wingtip vortices
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Wingtip vortices are circular patterns of rotating air left behind a
wing A wing is a type of fin that produces lift while moving through air or some other fluid. Accordingly, wings have streamlined cross-sections that are subject to aerodynamic forces and act as airfoils. A wing's aerodynamic efficiency is expres ...
as it generates
lift Lift or LIFT may refer to: Physical devices * Elevator, or lift, a device used for raising and lowering people or goods ** Paternoster lift, a type of lift using a continuous chain of cars which do not stop ** Patient lift, or Hoyer lift, mobil ...
.Clancy, L.J., ''Aerodynamics'', section 5.14 One wingtip
vortex In fluid dynamics, a vortex ( : vortices or vortexes) is a region in a fluid in which the flow revolves around an axis line, which may be straight or curved. Vortices form in stirred fluids, and may be observed in smoke rings, whirlpools in th ...
trails from the
tip Tip commonly refers to: * Tip (gambling) * Tip (gratuity) * Tip (law enforcement) * another term for Advice (opinion), Advice Tip or TIP may also refer to: Science and technology * Tank phone, a device allowing infantry to communicate with the oc ...
of each wing. Wingtip vortices are sometimes named ''trailing'' or ''lift-induced vortices'' because they also occur at points other than at the wing tips. Indeed, vorticity is trailed at any point on the wing where the lift varies span-wise (a fact described and quantified by the
lifting-line theory The Prandtl lifting-line theory is a mathematical model in aerodynamics that predicts lift distribution over a three-dimensional wing based on its geometry. It is also known as the Lanchester–Prandtl wing theory. The theory was expressed indepen ...
); it eventually rolls up into large vortices near the wingtip, at the edge of flap devices, or at other abrupt changes in wing planform. Wingtip vortices are associated with
induced drag In aerodynamics, lift-induced drag, induced drag, vortex drag, or sometimes drag due to lift, is an aerodynamic drag force that occurs whenever a moving object redirects the airflow coming at it. This drag force occurs in airplanes due to wings or ...
, the imparting of
downwash In aeronautics, downwash is the change in direction of air deflected by the aerodynamic action of an airfoil, wing, or helicopter rotor blade in motion, as part of the process of producing lift.Crane, Dale: ''Dictionary of Aeronautical Terms, thir ...
, and are a fundamental consequence of three-dimensional lift generation. Careful selection of wing geometry (in particular,
wingspan The wingspan (or just span) of a bird or an airplane is the distance from one wingtip to the other wingtip. For example, the Boeing 777–200 has a wingspan of , and a wandering albatross (''Diomedea exulans'') caught in 1965 had a wingspan of ...
), as well as of cruise conditions, are design and operational methods to minimize induced drag. Wingtip vortices form the primary component of
wake turbulence Wake turbulence is a disturbance in the atmosphere that forms behind an aircraft as it passes through the air. It includes variety of elements, the most significant of which are wingtip vortices and jetwash. Jetwash refers to the rapidly moving g ...
. Depending on ambient atmospheric humidity as well as the geometry and wing loading of aircraft, water may condense or freeze in the core of the vortices, making the vortices visible.


Generation of trailing vortices

When a wing generates
aerodynamic lift A fluid flowing around an object exerts a force on it. Lift is the component of this force that is perpendicular to the oncoming flow direction. It contrasts with the drag force, which is the component of the force parallel to the flow direc ...
, it results in a region of downwash behind the aircraft, between the two vortices. Three-dimensional lift and the occurrence of wingtip vortices can be approached with the concept of
horseshoe vortex The horseshoe vortex model is a simplified representation of the vortex system present in the flow of air around a wing. This vortex system is modelled by the ''bound vortex'' (bound to the wing) and two '' trailing vortices'', therefore having ...
and described accurately with the Lanchester–Prandtl theory. In this view, the trailing vortex is a continuation of the ''wing-bound vortex'' inherent to the lift generation.


