The Orbital Maneuvering System, which is made up of two Orbital Maneuvering System engines and all of their related hardware. One Orbital Maneuvering System engine is housed in each of two Orbital Maneuvering System (OMS)/Reaction Control System (RCS) pods attached to the top aft end of the Orbiter.
The system consist of hypergolic liquid-propellant rocket engines used on the Space Shuttle. Designed and manufactured in the United States by Aerojet, the system was used during launch to produce supplementary thrust and on-orbit to provide orbital injection, orbital correction and the spacecraft's deorbit burn.[2] The OMS pods contains a single AJ10-190 engine, based on the Apollo Service Module's Service Propulsion System engine,[citation needed] which produces 26.7 kilonewtons (6,000 lbf) of thrust with a specific impulse (Isp) of 316 seconds.[3] Each engine could be reused for 100 missions and was capable of a total of 1,000 starts and 15 hours of burn time.
These pods also contained the Orbiter's aft set of reaction control system (RCS) engines, and so were referred to as OMS/RCS pods. The OM engine and RCS systems both burned monomethylhydrazine (MMH) as fuel, which was oxidized with dinitrogen tetroxide (N2O4), with the propellants being stored in tanks within the OMS/RCS pod, alongside other fuel and engine management systems. When full, the pods together carried around 8,174 kilograms (18,021 lb) of MMH and 13,486 kilograms (29,732 lb) of N2O4, allowing the OMS to produce a total of around 1,000 feet per second (300 m/s) of delta-v with a 65,000-pound (29,500 kg) payload.
The Reaction Control System, which is made up of thrusters fired to help the Orbiter achieve a precise orbital path or perform changes in its position, and all of their related hardware. Thrusters are located at the forward end of the Orbiter and in each of the two aft Orbital Maneuvering System (OMS)/Reaction Control System (RCS) pods.
The RCS contains a total of 38 primary thrusters and 6 vernier thrusters. The forward RCS array contains 14 primary thrusters and two vernier thrusters. A total of 12 primary thrusters and two vernier thrusters are housed in each of the two OMS/RCS pods. Below are a few reference images of the main engine with her OMS/RCS pods.
Each RCS thruster burns a combination of monomethyl hydrazine and nitrogen tetroxide liquid fuel. Each primary thruster can produce a thrust of 870 pounds, while each vernier thruster can produce a thrust of 24 pounds. The RCS thrusters can be fired in a plethora of combinations depending on the specific mission requirements.
More after the jump.
The Aerojet Rocketdyne RS-25, otherwise known as the Space Shuttle Main Engine (SSME), is a liquid-fuel cryogenic rocket engine that was used on NASA's Space Shuttle and is planned to be used on its successor, the Space Launch System. Built in the United States by Rocketdyne, the RS-25 burns cryogenic liquid hydrogen & liquid oxygen propellants, with each engine producing 1,859 kN (418,000 lbf) of thrust at liftoff. Although the RS-25 can trace its heritage back to the 1960s, concerted development of the engine began in the 1970s, with the first flight, STS-1, occurring on April 12, 1981. The RS-25 has undergone several upgrades over its operational history to improve the engine's reliability, safety and maintenance load.
The engine produces a specific impulse (Isp) of 452 seconds (4.43 km/s) in a vacuum, or 366 seconds (3.59 km/s) at sea level, has a mass of approximately 3.5 tonnes (7,700 pounds), and is capable of throttling between 67% and 109% of its rated power level in one-percent increments. The RS-25 operates under temperatures ranging from −253 °C (−423 °F) to 3,315 °C (6,000 °F).
On the Space Shuttle, the RS-25 was used in clusters of three engines mounted in the aft structure of the Orbiter, with fuel being drawn from the external tank. The engines were used for propulsion during the entirety of the spacecraft's ascent, with additional thrust being provided by two solid rocket boosters and the orbiter's two AJ-10-190 Orbital Maneuvering System engines. Following each flight, the engines were removed from the orbiter, inspected and refurbished before being reused on another mission.
Both the Revell and Monogram 1/72 kit provided a very poor representation of the Shuttle's main engines, and mere decals for her rear OMS/RCS propulsion units. You will definitely need to replace these since at 1/72 scale, your orbiter is big enough for people to scrutinize. All of these can be detailed using good after market parts.
