Space Shuttle Main Engine cluster The Space Shuttle Main Engines (SSMEs) are the three main engines on the Space Shuttle orbiter. They are constructed by Pratt & Whitney's Rocketdyne Division. The SSME is also designated as the RS-24 for engineering purposes. Download high resolution version (1752x2617, 850 KB)Space shuttle main engine block This article contains material and/or images that originally came from a NASA website. ...
Download high resolution version (1752x2617, 850 KB)Space shuttle main engine block This article contains material and/or images that originally came from a NASA website. ...
For the current mission, see STS-118 NASAs Space Shuttle, officially called Space Transportation System (STS), is the United States governments current manned launch vehicle. ...
Pratt & Whitney is an American aircraft engine manufacturer whose products are widely used in both civil and military aircraft. ...
F-1 rocket engine Rocketdyne is a United States company that designs and produces rocket engines that use liquid propellants. ...
Introduction The Space Shuttle main engines are very sophisticated power plants that burn liquid hydrogen and liquid oxygen from the Space Shuttle external tank. They are used for propulsion during its ascent, in addition to the two more powerful Solid Rocket Boosters and sometimes the Orbital Maneuvering System. Each engine can generate almost 1.8 MN (400,000 pounds) of thrust at liftoff. The engines are capable of generating a specific impulse (Isp) of 453 seconds in a vacuum, or 363 seconds at sea level (exhaust velocities of 4440 m/s and 3560 m/s respectively). Overall, a space shuttle main engine weighs approximately 3.2 t (7,000 pounds). The engines are removed after every flight and taken to the Space Shuttle Main Engine Processing Facility (SSMEPF) for inspection and replacement of any necessary components. This article does not adequately cite its references or sources. ...
This article does not cite any references or sources. ...
The Space Shuttle External Tank (ET) on its way to the Vehicle Assembly Building. ...
The Space Shuttle Solid Rocket Booster (SRB) is the rocket that provides 83% of liftoff thrust for the Space Shuttle. ...
An OMS pod detached from a Shuttle for maintenance. ...
The pound-force is a non-SI unit of force or weight (properly abbreviated lbf or lbf). The pound-force is equal to a mass of one pound multiplied by the standard acceleration due to gravity on Earth (which is defined as exactly 9. ...
Thrust is a reaction force described quantitatively by Newtons Second and Third Laws. ...
Specific impulse (usually abbreviated Isp) is a way to describe the efficiency of rocket and jet engines. ...
The specific impulse (commonly abbreviated Isp) of a propulsion system is the impulse (change in momentum) per unit of propellant. ...
The Space Shuttle's rocket engines are capable of operating at extreme temperatures. The liquid hydrogen fuel is stored at −253 degrees Celsius (−423 degrees Fahrenheit). However, when burned with liquid oxygen, the temperature in the combustion chamber reaches 3,300 °C (6,000 °F), higher than the boiling point of iron. If the main engines pumped water instead of liquid oxygen and liquid hydrogen, an average family-sized swimming pool could be drained in 25 seconds. A cold (un-ignited) rocket engine test at NASA A rocket engine is a reaction engine that can be used for spacecraft propulsion as well as terrestrial uses, such as missiles. ...
Celsius is, or relates to, the Celsius temperature scale (previously known as the centigrade scale). ...
Fahrenheit is a temperature scale named after the German-Dutch physicist Daniel Gabriel Fahrenheit (1686–1736), who proposed it in 1724. ...
Italic text This article is about the boiling point of liquids. ...
General Name, Symbol, Number iron, Fe, 26 Chemical series transition metals Group, Period, Block 8, 4, d Appearance lustrous metallic with a grayish tinge Standard atomic weight 55. ...
This article needs additional references or sources for verification. ...
Apart from the three main engines, the orbiter has 44 smaller rockets around the orbiter's surface, which are part of the Orbital Maneuvering System and Reaction Control System, used to provide steering, pointing, and altitude adjustment capability while in orbit. An OMS pod detached from a Shuttle for maintenance. ...
A reaction control system (abbreviated RCS) is a subsystem of a spacecraft. ...
