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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 667 records · Page 37
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NASA NTRS1982

Wind estimation using air data probe measurements to evaluate meteorological measurements made during Space Shuttle entries

Deterministic and weighted least squares methods for obtaining estimates of the horizontal winds encountered during the Shuttle entry phase are described. The estimates are based on in situ Air Data System (ADS) measurements of angle-of-attack, side-slip angle and true airspeed, in conjunction with inertial trajectory parameters obtained from the post flight trajectory reconstruction. Accuracies in the wind estimates obtained from each method are assessed using both theoretical arguments and flight results. Comparisons of derived winds with meteorological measurements taken during the first three Shuttle entries have demonstrated: (1) the usefulness of the wind estimators for evaluating meteorological measurements below 50 kft, and (2) the potential for adequate wind determinations in the absence of independent wind measurements. Comparisons of STS-3 flight-derived L/D versus predicted values from the LaRC aerodynamic data base are presented from 50 kft to touchdown. These results exemplify the importance of such determinations to enhance the ongoing Shuttle aerodynamic and aerothermodynamic research.

Kelly, G. M.↗
NASA NTRS1982

Shuttle entry GN&C performance during STS-1 and STS-2

Data obtained during the entry segment of the descent phase of the flights are analyzed. The nominal entry profile is defined and a description is given of the guidance, navigation, and control subsystem. Emphasis is placed on the stability and control problems encountered during STS-1 and to the changes made in response to these anomalies. These are: (1) the first roll maneuver was done manually at a reduced roll rate; (2) the nominal elevator position was changed from one degree up to one degree down for Mach numbers greater than 12 to reduce the heat load on the body flap; (3) the pilot was directed to execute small roll maneuvers at dynamic pressures of 4, 8, and 18 psf to help determine the roll moment from the aft yaw jets; (4) the planned test inputs in the transonic region were reduced in magnitude; and (5) the targeted touchdown point was moved 500 feet closer to the runway threshold.

Mcwhorter, L. B.↗
NASA NTRS1983

Space Shuttle third flight /STS-3/ entry RCS analysis

Flight data obtained from three Space Transportation System orbiter entries (STS-1, 2, and 3) are processed and analyzed to determine the roll interactions caused by the firing of the entry reaction control system (RCS). Comparisons between the flight-derived parameters and the predicted derivatives without interaction effects are made. The flight-derived RCS Plume flow-field interaction effects are independently deduced by direct integration of the incremental changes in the wing upper surface pressures induced by RCS side thruster firings. The separately obtained interaction effects are compared to the predicted values and the differences are discussed.

Scallion, W. I.↗
NASA NTRS1983

Galileo atmospheric entry probe mission description

The mission goals, control parameters, and instrumentation for the Galileo entry probe are described. The goal for the probe is to penetrate the Jovian atmosphere to 10 bars, begin data gathering and transmission at about 0.1 bar, and make as many in-situ cloud measurements as possible. The probe will pass through a 16,000 K shock layer, which has led to a ratio of 5 kg of heat shield to every kg of instrumentation on the probe. An entry angle between -7.0 to -10.2 deg will be used, and possible targets with respect to declinations associated with a 1986 launch are discussed. The preentry mission phase, entry/descent sequence, and the baseline mission relay link performance are outlined. Data may be available down to 20 bars, and the probe performance will aid in design goals for subsequent Saturn and Uranus probes.

Vojvodich, N. S.↗
NASA NTRS1983

Shuttle Entry Air Data System concepts applied to Space Shuttle Orbiter flight pressure data to determine air data - STS 1-4

The Shuttle Entry Air Data System (SEADS) is the implementation of a new concept in air data systems, with application to entry vehicles. This concept incorporates an array of flush orifices in the nose and forward fuselage of the vehicle and a new flowfield modeling concept for the analysis of flight data and the determination of the required air data parameters. Although the SEADS has not been fully demonstrated, a developmental analysis capability has been assembled and demonstrated. This analytical capability has been used to analyze selected Development Flight Instrumentation (DFI) pressure data from STS-1 through STS-4 and determine angle of attack and freestream dynamic pressure. The results of this study verify the potential of the SEADS as a highly fault tolerant operational air data system. In addition, the transition of SEADS from its present status as an experimental system to an operational system is shown to be readily achievable.

