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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 361 records · Page 20

All sources NASA NTRS DOE OSTI

NASA NTRS1976

Mission planning, mission analysis and software formulation. Level C requirements for the shuttle mission control center orbital guidance software

The formulation of Level C requirements for guidance software was reported. Requirements for a PEG supervisor which controls all input/output interfaces with other processors and determines which PEG mode is to be utilized were studied in detail. A description of the two guidance modes for which Level C requirements have been formulated was presented. Functions required for proper execution of the guidance software were defined. The requirements for a navigation function that is used in the prediction logic of PEG mode 4 were discussed. It is concluded that this function is extracted from the current navigation FSSR.

Langston, L. J.↗

NASA NTRS1975

Analysis of navigation and guidance requirements for commercial VTOL operations

The paper presents some results of a program undertaken to define navigation and guidance requirements for commercial VTOL operations in the takeoff, cruise, terminal and landing phases of flight in weather conditions up to and including Category III. Quantitative navigation requirements are given for the parameters range, coverage, operation near obstacles, horizontal accuracy, multiple landing aircraft, multiple pad requirements, inertial/radio-inertial requirements, reliability/redundancy, update rate, and data link requirements in all flight phases. A multi-configuration straw-man navigation and guidance system for commercial VTOL operations is presented. Operation of the system is keyed to a fully automatic approach for navigation, guidance and control, with pilot as monitor-manager. The system is a hybrid navigator using a relatively low-cost inertial sensor with DME updates and MLS in the approach/departure phases.

Hoffman, W. C.↗

NASA NTRS1978

OFT ascent/descent ancillary data requirements document

Requirements are presented for the ascent/descent (A/D) navigation and attitude-dependent ancillary data products to be generated for the space shuttle orbiter in support of orbital flight test requirements, MPAD guidance and navigation performance assessment, and the mission evaluation team. It was intended that this document serve as the sole requirements control instrument between MPB/MPAD and the A/D ancillary data users. The requirements are primarily functional in nature, but some detail level requirements are also included.

Bond, A. C., Jr.↗

NASA NTRS1979

Similitude requirements and scaling relationships as applied to model testing

The similitude requirements for the most general test conditions are presented. These similitude requirements are considered in relation to the scaling relationships, test technique, test conditions (including supersonic flow), and test objectives. Particular emphasis is placed on satisfying the various similitude requirements for incompressible and compressible flow conditions. For free flying models tests, the test velocities for incompressible flow are scaled from Froude number similitude requirements and those for compressible flow are scaled from Mach number similitude requirements. The limitations of various test techniques are indicated, with emphasis on the free flying model.

Wolowicz, C. H.↗

NASA NTRS1979

Manned Orbital Transfer Vehicle (MOTV). Volume 3: Program requirements documents

The requirements for geosynchronous orbit capability using the manned orbit transfer vehicle (MOTV) are defined. The program requirements, the mission requirements, and the system and subsystem requirements for the MOTV are discussed. The mission requirements include a geosynchronous Earth orbit vehicle for the construction, servicing, repair and operation of communications, solar power, and Earth observation satellites.

Boyland, R. E.↗

NASA NTRS1980

Shuttle program. MCC Level C formulation requirements: Entry guidance and entry autopilot

A set of preliminary entry guidance and autopilot software formulations is presented for use in the Mission Control Center (MCC) entry processor. These software formulations meet all level B requirements. Revision 2 incorporates the modifications required to functionally simulate optimal TAEM targeting capability (OTT). Implementation of this logic in the MCC must be coordinated with flight software OTT implementation and MCC TAEM guidance OTT. The entry guidance logic is based on the Orbiter avionics entry guidance software. This MCC requirements document contains a definition of coordinate systems, a list of parameter definitions for the software formulations, a description of the entry guidance detailed formulation requirements, a description of the detailed autopilot formulation requirements, a description of the targeting routine, and a set of formulation flow charts.

