Aerojet AJ-550 Space Shuttle main engine
AJ-550 liquid hydrogen/oxygen staged combustion cycle space shuttle engine, describing preburner and main injector, turbopump and combustion chamber construction
Wilson, L. D.↗
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A History of Welding on the Space Shuttle Main Engine (1975 to 2010)
The Space Shuttle Main Engine (SSME) is a high performance, throttleable, liquid hydrogen fueled rocket engine. High thrust and specific impulse (Isp) are achieved through a staged combustion engine cycle, combined with high combustion pressure (approx.3000psi) generated by the two-stage pump and combustion process. The SSME is continuously throttleable from 67% to 109% of design thrust level. The design criteria for this engine maximize performance and weight, resulting in a 7,800 pound rocket engine that produces over a half million pounds of thrust in vacuum with a specific impulse of 452/sec. It is the most reliable rocket engine in the world, accumulating over one million seconds of hot-fire time and achieving 100% flight success in the Space Shuttle program. A rocket engine with the unique combination of high reliability, performance, and reusability comes at the expense of manufacturing simplicity. Several innovative design features and fabrication techniques are unique to this engine. This is as true for welding as any other manufacturing process. For many of the weld joints it seemed mean cheating physics and metallurgy to meet the requirements. This paper will present a history of the welding used to produce the world s highest performance throttleable rocket engine.
Zimmerman, Frank R.↗
Space Shuttle Main Engine development /May 1980/
The Space Shuttle Main Engine is the most advanced liquid propellant rocket engine ever developed. During the last year, significant progess has been made toward the identification and solution of several design weaknesses. The initial two test series to certify the engine's readiness for manned flight have been completed, and additional test series are in progress. Operation of the total propulsion system has been demonstrated by a successful series of flight-simulation tests using the three-engine cluster Main Propulsion Test Article. The first set of flight engines has been acceptance tested for use in Shuttle Orbiter 102 (Columbia) for the first manned orbital flight in late 1980 or early 1981. Engine development is continuing with initial demonstrations of full-power level (109%) operation capability.
Sanchini, D. J.↗
Space Shuttle Main Engine - The Relentless Pursuit of Improvement
The Space Shuttle Main Engine (SSME) is the only reusable large liquid rocket engine ever developed. The specific impulse delivered by the staged combustion cycle, substantially higher than previous rocket engines, minimized volume and weight for the integrated vehicle. The dual pre-burner configuration permitted precise mixture ratio and thrust control while the fully redundant controller and avionics provided a very high degree of system reliability and health diagnosis. The main engine controller design was the first rocket engine application to incorporate digital processing. The engine was required to operate at a high chamber pressure to minimize engine volume and weight. Power level throttling was required to minimize structural loads on the vehicle early in flight and acceleration levels on the crew late in ascent. Fatigue capability, strength, ease of assembly and disassembly, inspectability, and materials compatibility were all major considerations in achieving a fully reusable design. During the multi-decade program the design evolved substantially using a series of block upgrades. A number of materials and manufacturing challenges were encountered throughout SSME s history. Significant development was required for the final configuration of the high pressure turbopumps. Fracture control was implemented to assess life limits of critical materials and components. Survival in the hydrogen environment required assessment of hydrogen embrittlement. Instrumentation systems were a challenge due to the harsh thermal and dynamic environments within the engine. Extensive inspection procedures were developed to assess the engine components between flights. The Space Shuttle Main Engine achieved a remarkable flight performance record. All flights were successful with only one mission requiring an ascent abort condition, which still resulted in an acceptable orbit and mission. This was achieved in large part via extensive ground testing to fully characterize performance and to establish acceptable life limits. During the program over a million seconds of accumulated test and flight time was achieved. Post flight inspection and assessment was a key part of assuring proper performance of the flight hardware. By the end of the program the predicted reliability had improved by a factor of four. These unique challenges, evolution of the design, and the resulting reliability will be discussed in this paper.
