Airships belong to the category of aerostat, which is an aircraft lighter than air that uses a buoyancy gas to generate its lift. It is classified into three main types—rigid airship, nonrigid airship, and hybrid airship—all of which can utilise two methods to increase or reduce (modu-late) the upward force to control it. The first way involves volume changing of gas and there-fore its density to balance the fuel weight decrease, manoeuvring the airship and changing its altitude. The second method is to use a hull aerodynamically to get a lift component, which can be modulated to change airship inclination, balance fuel, and reduce weight.