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{{Short description|Lighter-than-air aircraft}}
{{about|hot air balloons themselves|the activity|Hot air ballooning|other meanings|Hot air balloon (disambiguation)|and|Air balloon (disambiguation)}}
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[[File:2006 Ojiya balloon festival 011.jpg|thumb|upright=0.8|Hot air balloon in flight]]
[[File:Canberra Balloon Fiesta 2006.jpg|thumb|upright=0.8|Novelty hot air balloons resembling anthropomorphized bees]]
[[File:BallonKathedrale01 edit.jpg|thumb|Novelty hot air balloon resembling the [[Abbey of Saint Gall]]|alt=]]

A '''hot air balloon''' is a [[lighter-than-air]] aircraft consisting of a bag, called an envelope, which contains heated air. Suspended beneath is a [[Gondola (balloon)|gondola]] or [[wicker|wicker basket]] (in some long-distance or high-altitude balloons, a capsule), which carries passengers and a source of heat, in most cases an open flame caused by burning liquid [[propane]]. The heated air inside the envelope makes it [[buoyant]], since it has a [[ideal gas law|lower density]] than the colder air outside the envelope. As with all [[aircraft]], hot air balloons cannot fly beyond the [[atmosphere]]. The envelope does not have to be sealed at the bottom, since the air inside the envelope is at about the same pressure as the surrounding air. In modern sport balloons the envelope is generally made from [[nylon]] fabric, and the inlet of the balloon (closest to the burner flame) is made from a fire-resistant material such as [[Nomex]]. Modern balloons have been made in many shapes, such as rocket ships and the shapes of various commercial products, though the traditional shape is used for most non-commercial and many commercial applications.

The hot air balloon is the first successful human-carrying [[flight]] technology. The first untethered manned hot air balloon flight in the world was performed in [[Paris]], France, by [[Jean-François Pilâtre de Rozier]] and [[François Laurent d'Arlandes]] on November 21, 1783,<ref>{{cite book |title=Lighter Than Air |publisher=[[Johns Hopkins University Press]] |year=2008 |isbn=978-0-8018-9127-4 |author=Tom D. Crouch}}</ref> in a balloon created by the [[Montgolfier brothers]].<ref name="centennialofflight.gov">{{cite web |url=http://www.centennialofflight.gov/essay/Lighter_than_air/Early_Balloon_Flight_in_Europe/LTA1.htm |title=U.S. Centennial of Flight Commission: Early Balloon Flight in Europe |access-date=2008-06-04 |url-status=dead |archive-url=https://web.archive.org/web/20080602012700/http://www.centennialofflight.gov/essay/Lighter_than_air/Early_Balloon_Flight_in_Europe/LTA1.htm |archive-date=2008-06-02}}</ref> Hot air balloons that can be propelled through the air rather than simply drifting with the [[wind]] are known as [[thermal airship]]s.
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==History==
{{Main|History of ballooning}}

===Premodern and unmanned balloons===
[[File:SkyLanternRichy01.jpg|thumb|upright=0.8|A [[sky lantern]]]]

A precursor of the hot air balloon was the [[sky lantern]] ({{zh|s=孔明灯|t=孔明燈}}). [[Zhuge Liang]] of the [[Shu Han]] kingdom, during the [[Three Kingdoms]] era (220–280&nbsp;CE), used these airborne lanterns for military signaling.<ref>{{cite book |url=https://books.google.com/books?id=ssO_19TRQ9AC&q=Kongming+balloon&pg=PA112 |title=Ancient Chinese Inventions |last=Deng |first=Yinke |location=Beijing |publisher=China Intercontinental Press |year=2005|isbn=978-7508508375 }}, cited in Joel Serrão, ''Dicionário de História de Portugal'', Vol III. Porto: Livraria Figueirinhas, 1981, 184–185.</ref> The Mongolian army studied [[Kongming lantern]]s from China and used them in the [[Battle of Legnica]] during the Mongol invasion of Poland in the 13th century.<ref>Joseph Needham (1965). ''Science and Civilisation in China: Volume 4, Physics and Physical Technology, Part 2, Mechanical Engineering''; rpr. Taipei: Caves Books Ltd.</ref> This is the first time ballooning was known in the western world.

In the 18th century the Portuguese Jesuit priest [[Bartolomeu de Gusmão]] in colonial Brazil envisioned an aerial apparatus named {{lang|pt|Passarola}}, which was the predecessor of the hot air balloon. The {{lang|pt|Passarola}} was intended to serve as an air vessel in order to facilitate communication and as a strategical device.<ref>Arquivo Nacional da Torre do Tombo. "Cartas Consultas e Mais Obras de Alexandre de Gusmão" (páginas do manuscrito 201–209).</ref> In 1709 [[John V of Portugal]] decided to fund Bartolomeu de Gusmão's project following a petition made by the Jesuit priest,<ref>{{Cite web |url=http://purl.pt/706 |title=Reproduction fac-similé d'un dessin à la plume de sa description et de la pétition adressée au Jean V. (de Portugal) en langue latine et en écriture contemporaine (1709) retrouvés récemment dans les archives du Vatican du célèbre aéronef de Bartholomeu Lourenco de Gusmão "l'homme volant" portugais, né au Brésil (1685–1724) précurseur des navigateurs aériens et premier inventeur des aérostats. 1917 |last=De Gusmão |first=Bartolomeu}}</ref> and an unmanned demonstration was performed at [[Casa da Índia]] in the presence of John&nbsp;V and the queen, [[Maria Anna of Austria]], with the Italian cardinal [[Pope Innocent XIII|Michelangelo Conti]], two members of the Portuguese Royal Academy of History, one Portuguese diplomat and one chronicler serving as witnesses. This event would bring some European attention to this event and this project. A later article dated on October 20, 1786, by the London ''Daily Universal Register'' would state that the inventor was able to raise himself by the use of his prototype. Also in 1709, the Portuguese Jesuit wrote {{lang|pt|Manifesto summário para os que ignoram poderse navegar pelo elemento do ar}} (''Short Manifesto for those who are unaware that is possible to sail through the element air''); he also left designs for a manned air vessel.

In the 1970s, balloonist [[Julian Nott (balloonist)|Julian Nott]] hypothesized that the [[Nazca Lines]] [[geoglyph]]s' creation two millennia ago could have been guided by [[Nazca culture|Nazca leaders]] in a balloon, possibly the earliest hot air balloon flights in human history.<ref>{{cite web|url=http://www.nott.com/Pages/projects.php |title=Innovative Projects; The Extraordinary Nazca Prehistoric Balloon|access-date=2017-07-24|url-status=dead|archive-url=https://web.archive.org/web/20110714201319/http://www.nott.com/Pages/projects.php |archive-date=2011-07-14 }}</ref> To support this theory, in 1975 he designed and piloted the Nazca Prehistoric Balloon, claiming to have used only methods and materials available to the Pre-Inca Peruvians 1,000 years ago.<ref>{{Cite web |url=http://www.ltaflightmagazine.com/julian-nott-bizarre-accident |title=Scientist and Aviator Julian Nott Dies After a Bizarre Accident |work=LTA-Flight Magazine| date=29 March 2019 }}</ref><ref>{{cite news |last1=Browne |first1=Malcolm W. |title=Ballonist Has High Hopes But No Illusions |url=https://www.nytimes.com/1986/11/18/science/balloonist-has-high-hopes-but-no-illusions.html |newspaper=The New York Times |date=18 November 1986 |access-date=21 June 2020}}</ref>