Effects and mitigation

Wingtip vortices are associated with
induced drag In aerodynamics, lift-induced drag, induced drag, vortex drag, or sometimes drag due to lift, is an aerodynamic drag force that occurs whenever a moving object redirects the airflow coming at it. This drag force occurs in airplanes due to wings or ...
, an unavoidable consequence of three-dimensional lift generation. The rotary motion of the air within the shed wingtip vortices (sometimes described as a "leakage") reduces the effective
angle of attack In fluid dynamics, angle of attack (AOA, α, or \alpha) is the angle between a reference line on a body (often the chord line of an airfoil) and the vector representing the relative motion between the body and the fluid through which it is m ...
of the air on the wing. The
lifting-line theory The Prandtl lifting-line theory is a mathematical model in aerodynamics that predicts lift distribution over a three-dimensional wing based on its geometry. It is also known as the Lanchester–Prandtl wing theory. The theory was expressed indepen ...
describes the shedding of trailing vortices as span-wise changes in lift distribution. For a given wing span and surface, minimal induced drag is obtained with an elliptical lift distribution. For a given lift distribution and wing planform area, induced drag is reduced with increasing aspect ratio. As a consequence, aircraft for which a high
lift-to-drag ratio In aerodynamics, the lift-to-drag ratio (or L/D ratio) is the lift generated by an aerodynamic body such as an aerofoil or aircraft, divided by the aerodynamic drag caused by moving through air. It describes the aerodynamic efficiency under gi ...
is desirable, such as gliders or long-range
airliner An airliner is a type of aircraft for transporting passengers and air cargo. Such aircraft are most often operated by airlines. Although the definition of an airliner can vary from country to country, an airliner is typically defined as an ...
s, typically have high aspect ratio wings. Such wings however have disadvantages with respect to structural constraints and maneuverability, as evidenced by
combat Combat ( French for ''fight'') is a purposeful violent conflict meant to physically harm or kill the opposition. Combat may be armed (using weapons) or unarmed ( not using weapons). Combat is sometimes resorted to as a method of self-defense, or ...
and
aerobatic Aerobatics is the practice of flying maneuvers involving aircraft attitudes that are not used in conventional passenger-carrying flights. The term is a portmanteau of "aerial" and "acrobatics". Aerobatics are performed in aeroplanes and glid ...
planes which usually feature short, stubby wings despite the efficiency losses. Another method of reducing induced drag is the use of
winglets Wingtip devices are intended to improve the efficiency of fixed-wing aircraft by reducing drag. Although there are several types of wing tip devices which function in different manners, their intended effect is always to reduce an aircraft' ...
, as seen on most modern airliners. Winglets increase the effective aspect ratio of the wing, changing the pattern and magnitude of the
vorticity In continuum mechanics, vorticity is a pseudovector field that describes the local spinning motion of a continuum near some point (the tendency of something to rotate), as would be seen by an observer located at that point and traveling along wi ...
in the vortex pattern. A reduction is achieved in the kinetic energy in the circular air flow, which reduces the amount of fuel expended to perform work upon the spinning air. After NASA became concerned about the increasing density of air traffic potentially causing vortex related accidents at airports, an experiment by NASA Ames Research Center wind tunnel testing with a 747 model found that the configuration of the flaps could be changed on existing aircraft to break the vortex into three smaller and less disturbing vortexes. This primarily involved changing the settings of the outboard flaps, and could theoretically be retrofitted to existing aircraft.


Visibility of vortices

The cores of the vortices can sometimes be visible when the water present in them
condenses Condensation is the change of the state of matter from the gas phase into the liquid phase, and is the reverse of vaporization. The word most often refers to the water cycle. It can also be defined as the change in the state of water vapor to ...
from
gas Gas is one of the four fundamental states of matter (the others being solid, liquid, and plasma). A pure gas may be made up of individual atoms (e.g. a noble gas like neon), elemental molecules made from one type of atom (e.g. oxygen), or ...
(
vapor In physics, a vapor (American English) or vapour (British English and Canadian English; see spelling differences) is a substance in the gas phase at a temperature lower than its critical temperature,R. H. Petrucci, W. S. Harwood, and F. G. Her ...
) to
liquid A liquid is a nearly incompressible fluid that conforms to the shape of its container but retains a (nearly) constant volume independent of pressure. As such, it is one of the four fundamental states of matter (the others being solid, gas, a ...
. This water can sometimes even freeze, forming ice particles. Condensation of water vapor in wing tip vortices is most common on aircraft flying at high
angles of attack In fluid dynamics, angle of attack (AOA, α, or \alpha) is the angle between a reference line on a body (often the chord line of an airfoil) and the vector representing the relative motion between the body and the fluid through which it is ...
, such as fighter aircraft in high ''g'' maneuvers, or
airliner An airliner is a type of aircraft for transporting passengers and air cargo. Such aircraft are most often operated by airlines. Although the definition of an airliner can vary from country to country, an airliner is typically defined as an ...
s taking off and landing on humid days.


