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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 1,567 records · Page 87
All sourcesNASA NTRSDOE OSTI
NASA NTRS1983

Pointing requirements for space station science

It appears that man's next evolutionary step in spaceflight will involve his permanent presence in space with a station in earth orbit. For the purpose of discussing pointing requirements for science and applications studies, a space station with certain characteristics is considered, taking into account a low earth orbit station. It is assumed that the space station will be a system with a permanently manned core facility for conducting science, applications, and technical activities in space. Certain problems can best be solved by utilizing platforms or associated free flying spacecraft which would be part of the space station system, but not part of the space station core. Four classes of pointing requirements are defined, including those which can be satisfied by directly using the space station core, two classes which can be satisfied by gimbal systems, and finally a class which can be satisfied by making use of associated free flying spacecraft or platforms.

Paddack, S. J.↗
NASA NTRS1983

Space Station Control Requirements and Flywheel System Weights for Combined Momentum and Energy Storage

The specifications of the flywheel system for momentum storage and vehicle torquing are somewhat dependent upon the attitude control requirements of the space station in orbit. As a ground rule, the flywheel system will be sized large enough to provide all attitude maneuvers, if practical, to avoid or minimize turning on the reaction control system (RCS). The RCS, whenever used, expels expensive mass and tends to contaminate optical surfaces of the vehicle. The vehicle rate and acceleration specifications of 0.10 deg/sec and 0.01 deg/square sec are tentative, and may be reduced if lesser values are more practical for flywheel design. For local vertical attitude hold, the average attitude error should be zero, and not the classical 1 degree, since control moment gyro (CMG) gimbal angles provide an exact reference feedback for gravity gradient momentum. Docking presents a problem for docking transients and attitude alignment which will require use of the RCS.

Elam, F. M.↗
NASA NTRS1983

Study of auxiliary propulsion requirements for large space systems, volume 2

A range of single shuttle launched large space systems were identified and characterized including a NASTRAN and loading dynamics analysis. The disturbance environment, characterization of thrust level and APS mass requirements, and a study of APS/LSS interactions were analyzed. State-of-the-art capabilities for chemical and ion propulsion were compared with the generated propulsion requirements to assess the state-of-the-art limitations and benefits of enhancing current technology.

Smith, W. W.↗
NASA NTRS1983

A study of the charged particle calibration requirements for the Deep Space Network

A study made of the Deep Space Network charged particle calibration requirements is discussed. The effects of charged particles on navigation and timing systems were reviewed and it was proposed that a system based upon the Global Positioning System satellites be used to measure the charged particle content of the ionosphere. The system would be required to measure the total electron content of the ionosphere to the order of 10 to the 16th power electron per square meter. Two types of systems were suggested as possible candidates for making these measurements.

Townes, S. A.↗
NASA NTRS1984

IMCS reflight certification requirements and design specifications

The requirements for reflight certification are established. Software requirements encompass the software programs that are resident in the PCC, DEP, PDSS, EC, or any related GSE. A design approach for the reflight software packages is recommended. These designs will be of sufficient detail to permit the implementation of reflight software. The PDSS/IMC Reflight Certification system provides the tools and mechanisms for the user to perform the reflight certification test procedures, test data capture, test data display, and test data analysis. The system as defined will be structured to permit maximum automation of reflight certification procedures and test data analysis.

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NASA NTRS1983

Space Station needs, attributes and architectural options. Volume 2, book 1, part 1: Mission requirements

The baseline mission model used to develop the space station mission-related requirements is described as well as the 90 civil missions that were evaluated, (including the 62 missions that formed the baseline model). Mission-related requirements for the space station baseline are defined and related to space station architectural development. Mission-related sensitivity analyses are discussed.

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NASA NTRS1984

Present capabilities and future requirements for computer-aided geometric modeling in the design and manufacture of gas turbine

Gas turbine engine design requires the ability to rapidly develop complex structures which are subject to severe thermal and mechanical operating loads. As in all facets of the aerospace industry, engine designs are constantly driving towards increased performance, higher temperatures, higher speeds, and lower weight. The ability to address such requirements in a relatively short time frame has resulted in a major thrust towards integrated design/analysis/manufacturing systems. These computer driven graphics systems represent a unique challenge, with major payback opportunities if properly conceived, implemented, and applied.

Caille, E.↗
NASA NTRS1984

Design versus manufacturing data base management requirements

Data base management systems are valuable manufacturing and design tools as these disciplines are exceptionally information intensive, requiring precise organization and control of data processing and utilization. One such data base manager is the IPAD* system, which was originally developed to support the design process but was expanded to incorporate the additional needs of manufacturing. To set the stage, an overview of the design and manufacturing process is presented. The different functions of computers in these processes are then discussed. Finally, the design and manufacturing requirements for a data base manager are compared and contrasted.