===First manned flight===
[[File:Montgolfier Balloon.JPG|thumb|upright=0.8|A model of the Montgolfier brothers' balloon at the [[London Science Museum]]]]
The French brothers Joseph-Michel and Jacques-Étienne [[Montgolfier brothers|Montgolfier]] developed a hot-air balloon in [[Annonay]], [[Ardèche]], France, and demonstrated it publicly on September 19, 1783, making an unmanned flight lasting 10&nbsp;minutes. After experimenting with unmanned balloons and flights with animals, the first balloon flight with humans aboard, a tethered flight, performed on or around October 15, 1783, by Jean-Francois Pilatre de Rozier, who made at least one tethered flight from the yard of the Reveillon workshop in the [[Faubourg Saint-Antoine]]. Later that same day, Pilatre de Rozier became the second human to ascend into the air, reaching an altitude of {{convert|26|m|abbr=on}}, the length of the tether.<ref>{{Cite book |title=Guinness world records 2014 |last=Glenday |first=Craig |year=2013 |publisher=Guinness World Records Limited |isbn=978-1908843159 |url-access=registration |url=https://archive.org/details/guinnessworldrec0000unse_r3e7}}</ref><ref>Tom D. Crouch (2009). Lighter Than Air.</ref> The first free flight with human passengers was made a few weeks later, on November 21, 1783.<ref name="centennialofflight.gov"/> King [[Louis XVI]] had originally decreed that condemned criminals would be the first [[Aviator|pilots]], but de Rozier, along with [[François Laurent d'Arlandes|Marquis François d'Arlandes]], petitioned successfully for the honor.<ref>{{cite web |url=http://www.start-flying.com/Montgolfier.htm |title=Start-Flying: History of Balloon Flying |publisher=www.start-flying.com |access-date=2007-12-28}}</ref><ref>{{cite web |url=http://www.chm.bris.ac.uk/webprojects2003/hetherington/final/montgolfier_bros.html |title=Lighter than air: The Montgolfier Brothers | access-date=2007-12-28}}</ref><ref>{{cite web |url=http://www.nasm.si.edu/exhibitions/gal109/NEWHTF/ITM300.HTM |title=National Air and Space Museum: Pioneers of Flight gallery |access-date=2007-12-28 |archive-date=2008-04-06 |archive-url=https://web.archive.org/web/20080406191335/http://www.nasm.si.edu/exhibitions/GAL109/NEWHTF/ITM300.HTM |url-status=dead }}</ref>
The [[History of military ballooning|first military use]] of a hot air balloon happened in 1794 during the [[Battle of Fleurus (1794)|battle of Fleurus]], when the French used the balloon {{lang|fr|l'Entreprenant}} for observation.<ref>{{cite web |url=http://www.crwflags.com/fotw/flags/be-whtfl.html |title=Fleurus (Municipality, Province of Hainaut, Belgium) |publisher=CRW Flags Inc. |access-date=2010-04-21}}</ref>

===Modern balloons===
[[File:Helsinki from air.jpg|thumb|A hot air balloon over the city of [[Helsinki]] in September 2009]]
[[File:Cappadociasunrise.jpg|thumb|Hot air balloons, [[Cappadocia]] sunrise]]
[[File:Cloudhoppers.jpg|right|thumb|A pair of [[Cloudhopper|Hopper balloons]]]]
[[File:Bristol Balloon Fiesta 2009-20.JPG|right|thumb|[[Bristol International Balloon Fiesta]]]]
Modern hot air balloons, with an onboard heat source, were developed by [[Ed Yost]] and Jim Winker, beginning during the 1950s; their work resulted in his a first successful flight on October 22, 1960.<ref>{{cite news |last=Hevesi |first=Dennis |date=2007-06-04 |title=Ed Yost, 87, Father of Modern Hot-Air Ballooning, Dies |work=The New York Times |url=https://www.nytimes.com/2007/06/04/us/04yost.html?_r=1&oref=slogin |access-date=2008-06-04}}</ref> The first modern hot air balloon to be made in the United Kingdom (UK) was the [[Bristol Belle]], built in 1967. Presently, hot air balloons are used primarily for recreation.

==Records==
===Altitude===
On November 26, 2005 [[Vijaypat Singhania]] set the world altitude record for highest hot air balloon flight, reaching {{convert|21027|m|ft|abbr=on}}. He took off from downtown [[Mumbai]], India, and landed {{convert|240|km|mi|abbr=on}} south in Panchale.<ref>{{cite web |url=http://www.prdomain.com/upload/104/10443872.pdf |title=Dr. Vijaypat Singhania enters the Guinness World Records |access-date=2008-06-22 |archive-url=https://web.archive.org/web/20080624220610/http://www.prdomain.com/upload/104/10443872.pdf |archive-date=2008-06-24 |url-status=usurped }}</ref> 

The previous record of {{convert|19811|m|ft|abbr=on}} had been set by [[Per Lindstrand]] on June 6, 1988, in [[Plano, Texas]].

===Speed===
On January 15, 1991, [[Per Lindstrand]] (born in Sweden, but resident in the UK) and [[Richard Branson]] of the UK flew {{convert|7671.91|km|abbr=on}} from Japan to Northern Canada in the “Virgin Pacific Flyer”. With a volume of 74,000 cubic meters (2.6&nbsp;million cubic feet), the balloon envelope was the largest ever built for a hot air craft. Designed to fly in the trans-oceanic [[jet stream]]s, the ''[[Pacific Flyer]]'' recorded the fastest ground speed for a manned balloon at {{convert|245|mph|km/h|order=flip|abbr=on}}. 

===Length===
The longest duration record was set by Swiss psychiatrist [[Bertrand Piccard]] ([[Auguste Piccard]]'s grandson) and Briton Brian Jones, flying in the Breitling Orbiter 3. It was the first nonstop trip around the world by balloon. The balloon left Château-d'Oex, Switzerland, on March 1, 1999, and landed at 1:02&nbsp;a.m. on March 21 in the Egyptian desert {{convert|300|mi|km|-2|order=flip|abbr=on}} south of Cairo. The two men exceeded distance, endurance, and time records, traveling 19 days, 21 hours, and 55 minutes. 

===Briefest trip around the world===
[[Steve Fossett]], flying solo, exceeded the record for briefest time traveling around the world on 3 July 2002 on his sixth attempt,<ref>{{cite web |url=https://www.theguardian.com/travel/2016/sep/16/experience-flew-solo-round-world-hot-air-balloon |title=Experience: I flew solo around the world in a hot-air balloon |newspaper=The Guardian |date=17 September 2016|author=Fedor Konyukhov |access-date= 17 September 2016}} Article by Konyukhov describing the experience.</ref> in 320 h 33 min.<ref name=record-ballooning>{{cite web |url=http://www.fai.org/record-ballooning |title=Balloon World Records |publisher=Fédération Aéronautique Internationale |access-date=17 September 2016 |url-status=dead |archive-url=https://web.archive.org/web/20160908172221/http://www.fai.org/record-ballooning |archive-date=8 September 2016 }} Steve Fossett and Fedor Konyukhov, both sub-class AM-15.</ref> [[Fedor Konyukhov#Ballooning|Fedor Konyukhov]] flew solo round the world on his first attempt in a hybrid hot air/helium balloon from 11 to 23 July 2016<ref>{{cite web |url=https://www.fai.org/records?f%5B0%5D=field_record_sport%3A2027 |title=Fédération Aéronautique Internationale|website=Fédération Aéronautique Internationale|date= 20 June 2019 |access-date= 20 June 2019}}</ref> for a round-the world time of 268 h 20 min.<ref name=record-ballooning/>

==Construction==
A hot air balloon for manned flight uses a single-layered, fabric gas bag (lifting "envelope"), with an opening at the bottom called the mouth or throat. Attached to the envelope is a basket, or gondola, for carrying the passengers. Mounted above the basket and centered in the mouth is the "burner", which injects a flame into the envelope, heating the air within. The heater or burner is fueled by [[propane]], a [[Liquefied petroleum gas|liquefied gas]] stored in pressure vessels, similar to high-pressure [[Forklift truck|forklift]] [[Gas cylinder|cylinders]].<ref>{{cite web |url=http://www.pilotoutlook.com/balloon_flying/balloon_propane_tanks |title=Balloon Propane Tanks |publisher=Pilot Outlook |quote=Propane tanks used in hot air balloons are mainly constructed of either aluminum or stainless steel. Most aluminum tanks are vertical 10-gallon cylinders (DOT 4E240), built primarily for forklift trucks. |access-date=2010-06-05 |url-status=usurped |archive-url=https://web.archive.org/web/20110610072003/http://www.pilotoutlook.com/balloon_flying/balloon_propane_tanks |archive-date=2011-06-10 }}</ref><ref>{{cite web |url=http://www.propane101.com/propanecylinders.htm |title=Propane Cylinders |publisher=Propane 101 |quote=Cylinders in liquid service are commonly found on forklifts. |access-date=2010-06-05}}</ref>