Aerodynamic condensation and freezing

The cores of vortices spin at very high speed and are regions of very low pressure. To first approximation, these low-pressure regions form with little exchange of heat with the neighboring regions (i.e., adiabatically), so the local temperature in the low-pressure regions drops, too.Green, S. I
"Wing tip vortices"
in ''Fluid vortices,'' S. I. Green, ed. (
Kluwer Wolters Kluwer N.V. () is a Dutch information services company. The company is headquartered in Alphen aan den Rijn, Netherlands (Global) and Philadelphia, United States (corporate). Wolters Kluwer in its current form was founded in 1987 with a m ...
, Amsterdam, 1995) pp. 427–470.
If it drops below the local
dew point The dew point is the temperature to which air must be cooled to become saturated with water vapor, assuming constant air pressure and water content. When cooled below the dew point, moisture capacity is reduced and airborne water vapor will cond ...
, there results a condensation of water vapor present in the cores of wingtip vortices, making them visible. The temperature may even drop below the local
freezing point The melting point (or, rarely, liquefaction point) of a substance is the temperature at which it changes state from solid to liquid. At the melting point the solid and liquid phase exist in equilibrium. The melting point of a substance depends ...
, in which case ice crystals will form inside the cores. The
phase Phase or phases may refer to: Science *State of matter, or phase, one of the distinct forms in which matter can exist *Phase (matter), a region of space throughout which all physical properties are essentially uniform * Phase space, a mathematic ...
of water (i.e., whether it assumes the form of a solid, liquid, or gas) is determined by its
temperature Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measured with a thermometer. Thermometers are calibrated in various temperature scales that historically have relied o ...
and
pressure Pressure (symbol: ''p'' or ''P'') is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled ''gage'' pressure)The preferred spelling varies by country and e ...
. For example, in the case of liquid-gas transition, at each pressure there is a special "transition temperature" T_ such that if the sample temperature is even a little above T_, the sample will be a gas, but, if the sample temperature is even a little below T_, the sample will be a liquid; see
phase transition In chemistry, thermodynamics, and other related fields, a phase transition (or phase change) is the physical process of transition between one state of a medium and another. Commonly the term is used to refer to changes among the basic states of ...
. For example, at the
standard atmospheric pressure The standard atmosphere (symbol: atm) is a unit of pressure defined as Pa. It is sometimes used as a ''reference pressure'' or ''standard pressure''. It is approximately equal to Earth's average atmospheric pressure at sea level. History The s ...
, T_ is 100 °C = 212 °F. The transition temperature T_ decreases with decreasing pressure (which explains why water boils at lower temperatures at higher altitudes and at higher temperatures in a
pressure cooker Pressure cooking is the process of cooking food under high pressure steam and water or a water-based cooking liquid, in a sealed vessel known as a ''pressure cooker''. High pressure limits boiling, and creates higher cooking temperatures which c ...
; see
here Here is an adverb that means "in, on, or at this place". It may also refer to: Software * Here Technologies, a mapping company * Here WeGo (formerly Here Maps), a mobile app and map website by Here Technologies, Here Television * Here TV (form ...
for more information). In the case of water vapor in air, the T_ corresponding to the
partial pressure In a mixture of gases, each constituent gas has a partial pressure which is the notional pressure of that constituent gas as if it alone occupied the entire volume of the original mixture at the same temperature. The total pressure of an ideal gas ...
of water vapor is called the
dew point The dew point is the temperature to which air must be cooled to become saturated with water vapor, assuming constant air pressure and water content. When cooled below the dew point, moisture capacity is reduced and airborne water vapor will cond ...
. (The solid–liquid transition also happens around a specific transition temperature called the
melting point The melting point (or, rarely, liquefaction point) of a substance is the temperature at which it changes state from solid to liquid. At the melting point the solid and liquid phase exist in equilibrium. The melting point of a substance depends ...
. For most substances, the melting point also decreases with decreasing pressure, although water ice in particular - in its Ih form, which is the most familiar one - is a prominent exception to this rule.) Vortex cores are regions of low pressure. As a vortex core begins to form, the water in the air (in the region that is about to become the core) is in vapor phase, which means that the local temperature is above the local dew point. After the vortex core forms, the pressure inside it has decreased from the ambient value, and so the local dew point (T_) has dropped from the ambient value. Thus, ''in and of itself'', a drop in pressure would tend to keep water in vapor form: The initial dew point was already below the ambient air temperature, and the formation of the vortex has made the local dew point even lower. However, as the vortex core forms, its pressure (and so its dew point) is not the only property that is dropping: The vortex-core temperature is dropping also, and in fact it can drop by much more than the dew point does. To first approximation, the formation of vortex cores is thermodynamically an
