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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 1,153 records · Page 64
All sourcesNASA NTRSDOE OSTI
NASA NTRS1997

Space Shuttle Main Engine Off-Nominal Low Power Level Operation

This paper describes Rocketdyne's successful analysis and demonstration of the Space Shuttle Main Engine (SSME) operation at off-nominal power levels during Reusable Launch Vehicle (RLV) evaluation tests. The nominal power level range for the SSME is from 65% rated power level (RPL) to 109% RPL. Off-nominal power levels incrementally demonstrated were: 17% RPL, 22% RPL, 27% RPL, 40% RPL, 45% RPL, and 50% RPL. Additional achievements during low power operation included: use of a hydrostatic bearing High Pressure Oxidizer Turbopump (HPOTP), nominal High Pressure Fuel Turbopump (HPFTP) first rotor critical speed operation, combustion stability at low power levels, and refined definition of nozzle flow separation heat loads.

Bradley, Michael↗
NASA NTRS1995

Using hob offset to balance dynamic strength in spur gears

This paper presents an analytical study on the effect of hob offset on the dynamic tooth strength of spur gears. The study was limited to equal and opposite offset values applied to the pinion and gear to maintain the standard operating center distance. The analysis presented in this paper was performed using a new version of the NASA gear dynamics code DANST. The operating speed of the transmission has a significant influence on the amount of hob offset required to equalize the dynamic stresses in the pinion and gear. In the transmission studied, at low speeds, the optimum hob offset value was found to fluctuate. At higher speeds, the optimum value was constrained by the minimum allowed thickness at the tip of the pinion tooth. For gears that must operate over a range of speeds, an average offset value may be used. Spur gears designed with the procedure presented here can have significant improvements in load capacity.

Liou, Chuen-Huei↗
NASA NTRS2002

Variable Order and Distributed Order Fractional Operators

Many physical processes appear to exhibit fractional order behavior that may vary with time or space. The continuum of order in the fractional calculus allows the order of the fractional operator to be considered as a variable. This paper develops the concept of variable and distributed order fractional operators. Definitions based on the Riemann-Liouville definitions are introduced and behavior of the operators is studied. Several time domain definitions that assign different arguments to the order q in the Riemann-Liouville definition are introduced. For each of these definitions various characteristics are determined. These include: time invariance of the operator, operator initialization, physical realization, linearity, operational transforms. and memory characteristics of the defining kernels. A measure (m2) for memory retentiveness of the order history is introduced. A generalized linear argument for the order q allows the concept of "tailored" variable order fractional operators whose a, memory may be chosen for a particular application. Memory retentiveness (m2) and order dynamic behavior are investigated and applications are shown. The concept of distributed order operators where the order of the time based operator depends on an additional independent (spatial) variable is also forwarded. Several definitions and their Laplace transforms are developed, analysis methods with these operators are demonstrated, and examples shown. Finally operators of multivariable and distributed order are defined in their various applications are outlined.

Lorenzo, Carl F.↗
NASA NTRS1972

A Critique of Cab Regulatory Policy

The regulatory policies of the Civil Aviation Board are discussed. The objectives of the Civil Aviation Board are defined. Specific actions of the Civil Aviation Board with respect to passenger fares, rate levels, and load factors are presented. The decisions on successful and unsuccessful mergers of airlines during the 1938 to 1972 time period are analyzed. Tables of data are presented to show the economic aspects of airline operations during 1955, 1960, and 1970.

management methods↗
NASA NTRS1981

The pacific northwest remote sensing project

The history of a 3-year effort in Idaho, Oregon, and Washington to establish operational capabilities to analyze LANDSAT digital data and apply the results to natural resources management programs is related. Currently a number of agencies are conduct operational applications projects utilizing the data analysis facilities available and LANDSAT-derived data are being used by these agencies in their day-to-day operations. The image analysis systems and software used in each state are described and the participating state and local agencies are listed.

Hedrick, W. E.↗
NASA NTRS1983

Proposed study to determine potential flight applications and human factors design guidelines of voice recognition/synthesis systems

An effort to evaluate the human factors aspects and potential of voice recognition/synthesis techniques and the application of present and near-future (5 years) voice recognition/synthesis systems as a pilot/aircraft cockpit interface capability in an operational environment is discussed. The analysis will emphasize applications for single pilot instrument flight rules operations but will also include applications for other categories of aircraft with various levels of complexity.

