What is an Airship?

“An airship or dirigible is a type of aerostat or lighter-than-air aircraft that can be steered and propelled through the air using rudders and propellers or other thrust mechanisms. Unlike aircraft that use aerodynamics, such as fixed-wing aircraft and helicopters that produce lift by moving an airfoil through the air, aerostatic aircraft stay aloft by having a large “envelope” filled with a lifting gas that is less dense than the surrounding air. (Wikipedia)”