Aerostat
Overview
 
An aerostat (From Greek
Greek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...

 ἀήρ aer (air) + στατός statos (standing) through French) is a craft that remains aloft primarily through the use of buoyant
Buoyancy
In physics, buoyancy is a force exerted by a fluid that opposes an object's weight. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus a column of fluid, or an object submerged in the fluid, experiences greater pressure at the bottom of the...

 lighter than air
Lighter than air
Lighter than air refers to gases that are buoyant in air because they have densities lower than that of air .Some of these gases are used as lifting gases in lighter-than-air aircraft, which include free balloons, moored balloons, and airships, to make the whole craft, on average, lighter than air...

 gases, which impart lift to a vehicle with nearly the same overall density as air. Aerostats include free balloons
Balloon (aircraft)
A balloon is a type of aircraft that remains aloft due to its buoyancy. A balloon travels by moving with the wind. It is distinct from an airship, which is a buoyant aircraft that can be propelled through the air in a controlled manner....

, airship
Airship
An airship or dirigible is a type of aerostat or "lighter-than-air aircraft" that can be steered and propelled through the air using rudders and propellers or other thrust mechanisms...

s, and moored balloon
Moored balloon
A moored balloon is an inflated fabric structure, often shaped like an airship and usually filled with helium, that is restrained by a cable attached to the ground or a vehicle. Moored balloons differ from airships and free balloons in that it is not free-flying.Moored balloons are sometimes...

s. An aerostat's main structural component is its envelope, a lightweight skin
Skin
-Dermis:The dermis is the layer of skin beneath the epidermis that consists of connective tissue and cushions the body from stress and strain. The dermis is tightly connected to the epidermis by a basement membrane. It also harbors many Mechanoreceptors that provide the sense of touch and heat...

 containing a lifting gas
Lifting gas
Because of the Archimedes' principle, a lifting gas is required for aerostats to create buoyancy. Its density is lower than that of air . Only certain lighter than air gases are suitable as lifting gases.- Hot Air :...

 to provide buoyancy
Buoyancy
In physics, buoyancy is a force exerted by a fluid that opposes an object's weight. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus a column of fluid, or an object submerged in the fluid, experiences greater pressure at the bottom of the...

, to which other components are attached.
Encyclopedia
An aerostat (From Greek
Greek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...

 ἀήρ aer (air) + στατός statos (standing) through French) is a craft that remains aloft primarily through the use of buoyant
Buoyancy
In physics, buoyancy is a force exerted by a fluid that opposes an object's weight. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus a column of fluid, or an object submerged in the fluid, experiences greater pressure at the bottom of the...

 lighter than air
Lighter than air
Lighter than air refers to gases that are buoyant in air because they have densities lower than that of air .Some of these gases are used as lifting gases in lighter-than-air aircraft, which include free balloons, moored balloons, and airships, to make the whole craft, on average, lighter than air...

 gases, which impart lift to a vehicle with nearly the same overall density as air. Aerostats include free balloons
Balloon (aircraft)
A balloon is a type of aircraft that remains aloft due to its buoyancy. A balloon travels by moving with the wind. It is distinct from an airship, which is a buoyant aircraft that can be propelled through the air in a controlled manner....

, airship
Airship
An airship or dirigible is a type of aerostat or "lighter-than-air aircraft" that can be steered and propelled through the air using rudders and propellers or other thrust mechanisms...

s, and moored balloon
Moored balloon
A moored balloon is an inflated fabric structure, often shaped like an airship and usually filled with helium, that is restrained by a cable attached to the ground or a vehicle. Moored balloons differ from airships and free balloons in that it is not free-flying.Moored balloons are sometimes...

s. An aerostat's main structural component is its envelope, a lightweight skin
Skin
-Dermis:The dermis is the layer of skin beneath the epidermis that consists of connective tissue and cushions the body from stress and strain. The dermis is tightly connected to the epidermis by a basement membrane. It also harbors many Mechanoreceptors that provide the sense of touch and heat...

 containing a lifting gas
Lifting gas
Because of the Archimedes' principle, a lifting gas is required for aerostats to create buoyancy. Its density is lower than that of air . Only certain lighter than air gases are suitable as lifting gases.- Hot Air :...

 to provide buoyancy
Buoyancy
In physics, buoyancy is a force exerted by a fluid that opposes an object's weight. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus a column of fluid, or an object submerged in the fluid, experiences greater pressure at the bottom of the...

