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Results for “Requirements engineering”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS2009

Engine Gimbal Requirements for Ground Testing of J-2X

Based on the Apollo-era J-2 that powered the second and third stages of the Saturn V, the current J-2X is the liquid hydrogen and oxygen high-altitude rocket engine in development for both the Ares I Upper Stage and Ares V Earth Departure Stage. During my summer 2009 internship, J-2X was at a stage in its design maturity where verification testing needed to be considered for the benefit of adequate test facility preparation. My task was to focus on gimbal requirements and gimbal related hot-fire test plans. Facility capabilities were also of interest, specifically for hot-fire testing slated to occur at test stands A-1, A-2, and A-3 at Stennis Space Center(SSC) in Bay St. Louis, Mississippi. Gimbal requirements and stage interface conditions were investigated by applying a top-to-bottom systems engineering approach, which involved system level requirements, engine level requirements from both government and engine contractor perspectives, component level requirements, and the J-2X to Upper Stage and Earth Departure Stage interface control documents. Previous hydrogen and oxygen liquid rocket engine gimbal verification methods were researched for a glimpse at lessons learned. Discussion among the J-2X community affected by gimballing was organized to obtain input relative to proper verification of their respective component. Implementing suggestions such as gimbal pattern, angulated dwell time, altitude testing options, power level, and feed line orientation, I was able to match tests to test stands in the A Complex at SSC. Potential test capability gaps and risks were identified and pursued. The culmination of all these efforts was to coordinate with SSC to define additional facility requirements for both the A-3 altitude test stand that is currently under construction and the A-1 sea level test stand which is being renovated

Kovalcik, Julia↗
NASA NTRS2021

A Fully Automated Approach to Requirement Extraction from Design Documents

Design documents are intended to outline the goalsof a system or project, which are utilized in the creation ofspecific software requirements. At the NASA Jet PropulsionLaboratory, California Institute of Technology, Functional DesignDescription (FDD) documents describe the scope of theproject and reflect the design and implementation of the system.The specifications in the document are not explicitly writtenas requirements, though these guidelines must be reflected inthe official software requirements. In this work we present afully automatic approach to extracting software requirementsfrom design documents as well as comparing the extractedrequirements to those that exist in the official software requirementdatabase. We do this through (1) sentence extractionfrom the design document, (2) the incorporation of coreferenttext, and (3) aligning the extracted text to the official softwarerequirements. Via natural language processing and informationretrieval techniques, our system results in an automated processthat ensures that the specifications in the design document resultin official software requirements. We find that extraction ofimperatives results in a recall rate of 0.73 and the TF-IDF cosinesimilarity metric is shown to be a useful and successful way tocompare requirements.Though there has been recent work investigating the usefulnessof natural language processing techniques in requirement engineering,this has not been made use of in the aerospace industry.Aerospace requirement engineering is a field particularly ripefor this type of innovation because these techniques can bothautomate some of needlessly manual work and contribute toaerospace safety practices by identifying issues that a humanmay miss. We present the first fully automated approach thatextracts requirements from a design document and comparesthem to a database, and use these findings as encouragementfor future work that makes use of natural language processingtechniques in aerospace requirement engineering.

Briggs, Paul↗
NASA NTRS1968

Environmental requirements

Engineering models of Venus atmosphere, and application of thermal modeling to spacecraft sterilization

Source record↗
NASA NTRS1992

Orbit transfer rocket engine technology program: Advanced engine study

In Task D.6 of the Advanced Engine Study, three primary subtasks were accomplished: (1) design of parametric data; (2) engine requirement variation studies; and (3) vehicle study/engine study coordination. Parametric data were generated for vacuum thrusts ranging from 7500 lbf to 50,000 lbf, nozzle expansion ratios from 600 to 1200, and engine mixture ratios from 5:1 to 7:1. Failure Modes and Effects Analysis (FMEA) was used as a departure point for these parametric analyses. These data are intended to assist in definition and trade studies. In the Engine Requirements Variation Studies, the individual effects of increasing the throttling ratio from 10:1 to 20:1 and requiring the engine to operate at a maximum mixture ratio of 12:1 were determined. Off design engine balances were generated at these extreme conditions and individual component operating requirements analyzed in detail. Potential problems were identified and possible solutions generated. In the Vehicle Study/Engine Study coordination subtask, vehicle contractor support was provided as needed, addressing a variety of issues uncovered during vehicle trade studies. This support was primarily provided during Technical Interchange Meetings (TIM) in which Space Exploration Initiative (SEI) studies were addressed.

