She was always the unique one with her SILTS(Shuttle Infrared Lee-side Temperature Sensing) pod on her vertical tail and the black wing chines. The propellants ignite on contact, so theoretically the OMS engines could get ignited as often as desired, but the number of restarts were limited by the supply of N 2 used for operating the valves and purging the fuel lines of the engines, which was only enough for ten restarts.ĭifferences between the orbiters Columbia Ĭolumbia (OV-102) was the first space-rated orbiter and was always the heaviest of the fleet. OMS engine were the bipropellant valve assembly, the injector plate, the thrust chamber, and the nozzle. In the OMS engine, fuel was burned with oxidizer to produce thrust. The OMS engine would not have propellant pumps propellant flow to theĮngines was maintained by pressurizing the propellant tanks with helium.
Throughout the OMS pods to prevent any freezing of propellants during long periods inĮach OMS engine had a gaseous nitrogen tank that would provided pressurized nitrogen to operate the engine valves. Temperatures normally experienced during a mission, however, electrical heaters wre located These propellants are hypergolic, which means that they ignite when they come in contact withĮach other therefore, no ignition device is needed. The OMS engines used monomethyl hydrazine as the fuel and nitrogen tetroxide as the oxidizer.
The minimum duration of an OMS engine firing wass 2 seconds. Each OMS engines were capable of 1,000 starts and 15 hours of cumulative firing. The velocity change required for orbital adjustment is approximately 2 ft/sec (0.61 m/s) for each nautical mile of altitude change. Orbital insertion burns and deorbit burns each typically required a velocity change of about 100–500 ft/sec. Using up a fully loaded tank, the OMS could provide a total velocity change of approximately 1,000 ft/sec (304.8 m/s). For a typical orbiter weight, both engines together would create an acceleration of approximately 2 ft/sec 2 or 0.06 g’s. However, during a one-OMS-engine burn, RCS roll control was required.Įach of the two OMS engines produced 6,000 pounds of thrust (26.7 kN). During a two-OMS-engine burn, the RCS would come into operation only if the attitude orĪttitude rate limits are exceeded. The OMS engines could be used singularly by directing the thrust vector through the orbiter center of gravity or together by directing the thrust vector of both engines parallel to the X axis.
Dps velocity editing manual#
This gimbal system provided for vehicle steering during OMS burns by controlling the direction of the engine thrust in pitch and yaw (thrust vector control) in response to commands from the digital autopilot or from the manual controls. The engines were located in gimbal mounts that allow the engine to pivot left and right and up and down under the control of two electromechanical actuators. The OMS engines were designated left and right, descriptive of location. The pods were removable to facilitate orbiter turnaround, The OMS/RCS pods were designed to be reused for up to 100 missions with only minor repair, Power was supplied to the OMS through main buses, control buses, and alternating currentīuses for the operation of switches, valves, instrumentation, gimbal actuators, and heaters. The OMS valves and gimbal actuators received commands, and the system returned someĭata to the general purpose computers through multiplexer/demultiplexer units. The OMS had important interfaces with the data processing system and the electrical power Propellant from one pod could be fed to theĮngine in the other pod through crossfeed lines that connected the left and right OMS pods. For velocityĬhanges greater than 6 fps, a single OMS engine burn was preferred, because engine lifetimeĬoncerns make it desirable to minimize engine starts. For velocity changes less than 6 fps (2 m/s), RCS was used. Normally, OMS maneuvers wereĭone using both OMS engines together however, a burn could be performed using only Which also housed the aft reaction control system (RCS), are referred to as the OMS/RCS pods.Įach pod contained one OMS engine and the hardware needed to pressurize, store, andĭistribute the propellants to perform OMS engine burns. The OMS was housed in two independent pods on each side of the orbiter’s aft fuselage. Amounts available for interconnect depend on loading and number of OMS starts during the mission. Each OMS pod could provide more than 1,000 pounds of propellant to the RCS. The OMS may be used to provide thrust above 70,000 feet altitude. The OMS wass used for orbit insertion, orbit circularization, orbit transfer, rendezvous, and deorbit. The OMS would provide propulsion for the orbiter during the orbit phase of flight.