The invention is a propulsion system for a lighter-than-air vehicle, the vehicle having a longitudinal, lateral and vertical axis. In detail, the propulsion system includes a thrust producing assembly rotatably mounted on the vehicle, the assembly rotatable about an axis of rotation in a plane at an acute angle to the vertical axis of the vehicle, the assembly rotatable in the plane from a position wherein the thrust axis of the assembly is aligned with the longitudinal axis to a position at least plus or minus ninety degrees thereto. A powerplant assembly is coupled to the thrust producing assembly to provide power thereto. The powerplant assembly includes a fuel efficient powerplant assembly mounted within the vehicle having sufficient power for cruise conditions, the fuel efficient powerplant having a output drive shaft coupled to the thrust producing assembly. A light weight, high power powerplant assembly is mounted directly to the thrust producing assembly having sufficient power for docking conditions. A first clutch is provided for de-coupling the fuel efficient powerplant from the thrust producing assembly and a second clutch means for decoupling the light weight, high power powerplant from the thrust producing assembly. An actuation system is provided for rotating the thrust producing assembly about the axis of rotation.