Erickson, C. M.↗
NASA NTRS2012

Development of a Compact, Deep-Penetrating Heat Flow Instrument for Lunar Landers: In-Situ Thermal Conductivity System

Geothermal heat flow is obtained as a product of the geothermal gradient and the thermal conductivity of the vertical soil/rock/regolith interval penetrated by the instrument. Heat flow measurements are a high priority for the geophysical network missions to the Moon recommended by the latest Decadal Survey and previously the International Lunar Network. One of the difficulties associated with lunar heat flow measurement on a robotic mission is that it requires excavation of a relatively deep (approx 3 m) hole in order to avoid the long-term temporal changes in lunar surface thermal environment affecting the subsurface temperature measurements. Such changes may be due to the 18.6-year-cylcle lunar precession, or may be initiated by presence of the lander itself. Therefore, a key science requirement for heat flow instruments for future lunar missions is to penetrate 3 m into the regolith and to measure both thermal gradient and thermal conductivity. Engineering requirements are that the instrument itself has minimal impact on the subsurface thermal regime and that it must be a low-mass and low-power system like any other science instrumentation on planetary landers. It would be very difficult to meet the engineering requirements, if the instrument utilizes a long (> 3 m) probe driven into the ground by a rotary or percussive drill. Here we report progress in our efforts to develop a new, compact lunar heat flow instrumentation that meets all of these science and engineering requirements.

Nagihara, S.↗
NASA NTRS2019

Multipoint Design and Optimization of a Turboshaft Engine for a Tiltwing Turboelectric Vertical Takeoff Landing Air Taxi

This paper describes the design of a turboshaft engine for a tiltwing air taxi application. In this case, the tiltwing air taxi is intended to fly a 400 nm mission with up to fifteen passengers. Engine requirements for the concept engine are taken from aircraft system studies where thrust is produced by four propellers driven by electric motors and powered by a single gas turbine engine. The purpose of this paper is to perform a cycle design optimization that minimizes fuel consumption and weight while respecting current technology limitations to meet mission requirements. To achieve results, the engine overall pressure ratio and maximum temperature at the exit of the combustor are set as the design parameters. Several sensitivity studies are also performed to visualize optimization trends. Results of the optimization study show solutions are heavily dependent on engine cooling flow requirements and exact mission requirements. This engine is intended for use in large system optimization research.

gas turbine↗
NASA NTRS2019

Multi-Point Design and Optimization of a Turboshaft Engine for a Tiltwing Turboelectric VTOL Air Taxi

This paper describes the design of a turboshaft engine for a tiltwing air taxi application. In this case, the tiltwing air taxi is intended to fly a 400-nautical mile mission with up to fifteen passengers. Engine requirements for the concept engine are taken from aircraft system studies where thrust is produced by four propellers driven by electric motors and powered by a single gas turbine engine. The purpose of this paper is to perform a cycle design optimization that minimizes fuel consumption and weight while respecting current technology limitations to meet mission requirements. To achieve results, the engine overall pressure ratio and maximum temperature at the exit of the combustor are set as the design parameters. Several sensitivity studies are also performed to visualize optimization trends. Results of the optimization study show solutions are heavily dependent on engine cooling flow requirements and exact mission requirements. This engine is intended for use in large system optimization research.

Optimization↗
NASA NTRSDate not supplied

Development and Implementation of a Small Satellite Systems Engineering Webinar Series: A Collaboration Between United Nations Office for Outer Space Affairs and National Aeronautics and Space Administration

The United Nations Office for Outer Space Affairs (UNOOSA) in collaboration with the National Aeronautics and Space Administration (NASA) established a webinar series on NASA systems engineering standards and practices for the purpose of sharing knowledge in this area through UNOOSA’s “Access to Space for All” which provides free and accessible educational content. Through NASA’s Small Spacecraft Systems Virtual Institute (S3VI), the four-part series was designed to cover basic systems engineering and project management skills that are fundamental for planning, developing, and implementing an experiment or a space project, and that serve as critical knowledge for those engaged in space activities, whether as a designer, builder, or manager of space infrastructure and services. This first series of webinars was convened over the course of November 2023 through February 2024. The webinar series was segmented into four one and a half hour webinars which covered topics related to the Fundamentals of Systems Engineering, Requirements and Systems Engineering, System Assembly, Integration and Test, and Spacecraft Handling, as well as an Introduction to the Small Spacecraft Systems Virtual Institute (S3VI). The agendas for the first three webinars focused on addressing a number of questions relevant to a particular topic. Examples of these questions include: What is systems engineering and what does a systems engineer do? Why does NASA use systems engineering? How do you define requirements for a small spacecraft mission? Why are requirements important to space missions? How are trade studies used to determine parts selection and why are they important? The final webinar of the first series provided interactive discussions and demonstrations of the S3VI tools; shared information on additional webinar opportunities offered by the S3VI; and reviewed databases curated by the S3VI that include the Small Satellite Reliability Initiative (SSRI) Knowledge Base Tool, Mission Design Tools, Small Spacecraft Information Search, and the State-of-the-Art (SoA) Small Spacecraft Report. Future webinar series will be conducted with topics are to be determined. The presenter will discuss details related to the first webinar series and future plans for additional series.