Mckenna, E. G.↗
NASA NTRS1981

Manned geosynchronous mission requirements and systems analysis study extension

Turnaround requirements for the manned orbital transfer vehicle (MOTV) baseline and alternate concepts with and without a space operations center (SOC) are defined. Manned orbital transfer vehicle maintenance, refurbishment, resupply, and refueling are considered as well as the most effective combination of ground based and space based turnaround activities. Ground and flight operations requirements for abort are identified as well as low cost approaches to space and ground operations through maintenance and missions sensitivity studies. The recommended turnaround mix shows that space basing MOTV at SOC with periodic return to ground for overhaul results in minimum recurring costs. A pressurized hangar at SOC reduces labor costs by approximately 50%.

Source record↗
NASA NTRS1984

New Short Constraint Length, Rate 1/N Convolutional Codes which Minimize Required E Sub B/n Sub o for Given Bit Error Rate

Instead of using the criterion of maximum free distance, (df) or the maximum (df) with minimizing a few first distance profiles, short constraint length rate 1/N convolution codes were searched using a criterion of minimizing required bit energy-to-noise density ratio, E(b)/N(o), for a given value of desired bit error rate (BER), for the goodness of a code. The considered channel was binary antipodal signaling over additive white Gaussian noise and no quantization at the channel output. For the BER calculations, the transfer function bounding technique was used. Partial searches were performed using some known facts and a very useful idea that "good codes generate good codes.'' That is, for a given constraint length K, good rate 1/(N + 1) codes can be found by extending the code generator matrices of good rate 1/N codes. The code search results are tabulated for 3 or = K or = 7 and 2 or = N or = 8. For many pairs of K and N, the new codes are shown to save 0.1 to 0.4 dB in the required E(b)/N(o) compared to previously reported codes. Additionally, the benefits of coding bandwidth expansion are confirmed with the new codes.

Lee, P. J.↗
NASA NTRS1984

Unconventional missile concepts from consideration of varied mission requirements

Missile concepts for volumetric efficiency, minimum carriage constraints, and aerodynamic performance to achieve mission requirements. The mission requirements considered include air to surface roles such as defense suppression or antishipping where payload and range may have priority over high maneuver capability, and air to air and surface to air roles paying attention to good maneuvering capability. The concepts are intended to provide for ease of storage or carriage. The concepts include monoplanes with highly swept, thick delta wings, highly swept delta wings mounted either high or low on a semicircular body, some ring wing and semiring wing arrangements, parasol wing, and elliptical lifting bodies. The missile configurations indicate possible approaches toward resolving problems of carriage and storage while retaining good volumetric and aerodynamic efficiency. The configurations can accomplish a variety of possible missions with relatively simple vehicle shapes.

Spearman, M. L.↗
NASA NTRS1983

A study of space station needs, attributes and architectural options. Volume 2: Technical. Book 1: Mission requirements

The following types of space missions were evaluated to determine those that require, or will be benefited materially, by a manned space station: (1) science and applications, (2) commercial, (3) technology development, (4) space operations, and (5) national security. Integrated mission requirements for man-operated and man-tended free-flying missions were addressed. A manned space station will provide major performance and economic benefits to a wide range of missions planned for the 1990s.

Steinbronn, O.↗
NASA NTRS1983

Space station needs, attributes and architectural options: Mission requirements

Various mission requirements for the proposed space station are examined. Subjects include modelling methodology, science applications, commercial opportunities, operations analysis, integrated mission requirements, and the role of man in space station functions and activities. The information is presented through the use of graphs.

Source record↗
NASA NTRS1982

Facility requirements for helicopter noise research

Development of future helicopter noise prediction methods requires an accurate experimental data base for correlation studies or assessment of theoretical prediction methods. The aerodynamic and acoustic performance criteria for conducting experimental studies of helicopter noise using existing test facilities were defined. Requirements for ground-based facilities were described in addition to the limitations associated with full scale and model scale studies. Flight testing methods were also evaluated briefly and the restrictions associated with these approaches were cited. Finally, a general evaluation of ground-based and flight testing methods is given. Based on this presentation, future investigators can select the experimental approach best suited for generating a desired data base. Also, facility improvements need to extend the state of the art in helicopter noise experimental studies so that problems can be identified.

Schlinker, R. H.↗
NASA NTRS1982

A designer's viewpoint: Requirements for reducing helicopter noise

Functional requirements of helicopter noise reduction are discussed from the work environment point by view, i.e., what conditions must exist before the designer can take aim, without too many restraints, at reducing noise, community demand for noise reduction, regulatory requirements, competition, and penalties are among the topics discussed.

Cohen, E. E.↗