For the impedance converter, see the article on balun.

A balloon is a flexible bag normally filled with air or gas. Some balloons are purely decorative, others are used for specific purposes. Early balloons were made of dried animal bladders. Modern balloons can be made from materials such as rubber, latex, chloroprene or a nylon fabric.

Usage of Balloons

• small balloons (volume of a few litres)
  • toy balloon
  • decoration
  • solar balloon
  • balloon mail as part of a balloon flight competition or to spread information
  • Balloon helicopter
  • Demonstration of rocket propulsion by letting the gas stream away (balloon rocket)
  • Ceiling balloon
• medium balloons (volume of hundreds to thousands of litres)
  • transport of bombs (in World War II, FUGU-Balloon)
  • transport of propaganda (in World War II and in the Cold War)
  • Ceiling balloon
  • Weather balloon used with a Radiosonde
• as fixed balloon
  • for carrying advertising signs
  • to carry antennae for LF and VLF
  • party balloon
• large balloons (volume up to 12000 cubic metres)
  • fixed balloon
    • as manned observation post (before World War II)
    • barrage balloon
    • observation balloon for military reconnaissance
    • positioning atomic bombs for bomb tests in the atmosphere
  • free flying balloons
    • lifting people, usually with a hot air balloon
    • airship actually a buoyant aircraft rather than a balloon
    • research balloon with instrumentation, also to carry telescopes
    • rockoon
    • balloon satellite for space research.
    • espionage balloon for military reconnaissance

Balloons as flying machines

Large balloons filled with hot air or buoyant gas have been used as flying machines since the 18th century. See Balloon (aircraft) and Hot air balloon

Such balloons, which lift a payload using buoyancy, should not be confused with balloons in space, launched with a rocket, which are simply large deployable structures.

Balloons are sometimes used in form of a rockoon as carrier for rockets.

Examples:

• Echo satellite
• Decoys accompanying ICBMs in midcourse, see also countermeasure

Balloons as decoration or entertainment

Party balloons are mostly made of natural latex tapped from rubber trees and can be filled with air, helium, water, or any other suitable liquid or gas. The rubber makes the volume adjustable.

Filling with air is done with the mouth or with a pump.

When rubber balloons are filled with helium so that they float (restrained by ribbons or strings) they can hold their shape for only a few hours. The enclosed air or helium escapes through small pores in the rubber. If helium is used the gas escapes quicker than in the case of air because the helium atoms are much smaller than the nitrogen and oxygen molecules in air.

Even a perfect rubber membrane eventually loses the gas to the outside, and its contents are contaminated by oxygen and nitrogen migrating inward from the outside. The gases in question actually dissolve in the rubber on one side and are released from solution on the other. The process by which a substance or solute migrates from a region of high concentration, through a barrier or membrane, to a region of lower concentration is called diffusion. The inside of balloons can be treated with a special gel (e.g. "Hi Float" brand) which coats the inside of the balloon to reduce the helium leakage, thus increasing float time. Latex rubber balloons are completely biodegradable, but cannot safely be released into the environment: they are a serious hazard to birds and wetland animals that confuse the balloons for food.

Beginning in the early 1990s, some more expensive (and longer-lasting) helium balloons have been made of thin, unstretchable, impermeable metallized nylon films. These balloons are often mistakenly called Mylar balloons. These balloons have attractive shiny reflective surfaces and are often printed with colour pictures and patterns. The most important attributes of metallized nylon for balloons are its light weight, increasing buoyancy and its ability to keep the helium gas from escaping for several weeks. However, there has been some environmental concern, since the metallized nylon does not biodegrade or shred as a rubber balloon does, and a helium balloon released into the atmosphere can travel a long way before finally bursting or deflating. Release of these types of balloons into the atmosphere is harmful to the environment.

Partygoers sometimes entertain each other by untying a balloon and inhaling the helium. Because the speed of sound in helium is about twice that in air, the helium causes the vocal tract to become more responsive to high-pitched sounds and less responsive to lower ones. The result is a voice that sounds high-pitched (and usually very funny).

Balloon artists are entertainers who twist and tie inflated tubular balloons into sculptures (see also balloon animal). The balloons used for balloon sculpture are made of extra-stretchy rubber so that they can be twisted and tied without bursting. Since the pressure required to inflate a balloon is inversely proportional to the diameter of the balloon, these tiny tubular balloons are extremely hard to inflate initially. A pump is usually used to inflate these balloons.

Decorators may use dozens of helium balloons to create balloon sculptures. Usually the round shape of the balloon restricts these to simple arches or walls, but on occasion more ambitious "sculptures" have been attempted with great success. The balloon decorating industry offers everything from simple balloon columns to stunning, very large and detailed sculptures.

Water balloons are thin, small rubber balloons intended to be easily broken. They are usually used by children, who throw them at each other, trying to get each other wet - see practical joke.

Balloons in medicine

Angioplasty is a surgical procedure in which very small balloons are inserted into blocked or partially blocked blood vessels near the heart. Once in place, the balloon can be inflated to clear or compress arterial plaque, and to stretch the walls of the vein. A small stent can be inserted in its place to keep the vessel open after the balloon's removal. See myocardial infarction.

Certain catheters have balloons at their tip to keep them from slipping out, for example the balloon of a Foley catheter is insufflated when the catheter is inserted into the urinary bladder and secures its position.

Records

Maximum flight heights

Manned Balloon

The altitude record for manned balloons is 34668 metres. It was made by Malcolm D. Ross and Victor E. Prather over the Gulf of Mexico in 1961.

Unmanned Balloon

The altitude record for unmanned balloons is (1991 edition of Guinness Book) 51.8 kilometres. The vehicle was a Winzen-Balloon with a volume of 1.35 million cubic metres, which was launched in October 1972 in Chico, California, USA. This is the greatest altitude ever reached by a flying object requiring the surrounding air. Higher altitudes can only be reached by ballistic vehicles such as rockets, rocket planes or projectiles.

Balloon tank

See Atlas (rocket).

Usage of Balloons on other planets

In 1984 the Russian space probe Vega released two aerobots into the atmosphere of Venus, from which signals were received for two days.

Balloons in movies

• The Balloonatic (1923)
• The Wizard of Oz (1939)
• Trottie True (1949)
• Globex's messy break (1954)
• Around the World in Eighty Days (1956)
• The Red Balloon (1956)
• Stowaway in the Sky (1960)
• Mysterious Island (1961)
• Five Weeks in a Balloon (1962)
• The Great Race (1965)
• Those Magnificent Men in Their Flying Machines, or How I Flew from London to Paris in 25 hours 11 minutes (1965)
• Charlie Bubbles (1967)
• Chitty Chitty Bang Bang (1968)
• The Great Bank Robbery (1969)
• The Muppet Movie (1979)
• The Chipmunk Adventure (1987)
• Batman (1989)
• Around the World in 80 Days (2004)

See also

• balloon mail
• radiosonde
• aerobot
• rockoon
• Balloon fetish
• speech balloon
• balloon animal
• balloon modelling

External links

• Work of a typical balloon artist
• Balloon art instructions and galleryde:Ballon