In specific embodiments, a vehicle propellable through fluids or along surfaces, comprises a main work section and a plurality of propulsion units for propelling the main work section. The main work section supports one or more payloads. The propulsion units each include a rotor system and a ring-shaped wheel at least partially arranged about the rotor system and rotatable about the rotor system. The ring-shaped wheel is arranged at a banked angle relative to the rotor system.