The theoretical fundamentals of aerostatics governing airship flight are revisited and presented in a simple manner. In the analysis it is assumed that the airship is flying in a standard atmosphere, and that both the atmospheric air and the gas inside the envelope of the airship are governed by a polytropic thermodynamic process. The equations formulated in this paper are used to solve some of the problems that were formulated in 1923 by the designers of a slide rule. The slide rule was used by the north-american pilots of the "Blimps" in the 1920s. The models presented in this paper should be considered not only to calculate the aerostatic equilibrium of the new generation airships, but al... More >