Lessons in Systems Engineering - The SSME Weight Growth History
This viewgraph presentation describes the Space Shuttle Main Engine (SSME) weight growth history and lessons learned from SSME weight imbalances.
Ryan, Richard↗
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Purge Monitoring Technology for Gaseous Helium (GHe) Conservation
John C. Stennis Space Center provides rocket engine propulsion testing for the NASA space programs. Since the development of the Space Shuttle, every Space Shuttle Main Engine (SSME) has gone through acceptance testing before going to Kennedy Space Center for integration into the Space Shuttle. The SSME is a large cryogenic rocket engine that used Liquid Oxygen (LO2) and Liquid Hydrogen (LH2) as propellants. Due to the extremely cold cryogenic conditions of this environment, an inert gas, helium, is used as a purge for the engine and propellant lines since it can be used without freezing in the cryogenic environment. As NASA moves forward with the development of the new ARES V launch system, the main engines as well as the upper stage engine will use cryogenic propellants and will require gaseous helium during the development testing of each of these engines. The main engine for the ARES V will be similar in size to the SSME.
Dickey, Jonathan↗
NASA Applications and Lessons Learned in Reliability Engineering
Since the Shuttle Challenger accident in 1986, communities across NASA have been developing and extensively using quantitative reliability and risk assessment methods in their decision making process. This paper discusses several reliability engineering applications that NASA has used over the year to support the design, development, and operation of critical space flight hardware. Specifically, the paper discusses several reliability engineering applications used by NASA in areas such as risk management, inspection policies, components upgrades, reliability growth, integrated failure analysis, and physics based probabilistic engineering analysis. In each of these areas, the paper provides a brief discussion of a case study to demonstrate the value added and the criticality of reliability engineering in supporting NASA project and program decisions to fly safely. Examples of these case studies discussed are reliability based life limit extension of Shuttle Space Main Engine (SSME) hardware, Reliability based inspection policies for Auxiliary Power Unit (APU) turbine disc, probabilistic structural engineering analysis for reliability prediction of the SSME alternate turbo-pump development, impact of ET foam reliability on the Space Shuttle System risk, and reliability based Space Shuttle upgrade for safety. Special attention is given in this paper to the physics based probabilistic engineering analysis applications and their critical role in evaluating the reliability of NASA development hardware including their potential use in a research and technology development environment.
Safie, Fayssal M.↗
Hydrogen Reclamation and Reutilization
John C. Stennis Space Center (SSC) provides rocket engine propulsion testing for NASA's space programs. Since the development of the Space Shuttle, every Space Shuttle Main Engine (SSME) has undergone acceptance testing at SSC before going to Kennedy Space Center (KSC) for integration into the Space Shuttle. The SSME is a large cryogenic rocket engine that uses Liquid Hydrogen (LH2) as the fuel. As NASA moves to the new ARES V launch system, the main engines on the new vehicle, as well as the upper stage engine, are currently base lined to be cryogenic rocket engines that will also use LH2. The main rocket engines for the ARES V will be larger than the SSME, while the upper stage engine will be approximately half that size. As a result, significant quantities of hydrogen will be required during the development, testing, and operation of these rocket engines.
Hebert, Bartt↗
Smart and Intelligent Sensors
John C. Stennis Space Center (SSC) provides rocket engine propulsion testing for NASA's space programs. Since the development of the Space Shuttle, every Space Shuttle Main Engine (SSME) has undergone acceptance testing at SSC before going to Kennedy Space Center (KSC) for integration into the Space Shuttle. The SSME is a large cryogenic rocket engine that uses Liquid Hydrogen (LH2) as the fuel. As NASA moves to the new ARES V launch system, the main engines on the new vehicle, as well as the upper stage engine, are currently base lined to be cryogenic rocket engines that will also use LH2. The main rocket engines for the ARES V will be larger than the SSME, while the upper stage engine will be approximately half that size. As a result, significant quantities of hydrogen will be required during the development, testing, and operation of these rocket engines.Better approaches are needed to simplify sensor integration and help reduce life-cycle costs. 1.Smarter sensors. Sensor integration should be a matter of "plug-and-play" making sensors easier to add to a system. Sensors that implement new standards can help address this problem; for example, IEEE STD 1451.4 defines transducer electronic data sheet (TEDS) templates for commonly used sensors such as bridge elements and thermocouples. When a 1451.4 compliant smart sensor is connected to a system that can read the TEDS memory, all information needed to configure the data acquisition system can be uploaded. This reduces the amount of labor required and helps minimize configuration errors. 2.Intelligent sensors. Data received from a sensor be scaled, linearized; and converted to engineering units. Methods to reduce sensor processing overhead at the application node are needed. Smart sensors using low-cost microprocessors with integral data acquisition and communication support offer the means to add these capabilities. Once a processor is embedded, other features can be added; for example, intelligent sensors can make a health assessment to inform the data acquisition client when sensor performance is suspect. 3.Distributed sample synchronization. Networks of sensors require new ways for synchronizing samples. Standards that address the distributed timing problem (for example, IEEE STD 1588) provide the means to aggregate samples from many distributed smart sensors with sub-microsecond accuracy. 4. Reduction in interconnect. Alternative means are needed to reduce the frequent problems associated with cabling and connectors. Wireless technologies offer the promise of reducing interconnects and simultaneously making it easy to quickly add a sensor to a system.