adiabatic process In thermodynamics, an adiabatic process (Greek: ''adiábatos'', "impassable") is a type of thermodynamic process that occurs without transferring heat or mass between the thermodynamic system and its environment. Unlike an isothermal process, ...
, i.e., one with no exchange of heat. In such a process, the drop in pressure is accompanied by a drop in temperature, according to the equation :\frac=\left(\frac\right)^. Here T_ and p_ are the
absolute temperature Thermodynamic temperature is a quantity defined in thermodynamics as distinct from kinetic theory or statistical mechanics. Historically, thermodynamic temperature was defined by Kelvin in terms of a macroscopic relation between thermodynamic wor ...
and pressure at the beginning of the process (here equal to the ambient air temperature and pressure), T_ and p_ are the absolute temperature and pressure in the vortex core (which is the end result of the process), and the constant \gamma is about 7/5 = 1.4 for air (see
here Here is an adverb that means "in, on, or at this place". It may also refer to: Software * Here Technologies, a mapping company * Here WeGo (formerly Here Maps), a mobile app and map website by Here Technologies, Here Television * Here TV (form ...
). Thus, even though the local dew point inside the vortex cores is even lower than in the ambient air, the water vapor may nevertheless condense — if the formation of the vortex brings the local temperature below the new local dew point. For a typical transport aircraft landing at an airport, these conditions are as follows: T_ and p_ have values corresponding to the so-called
standard conditions Standard temperature and pressure (STP) are standard sets of conditions for experimental measurements to be established to allow comparisons to be made between different sets of data. The most used standards are those of the International Union ...
, i.e., p_ = 1  atm = 1013.25  mb = 101\,325  Pa and T_ = 293.15  K (which is 20 °C = 68 °F). The
relative humidity Humidity is the concentration of water vapor present in the air. Water vapor, the gaseous state of water, is generally invisible to the human eye. Humidity indicates the likelihood for precipitation, dew, or fog to be present. Humidity depe ...
is a
comfortable Comfort (or being comfortable'')'' is a sense of physical or psychological ease, often characterized as a lack of hardship. Persons who are lacking in comfort are uncomfortable, or experiencing discomfort. A degree of psychological comfort c ...
35% (dew point of 4.1 °C = 39.4 °F). This corresponds to a
partial pressure In a mixture of gases, each constituent gas has a partial pressure which is the notional pressure of that constituent gas as if it alone occupied the entire volume of the original mixture at the same temperature. The total pressure of an ideal gas ...
of water vapor of 820 Pa = 8.2 mb. In a vortex core, the pressure (p_) drops to about 80% of the ambient pressure, i.e., to about 80 000 Pa. The temperature in the vortex core is given by the equation above as T_=\left(\frac\right)^\,T_= 0.935\,\times\,293.15=274\;\text, or 0.86 °C = 33.5 °F. Next, the partial pressure of water in the vortex core drops in proportion to the drop in the total pressure (i.e., by the same percentage), to about 650 Pa = 6.5 mb. According to a dew point calculator, that partial pressure results in the local dew point of about 0.86 °C; in other words, the new local dew point is about equal to the new local temperature. Therefore, this is a marginal case; if the relative humidity of the ambient air were even a bit higher (with the total pressure and temperature remaining as above), then the local dew point inside the vortices would rise, while the local temperature would remain the same. Thus, the local temperature would now be ''lower'' than the local dew point, and so the water vapor inside the vortices would indeed condense. Under the right conditions, the local temperature in vortex cores may drop below the local
freezing point The melting point (or, rarely, liquefaction point) of a substance is the temperature at which it changes state from solid to liquid. At the melting point the solid and liquid phase exist in equilibrium. The melting point of a substance depends ...
, in which case ice particles will form inside the vortex cores. The water-vapor condensation mechanism in wingtip vortices is thus driven by local changes in air pressure and temperature. This is to be contrasted to what happens in another well-known case of water condensation related to airplanes: the
contrail Contrails (; short for "condensation trails") or vapor trails are line-shaped clouds produced by aircraft engine exhaust or changes in air pressure, typically at aircraft cruising altitudes several miles above the Earth's surface. Contrails ar ...
s from airplane engine exhausts. In the case of contrails, the local air pressure and temperature do not change significantly; what matters instead is that the exhaust contains both water vapor (which increases the local water-vapor
concentration In chemistry, concentration is the abundance of a constituent divided by the total volume of a mixture. Several types of mathematical description can be distinguished: '' mass concentration'', ''molar concentration'', ''number concentration'', an ...
and so its partial pressure, resulting in elevated dew point and freezing point) as well as
aerosol An aerosol is a suspension (chemistry), suspension of fine solid particles or liquid Drop (liquid), droplets in air or another gas. Aerosols can be natural or Human impact on the environment, anthropogenic. Examples of natural aerosols are fog o ...
s (which provide nucleation centers for the
condensation Condensation is the change of the state of matter from the gas phase into the liquid phase, and is the reverse of vaporization. The word most often refers to the water cycle. It can also be defined as the change in the state of water vapor to ...
and freezing).


