A propulsion system (10; 30) comprising: a plurality of power units (12A-N; 32A-N); a plurality of propulsors (14A-N; 34A-N), wherein respective power units of the plurality of power units are controllably mechanically or electrically coupled to the plurality of propulsors; and a controller (16; 36) configured to: receive a desired throttle value corresponding to a desired propulsive force; determine a number of power units of the plurality of power units to be coupled to the plurality of propulsors to achieve the desired propulsive force based on a respective power value associated with each respective power unit of the plurality of power units; and cause the number of power units of the plurality of power units to be coupled to the plurality of propulsors; characterized in that the controller is further configured to: determine a region of net thrust including the desired propulsive force, wherein the region comprises a decision region (130; 134) indicating that at least one additional power unit of the plurality of power units is necessary to achieve the desired propulsive force and a warning region (128; 132) indicating that the desired propulsive force is approaching the decision region; determine when net thrust enters the decision region; and cause the at least one additional power unit of the plurality of power units to be coupled to the plurality of propulsors responsive to the net thrust entering the decision region. a plurality of power units (12A-N; 32A-N); a plurality of propulsors (14A-N; 34A-N), wherein respective power units of the plurality of power units are controllably mechanically or electrically coupled to the plurality of propulsors; and a controller (16; 36) configured to: receive a desired throttle value corresponding to a desired propulsive force; determine a number of power units of the plurality of power units to be coupled to the plurality of propulsors to achieve the desired propulsive force based on a respective power value associated with each respective power unit of the plurality of power units; and cause the number of power units of the plurality of power units to be coupled to the plurality of propulsors; receive a desired throttle value corresponding to a desired propulsive force; determine a number of power units of the plurality of power units to be coupled to the plurality of propulsors to achieve the desired propulsive force based on a respective power value associated with each respective power unit of the plurality of power units; and cause the number of power units of the plurality of power units to be coupled to the plurality of propulsors; characterized in that the controller is further configured to: determine a region of net thrust including the desired propulsive force, wherein the region comprises a decision region (130; 134) indicating that at least one additional power unit of the plurality of power units is necessary to achieve the desired propulsive force and a warning region (128; 132) indicating that the desired propulsive force is approaching the decision region; determine when net thrust enters the decision region; and cause the at least one additional power unit of the plurality of power units to be coupled to the plurality of propulsors responsive to the net thrust entering the decision region. determine a region of net thrust including the desired propulsive force, wherein the region comprises a decision region (130; 134) indicating that at least one additional power unit of the plurality of power units is necessary to achieve the desired propulsive force and a warning region (128; 132) indicating that the desired propulsive force is approaching the decision region; determine when net thrust enters the decision region; and cause the at least one additional power unit of the plurality of power units to be coupled to the plurality of propulsors responsive to the net thrust entering the decision region. <EOS>