Balloon is a bag or envelope filled with heated air or a light gas, causing it to rise and float in the air. Air consists of a mixture of gases, mainly nitrogen and oxygen. Certain gases are lighter than others. In addition, a gas that is hot is lighter than the same gas when it is cool. A balloon rises because the heated air or gas inside is lighter than the surrounding air.
Balloons come in many sizes, shapes, and designs and have many uses. Children play with toy balloons. Scientists gather information about the weather using balloons that carry instruments up into the sky. Balloons can also carry equipment for relaying radio and television signals to remote areas. Some balloons have a basket attached beneath the bag to carry a pilot and passengers. Such large, piloted balloons are used in sport ballooning. Piloted balloons are also used for scientific research.
Balloons may be captive, free-floating, or powered. A captive balloon is anchored to the ground by a cable. A free-floating balloon drifts in whatever direction the wind blows. In a piloted free-floating balloon, the pilot can control the vertical movement of the balloon. The pilot cannot steer the balloon but can control its course somewhat by rising or descending to winds blowing in different directions.
Loading the player...Hot-air balloons
A powered balloon is called an airship. An airship has an engine and propellers to power its flight, along with rudders and instruments that enable a pilot to steer. This article deals primarily with free-floating balloons. For more information on airships, see Airship.
In many countries, balloon pilots must be certified or licensed by a government agency. There are often different levels of qualification, ranging from student to commercial pilot. To obtain a ballooning certificate or license, a person usually must meet minimum age requirements, have a certain number of hours of flight experience, and pass practical and written exams. Higher levels of qualification typically involve more experience and more advanced tests.
Kinds
There are two main kinds of balloons: (1) hot-air balloons and (2) gas balloons. Hot-air balloons are used mainly for sport ballooning. Gas balloons are used for sport ballooning, scientific research, and a variety of other purposes.
Hot-air balloons
rise because the air inside the bag is warmer—and therefore lighter—than the surrounding air. Air expands when heated, which makes it less dense—and thus lighter—than an equal volume of cooler air. In a hot-air balloon, the air is heated with a burner fueled by propane, a relatively safe and inexpensive flammable gas. The burner produces a flame that reaches up into the bag, heating the air inside. The bottom of the bag has a large opening, called the mouth, through which air heated by the burner rises into the bag.
The bag of a hot-air balloon is made of nylon or polyester. The size of the bag depends on the weight of the payload that the bag has to lift. The payload includes the passengers and any supplies beyond those necessary to maintain the balloon’s flight. The heavier the payload is, the larger the bag must be. The size of the balloon is normally expressed in terms of the volume of the bag when fully inflated. To carry two passengers and a pilot, the bag generally must have a volume of about 65,000 to 75,000 cubic feet (1,840 to 2,100 cubic meters).
The payload of a hot-air balloon sits in the basket, which hangs from strong tapes sewn into the bag. The basket is made of wicker or aluminum. The burner stands on a metal platform above the basket and directly below the bag’s mouth. Fuel hoses carry propane to the burner from tanks in the basket.
Gas balloons
may be inflated with hydrogen, helium, natural gas, or any other gas that is lighter than air. Hydrogen is the lightest of all gases and so has the greatest lifting power. But hydrogen must be handled with care because it is highly explosive. Although helium is slightly heavier than hydrogen, it is much safer. Natural gas produces less lift than either hydrogen or helium but costs far less.
The most important kinds of gas balloons include (1) sport balloons, (2) expandable balloons, (3) superpressure balloons, and (4) zero-pressure balloons. The last three kinds are used for scientific purposes. Some can carry instruments that record atmospheric data up to altitudes of over 30 miles (48 kilometers).
Sport balloons.
The bag of a gas sport balloon may be made of plastic or rubberized cotton. A popular type of gas sport balloon, inflated to carry six people, has a volume of about 35,000 cubic feet (1,000 cubic meters). A balloon of this size has a diameter of about 40 feet (12 meters).
The bag is inflated through an open tube at the bottom. This tube, called the appendix, remains open during flight. Air pressure—the amount of force with which the air pushes against the balloon and other objects—decreases with altitude. Thus, as the balloon rises into the sky, the air squeezes the balloon less and less, allowing the gas in the bag to expand. The excess gas escapes automatically through the appendix.
At the top of the bag is another opening, covered by a valve. The valve is connected to a rope that hangs down through the bag, out the appendix, and into the basket. To make the balloon descend, the pilot pulls on the rope, opening the valve to let out small amounts of gas.
