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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 523 records · Page 29
All sourcesNASA NTRSDOE OSTI
NASA NTRS1989

Effect of reduced aft diameter and increased blade number of high-speed counterrotation propeller performance

Performance data of 0.17-scale model counterrotation pusher propeller configurations were taken in the NASA Lewis 8- by 6-Foot Supersonic Wind Tunnel at Mach numbers of 0.66, 0.71, 0.75, and 0.79. These tests investigated the aerodynamic performance of the unducted fan (UDF) demonstrator propeller engine developed in a joint program by General Electric and NASA. Data were recorded to show the effect on counterrotation propeller cruise efficiency of two takeoff noise-reduction concepts. These two concepts are reduced aft blade diameter and increased forward blade number. The four configurations tested were a baseline (F1/A1 8/8) configuration, a reduced aft diameter (F1/A3 8/8) configuration, an increase forward blade number (F1/A1 9/8) configuration, and a combination of the latter two (F1/A3 9/8) configurations. Data were collected with a complex counterrotation propeller test rig via rotating thrust and torque balances and pressure instrumentation. Data comparisons documented the power differences between the baseline and the reduced aft diameter concepts. Performance comparisons to the baseline configuration showed that reducing the aft blade diameter reduced the net efficiency, and adding a blade to the front rotor increased the net efficiency. The combination of the two concepts showed only slightly lower net efficiency than the baseline configuration. It was also found that the counterrotation demonstrator propeller model (F7/A7 8/8) configuration outperformed the baseline (F1/A1 8/8) configuration.

Gayle, E. Rose↗
NASA NTRS1976

Results of Skylab experiment T00-2, manual navigation sightings

An analysis of navigation data collected using a hand-held space sextant on the second and third manned Skylab missions was presented. From performance data and astronaut comments it was determined that: (1) the space sextant, the sighting station, and the sighting techniques require modification; (2) the sighting window must be of good optical quality; (3) astronaut performance was stable over long mission time; and (4) sightings made with a hand-held sextant were accurate and precise enough for reliable interplanetary manual navigation.

Randle, R. J.↗
NASA NTRS1988

Airborne Visible/Infrared Imaging Spectrometer (AVIRIS): Inflight radiometric calibration and the determination of surface reflectance

The inflight radiometric performance of AVIRIS is presented together with a comparison of methods of recovering surface spectral reflectance from the data. Performance is evaluated by comparing radiance predicted from AVIRIS with radiance generated from the LOWIRAN 6 atmospheric model and measured surface reflectance. Comparisons show apparent agreement to within a few percent between 1800 and 2450 nm. Between 600 and 1800 nm the response of AVIRIS is systematically low by as much as 70 percent, and between 400 and 600 nm it is higher than expected. These problems are traced to thermal distortions of the instrument, and to detachment during flight of optical fibers connecting foreoptics to two of four spectrometers in the instrument. Of three methods studied, an empirical one involving calibration curves constructed from field reflectance measurements returns accurate predictions of the surface reflectance independent of the actual radiometric significance of the flight data.

Conel, J. E.↗
NASA NTRS2001

Linking Science Analysis with Observation Planning: A Full Circle Data Lifecycle

A clear goal of the Virtual Observatory (VO) is to enable new science through analysis of integrated astronomical archives. An additional and powerful possibility of the VO is to link and integrate these new analyses with planning of new observations. By providing tools that can be used for observation planning in the VO, the VO will allow the data lifecycle to come full circle: from theory to observations to data and back around to new theories and new observations. The Scientist's Expert Assistant (SEA) Simulation Facility (SSF) is working to combine the ability to access existing archives with the ability to model and visualize new observations. Integrating the two will allow astronomers to better use the integrated archives of the VO to plan and predict the success of potential new observations more efficiently, The full circle lifecycle enabled by SEA can allow astronomers to make substantial leaps in the quality of data and science returns on new observations. Our paper examines the exciting potential of integrating archival analysis with new observation planning, such as performing data calibration analysis on archival images and using that analysis to predict the success of new observations, or performing dynamic signal-to-noise analysis combining historical results with modeling of new instruments or targets. We will also describe how the development of the SSF is progressing and what have been its successes and challenges.

