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flight

 
(flīt) pronunciation
n.
    1. The motion of an object in or through a medium, especially through the earth's atmosphere or through space.
    2. An instance of such motion.
    3. The distance covered in such motion.
    1. The act or process of flying through the air by means of wings.
    2. The ability to fly.
  1. A swift passage or movement.
  2. A scheduled airline run or trip.
  3. A group, especially of birds or aircraft, flying together. See synonyms at flock1.
  4. A number of aircraft in the U.S. Air Force forming a subdivision of a squadron.
  5. A round of competition, as in a sports tournament.
  6. An exuberant or transcendent effort or display: a flight of the imagination; flights of oratory.
  7. A series of stairs rising from one landing to another.
intr.v., flight·ed, flight·ing, flights.
To migrate or fly in flocks.

[Middle English, from Old English flyht.]


flight2 (flīt) pronunciation
n.
The act or an instance of running away; an escape.

[Middle English, from Old English *flyht.]


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Movement through the atmosphere or space, sustained by aerodynamic reaction or other forces. Animal flight includes gliding and flapping flight. Flapping flight in vertebrates was probably preceded by gliding; in insects it may have originated by leaping and gliding, by surface skimming on water, or (if small enough) by passive floating in the air. Flying insects show greater variation than flying vertebrates, and their flight spans a wider range of Reynolds numbers, which is the ratio of inertial forces to viscous forces in the flow. Flight of tiny insects is in the lower range of Reynolds numbers, where viscous forces are dominant, whereas large insects and vertebrates operate in the higher range, where inertial forces are important.

Flight is very expensive in terms of energy cost per unit time. However, flying animals can travel several times faster than nonflying ones, and the cost of carrying a unit of weight of an animal through a unit distance (cost of transport) is lower for flight than for running, but higher than for swimming.

The flight characteristics of large insects and vertebrates can be understood by aircraft aerodynamics. In steady level flight, an animal and an aircraft must generate forces that support weight against gravity and provide propulsive thrust against drag forces. The forces acting on an airfoil (the shape of the cross section of the wings) moving through the air depend upon the flow pattern around it. Because of the asymmetric profile on an airfoil, the air flowing over the upper surface travels farther and flows faster than air passing underneath. According to Bernoulli's principle, pressure falls when speed rises in a moving fluid, resulting in a pressure difference between the upper and lower sides of the airfoil (illus. a). This pressure difference has to disappear gradually toward the wingtips, and some air will flow upward around the wingtips. The air moves downward behind the wing as trailing vortices (illus. b), and the reaction of this momentum flow is experienced by the wing as lift. The stronger the vortex, the greater the lift generated, but with some energy loss to drag. The lift force is responsible for weight support (its vertical component) and thrust or drag (its horizontal component). See also Aerodynamic force; Airfoil; Bernoulli's theorem.

Aerodynamics of flight. (<i>a</i>) Airflow around a typical wing profile. (<i>b</i>) Pressure distribution around a typical wing profile. (<i>c</i>) The difference in pressure disappears toward the wingtips as trailing vortices in the wake. (<i>After M. Brooke and T. Birkhead, eds., Cambridge Encyclopedia of Ornithology, Cambridge University Press, 1991</i>)
Aerodynamics of flight. (a) Airflow around a typical wing profile. (b) Pressure distribution around a typical wing profile. (c) The difference in pressure disappears toward the wingtips as trailing vortices in the wake. (After M. Brooke and T. Birkhead, eds., Cambridge Encyclopedia of Ornithology, Cambridge University Press, 1991)

Energy must be expended to generate the trailing vortices in the wake and to overcome friction on the wing and body surfaces. These energy losses are experienced as drag forces, which act parallel to the direction of movement of the airfoil. Since drag is a retarding force, the animal must either descend (glide) through the air at such an angle that a component of its weight balances the drag, or do mechanical work with its flight muscles (flap its wings) to overcome it. The rate at which this work is done is the mechanical power required to fly, and it equals speed times drag (measured in watts). The flight muscles also produce heat when they contract, so the total metabolic power expenditure is the sum of this heat loss and the mechanical power. The metabolic power is estimated to be four to five times the mechanical power, and is dependent on the size of the animal. See also Work.

