Techniques involve an air flow assembly to provide pressurized air, e.g., for use by an air-cushion vehicle (ACV) or other craft. The air flow assembly includes a volute having a central chamber, a lift duct, and a thruster duct. The air flow assembly further includes a set of guide members disposed between the central chamber and the thruster duct, and linkage coupled to the set of guide members. The linkage is constructed and arranged to transition the set of guide members between a closed configuration in which the set of guide members closes an opening between the central chamber and the thruster duct, and an opened configuration in which the set of guide members opens the opening between the central chamber and the thruster duct.