Harpold, J. C.↗

NASA NTRS1950

Investigation of Power Requirements for Ice Prevention and Cyclical De-Icing of Inlet Guide Vanes with Internal Electric Heaters

An investigation was conducted to determine the electric power requirements necessary for ice protection of inlet guide vanes by continuous heating and by cyclical de-icing. Data are presented to show the effect of ambient-air temperature, liquid-water content, air velocity, heat-on period, and cycle times on the power requirements for these two methods of ice protection. The results showed that for a hypothetical engine using 28 inlet guide vanes under similar icing conditions, cyclical de-icing can provide a total power saving as high as 79 percent over that required for continuous heating. Heat-on periods in the order of 10 seconds with a cycle ratio of about 1:7 resulted in the best over-all performance with respect to total power requirements and aerodynamic losses during the heat-off period. Power requirements reported herein may be reduced by as much as 25 percent by achieving a more uniform surface-temperature distribution. A parameter in terms of engine mass flow, vane size, vane surface temperature, and the icing conditions ahead of the inlet guide vanes.was developed by which an extension of the experimental data to icing conditions and inlet guide vanes, other than those investigated was possible.

VonGlahn, Uwe↗

NASA NTRS1982

Precise time and time interval users, requirements and specifications

The functional areas of application of Precise Time and Time Interval (PTTI) were considered and expanded. A comprehensive overview of the PTTI requirements and applications would provide an opportunity for individuals working in a specific functional area. Mutual problems, requirements, applications or successes shared by those in other functional areas were studied. Based upon the results of a two year study a compendium of PTTI requirements, applications and the means of meeting the requirements among Department of Defense components, other government agencies and major commercial users was compiled and is presented. It was found that the planning process for PTTI support for new acquisitions or new programs was less than a well defined, coordinated process. The processes are described in general terms and a generic model for requirements determination and subsequent coordination which may enhance the planning process and introduce cost benefits to the program is also presented.

Bowser, J. R.↗

NASA NTRS1986

Orbital transfer vehicle launch operations study: Manpower summary and facility requirements, volume 5

All manpower numbers, number of heads (by skill), serial time and manhours have been accumulated and compiled on a per subtask basis in spreadsheet format for both the ground based and the space based data flows. To aid in identifying the facility resources required to process the Ground Based Orbital Transfer Vehicle (GBOTV) and/or the space based orbital transfer vehicle (SBOTV) through the ground facilities at Kennedy Space Center (KSC), a software application package was developed using a general purpose data base management system known as Data Flex. The facility requirements are used as the basic input to this software application. The resources of the KSC facility that could be used by orbital transfer vehicle program were digitized in the same format used to identify facility requirements. The facility capabilities were digitized in this format for subsequent, automated comparative analyses. Composite facility requirements are compared to each of the baseline facility capabilities and the system generates a relative score that indicates how each facility weighs against the composite requirements in relation to the other facilities in the set.

Source record↗

NASA NTRS1987

The JPL functional requirements tool

Planetary spacecraft are complex vehicles which are built according to many thousands of requirements. Problems encountered in documenting and maintaining these requirements led to the current attempt to reduce or eliminate these problems by a computer automated data base Functional Requirements Tool. The tool developed at JPL and in use on several JPL Projects is described. The organization and functionality of the Tool, together with an explanation of the data base inputs, their relationships, and use are presented. Methods of interfacing with external documents, representation of tables and figures, and methods of approval and change processing are discussed. The options available for disseminating information from the Tool are identified. The implementation of the Requirements Tool is outlined, and the operation is summarized. The conclusions drawn from this work is that the Requirements Tool represents a useful addition to the System Engineer's Tool kit, it is not currently available elsewhere, and a clear development path exists to expand the capabilities of the Tool to serve larger and more complex projects.

