What is the purpose of a burner in a hot air balloon?

The function of a burner in a hot air balloon is integral to the operation of the balloon. It serves to fill the envelope, or the balloon part, with hot air. This is achieved by burning a mixture of propane and air, which heats the air inside the envelope. Since hot air is less dense than the cooler air outside, the heated air causes the balloon to rise. This principle of buoyancy is fundamental to how hot air balloons achieve lift.

While other functions may be important for the overall flight experience, they do not capture the primary reason for using a burner. For instance, controlling temperature is a secondary aspect of the burner's operation, as it directly influences the lift rather than simply serving as a temperature regulator. Similarly, the concepts of balancing or propelling the balloon forward are not functions attributed to the burner; hot air balloons do not generally have propulsion mechanisms, and their balance is managed through the distribution of weight rather than the burner itself.