The driving force of hotair balloons is the burner below the envelope
Hot-air balloon burner with two burners - SAFIRE™ - Cameron Balloons US - with three burners / with four burners
Hot-air balloon burner with one burner - POWERPLUS SPORT - Ultramagic
Balloon flight - Hot-air ballooning | Britannica
Hot Air Balloon Burners Stock Photo | Royalty-Free | FreeImages
Hot air balloon burner heating up the air in the balloon envelope
Burners - Ultramagic
Gas Burner Filling Hot Air Balloons In The Early Morning" by Stocksy Contributor "Marilar Irastorza" - Stocksy
Hot Air Balloon Being Inflated In Preparation For Flight Gas Burner Fills The Canopy Of A Balloon With Hot Air Pumping The Fire To Apply Hot Air Into Fireproof Airballoon Stock Photo -