Bergeron, H. P.↗
NASA NTRS1993

Active magnetic bearings applied to industrial compressors

The design and shop test results are given for a high-speed eight-stage centrifugal compressor supported by active magnetic bearings. A brief summary of the basic operation of active magnetic bearings and the required rotor dynamics analysis are presented with specific attention given to design considerations for optimum rotor stability. The concerns for retrofits of magnetic bearings in existing machinery are discussed with supporting analysis of a four-stage centrifugal compressor. The current status of industrial machinery in North America using this new support system is presented and recommendations are given on design and analysis requirements for successful machinery operation of either retrofit or new design turbomachinery.

Kirk, R. G.↗
NASA NTRS2015

Technical Challenges and Opportunities of Centralizing Space Science Mission Operations (SSMO) at NASA Goddard Space Flight Center

The NASA Goddard Space Science Mission Operations project (SSMO) is performing a technical cost-benefit analysis for centralizing and consolidating operations of a diverse set of missions into a unified and integrated technical infrastructure. The presentation will focus on the notion of normalizing spacecraft operations processes, workflows, and tools. It will also show the processes of creating a standardized open architecture, creating common security models and implementations, interfaces, services, automations, notifications, alerts, logging, publish, subscribe and middleware capabilities. The presentation will also discuss how to leverage traditional capabilities, along with virtualization, cloud computing services, control groups and containers, and possibly Big Data concepts.

Science↗
NASA NTRS2016

End-to-End Trajectory for Conjunction Class Mars Missions Using Hybrid Solar-Electric/Chemical Transportation System

NASA's Human Spaceflight Architecture Team is developing a reusable hybrid transportation architecture in which both chemical and solar-electric propulsion systems are used to deliver crew and cargo to exploration destinations. By combining chemical and solar-electric propulsion into a single spacecraft and applying each where it is most effective, the hybrid architecture enables a series of Mars trajectories that are more fuel efficient than an all chemical propulsion architecture without significant increases to trip time. The architecture calls for the aggregation of exploration assets in cislunar space prior to departure for Mars and utilizes high energy lunar-distant high Earth orbits for the final staging prior to departure. This paper presents the detailed analysis of various cislunar operations for the EMC Hybrid architecture as well as the result of the higher fidelity end-to-end trajectory analysis to understand the implications of the design choices on the Mars exploration campaign.

Chai, Patrick R.↗
NASA NTRS1994

Gear tooth topological modification

The topology of parallel axis gears, such as spur and helical gears is modified to produce quieter and more smoothly operating gear sets with more uniform load distribution. A finite element analysis of the gear in its operating mode is made to produce a plot of radial and tangential deflections of the pinion and gear tooth surfaces which will occur when the gears are loaded during operation. The resultant plot is then inverted to produce a plot, or set of coordinates, which will define the path of travel of the gear tooth grinding wheel, which path is a mirror image of the plot of the finite element analysis. The resulting gears, when subjected to operating loads, will thus be deflected tangentially and radially to their optimum operating, or theoretical true involute, positions so as to produce quieter, smoother, and more evenly loaded gear trains.

Kish, Jules G.↗
NASA NTRS2001

The ATIC Experiment: First Balloon Flight

The Advanced Thin Ionization Calorimeter (ATIC) Balloon Experiment had its maiden, test, flight from McMurdo, Antarctica 28/12/00 to 13/01/01, local time, recording over 360 hours of data. ATIC was designed to measure the composition and energy spectra of cosmic rays from approximately 10 GeV to near 100 TeV utilizing a Si-matrix detector to determine charge in conjunction with a scintillator hodoscope which measures charge and trajectory. Cosmic rays that interact in a Carbon target have their energy determined from the shower that develops within a fully active calorimeter composed of a stack of scintillating BGO crystals. ATIC's geometry factor is about 0.25 m**2-sr. During line-of-sight operations much of the datastream was transmitted to the ground. For most of the flight, the data was recorded on-board, yielding 45 GB of flight data for analysis. The payload construction, operations and in-flight performance are described, along with preliminary results from the on-going analysis.

Wefel, J. P.↗
NASA NTRS2001

The ATIC Experiment: First Balloon Flight

The Advanced Thin Ionization Calorimeter (ATIC) Balloon Experiment had its maiden test flight from McMurdo, Antarctica 28/12/00 to 13/01/01, local time, recording over 360 hours of data. ATIC was designed to measure the composition and energy spectra of cosmic rays from approx. 10 GeV to near 100 TeV utilizing a Si matrix detector to determine charge in conjunction with a scintillator hodoscope which measures charge and trajectory. Cosmic rays that interact in a carbon target have their energy determined from the shower that develops within a fully active calorimeter composed of a stack of scintillating BGO (Bismuth Germanate) crystals. ATIC's geometry factor is about 0.25 sq. m -sr. During line-of-sight operations much of the datastream was transmitted to the ground. For most of the flight, the data was recorded on-board, yielding 45 GB of flight data for analysis. The payload construction, operations and in-flight performance are described, along with preliminary results from the on-going analysis.

