The Study on Working Fluid for Cold Gas Reaction Control System and Its Expansion Time in Regulated and Non-regulated Conditions

The trajectory of a launch vehicle is controlled using roll, pitch and yaw manoeuvers. While using a single engine, pitch and yaw control is achieved through engine gimbal, whereas additional methods are required to create roll moment for the vehicle (Sutton and Biblarz in Rocket propulsion element [1]). In the current study, different methods of creating roll moment for a launch vehicle are assessed using cold gas-based reaction control system. After a comparison between helium, methane and nitrogen, it is found that nitrogen gas is the most suitable working fluid for the system considering performance aspects. Also, the operating characteristics of a gaseous nitrogen-based system under regulated and non-regulated mode are studied in detail and compared.