systems engineering↗
NASA NTRS1981

Flight test method for the determination of reciprocating engine cooling requirements

It is pointed out that the effective cooling of aircraft reciprocating engines is still a problem area for the general aviation industry. Miley et al. (1981) have reported the results of an investigation of problems associated with cooling and installation aerodynamics. A description is given of a flight test procedure which was developed in connection with the considered investigation. It is shown that the test procedure provides valid cooling requirements data for a particular installation. The data are in terms of easily measurable parameters. The employment of the test procedure, which is based on the NACA cooling correlation method, can lead to more effective cooling installations and the solution of existing cooling problems.

Miley, S. J.↗
NASA NTRS1991

Engineering knowledge requirements for sand and dust on Mars

The successful landing of human beings on Mars and the establishment of a permanent outpost there will require an understanding of the Martian environment by the engineers. A key feature of the Martian environment is the nearly ubiquitous presence of sand and dust. The process which the engineering community will undertake to determine the sensitivities of their designs to the current level of knowledge about Mars sand and dust is emphasized. The interaction of the engineering community with the space exploration initiative (SEI) mission planners and management is described.

Kaplan, D. I.↗
NASA NTRS2006

A Programmatic and Engineering Approach to the Development of a Nuclear Thermal Rocket for Space Exploration

With the announcement of the Vision for Space Exploration on January 14, 2004, there has been a renewed interest in nuclear thermal propulsion. Nuclear thermal propulsion is a leading candidate for in-space propulsion for human Mars missions; however, the cost to develop a nuclear thermal rocket engine system is uncertain. Key to determining the engine development cost will be the engine requirements, the technology used in the development and the development approach. The engine requirements and technology selection have not been defined and are awaiting definition of the Mars architecture and vehicle definitions. The paper discusses an engine development approach in light of top-level strategic questions and considerations for nuclear thermal propulsion and provides a suggested approach based on work conducted at the NASA Marshall Space Flight Center to support planning and requirements for the Prometheus Power and Propulsion Office. This work is intended to help support the development of a comprehensive strategy for nuclear thermal propulsion, to help reduce the uncertainty in the development cost estimate, and to help assess the potential value of and need for nuclear thermal propulsion for a human Mars mission.

Bordelon, Wayne J., Jr.↗
NASA NTRS1984

Practical flight test method for determining reciprocating engine cooling requirements

It is pointed out that efficient and effective cooling of air-cooled reciprocating aircraft engines is a continuing problem for the general aviation industry. Miley et al. (1981) have reported results of a study regarding the controlling variables for cooling and installation aerodynamics. The present investigation is concerned with experimental methods which were developed to determine cooling requirements of an instrumented prototype or production aircraft, taking into account a flight test procedure which has been refined and further verified with additional testing. It is shown that this test procedure represents a straightforward means of determining cooling requirements with minimal instrumentation. Attention is given to some background information, the development history of the NACA cooling correlation method, and the proposed modification of the NACA cooling correlation.

Ward, D. T.↗
NASA NTRS1993

An extended supersonic combustion model for the dynamic analysis of hypersonic vehicles

The development of an advanced dynamic model for aeroelastic hypersonic vehicles powered by air breathing engines requires an adequate engine model. This report provides a discussion of some of the more important features of supersonic combustion and their relevance to the analysis and design of supersonic ramjet engines. Of particular interest are those aspects of combustion that impact the control of the process. Furthermore, the report summarizes efforts to enhance the aeropropulsive/aeroelastic dynamic model developed at the Aerospace Research Center of Arizona State University by focusing on combustion and improved modeling of this flow. The expanded supersonic combustor model described here has the capability to model the effects of friction, area change, and mass addition, in addition to the heat addition process. A comparison is made of the results from four cases: (1) heat addition only; (2) heat addition plus friction; (3) heat addition, friction, and area reduction, and (4) heat addition, friction, area reduction, and mass addition. The relative impact of these effects on the Mach number, static temperature, and static pressure distributions within the combustor are then shown. Finally, the effects of frozen versus equilibrium flow conditions within the exhaust plume is discussed.