Sounding balloons
consist of a closed rubber bag that is inflated before take-off. As the balloon rises, the gas inside expands, stretching the bag. A sounding balloon measuring 5 feet (1.5 meters) in diameter at take-off can stretch more than 20 feet. When the balloon reaches a certain height, the bag stretches so much that it bursts. A parachute then opens, carrying the bag’s payload of instruments to the ground.
Sounding balloons are widely used by meteorologists (scientists who study the weather). These balloons often carry a device called a radiosonde. A radiosonde has instruments that measure the temperature, humidity, and pressure of the air at various altitudes. It also includes a radio, which sends the readings to stations on the ground. Meteorologists use this information in forecasting the weather.
Superpressure balloons
balance the pressure inside the balloon bag with the air pressure to maintain a constant altitude. At launch, superpressure balloons are partially inflated and then sealed off. As the balloon ascends, the lifting gas expands to fill the envelope, pushing out against the envelope with a growing pressure. The envelope must be strong enough to withstand this pressure or it will burst, much like the envelope of a sounding balloon.
At a certain altitude, the weight of the balloon and its payload matches the weight of the air it displaces. The balloon then floats at this altitude without moving up or down. After sunset, the balloon’s gas cools in the colder night air. Ordinarily, cool gas has less lifting power than warm gas. But because the balloon is sealed, it still displaces the same weight of air, so it continues to float at the same altitude, day or night.
Superpressure balloons come in many sizes. The size determines the altitude at which the balloon will float. The larger the balloon, the higher it will rise. The largest balloons have volumes of millions of cubic feet (hundreds of thousands of cubic meters) and can rise to altitudes over 20 miles (32 kilometers) high.
A superpressure balloon can remain aloft for many months as it circles Earth. Operators on the ground or aboard aircraft control the balloon’s equipment by radio. To make the balloon descend, the operators send a signal that causes the bag to deflate.
Scientists use superpressure balloons to carry instruments for observing conditions in the atmosphere, such as radiation levels and wind movements. Because the balloons can float at high altitudes, instruments they carry can get a clearer picture of stars and planets than instruments on the ground can. The high altitudes minimize blurring due to the atmosphere.
Zero-pressure balloons
are not sealed. The bag is usually made of a plastic called polyethylene. It is partly inflated at take-off through an opening called a duct. As the balloon reaches higher altitudes, the gas expands to fill out the envelope. After sunset, as the balloon cools, excess gas escapes through the duct.
As gas escapes, the balloon loses lifting power. From time to time, the balloon must release ballast (weight) to make up for the lost gas and remain aloft. The ballast typically consists of sand grains or steel grit, a finely powdered form of steel. Operators on the ground control the release of ballast through radio signals. When the ballast is gone, the balloon eventually loses enough gas to descend to the ground. The flight of a zero-pressure balloon generally lasts no more than a few weeks.
Zero-pressure balloons come in many sizes. Some are as large as 600 feet (180 meters) in diameter.
Zero-pressure balloons once carried scientific researchers to conduct investigations of the upper atmosphere. People cannot survive in the low pressure of the upper atmosphere. Therefore, the researchers either wore pressure suits or rode in airtight, pressurized cabins. Information obtained using zero-pressure and superpressure balloons has aided scientists in developing space programs.
Operation
Scientific balloons are generally operated remotely by people on the ground. But other kinds of balloons are piloted by people onboard.
Operation of a hot-air balloon.
To inflate a hot-air balloon, the pilot spreads out the bag on the ground, with the top of the bag lying downwind from the basket. The pilot then lays the basket on its side and attaches it to the bottom of the bag. A large fan blows air into the mouth of the bag. When the bag is about three-fourths inflated, the pilot starts the burner. As the air heats, the bag gradually rises, pulls the basket upright, and floats up over the burner and the basket. To lift off, the pilot continues feeding fuel to the burner.
A hot-air balloon does not carry ballast. To ascend, the pilot burns more fuel. To descend, the pilot burns less fuel.
Older balloons have a vertical slit on top called the cooling vent. The vent is operated by pulling a cord. Pilots use the cooling vent to rapidly cool the air inside the balloon, causing a quick descent. Next to the cooling vent, older balloons typically have a rip panel, which is also operated by pulling a cord. When landing, pilots open the rip panel a second or two before the basket touches the ground to rapidly deflate the bag. If the bag is not deflated upon landing, the wind can catch it and drag the basket around the ground.
Most new balloons combine the cooling vent and the rip panel in a parachute top. This device looks like a parachute plugging an opening at the top of the bag.
Operation of a gas balloon.
To begin, a pilot spreads out the gas balloon’s bag so that its top is centered over its bottom and the rest of the fabric is laid out evenly. The pilot installs the valve at the top of the bag and then begins inflating the bag.
