhat like the ailerons, or movable airfoils, of an airplane. In wing motion, the leading edge is twisted so as to be lower than the trailing edge in the downward stroke and above the trailing edge in the upward stroke.

Besides flapping, some birds also use gliding and soaring techniques in flight. In gliding, a bird holds its outstretched wings relatively still and relies on its momentum to keep it aloft for short distances. In soaring, a bird uses rising warm air currents to give it lift.

The form and size of wings vary in different birds. In woodland birds the wings are somewhat rounded and have a relatively broad surface area. Birds with well-developed gliding ability, such as gannets and gulls, usually have narrow, pointed wings. Especially noted for their soaring power are eagles, vultures, crows, and some hawks. In soaring flight the feathers on the wings of these birds separate at the tips, resembling opened fingers against the sky. It is thought that this movement diverts the airstream over the wing and aids the bird in turning, banking, and wheeling. There is disagreement as to the maximum speeds achieved by birds in flight. While the flight speeds of most birds range from 10 to 60 mi (16–100 km) per hr, some have been recorded at speeds reaching 70 mi (110 km) per hr, for long distances and near 100 mi (160 km) per hr, for short flights. In a stoop, falcons can reach faster speeds.

Aircraft and Rocket Flight

Humanity's first attempts at flight were made with flapping wings strapped to the arms in imitation of birds, but these had no success. Machines designed to fly in this way, called ornithopters, date to antiquity (c.400 B.C.) and models that are capable of flight have been known for more than 100 years. However, there are no practical aircraft based on ornithopter designs, even though an ornithopter—which has no theoretical top speed limit—should be capable at least of efficient low-speed flight. In the 1930s an Italian model weighing approximately 50 lb (110 kg) and powered by a 0.5-hp motor was successfully flown.

Airships and balloons owe their ability to ascend and remain aloft to their inflation with a gas lighter than air; this is an application of Archimedes' principle of flotation, i.e., that a body immersed in a fluid (liquid or gas) is buoyed up by a force equal to the weight of the fluid that it displaces. Aircraft, which are heavier than air, are able to remain aloft because of forces developed by the movement of the craft through the air. Propulsion of most aircraft derives from the rearward acceleration of the air. It is an application of Newton's third law, i.e., that for every action there is an equal and opposite reaction. In propeller aircraft the forward motion is obtained through conversion of engine power to thrust by means of acceleration of air to the rear by the propeller. Lift is obtained largely from the upward pressure of the air against the airfoils (e.g., wings, tail fins, and ailerons), on whose upper surface the pressure becomes lower than that of the atmosphere. In jet-propelled aircraft, propulsion is achieved by heating air that passes through the engine and accelerating the resultant hot exhaust gases rearward at high velocities. Rockets are propelled by the rapid expulsion of gas through vents at the rear of the craft. The high speeds that are produced by jet and rocket engines have brought about substantial changes in the science of flight.

See aerodynamics; airplane; jet propulsion; rocket.

Bibliography

See H. Tennekes, The Simple Science of Flight (1996, repr. 2009); see also bibliography under aviation.

The Columbia Electronic Encyclopedia™ Copyright © 2022, Columbia University Press. Licensed from Columbia University Press. All rights reserved.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Flight

 

a tactical and fire subunit composed of three or four aircraft, of different arms of aviation. Several flights make up a squadron. A flight may carry out its combat mission as part of the squadron or independently.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

flight

[flīt]
(aerospace engineering)
The movement of an object through the atmosphere or through space, sustained by aerodynamic reaction or other forces.
(civil engineering)
A series of stairs between landings or floors.
(mechanical engineering)
Plain or shaped plates that are attached to the propelling mechanism of a flight conveyor.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

flight

A continuous series of steps with no intermediate landings.
McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.

flight

i. A single aircraft airborne on a nonoperational mission.
ii. The basic tactical unit in the air force, consisting of four or more aircraft in two or more elements.
iii. One of the elements of the squadron (e.g., A flight, B flight, etc.).
iv. The art or the act of flying with wings or in an airplane or other vehicle.
v. The movement of an object through the atmosphere or space sustained by aerodynamic, aerostatic, or reaction forces or by orbital speed. The movement of a human-operated or humancontrolled device, such as a rocket, a space probe, a space vehicle, or an aircraft. Also, an instance of such a movement.
vi. A regular air journey, numbered and at a fixed time, made by an aircraft.
An Illustrated Dictionary of Aviation Copyright © 2005 by The McGraw-Hill Companies, Inc. All rights reserved

flight

1. 
a. a scheduled airline journey
b. an aircraft flying on such a journey
2. the basic tactical unit of a military air force
3. a journey through space, esp of a spacecraft
4. Athletics
a. a single line of hurdles across a track in a race
b. a series of such hurdles
5. a bird's wing or tail feather; flight feather
6. a feather or plastic attachment fitted to an arrow or dart to give it stability in flight
7. See flight arrow
8. the distance covered by a flight arrow
9. Sport, esp cricket
a. a flighted movement imparted to a ball, dart, etc.
b. the ability to flight a ball
10. Angling a device on a spinning lure that revolves rapidly
11. a large enclosed area attached to an aviary or pigeon loft where the birds may fly but not escape
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
References in periodicals archive ?
Well, here's another saying, one I recommend Brownshoes actually take to heart: "Brief the flight; fly the brief." 'Nuff said.
Due to winds, flight times can differ substantially, depending on the direction of travel.
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Northwest Airlines Flight 17 bound for Narita from New York will arrive at 3 p.m.
Greg Witter in communications frantically called flight operations but no one answered.
So far, the strategy has worked well--so well that each flight has been profitable from day one, according to Garcia.
Courier flights offer relatively little hassle in return for discounts of up to 80% off regular fares.
The CRD Mixer has helical, wedge-shaped mixing and wiping flights. The mixing flights are lower, with a curved or slanted leading flank that forces the melt over the flights and creates elongational stresses.