Grosvenor, Sandy↗
NASA NTRS2016

Mars 2020 Entry, Descent and Landing Instrumentation (MEDLI2)

This paper will introduce Mars Entry Descent and Landing Instrumentation (MEDLI2) on NASA's Mars2020 mission. Mars2020 is a flagship NASA mission with science and technology objectives to help answer questions about possibility of life on Mars as well as to demonstrate technologies for future human expedition. Mars2020 is scheduled for launch in 2020. MEDLI2 is a suite of instruments embedded in the heatshield and backshell thermal protection systems of Mars2020 entry vehicle. The objectives of MEDLI2 are to gather critical aerodynamics, aerothermodynamics and TPS performance data during EDL phase of the mission. MEDLI2 builds up the success of MEDLI flight instrumentation on Mars Science Laboratory mission in 2012. MEDLI instrumentation suite measured surface pressure and TPS temperature on the heatshield during MSL entry into Mars. MEDLI data has since been used for unprecedented reconstruction of aerodynamic drag, vehicle attitude, in-situ atmospheric density, aerothermal heating, transition to turbulence, in-depth TPS performance and TPS ablation. [1,2] In addition to validating predictive models, MEDLI data has highlighted extra margin available in the MSL forebody TPS, which can potentially be used to reduce vehicle parasitic mass. MEDLI2 expands the scope of instrumentation by focusing on quantities of interest not addressed in MEDLI suite. The type the sensors are expanded and their layout on the TPS modified to meet these new objectives. The paper will provide key motivation and governing requirements that drive the choice and the implementation of the new sensor suite. The implementation considerations of sensor selection, qualification, and demonstration of minimal risk to the host mission will be described. The additional challenges associated with mechanical accommodation, electrical impact, data storage and retrieval for MEDLI2 system, which extends sensors to backshell will also be described.

Thermal Protection System↗
NASA NTRS1972

Evaluation of electroexplosive devices by nondestructive test techniques and impulsive waveform firings

Special requirements of the space industry for more detailed knowledge of the quality and reliability of each electroexplosive device (EED) selected for use aboard a spacecraft are described. Statistical methods do not practically demonstrate the high reliability needed. To close this gap, nondestructive test techniques and instrumentation for 1-W/1-A no-fire devices have been developed. Several lots of squibs have been evaluated using these techniques and instrumentation. They yield data as to the quality and normal behavior of each electroexplosive device without firing or degrading the unit. Performance data were obtained by initiating the EED's with an impulsive waveform and sensing the initiation characteristics, sensitivity, and output.

Menichelli, V. J.↗
NASA NTRS1972

Generation of NEP heliocentric trajectory data

A study, designed to generate representative nuclear electric propulsion data for rendezvous missions to the comet Encke using the variational calculus program HILTOP, is presented. Other purposes of the study include a comparison of the HILTOP data with equivalent data generated with QUICKTOP program and to propose approaches for storing and subsequently accessing the optimum trajectory and performance data in the QUICKLY program.

Horsewood, J. L.↗
NASA NTRS1978

Noise characteristics of upper surface blown configurations: Analytical Studies

Noise and flow results of upper surface blown configurations were analyzed. The dominant noise source mechanisms were identified from experimental data. From far-field noise data for various geometric and operational parameters, an empirical noise prediction program was developed and evaluated by comparing predicted results with experimental data from other tests. USB aircraft compatibility studies were conducted using the described noise prediction and a cruise performance data base. A final design aircraft was selected and theory was developed for the noise from the trailing edge wake assuming it as a highly sheared layer.

Reddy, N. N.↗
NASA NTRS1985

Atomization and Mixing Study

The primary objective was the obtainment of atomization and mixing performance data for a variety of typical liquid oxygen/hydrocarbon injector element designs. Such data are required to establish injector design criteria and to provide critical inputs to liquid rocket engine combustor performance and stability analysis, and computational codes and methods. Deficiencies and problems with the atomization test equipment were identified, and action initiated to resolve them. Test results of the gas/liquid mixing tests indicated that an assessment of test methods was required. A series of 71 liquid/liquid tests were performed.

