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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 1,369 records · Page 76
All sourcesNASA NTRSDOE OSTI
NASA NTRS1981

Lessons from NASA

Particular requirements related to the design and the operation of spacecraft have forced NASA to take a reliability approach that differs somewhat from that used in many other applications. NASA has found that some of the traditional tools of reliability engineering, such as life testing, reliability demonstration testing, maintainability analysis, and direct failure analysis, are impractical for spacecraft. In place of a statistical approach, the space agency uses an engineering approach to mission reliability. Reliability is to be obtained with the aid of three different approaches, including the application of effective design principles, the control and screening of all parts, and the testing of the entire spacecraft or its prototype for predicted capabilities. Attention is given to failure-mode analysis, the enhancement of Voyager reliability by autonomous operation, the redundancy in Shuttle design, the weeding out of bad hardware, and the preference for off-the-shelf devices.

Williams, W. C.↗
NASA NTRS1982

PV history: Lessons for the future

A history of terrestrial photovoltaics is presented indicating that the photovoltaic potential was well perceived and a good technology developent plan was formulated and implemented. Major accomplishments of the technology plan are highlighted. Research objectives and research needs for the future are outlined.

Ralph, E. L.↗
NASA NTRS1982

Solar wind interaction with comets - Lessons from Venus

Data on the solar wind interaction with Venus are examined for the purpose of comparison with similar processes that may occur in comets. Attention is given to bow shock, magnetosheath, ionopause, ionosphere, and magnetotail of Venus. These features are compared with, respectively, the bow shock, magnetosheath, contact surface, coma, and plasma tail of a comet. It is concluded that observations of the solar wind interaction with Venus should provide new insight into the solar wind interaction with comets.

Russell, C. T.↗
NASA NTRS1983

Some lessons from NACA/NASA aerodynamic studies following World War II

An historical account is presented of the new departures in aerodynamic research conducted by NACA, and subsequently NASA, as a result of novel aircraft technologies and operational regimes encountered in the course of the Second World War. The invention and initial development of the turbojet engine furnished the basis for a new speed/altitude regime in which numerous aerodynamic design problems arose. These included compressibility effects near the speed of sound, with attendant lift/drag efficiency reductions and longitudinal stability enhancements that were accompanied by a directional stability reduction. Major research initiatives were mounted in the investigation of swept, delta, trapezoidal and variable sweep wing configurations, sometimes conducted through flight testing of the 'X-series' aircraft. Attention is also given to the development of the first generation of supersonic fighter aircraft.

Spearman, M. L.↗
NASA NTRS1983

Lessons learned from the CSIS

A discussion is presented of the Centralized Storm Information System (CSIS), a joint effort by several organizations including NASA and the National Weather Service, which has been developed to aid the forecaster in evaluating weather data. The CSIS was developed to provide a handling, analyzing, intercomparison, and display system for real-time data from all available sources. The CSIS hardware and software, the impact of the CSIS, and the initial experience gained following the implementation of the CSIS are examined. Several general insights learned from this interactive processing system are examined in detail, including the benefits of an evolutionary bottom up rather than top down design approach, the crucial nature of scheduler function to any real time system, the recognition that meteorological interactive terminals requirements are different from image processing terminals requirements, and the knowledge that forecasters generate a large peak load on computer resources.

Mosher, F. R.↗
NASA NTRS1983

Shuttle Performance: Lessons Learned, part 1

Beginning with the first orbital flight of the Space Shuttle, a great wealth of flight data became available to the aerospace community. These data were immediately subjected to analyses by several different groups with different viewpoints and motivations. The results were collected and presented in several papers in the subject areas of ascent and entry aerodynaics; guidance, navigation, and control; aerothermal environment prediction; thermal protection systems; and measurement techniques.

James P Arrington↗
NASA NTRS1983

Space Shuttle Orbiter Venting: Lessons Learned

The orbiter vent system provides dedicated vent areas to permit the gases trapped inside the vehicle to escape during accent. The same vent system also repressurizes the vehicle during entry. The vent system is one of six systems that constitutes the purge, vent and drain subsystem. The orbiter active vent system has been very adaptable to the changing requirements that have occurred during the development of the Space Shuttle orbiter. Good correlation has been obtained between predicted and measured compartment pressures during the orbital flight test (OFT) program. An investigation of the flight data showed that the difference between preflight prediction and the measured values were primarily due to the difference between the baseline external pressures, which was based on subscale wind tunnel test data, and the actual vehicle local external pressures measured during the flight. The current predictions are based on flight derived vent port pressure coefficients since the wind tunnel data does not adequately define the orbiter ascent pressure environment.

H S Lutfi↗
NASA NTRS1983

Explanation of the hypersonic longitudinal stability problem: Lessons learned

Inviscid and viscous CFD codes have been applied to a modified Space Shuttle orbiter geometry to investigate differences between preflight aerodynamic predictions and aerodynamic data from hypersonic reentry flight. Flow field solutions were obtained for wind tunnel conditions and flight conditions to assess Mach number, real-gas, and viscous effects on the reentry aerodynamics of the orbiter. Based on the CFD studies, a methodology model has been developed to (1) extrapolate wind tunnel data to flight conditions and (2) calculate a DCM for use with the Aerodynamic Design Data Book. Comparisons are made with selected flight data. Results of the study indicate that the differences between flight and pre-STS-1 predictions of hypersonic pitching moment are primarily due the to Mach number and real-gas effects.