===Envelope===
Modern hot air balloons are usually made of materials such as [[Ripstop#Ripstop nylon|ripstop nylon]] or [[Polyethylene terephthalate|dacron]] (a [[polyester]]).<ref name="eballoon">{{cite web |url=http://www.eballoon.org/balloon/envelope.html |title=The Envelope |website=Eballoon.org |access-date=2006-12-21}}</ref>

[[File:yellow.balloon.inflation.arp.jpg|thumb|right|A hot air balloon is inflated partially with cold air from a gasoline-powered fan, before the [[propane burner]]s are used for final inflation.]]
During the manufacturing process, the material is cut into panels and sewn together, along with structural [[Webbing|load tapes]] that carry the weight of the gondola or basket. The individual sections, which extend from the throat to the crown (top) of the envelope, are known as [[Gore (segment)|gores]] or gore sections. Envelopes can have as few as 4 gores or as many as 24 or more.<ref name="Head">{{cite web |url=http://home.att.net/~headballoons/second.htm |title=Head Balloons |access-date=2007-01-12 |archive-url=https://web.archive.org/web/20070110095942/http://home.att.net/~headballoons/second.htm |archive-date=2007-01-10 |url-status=dead }}</ref>

Envelopes often have a crown ring at their very top. This is a hoop of smooth metal, usually aluminium, and approximately {{convert|1|ft|cm|-1|order=flip|abbr=on}} in diameter. Vertical load tapes from the envelope are attached to the crown ring.

At the bottom of the envelope the vertical load tapes are sewn into loops that are connected to cables (one cable per load tape). These cables, often referred to as [[flying wires]], are connected to the basket by [[carabiner]]s.

====Seams====
The most common technique for sewing panels together is called the ''French [[Glossary of textile terminology|felled]]'', ''French fell'', or ''double lap'' seam.<ref>{{cite web |url=http://www.archsewing.com/newmachines/US_56900.html |title=Machine Style 56500 |publisher=Arch Sewing Company |year=2003 |quote=2 Needle Double Lap Seaming Also called Felled Seam |access-date=2010-03-06}}</ref><ref>{{cite web |url=http://www.xlta.org/plans/basics.html |title=Construction basics |quote=all of the seams are the "French fell" type |publisher=XLTA |author1=Daniel Nachbar |author2=Paul Stumpf |year=2008 |access-date=2010-03-06}}</ref><ref name = madehow>{{cite web |url=http://www.madehow.com/Volume-3/Hot-Air-Balloon.html |title=How Things Are Made: Hot Air Balloon, The Manufacturing Process |author=Annette Petrusso |publisher=Advameg |quote=The double lap seam features two rows of parallel stitching along the folded over fabric seam. A few manufactures use a flat seam. |access-date=2010-03-06}}</ref><ref>{{cite web |url=http://www.apexballoons.com/tips/ |title=How To Sew A Hot Air Balloon! |author=Jon Radowski |publisher=Apex Balloons |year=2010 |quote=perfect French Fell hot air balloon seam |access-date=2010-03-06}}</ref> The two pieces of fabric are folded over on each other at their common edge, possibly with a load tape as well, and sewn together with two rows of parallel stitching. Other methods include a ''flat lap'' seam, in which the two pieces of fabric are held together simply with two rows of parallel stitching, and a ''zigzag'', where parallel zigzag stitching holds a double lap of fabric.<ref name=madehow/>

====Coatings====
[[File:Ballooning Away in Maasai Mara.jpg|thumb|left|Hot air balloon safari in [[Maasai Mara]]]]
The fabric (or at least part of it, the top 1/3, for example) may be coated with a sealer, such as [[silicone]] or [[polyurethane]], to make it impermeable to air.<ref name="Cameron"/> It is often the degradation of this coating and the corresponding loss of impermeability that ends the effective life of an envelope, not weakening of the fabric itself. Heat, moisture, and mechanical wear-and-tear during set-up and pack-up are the primary causes of degradation. Once an envelope becomes too [[Porosity|porous]] to fly, it may be retired and discarded or perhaps used as a "rag bag": cold-inflated and opened for children to run through. Products for recoating the fabric are becoming available commercially.<ref name="MidAtlantic">{{cite web
| url = http://www.hotairrepair.com/recoating/
| title = Mid-Atlantic Balloon Repair: Balloon Envelope Fabric Recoating
| access-date = 2007-03-07}}</ref>

====Sizes and capacity====
A range of envelope sizes is available. The smallest, one-person, basket-less balloons (called "[[Hopper balloon|Hoppers]]" or "Cloudhoppers") have as little as {{convert|600|m3|cuft|abbr=on}} of envelope volume;<ref name="LindstrandUK">{{cite web
| url = http://www.lindstrand.co.uk
| title = Lindstrand Hot Air Balloons: Cloudhopper
| access-date = 2008-06-19
| archive-url = https://web.archive.org/web/20090701145406/http://www.lindstrand.co.uk/
| archive-date = 2009-07-01
| url-status = dead
}}</ref> for a perfect sphere the radius would be around {{convert|5|m|ft|abbr=on}}. At the other end of the scale, balloons used by commercial sightseeing operations may be able to carry well over two dozen people, with envelope volumes of up to {{convert|17000|m3|cuft|abbr=on}}.<ref name="LindstrandUK"/> The most-used size is about {{convert|2800|m3|cuft|abbr=on}}, allowing to carry 3 to 5 people.

====Vents====
[[File:Hot air balloon interior.jpg|thumb|right|The parachute vent at the top of an envelope, as seen from below through the mouth]]

The top of the balloon usually has a vent of some sort, enabling the pilot to release hot air to slow an ascent, start a descent, or increase the rate of descent, usually for landing. Some hot air balloons have ''turning vents'', which are side vents that, when opened, cause the balloon to rotate. Such vents are particularly useful for balloons with rectangular baskets, to facilitate aligning the wider side of the basket for landing.<ref>{{cite web
| url = http://www.avianballoon.com/envelope.html
| title = Avian Balloon Corporation: The Avian Envelope
| access-date = 2009-06-18
| archive-date = 2016-08-18
| archive-url = https://web.archive.org/web/20160818154726/http://www.avianballoon.com/envelope.html
| url-status = dead
}}</ref>

The most common type of top vent is a disk-shaped flap of fabric called a ''parachute vent'', invented by Tracy Barnes.<ref>{{cite web
| url = http://www.ballooninghistory.com/barnes/
| title = The early years of sport ballooning
| publisher = David M. Wesner
| access-date = 2010-06-09}}</ref> The fabric is connected around its edge to a set of "vent lines" that converge in the center. (The arrangement of fabric and lines roughly resembles a [[parachute]]—thus the name.) These "vent lines" are themselves connected to a control line that runs to the basket. A parachute vent is opened by pulling on the control line. Once the control line is released, the pressure of the remaining hot air pushes the vent fabric back into place. A parachute vent can be opened briefly while in flight to initiate a rapid descent. (Slower descents are initiated by allowing the air in the balloon to cool naturally.) The vent is pulled open completely to collapse the balloon after landing.

An older, and presently less commonly used, style of top vent is called a "[[Velcro]]-style" vent. This too is a disk of fabric at the top of the balloon. However, rather than having a set of "vent lines" that can repeatedly open and close the vent, the vent is secured by "hook and loop" fasteners (such as Velcro) and is only opened at the end of the flight. Balloons equipped with a Velcro-style vent typically have a second "maneuvering vent" built into the side (as opposed to the top) of the balloon. Another common type of top design is the "smart vent", which, rather than lowering a fabric disc into the envelope as in the "parachute" type, gathers the fabric together in the center of the opening. This system can theoretically be used for in-flight maneuvering, but is more commonly used only as a rapid-deflation device for use after landing, of particular value in high winds. Other designs, such as the "pop top" and "MultiVent" systems, have also attempted to address the need for rapid deflation on landing, but the parachute top remains popular as an all-around maneuvering and deflation system.