Formation flight

One theory on migrating bird flight states that many larger bird species fly in a
V formation A V formation is the symmetric V-shaped flight formation of flights of geese, swans, ducks, and other migratory birds, improving their energy efficiency. Usually, large birds fly in this formation since smaller birds create more complex wind c ...
so that all but the leader bird can take advantage of the
upwash In aeronautics, downwash is the change in direction of air deflected by the aerodynamic action of an airfoil, wing, or helicopter rotor blade in motion, as part of the process of producing lift.Crane, Dale: ''Dictionary of Aeronautical Terms, th ...
part of the wingtip vortex of the bird ahead.


Hazards

Wingtip vortices can pose a hazard to aircraft, especially during the
landing Landing is the last part of a flight, where a flying animal, aircraft, or spacecraft returns to the ground. When the flying object returns to water, the process is called alighting, although it is commonly called "landing", "touchdown" or ...
and
takeoff Takeoff is the phase of flight in which an aerospace vehicle leaves the ground and becomes airborne. For aircraft traveling vertically, this is known as liftoff. For aircraft that take off horizontally, this usually involves starting with a t ...
phases of flight. The intensity or strength of the vortex is a function of aircraft size, speed, and configuration (flap setting, etc.). The strongest vortices are produced by heavy aircraft, flying slowly, with wing flaps and landing gear retracted ("heavy, slow and clean"). Large
jet aircraft A jet aircraft (or simply jet) is an aircraft (nearly always a fixed-wing aircraft) propelled by jet engines. Whereas the engines in propeller-powered aircraft generally achieve their maximum efficiency at much lower speeds and altitudes, je ...
can generate vortices that can persist for many minutes, drifting with the wind. The hazardous aspects of wingtip vortices are most often discussed in the context of
wake turbulence Wake turbulence is a disturbance in the atmosphere that forms behind an aircraft as it passes through the air. It includes variety of elements, the most significant of which are wingtip vortices and jetwash. Jetwash refers to the rapidly moving g ...
. If a light aircraft immediately follows a heavy aircraft, wake turbulence from the heavy aircraft can roll the light aircraft faster than can be resisted by use of ailerons. At low altitudes, in particular during takeoff and landing, this can lead to an upset from which recovery is not possible. ("Light" and "heavy" are relative terms, and even smaller jets have been rolled by this effect.)
Air traffic controller Air traffic control specialists, abbreviated ATCS, are personnel responsible for the safe, orderly, and expeditious flow of air traffic in the global air traffic control system. Usually stationed in air traffic control centers and control ...
s attempt to ensure an adequate separation between departing and arriving aircraft by issuing wake turbulence warnings to pilots. In general, to avoid vortices an aircraft is safer if its takeoff is before the rotation point of the airplane that took off before it. However care must be taken to stay upwind (or otherwise away) from any vortices that were generated by the previous aircraft. On landing behind an airplane the aircraft should stay above the earlier one's flight path and touch down further along the runway.
Glider Glider may refer to: Aircraft and transport Aircraft * Glider (aircraft), heavier-than-air aircraft primarily intended for unpowered flight ** Glider (sailplane), a rigid-winged glider aircraft with an undercarriage, used in the sport of glidin ...