Compared with active flight, gliding flight is very inexpensive, and is found in a wide range of animals, such as squirrels, marsupials, lizards, frogs, fishes, and even one snake. It is the main component in soaring flight used by many birds and some bats, when the animals use thermals or updrafts. Gliding in birds costs only two to three times the basal metabolic rate, because the flight muscles do not perform any mechanical work other than for stability and control of movements, and produce mostly static forces to keep the wings down on the horizontal plane, opposing the aerodynamic force.

When gliding, the wings of the animal leave behind a continuous vortex sheet that rolls up into a pair of vortex tubes (wingtip vortices), as in fixed-wing airplanes (illus. b). The lift produced balances the animal's weight, but potential energy must be used to overcome the drag and the animal loses height. An animal gliding at steady speed descends at an angle to the horizontal (glide angle), established by the ratio of lift to drag (glide ratio). The best glide ratios in birds range from 10:1 to 15:1 for vultures and birds of prey and reach 23:1 in the wandering albatross, whereas modern gliders can achieve 45:1. An animal cannot glide more slowly than its stalling speed, which in birds can be reduced by splaying the wingtip primaries, or by spreading the alula (a digit of the wing) at the wrist, or both. An animal can increase its gliding speed by flexing the wings and reducing the wing area.

Hovering flight represents the most expensive form of animal flapping flight. The essence of hovering is to produce a vertical force to balance body weight. The wake consists of a chain of vortex rings continuously shed during the wing strokes. In hummingbirds and insects, lift is produced during both the downstroke and upstroke of the wings (symmetrical hovering), and two vortex rings are produced during each wing stroke. In other hovering animals the wings are flexed during the upstroke (asymmetrical hovering), and the rings are produced during the downstrokes only. See also Aerodynamics; Aves.


1. Term used in media scheduling that indicates the length of the advertising period. Typically, an advertising campaign runs for a specified number of weeks, followed by a period of inactivity, and then is resumed. Each activity period is known as a flight. This spacing prevents overexposure to the advertisement or commercial without allowing the message to be forgotten. It also reduces media expenditures.

2. Part of a promotional campaign conducted in segments over time, such as a direct-mail advertising campaign with a series of drops.

Each flight in a direct-mail campaign is generally larger than the previous one and is not mailed until the success of the previous flight is confirmed. The final and largest mailing is called the roll out. See also flash count; pyramiding; weigh count.

Roget's Thesaurus:

flight

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noun

    The act or an instance of escaping, as from confinement or difficulty: break, breakout, decampment, escape, escapement, getaway. Slang lam. See free/unfree.


n

Definition: fleeing; departure
Antonyms: standing, staying, waiting

When people before the Montgolfier brothers thought of human flight, they pictured birds. Leonardo da Vinci was one of the few who proposed a different concept, the helicopter. But early in the 17th century the barometer was invented by Evangelista Torricelli, and Blaise Pascal used it to show that not only does air have weight, but also air density decreases with altitude. Soon the Jesuit monk Francesco de Lana realized that an evacuated globe should float on the heavier air. A Dominican friar, Joseph Galien, pictured capturing less dense air from the top of a mountain and dragging it downhill until it reached a level that would cause a craft attached to it to float. These impractical schemes embodied the idea that flight could be accomplished by the quiet mechanism that buoys a ship in water instead of by frantic activity.

Joseph and Jacques Etienne Montgolfier came from a family of paper makers, so it should come as no surprise that their idea for flight would be realized in paper. All accounts credit older brother Joseph with the original notion, but differ on whether it was inspired by watching bits of burning paper fly into the sky or by reading about experiments that described different gases with different weights. The brothers are thought never to have understood that a hot-air balloon floats because warm air is less dense than cold air. Instead, they believed that burning produced a gas different from air that was also lighter than air. In any case, Joseph began in 1783 with a small paper balloon filled with hot air by holding it over a fire. A stronger silk balloon, similarly inflated, rose to about 21 m (70 ft). By June 4 of that year the brothers had made a sphere 11 m (36 ft) in diameter of linen lined with their family's paper to retain the gas. Their first public demonstration was in Annonay, France, south of Lyon and west of Grenoble. The balloon rose to a considerable height and floated in the air for ten minutes, coming down about 2.4 km (1.5 mi) away from the launch site. On landing, however, the fire suspended below the balloon lit the paper and the balloon burned. Word of this experiment quickly reached Paris. A public fund was set up in Paris to have a local scientist, Jacques Charles, duplicate the Montgolfier feat.

