thumb|right|'n Warmlugballon in vlug

Die '''warmlugballon''' is die eerste suksesvolle passasiersdraende lugvaarttegnologie wat ontwikkel is en dateer terug tot die uitvinding daarvan deur die Montgolfier broers in Annonay, Frankryk in 1783.  Die eerste vlug wat mense saamgedra het is op die 21<sup>de</sup> November 1783 in Parys onderneem deur Jean-François Pilâtre de Rozier en François Laurent d'Arlandes.

Warmlugballonne wat deur die lug aangedryf kan word eerder as om bloot deur die wind rondgestoot te word, staan bekend as 'n lugskip en meer spesifiek 'n termiese lugskip.

'n Warmlugballon bestaan uit 'n sak wat die vermoë het om die verhitte lug binne te hou.  Daaronder word 'n gondola of mandjie gehang (in sommige ballonne wat baie hoog vlieg word 'n lugdigte kapsule daaronder gehang) wat die passasiers en die hittebron/-opwekker dra.  Die verhitte lig in die ballon maak dat die lug dryf aangesien dit 'n laer digtheid het as die relatief kouer lug buite die ballon.  Anders as gasballonne hoef dit nie onder geseël te word nie aangesien die stygende warm lug slegs druk op die boonste deel van die ballon uitoefen.  Vandag se sportballonne word oor die algemeen uit Nylon vervaardig en die mond van die ballon (naby aan die brander) word van 'n brandbestande materiaal soos NOMEX ('n Produk van DuPont) vervaardig.

Onlangs het mense begin om ballonne in allerhande buitengewone vorme te vervaardig, soos worsbroodjies, vuurpyle of die vorm van kommersiële produkte.

==Geskiedenis==
===Voormoderne tyd===
thumb|'n [[Kongming lantern, die oudste soort warmlugballon.]]
Onbemande warmlugballonne was nog altyd gewild in Sjinese geskiedenis. Zhuge Liang van die Shu Han koninkryk in die tydperk van die drie koninkryke, het warmluglanterns vir militêre seindoeleindes aangewend.  Hierdie lanterns staan bekend as Kongming lanterns.<ref>[http://books.google.com/books?id=ssO_19TRQ9AC&pg=PA113&ots=vDEuq_hKqc&dq=Kongming+balloon&sig=c3NT-uzoBYhzq203Qofw6XR9MH0 http://books.google.com/books?id=ssO_19TRQ9AC&pg=PA113&ots=vDEuq_hKqc&dq=Kongming+balloon&sig=c3NT-uzoBYhzq203Qofw6XR9MH0 Ancient Chinese Inventions]</ref><ref>[http://library.thinkquest.org/23062/balloon.html http://library.thinkquest.org/23062/balloon.html - The Ten Thousand Infallible Arts of the Prince of Huai-Nan]</ref>

Daar word ook gegis dat warmlugballonne sowat 1500 jaar gelede deur die Nazca indiane van reuse tekeninge op die Nazca vlakte.<ref>[http://www.nott.com/Pages/projects.php http://www.nott.com/Pages/projects.php The Extraordinary Nazca Prehistoric Balloon]</ref>

'n Metode om voorwerpe op hul eie in die lug te laat dryf met behulp van warm lug is bespreek deur die 11<sup>de</sup> eeuse Joodse geleerde Rashi in sy kommentaar op die Bybel.<ref>Rashi Exodus Hoofstuk 16 Vers 14</ref>