pilots routinely practice flying in wingtip vortices when they do a maneuver called "boxing the wake". This involves descending from the higher to lower position behind a tow plane. This is followed by making a rectangular figure by holding the glider at high and low points away from the towing plane before coming back up through the vortices. (For safety this is not done below 1500 feet above the ground, and usually with an instructor present.) Given the relatively slow speeds and lightness of both aircraft the procedure is safe but does instill a sense of how strong and where the turbulence is located.Boxing the Wake
/ref>


Gallery

Image:EA-6B Prowler from VAQ-138.jpg, An
EA-6 Prowler The Northrop Grumman (formerly Grumman) EA-6B Prowler is a twin-engine, four-seat, mid-wing electronic-warfare aircraft derived from the A-6 Intruder airframe. The EA-6A was the initial electronic warfare version of the A-6 used by the United ...
with condensation in the cores of its wingtip vortices and also on the top of its wings. Image:DehavillandCC-115Buffalo12.JPG, Vortices can be formed at the ends of propeller blades, as seen on this
DHC-5 Buffalo The de Havilland Canada DHC-5 Buffalo is a short takeoff and landing (STOL) utility transport turboprop aircraft developed from the earlier piston-powered DHC-4 Caribou. The aircraft has extraordinary STOL performance and is able to take off ...
. Image:Wingtip condensation.jpg, The core of the vortex trailing from the tip of the
flap Flap may refer to: Arts, entertainment, and media * ''Flap'' (film), a 1970 American film * Flap, a boss character in the arcade game ''Gaiapolis'' * Flap, a minor character in the film '' Little Nemo: Adventures in Slumberland'' Biology and he ...
of a commercial airplane with landing flap extended. Image:Cessna 182 model-wingtip-vortex.jpg, Wingtip vortices from a Cessna 182
wind tunnel Wind tunnels are large tubes with air blowing through them which are used to replicate the interaction between air and an object flying through the air or moving along the ground. Researchers use wind tunnels to learn more about how an aircraft ...
model. Image:C17-Vortex.JPG, Wingtip vortices shown in
flare A flare, also sometimes called a fusée, fusee, or bengala in some Latin-speaking countries, is a type of pyrotechnic that produces a bright light or intense heat without an explosion. Flares are used for distress signaling, illumination, ...
smoke left behind a
C-17 Globemaster III The McDonnell Douglas/Boeing C-17 Globemaster III is a large military transport aircraft that was developed for the United States Air Force (USAF) from the 1980s to the early 1990s by McDonnell Douglas. The C-17 carries forward the name of two ...
. Also known as smoke angels. file:MV-22B Osprey (USMC) 008.jpg, The
MV-22 Osprey The Bell Boeing V-22 Osprey is an American multi-mission, tiltrotor military aircraft with both vertical takeoff and landing (VTOL) and short takeoff and landing (STOL) capabilities. It is designed to combine the functionality of a convention ...
tiltrotor A tiltrotor is an aircraft which generates lift and propulsion by way of one or more powered rotors (sometimes called ''proprotors'') mounted on rotating shafts or nacelles usually at the ends of a fixed wing. Almost all tiltrotors use a trans ...
has a high
disk loading In fluid dynamics, disk loading or disc loading is the average pressure change across an actuator disk, such as an airscrew. Airscrews with a relatively low disk loading are typically called rotors, including helicopter main rotors and tail rot ...
, producing visible blade tip vortices. File:Euler tip vortex.png, Euler computation of a steady tip vortex. Contour colours and isosurface reveal vorticity. File:Model in Vortex Facility - GPN-2000-001288.jpg, A
Boeing 747 The Boeing 747 is a large, long-range wide-body airliner designed and manufactured by Boeing Commercial Airplanes in the United States between 1968 and 2022. After introducing the 707 in October 1958, Pan Am wanted a jet times its size, t ...
model has just passed through a stationary sheet of smoke, which is showing its trailing vortices, at the Vortex Facility at the Langley Research Center.


