By filling out the gas
By type of filler airships are divided into:
Use the gas density is less than the density of the ambient air at equal temperature and pressure, which according to Archimedes' principle means that the airship would "swim" in the air. Nowadays it is usually an inert helium, despite its high cost, in the past used flammable hydrogen gas.
Thermal airships, using hot air.
Combination options (so-called type balloons Rozier). The idea of using hot air in this case is to regulate the buoyancy of the airship without the release of the carrier gas in the atmosphere - enough heat to stop the hot air after relief airship to heavier machine. Examples of these fairly rare designs can serve as a Termoplan and Research Airship Canopy-Glider.
Inside the airship can also be used for the transport of gaseous fuels. For example, one of the fundamental differences between the airship Graf Zeppelin from other zeppelins were used for the engines Blau gas, whose density was close to the air density and calorific value is much higher than that of gasoline. This allowed us to significantly increase the range and eliminates the need zatyazhelyat Airship as generation fuel (fuel consumption for motor Maybach is: petrol - 210 g and oil - 8 g per 1 hp.. / H, ie the engine to spend about 115 kg of gasoline per hour.)
Zatyazhelenie airships carried out through the issuance of the carrier gas, which created a series of economic and flight discomfort, in addition, the application of Blau gas led to lower than if you install many heavy tanks with gasoline, and a load on the skeleton. Blau gas was in the 12 compartments in the lower third of the frame airship, the amount which could be reduced to 30 000 m ³ (for hydrogen in this case left 105 000 m 000 m ³ -30 ³ = 75 000 m ³). Gasoline was taken on board as additional fuel.
Theoretically, there is also the possibility of the existence of vacuum airship, but in practice it is not feasible, and all projects of this unit remain speculative.