Siemers, P. M., III↗
NASA NTRS1983

A comparison of measured and theoretical predictions for STS ascent and entry sonic booms

Sonic boom measurements have been obtained during the flights of STS-1 through 5. During STS-1, 2, and 4, entry sonic boom measurements were obtained and ascent measurements were made on STS-5. The objectives of this measurement program were (1) to define the sonic boom characteristics of the Space Transportation System (STS), (2) provide a realistic assessment of the validity of xisting theoretical prediction techniques, and (3) establish a level of confidence for predicting future STS configuration sonic boom environments. Detail evaluation and reporting of the results of this program are in progress. This paper will address only the significant results, mainly those data obtained during the entry of STS-1 at Edwards Air Force Base (EAFB), and the ascent of STS-5 from Kennedy Space Center (KSC). The theoretical prediction technique employed in this analysis is the so called Thomas Program. This prediction technique is a semi-empirical method that required definition of the near field signatures, detailed trajectory characteristics, and the prevailing meteorological characteristics as an input. This analytical procedure then extrapolates the near field signatures from the flight altitude to an altitude consistent with each measurement location.

Garcia, F., Jr.↗
NASA NTRS1983

Local Calcium Entry and the Guidance of Growth

The role of calcium in developing cells is illustrated. The Fucus egg, a brown algae is used to describe this phenomenom. Results of local calcium entry and forced calcium entry into the eggs are given.

Robinson, K. R.↗
NASA NTRS1984

Effect of aerodynamic and angle-of-attack uncertainties on the blended entry flight control system of the Space Shuttle from Mach 10 to 2.5

A six-degree-of-freedom simulation analysis has been performed for the Space Shuttle Orbiter during entry from Mach 10 to 2.5 with realistic off-nominal conditions using the entry flight control system specified in May 1978. The off-nominal conditions included the following: (1) aerodynamic uncertainties, (2) an error in deriving the angle of attack from onboard instrumentation, (3) the failure of two of the four reaction control-system thrusters on each side, and (4) a lateral center-of-gravity offset. With combinations of the above off-nominal conditions, the control system performed satisfactorily with a few exceptions. The cases that did not exhibit satisfactory performance displayed the following main weaknesses. Marginal performance was exhibited at hypersonic speeds with a sensed angle-of-attack error of 4 deg. At supersonic speeds the system tended to be oscillatory, and the system diverged for several cases because of the inability to hold lateral trim. Several system modifications were suggested to help solve these problems and to maximize safety on the first flight: alter the elevon-trim and speed-brake schedules, delay switching to rudder trim until the rudder effectiveness is adequate, and reduce the overall rudder loop gain. These and other modifications were incorporated in a flight-control-system redesign in May 1979.

Stone, H. W.↗
NASA NTRS1984

Real-gas simulation for the Shuttle Orbiter and planetary entry configurations including flight results

By testing configurations in a gas (like CF4) which can produce high normal-shock density ratios, such as those encountered during hypersonic entry, certain aspects of real-gas effects can be simulated. Results from force-moment, shock-shape and oil flow visualization tests are presented for both the Shuttle Orbiter and a 45 deg sphere-cone in CF4 and air at M = 6, and comparisons are made with flight results. Pitching-moment coefficients measured on a Shuttle Orbiter model in CF4 showed a nose-up increment, compared with air results, that was almost identical to the difference between preflight predictions and flight in the high hypersonic regime. The drag coefficient measured in CF4 on the 45 deg sphere-cone, which is the same configuration used on the forebody of the Pioneer Venus entry vehicles, showed excellent agreement with flight data at M = 6.