===Die eerste aangetekende bemande ballonvlug===
thumb|Hierdie 1818 tegniese tekening wys hoe vroeë ballonne ontwerp is.
Die eerste aangetekende gevalle van ballonne wat die vermoë gehad het om passasiers te dra deur van die dryfvermoë van warmlug gebruik te maak is deur die broers Joseph-Michel en Jacques-Etienne Montgolfier in Annonay, Frankryk gebou.  Hierdie broers was afkomstig uit 'n familie wat betrokke was by die vervaardiging van papier en hulle inspirasie het gekom toe hulle gesien het hoe die as in vuur na bo styg.  Nadat hulle met onbemande ballonne geëksperimenteer het en met ballonne wat diere gedra het, het die eerste ballonvaart met mense aan boord op 19 Oktober 1783 plaasgevind met die wetenskaplike Jean-François Pilâtre de Rozier, Jean-Baptiste Réveillon en Giroud de Villette aan boord by die ''Folie Titon'' in Parys (Hierdie ballon was egter steeds met 'n tou aan die grond vasgeanker).  Die amptelike vrye vlug het eers 'n maand later plaasgevind op 21 November 1783.<ref>http://www.start-flying.com/Montgolfier.htm, Start-Flying: history of balloon flying, 2007-12-28</ref><ref>http://www.chm.bris.ac.uk/webprojects2003/hetherington/final/montgolfier_bros.html, Lighter than air: The Montgolfier Brothers, 2007-12-28</ref><ref>http://www.nasm.si.edu/exhibitions/gal109/NEWHTF/ITM300.HTM, National Air and Space Museum: Pioneers of Flight gallery, nagegaan op 2007-12-28</ref>  Die eerste warmlugballonne was basies materiaalsakke (soms met papier uitgevoer) met 'n rokende vuur op 'n rooster onderaan.

===Hedendaags===
Vandag word warmlugballonne hoofsaaklik vir ontspanning gebruik.  In Suid-Afrika is BAFSA, 'n afdeling van die Aero Klub van Suid-Afrika, die beherende liggaam ten opsigte van die administrasie van ballonsport en -ontspanning.  BAFSA reël ook die jaarlikse Suid-Afrikaanse warmlugballonkampioenskappe.<ref>http://www.bafsa.co.za/ BAFSA se amptelike webwerf</ref>  Een van die groot gebeurtenisse op die internasionale warmlugballonkalender is die Warmlugballon Fiesta te Albuquerque in die V.S.A.

Warmlugballonne kan uiters hoë hoogtes bereik.  Op 25 November 2005 het Vijapat Singhania die wêreld hoogterekord vir warmlugballonne opgestel deur 21 290 m hoog te vlieg.<ref>http://in.news.yahoo.com/051126/137/618bs.html Nuusberig oor Vijaypat Singhania se rekord</ref>  Soos met alle ander gelisensieërde vliegtuie moet suurstof verskaf word vir enige vlug wat 3 810 m oorskry.

Op 15 Januarie 1991 het die ''Virgin Pacific Flyer'' ballon die langste vlug in 'n warmlugballon voltooi toe Noord-Kanada gevlieg het.  Hierdie ballon met sy 74 duisend straalstrome te vlieg en het ook die vinnigste grondsnelheid vir 'n bemande ballon aangeteken van 394 km/h.

Die warmballonvlug wat die langste geduur het is deur Michio Kanda en Hirosuke Tekezawa van Japan op 2 Januarie 1997 tydens 'n vlug wat 50 uur en 38 minute geduur het.<ref>http://records.fai.org/balloons/current.asp?id1=ax&id3=3&id2=1 Wêreldrekords met Ballonne aangeteken</ref>

==Konstruksie==
'n Warmlugballon vir bemande vlugte gebruik 'n enkellaag materiaalsak met 'n opening aan die onderkant.  Onderaan die sak hang 'n mandjie of gondola om passasiers te dra.  Die mandjie word gewoonlik van riet of rottang vervaardig, maar kan ook uit aluminium vervaardig word.  Bo aan die mandjie en presies in die middel onder die opening word 'n brander gemonteer wat die vlam in die sak inspuit sodat die lug daarbinne verhit kan word.  Die brander word met propaan, 'n vloeibare petroleumgas (VPG) gevoer wat in hoëdruk silinders gestoor word.

===Ballonsak===
Moderne warmlugballonne word gewoonlik vervaardig uit ligte sterk sintetiese materiale soos dacron ('n soort poli-ester).<ref name="eballoon">http://www.eballoon.org/balloon/envelope.html, eballoon.org, 2006-12-21</ref>

thumb|right|'n Warmlugballon word gedeeltelik opgeblaas met koue lug vanaf 'n petrolaangedrewe waaier voordat die propaanbranders ingespan word om dit volledig op te blaas.