Ferrenberg, A.↗
NASA NTRS1986

Training and subjective workload in a category search task

This study examined automaticity as a means by which training influences mental workload. Two groups were trained in a category search task. One group received a training paradigm designed to promote the development of automaticity; the other group received a training paradigm designed to prohibit it. Resultant performance data showed the expected improvement as a result of the development of automaticity. Subjective workload assessments mirrored the performance results in most respects. The results supported the position that subjective mental workload assessments may be sensitive to the effect of training when it produces a lower level of cognitive load.

Vidulich, Michael A.↗
NASA NTRS1993

Performance of a low-power subsonic-arc-attachment arcjet thruster

A subsonic-arc-attachment thruster design was scaled from a 30 kW 1960's vintage thruster to operate at nominally 3 kW. Performance measurements were obtained over a 1-4 kW power range using hydrogen as the propellant. Several modes of operation were identified and were characterized by varying degrees of voltage instability. A stability map was developed showing that the voltage oscillations were brought upon by elevated current or propellant levels. At a given specific energy level the specific impulse increased asymptotically with increased flow rates. Comparisons of performance were made between radial and tangential propellant injection. When the vortex flow was eliminated using radial injection, the operating voltages were lower at a given current, and the specific impulse and efficiency decreased. Tests were also conducted to determine the effects of background pressure on operation. Performance data were obtained at pressures of 0.047 Pa and 18 Pa. For a given specific energy level, the performance increased with a decrease in facility background pressure. Lowering the background pressure also caused a dramatic change in the voltage-current characteristic and the voltage stability, a phenomenon not previously reported with conventional supersonic-arc-attachment thrusters.

Sankovic, John M.↗
NASA NTRS1993

Performance of a low-power subsonic-arc-attachment arcjet thruster

A subsonic-arc-attachment thruster design was scaled from a 30 kW 1960's vintage thruster to operate at nominally 3 kW. Performance measurements were obtained over a 1-4 kW power range using hydrogen as the propellant. Several modes of operation were identified and were characterized by varying degrees of voltage instability. A stability map was developed showing that the voltage oscillations were brought upon by elevated current or propellant levels. At a given specific energy level the specific impulse increased asymptotically with increased flow rates. Comparisons of performance were made between radial and tangential propellant injection. When the vortex flow was eliminated using radial injection, the operating voltages were lower at a given current, and the specific impulse and efficiency decreased. Tests were also conducted to determine the effects of background pressure on operation, and performance data were obtained at pressures of 0.047 Pa and 18 Pa. For a given specific energy level, the performance increased with a decrease in facility background pressure. Lowering the background pressure also caused a dramatic change in the voltage-current characteristic and the voltage stability, a phenomenon not previously reported with conventional supersonic-arc-attachment thrusters.

Sankovic, John M.↗
NASA NTRS2001

Linking Science Analysis with Observation Planning: A Full Circle Data Lifecycle

A clear goal of the Virtual Observatory (VO) is to enable new science through analysis of integrated astronomical archives. An additional and powerful possibility of the VO is to link and integrate these new analyses with planning of new observations. By providing tools that can be used for observation planning in the VO, the VO will allow the data lifecycle to come full circle: from theory to observations to data and back around to new theories and new observations. The Scientist's Expert Assistant (SEA) Simulation Facility (SSF) is working to combine the ability to access existing archives with the ability to model and visualize new observations. Integrating the two will allow astronomers to better use the integrated archives of the VO to plan and predict the success of potential new observations. The full circle lifecycle enabled by SEA can allow astronomers to make substantial leaps in the quality of data and science returns on new observations. Our paper will examine the exciting potential of integrating archival analysis with new observation planning, such as performing data calibration analysis on archival images and using that analysis to predict the success of new observations, or performing dynamic signal-to-noise analysis combining historical results with modeling of new instruments or targets. We will also describe how the development of the SSF is progressing and what has been its successes and challenges.

Jones, Jeremy↗
NASA NTRS2010

Testing to Characterize the Advanced Stirling Radioisotope Generator Engineering Unit

The Advanced Stirling Radioisotope Generator (ASRG), a high efficiency generator, is being considered for space missions. Lockheed Martin designed and fabricated an engineering unit (EU), the ASRG EU, under contract to the Department of Energy. This unit is currently undergoing extended operation testing at the NASA Glenn Research Center to generate performance data and validate life and reliability predictions for the generator and the Stirling convertors. It has also undergone performance tests to characterize generator operation while varying control parameters and system inputs. This paper summarizes and explains test results in the context of designing operating strategies for the generator during a space mission and notes expected differences between the EU performance and future generators.