Calloway, R. L.↗
NASA NTRS1985

A color graphics presentation of the Space Shuttle Orbiter windward surface entry temperature distribution

The windward surface temperature response measured during the fifth entry of the Space Shuttle Columbia is presented as solid filled color contour plots. These plots show the data from 92 instruments, at selected points in time, in a manner which makes the temperature extremes and gradients immediately obvious. Several physical phenomena, such as separated flow caused by the deflected body flap, local heating at the elevon-elevon gap, an overview of the propagation of boundary-layer transition over the Orbiter windward surface, and the thermal response of eight catalytically coated tiles, can be observed or inferred from the displayed temperatures. In addition, the maximums from each instrument have been contoured and are presented with a companion plot showing the percentage of surface area covered by each contour level. Also, the flight data are presented using the colors which correspond to the surface emittance as a function of temperature. To show the temperature transients, a computer-generated movie has been produced showing the temperature contours from 100 s to 1500 s after entry interface.

Martin, F. W., Jr.↗
NASA NTRS1985

Definition of an entry research vehicle

Within the last year, there has been a growing interest in technology which would support the development of vehicles which can maneuver in the atmosphere while returning from orbit and vehicles which can fly in the atmosphere at hypersonic speeds for sustained periods of time. This rebirth of interest in hypersonics is partly a result of a developing awareness of the potential benefits which can be derived from vehicles with capability to operate between the limits of existing aircraft and spacecraft. Examples of the types of maneuvers which are projected for this new class of vehicles are presented. Challenges provided by the considered maneuvers are summarized, taking into account a synergetic or atmospheric plane change. The plane change maneuver will require a Thermal Protection System (TPS). Attention is given to the definition of a Shuttle launched entry research vehicle experiment. Details regarding the synergetic plane change are considered along with the maneuvering entry, vehicle heating, and experiments and instrumentation.

Freeman, D. C.↗
NASA NTRS1986

Uniform engine testing program phase 7: NASA Lewis Research Center second entry

The propulsion and Energetics Panel, Working Group 15, of the Advisory Group for Aerospace Research and Development (AGARD) is sponsoring a Uniform Engine Testing Program (UETP). In this program, two jet engines were tested under identical conditions in certain NATO altitude and ground-level facilities as a means of correlating these facilities. With this second entry, NASA documented engine deterioration that may have occurred since inception of the UETP. Additionally, NASA investigated anomalies discovered during review of data from the five facilities which had participated in the program between the two NASA entries.

Biesiadny, T. J.↗
NASA NTRS1986

Engineering graphics data entry for space station data base

The entry of graphical engineering data into the Space Station Data Base was examined. Discussed were: representation of graphics objects; representation of connectivity data; graphics capture hardware; graphics display hardware; site-wide distribution of graphics, and consolidation of tools and hardware. A fundamental assumption was that existing equipment such as IBM based graphics capture software and VAX networked facilities would be exploited. Defensible conclusions reached after study and simulations of use of these systems at the engineering level are: (1) existing IBM based graphics capture software is an adequate and economical means of entry of schematic and block diagram data for present and anticipated electronic systems for Space Station; (2) connectivity data from the aforementioned system may be incorporated into the envisioned Space Station Data Base with modest effort; (3) graphics and connectivity data captured on the IBM based system may be exported to the VAX network in a simple and direct fashion; (4) graphics data may be displayed site-wide on VT-125 terminals and lookalikes; (5) graphics hard-copy may be produced site-wide on various dot-matrix printers; and (6) the system may provide integrated engineering services at both the engineering and engineering management level.

Lacovara, R. C.↗
NASA NTRS1987

Utilization of Global Reference Atmosphere Model (GRAM) for shuttle entry

At high latitudes, dispersions in values of density for the middle atmosphere from the Global Reference Atmosphere Model (GRAM) are observed to be large, particularly in the winter. Trajectories have been run from 28.5 deg to 98 deg. The critical part of the atmosphere for reentry is 250,000 to 270,000 ft. 250,000 ft is the altitude where the shuttle trajectory levels out. For ascending passes the critical region occurs near the equator. For descending entries the critical region is in northern latitudes. The computed trajectory is input to the GRAM, which computes means and deviations of atmospheric parameters at each point along the trajectory. There is little latitude dispersion for the ascending passes; the strongest source of deviations is seasonal; however, very wide seasonal and latitudinal deviations are exhibited for the descending passes at all orbital inclinations. For shuttle operations the problem is control to maintain the correct entry corridor and avoid either aerodynamic skipping or excessive heat loads.