Tydens die vervaardigingsproses word die materiaal in panele gesny en aanmekaar gestik saam met die strukturele seilband (webbing) wat die gewig van die gondola of mandjie moet dra.  Die warmlugballon kan saamgestel word uit so min as 4 of soveel as 24 of selfs meer panele.<ref name="Head">http://home.att.net/~headballoons/second.htm, Head Balloons, 2007-01-12</ref>

Die ballonsak word dikwels van 'n kroonring aan die bokant voorsien.  Hierdie ring is 'n gladde metaalhoepel, gewoonlik aluminium en is ongeveer 300 mm in deursnee en die seilbande word daaraan vasgebind.

====Materiaalbekledings====
Die materiaal (of 'n gedeelte daarvan, soos die boonste ⅓ daarvan) kan bedek word met 'n seëlaar, soos silikoon of poli-uretaan om dit ondeurlaatbaar vir lug (lugdig) te maak.<ref name="Cameron">http://www.cameronballoons.com/hyperlast.html, Cameron Balloons Hyperlast, 2006-12-21</ref>  Dit is dikwels hierdie agteruitgang van die bekleding en die daarmee gepaardgaande verhoogde deurlaatbaarheid vir lug wat die ballonsak nie meer lugwaardig maak nie en nie die verswakking van die materiaal self nie.  Hitte, vog en die meganiese slytasie tydens die opstel en verpakking van die ballonsak is die primêre oorsake van die agteruitgang daarvan.  Daar bestaan wel produkte vir die herbekleding van die materiaal.<ref name="MidAtlantic">http://www.hotairrepair.com/recoating/, Mid-Atlantic Balloon Repair: Balloon Envelope Fabric Recoating, 2007-03-07</ref>

====Sakgroottes====
Ballonsakke is gewoonlik in verskeie groottes beskikbaar.  Die kleinste eenpersoon mandjielose ballonne (Hoppers genoem) het minder as 1 000 m<sup>3</sup> sakvolume (vir 'n perfekte sfeer sou dié volume ooreenstem met 13.3 meter.  Aan die ander kant van hierdie skaal is die ballonne wat deur kommersiële besigtigingstoer-maatskappye gebruik word en meer as twee dosyn mense kan dra met volumes van soveel as 15 000 m<sup>3</sup>.  Die meeste ballonne kan gewoonlik so 3 tot 4 mense dra en het 'n volume van 2 500 m<sup>3</sup>

====Uitlate====
thumb|right|Die valskermuitlaat aan die bokant van die ballonsak, soos gesien van onder deur die mond.
Die bokant van die ballon word gewoonlik met die een of ander soort uitlaat voorsien.  Die mees algemene soort uitlaat is 'n ronde flap of ''valskermuitlaat''.  Die materiaal word aan sy rante voorsien met 'n stel ventilasielyne wat in die middel bymekaarkom.  Die ventilasielyne word op hul beurt aan 'n beheertou verbind wat tot in die mandjie loop.  'n Valskermuitlaat word oopgemaak deur aan die beheertou te trek.  As die beheertou losgelaat word, word die uitlaatflap deur die warm lug terug in sy plek gedruk.  'n Valskermuitlaat kan vir 'n kort tydperk oopgemaak word tydens vlug indien dit nodig sou wees om vinnig te daal.  (Gewoonlik word stadiger dalings bewerkstellig deur die lug in die ballon toe te laat om natuurlik af te koel).  Die uitlaat word heeltemal oopgetrek na landing om die ballon heeltemal af te blaas. 

thumb|right|Hot air balloon in flight
thumb|right|Hot air balloons shaped as bees.
thumb|right|Hot air balloon shaped as a turtle.
The '''hot air balloon''' is the oldest successful human-carrying flight technology. On November 21, 1783, in Paris, France, the first manned flight was made by Jean-François Pilâtre de Rozier and François Laurent d'Arlandes in a hot air balloon created by the Montgolfier brothers.

A hot air balloon consists of a bag called the envelope that is capable of containing heated air. Suspended beneath is the gondola or capsule) which carries the passengers and a source of heat. The heated air inside the envelope makes it lower density than the relatively cold air outside the envelope. Unlike gas balloons, the envelope does not have to be sealed at the bottom since the air near the bottom of the envelope is at the same pressure as the surrounding air. In today's sport balloons the envelope is generally made from nylon fabric and the mouth of the balloon (closest to the burner flame) is made from fire resistant material such as Nomex.

