11.   To compensate, propane burners are used to heat air in a compartment separate from the helium cell, providing extra lift.

12.   With a Rozier balloon, however, the heat from propane burners keeps the helium warm at night, eliminating or greatly reducing the need for ballast.

13.   For this trip, Branson plans to ride the jet stream with a helium balloon, with propane burners helping keep the gas expanded during darkness.

14.   Water is heated in metal buckets on propane burners.