, to which other components are attached. One of the most recent deployments of an aerostat was seen at the opening ceremony of the nineteenth 2010 Commonwealth Games
2010 Commonwealth Games
The 2010 Commonwealth Games, officially known as the XIX Commonwealth Games, were held in Delhi, India, from 3 to 14 October 2010. A total of 6,081 athletes from 71 Commonwealth nations and dependencies competed in 21 sports and 272 events, making it the largest Commonwealth Games till date...

, held in Delhi, India. The aerostat used in the ceremony was the largest in the world.

Aerostats are so named because they use "aerostatic" lift which is a buoyant force that does not require movement through the surrounding air mass. This contrasts with aerodyne
Aerodyne
Aerodyne may refer to:*Heavier-than-air aircraft, deriving lift from dynamic motion through the air.*The Fender Aerodyne Telecaster, a contemporary model of the classic Fender Telecaster Electric guitar....

s that primarily use aerodynamic lift
Lift (force)
A fluid flowing past the surface of a body exerts a surface 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 surface force parallel to the flow direction...

 which requires the movement of at least some part of the aircraft
Aircraft
An aircraft is a vehicle that is able to fly by gaining support from the air, or, in general, the atmosphere of a planet. An aircraft counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines.Although...

 through the surrounding air mass.

Terminology

There are two distinct senses for the scope of term aerostat. In the broader sense, the term refers to all systems that remain aloft primarily using aerostatic buoyancy. In the narrower sense, the term is used to refer to the most common type of aerostat which is the moored balloon
Moored balloon
A moored balloon is an inflated fabric structure, often shaped like an airship and usually filled with helium, that is restrained by a cable attached to the ground or a vehicle. Moored balloons differ from airships and free balloons in that it is not free-flying.Moored balloons are sometimes...

s. This article uses the term in its broader sense. For the narrower sense, see moored balloon
Moored balloon
A moored balloon is an inflated fabric structure, often shaped like an airship and usually filled with helium, that is restrained by a cable attached to the ground or a vehicle. Moored balloons differ from airships and free balloons in that it is not free-flying.Moored balloons are sometimes...

.

Moored balloons

Systems that are connected to the surface via one or more tethers. In contrast to the other types of aerostats, moored balloons are non-free flying. A notable example of moored balloons are barrage balloons. Some moored balloons obtain aerodynamic lift
Lift (force)
A fluid flowing past the surface of a body exerts a surface 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 surface force parallel to the flow direction...

 via the contours of their envelope or through the use of fins. Moored balloons are also used for sight seeing and advertising. Aerophile SA
Aerophile SA
Aerophile SA is a French company specializing in tethered helium balloons, which offer a safe aerial experience from a fixed location.- History :...

 has made the first one in 1994 and have sold so far more than 50 of them in 25 countries becoming the world's largest lighter than air carrier ever with 300 000 passengers flown every year.

Helikites

A trademarked name given to a patented combination of a helium balloon and a kite to form a single, aerodynamically sound tethered aircraft, that exploits both wind and helium for its lift. The attached balloon is generally oblate-spheroid in shape although this is not essential. A Helikite is not a moored balloon, because a Helikite is not a balloon. A Helikite is a tethered aerostat. The US Customs classifies a Helikite as "other non-powered aircraft" not as balloons. The British Civil Aviation Authority's Air Navigation Order gives Helikites its own classification as "Helikites" as opposed to "kites" and "balloons". A Helikite is not just a kite because Helikites fly in nil wind and kites need wind to fly. A Helikite is not just a balloon because Helikites can fly even if weighed down to be heavier than air whereas balloons will never fly if heavier than air. A Helikite is a new type of tethered aerostat with its own official classification. Trials have shown that Helikites fly to greater altitudes than tethered balloons and in far higher winds. They stay stationary and steady in the air in more conditions and for longer than any other type of aerostat. If the word aerostat comes from the greek "aer" + "statos" then Helikites are a pure form of aerostat.