Recently, balloon envelopes have been made in all kinds of shapes, such as hot dogs, rocket ships, and the shapes of commercial products. Hot air balloons that can be propelled through the air rather than just being pushed along by the wind are known as airships or, more specifically, thermal airships.

==History==

===Premodern and unmanned balloons===
thumb|A [[Kongming lantern, the oldest type of hot air balloon.]]
Unmanned hot air balloons are popular in Chinese history. Nazca ground figures and lines.<ref>{{cite web
| url = http://www.nott.com/Pages/projects.php
| title = The Extraordinary Nazca Prehistoric Balloon
| accessdate = 2008-05-06}}</ref> The first documented balloon flight in Europe was by the Portuguese priest John V and the Portuguese court.<ref> AMEIDA, L. Ferrand de, "Gusmão, Bartolomeu Lourenço de", in SERRÃO, Joel, Dicionário de História de Portugal, Porto, Figueirinhas, 1981, vol. III, pp. 184-185 </ref>

===First manned flight===
thumb|left|A model of the Montgolfier brothers balloon at the [[London Science Museum]] 

The first clearly recorded instance of a balloon carrying passengers used hot air to generate Montgolfier in Annonay, France.  After experimenting with unmanned balloons and flights with animals, the first ''tethered'' balloon flight with humans on board took place on October 19 1783 with the scientist Jean-François Pilâtre de Rozier, the manufacture manager, Jean-Baptiste Réveillon and Giroud de Villette, at the ''Folie Titon'' in Paris. The first ''free'' flight with human passengers was on 21 November 1783.<ref>{{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 
| accessdate = 2008-06-04}}</ref> King Louis XVI had originally decreed that condemned criminals would be the first pilots, but de Rozier, along with Marquis Francois d'Arlandes, successfully petitioned for the honor.<ref>{{cite web
| url = http://www.start-flying.com/Montgolfier.htm
| title = Start-Flying: history of balloon flying
| accessdate = 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
| accessdate = 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 
| accessdate = 2007-12-28}}</ref>

===Today===
right|thumb|A pair of Hopper balloons.
Modern hot air ballons, with an onboard heat source, were pioneered by Ed Yost beginning in the 1950s which resulted in his first successful flight on October 22, 1960.<ref>{{cite web
| url = http://www.nytimes.com/2007/06/04/us/04yost.html?_r=1&oref=slogin
| title = ''New York Times'': Ed Yost, 87, Father of Modern Hot-Air Ballooning, Dies
| accessdate = 2008-06-04}}</ref> The first modern day hot air balloon to be built in the United Kingdom (UK) was the Bristol Belle in 1967. Today, hot air balloons are used primarily for recreation, and there are some 7,500 hot air balloons operating in the United States.  

Hot air balloons are able to fly to extremely high altitudes. On November 26, 2005, Vijaypat Singhania set the world altitude record for highest hot air balloon flight, reaching . He took off from downtown Bombay, India and landed  south in Panchale.<ref> {{cite web
|url = http://www.prdomain.com/upload/104/10443872.pdf
|title = Dr. Vijaypat Singhania enters the Guinness World Records
|accessdate = 2008-06-22}}</ref> The previous record of  had been set by Per Lindstrand on June 6, 1988 in Plano, Texas. As with all registered aircraft, oxygen is needed for all crew and passengers for any flight that reaches and exceeds an altitude of .

<!-- Deleted image removed: thumb|right|The ''[[Virgin Group|Virgin Pacific Flyer'' capsule on a frozen lake in the Canadian jettisonable propane fuel tanks are no longer attached. One still hangs in front of the two-man sealed pressurized capsule. The flight holds the distance record for a hot air balloon.]] -->
On cubic meters (2.6 million cubic feet), the balloon envelope was the largest ever built for a hot air craft. Designed to fly in the trans-oceanic jet streams the ''Pacific Flyer'' recorded the highest ground speed for a manned balloon at .

The longest duration hot air balloon flight ever made is 50 hours and 38 minutes made by 
Michio Kanda and Hirosuke Tekezawa of Japan on January 2, 1997.<ref>[http://records.fai.org/balloons/current.asp?id1=ax&id3=3&id2=1 Balloon World Records]</ref>

==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 liquefied gas stored in pressure vessels, similar to high pressure forklift cylinders.

