The invention relates to a mechanism to control the pitch and/or roll and/or center of gravity of a vehicle. The first embodiment is a track-based mass transfer system in which pathways are positioned along or radially terminate at a central horizontal plane of the vehicle to move one or more mass transfer devices to a desired location to control the pitch and/or roll and/or center of gravity of the vehicle. A second embodiment is a fluid mass distribution system in which one or more conduits selectively distribute a fluid to one or more tanks positioned near a central horizontal plane of the vehicle to control the pitch and/or roll and/or center of gravity of the vehicle.