Charles, however, did not know how the Montgolfiers got their balloon to fly. He had been experimenting with hydrogen, which he knew to be lighter than air. Therefore, he began constructing a hydrogen balloon. He had to produce thousands of times as much free hydrogen as had ever been previously made -- hydrogen had been known for less than 20 years. Charles and his assistants managed not to blow themselves up and succeeded in conducting the semipublic experiment -- you had to have a ticket to get close to the 3.6-m (12-ft) balloon. When released, it shot straight up and quickly disappeared.

In the meantime, Jacques Etienne Montgolfier was also in Paris trying to arrange for a public demonstration of his own. He secured the support of Louis XVI and funding from the government. The second full-size hot-air balloon was 21 m (70 ft) tall, 12 m (40 ft) wide, and decorated like 18th-century wallpaper. This was because It was constructed with the help of another paper manufacturer, Jean-Baptiste Révillon, who made wallpaper. Unfortunately, the first attempt to fly the balloon ended in disaster when heavy rain dissolved the wallpaper. A third balloon was built, this time from taffeta coated with varnish. This balloon carried a sheep, a rooster, and a duck for about two miles in about eight minutes, landing gently enough not to harm the animals.

Competition now developed between the Montgolfier team and the Charles team to get the first human aloft. Although there are hints that the Montgolfier team might have achieved this even earlier, they definitely won with a public launch on the outskirts of Paris. François Pilâtre de Rozier and the Marquis 'd'Arlandes flew across Paris for over 20 minutes, but then lost their nerve and let the fire die so that the vehicle would descend. Ten days later, Charles and a member of his team made the first hydrogen balloon flight. But it was too late. The Montgolfiers would always be known as the people who gave humanity flight.

Before the end of 1783, several humans had made their first flights in hot-air balloons, sometimes called Montgolfieres, and also in Charles's hydrogen-filled devices. But it was not until January 10, 1784, that a Montgolfier brother ascended -- Joseph was part of a successful flight in Lyon that included six other passengers. That was the only trip for Joseph, and Jacques-Etienne never did fly.

n. 1. the movement or trajectory of a projectile through the air.

2. a group of aircraft operating together, especially an air force unit of about six aircraft: a refueling mission in which his crew topped off three flights of four F-16A jets.

3. the action of fleeing or attempting to escape: refugees on the latest stage of their flight from turmoil.

in full flight escaping as fast as possible.

put someone/something to flight cause someone or something to flee:

a soldier who held off, and eventually put to flight, waves of attackers.

See the Introduction, Abbreviations and Pronunciation for further details.

A continuous series of steps with no intermediate landings.


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. 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.


Any leaving or self-concealment to avoid arrest or prosecution after arrest; 184 A. 2d 321, 323; the act of leaving the scene of the crime, done by one who feels guilt, in order to avoid arrest. See also abscond, fugitive from justice.

An advertising scheduling strategy in which a business alternates between running a normal schedule of advertising and a complete cessation of all runs. A company may use a flighting strategy as a way to save on advertising costs, while relying on the effect of its past advertisements continue to drive sales. As sales slow or more budget becomes available, the company will resume normal advertising.

Investopedia Says:
Flighting is most commonly associated with television advertising, but can also be used with other media types, such as radio or the internet. It rose to prominence, along with another strategy, "pulsing", as advertising rates grew faster than advertising budgets. With this strategy, companies must balance potential customers' ability to recall a product or service with the cost of constantly reaching them. The longer the recall period, the less necessary it may be to run as many advertisements.

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(DOD) 1. In Navy and Marine Corps usage, a specified group of aircraft usually engaged in a common mission. 2. The basic tactical unit in the Air Force, consisting of four or more aircraft in two or more elements. 3. A single aircraft airborne on a nonoperational mission.

Word Tutor:

flight

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pronunciation

IN BRIEF: A trip through the air, as by an airplane or bird.

pronunciation Their flight was delighted because of the storm.

LearnThatWord.com is a free vocabulary and spelling program where you only pay for results!

sign description: The sign for FLY is used yet it's movement is slower and a facial expression of pursed lips accompanies the sign indicating a longer 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 human-controlled 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.

Random House Word Menu:

categories related to 'flight'

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Random House Word Menu by Stephen Glazier
For a list of words related to flight, see:

  See crossword solutions for the clue Flight.
A hummingbird in flight
A Barn Swallow in flight

Flight is the process by which an object moves, through an atmosphere (especially the air) or beyond it (as in the case of spaceflight), by generating aerodynamic lift, propulsive thrust, aerostatically using buoyancy, or by ballistic movement, without any direct mechanical support from the ground.