====Shape====
Besides special shapes, possibly for marketing purposes, there are several variations on the traditional "inverted tear drop" shape. The simplest, often used by home builders, is a [[Sphere|hemisphere]] on top of a truncated [[Cone (geometry)|cone]]. More sophisticated designs attempt to minimize the circumferential [[Stress (physics)|stress]] on the fabric, with different degrees of success depending on whether they take fabric weight and varying air density into account. This shape may be referred to as "natural".<ref>{{cite web
| url = http://www.myairship.com/building/design.html
| title = Airship and Blimp Resources: Balloon Envelope Design
| access-date = 2008-05-05}}</ref> Finally, some specialized balloons are designed to minimize [[aerodynamic drag]] (in the vertical direction) to improve flight performance in competitions.<ref>{{cite web
| url = http://www.balloonlife.com/2005/Aug-Sep05/racers.pdf
| title = What's the Skinny on Racing Balloons?
| access-date = 2008-05-05
| archive-url = https://web.archive.org/web/20120313143144/http://www.balloonlife.com/2005/Aug-Sep05/racers.pdf
| archive-date = 2012-03-13
| url-status = dead
}}</ref>

===Basket===
[[File:Hot Air Balloon Basket in Flight.jpg|thumb|upright=0.8 |left|Hot air balloon basket in flight]]
[[File:wicker.balloon.basket.bath.arp.jpg|thumb|A [[Wicker|wicker basket]] capable of holding 16 passengers]]

Hot air balloon baskets are commonly made of [[Basket weaving|woven]] [[wicker]] or [[rattan]]. These materials have proven to be sufficiently light, strong, and durable for balloon flight. Such baskets are usually rectangular or triangular in shape. They vary in size from just big enough for two people to large enough to carry thirty.<ref>{{cite web |url=http://uppner.se/Om-Upp-och-Ner.aspx |title=Ballongflyg Upp & Ner |access-date=2010-06-05 |archive-url=https://web.archive.org/web/20101113211335/http://www.uppner.se/Om-Upp-och-Ner.aspx |archive-date=2010-11-13 |url-status=dead}}</ref> Larger baskets often have internal partitions for structural bracing and to compartmentalize the passengers. Small holes may be woven into the side of the basket to act as foot holds for passengers climbing in or out.<ref>{{cite web
| url = http://www.eballoon.org/balloon/basket.html
| title = The Basket
| access-date = 2009-06-18}}</ref>

Baskets may also be made of [[aluminium]], especially a collapsible aluminium frame with a fabric skin, to reduce weight or increase portability.<ref>{{cite web
| url = http://aerostation.free.fr/mfr/en/mfr_3.shtml#experiment03
| title = Experimental Buildings: Collapsible Basket
| first = Arnaud
| last = Deramecourt
| year = 2002
| access-date = 2009-06-18}}</ref> These may be used by pilots without a ground crew or who are attempting to set altitude, duration, or distance records. Other specialty baskets include the fully enclosed gondolas used for around-the-world attempts<ref>{{cite web
| url = http://www.balloonlife.com/publications/balloon_life/9703/perint.htm
| title = Virgin Global Challenger: An Interview with Per Lindstrand
| year = 1997
| publisher = Balloon Life
| access-date = 2009-06-18
| archive-url = https://web.archive.org/web/20150923181822/http://www.balloonlife.com/publications/balloon_life/9703/perint.htm
| archive-date = 2015-09-23
| url-status = dead
}}</ref> and baskets that consist of little more than a seat for the pilot and perhaps one passenger.

===Burner===
[[File:Balloon fuel.jpg|thumb|upright=0.8|left|A burner directing a flame into the envelope]]
[[File:Luchtballon Brander.jpg|thumb|Burner]]

The burner unit gasifies liquid [[propane]],<ref>{{cite web
| url = http://www.eballoon.org/balloon/burner.html
| title = The Burner
| access-date = 2011-02-14}}</ref> mixes it with air, ignites the mixture, and directs the flame and exhaust into the mouth of the envelope. Burners vary in power output; each will generally produce 2 to 3&nbsp;MW of heat (7 to 10&nbsp;million [[British thermal unit|BTUs]] per hour), with double, triple, or quadruple burner configurations installed where more power is needed.<ref name="Kubicek">{{cite web
| url = http://www.kubicekballoons.cz/english/products/airships.php
| title = Hot Air Dirigible Specifications
| access-date = 2009-06-28
| archive-url = https://web.archive.org/web/20130515010349/http://www.kubicekballoons.cz/english/products/airships.php
| archive-date = 2013-05-15
| url-status = dead
}}</ref><ref name="RafficaOy">{{cite web
| url = http://www.kuumailmapallo.com/index.php?lang=UK&pageid=kalusto
| title = Example Balloon Configurations
| access-date = 2009-06-28}}</ref> The pilot actuates a burner by opening a propane valve, known as a '''blast valve'''. The valve may be spring-loaded, so that it closes automatically, or it may stay open until closed by the pilot. The burner has a [[pilot light]] to ignite the propane and air mixture. The pilot light may be lit by the pilot with an external device, such as a [[flint]] striker or a [[lighter]], or with a built-in [[Piezoelectricity|piezoelectric]] spark.<ref name="LindstrandFuel">{{cite web
| url = http://lindstrand.com/?id=14
| title = Lindstrand Fuel System: Burners & Tanks
| access-date = 2007-03-05}}</ref>

Where more than one burner is present, the pilot can use one or more at a time, depending on the desired heat output. Each burner has a metal coil of propane tubing the flame shoots through to preheat the incoming liquid propane. The burner unit may be suspended from the mouth of the envelope or supported rigidly over the basket. The burner unit may be mounted on a [[gimbal]] to enable the pilot to aim the flame and avoid overheating the envelope fabric. A burner may have a secondary propane valve that releases propane more slowly and thereby generates a different sound. This is called a ''whisper burner'' and is used for flight over livestock to lessen the chance of spooking them. It also generates a more yellow flame and is used for night glows because it lights up the inside of the envelope better than the primary valve.

===Fuel tanks===
Propane fuel tanks are usually cylindrical [[pressure vessel]]s made from [[aluminium]], [[stainless steel]], or [[titanium]] with a valve at one end to feed the burner and to refuel. They may have a [[fuel gauge]] and a [[Pressure measurement|pressure gauge]]. Common tank sizes are {{convert|10|,|15|and|20|usgal|L|order=flip|abbr=off}}.<ref name="Cameron"/> They may be intended for upright or horizontal use and may be mounted inside or outside the basket.

[[File:Hot air balloon fuel tanks.jpg|thumb|[[Stainless steel]] [[fuel tank]]s, wrapped in red insulating covers, mounted vertically, and with fuel gauges, during refueling]]

The pressure necessary to force the fuel through the line to the burner may be supplied by the [[vapor pressure]] of the propane itself, if warm enough, or by the introduction of an inert gas such as [[nitrogen]].<ref name="LindstrandFuel" /> Tanks may be preheated with electrical [[Trace heating|heat tapes]] to produce sufficient vapor pressure for cold-weather flying.<ref name="BalloonLife">{{cite web
 |url=http://www.balloonlife.com/publications/balloon_life/9612/nitrogen.htm 
 |title=Nitrogen vs. Heat Tapes 
 |access-date=2007-11-13 
 |url-status=dead 
 |archive-url=https://web.archive.org/web/20071011202602/http://www.balloonlife.com/publications/balloon_life/9612/nitrogen.htm 
 |archive-date=2007-10-11 
}}</ref> Warmed tanks are usually also wrapped in an insulating blanket to preserve heat during the setup and flight.

===Instrumentation===
A balloon may be outfitted with a variety of instruments to aid the pilot. These commonly include an [[altimeter]], a rate-of-climb (vertical-speed) indicator known as a [[variometer]], envelope (air) temperature, and ambient (air) temperature.<ref name="lindstrand">{{cite web
| url = http://www.lindstrand.com/instruments.php
| title = Flytec 3040 Digital Wireless Instrument Package
| access-date = 2006-12-26
| archive-url = https://web.archive.org/web/20120321023058/http://www.lindstrand.com/instruments.php
| archive-date = 2012-03-21
| url-status = dead
}}</ref> A [[Global Positioning System|GPS]] receiver can be useful to indicate ground speed (traditional aircraft air-speed indicators would be useless) and direction.