The engines perform as follows: Fuel and oxidizer from the external tank enters the orbiter at the orbiter/external tank umbilical disconnect and then the orbiter's main propulsion system feed lines. There the fuel and oxidizer each branch out into three parallel paths, to each engine. In each branch, prevalves must be opened to permit flow to the low-pressure fuel or oxidizer turbopump. Fuel imports in 2005 Fuel is any material that is capable of releasing energy when its chemical or physical structure is altered. ...
An oxidizing agent is a substance that oxidizes another substance in electrochemistry or redox chemical reactions in general. ...
The introduction to this article provides insufficient context for those unfamiliar with the subject matter. ...
A turbopump can refer to either of two types of pump. ...
Oxidizer system
Major components of the Space Shuttle main engine The Low Pressure Oxidizer Turbopump (LPOTP) is an axial-flow pump driven by a six-stage turbine powered by liquid oxygen. It boosts the liquid oxygen's pressure from 0.7 to 2.9 MPa (100 to 422 psia). The flow from the LPOTP is supplied to the High-Pressure Oxidizer Turbopump (HPOTP). During engine operation, the pressure boost permits the High Pressure Oxidizer Turbine to operate at high speeds without cavitating. The LPOTP operates at approximately 5,150 rpm. The LPOTP, which is approximately 450 by 450 mm (18 by 18 inches) , is connected to the vehicle propellant ducting and supported in a fixed position by the orbiter structure. Image File history File links Size of this preview: 700 × 600 pixelsFull resolution (718 × 615 pixel, file size: 117 KB, MIME type: image/png) BOOSTER SYSTEMS BRIEFS JSC-19041 File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ...
Image File history File links Size of this preview: 700 × 600 pixelsFull resolution (718 × 615 pixel, file size: 117 KB, MIME type: image/png) BOOSTER SYSTEMS BRIEFS JSC-19041 File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ...
A Siemens steam turbine with the case opened. ...
A pressure gauge reading in PSI (red scale) and kPa (black scale) The pound-force per square inch (symbol: lbf/in²) is a non-SI unit of pressure based on avoirdupois units. ...
This article or section does not cite any references or sources. ...
rpm or RPM may mean: revolutions per minute RPM Package Manager (originally called Red Hat Package Manager) RPM (movie) RPM (band), a Brazilian rock band RPM (magazine), a former Canadian music industry magazine In firearms, Rounds Per Minute: how many shots an automatic weapon can fire in one minute On...
An inch (plural: inches; symbol or abbreviation: in or, sometimes, ″ - a double prime) is the name of a unit of length in a number of different systems, including English units, Imperial units, and United States customary units. ...
The HPOTP consists of two single-stage centrifugal pumps (a main pump and a preburner pump) mounted on a common shaft and driven by a two-stage, hot-gas turbine. The main pump boosts the liquid oxygen's pressure from 2.9 to 30 MPa (422 to 4,300 psi) while operating at approximately 28,120 rpm. The HPOTP discharge flow splits into several paths, one of which is routed to drive the LPOTP turbine. Another path is routed to and through the main oxidizer valve and enters into the main combustion chamber. Another small flow path is tapped off and sent to the oxidizer heat exchanger. The liquid oxygen flows through an anti-flood valve that prevents it from entering the heat exchanger until sufficient heat is present to convert the liquid oxygen to gas. The heat exchanger utilizes the heat contained in the discharge gases from the HPOTP turbine to convert the liquid oxygen to gas. The gas is sent to a manifold and is then routed to the external tank to pressurize the liquid oxygen tank. Another path enters the HPOT second-stage preburner pump to boost the liquid oxygen's pressure from 30 to 51 MPa (4,300 psia to 7,420 psia). It passes through the oxidizer preburner oxidizer valve into the oxidizer preburner and through the fuel preburner oxidizer valve into the fuel preburner. The HPOTP is approximately 600 by 900 mm (24 by 36 inches). It is attached by flanges to the hot-gas manifold. A pressure gauge reading in PSI (red scale) and kPa (black scale) The pound-force per square inch (symbol: lbf/in²) is a non-SI unit of pressure based on avoirdupois units. ...
These water valves are regulated by handles. ...
A combustion reaction taking place in a igniting match Combustion or burning is a complex sequence of exothermic chemical reactions between a fuel and an oxidant accompanied by the production of heat or both heat and light in the form of either a glow or flames. ...