VanHooser, Katherine P.↗
Leak Location and Classification in the Space Shuttle Main Engine Nozzle by Infrared Testing
The Space Shuttle Main Engine (SSME) is composed of cooling tubes brazed to the inside of a conical structural jacket. Because of the geometry there are regions that can't be inspected for leaks using the bubble solution and low-pressure method. The temperature change due escaping gas is detectable on the surface of the nozzle under the correct conditions. The methods and results presented in this summary address the thermographic identification of leaks in the Space Shuttle Main Engine nozzles. A highly sensitive digital infrared camera is used to record the minute temperature change associated with a leak source, such as a crack or pinhole, hidden within the nozzle wall by observing the inner "hot wall" surface as the nozzle is pressurized. These images are enhanced by digitally subtracting a thermal reference image taken before pressurization, greatly diminishing background noise. The method provides a nonintrusive way of localizing the tube that is leaking and the exact leak source position to within a very small axial distance. Many of the factors that influence the inspectability of the nozzle are addressed; including pressure rate, peak pressure, gas type, ambient temperature and surface preparation.
Russell, Samuel S.↗
Shuttle Centaur engine cooldown evaluation and effects of expanded inlets on start transient
As part of the integration of the RL10 engine into the Shuttle Centaur vehicle, a satisfactory method of conditioning the engine to operating temperatures had to be established. This procedure, known as cooldown, is different from the existing Atlas Centaur due to vehicle configuration and mission profile differenced. The program is described, and the results of a Shuttle Centaur cooldown program are reported. Mission peculiarities cause substantial variation in propellant inlet conditions between the substantiated Atlas Centaur and Shuttle Centaur with the Shuttle Centaur having much larger variation in conditions. A test program was conducted to demonstrate operation of the RL10 engine over the expanded inlet conditions. As a result of this program, the Shuttle Centaur requirements were proven satisfactory. Minor configuration changes incorporated as a result of this program provide substantial reduction in cooldown propellant consumption.
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Experimental measurements of the Space Shuttle main engine fuel and oxygen turbopump vibration characteristics
The vibration characteristics of the SSME (Space Shuttle main engine) are dealt with. The Space Shuttle engine consists of a main rocket nozzle and attached to it are high pressure fuel and oxygen pumps. Various vibration problems have been encountered with both the hydrogen and oxygen pumps. The vibration spectrum of the hydrogen and oxygen pumps has been analyzed by various techniques using synchronous tracking filters and FFT analyzers. The experimental data has been correlated to theoretical predictions of resonance frequencies.
Gunter, E. J.↗
Space shuttle main engine definition (phase B). Volume 2: Avionics
The advent of the space shuttle engine with its requirements for high specific impulse, long life, and low cost have dictated a combustion cycle and a closed loop control system to allow the engine components to run close to operating limits. These performance requirements, combined with the necessity for low operational costs, have placed new demands on rocket engine control, system checkout, and diagnosis technology. Based on considerations of precision environment, and compatibility with vehicle interface commands, an electronic control, makes available many functions that logically provide the information required for engine system checkout and diagnosis.
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Space shuttle RCS engine
The design of the space shuttle RCS engine has the primary objective of reusability with minimum servicing. Engine S/N FT-2A has successfully completed all ten environmental (salt water spray, sand and dust, vibration and humidity) and hot fire cycles with no change in engine performance (steady state or pulse mode).
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Space Shuttle Main Engine
Significant features of the Space Shuttle Main Engine (SSME) include a staged combustion power cycle, high area ratio nozzle expansion, throttling capability, and a computer operated control system. These main design features are discussed along with development test results.
Thompson, J. R., Jr.↗
Space Shuttle Main Engine
Significant features of the Space Shuttle Main Engine (SSME) include a staged combustion power cycle developing chamber pressure in excess of 3000 psia, high area ratio nozzle expansion, throttling capability, and a computer-operated engine control system. This paper examines the current status of the SSME with attention given to engine performance, system characteristics, and test results. A comparison of the SSME development and certification programs with engines successfully used in the Saturn Program is presented.