Lansaw, John↗
Supercharged two-cycle engines employing novel single element reciprocating shuttle inlet valve mechanisms and with a variable compression ratio
This invention relates to novel reciprocating shuttle inlet valves, effective with every type of two-cycle engine, from small high-speed single cylinder model engines, to large low-speed multiple cylinder engines, employing spark or compression ignition. Also permitting the elimination of out-of-phase piston arrangements to control scavenging and supercharging of opposed-piston engines. The reciprocating shuttle inlet valve (32) and its operating mechanism (34) is constructed as a single and simple uncomplicated member, in combination with the lost-motion abutments, (46) and (48), formed in a piston skirt, obviating the need for any complex mechanisms or auxiliary drives, unaffected by heat, friction, wear or inertial forces. The reciprocating shuttle inlet valve retains the simplicity and advantages of two-cycle engines, while permitting an increase in volumetric efficiency and performance, thereby increasing the range of usefulness of two-cycle engines into many areas that are now dominated by the four-cycle engine.
Wiesen, Bernard↗
Balancing low cost with reliable operation in the rotordynamic design of the ALS Liquid Hydrogen Fuel Turbopump
The Air Force/NASA Advanced Launch System (ALS) Liquid Hydrogen Fuel Turbopump (FTP) has primary design goals of low cost and high reliability, with performance and weight having less importance. This approach is atypical compared with other rocket engine turbopump design efforts, such as on the Space Shuttle Main Engine (SSME), which emphasized high performance and low weight. Similar to the SSME turbopumps, the ALS FTP operates supercritically, which implies that stability and bearing loads strongly influence the design. In addition, the use of low cost/high reliability features in the ALS FTP such as hydrostatic bearings, relaxed seal clearances, and unshrouded turbine blades also have a negative influence on rotordynamics. This paper discusses the analysis conducted to achieve a balance between low cost and acceptable rotordynamic behavior, to ensure that the ALS FTP will operate reliably without subsynchronous instabilities or excessive bearing loads.
Greenhill, L. M.↗
Reusable rocket engine intelligent control system framework design, phase 2
Elements of an advanced functional framework for reusable rocket engine propulsion system control are presented for the Space Shuttle Main Engine (SSME) demonstration case. Functional elements of the baseline functional framework are defined in detail. The SSME failure modes are evaluated and specific failure modes identified for inclusion in the advanced functional framework diagnostic system. Active control of the SSME start transient is investigated, leading to the identification of a promising approach to mitigating start transient excursions. Key elements of the functional framework are simulated and demonstration cases are provided. Finally, the advanced function framework for control of reusable rocket engines is presented.
Nemeth, ED↗
Vehicle health management using adaptive techniques
Automated engine diagnostics using cognitive computing methodologies are investigated. Space shuttle main engine vibrational data is used to test the algorithms.
Kim, J. H.↗
Innovative Techniques Simplify Vibration Analysis
In the early years of development, Marshall Space Flight Center engineers encountered challenges related to components in the space shuttle main engine. To assess the problems, they evaluated the effects of vibration and oscillation. To enhance the method of vibration signal analysis, Marshall awarded Small Business Innovation Research (SBIR) contracts to AI Signal Research, Inc. (ASRI), in Huntsville, Alabama. ASRI developed a software package called PC-SIGNAL that NASA now employs on a daily basis, and in 2009, the PKP-Module won Marshall s Software of the Year award. The technology is also used in many industries: aircraft and helicopter, rocket engine manufacturing, transportation, and nuclear power."