===Combined mass===
The combined mass of an average system can be calculated as follows:<ref name="Cameron" />
: {| class="wikitable"
|-
! Component
! Pounds
! Kilograms
! Mass fraction
|-
| {{convert|100000|cuft|m3|abbr=on|order=flip}} envelope
| align="right" |250
| align="right" |113.4
| {{percentage bar|3.3|width=200}}
|-
| 5-passenger basket
| align="right" |140
| align="right" |63.5
| {{percentage bar|1.9|width=200}}
|-
| Double burner
| align="right" |50
| align="right" |22.7
| {{percentage bar|0.7|width=200}}
|-
| 3 {{cvt|20|USgal|L|order=flip}} fuel tanks full of propane
| align="right" |3 × 135 = 405
| align="right" |183.7
| {{percentage bar|5.4|width=200}}
|-
| 5 passengers
| align="right" |5 × 150 = 750
| align="right" |340.2
| {{percentage bar|10.0|width=200}}
|-
| '''Subtotal'''
| align="right" |1595
| align="right" |723.5
| {{percentage bar|21.2|width=200}}
|-
| {{convert|100000|cuft|m3|abbr=on|order=flip}} of heated air*
| align="right" |5922
| align="right" |2686.2
| {{percentage bar|78.8|width=200}}
|-
| '''Total'''
| align="right" |(3.76&nbsp;tons) 7517
| align="right" |3409.7
| {{percentage bar|100.0|width=200}}
|}
:: <nowiki>*</nowiki> Using a [[Density of air|density]] of {{convert|0.9486|kg/m3|lb/cuft|abbr=on}} for dry air heated to {{convert|210|F|C|order=flip}}.

==Theory of operation==
===Generating lift===
Increasing the air temperature inside the envelope makes it less dense than the surrounding (ambient) air. The balloon floats because of the buoyant force exerted on it. This force is the same force that acts on objects when they are in water and is described by [[Buoyancy#Archimedes' principle|Archimedes' principle]]. The amount of lift (or [[buoyancy]]) provided by a hot air balloon depends primarily upon the difference between the temperature of the air inside the envelope and the temperature of the air outside the envelope. For most envelopes made of nylon fabric, the maximal internal temperature is limited to approximately 120&nbsp;°C (250&nbsp;°F).<ref>{{cite web
| url=http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/d7a71e4def72db7e862573e900555227/$FILE/A33CE.pdf
| archive-url=https://web.archive.org/web/20080624220610/http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/d7a71e4def72db7e862573e900555227/$FILE/A33CE.pdf
| archive-date=2008-06-24
| url-status=dead
| title=Department of Transportation, Federal Aviation Administration, Type certificate data sheet no. A33CE
| access-date=2008-06-16
}}</ref>

The melting point of nylon is significantly greater than this maximal [[operating temperature]]—about 230&nbsp;°C (450&nbsp;°F)—but higher temperatures cause the strength of the nylon fabric to degrade more quickly over time. With a maximal operating temperature of 120&nbsp;°C (250&nbsp;°F), balloon envelopes can generally be flown for between 400 and 500 hours before the fabric needs to be replaced. Many balloon pilots operate their envelopes at temperatures significantly less than the maximum to extend envelope-fabric life.

The lift generated by {{convert|100000|cuft|m3|order=flip|abbr=on}} of dry air heated to various temperatures may be calculated as follows:
: {| class="wikitable" style=text-align:center;
|-
! Air temperature {{break}} °C (°F)
! Air density {{break}} kg/m3 (lb/cu ft)
! Air mass {{break}} kg (lb)
! Lift generated {{break}}kg (lb)
|-
| {{cvt|20|C|abbr=values}}
| {{cvt|1.2041|kg/m3|lb/cuft|abbr=values}}
| {{cvt|3409.7|kg|abbr=values}}
| 0, (0)
|-
| {{cvt|99|C|abbr=values}}
| {{cvt|0.9486|kg/m3|lb/cuft|abbr=values}}
| {{cvt|2686.2|kg|lb|abbr=values}}
| {{cvt|723.5|kg|lb|abbr=values}}
|-
| {{cvt|120|C|abbr=values}}
| {{cvt|0.8978|kg/m3|lb/cuft|abbr=values}}
| {{cvt|2542.4|kg|lb|abbr=values}}
| {{cvt|867.3|kg|lb|abbr=values}}
|}

[[File:Infarot 9.jpg|thumb|left|Thermal image showing temperature variation in a hot air balloon]]
The [[density of air]] at {{cvt|20|C}} is about {{cvt|1.2|kg/m3|lb/cuft}}. The total lift for a balloon of {{cvt|100000|cuft|m3|order=flip}} heated to {{cvt|99|C}} would be {{cvt|723.5|kg|lb|0}}. This is just enough to generate neutral buoyancy for the total system mass (not including the heated air trapped in the envelope, of course) stated in the previous section. Liftoff would require a slightly greater temperature, depending on the desired rate of climb. In reality, the air contained in the envelope is not all at the same temperature, as the accompanying thermal image shows, and so these calculations are based on averages.

For typical atmospheric conditions ({{cvt|20|C|F|disp=or}}), a hot air balloon heated to {{cvt|99|C}} requires about 3.91&nbsp;m<sup>3</sup> of envelope volume to lift 1&nbsp;kilogram (equivalently, 62.5&nbsp;cu&nbsp;ft/lb). The precise amount of lift provided depends not only upon the internal temperature mentioned above, but the external temperature, altitude above sea level, and humidity of the air surrounding. On a warm day, a balloon cannot lift as much as on a cool day, because the temperature required for launch will exceed the maximum sustainable for nylon envelope fabric. Also, in the lower atmosphere, the lift provided by a hot air balloon decreases about 3% per 1,000&nbsp;m (1% per 1,000&nbsp;ft) of altitude gained.<ref>{{cite web
|url = http://www.overflite.com/thermo.html
|title = How to Calculate the Weight of Air and Model Hot Air Balloon Lift
|access-date = 2008-01-01}}</ref>

=== Types of Hot Air Balloons ===
There are several different types of hot air balloons, all with different means of taking and sustaining flight.

====Montgolfier====
[[File:Virgin_Hot_Air_Balloon.jpg|thumb|upright=0.8|A [[Virgin Balloon Flights|Virgin hot air balloon]] flying over [[Cambridge]]]]
Standard hot air balloons are known as '''Montgolfier balloons''' and rely solely on the buoyancy of hot air provided by the burner and contained by the envelope.<ref>{{cite web |title=NASA: Montgolfiere balloon missions for Mars and Titan |url=http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/38360/1/05-1506.pdf |url-status=dead |archive-url=https://web.archive.org/web/20080624220609/http://marstech.jpl.nasa.gov/publications/Jones_MontgolfiereBalloons_Inte.pdf |archive-date=2008-06-24 |access-date=2008-06-04}}</ref> This style of balloon was developed by the [[Montgolfier brothers]] and had its first public demonstration on 4 June 1783 with an unmanned flight lasting 10&nbsp;minutes, followed later that year with manned flights.<ref>[https://books.google.com/books?id=pDbQVE3IdTcC&dq=montgolfier+brothers+1783&pg=PA177 ''Scientific American Inventions and Discoveries''], p. 177, Rodney P. Carlisle, John Wiley and Sons, 2004, {{ISBN|0-471-24410-4}}.</ref>

==== Gas ====
[[File:1900 Olympic Ballooning - Pelouse p 252 of Report on Exposition Universelle.png|thumb|upright=1.15|[[1900 Olympics]] ballooning event at Le Parc d'aerostation, Paris<ref name="report">{{cite book|title=Exposition Universelle Internationale de 1900 a Paris. Concours Internationaux D'Exercices Physiques et de Sports. Rapports Publies Sous La Direction de M. D. Merillon.|author=Ministere du Commerce de L'Industrie des Postes et des Telegraphes|location=Paris |date=1902 |publisher=Imprimerie Nationale|pages=178, 250–275}}</ref>]]
Instead of using regular air it is also possible to use lighter than air gasses such as Helium or Hydrogen to lift the balloon,<ref>{{Cite web |title=Gas vs Hot |url=https://balloonfiesta.com/Gas-vs-Hot |access-date=2023-11-17 |website=balloonfiesta.com |language=en}}</ref> though this means it is technically not a hot air balloon, though they did influence the design of hybrid balloons.