The engineering aspects of flight is studied in aerospace engineering which is subdivided into aeronautics, which is the study of vehicles that travel through the air, and astronautics, the study of vehicles that travel through space.

Contents

Types of Flight

Buoyant flight

A blimp flies because the upward force is equal or greater than the force of gravity.

Humans have managed to construct lighter than air vehicles that raise off the ground and fly, due to their buoyancy in air and water.

An aerostat is a system that remains aloft primarily through the use of buoyancy to give an aircraft that has the same overall density as air. Aerostats include free balloons, airships, and moored balloons. An aerostat's main structural component is its envelope, a lightweight skin containing a lifting gas[1][2] to provide buoyancy, to which other components are attached.

Aerostats are so named because they use "aerostatic" lift, a buoyant force that does not require lateral movement through the surrounding air mass. By contrast, aerodynes primarily use aerodynamic lift, which requires the lateral movement of at least some part of the aircraft through the surrounding air mass.

Aerodynamic flight

Unpowered flight versus powered flight

Some things that fly do not generate propulsive thrust through the air, for example, the flying squirrel. This is termed gliding. Some other things can exploit rising air to climb such as raptors (when gliding) and man-made gliders. This is termed soaring. However most other birds and all powered aircraft need a source of propulsion to climb. This is termed powered flight.

Animal

Female Mallard Duck
Tau Emerald dragonfly

The only groups of living things that use powered flight are birds, insects, and bats, while many groups have evolved gliding. The extinct Pterosaurs, an order of reptiles contemporaneous with the dinosaurs, were also very successful flying animals. Each of these groups' wings evolved independently. The wings of the flying vertebrate groups are all based on the forelimbs, but differ significantly in structure; those of insects are hypothesized to be highly-modified versions of structures that form gills in most other groups of arthropods.[3]

Bats are the only mammals capable of sustaining level flight.[4] However, there are several gliding mammals which are able to glide from tree to tree using fleshy membranes between their limbs; some can travel hundreds of meters in this way with very little loss in height. Flying frogs use greatly enlarged webbed feet for a similar purpose, and there are flying lizards which fold out their mobile ribs into a pair of flat gliding surfaces. "Flying" snakes also use mobile ribs to flatten their body into an aerodynamic shape, with a back and forth motion much the same as they use on the ground.

Flying fish can glide using enlarged wing-like fins, and have been observed soaring for hundreds of meters. It is thought that this ability was chosen by natural selection because it was an effective means of escape from underwater predators. The longest recorded flight of a flying fish was 45 seconds.[5]

Most birds fly (see bird flight), with some exceptions. The largest birds, the Ostrich and the Emu, are earthbound, as were the now-extinct Dodos and the Phorusrhacids, which were the dominant predators of South America in the Cenozoic era. The non-flying penguins have wings adapted for use under water and use the same wing movements for swimming that most other birds use for flight.[citation needed] Most small flightless birds are native to small islands, and lead a lifestyle where flight would confer little advantage.

Among living animals that fly, the Wandering Albatross has the greatest wingspan, up to 3.5 meters (11.5 ft); the Great Bustard has the greatest weight, topping at 21 kilograms (46 pounds).[6]

Many species of insects also fly (See insect flight).

Mechanical

Mechanical flight: A Robinson R22 Beta helicopter

Mechanical flight is the use of a machine to fly. These machines include aircraft such as airplanes, gliders, helicopters, autogyros, airships, balloons, ornithopters as well as spacecraft. Gliders are capable of unpowered flight. Another form of mechanical flight is para-sailing where a parachute-like object is pulled by a boat. In an airplane, lift is created by the wings; the shape of the wings of the airplane are designed specially for the type of flight desired. There are different types of wings: tempered, semi-tempered, sweptback, rectangular and elliptical. An aircraft wing is sometimes called an airfoil, which is a device that creates lift when air flows across it.

Supersonic

Supersonic flight is flight faster than the speed of sound. Supersonic flight is associated with the formation of shock waves that form a sonic boom that can be heard from the ground, and is frequently startling. This shockwave takes quite a lot of energy to create and this makes supersonic flight generally less efficient than subsonic flight at about 85% of the speed of sound.

