🎈 Airship: Helium Lift, Standard Atmosphere, Pressure Height and Ceiling (2D)

Side view of a helium airship rising through the standard atmosphere, with its gas bag expanding until the hull is full and the lift falling as the air thins. Set hull volume, structure and payload mass, helium fill, helium purity, a hot or cold day and gas superheat, and see the gross lift, the pressure height, the static ceiling and how much payload the ship can take. The atmosphere, Archimedes lift, pressure height and ceiling are checked numerically, with four in-page numerical checks.