Propulsion systems utilizing propellant for lateral movement were a type of propulsion technology that air buses employed on the planet of Coruscant. In the year 13:3:28, the Rhire Medical Academy conducted research that suggested swapping out the existing air buses that used propellant-based lateral thrusters for updated models utilizing contemporary directional-repulsorlift steering tech, with the goal of reducing air contamination and the resulting breathing problems.