With a small amount of additional heat the balloon will reach equilibrium. Typically inflation takes 15 to 20 minutes. To launch and fly a balloon safely requires a minimum crew of three people plus pilot. Duties of the crew typically include preparing for the launch, following the balloon in the chase vehicle, obtaining permission of the landowner for the balloon landing and retrieval, keeping spectators out of the landing area, and ensuring that gates are left as the are found and that property is not damaged. Once inflated the balloon will weigh about 2.5 tons including the weight of the air in the envelope.
Liquid propane is used to heat hot air balloons.
Propane is a stable and predictable fuel although it is also extremely flammable. It is carried in liquid form, under pressure, in 10 to 20 gallon stainless steel fuel tanks and supplied to the burner through flexible hoses. The burner flame will shoot up approximately 10 to 15 feet in a blast that is controlled by the pilot. The typical 90 minute flight will use about 20 gallons of propane. Many balloons have redundant fuel and burner systems for added safety.