====Hybrid====
[[File:Breitling_Orbiter_3_aloft.jpg|thumb|upright=0.8|During 1999, [[Bertrand Piccard]] and [[Brian Jones (aeronaut)|Brian Jones]] achieved the first non-stop balloon [[circumnavigation]] of the globe in ''[[Breitling Orbiter 3]]'', a Rozière/Hybrid balloon.]]
[[File:El mundo físico, 1882 "Primera ascensión aerostática de Pilatre de Roziers y de Arlandes el 21 de noviembre de 1783". (4031001655).jpg|thumb|Early depiction of hybrid balloon]]
The 1785 [[Rozière balloon]], is the main type of '''hybrid balloon''', named after its creator, Jean-François Pilâtre de Rozier. It has a separate cell for a lighter-than-air gas (typically [[helium]]), as well as a cone below for hot air (as is used in a hot air balloon) to heat the helium at night. [[Hydrogen]] gas was used in the very early stages of development but was quickly abandoned due to the danger of introducing an open flame near the gas, for example when Rozier attempted to cross the English Channel with his prototype, the fire used to heat the air ignited the Hydrogen and killed both him and his copilot thirty minutes after takeoff.<ref>{{Cite web |title=History Of Ballooning {{!}} National Balloon Museum |url=https://www.nationalballoonmuseum.com/about/history-of-ballooning/ |access-date=2023-11-17 |language=en-US}}</ref> As such, all modern hybrid balloons now use helium as a [[lifting gas]].<ref name="Amsbaugh">{{cite web |last=Amsbaugh |first=Allen |title=Balloon Incidents |url=http://asrs.arc.nasa.gov/publications/directline/dl9_balloon.htm |access-date=2009-01-16}}</ref> These balloons are commonly used for high performance records for hot air balloons.

====Solar====
[[File:Solarballon_Hot_18_Wikipedia.jpg|thumb|A four-meter-high solar balloon floating over a meadow]]
[[Solar balloon]]s are hot air balloons that use just [[Solar power#Solar thermal|solar energy]] captured by an envelope. These envelopes are more specialized than for other hot air balloons, trying to maximize the amount of solar energy they collect. This can be accomplished by rotating the envelope during flight or by having the envelope colored black or another dark color.<ref name="Solar">{{cite web |title=Solar Balloons |url=http://perso.orange.fr/ballonsolaire/en-index.htm |access-date=2007-10-29}}</ref> They were pioneered in the 1970s in Europe by Tracy Barnes, Dominic Michaelis, and in the US by Frederick Espoo and Paul Woessher.<ref>{{Cite web |title=Brief history of Solar Ballooning – Aerocene |url=https://aerocene.org/brief-history-solar-ballooning/ |access-date=2023-10-20 |language=en-US}}</ref>

====Thermal Airship====
[[File:Heissluft-Luftschiff Start THWZ 08.jpg|thumb|A [[Thermal airship]] being prepared for take-off during the "Warsteiner Internationale Montgolfiade" at [[Warstein]] ([[Germany]])]]
A [[Thermal airship]], or [[blimp]], became a reality in the 1960s. Thermal airships were the first steerable air buoyant vehicles.<ref name=":3">{{Cite news |title=The Difference Engine: Not all hot air |newspaper=The Economist |url=https://www.economist.com/babbage/2010/07/29/the-difference-engine-not-all-hot-air |access-date=2023-11-17 |issn=0013-0613}}</ref> They utilized tail fins and a rudder and contained strictly hot air rather than a mix with hydrogen or helium.<ref name=":3" />

====Observation Balloon====
[[Observation balloon]]s were deployed as early as the [[American Civil War]] and used as reconnaissance towers.<ref name=":0">{{Cite web |date=2015-01-09 |title=Balloons in the American Civil War |url=http://www.civilwar.com/weapons/observation-balloons.html |access-date=2023-10-26 |archive-url=https://web.archive.org/web/20150109154110/http://www.civilwar.com/weapons/observation-balloons.html |archive-date=2015-01-09 }}</ref> The first military funded balloon in America was designed by [[Thaddeus S. C. Lowe|Thaddeus Lowe]] on August 2, 1861, for the [[Union (American Civil War)|Union]].<ref name=":0" /> His design utilized gas from municipal lines to inflate the balloon as he did not have access to a portable generator.<ref name=":0" /> [[Observation balloon]]s during this time were all made using multicolored-silk, wicker baskets, and were vertically oriented and tear shaped.<ref name=":1">{{Cite web |date=2010-12-02 |title=Observation Balloons On The Western Front |url=http://www.westernfrontassociation.com/great-war-on-land/73-weapons-equipment-uniforms/313-ob-bal-west.html |access-date=2023-10-26 |archive-url=https://web.archive.org/web/20101202223810/http://www.westernfrontassociation.com/great-war-on-land/73-weapons-equipment-uniforms/313-ob-bal-west.html |archive-date=2010-12-02 }}</ref> Hydrogen, or [[Coal gas|illumination gas]] became the most used inflation fuel by the 20th Century, as it was lighter than air.<ref name=":1" /> [[Observation balloon]] usage skyrocketed in Britain by the [[Royal Engineers]] at the end of the 19th Century, deploying to Sudan in 1885 and to South Africa during the [[Second Boer War]] from 1899 to 1902.<ref>{{Cite web |date=2013-05-19 |title=Early military ballooning |url=http://www.rafmuseum.org.uk/research/online-exhibitions/rfc_centenary/british-military-aviation-1862-1912/early-military-ballooning.aspx |access-date=2023-10-26 |archive-url=https://web.archive.org/web/20130519072056/http://www.rafmuseum.org.uk/research/online-exhibitions/rfc_centenary/british-military-aviation-1862-1912/early-military-ballooning.aspx |archive-date=2013-05-19 }}</ref>

===Steering===
Due to the overall design of hot air balloons, controlled and precise steering of hot air balloons is not possible; it is possible for pilots to try to achieve basic directional control by changing altitude and catching different wind streams.<ref name=hotairflight>{{Cite web |title=How Do You Steer A Hot Air Balloon? (With Examples) |url=https://hotairflight.com/blog/steer-hot-air-balloon |access-date=2023-12-06 |website=Hot Air Flight |language=en}}</ref> Wind in the northern hemisphere tends to turn east due to [[coriolis effect]] as the altitude increases.

=== Landing ===
The most effective way of landing a hot air balloon is to reduce the energy in the envelope, either by turning down the flame in Montgolfier and Hybrid balloons, or more directly by opening a flap in the envelope that will release the air/gas inside.<ref name=hotairflight/>

==Safety equipment==
{{Unreferenced section|date=August 2009}}

To help ensure the safety of pilot and passengers, a hot air balloon may carry several pieces of safety equipment.

===Basket===
To relight the burner if the pilot light goes out and the optional piezo ignition fails, the pilot should have ready access to a means of backup ignition, such as a flint spark lighter. Many systems, especially those that carry passengers, have completely duplicate fuel and burner systems: two fuel tanks, connected to two separate hoses, which feed two distinct burners. This enables a safe landing in the case of a blockage somewhere in one system or if a system must be disabled because of a fuel leak.