A heat exchanger is a device built for efficient heat transfer from one fluid to another, whether the fluids are separated by a solid wall so that they never mix, or the fluids are directly contacted. ...
The HPOTP turbine and HPOTP pumps are mounted on a common shaft. Mixing of the fuel-rich hot gas in the turbine section and the liquid oxygen in the main pump could create a hazard. To prevent this, the two sections are separated by a cavity that is continuously purged by the MPS engine helium supply during engine operation. Two seals minimize leakage into the cavity. One seal is located between the turbine section and the cavity, and the other is between the pump section and cavity. Loss of helium pressure in this cavity results in an automatic engine shutdown.
Hydrogen fuel system
Orbiter main propulsion system Fuel enters the orbiter at the liquid hydrogen feed line disconnect valve, then flows into the orbiter liquid hydrogen feed line manifold and branches out into three parallel paths to each engine. In each liquid hydrogen branch, a prevalve permits liquid hydrogen to flow to the low-pressure fuel turbopump when the prevalve is open. Image File history File links No higher resolution available. ...
Image File history File links No higher resolution available. ...
Fuel imports in 2005 Fuel is any material that is capable of releasing energy when its chemical or physical structure is altered. ...
The Low Pressure Fuel Turbopump (LPFTP) is an axial-flow pump driven by a two-stage turbine powered by gaseous hydrogen. It boosts the pressure of the liquid hydrogen from 30 to 276 psia (0.2 to 1.9 MPa) and supplies it to the High-Pressure Fuel Turbopump (HPFTP). During engine operation, the pressure boost provided by the LPFTP permits the HPFTP to operate at high speeds without cavitating. The LPFTP operates at approximately 16,185 rpm. The LPFTP is approximately 450 by 600 mm (18 by 24 inches). It is connected to the vehicle propellant ducting and is supported in a fixed position by the orbiter structure 180 degrees from the LPOTP.
The HPFTP is a three-stage centrifugal pump driven by a two-stage, hot-gas turbine. It boosts the pressure of the liquid hydrogen from 1.9 to 45 MPa (276 to 6,515 psia). The HPFTP operates at approximately 35,360 rpm. The discharge flow from the turbopump is routed to and through the main valve and then splits into three flow paths. One path is through the jacket of the main combustion chamber, where the hydrogen is used to cool the chamber walls. It is then routed from the main combustion chamber to the LPFTP, where it is used to drive the LPFTP turbine. A small portion of the flow from the LPFTP is then directed to a common manifold from all three engines to form a single path to the external tank to maintain liquid hydrogen tank pressurization. The remaining hydrogen passes between the inner and outer walls to cool the hot-gas manifold and is discharged into the main combustion chamber. The second hydrogen flow path from the main fuel valve is through the engine nozzle (to cool the nozzle). It then joins the third flow path from the chamber coolant valve. The combined flow is then directed to the fuel and oxidizer preburners. The HPFTP is approximately 550 by 1100 mm (22 by 44 inches). It is attached by flanges to the hot-gas manifold.
Pre-burners and thrust control system
Main Engine #1 being installed into an orbiter in one of the Orbiter Processing Facilities (OPF) The oxidizer and fuel preburners are welded to the hot-gas manifold. The fuel and oxidizer enter the preburners and are mixed so that efficient combustion can occur. The augmented sparkigniter is a small combination chamber located in the center of the injector of each preburner. The two dual-redundant spark igniters, which are activated by the engine controller, are used during the engine start sequence to initiate combustion in each preburner. They are turned off after approximately three seconds because the combustion process is then self-sustaining. The preburners produce the fuel-rich hot gas that passes through the turbines to generate the power to operate the high-pressure turbopumps. The oxidizer preburner's outflow drives a turbine that is connected to the HPOTP and the oxidizer preburner pump. The fuel preburner's outflow drives a turbine that is connected to the HPFTP. Download high resolution version (1050x689, 252 KB)Space shuttle main engines undergoing overhaul File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ...
Download high resolution version (1050x689, 252 KB)Space shuttle main engines undergoing overhaul File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ...
Welding is a joining process that produces coalescence of materials (typically metals or thermoplastics) by heating them to welding temperature, with or without the application of pressure or by the application of pressure alone, and with or without the use of filler material. ...
This article does not cite any references or sources. ...
Look up manifold in Wiktionary, the free dictionary. ...