See also

*
Aspect ratio (wing) In aeronautics, the aspect ratio of a wing is the ratio of its span to its mean chord. It is equal to the square of the wingspan divided by the wing area. Thus, a long, narrow wing has a high aspect ratio, whereas a short, wide wing has a low a ...
*
Contrail Contrails (; short for "condensation trails") or vapor trails are line-shaped clouds produced by aircraft engine exhaust or changes in air pressure, typically at aircraft cruising altitudes several miles above the Earth's surface. Contrails ar ...
*
Helmholtz's theorems In fluid mechanics, Helmholtz's theorems, named after Hermann von Helmholtz, describe the three-dimensional motion of fluid in the vicinity of vortex lines. These theorems apply to inviscid flows and flows where the influence of viscous forces are ...
*
Horseshoe vortex The horseshoe vortex model is a simplified representation of the vortex system present in the flow of air around a wing. This vortex system is modelled by the ''bound vortex'' (bound to the wing) and two '' trailing vortices'', therefore having ...
*
Lift-induced drag In aerodynamics, lift-induced drag, induced drag, vortex drag, or sometimes drag due to lift, is an aerodynamic drag force that occurs whenever a moving object redirects the airflow coming at it. This drag force occurs in airplanes due to wings or ...
*
V formation A V formation is the symmetric V-shaped flight formation of flights of geese, swans, ducks, and other migratory birds, improving their energy efficiency. Usually, large birds fly in this formation since smaller birds create more complex wind c ...
*
Vortex In fluid dynamics, a vortex ( : vortices or vortexes) is a region in a fluid in which the flow revolves around an axis line, which may be straight or curved. Vortices form in stirred fluids, and may be observed in smoke rings, whirlpools in th ...
*
Wake turbulence Wake turbulence is a disturbance in the atmosphere that forms behind an aircraft as it passes through the air. It includes variety of elements, the most significant of which are wingtip vortices and jetwash. Jetwash refers to the rapidly moving g ...
* Crow instability


References

*Clancy, L.J. (1975), ''Aerodynamics'', Pitman Publishing Limited, London


Notes


External links

*Video from
NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeeding t ...
's
Dryden Flight Research Center The NASA Neil A. Armstrong Flight Research Center (AFRC) is an aeronautical research center operated by NASA. Its primary campus is located inside Edwards Air Force Base in California and is considered NASA's premier site for aeronautical rese ...
tests on wingtip vortices: **
C-5 Galaxy The Lockheed C-5 Galaxy is a large military transport aircraft designed and built by Lockheed, and now maintained and upgraded by its successor, Lockheed Martin. It provides the United States Air Force (USAF) with a heavy intercontinental-rang ...


**
Lockheed L-1011 The Lockheed L-1011 TriStar, also known as the L-1011 (pronounced "El-ten-eleven") and TriStar, is an American medium-to-long-range, wide-body trijet airliner built by the Lockheed Corporation. It was the third wide-body airliner to enter comme ...

Wingtip Vortices during a landing - Video at Youtube
{{DEFAULTSORT:Wingtip Vortices Aviation risks Aerodynamics Vortices Aircraft wing design Articles containing video clips ja:ウェーク・タービュランス