What are the principles of balloons and airships?

The working principle of airship is to change the buoyancy of atmosphere according to the volume of gas. F=pgV row, so it is a constant value in P and G. Therefore, according to V row, the volume of gas rises and falls, so the buoyancy of helium (less than air) increases, and the balloon of airship is inflated with gas storage tank, thus changing the displacement. So the principle of air ship is different from that of hot air balloon flight, because the density of hot air is smaller than that of cold air, and the same volume of hot air is lighter than that of cold air. By heating the air in the balloon to make it lighter and generate buoyancy, the balloon can be lifted off under load. By turning on the interval of the combustion switch, the temperature (gas density) of the balloon is adjusted to control the rise and fall of the hot air balloon; Use the wind direction of different height layers to control and adjust their own direction; A hot air balloon can't change its direction actively, and its flight speed is the same as the wind speed. So do airships and balloons.