A [[fire extinguisher]] suitable for extinguishing propane fires is useful. Most balloons carry a 1 or 2&nbsp;kg [[Fire classes|AB:E]] type fire extinguisher.<ref>{{Cite web |last=Annie |date=2021-05-21 |title=How Do Hot Air Balloons Not Catch On Fire? Read Here! |url=https://hotairflyer.com/how-balloons-not-catch-fire/ |access-date=2023-11-17 |website=hotairflyer.com |language=en-gb}}</ref>

A handling or drop line is mandatory safety equipment in many countries. This is a rope or webbing of 20–30&nbsp;meters in length attached to the balloon basket with a quick-release connection at one end. In very calm winds the balloon pilot can throw the handling line from the balloon so that the ground crew can guide the balloon safely away from obstructions on the ground.<ref>{{Cite web |title=Droplines {{!}} Crew Training |url=https://cazooee.com/crewing/dropline.html |access-date=2023-11-17 |website=cazooee.com}}</ref>

For commercial passenger balloons, a pilot restraint harness is mandatory in some countries. This consists of a hip belt and a webbing line that together allow for some movement while preventing the pilot from being ejected from the basket during a hard landing.

Further safety equipment may include a first-aid kit, a fire blanket and a strong rescue knife.

===Occupants===
At a minimum, the pilot should wear leather or flame-retardant fiber (such as [[nomex]]) gloves, so that they may shut off a gas valve in the case of a leak, even if there is a flame present; quick action in this regard can turn a potential catastrophe into a mere inconvenience. The pilot should additionally wear flame-resistant clothing covering their arms and legs; either natural fiber, such as [[cotton]], [[linen]], [[hemp]], or [[wool]], or engineered flame-retardant fiber, such as nomex, is acceptable in this capacity. Most engineered fibers (with the exception of [[rayon]], which is also safe to wear) are [[thermoplastic]]; many are also [[hydrocarbons]]. This makes such fabrics very much unsuitable to wear near high temperatures, since non-flame-retardant thermoplastics will melt onto the wearer, and most hydrocarbons, whether fibrous or not, are suitable to use as fuels. Natural fiber will singe rather than melt or burn readily, and flame-retardant fiber generally has a very high melting point and is intrinsically non-flammable. Many pilots also advise their passengers to wear similar protective clothing that covers their arms and legs, as well as strong shoes or boots that offer good ankle support. Finally, some balloon systems, especially those that hang the burner from the envelope instead of supporting it rigidly from the basket, require the use of helmets by the pilot and passengers.

===Ground crew===
The ground crew should wear gloves whenever there is a possibility of handling ropes or lines. The mass and exposed surface to air movement of a medium-sized balloon is sufficient to cause rope friction burns to the hands of anyone trying to stop or prevent movement. The ground crew should also wear sturdy shoes and at least long pants in case of the need to access a landing or landed balloon in rough or overgrown terrain.

==Maintenance and repair==
[[File:Balloonreflection.jpg|thumb|Taken from the basket, the reflection of the balloon can be seen in the lake below. Obstacles in the landscape can inhibit smooth retrieval of the balloon upon landing.]]

[[File:2015 Birds In Hand Balloons 02 image FRD.jpg|thumb|A commercial balloon ride approaching its landing site at [[Bird-in-Hand, Pennsylvania]]]]

As with aircraft, hot air balloons require regular maintenance to remain airworthy. As aircraft made of fabric and that lack direct horizontal control, hot air balloons may occasionally require repairs to rips or snags. While some operations, such as cleaning and drying, may be performed by the owner or pilot, other operations, such as sewing, must be performed by a qualified repair technician and recorded in the balloon's maintenance log book.

===Maintenance===
To ensure long life and safe operation, the envelope should be kept clean and dry. This prevents [[Mold (fungus)|mold]] and mildew from forming on the fabric and abrasion from occurring during packing, transport, and unpacking due to contact with foreign particles. In the event of a landing in a wet (because of precipitation or early morning or late evening dew) or muddy location (farmer's field), the envelope should be cleaned and laid out or hung to dry.

The burner and fuel system must also be kept clean to ensure safe operation on demand. Damaged fuel hoses need to be replaced. Stuck or leaky valves must be repaired or replaced. The wicker basket may require occasional refinishing or repair. The skids on its bottom may require occasional replacement.

Balloons in most parts of the world are maintained in accordance with a fixed manufacturer's maintenance schedule that includes regular (100 flight hours or 12 month) inspections, in addition to maintenance work to correct any damage. In Australia, balloons used for carrying commercial passengers must be inspected and maintained by approved workshops.<ref>{{cite web
| url = https://www.brisbanehotairballooning.com.au/ballooning-basics/
| title = Ballooning Basics
| access-date = 2019-07-26}}</ref>

===Repair===
In the case of a snag, burn, or rip in the envelope fabric, a patch may be applied or the affected panel completely replaced. Patches may be held in place with glue, tape, stitching, or a combination of these techniques. Replacing an entire panel requires the stitching around the old panel to be removed, and a new panel to be sewn in with the appropriate technique, thread, and stitch pattern.

==Licensing==
Depending on the size of the balloon, location, and intended use, hot air balloons and their pilots need to comply with a variety of regulations.

===Balloons===
[[File:Setting up hot air balloon, Poughkeepsie, NY 2.JPG|thumb|Top of balloon during inflation. [[Crew]] is securing parachute vent.]]

As with other aircraft in the US, balloons must be registered (have an [[Aircraft registration|N-number]]), have an [[airworthiness]] certificate, and pass annual inspections. Balloons below a certain size (empty weight of less than 155&nbsp;pounds or 70&nbsp;kg including envelope, basket, burners and empty fuel tanks) can be used as an [[Ultralight aircraft (United States)|ultralight aircraft]].

===Pilots===
====In Australia====
In Australia, private balloon pilots are managed by the Australian Ballooning Federation<ref>{{cite web
| url = http://www.abf.net.au/
| title = Australian Ballooning Federation
| access-date = 2015-03-28}}</ref>
and typically become members of regional hot air ballooning clubs. Commercial operations carrying fare paying passengers or charging for promotional flights must operate under an Air Operators Certificate from the Australian Civil Aviation and Safety Authority (CASA) with a nominated Chief Pilot. Pilots must have different degrees of experience before they are allowed to progress to larger balloons. Hot air balloons must be registered aircraft with CASA and are subject to regular airworthiness checks by authorised personnel.<ref>{{cite web
| url = http://www.hotair.com.au/pages/FAQs.html#faq15
| title = Hot Air FAQ: What regulations are in Place?
| access-date = 2009-06-22
| archive-url = https://web.archive.org/web/20100110215940/http://www.hotair.com.au/pages/FAQs.html#faq15
| archive-date = 2010-01-10
| url-status = dead
}}</ref>

====In the UK====
In the UK, the person in command must hold a valid Private Pilot's Licence issued by the Civil Aviation Authority specifically for ballooning; this is known as the PPL(B). There are two types of commercial balloon licences: CPL(B) Restricted and CPL(B) (Full). The CPL(B) Restricted is required if the pilot is undertaking work for a sponsor or being paid by an external agent to operate a balloon. The pilot can fly a sponsored balloon with everything paid for with a PPL unless asked to attend any event. Then a CPL(B) Restricted is required. The CPL(B) is required if the pilot is flying passengers for money. The balloon then needs a transport category C of A (certificate of air worthiness). If the pilot is only flying sponsor's guests and not charging money for flying other passengers, then the pilot is exempted from holding an AOC (air operator's certificate) though a copy of it is required.{{Clarify|date=February 2013|reason=how can pilot have copy of license not held?}} For passenger flying the balloon also requires a maintenance log.

====In the United States====
In the United States, a pilot of a hot air balloon must have a [[Pilot certification in the United States|pilot certificate]] from the [[Federal Aviation Administration]] (FAA), carrying the rating of "Lighter-than-air free balloon", and unless the pilot is also qualified to fly gas balloons, will also carry this limitation: "Limited to hot-air balloons with airborne heater". A pilot does not need a license to fly an [[Ultralight aviation|ultralight]] aircraft, but training is highly advised, and some hot-air balloons meet the criteria.