Bossard, J. A.↗
NASA NTRS2007

Nuclear Thermal Propulsion (NTP) Development Activities at the NASA Marshall Space Flight Center - 2006 Accomplishments

In 2005-06, the Prometheus program funded a number of tasks at the NASA-Marshall Space Flight Center (MSFC) to support development of a Nuclear Thermal Propulsion (NTP) system for future manned exploration missions. These tasks include the following: 1. NTP Design Develop Test & Evaluate (DDT&E) Planning 2. NTP Mission & Systems Analysis / Stage Concepts & Engine Requirements 3. NTP Engine System Trade Space Analysis and Studies 4. NTP Engine Ground Test Facility Assessment 5. Non-Nuclear Environmental Simulator (NTREES) 6. Non-Nuclear Materials Fabrication & Evaluation 7. Multi-Physics TCA Modeling. This presentation is a overview of these tasks and their accomplishments

Ballard, Richard O.↗
NASA NTRS1997

Providing the Persistent Data Storage in a Software Engineering Environment Using Java/COBRA and a DBMS

An investigation was undertaken to build the software foundation for the WHERE (Web-based Hyper-text Environment for Requirements Engineering) project. The TCM (Toolkit for Conceptual Modeling) was chosen as the foundation software for the WHERE project which aims to provide an environment for facilitating collaboration among geographically distributed people involved in the Requirements Engineering process. The TCM is a collection of diagram and table editors and has been implemented in the C++ programming language. The C++ implementation of the TCM was translated into Java in order to allow the editors to be used for building various functionality of the WHERE project; the WHERE project intends to use the Web as its communication back- bone. One of the limitations of the translated software (TcmJava), which militated against its use in the WHERE project, was persistent data management mechanisms which it inherited from the original TCM; it was designed to be used in standalone applications. Before TcmJava editors could be used as a part of the multi-user, geographically distributed applications of the WHERE project, a persistent storage mechanism must be built which would allow data communication over the Internet, using the capabilities of the Web. An approach involving features of Java, CORBA (Common Object Request Broker), the Web, a middle-ware (Java Relational Binding (JRB)), and a database server was used to build the persistent data management infrastructure for the WHERE project. The developed infrastructure allows a TcmJava editor to be downloaded and run from a network host by using a JDK 1.1 (Java Developer's Kit) compatible Web-browser. The aforementioned editor establishes connection with a server by using the ORB (Object Request Broker) software and stores/retrieves data in/from the server. The server consists of a CORBA object or objects depending upon whether the data is to be made persistent on a single server or multiple servers. The CORBA object providing the persistent data server is implemented using the Java progranu-ning language. It uses the JRB to store/retrieve data in/from a relational database server. The persistent data management system provides transaction and user management facilities which allow multi-user, distributed access to the stored data in a secure manner.

Dhaliwal, Swarn S.↗
NASA NTRS1996

My-Star: A Methodology and System for Tracing and Analyzing Requirements

This paper describes a methodology developed at the Jet Propulsion Laboratory (JPL), and designed for the process of requirements engineering and management. MY-STAR provides techniques for specifying, refining, allocating, baselining,sharing, changing, storing, and reporting on requirements and requirements metrics.

MY-STAR requirements engineering requirements mana↗
NASA NTRS1986

Advanced bearing materials for cryogenic aerospace engine turbopump requirements

The properties of eleven alloys were investigated to select an improved bearing material for the High Pressure Oxygen Turbo Pump which delivers liquid oxygen to the Space Shuttle Main Engine. The alloys, selected through detailed literature analysis, X 405, MRC-2001, T440V, 14-4/6V, D-5, V-M Pyromet 350, Stellite 3, FerroTic CS-40, Tribaloy 800, WD-65, and CBS-600. The alloys were tested in hardness, corrosion resistance, wear resistance, fatigue resistance, and fracture toughness tests, and their performance was compared with the baseline 440C test alloy. As a result, five alloys were eliminated, leaving the remaining six (X 405, MRC-2001, T440V, 14-4/6V, D-5, and WD-65 to be evaluated in the next phase of NASA tests which will include fracture toughness, rolling contact fatigue, wear resistance, and corrosion resistance. From these, three alloys will be selected, which will be made into ninety bearings for subsequent testing.

Friedman, G.↗
NASA NTRS1978

Design of a large span-distributed load flying-wing cargo airplane with laminar flow control

A design study was conducted to add laminar flow control to a previously design span-distributed load airplane while maintaining constant range and payload. With laminar flow control applied to 100 percent of the wing and vertical tail chords, the empty weight increased by 4.2 percent, the drag decreased by 27.4 percent, the required engine thrust decreased by 14.8 percent, and the fuel consumption decreased by 21.8 percent. When laminar flow control was applied to a lesser extent of the chord (approximately 80 percent), the empty weight increased by 3.4 percent, the drag decreased by 20.0 percent, the required engine thrust decreased by 13.0 percent, and the fuel consumption decreased by 16.2 percent. In both cases the required take-off gross weight of the aircraft was less than the original turbulent aircraft.

Lovell, W. A.↗