Giffin, Geoff↗

NASA NTRS1988

Advanced EVA system design requirements study

The results are presented of a study to identify specific criteria regarding space station extravehicular activity system (EVAS) hardware requirements. Key EVA design issues include maintainability, technology readiness, LSS volume vs. EVA time available, suit pressure/cabin pressure relationship and productivity effects, crew autonomy, integration of EVA as a program resource, and standardization of task interfaces. A variety of DOD EVA systems issues were taken into consideration. Recommendations include: (1) crew limitations, not hardware limitations; (2) capability to perform all of 15 generic missions; (3) 90 days on-orbit maintainability with 50 percent duty cycle as minimum; and (4) use by payload sponsors of JSC document 10615A plus a Generic Tool Kit and Specialized Tool Kit description. EVA baseline design requirements and criteria, including requirements of various subsystems, are outlined. Space station/EVA system interface requirements and EVA accommodations are discussed in the areas of atmosphere composition and pressure, communications, data management, logistics, safe haven, SS exterior and interior requirements, and SS airlock.

Woods, T. G.↗

NASA NTRS1989

Science requirements for passive microwave sensors on earth science geostationary platforms

It is suggested that the science requirements for passive geostationary microwave observations be met by near- and far-term sensors for each of two overlapping bands, with each band covering no more than a decade in frequency. The low-frequency band includes channels near 6, 10, 18, 22, 31 to 37, and possibly 50 to 60 GHz. The high-frequency band includes channels near 220 to 230, 183, 166, 118, 90 to 110, and possibly 50 to 60 and 31 to 37 GHz. The precise channel specifications will have to comply with international frequency allocations. The near-term goal is a high-frequency sensor based on a filled-aperture solid reflector antenna, which should rely on currently existing technology. The most critical issues for the near-term sensor are momentum compensation and the design of the feed assembly; these issues are coupled through the desired scan rate. The successful demonstration of the near-term (high-frequency) sensor will be essential for the continued development of far-term sensors satisfying the ideal science requirements. The far-term goal includes both a high-frequency sensor which meets the ideal science requirements, and a low-frequency sensor whose design will depend on advances in large antenna technology. The low-frequency (far-term) sensor might be based on one of several concepts: a deployable mesh reflector antenna of diameter at least 20 m, which shows promise for use at frequencies up to 30-GHz, a synthetic aperture interferometer of maximum baseline from 100 to 300 m, or a deployable phased-array bootlace lens, of diameter from 100 to 300 m. The first of these, a deployable mesh reflector antenna, will satisfy only the adequate spatial resolution requirements. The last two concepts meet the ideal spatial resolution science requirements, although they present significant structural and meteorological challenges.

Gasiewski, A. J.↗

NASA NTRS1990

Aerodynamic requirements of a manned Mars aerobraking transfer vehicle

In this investigation, entry corridor analyses are performed to identify the aerodynamic requirements of a manned Mars aerobraking transfer vehicle. The major emphasis is on identifying the required aerobrake hypersonic L/D to insure a successful aerocapture. Aerobraking entry requirements are also imposed on a set of interplanetary mission opportunities to demonstrate their effect on mission flexibility. Based on the requirements of a 1 deg corridor width, deceleration into a parking orbit witn an apoapsis altitude of 32,972 km, and a 5-g deceleration limit, a manned Mars aerobrake characterized by an L/D of at least 1.5 is required for entry velocities as high as 10.0 km/sec. Limiting the Mars entry velocity to values below 8.5 km/sec is shown to induce a minor restriction on mission flexibility while alleviating aerothermodynamic and vehicle packaging concerns; hence, Mars entry velocities in the range of 6.0-8.5 km/sec are suggested, and a manned Mars aerobrake characterized by an L/D between 0.3 and 0.5 is recommended.