Joosten, Kent↗
NASA NTRS1987

An Adaptive Numeric Predictor-corrector Guidance Algorithm for Atmospheric Entry Vehicles

An adaptive numeric predictor-corrector guidance is developed for atmospheric entry vehicles which utilize lift to achieve maximum footprint capability. Applicability of the guidance design to vehicles with a wide range of performance capabilities is desired so as to reduce the need for algorithm redesign with each new vehicle. Adaptability is desired to minimize mission-specific analysis and planning. The guidance algorithm motivation and design are presented. Performance is assessed for application of the algorithm to the NASA Entry Research Vehicle (ERV). The dispersions the guidance must be designed to handle are presented. The achievable operational footprint for expected worst-case dispersions is presented. The algorithm performs excellently for the expected dispersions and captures most of the achievable footprint.

Spratlin, Kenneth Milton↗
NASA NTRS1988

The proposal entry processor: Telescience applications for Hubble Space Telescope science operations

The Proposal Entry Processor (PEP) System supports the submission, entry, technical evaluation review, selection and implementation of Hubble Space Telescope (HST) observing proposals. The PEP system is described concentrating on features which illustrate principles of telescience as applied to the HST. These principles are applicable to other observatories, both space and ground based. The PEP proposal forms allow a scientist to specify scientific objectives without becoming needlessly involved in implementation details. The Remote Proposal Submission System (RPSS) allows proposers to submit proposals electronically via Telenet, SPAN, and other networks. The RPSS performs syntax and sematic checks on proposals. The PEP uses a fourth generation database system to store proposal information and to allow general queries and reports. The Transformation subsystem uses an expert system written in OPS5 to cast a scientific description of an observing program into parameters used by the planning and scheduling system. The TACOS system is a natural language database which supports the proposal selection process. Technical evaluations for resource usage and duplicate science are performed using rulebased systems.

Jackson, Robert↗
NASA NTRS1988

A model for multiple throat structures in the polar cap flow entry region

A two-dimensional ionospheric convection model has been developed to produce convection patterns for southward interplanetary magnetic field (IMF) and a positive or negative IMF y component. The model consists of a movable, shear convection reversal boundary with a gap in it where flux enters the polar cap. The sign of IMF B(y) determines the dayside gap geometry. This simple model is used to simulate measured ionospheric flows from the DE 2 satellite. Roughly 35 percent of DE 2 passes that cross the dayside between 0800 and 1400 hours MLT cannot be modeled with a single narrow flow entry region. By comparing model calculations and the measured ion flows, it is shown that the dayside flow entry region to the polar cap typically spans several hours in local time. The electric field can concentrate along portions of the polar cap entrance and weaken between the concentrated regions, thus forming multiple 'throats'.

Moses, J. J.↗
NASA NTRS1989

Avionics architecture studies for the entry research vehicle

This report is the culmination of a year-long investigation of the avionics architecture for NASA's Entry Research Vehicle (ERV). The Entry Research Vehicle is conceived to be an unmanned, autonomous spacecraft to be deployed from the Shuttle. It will perform various aerodynamic and propulsive maneuvers in orbit and land at Edwards AFB after a 5 to 10 hour mission. The design and analysis of the vehicle's avionics architecture are detailed here. The architecture consists of a central triply redundant ultra-reliable fault tolerant processor attached to three replicated and distributed MIL-STD-1553 buses for input and output. The reliability analysis is detailed here. The architecture was found to be sufficiently reliable for the ERV mission plan.

Dzwonczyk, M. J.↗