Hypersonic

Hypersonic flight is very high speed flight where the heat generated by the compression of the air due to the motion through the air causes chemical changes to the air. Hypersonic flight is achieved by reentering spacecraft such as the Space Shuttle and Soyuz.

Ballistic

Atmospheric

Some things generate little or no lift and move only or mostly under the action of momentum, gravity, air drag and in some cases thrust. This is termed ballistic flight. Examples include balls, arrows, bullets, fireworks etc.

Spaceflight

Essentially an extreme form of ballistic flight, spaceflight is the use of space technology to achieve the flight of spacecraft into and through outer space. Examples include ballistic missiles, orbital spaceflight etc.

Spaceflight is used in space exploration, and also in commercial activities like space tourism and satellite telecommunications. Additional non-commercial uses of spaceflight include space observatories, reconnaissance satellites and other earth observation satellites.

A spaceflight typically begins with a rocket launch, which provides the initial thrust to overcome the force of gravity and propels the spacecraft from the surface of the Earth. Once in space, the motion of a spacecraft—both when unpropelled and when under propulsion—is covered by the area of study called astrodynamics. Some spacecraft remain in space indefinitely, some disintegrate during atmospheric reentry, and others reach a planetary or lunar surface for landing or impact.

History

Aviation

Leonardo da Vinci is one of the best-known early students of flight. He made many drawings of parachutes wings, helicoptes and ornithopters.

Otto Lillienthal made over 200 gliding flights and was one of the first to understand flight scientifically. His work was replicated and extended by the Wright brothers who made gliding flights and finally the first controlled and extended, manned powered flights.[7]

Spaceflight

Spaceflight, particularly human spaceflight became a reality in the 20th Century following theoretical and practical breakthroughs by Konstantin Tsiolkovsky and Robert H. Goddard.

Physics

Lighter-than-air Airships are able to fly without any major input of energy

There are different approaches to flight. If an object has a lower density than air, then it is buoyant and is able to float in the air without using energy. A heavier than air craft, known as an aerodyne, includes flighted animals and insects, fixed-wing aircraft and rotorcraft. Because the craft is heavier than air, it must generate lift to overcome its weight. The wind resistance caused by the craft moving through the air is called drag and is overcome by propulsive thrust except in the case of gliding.

Some vehicles also use thrust for flight, for example rockets and Harrier Jump Jets.

Forces

Main forces on a heavier-than-air aircraft

Forces relevant to flight are[8]

These forces must be balanced for stable flight to occur.

Lift

In the context of an air flow relative to a flying body, the lift force is the component of the aerodynamic force that is perpendicular to the flow direction.[9] It contrasts with the drag force, which is the parallel component of the aerodynamic force. In all cases, aerodynamic lift is associated with pressures on the wing that sum over the area of the flight surfaces to create the lift force, and there is a net movement of air in the opposite direction from the force which is indirectly created by these pressures, in accordance with Newton's third law of motion.

Lift is commonly associated with the wing of an aircraft, although lift is also generated by rotors on rotorcraft. While common meanings of the word "lift" suggest that lift opposes gravity, aerodynamic lift can be in any direction. When an aircraft is in cruise for example, lift does oppose gravity, but occurs at an angle when climbing, descending or banking.

Lift can also occur in a different way if the air is not still, especially if there is an updraft due to heat ("thermals") or wind blowing along sloping terrain or other meteorological conditions. This form of lift permits soaring and is particularly important for gliding. It is used by birds and gliders to stay in the air for long periods with little effort.

Drag

For a solid object moving through a fluid, the drag is the component of the net aerodynamic or hydrodynamic force acting opposite to the direction of the movement. The component perpendicular to this direction is considered lift. Therefore drag opposes the motion of the object, and in a powered vehicle it is overcome by thrust.

Lift-to-drag ratio

Speed and drag relationships for a typical flight article

When lift is created by the motion of an object through the air, this deflects the air, and this is the source of lift. For sustained level flight lift must be equal to weight.

However, this lift inevitably causes some drag also, and it turns out that the efficiency of lift creation can be associated with a lift-to-drag ratio for a vehicle; the lift-to-drag ratios are approximately constant over a wide range of speeds.

Lift-to-drag ratios for practical aircraft vary from about 4:1 up to 60:1 or more. The lower ratios are generally for vehicles and birds with relatively short wings, and the higher ratios are for vehicles with very long wings, such as gliders. In general, long wings permit a large amount of air to be deflected and accelerated by a small amount, rather than a small amount of air by a large amount. Since energy is a square law on deflection speed, whereas lift is a linear relation, it takes less energy, and less drag is created, with large wings.