Braun, Robert D.↗

NASA NTRS1990

NASA's future space power needs and requirements

The National Space Policy of 1988 established the U.S.'s long-range civil space goals, and has served to guide NASA's recent planning for future space mission operations. One of the major goals was to extend the human presence beyond earth's boundaries and to advance the scientific knowledge of the solar system. A broad spectrum of potential civil space mission opportunities and interests are currently being investigated by NASA to meet the espoused goals. Participation in many of these missions requires power systems with capabilities far beyond what exists today. In other mission examples, advanced power systems technology could enhance mission performance significantly. Power system requirements and issues that need resolution to ensure eventual mission accomplishment are addressed, in conjunction with the ongoing NASA technology development efforts and the need for even greater innovative efforts to match the ambitious solar exploration mission goals. Particular attention is given to potential lunar surface operations and technology goals, based on investigations to date. It is suggested that the nuclear reactor power systems can best meet long-life requirements as well as dramatically reduce the earth-surface-to-lunar-surface transportation costs due to the lunar day/night cycle impact on the solar system's energy storage mass requirements. The state of the art of candidate power systems and elements for the lunar application and the respective exploration technology goals for mission life requirements from 10 to 25 years are examined.

Schnyer, A. D.↗

NASA NTRS1991

Using adaptive structures to enable future missions by relaxing ground test requirements

Future NASA missions will require large space structures that must maintain accurate surface tolerances for up to 20 years; most flight programs require a ground test verification of the hardware. Because of the influence of gravity, the current state-of-the-art ground test technology cannot accurately determine whether the hardware complies with the requirements. The incorporation of adaptive structures into the spacecraft will enable a relaxation of the ground test requirements necessary to validate the hardware for flight. This paper describes the challenges in testing large precision structures, adaptive structures, the data establishing the current state of the art in ground testing, and the utilization of adaptive structures to alleviate the ground test requirements.

Wada, Ben K.↗

NASA NTRS1991

Determining the IV fluids required for a ten day medical emergency on Space Station Freedom - Comparison of packaged vs. on-orbit produced solutions

To aid planning for the storage of supplies onboard Space Station Freedom, an estimate was made of the amount of intravenous (IV) fluid required to support a patient who has suffered a medical emergency for a period of up to 10 days. Six different medical scenarios were evaluated, and the volume of IV fluids required for each scenario was estimated. Up to 220 liters of fluid would be required to support a patient for all of the scenarios. When optimizing the volumes to support any single scenario, a total of 123 liters is required. Use of a water polishing system to produce sterile water for injection from potable supplies and on-station formulation of IV fluids results in a smaller mass and volume requirement for the Fluid Therapy Subsystem than carrying prepackaged bags of fluid.

Creager, Gerald J.↗

NASA NTRS1991

A tailored approach to electromagnetic compatibility requirements in space applications

An approach is outlined which defines the requirements for electromagnetic compatibility (EMC) between NASA and military technologies with attention given to electromagnetic interference (EMI) requirements. In order to minimize the cost and weight impact of the changes needed for compatibility the plan emphasizes the incorporation of off-the-shelf technology with current nonstandard methods. NASA designs are structured to meet EMI requirements rather than processing waivers against military-type specifications. The NASA-wide EMI requirements can be documented in three sections: requirements, test methods, and tailoring guidelines. It is shown that a NASA-wide EMC specification would decrease the costs of achieving compatibility by increasing efficiency and optimizing the relationship between EMC design and performance and cost.

Javor, Ken↗

NASA NTRS1992

NSPWG-recommended safety requirements and guidelines for SEI nuclear propulsion

An interagency Nuclear Safety Policy Working Group (NSPWG) was chartered to recommend nuclear safety policy, requirements, and guidelines for the Space Exploration Initiative (SEI) nuclear propulsion program to facilitate the implementation of mission planning and conceptual design studies. The NSPWG developed a top-level policy to provide the guiding principles for the development and implementation of the nuclear propulsion safety program and the development of safety functional requirements. In addition, the NSPWG reviewed safety issues for nuclear propulsion and recommended top-level safety requirements and guidelines to address these issues. Safety requirements were developed for reactor start-up, inadvertent criticality, radiological release and exposure, disposal, entry, and safeguards. Guidelines were recommended for risk/reliability, operational safety, flight trajectory and mission abort, space debris and meteoroids, and ground test safety. In this paper the specific requirements and guidelines will be discussed.

Marshall, Albert C.↗