A deployable fairing for a transport vehicle, comprising: an enclosure (122, 1122) formed from flexible sheeting (124, 1124) and forming an outer surface (130, 1130); the enclosure being adapted to be internally pressurized; a structural frame (120, 1120) comprising a plurality of rigid structural members (140, 142, 144, 146, 148, 150, 152, 154, 156, 168, 162, 164, 166, 168, 1140, 1142, 1144, 1146, 1148, 1150, 1154, 1162); the structural frame comprising at least two subframes; the subframes being pivotally coupled to one another so that the structural frame is foldably movable between a collapsed configuration and an expanded configuration; the enclosure being supported by and coupled to the structural frame so that the enclosure moves with the structural frame and unfolds when the structural frame moves from the collapsed configuration to the expanded configuration and folds in upon itself when the structural frame moves from the expanded configuration to the collapsed configuration; wherein: movement of the structural frame from the collapsed configuration to the expanded configuration develops tension on at least a portion of the outer surface of the enclosure; and movement of the structural frame from the expanded configuration to the collapsed configuration releases the tension; characterized in that: an actuator (176,1176) acts between the subframes and is adapted to move the structural frame between the expanded configuration and the collapsed configuration, and when the enclosure is internally pressurized while the structural frame is in the expanded configuration, the outer surface of the enclosure is structurally stiff and conforms to a predefined aerodynamic shape. an enclosure (122, 1122) formed from flexible sheeting (124, 1124) and forming an outer surface (130, 1130); the enclosure being adapted to be internally pressurized; a structural frame (120, 1120) comprising a plurality of rigid structural members (140, 142, 144, 146, 148, 150, 152, 154, 156, 168, 162, 164, 166, 168, 1140, 1142, 1144, 1146, 1148, 1150, 1154, 1162); the structural frame comprising at least two subframes; the subframes being pivotally coupled to one another so that the structural frame is foldably movable between a collapsed configuration and an expanded configuration; the enclosure being supported by and coupled to the structural frame so that the enclosure moves with the structural frame and unfolds when the structural frame moves from the collapsed configuration to the expanded configuration and folds in upon itself when the structural frame moves from the expanded configuration to the collapsed configuration; wherein: movement of the structural frame from the collapsed configuration to the expanded configuration develops tension on at least a portion of the outer surface of the enclosure; and movement of the structural frame from the expanded configuration to the collapsed configuration releases the tension; movement of the structural frame from the collapsed configuration to the expanded configuration develops tension on at least a portion of the outer surface of the enclosure; and movement of the structural frame from the expanded configuration to the collapsed configuration releases the tension; characterized in that: an actuator (176,1176) acts between the subframes and is adapted to move the structural frame between the expanded configuration and the collapsed configuration, and when the enclosure is internally pressurized while the structural frame is in the expanded configuration, the outer surface of the enclosure is structurally stiff and conforms to a predefined aerodynamic shape. an actuator (176,1176) acts between the subframes and is adapted to move the structural frame between the expanded configuration and the collapsed configuration, and when the enclosure is internally pressurized while the structural frame is in the expanded configuration, the outer surface of the enclosure is structurally stiff and conforms to a predefined aerodynamic shape.