Reactive control system ( Eng. Reaction Control System, RCS ) - a system of orientation engines, installed on the Space Shuttle orbiters and designed to accurately control the spatial position of the ship and perform maneuvers in outer space.
The system consists of a set of small rocket engines, which are divided into front and rear rows. The front row is located in the nose of the fuselage of the device and consists of 14 main and 2 vernier engines, and the rear in two OMS / RCS blocks on the rear, together with the engines of the orbital maneuvering system and consists of 12 main and 2 vernier engines on each OMS / block RCS Engines of the reactive control system operate on a self-igniting pair of monomethylhydrazine / nitrogen tetraoxide . Fuel and oxidizing agent are fed into the combustion chamber under the action of the pressure of gaseous helium supplied from two helium tanks.
The main engines are designed for approximately 100 flights and are able to withstand almost 20,000 starts and 12,800 seconds of total operating time, the thrust of one engine is 387 N in vacuum, the ratio of oxidizer to fuel can be from 1.6 to 1, the pressure in the combustion chamber 10, 48 bar. They can operate in stable thrust from one to 150 seconds maximum, while continuous operation during one flight can be 800 seconds maximum for the rear row of RCS with X-engines, and a maximum of 300 seconds for the front row of RCS without X- engines, as well as in a pulsed mode with a minimum thrust impulse time of 0.08 seconds, above 38.1 km above the Earth's surface. A large number of main engines provides sufficient redundancy. The expansion ratio of the main RCS engines varies from 22: 1 to 30: 1.
Reuse of vernier engines depends on the life of the combustion chambers. They are able to withstand 330,000 starts and 12,800 seconds of total operating time. Vernier engines can operate in maximum stable traction from one to 125 seconds maximum, as well as in pulse mode with a minimum traction pulse time of 0.08 seconds. Vernier engines are used for fine control of the position of the ship and for long-term stabilization of the spatial position. Their degree of expansion varies from 20: 1 to 50: 1. Vernier engines are not duplicated.