Thrust to weight ratio

Thrust-to-weight ratio is, as its name suggests, the ratio of instantaneous thrust to weight (where weight means weight at the Earth’s standard acceleration g0).[10] It is a dimensionless parameter characteristic of rockets and other jet engines and of vehicles propelled by such engines (typically space launch vehicles and jet aircraft).

If the thrust-to-weight ratio is greater than the local gravity strength (expressed in gs), then flight can occur without any forward motion or any aerodynamic lift being required.

If the thrust-to-weight ratio times the lift-to-drag ratio is greater than local gravity then takeoff using aerodynamic lift is possible.

Flight dynamics

The upward tilt of the wings and tailplane of an aircraft, as seen on this Boeing 737, is called dihedral angle

Flight dynamics is the science of air and space vehicle orientation and control in three dimensions. The three critical flight dynamics parameters are the angles of rotation in three dimensions about the vehicle's center of mass, known as pitch, roll and yaw (See Tait-Bryan rotations for an explanation).

The control of these dimensions can involve a horizontal stabilizer (i.e. "a tail"), ailerons and other movable aerodynamic devices which control angular stability i.e. flight attitude (which in turn affects altitude, heading). Wings are often angled slightly upwards- they have "positive dihedral angle" which gives inherent roll stabilization.

Energy efficiency

To create thrust so as to be able to gain height, and to push through the air to overcome the drag associated with lift all takes energy. Different objects and creatures capable of flight vary in the efficiency of their muscles, motors and how well this translates into forward thrust.

Propulsive efficiency determines how much energy vehicles gain from a unit of fuel.

Range

The range that powered flight articles can achieve is ultimately limited by their drag, as well as how much energy they can store on-board.

For powered aircraft the useful energy is determined by their fuel fraction- what percentage of the takeoff weight is fuel, as well as the specific energy of the fuel used.

Power-to-weight ratio

All animals and devices capable of sustained flight need relatively high power-to-weight ratios to be able to generate enough lift and/or thrust to achieve take off.

Takeoff and landing

Vehicles that can fly can have different ways to takeoff and land. Conventional aircraft accelerate along the ground until sufficient lift is generated for takeoff, and reverse the process for landing. Some aircraft can takeoff at low speed, this a short takeoff. Some aircraft such as helicopters and Harrier jump jets can takeoff and land vertically. Rockets also usually takeoff and land vertically, but some designs can land horizontally.

Guidance, Navigation and Control

Guidance

A guidance system is a device or group of devices used to navigate a ship, aircraft, missile, rocket, satellite, or other craft. Typically, this refers to a system that navigates without direct or continuous human control. Systems that are intended to have a high degree of human interaction are usually referred to as a navigation system.

Navigation

In aircraft, successful air navigation involves piloting an aircraft from place to place without getting lost, breaking the laws applying to aircraft, or endangering the safety of those on board or on the ground.

The techniques used for navigation in the air will depend on whether the aircraft is flying under the visual flight rules (VFR) or the instrument flight rules (IFR). In the latter case, the pilot will navigate exclusively using instruments and radio navigation aids such as beacons, or as directed under radar control by air traffic control. In the VFR case, a pilot will largely navigate using dead reckoning combined with visual observations (known as pilotage), with reference to appropriate maps. This may be supplemented using radio navigation aids.

Control

Flight

A conventional fixed-wing aircraft flight control system consists of flight control surfaces, the respective cockpit controls, connecting linkages, and the necessary operating mechanisms to control an aircraft's direction in flight. Aircraft engine controls are also considered as flight controls as they change speed.

Traffic

In the case of aircraft, air traffic is controlled by air traffic control systems.

Collision avoidance is the process of controlling spacecraft to try to prevent collisions.

Flight safety

Air safety is a term encompassing the theory, investigation and categorization of flight failures, and the prevention of such failures through regulation, education and training. It can also be applied in the context of campaigns that inform the public as to the safety of air travel.