Free balloons

Free-flying buoyant aircraft
Aircraft
An aircraft is a vehicle that is able to fly by gaining support from the air, or, in general, the atmosphere of a planet. An aircraft counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines.Although...

 that move by being carried along by the wind. Types of free balloons include hot air balloon
Hot air balloon
The hot air balloon is the oldest successful human-carrying flight technology. It is in a class of aircraft known as balloon aircraft. On November 21, 1783, in Paris, France, the first untethered manned flight was made by Jean-François Pilâtre de Rozier and François Laurent d'Arlandes in a hot air...

s and gas balloon
Gas balloon
A gas balloon is any balloon that stays aloft due to being filled with a gas less dense than air or lighter than air . A gas balloon may also be called a Charlière for its inventor, the Frenchman Jacques Charles. Today, familiar gas balloons include large blimps and small rubber party balloons...

s.

Airships

Free-flying buoyant aircraft
Aircraft
An aircraft is a vehicle that is able to fly by gaining support from the air, or, in general, the atmosphere of a planet. An aircraft counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines.Although...

 that can be propelled and steered. Some airships obtain aerodynamic lift
Lift (force)
A fluid flowing past the surface of a body exerts a surface 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 surface force parallel to the flow direction...

  via the shape of their envelope or through the addition of fins or other shape. These types of craft are called hybrid airship
Hybrid airship
"A hybrid airship is an aircraft that combines characteristics of heavier-than-air technology, fixed-wing aircraft or helicopter, and lighter-than-air , aerostat technology."[1]Examples include helicopter/airship hybrids intended for heavy lift applications and dynamic lift airships intended for...

s.

See also

  • Aerodyne
  • Aerostatics
    Aerostatics
    Aerostatics is the study of gases that are not in motion. The corresponding study of gases in motion is called aerodynamics. It is a subfield of fluid statics.Aerostatics studies density allocation, especially in air...

  • Airship
    Airship
    An airship or dirigible is a type of aerostat or "lighter-than-air aircraft" that can be steered and propelled through the air using rudders and propellers or other thrust mechanisms...

  • Balloon (aircraft)
    Balloon (aircraft)
    A balloon is a type of aircraft that remains aloft due to its buoyancy. A balloon travels by moving with the wind. It is distinct from an airship, which is a buoyant aircraft that can be propelled through the air in a controlled manner....

  • Buoyancy
    Buoyancy
    In physics, buoyancy is a force exerted by a fluid that opposes an object's weight. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus a column of fluid, or an object submerged in the fluid, experiences greater pressure at the bottom of the...

  • Cloud nine
    Cloud nine (Tensegrity sphere)
    Cloud nine is the name Buckminster Fuller gave to his proposed airborne habitats created from giant geodesic spheres, which might be made to levitate by slightly heating the air inside above the ambient temperature....

  • Helikite
    Helikite
    The names Helikite and Helikites, are Allsopp's Registered Trade Marks relating to a new type of kite-style aerostat designed and patented by Sandy Allsopp in England....

  • Lighter than air
    Lighter than air
    Lighter than air refers to gases that are buoyant in air because they have densities lower than that of air .Some of these gases are used as lifting gases in lighter-than-air aircraft, which include free balloons, moored balloons, and airships, to make the whole craft, on average, lighter than air...

  • Metaplane
  • Moored balloon
    Moored balloon
    A moored balloon is an inflated fabric structure, often shaped like an airship and usually filled with helium, that is restrained by a cable attached to the ground or a vehicle. Moored balloons differ from airships and free balloons in that it is not free-flying.Moored balloons are sometimes...


External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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