Griffith, B. J.↗
NASA NTRS1983

Aerodynamic coefficient identification package dynamic data accuracy determinations: Lessons learned

The errors in the dynamic data output from the Aerodynamic Coefficient Identification Packages (ACIP) flown on Shuttle flights 1, 3, 4, and 5 were determined using the output from the Inertial Measurement Units (IMU). A weighted least-squares batch algorithm was empolyed. Using an averaging technique, signal detection was enhanced; this allowed improved calibration solutions. Global errors as large as 0.04 deg/sec for the ACIP gyros, 30 mg for linear accelerometers, and 0.5 deg/sec squared in the angular accelerometer channels were detected and removed with a combination is bias, scale factor, misalignment, and g-sensitive calibration constants. No attempt was made to minimize local ACIP dynamic data deviations representing sensed high-frequency vibration or instrument noise. Resulting 1sigma calibrated ACIP global accuracies were within 0.003 eg/sec, 1.0 mg, and 0.05 deg/sec squared for the gyros, linear accelerometers, and angular accelerometers, respectively.

Heck, M. L.↗
NASA NTRS1983

Shuttle Performance: Lessons Learned, Part 2

Several areas of Space Shuttle technology were addressed including aerothermal environment, thermal protection, measurement and analysis, Shuttle carrier aerodynamics, entry analysis of the STS-3, and an overview of each section.

Arrington, J. P.↗
NASA NTRS1983

Orbiter Entry Heating Lessons Learned from Development Flight Test Program

The Space Shuttle orbiter's thermal protection system (TPS), designed mainly on the basis of wind tunnel test data, has successfully completed its design, development, and flight test program. The flight test data provide an exceptional opportunity to evaluate the use of wind tunnel test data for the design of TPS for reentry vehicles. Comparisons of flight test data against wind tunnel data used to design the orbiter's TPS were developed. These flight data, though still in the preliminary analysis phases, generally support the use of wind tunnel test data in the design of TPS for hypersonic reentry vehicles.

Haney, J. W., Jr.↗
NASA NTRS1983

Shuttle flight pressure instrumentation: Experience and lessons for the future

Flight data obtained from the Space Transportation System orbiter entries are processed and analyzed to assess the accuracy and performance of the Development Flight Instrumentation (DFI) pressure measurement system. Selected pressure measurements are compared with available wind tunnel and computational data and are further used to perform air data analyses using the Shuttle Entry Air Data System (SEADS) computation technique. The results are compared to air data from other sources. These comparisons isolate and demonstrate the effects of the various limitations of the DFI pressure measurement system. The effects of these limitations on orbiter performance analyses are addressed, and instrumentation modifications are recommended to improve the accuracy of similar fight data systems in the future.

Siemers, P. M., III↗
NASA NTRS1983

AFTI/F-16 flight test results and lessons

The advanced fighter technology integration (AFTI) F-16 aircraft is a highly complex digital flight control system integrated with advanced avionics and cockpit. The use of dissimilar backup modes if the primary system fails requires the designer to trade off system simplicity and capability. The tradeoff is evident in the AFTI/F-16 aircraft with its limited stability and fly by wire digital flight control systems when a generic software failure occurs the backup or normal mode must provide equivalent envelop protection during the transition to degraded flight control. The complexity of systems like the AFTI/F-16 system defines a second design issue, which is divided into two segments: (1) the effect on testing, (2) and the pilot's ability to act correctly in the limited time available for cockpit decisions. The large matrix of states possible with the AFTI/F-16 flight control system illustrates the difficulty of both testing the system and choosing real time pilot actions. The third generic issue is the possible reductions in the user's reliability expectations where false single channel information can be displayed at the pilot vehicle interface while the redundant set remains functional.

Ishmael, S. D.↗
NASA NTRS1983

AFTI/F-16 flight test results and lessons

The AFTI/F-16 flight test program is summarized, and several design issues of general interest are addressed. A brief description is given of the test vehicle, its flight control modes, and the flight envelopes in which testing was performed. Flight test results are summarized by addressing benefits experienced in flight control task-tailoring, handling qualities in mission tasks, aircraft structure considerations, digital flight control system performance, and human factors. Finally, several design issues relevant to future fighter aircraft are examined, including degraded flight control, system complexity, simplex information in redundant systems, and single failure propagation in redundant systems.

Ishmael, S. D.↗
NASA NTRS1984

Lessons learned during the first year of the TDRSS

The Tracking and Data Relay Satellite System (TDRSS) is the National Aeronautics and Space Administration's (NASA) newest capability for tracking and communicating with NASA's low-earth orbiting scientific and operational satellites. This support will eventually be provided through three identical satellites in geosynchronous orbit. They will relay data through a single ground station located in New Mexico. This paper discusses both the overall TDRSS concept and NASA's experience to date with the first of the three relay satellites on station.

Aller, R. O.↗
NASA NTRS1985

Crystalline-silicon reliability lessons for thin-film modules

The reliability of crystalline silicon modules has been brought to a high level with lifetimes approaching 20 years, and excellent industry credibility and user satisfaction. The transition from crystalline modules to thin film modules is comparable to the transition from discrete transistors to integrated circuits. New cell materials and monolithic structures will require new device processing techniques, but the package function and design will evolve to a lesser extent. Although there will be new encapsulants optimized to take advantage of the mechanical flexibility and low temperature processing features of thin films, the reliability and life degradation stresses and mechanisms will remain mostly unchanged. Key reliability technologies in common between crystalline and thin film modules include hot spot heating, galvanic and electrochemical corrosion, hail impact stresses, glass breakage, mechanical fatigue, photothermal degradation of encapsulants, operating temperature, moisture sorption, circuit design strategies, product safety issues, and the process required to achieve a reliable product from a laboratory prototype.

Ross, R. G., Jr.↗