===Envelope===
Modern hot air balloons are usually made of light-weight and strong synthetic fabrics such as dacron (a polyester).<ref name="eballoon">{{cite web
| url = http://www.eballoon.org/balloon/envelope.html
| title = eballoon.org
| accessdate = 2006-12-21}}</ref>

thumb|right|A hot air balloon is partially inflated with cold air from a gas-powered fan, before the propane burners are used for final inflation.

During the manufacturing process, the material is cut into panels and sewn together, along with structural load tapes (webbing) that carry the weight of the gondola or basket. The individual sections which run from the throat to the crown (top) of the envelope are called 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
| accessdate = 2007-01-12}}</ref>

Envelopes often have a crown ring at their very top. This is a hoop of smooth metal, usually aluminum and approximately  in diameter, to which vertical load tapes attach.

====Fabric coatings====
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">{{cite web
| url = http://www.cameronballoons.com/hyperlast.html
| title = Cameron Balloons Hyperlast
| accessdate = 2006-12-21}}</ref> 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 porous to fly, it may be retired and used as a 'rag bag': cold inflated and opened for children to run through. Products for recoating the fabric are becoming commercially available.<ref name="MidAtlantic">{{cite web
| url = http://www.hotairrepair.com/recoating/
| title = Mid-Atlantic Balloon Repair: Balloon Envelope Fabric Recoating
| accessdate = 2007-03-07}}</ref>

====Sizes====
<!-- Unsourced image removed: thumb|right|Free inflation in the [[Ferrara Balloons Festival, the biggest italian Balloons Festival]] -->
A range of envelope sizes is available. The smallest, one-person, basket-less balloons (called "Hoppers" or "Cloudhoppers") have as little as 21,000&nbsp;ft³ (595&nbsp;m³) of envelope volume<ref name="LindstrandUK">{{cite web
| url = http://www.lindstrand.co.uk
| title = Lindstrand Hot Air Balloons: Cloudhopper
| accessdate = 2008-06-19}}</ref> (for a perfect sphere this would mean a radius of around ). At the other end of the scale are the balloons used by large commercial sightseeing operations that carry well over two dozen people and have envelope volumes of up to 600,000&nbsp;ft³ (16,990&nbsp;m³).<ref name="LindstrandUK"/> However, most balloons are roughly 100,000&nbsp;ft³ (2,832&nbsp;m³) and carry 3 to 5 people.

====Vents====
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. The most common type of vent is a disk-shaped flap of fabric called a ''parachute vent''. 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 completely open to collapse the balloon after landing.

An older, and today less commonly used, style of 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.

Some hot air balloons have ''turning vents'' which are side vents which, when opened, cause the balloon to rotate. Such vents are particularly useful for balloons with rectangular baskets in order to align the wider side of the basket for landing.

====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 cone. More-sophisticated designs attempt to minimize the circumferential 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 = What’s the Skinny on Racing Balloons?
| accessdate = 2008-05-05}}</ref> Finally, some specialized balloons are designed to minimize aerodynamic drag to improve flight performance in competitions.<ref>{{cite web
| url = http://balloonlife.com/2005/Aug-Sep05/racers.pdf
| title = Airship and Blimp Resources: Balloon Envelope Design
| accessdate = 2008-05-05}}</ref>

===Basket===
right|thumb|250px|A wicker basket capable of holding 16 passengers.
Baskets are commonly made of 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 twenty-four. Larger baskets often have internal partitions for structural bracing and to compartmentalize the passengers. Small holes may be woven into the side of the backet to act as foot holds for passengers climbing in or out.

Baskets may also be made of aluminum , especially a collapsable aluminum frame with a fabric skin, to reduce weight or increase portability. 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, and baskets that consist of little more than a seat for the pilot and perhaps one passenger.

===Burner===
thumb|left|A burner directing a flame into the envelope.
The burner unit gasifies liquid propane, mixes it with air, ignites the mixture, and directs the flame and exhaust into the mouth of the envelope. The unit may consist of one or more individual burners of which the pilot may use one or more at a time to generate the desired heat. Each burner is characterized by a metal coil of propane tubing through which the flame shoots in order to preheat the incoming liquid propane.

The burner unit may be suspended from the mouth of the envelope, or rigidly supported 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.