Some new sport gas balloons are inflated quickly, much as hot-air balloons are. Other gas balloons have a cotton net with wide meshes (open spaces) covering the bag. The pilot attaches the net before inflation. As the bag fills, sandbags are hooked in the net to hold the balloon in place. The sandbags are moved down mesh by mesh to let the balloon up slowly. The net’s bottom is eventually attached to a wooden or metal structure called the load ring, which carries the basket. The pilot hangs the sandbags along the sides of the basket, where they will serve as ballast.
Gas balloon pilots control the balloon’s altitude using ballast, generally in the form of sandbags. To lift off, the pilot removes a few sandbags until the balloon is just light enough to rise smoothly and clear any obstacles downwind. Once the balloon is aloft, the pilot drops small amounts of sand to ascend farther. To lose altitude, the pilot opens the valve at the top of the bag and lets out some gas.
Most gas balloons carry a heavy drag rope, which is thrown out just before landing to lighten the load and cushion the fall. A person on the ground can also grab the rope to get control of the balloon. As the basket touches ground, the pilot opens a rip panel to deflate the bag so the wind will not drag the basket.
Sport ballooning
Gas and hot-air balloons are both used for sport ballooning. Many balloonists participate in races and rallies. Others simply enjoy drifting peacefully over the landscape. World championships for hot-air balloons and gas balloons are held in alternate years in various countries.
In the United States, almost all sport balloonists use hot-air balloons. The United States National Hot-Air Balloon Championships, begun in 1963, take place annually.
Most sport balloon flights take place early in the morning or late in the afternoon, when the wind is usually less strong. Sport balloons are relatively simple to operate, but a pilot must pay close attention to weather conditions.
Captive balloons
Captive balloons, which are anchored to the ground, have a number of uses in business and industry. Some businesses use captive balloons in outdoor displays. These balloons are often shaped like cartoon characters.
Captive balloons are sometimes used to relay radio and television signals to remote areas. These balloons are sausage-shaped and have a fin assembly on one end, which helps hold them steady in the wind. Operators at ground control stations monitor the broadcasting equipment, as well as the altitude and internal pressure of the balloons.
History
The Chinese used small hot-air balloons to pass visual signals between military units during the 200’s A.D. Balloons were not developed in Europe until many centuries later.
Hot-air balloons in Europe.
In the late 1700’s, two French papermakers, the brothers Jacques Étienne and Joseph Michel Montgolfier, began experimenting with hot-air balloons. The Montgolfiers started their experiments by filling small paper bags with smoke. They at first thought the smoke made the bags ascend. But they later learned that hot air caused the bags to rise.
A French scientist named Jean François Pilâtre de Rozier and an army officer, François Laurent, Marquis d’Arlandes, made the first free flight in a balloon built by the Montgolfiers on Nov. 21, 1783. The two men traveled about 5 miles (8 kilometers) and stayed up about 25 minutes, drifting over Paris.
The hydrogen balloon.
Also during this time, a French chemist named Jacques Alexandre Charles was working on hydrogen balloons. Charles was assisted by two craftsmen, the brothers Anne-Jean and Nicolas Robert. Charles and the Robert brothers launched the first hydrogen balloon in Paris on Aug. 27, 1783. The balloon, which carried no passengers, was made of rubberized silk.
Jacques Charles and Nicolas Robert made the first flight in a hydrogen balloon on Dec. 1, 1783. They took off in Paris, rose about 2,000 feet (600 meters), and drifted more than 25 miles (40 kilometers) from the city. As the men landed, Charles decided to re-ascend. Robert stepped out of the basket and the balloon, relieved of Robert’s weight but still carrying Charles, quickly rose 9,000 feet (2,700 meters). He landed safely but never flew again. The basic design of his hydrogen balloon is still used in the traditional sport balloon.
The growth of ballooning.
By the late 1700’s, ballooning had become a popular trend in Europe, especially in France. Balloon ascents drew many spectators, and balloonists became local heroes. Most of the ascents were made in gas balloons.
On Jan. 7, 1785, Jean-Pierre Blanchard, a French balloonist, and an American doctor named John Jeffries made the first balloon flight across the English Channel. They took off from Dover, England, and landed near Calais, France, two and a half hours later. In 1793, Blanchard also made the first balloon voyage in the United States. The balloon ascent took place in Philadelphia before a large crowd that included President George Washington. Blanchard landed in Gloucester County, New Jersey. His wife, Madeleine-Sophie, also was a famous balloonist.
Balloons in war.
France first used balloons in warfare in 1794. France was then at war with several other European countries. The French used captive balloons as observation platforms to learn the locations of enemy troops and direct the movements of French troops.