Fisher Model & Pattern
I chanced upon this site during my research for good aftermarket parts and actually found a fantastic set that provided for a complete rear section overhaul. Do check out Fisher Model & Pattern's Space Shuttle Rocket Upgrade set in 1/72 (Kit No. SCA001). The set comprises of three highly detailed main engine bells, two CMS nozzles and two very detailed OMS/RCS rack which fits both the Monogram and Revell kits.
I have to specially thank Paul Fisher for this complimentary set. It reached me within 2 weeks, which was quite fast considering I live like on the other side of the globe, and they were so securely packed the set came to me in mint condition. The actual box packaging isn't very big but they were adequate enough to contain and protect the parts.
There were some papers packed in between inside to prevent the parts from moving too much during the transit. And I was excited to see everything neatly packed inside a zip lock bag, with the main engine bells neatly wrapped in near translucent paper.
When I took the parts out for a closer inspection, I was very impressed with the level of quality with the casting. The details were solid and clearly represented with each parts and they were superbly cast. There were literally no flash or holes found in any of them. And there are only a few GK makers and after market providers who deliver such quality. I am including Fisher Model & Pattern into that list.
Not only were the parts accurately represented here in 1/72 scale, but the finer details were excellently captured as well. Just check out the fine details on the OMS/RCS rack. Some surgery will be required to install this piece.
You can also see for yourself the quality of the main engine bell and CMS nozzles below. The parts were smooth to the touch with no coarse sections.
And here is where Fisher Models & Pattern's upgrade set is set apart from the other aftermarket sets. Inside the main engine bell, you can see soft lining strips contouring along the curve of the bell. Others have them as smooth and bare. Though those are not wrong as you can see from the reference image below, but the details with this set would provide for more things to see.
The set retails at USD $49.95 and it is worth buying since you're getting an extensive replacement set for the rear section of the shuttle. My set didn't come with any instruction sheet but you don't really need one since it is very clear how and where the parts fit.
In conclusion, if you are an ardent shuttle enthusiast like me who was looking for a good engine replacement set, I'd recommend getting this one. And looking at the quality of the set, it is worth taking a look at Fisher Model's website as well since he has an extensive array of other accessory and conversion sets encompassing a lot of World War II subjects (planes) and racing cars.
Fisher Model & Pattern
I chanced upon this site during my research for good aftermarket parts and actually found a fantastic set that provided for a complete rear section overhaul. Do check out Fisher Model & Pattern's Space Shuttle Rocket Upgrade set in 1/72 (Kit No. SCA001). The set comprises of three highly detailed main engine bells, two CMS nozzles and two very detailed OMS/RCS rack which fits both the Monogram and Revell kits.
There were some papers packed in between inside to prevent the parts from moving too much during the transit. And I was excited to see everything neatly packed inside a zip lock bag, with the main engine bells neatly wrapped in near translucent paper.
When I took the parts out for a closer inspection, I was very impressed with the level of quality with the casting. The details were solid and clearly represented with each parts and they were superbly cast. There were literally no flash or holes found in any of them. And there are only a few GK makers and after market providers who deliver such quality. I am including Fisher Model & Pattern into that list.
Not only were the parts accurately represented here in 1/72 scale, but the finer details were excellently captured as well. Just check out the fine details on the OMS/RCS rack. Some surgery will be required to install this piece.
You can also see for yourself the quality of the main engine bell and CMS nozzles below. The parts were smooth to the touch with no coarse sections.
And here is where Fisher Models & Pattern's upgrade set is set apart from the other aftermarket sets. Inside the main engine bell, you can see soft lining strips contouring along the curve of the bell. Others have them as smooth and bare. Though those are not wrong as you can see from the reference image below, but the details with this set would provide for more things to see.
The set retails at USD $49.95 and it is worth buying since you're getting an extensive replacement set for the rear section of the shuttle. My set didn't come with any instruction sheet but you don't really need one since it is very clear how and where the parts fit.
In conclusion, if you are an ardent shuttle enthusiast like me who was looking for a good engine replacement set, I'd recommend getting this one. And looking at the quality of the set, it is worth taking a look at Fisher Model's website as well since he has an extensive array of other accessory and conversion sets encompassing a lot of World War II subjects (planes) and racing cars.
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