(EN) The invention is a propulsion system for a lighter-than-air vehicle. In detail, the propulsion system includes a thrust producing assembly (26) rotatably mounted on the vehicle (10), about an axis of rotation in a plane at an acute angle to the vertical axis (14) of the vehicle, the assembly (26) rotatable in the plane from a position wherein the thrust axis of the assembly (26) is aligned with the longitudinal axis (12) to a position at least plus or minus ninety degrees thereto. A fuel efficient powerplant assembly (32A, 32B) mounted within the vehicle (10) having sufficient power for cruise conditions, and an output drive shaft (46) coupled to the thrust producing assembly (26). A light weight, high power powerplant assembly (71) is mounted directly to the thrust producing assembly (26) having sufficient power for docking conditions. A first clutch (39A, 39B) is provided for decoupling the fuel efficient powerplant (32A, 32B) from the thrust producing assembly (26) and second clutch means (73) is provided for de-coupling the powerplant (71) from the thrust producing assembly. An actuation system (74) is provided for rotating the thrust producing assembly about the axis of rotation.