During the American Civil War (1861-1865), a balloonist named Thaddeus Lowe organized and directed a balloon corps in the Union Army. The North used captive observation balloons to direct artillery fire and to report Confederate troop movements.
Balloons had another use during the Franco-Prussian War (1870-1871), when German armies surrounded Paris. The people of Paris communicated with the outside world by means of balloons and carrier pigeons. They launched more than 60 balloons, which carried more than 2 million pieces of mail.
During World War I (1914-1918), captive observation balloons were widely used both by the Allies, which included France, the United Kingdom, and Italy, and by the Central Powers, which included Germany and Austria-Hungary. The United Kingdom also introduced balloon barrages during the war for protection against low-flying enemy airplanes. The barrages consisted of groups of captive balloons from which steel cables were suspended. Enemy planes had to fly above the balloons or risk being ripped apart by the cables. The British set up a barrage 51 miles (82 kilometers) long around London. Italy, France, and Germany also used balloon barrages.
During World War II (1939-1945), balloon barrages were again used by the United Kingdom and other Allied nations and by Germany and other Axis countries. The barrages were used on land and on ships. The Japanese used balloons to carry bombs. They released more than 9,000 bomb-carrying balloons that were intended to land on the West Coast of the United States. Only a few hundred are known to have reached the United States, and the damage was mostly minor.
In the 2000’s and 2010’s, the United States launched balloons over areas in Iraq and Afghanistan. The balloons carried remote-controlled cameras for monitoring the activities of insurgents on the ground.
Balloon explorations
of the upper atmosphere reached new heights in the early 1930’s. Auguste Piccard, a Swiss physicist, invented an airtight cabin, which he attached to a huge hydrogen balloon. In 1931, he and an assistant, Paul Kipfer, ascended in the balloon from Augsburg, Germany. They rose nearly 52,000 feet (15,850 meters) into the stratosphere, the atmospheric layer above nearly all clouds. During this flight and an even higher flight made in 1932, Piccard studied cosmic rays, high-energy particles that originate in space.
On Aug. 16, 1960, U.S. Air Force Captain Joseph W. Kittinger, Jr., ascended to a new record height of 102,800 feet (31,333 meters). Instead of remaining with the balloon for the descent back to the ground, Kittinger jumped out wearing a special parachute. He fell for 4 minutes 36 seconds before the parachute opened. In 2012, the Austrian daredevil and former paratrooper Felix Baumgartner broke the altitude record and also became the first person to skydive faster than the speed of sound. After ascending 128,100 feet (39,045 meters) in a helium balloon, Baumgartner plunged through the upper atmosphere at 833.9 miles (1,342 kilometers) per hour. Kittinger served as part of Baumgartner’s mission control on the ground. In 2014, American skydiver Alan Eustace broke Baumgartner’s altitude record when he jumped out of a balloon about 135,900 feet (41,420 meters) over New Mexico.
Long-distance balloon flights.
In 1978, three American balloonists—Ben Abruzzo, Maxie Anderson, and Larry Newman—made the first crossing of the Atlantic Ocean in a balloon. Their helium balloon lifted off from Presque Isle, Maine, and landed about 60 miles (95 kilometers) northwest of Paris. Joe Kittinger made the first solo crossing of the Atlantic in 1984.
In 1999, two balloonists became the first to fly around the world without landing. They were Bertrand Piccard, a Swiss psychiatrist and the grandson of Auguste Piccard, and Brian Jones, a British pilot. Their craft was a hybrid balloon with separate compartments containing helium and hot air. The helium provided most of the lift, but hot air helped control altitude. A thin layer of foam insulation surrounded the helium compartment. It helped prevent the helium from expanding and leaking out during the day and from contracting at night. This feature helped conserve fuel that the balloonists would otherwise have had to burn to keep the balloon aloft.
Piccard and Jones lifted off from Château-d’Oex in the Swiss Alps and landed about 300 miles (480 kilometers) southwest of Cairo, Egypt. Their balloon circled the planet, then continued on, setting official world records for distance and duration of flight. The balloon traveled 25,361 miles (40,814 kilometers) in 19 days 21 hours 47 minutes.
In 2002, Steve Fossett of the United States succeeded in his sixth attempt to become the first person to complete a solo balloon flight around the world. Fossett’s balloon took off from Northam, Western Australia, and landed near Windorah, Queensland, Australia. It traveled an official distance of 20,626 miles (33,195 kilometers). The balloon completed its circle around Earth in 13 days 8 hours 33 minutes. Fossett’s flight also set a new record for flight duration by a solo balloonist—14 days 19 hours 50 minutes.