Thompson, J. R., Jr.↗
An investigation of space shuttle main engine shutdown chugging instability
The Space Shuttle Main Engines experience a low frequency pressure pulsation in both the fuel and oxidizer preburners during shutdown. The pressure pulsations (chugging) occur during the helium purge of oxidizer from the preburner manifolds. Possible causes and triggering mechanisms are considered as details of the chugging process are presented and discussed. A simple chugging model capable of predicting pressure excursion amplitudes and frequencies is proposed and preliminary results presented.
George, P. E., II↗
Investigation and modeling of space shuttle main engine shutdown transient chugging
The space shuttle main engines experience a low frequency pressure pulsation in both the fuel and oxidizer preburners during the shutdown transient. This pressure pulsation, called chugging, has been linked to undesirable bearing loads and possible damage to the spark ignitor supply piping for the fuel preburner. The problem is briefly described and a model is proposed that includes: (1) a transient stirred tank reactor model for the combustion chamber, (2) a resistance capacitance model for the supply piping and (3) purge gas/liquid oxygen interface tracking.
George, P. E., II↗
Development history of the Space Shuttle Main Engine
The development of the Space Shuttle Main Engine has provided a high performance, reusable component for the Space Transportation System. A discussion of how ground testing identified problems and their resolution paved the way for certification of the engine for flight. A launch summary and a discussion of launch anomalies are included. Continuing improvements and established overhaul criteria are described which will extend the operating life and allow each engine to be used efficiently.
Peterson, T. J.↗
Space shuttle main engine vibration data base
The Space Shuttle Main Engine Vibration Data Base is described. Included is a detailed description of the data base components, the data acquisition process, the more sophisticated software routines, and the future data acquisition methods. Several figures and plots are provided to illustrate the various output formats accessible to the user. The numerous vibration data recall and analysis capabilities available through automated data base techniques are revealed.
Lewallen, Pat↗
Spares Management : Optimizing Hardware Usage for the Space Shuttle Main Engine
The complexity of the Space Shuttle Main Engine (SSME), combined with mounting requirements to reduce operations costs have increased demands for accurate tracking, maintenance, and projections of SSME assets. The SSME Logistics Team is developing an integrated asset management process. This PC-based tool provides a user-friendly asset database for daily decision making, plus a variable-input hardware usage simulation with complex logic yielding output that addresses essential asset management issues. Cycle times on critical tasks are significantly reduced. Associated costs have decreased as asset data quality and decision-making capability has increased.
Gulbrandsen, K. A.↗
Engine systems analysis results of the Space Shuttle Main Engine redesigned powerhead initial engine level testing
Engineers regularly analyze SSME ground test and flight data with respect to engine systems performance. Recently, a redesigned SSME powerhead was introduced to engine-level testing in part to increase engine operational margins through optimization of the engine internal environment. This paper presents an overview of the MSFC personnel engine systems analysis results and conclusions reached from initial engine level testing of the redesigned powerhead, and further redesigns incorporated to eliminate accelerated main injector baffle and main combustion chamber hot gas wall degradation. The conclusions are drawn from instrumented engine ground test data and hardware integrity analysis reports and address initial engine test results with respect to the apparent design change effects on engine system and component operation.
Sander, Erik J.↗
Presenting the Shuttle Main Engine Software
Originally, this project was to produce an animated Powerpoint presentation of the 'Shuttle Engine and its Software' and to produce a web page with animation including the same materials but with greater detail in the description of the software. The principal emphasis was to be on the web page. Midway through the first year of the project, we were advised by the technical coordinator of this work at MSFC to concentrate on the web page alone. Also, the project was expanded to include a web presentation of the MRECS (Modular Rocket Control System). For the SSME project, the web page presentation has been completed. The integration of the animation into the web page is complete although we have been asked to speed up the animation. Also, the addition of greater detail to the description of the SSME controller software has been added. Much of the work on this program was done by students as their task for their senior project course, the capstone course of their program of study. The students gained a great deal from this project. They have learned to use VISIO, POWERPOINT, PHOTOSHOP, and several web page software packages. The starting point for this project was a PowerPoint presentation by the PI while on a Summer Faculty Fellowship at MSFC. For this project, about half of the drawings of the SSME were improved and about half were completely redrawn. The original still drawings have been animated to illustrate the fuel flow through the SSME system.
Schreur, Barbara↗