Look up Spark in Wiktionary, the free dictionary. ...
The speed of the HPOTP and HPFTP turbines depends on the position of the corresponding oxidizer and fuel preburner oxidizer valves. These valves are positioned by the engine controller, which uses them to throttle the flow of liquid oxygen to the preburners and, thus, control engine thrust. The oxidizer and fuel preburner oxidizer valves increase or decrease the liquid oxygen flow, thus increasing or decreasing preburner chamber pressure, HPOTP and HPFTP turbine speed, and liquid oxygen and gaseous hydrogen flow into the main combustion chamber, which increases or decreases engine thrust, thus throttling the engine. The oxidizer and fuel preburner valves operate together to throttle the engine and maintain a constant 6-1 propellant mixture ratio.
The main oxidizer valve and the main fuel valve control the flow of liquid oxygen and liquid hydrogen into the engine and are controlled by each engine controller. When an engine is operating, the main valves are fully open.
Cooling control system A coolant control valve is mounted on the combustion chamber coolant bypass duct of each engine. The engine controller regulates the amount of gaseous hydrogen allowed to bypass the nozzle coolant loop, thus controlling its temperature. The chamber coolant valve is 100 % open before engine start. During engine operation, it will be 100 % open for throttle settings of 100 to 109 % for maximum cooling. For throttle settings between 65 to 100 %, its position will range from 66.4 to 100 % open for reduced cooling. A coolant, or heat transfer fluid, is a fluid which flows through a device in order to prevent its overheating, transferring the heat produced by the device to other devices that utilize or dissipate it. ...
Combustion chamber and nozzle
 Space Shuttle Main Engine test firing Each engine main combustion chamber receives fuel-rich hot gas from a hot-gas manifold cooling circuit. The gaseous hydrogen and liquid oxygen enter the chamber at the injector, which mixes the propellants. A small augmented spark igniter chamber is located in the center of the injector. The dual-redundant igniter is used during the engine start sequence to initiate combustion. The igniters are turned off after approximately three seconds because the combustion process is self-sustaining. The main injector and dome assembly is welded to the hot-gas manifold. The main combustion chamber also is bolted to the hot-gas manifold. Image File history File links Size of this preview: 480 × 600 pixelsFull resolution (2400 × 3000 pixel, file size: 5. ...
Image File history File links Size of this preview: 480 × 600 pixelsFull resolution (2400 × 3000 pixel, file size: 5. ...
The inner surface of each combustion chamber, as well as the inner surface of each nozzle, is cooled by liquid hydrogen flowing through braised stainless steel tube-wall coolant passages. The nozzle assembly is a bell-shaped extension bolted to the main combustion chamber. The nozzle is 2.9 m (113 inches) long, and the outside diameter of the exit is 2.4 m (94 inches). A support ring welded to the forward end of the nozzle is the engine attach point to the orbiter-supplied heat shield. Thermal protection is necessary because of the exposure portions of the nozzles experience during the launch, ascent, on-orbit and entry phases of a mission. The insulation consists of four layers of metallic batting covered with a metallic foil and screening.
Main valves The five propellant valves on each engine (oxidizer preburner oxidizer, fuel preburner oxidizer, main oxidizer, main fuel, and chamber coolant) are hydraulically actuated and controlled by electrical signals from the engine controller. They can be fully closed by using the MPS engine helium supply system as a backup actuation system.
The main oxidizer valve and fuel bleed valve are used after shutdown. The main oxidizer valve is opened during a propellant dump to allow residual liquid oxygen to be dumped overboard through the engine, and the fuel bleed valve is opened to allow residual liquid hydrogen to be dumped through the liquid hydrogen fill and drain valves overboard. After the dump is completed, the valves close and remain closed for the remainder of the mission.
Gimbal The gimbal bearing is bolted to the main injector and dome assembly and is the thrust interface between the engine and orbiter. The bearing assembly is approximately 290 by 360 mm (11.3 by 14 inches). A gimbal is a mechanical device that allows the rotation of an object in multiple dimensions. ...
A bearing is a device to permit constrained relative motion between two parts, typically rotation or linear movement. ...
