When the weight of this is added to the weight of the aircraft structure, it adds up to the same weight as the air that the craft displaces. They are characterized by one or more large cells or canopies, filled with a relatively low-density gas such as helium, hydrogen, or hot air, which is less dense than the surrounding air.
Main article: Aerostat Hot air balloons Airship USS Akron over Manhattan in the 1930sĪerostats use buoyancy to float in the air in much the same way that ships float on the water.
