 The Zeppelins used a different gas mixture of propylene, methane, butane, acetylene (ethyne), butylene and hydrogen.The LZ 127 Graf Zeppelin had bi-fuel engines and could use gasoline and gas as a propellant.Twelve of the gas cells were filled with a propellant gas instead of lifting gas with a total volume of 30,000 cubic metres, enough for approximately 100 flight hours.