The pilot actuates a burner by opening a propane valve, called 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 piezo electric spark.<ref name="LindstrandFuel">{{cite web
| url = http://lindstrand.com/?id=14
| title = Lindstrand Fuel System: Burners & Tanks
| accessdate = 2007-03-05}}</ref>

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.

Burners can generate heat on the order of 30 million BTUs (31,651,677 kilojoule).<ref name="Sundance">{{cite web
| url = http://www.sundanceballoons.com/faqs.cfm#10
| title = Sundance Balloons Frequently Asked Questions
| accessdate = 2007-03-05}}</ref>

===Fuel tanks===
Propane fuel tanks are usually cylindrical pressure gauge. Common tank sizes are 10 (38), 15 (57), and 20 (76) US liters).<ref name="Cameron">{{cite web
| url = http://www.cameronballoons.com/tanks.html
| title = Cameron Balloons Fuel Tanks
| accessdate = 2007-03-07}}</ref> They may be intended for upright or horizontal use, and may be mounted inside or outside the basket.

thumb|right|Stainless steel fuel tanks, 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 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
| accessdate = 2007-11-13}}</ref> Warmed tanks will usually also be 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 rate of climb (vertical speed) indicator, 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 
| accessdate = 2006-12-26}}</ref> A 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
|-
| 100,000&nbsp;ft³ (2831.7&nbsp;m³) envelope
| align="right" |250
| align="right" |113.4
|-
| 5-passenger basket
| align="right" |140
| align="right" |63.5
|-
| double burner
| align="right" |50
| align="right" |22.7
|-
| 3 20-gallon (75.7-liter) fuel tanks full of propane
| align="right" |3 × 135 = 405
| align="right" |183.7
|-
| 5 passengers
| align="right" |5 × 150 = 750
| align="right" |340.2
|-
| '''sub total'''
| align="right" |1595
| align="right" |723.5
|-
| 100,000&nbsp;ft³ (2831.7&nbsp;m³) of heated air
| align="right" |5922
| align="right" |2686.2
|-
| '''total'''
| align="right" |(3.76&nbsp;tons) 7517
| align="right" |3409.7
|}
using a density of 0.9486&nbsp;kg/m³ for dry air heated to 210&nbsp;°F (99&nbsp;°C).

==Theory of operation ==
===Generating lift===
right|thumb|Thermal image showing temperature variation in a hot air balloon.
Raising the air temperature inside the envelope makes it lighter than the surrounding (ambient) air. The balloon floats because of the buoyant force exerted on it. This force is the same force acts on objects when they are in water and is described by 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 maximum 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
| title = DEPARTMENT OF TRANSPORTATION, FEDERAL AVIATION ADMINISTRATION, TYPE CERTIFICATE DATA SHEET NO. A33CE
| accessdate = 2008-06-16}}</ref>

It should be noted that the melting point of nylon is significantly higher than these maximum operating temperature — about 230&nbsp;°C (450&nbsp;°F). However the lower temperatures are generally used because the higher the temperature, the more quickly the strength of the nylon fabric degrades over time. With a maximum 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 below the maximum in order to extend the longevity of their envelope fabric.

The lift generated by 100,000&nbsp;ft³ (2831.7&nbsp;m³) of dry air heated to various temperatures may be calculated as follows: 
:{| class="wikitable"
|-
! air temperature
! air density
! air mass
! lift generated
|-
| 68 °F, 20 °C
| 1.2041 kg/m³
| 7517 lbs, 3409.7 kg
| 0 lbs, 0 kg
|-
| 210 °F, 99 °C
| 0.9486 kg/m³
| 5922 lbs, 2686.2 kg
| 1595 lbs, 723.5 kg
|-
| 250 °F, 120 °C
| 0.8978 kg/m³
| 5606 lbs, 2542.4 kg
| 1912 lbs, 867.3 kg
|}

The density of air at 68&nbsp;°F, 20&nbsp;°C is about 1.2&nbsp;kg/m³. The total lift for a balloon of 100,000&nbsp;ft³ heated to (210&nbsp;°F, 99&nbsp;°C) would be 1595&nbsp;lb, 723.5&nbsp;kg. 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 higher temperature, depending on the desired rate of climb. In reality, the air contained in the envelope is not all the same temperature, as the accompanying thermal image shows, and so these calculations are based on averages.