Wefel, J. P.↗
NASA NTRS1980

Geostationary platform systems concepts definition study. Volume 2: Technical, book 1

The initial selection and definition of operational geostationary platform concepts is discussed. Candidate geostationary platform missions and payloads were identified from COMSAT, Aerospace, and NASA studies. These missions and payloads were cataloged; classified with to communications, military, or scientific uses; screened for application and compatibility with geostationary platforms; and analyzed to identify platform requirements. Two platform locations were then selected (Western Hemisphere - 110 deg W, and Atlantic - 15 deg W), and payloads allocated based on nominal and high traffic models. Trade studies were performed leading to recommendation of selected concepts. Of 30 Orbit Transfer Vehicle (0TV) configuration and operating mode options identified, 18 viable candidates compatible with the operational geostationary platform missions were selected for analysis. Each was considered using four platform operational modes - 8 or 16 year life, and serviced or nonserviced, providing a total of 72 OTV/platform-mode options. For final trade study concept selection, a cost program was developed considering payload and platform costs and weight; transportation unit and total costs for the shuttle and OTV; and operational costs such as assembly or construction time, mating time, and loiter time. Servicing costs were added for final analysis and recommended selection.

Source record↗
NASA NTRS1982

An advanced tracker design for pointing and control of space vehicles using the charge injection device

The use of charge transfer devices (CTD) in pointing and control of space vehicles is examined, with emphasis on the use of charge injection devices (CID). The selection of CTD type and CID operation, including CID signal and noise analysis and signal improvement, are discussed. Star tracking operational advantages of the CTD are pointed out, and the tracking optical concept is discussed and graphically depicted. The position interpolation procedure and the effects of rate of stellar motion on position interpolation are considered, and error analysis is examined. Finally, the breadboard and test program are discussed in detail, coarse and fine acquisition, test for star, track pattern, test procedure and results. An overall accuracy performance of approximately 0.02 pixels or approximately 0.8 arcsec for the test equipment and tracker was obtained.

Jones, C.↗
NASA NTRS1974

Shuttle user analysis (study 2.2): Volume 3. Business Risk And Value of Operations in space (BRAVO). Part 4: Computer programs and data look-up

Computer program listings as well as graphical and tabulated data needed by the analyst to perform a BRAVO analysis were examined. Graphical aid which can be used to determine the earth coverage of satellites in synchronous equatorial orbits was described. A listing for satellite synthesis computer program as well as a sample printout for the DSCS-11 satellite program and a listing of the symbols used in the program were included. The APL language listing for the payload program cost estimating computer program was given. This language is compatible with many of the time sharing remote terminals computers used in the United States. Data on the intelsat communications network was studied. Costs for telecommunications systems leasing, line of sight microwave relay communications systems, submarine telephone cables, and terrestrial power generation systems were also described.

Source record↗
NASA NTRS2011

Multidisciplinary Tool for Systems Analysis of Planetary Entry, Descent, and Landing

Systems analysis of a planetary entry (SAPE), descent, and landing (EDL) is a multidisciplinary activity in nature. SAPE improves the performance of the systems analysis team by automating and streamlining the process, and this improvement can reduce the errors that stem from manual data transfer among discipline experts. SAPE is a multidisciplinary tool for systems analysis of planetary EDL for Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Titan. It performs EDL systems analysis for any planet, operates cross-platform (i.e., Windows, Mac, and Linux operating systems), uses existing software components and open-source software to avoid software licensing issues, performs low-fidelity systems analysis in one hour on a computer that is comparable to an average laptop, and keeps discipline experts in the analysis loop. SAPE uses Python, a platform-independent, open-source language, for integration and for the user interface. Development has relied heavily on the object-oriented programming capabilities that are available in Python. Modules are provided to interface with commercial and government off-the-shelf software components (e.g., thermal protection systems and finite-element analysis). SAPE currently includes the following analysis modules: geometry, trajectory, aerodynamics, aerothermal, thermal protection system, and interface for structural sizing.

Samareh, Jamshid A.↗