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“Different views of Space Shuttle Main Engine test firings on all three test stands including closeup of engine, day, and night firings are presented.”
Public domain film from NASA, slightly cropped to remove uneven edges, with the aspect ratio corrected, and mild video noise reduction applied.
The soundtrack was also processed with volume normalization, noise reduction, clipping reduction, and/or equalization (the resulting sound, though not perfect, is far less noisy than the original).
The 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 of America 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 453 seconds in a vacuum, or 363 seconds at sea level (effective exhaust velocities of 4,440 m/s and 3,560 m/s respectively), consumes 1,340 L (350 US gal) of propellant per second, has a mass of approximately 3.5 tonnes (7,700 pounds) and is capable of throttling between 67% and 111% of its rated power level in one-percent increments. The RS-25 operates at extreme temperatures, with the liquid hydrogen fuel being stored at −250 °C (−418 °F) while the temperature in the combustion chamber reaches 3,315 °C (6,000 °F), higher than the boiling point of iron.
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.
On the Space Launch System (SLS), expendable versions of the engines are planned to be used in clusters of three, four or five, and draw their propellant from the rocket’s core stage. They provide propulsion during the first stage flight of the SLS, with additional thrust coming from two boosters. Following staging, the engines are discarded along with the rest of the core stage…
The RS-25 engine consists of various pumps, valves and other components which work in concert to produce thrust. Fuel (liquid hydrogen) and oxidizer (liquid oxygen) from the Space Shuttle external tank entered the orbiter at the umbilical disconnect valves, and from there flowed through the orbiter’s main propulsion system (MPS) feed lines; whereas in the Space Launch System (SLS), fuel and oxidiser from the rocket’s core stage will flow directly into the MPS lines. Once in the MPS lines, the fuel and oxidizer each branch out into separate paths to each engine (three on the Space Shuttle, up to five on the SLS). In each branch, prevalves then allow the propellants to enter the engine.
Once in the engine, the propellants flow through low-pressure fuel and oxidizer turbopumps (LPFTP and LPOTP), and from there into high-pressure turbopumps (HPFTP and HPOTP). From these HPTPs the propellants take different routes through the engine…
Once in the injectors, the propellants are mixed and injected into the main combustion chamber where they are ignited. The burning propellant mixture is then ejected through the throat and bell of the engine’s nozzle, the pressure of which creates the thrust…
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