The low-pressure oxygen and low-pressure fuel turbopumps are mounted 180 degrees apart on the orbiter's aft fuselage thrust structure. The lines from the low-pressure turbopumps to the high-pressure turbopumps contain flexible bellows that enable the low-pressure turbopumps to remain stationary while the rest of the engine is gimbaled for thrust vector control. The liquid hydrogen line from the LPFTP to the HPFTP is insulated to prevent the formation of liquid air.
SSME thrust specifications SSME thrust can be throttled between 67 to 109% of rated thrust. Current launches use 104.5%, with 106 or 109% available for abort contingencies. Thrust can be specified as sea level or vacuum thrust. Vacuum thrust will be higher due to no atmospheric effects. A Space Shuttle abort is an emergency procedure due to equipment failure on NASAs Space Shuttle, most commonly during ascent. ...
- 100% thrust (sea level / vacuum): 1670 kN / 2090 kN (375,000 lbf / 470,000 lbf)
- 104.5% thrust (sea level / vacuum): 1750 kN / 2170 kN (393,800 lbf / 488,800 lbf)
- 109% thrust (sea level / vacuum): 1860 kN / 2280 kN (417,300 lbf / 513,250 lbf)
The SSME after the Shuttle era
 Main engine of a US Space Shuttle Originally, the SSME was to see service in the post-Shuttle era as the main engines for the unmanned Ares V cargo-launch vehicle and as a second-stage engine for the manned-rated Ares I crew-launch vehicle. Although the use of the SSME seemed good on paper, as it would use current Shuttle technology after the Shuttle's retirement in 2010, it had several drawbacks: Image File history File linksMetadata Download high resolution version (1536x2048, 2466 KB) Summary Photo of a Space shuttle engine on display at a visitor complex on NASA land in Cape Canaveral, Florida. ...
Image File history File linksMetadata Download high resolution version (1536x2048, 2466 KB) Summary Photo of a Space shuttle engine on display at a visitor complex on NASA land in Cape Canaveral, Florida. ...
The Ares V (formerly known at the Cargo Launch Vehicle or CaLV) is the cargo launch component of Project Constellation. ...
It has been suggested that Ares I-1 be merged into this article or section. ...
- It would not be reusable, as they would be permanently attached to the discarded stage(s).
- It would have to undergo a flight-readiness firing (FRF) before installation – the so-called "Main Engine Test" that NASA conducted with each new Orbiter and prior to the STS-26 flight.
- It would be expensive and time-consuming to convert the ground-started SSME to an air-started version for the Ares I second stage.
With several design changes to the Ares I and Ares V rockets, the SSME will be replaced with a single J-2X engine for the Ares I second stage. The Ares V will use five modified RS-68 engines (which is based on both the SSME and Apollo-era J-2 engine) for its core stage. Hence the SSMEs will be retired along with the Shuttle fleet. STS-26 was a space shuttle mission by NASA using the Space Shuttle Discovery. ...
J-2 Rocket Engine Specifications. ...
The RS-68 (Rocket System 68) is the largest existing liquid hydrogen / liquid oxygen engine, producing a thrust of 650,000 lbf (2. ...
Specifications - Design Altitude = 60,000 feet
- Nozzle Mach Number = 5.05 (calculated)
- Throat Area = 93 square inches
- Nozzle Area = 50.265 square feet
- Chamber Pressure = 2747 psi at 100% power
- Exit Pressure = 1.049 psi (calculated)
- Burn Time = 520 seconds
- Vacuum Isp = 452.5 seconds
- Vacuum Thrust per Engine = 490,850 pounds at 104.5% of Design Thrust
See also Main Propulsion Test Article being lifted onto its test stand in 1977. ...
This article does not cite any references or sources. ...
References PDF is an abbreviation with several meanings: Portable Document Format Post-doctoral fellowship Probability density function There also is an electronic design automation company named PDF Solutions. ...
The Boeing Company (NYSE: BA, TYO: 7661 ) is a major aerospace and defense corporation, originally founded by William Boeing. ...
The National Aeronautics and Space Administration (NASA) is an agency of the United States government, responsible for the nations public space program. ...
The National Aeronautics and Space Administration (NASA) is an agency of the United States government, responsible for the nations public space program. ...
PDF is an abbreviation with several meanings: Portable Document Format Post-doctoral fellowship Probability density function There also is an electronic design automation company named PDF Solutions. ...
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