See also

References

  1. ^ The Chambers Dictionary. Edinburgh: Chambers Harrap Publishers Ltd., 2000, First edition 1998, p. 541 ISBN: 0-550-14005-X. Quote: the gas-bag of a balloon or airship.
  2. ^ The Oxford Illustrated Dictionary. Oxford, UK: Oxford University Press, 1976, First edition 1975, p. 281. Quote: fabric enclosing gas-bags of airship.
  3. ^ Averof, Michalis. "Evolutionary origin of insect wings from ancestral gills." Nature, Issue 385, volume 385, February 1997 pp. 627–630.
  4. ^ World Book Student. Chicagon: World Book. Retrieved: April 29, 2011.
  5. ^ "BBC article and video of flying fish." BBC, May 20, 2008. Retrieved: May 20, 2008.
  6. ^ "Swan Identification." The Trumpeter Swan Society. Retrieved: January 3, 2012.
  7. ^ Orville Wright's Personal Letters on Aviation. Chicago: Shapell Manuscript Foundation, 2012.
  8. ^ "Four forces on an aeroplane." NASA. Retrieved: January 3, 2012.
  9. ^ NASA's definition of lift
  10. ^ Rocket propulsion elements- George P. Sutton Oscar Biblarz (7th edition pg 442) "thrust-to-weight ratio F/W0 is a dimensionless parameter that is identical to the acceleration of the rocket propulsion system (expressed in multiples of g0) if it could fly by itself in a gravity free vacuum"

External links

video provided by the Vega Science Trust.


Translations:

Flight

Top

Dansk (Danish)
1.
n. - flyvning, flugt, flok, trappe, skarp rejsning
v. tr. - variere boldafleveringen, sætte styrefjer på
v. intr. - flyve i flok

idioms:

  • flight deck    cockpit
  • flight lieutenant    kaptajn (løjtnant)
  • flight of fancy    fiks ide
  • flight path    flyvevej
  • flight recorder    black box, flyets automatiske logbog
  • put to flight    jage på flugt
  • take flight    tage flugten

2.
n. - flugt

idioms:

  • take to flight    tage flugten

Nederlands (Dutch)
vlucht, vliegreis, snelle beweging, deel v. een eskadron, snelle voorbijgang (van tijd), salvo, route van een kogel etc., trap, pijlstaart, zwerm, vliegen in een zwerm

Français (French)
1.
n. - (Aérosp, Aviat, Transp) vol, vol (d'oiseaux), trajectoire (d'un missile), (Sport) série (de haies), (gén) élans (d'imagination), envolées (oratoires), volée (d'oiseaux), volée (de marches)
v. tr. - lancer/envoyer un ballon dans le mille, empenner (une flèche)
v. intr. - voler en mouvements coordonnées (des oiseaux), envoyer un ballon dans le mille

idioms:

  • flight deck    (Aviat) poste de pilotage, navigants techniques, (Naut) pont d'envol
  • flight lieutenant    (Mil) capitaine (de l'armée de l'air)
  • flight of fancy    vol d'agrément
  • flight path    route de vol
  • flight recorder    enregistreur de vol
  • put to flight    mettre en vol
  • take flight    prendre vol

2.
n. - fuite

idioms:

  • take to flight    prendre la fuite

Deutsch (German)
1.
n. - Flug, Schwarm
v. - (sport) einen Ball einwerfen, mit Federn versehen, in Schwärmen fliegen

idioms:

  • flight deck    Flugdeck, Cockpit
  • flight lieutenant    Hauptmann der Luftwaffe
  • flight of fancy    Illusion, Einbildung
  • flight path    Flugbahn
  • flight recorder    Flugschreiber
  • put to flight    in die Flucht schlagen
  • take flight    die Flucht ergreifen

2.
n. - Flucht

idioms:

  • take to flight    die Flucht ergreifen

Ελληνική (Greek)
n. - πτήση, πέταγμα, φυγή, (οικοδ.) σκάλα, σμήνος, διαδρομή (με αεροπλάνο)
attrib. - της πτήσης

idioms:

  • flight deck    (ναυτ.) κατάστρωμα απογειώσεως αεροπλανοφόρου
  • flight lieutenant    (στρατ.) σμηναγός
  • flight of fancy    φαντασίωση
  • flight path    πορεία/τροχιά πτήσεως
  • flight recorder    (τεχνολ.) όργανο καταγραφής των τεχνικών στοιχείων πτήσεως (κν. μαύρο κουτί)
  • put to flight    τρέπω σε (άτακτη) φυγή
  • take flight    τρέπομαι σε φυγή, λακίζω

Italiano (Italian)
volo, fuga, scalinata, sciame, stormo, esilio

idioms:

  • flight deck    ponte di decollo
  • flight lieutenant    tenente pilota
  • flight of fancy    volo di fantasia
  • flight path    rotta di volo
  • flight recorder    registratore di volo
  • put to flight    provocare la fuga
  • take flight    darsi alla fuga

Português (Portuguese)
n. - vôo (m), bando (de aves) (m), fuga (f)

idioms:

  • flight deck    cabine (f) de comando de avião
  • flight lieutenant    capitão-voador (m) (Força Aérea Britânica)
  • flight of fancy    devaneio
  • flight path    trajetória de vôo
  • flight recorder    caixa (f) preta do avião
  • put to flight    botar para correr (gír.)
  • take flight    fugir

Русский (Russian)
полет, перелет, рейс, быстрое течение времени, порыв, отряд самолетов, лестничный пролет, побег, утечка

idioms:

  • flight deck    кабина экипажа, полетная палуба
  • flight lieutenant    капитан авиации (Великобритания)
  • flight of fancy    полет фантазии
  • flight path    курс полета
  • flight recorder    бортовой самописец
  • put to flight    прогнать
  • take flight    сбежать

Español (Spanish)
1.
n. - recorrido, trayectoria, vuelo, viaje en avión, escuadrilla, bandada, enjambre, descarga, tramo de escalera
v. tr. - tirar una pelota en forma precisa, emplumar
v. intr. - volar en bandada

idioms:

  • flight deck    cubierta de aterrizaje, cabina de mando/piloto
  • flight lieutenant    capitán de la Fuerza Aérea
  • flight of fancy    vuelo de la imaginación
  • flight path    trayectoria de vuelo
  • flight recorder    caja negra (del avión)
  • put to flight    poner en fuga
  • take flight    huir

2.
n. - huida, evasión, fuga

idioms:

  • take to flight    darse a la fuga

Svenska (Swedish)
n. - flykt, flygning
attr. - flyg-

中文(简体)(Chinese (Simplified))
飞行, 飞跃, 逃走, 飞机, 班次, 搭机旅行, 射击, 使惊飞, 成群飞行, 迁徙

idioms:

  • flight deck    航空母舰的飞行甲板
  • flight lieutenant    空军上尉
  • flight of fancy    奇想, 胡思乱想
  • flight path    飞行路线, 航线
  • flight recorder    飞行记录器
  • put to flight    击溃
  • take flight    失败逃跑

中文(繁體)(Chinese (Traditional))
1.
n. - 飛行
v. tr. - 射擊, 使驚飛
v. intr. - 遷徙

idioms:

  • flight deck    航空母艦的飛行甲板
  • flight lieutenant    空軍上尉
  • flight of fancy    奇想, 胡思亂想
  • flight path    飛行路線, 航線
  • flight recorder    飛行記錄器
  • put to flight    擊潰
  • take flight    失敗逃跑

2.
n. - 飛行, 飛躍, 逃走, 飛機, 班次, 搭機旅行

한국어 (Korean)
1.
n. - 날기, 비행기 여행, 비약
v. tr. - (스포츠에서) 공을 정확하게 던지거나 차다, 깃털을 붙이다
v. intr. - 떼지어 날다

idioms:

  • put to flight    패주 시키다
  • take flight    도망치다

2.
n. - 도주 탈출

idioms:

  • take to flight    도망치다

日本語 (Japanese)
n. - 飛ぶこと, 飛行, 飛行距離, 便, 飛行機, 早い経過, 速い動き, 群れ, 一団, 敗走, 定期便, 操縦法, 経過, 一続きの階段

idioms:

  • flight deck    飛行甲板, フライトデッキ
  • flight lieutenant    航空大尉
  • flight of fancy    現実とかけ離れた空想
  • flight of stairs    階段, ひと続きの階段
  • flight path    飛行経路
  • flight recorder    フライトレコーダー
  • put to flight    敗走させる
  • scheduled flight    定期便
  • take flight    逃げる

العربيه (Arabic)
‏(الاسم) طيران , رحله جويه (صفه) طيران‏

עברית (Hebrew)
n. - ‮טיסה, תעופה, להקה, התעלות, מנוסה, בריחה, גף, מערכת מדרגות‬
v. intr. - ‮חיבר נוצות לראש-חץ, ירה בציפורים באוויר‬
n. - ‮מנוסה, בריחה‬


 
 

 

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