To carry paying passengers for hire (and attend some [[Hot air balloon festival|balloon festivals]]), a pilot must have a [[Pilot certification in the United States#Commercial|commercial pilot certificate]]. Commercial hot air balloon pilots may also act as hot air balloon [[flight instructor]]s. While most balloon pilots fly for the pure joy of floating through the air, many are able to make a living as a professional balloon pilot. Some professional pilots fly commercial passenger sightseeing flights, while others fly corporate advertising balloons.<ref name="Professional Pilots">{{cite web
| url = http://www.hotairballooning.com/balloon-pilot.php
| title = Professional Balloon Pilots
| access-date = 2007-05-03
| archive-date = 2016-10-24
| archive-url = https://web.archive.org/web/20161024030105/http://www.hotairballooning.com/balloon-pilot.php
| url-status = dead
}}</ref>

==Accidents and incidents==
<!--note most accidents and incidents are NOT notable enough to be mentioned here. Only the most serious accidents or those involving Wikinotable people should be included.-->
{{further|History of ballooning#Notable accidents}}
* [[1989 Alice Springs hot air balloon crash]]: On 13 August 1989, two hot air balloons collided at [[Alice Springs, Northern Territory]], Australia, causing one to fall, killing all 13 people on board.
* [[2011 Somerset hot air balloon crash]]: On 1 January 2011, a hot air balloon attempting a high-altitude flight crashed at Pratten's Bowls Club in [[Westfield, Somerset]], near [[Bath, Somerset|Bath]], England, killing both people on board.
* [[2012 Carterton hot air balloon crash]]: On 7 January 2012, a hot air balloon collided with a power line, caught fire and crashed at [[Carterton, North Island]], New Zealand, killing all 11 people on board.
* [[2012 Ljubljana Marshes hot air balloon crash]]: On 23 August 2012, a storm blew a hot air balloon to the ground, causing it to catch fire on impact near [[Ljubljana]], Slovenia. The crash killed 6 of the 32 people on board, and injured the other 26.
* [[2013 Luxor hot air balloon crash]]: On 26 February 2013, a hot air balloon carrying foreign tourists ignited and crashed near the ancient city of [[Luxor]], Egypt, killing 19 of the 21 people on board, making it the deadliest balloon accident in history.<ref name="SMH Egypt">{{cite news|url=http://worldnews.nbcnews.com/_news/2013/02/26/17096440-foreign-tourists-killed-in-egypt-balloon-crash?lite=|title=Foreign tourists killed in Egyptian balloon crash|last1=Mohyeldin|first1=Ayman|date=26 February 2013|work=World News on NBCNews.com|archive-url=https://web.archive.org/web/20130301045548/http://worldnews.nbcnews.com/_news/2013/02/26/17096440-19-tourists-die-as-hot-air-balloon-catches-fire-in-egypt?lite=|archive-date=1 March 2013|last2=Gubash|first2=Charlene|last3=Newland|first3=John|access-date=26 February 2013|url-status=dead}}</ref>
* [[2016 Lockhart hot air balloon crash]]: On 30 July 2016, a hot air balloon carrying 16 people caught fire and crashed near [[Lockhart, Texas]]. There were no survivors.
* [[2021 Albuquerque hot air balloon crash]]: On 26 June 2021, a hot air balloon carrying five people made contact with a power line and crashed in [[Albuquerque, New Mexico]]. All five people on board died as a result of the accident.
* On 14 January 2024, a hot air balloon crashed outside Eloy, Arizona,<ref>{{cite news|title=Balloon accident in Eloy, Arozona|url=https://www.azcentral.com/story/news/local/arizona/2024/01/14/hot-air-balloon-crash-in-eloy-leaves-4-dead-1-injured/72227355007/}}</ref> killing the three passengers and pilot. Eight skydivers had exited the balloon immediately prior to the incident.
* [[2025 Santa Catarina hot air balloon crash]]: On 21 June 2025, a hot air balloon crashed after caught fire in [[Praia Grande, Santa Catarina]], Brazil, killing 8 of the 21 people on board.<ref name=bbc> {{cite news|first1=Rute|last1=Pina|first2=Jaroslav|last2=Lukiv|title=At least eight dead in hot air balloon accident in Brazil |url=https://www.bbc.com/news/articles/c17w04wxwpxo |work=[[BBC]] |date=21 June 2025}}</ref><ref name=cnn>{{Cite web|url=https://www.cnn.com/2025/06/21/americas/dead-hot-air-balloon-accident-brazil-intl|title=At least 8 dead after hot air balloon accident in southern Brazil|first1=Duarte|last1=Mendonca|first2=Eve|last2=Brennan|date=21 June 2025|website=[[CNN]]|accessdate=21 June 2025}}</ref>

==Manufacturers==
[[File:2017 Cameron Balloon designed by Seattle Ballooning .jpg|thumb|New 2017 Cameron hot air balloon in flight<!-- ref>{{cite web |url=full URL |title=and title are needed |website=seattleballooning.com}}</ref -->]]

The largest manufacturer of hot air balloons is [[Cameron Balloons]] of [[Bristol]], England, which also owns [[Lindstrand Balloons]] of [[Oswestry]], England. Cameron Balloons, Lindstrand Balloons and another English balloon manufacturing company [[Thunder and Colt]] (since acquired by Cameron) have been innovators and developers of special shaped balloons. These hot-air balloons use the same principle of lift as conventional inverted teardrop-shaped balloons, but often sections of the special balloon envelope shape do not contribute to the balloon's ability to stay aloft.

The second largest manufacturer of hot air balloons is [[Ultramagic]] company, based in Spain, which produces from 80 to 120 balloons per year. Ultramagic can produce very large balloons, such as the N-500 that accommodates as many as 27 persons in the basket, and has also produced many balloons with special shapes, as well as cold-air inflatables.

One of the three largest companies in the world is [[Kubicek Balloons]]. From its factory in [[Brno]], [[Czech Republic|Czechia]] the company ships its products worldwide. Produces from 100 to 115 balloons per year. Kubicek company also focus on special shape balloons, FAA/EASA type certified and are delivered with a Standard Airworthiness Certificate.

[[File:Guru Balloon guruballoon.com 407.758.7007.jpg|thumb|One of the last Aerostar International, Inc. RX8 balloons]]

In the USA [[Raven Industries|Aerostar International, Inc.]] of [[Sioux Falls, South Dakota]] was North America's largest balloon manufacturer and a close second in world manufacturing before ceasing to build balloons in January 2007. The oldest U.S. certified manufacturer is now Adams Balloons out of Albuquerque, New Mexico. [[Firefly Balloons]], formerly The Balloon Works, is a manufacturer of hot air balloons in [[Statesville, North Carolina]]. Another manufacturer is [[Head Balloons, Inc.]] of [[Helen, Georgia]].

The major manufacturers in Canada are [[Sundance Balloons]] and [[Fantasy Sky Promotions]]. Other manufacturers include Kavanagh Balloons of Australia, Schroeder Fire Balloons of Germany, [[Kubicek Balloons]] of the Czech Republic, and LLopis Balloons of France.

==See also==
{{div col|colwidth=15em}}
* [[Aerostat]]
* [[Barrage balloon]]
* [[Blimp]]
* [[Cluster ballooning]]
* [[Espionage balloon]]
* [[Gas balloon]]
* [[High-altitude balloon]]
* [[History of military ballooning]]
* [[Hot air balloon festival]]
* [[Hot air ballooning]]
* [[Observation balloon]]
* [[Research balloon]]
* [[Skyhook balloon]]
{{div col end}}

==References==
{{Reflist|refs=
<ref name="Cameron">{{cite web
| url = http://www.cameronballoons.com/tanks.html
| title = Cameron Balloons Fuel Tanks
| access-date = 2007-03-07}}</ref>
}}
* Needham, Joseph (1986).'' Science and Civilization in China: Volume 4, Physics and Physical Technology, Part 2, Mechanical Engineering''. Taipei: Caves Books Ltd.

==External links==
{{Commons}}
{{Library resources box|label=hot air balloons|onlinebooks=yes}}

===General ballooning sites===
* [http://www.euronet.nl/users/jdewilde/index.html Hot Air Balloon Web Links]

{{Accidents and incidents involving hot air balloons}}

{{Authority control}}

[[Category:18th-century inventions]]
[[Category:Balloons (aeronautics)]]
[[Category:Airship technology]]
[[Category:Symbols of New Mexico]]
[[Category:French inventions]]

[[ang:Ballōn (lyftcræft)#Hātlyftballōn]]