Lewandowski, Edward↗
NASA NTRS2009

The Effect of Center of Gravity and Anthropometrics on Human Performance in Simulated Lunar and Mars Gravity

Drawing from the experiences of the Apollo missions, it is evident that the off nominal center of gravity (CG) induced by the portable life support system (PLSS) had significant impact on the locomotion stability of the crew. This in turn is believed to have been a major contributor to the high numbers of falls and high metabolic rates experienced by the crew, and thus significantly hampered the crew s performance. With this in mind, the EVA Physiology, Systems and Performance (EPSP) group at the NASA Johnson Space Center (JSC) has been conducting tests to assess how spacesuit CG location impacts human performance in simulated lunar and Mars gravity. The results acquired to date show correlations between CG location and performance. However, noticeable variations in the performance data have been observed across subjects for fixed CG configurations. Consequently, it was hypothesized that this variability may be attributed to the anthropometrics of the different test subjects. It was further hypothesized that trunk-to-height ratio (THR) may be directly correlated to performance in reduced gravity; i.e. subjects with increased THR may have increased performance. To test this hypothesis, lunar and Mars gravity test data acquired over three years during NASA Neural Buoyancy Lab (NBL) tests and NASA Extreme Environment Missions Operation (NEEMO) missions were analyzed against THR, height, trunk length, and subject body mass/weight. The results of the study supported the hypothesis relating THR and performance, while the other three anthropometric parameters did not provide consistent correlations with performance. This in turn suggests that human performance in reduced gravity may be more dependent on anthropometric proportions than on body segment lengths and mass/weight.

Mulugeta, Lealem↗
NASA NTRS1994

Statistical Analysis of NAS Parallel Benchmarks and LINPACK Results

In the last three years extensive performance data have been reported for parallel machines both based on the NAS Parallel Benchmarks, and on LINPACK. In this study we have used the reported benchmark results and performed a number of statistical experiments using factor, cluster, and regression analyses. In addition to the performance results of LINPACK and the eight NAS parallel benchmarks, we have also included peak performance of the machine, and the LINPACK n and n(sub 1/2) values. Some of the results and observations can be summarized as follows: 1) All benchmarks are strongly correlated with peak performance. 2) LINPACK and EP have each a unique signature. 3) The remaining NPB can grouped into three groups as follows: (CG and IS), (LU and SP), and (MG, FT, and BT). Hence three (or four with EP) benchmarks are sufficient to characterize the overall NPB performance. Our poster presentation will follow a standard poster format, and will present the data of our statistical analysis in detail.

Meuer, Hans-Werner↗
NASA NTRS2004

The Airline Quality Rating 2004

The Airline Quality Rating (AQR) was developed and first announced in early 1991 as an objective method of comparing airline quality on combined multiple performance criteria. This current report, the Airline Quality Rating 2004, reflects monthly Airline Quality Rating scores for 2003. AQR scores far the calendar year 2003 are based on 15 elemnts in four major areas that focus on airline performance aspects important to air travel consumers. The Airline Quality Rating 2004 is a summary of month-by-month quality ratings for U.S. airlines that have at least 1% of domestic passenger volume during 2003. Using the Airline Quality Rating system of weighted averages and monthly performance data in the areas of on-time arrivals, involuntary denied boardings, mishandled baggage, and a combination of 12 customer complaint categories, airlines comparative performance for the calendar year of 2003 is reported. This research monograph contains a brief summary of the AQR methodology, detailed data and charts that track comparative quality for domestic airline operations for the 12-month period of 2003, and industry results. Also, comparative Airline Quality Rating data for 2002 are included, where available, to provide historical perspective

Bowen, Brent D.↗
NASA NTRS1973

Stratoscope 2 integrating television camera

The development, construction, test and delivery of an integrating television camera for use as the primary data sensor on Flight 9 of Stratoscope 2 is described. The system block diagrams are presented along with the performance data, and definition of the interface of the telescope with the power, telemetry, and communication system.

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