Source record↗
Technology considerations for main engine specific impulse
Combustion, cooling, nozzle design, and specific impulse prediction for space shuttle main engine
Kors, D. L.↗
Artificial intelligence techniques for ground test monitoring of rocket engines
An expert system is being developed which can detect anomalies in Space Shuttle Main Engine (SSME) sensor data significantly earlier than the redline algorithm currently in use. The training of such an expert system focuses on two approaches which are based on low frequency and high frequency analyses of sensor data. Both approaches are being tested on data from SSME tests and their results compared with the findings of NASA and Rocketdyne experts. Prototype implementations have detected the presence of anomalies earlier than the redline algorithms that are in use currently. It therefore appears that these approaches have the potential of detecting anomalies early eneough to shut down the engine or take other corrective action before severe damage to the engine occurs.
Ali, Moonis↗
Navier-Stokes computations with finite-rate chemistry for LO2/LH2 rocket engine plume flow studies
Computational fluid dynamics methods have been developed and applied to Space Shuttle Main Engine LO2/LH2 plume flow simulation/analysis of airloading and convective base heating effects on the vehicle at high flight velocities and altitudes. New methods are described which were applied to the simulation of a Return-to-Launch-Site abort where the vehicle would fly briefly at negative angles of attack into its own plume. A simplified two-perfect-gases-mixing approach is used where one gas is the plume and the other is air at 180-deg and 135-deg flight angle of attack. Related research has resulted in real gas multiple-plume interaction methods with finite-rate chemistry described herein which are applied to the same high-altitude-flight conditions of 0 deg angle of attack. Continuing research plans are to study Orbiter wake/plume flows at several Mach numbers and altitudes during ascent and then to merge this model with the Shuttle 'nose-to-tail' aerodynamic and SRB plume models for an overall 'nose-to-plume' capability. These new methods are also applicable to future launch vehicles using clustered-engine LO2/LH2 propulsion.
Dougherty, N. Sam↗
External tank aerothermal design criteria verification
If a Space Shuttle Main Engine (SSME) fails during the initial 160 seconds of the Shuttle flight, a return-to-launch-site maneuver will be implemented. The period of concern for this task is the pitch-around maneuver when the vehicle is flying backward. The intent of this report is to identify and define the flowfield at the most critical locations from an environment perspective. The solution procedure used to predict the plume heating rates involves both computational analysis and engineering modeling.
Praharaj, Sarat C.↗
Advanced High Pressure O2/H2 Technology
Activities in the development of advanced high pressure oxygen-hydrogen stage combustion rocket engines are reported. Particular emphasis is given to the Space Shuttle main engine. The areas of engine technology discussed include fracture and fatigue in engine components, manufacturing and producibility engineering, materials, bearing technology, structure dynamics, fluid dynamics, and instrumentation technology.
Morea, S. F.↗
Composite Loads Spectra for Select Space Propulsion Structural Components: Probabilistic Load Model Development
This effort is in support of the development of the expert system of computer codes to predict the loads on select structural components of a space propulsion engine. The development will be based primarily on the space shuttle main engine (SSME) test data base. Because of random variations of the many different sources of the loadings on the selected structural components and transients, a probabilistic approach to the problems was adopted. The goal of this task is to characterize all of the individual sources of loads at critical structural locations, such as the turbine blades, the transfer ducts, and liquid oxygen posts, using state-of-the-art probabilistic methods with varying levels of sophistication. The second phase of this work is the development of a composite load model based on a probabilistic synthesis of the individual load model previously developed. This model will be based on the stochastic combination of the load variables and not on the physical process for the combination of the individual loads to the composite load seen by the selected structural components.
Kurth, R.↗
Space Shuttle redesign status
NASA has conducted an extensive redesign effort for the Space Shutle in the aftermath of the STS 51-L Challenger accident, encompassing not only Shuttle vehicle and booster design but also such system-wide factors as organizational structure, management procedures, flight safety, flight operations, sustainable flight rate, and maintenance safeguards. Attention is presently given to Solid Rocket Booster redesign features, the Shuttle Main Engine's redesigned high pressure fuel and oxidizer turbopumps, the Shuttle Orbiter's braking and rollout (landing gear) system, the entry control mode of the flight control system, a 'split-S' abort maneuver for the Orbiter, and crew escape capsule proposals.
Brand, Vance D.↗
Thin-film sensors for reusable space propulsion systems
Thin-film thermocouples (TFTCs) were developed for aircraft gas turbine engines and are in use for temperature measurement on turbine blades up to 1800 F. Established aircraft engine gas turbine technology is currently being adapted to turbine engine blade materials and the environment encountered in the Space Shuttle Main Engine (SSME)-severe thermal shock from cryogenic fuel to combustion temperatures. Initial results with coupons of MAR M-246 (+Hf) and PWA 1480 were followed by fabrication of TFTC on SSME turbine blades. Current efforts are focused on preparation for testing in the Turbine Blade Tester at NASA Marshall Space Flight Center.
Hepp, Aloysius F.↗