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At least 1,063 records · Page 59

Astronautics and Aeronautics, 1966

At the opening of the tenth year in the era of man’s mobility in outer space, we can look back on 1966 as offering convincing evidence that the United States had gained great competence. This evidence included: five orbital space flights by ten Gemini astronauts; four lunar missions undertaking the orbiting of and soft landing on the moon; numerous contributions to scientific knowledge by unmanned spacecraft and sounding rockets; and further demonstrations of the practical utility of operational space systems, including weather and communications satellites. During 1966, a record 100 American spacecraft were placed into earth orbit or on escape trajectories. Thousands of revealing and useful pictures of the earth were taken from space and of the moon from lunar orbit and on its surface. The Gemini program ended with rendezvous and docking experiments and extravehicular activity by the Gemini test pilots as the Apollo R&D test flights leading to the manned lunar mission came into the schedule. Thirty-five major scientific, technological, and operational milestones were cited for 1966 by the President in his Report to the Congress on aeronautical and space activities of the United States. This was one measure of the American commitment to share in the peaceful exploration of space for all mankind. Another was our support of the final steps toward a United Nations space treaty, undertaken to ensure that the peaceful exploitation of space had juridical basis in international law. Spectacular as some events in the space venture were in 1966, they nonetheless came to have diminished novelty in the eyes of many laymen. The multitude of both important and unspectacular space activities attained almost an accepted and routine place. This volume, as well as its predecessor chronicles, offers a ready reference on the major as well as the less-well known events. Beyond the welter of documented details on the complex nature of aeronautical and space related events and their impact, this volume helps to provide a better perspective upon today as we contemplate tomorrow. Such intent also serves future historians and analysts who cannot be unmindful of what is herein presented. When the Congress created the National Aeronautics and Space Administration in 1958, it charged NASA with the responsibility to “contribute materially to . . . the expansion of human knowledge of phenomena in the atmosphere and space’’ and to “provide for the widest practical and appropriate dissemination of information concerning its activities and results thereof.” NASA has attempted to do this and to include documentation for the historical record. The relating of NASA history begins with this day-by day chronicle and leads to more specialized studies and histories of the unprecedented task of extending man’s mobility and understanding beyond his planet. While a chronology cannot in itself serve as a full-fledged history, the size of this annual volume alone is illustrative of the scope and complexity of the historical task yet to be completed as memories fade and the records disappear.

SPACE PROBE↗

Research in the Restricted Problems of Three and Four Bodies Final Scientific Report

Seven studies have been conducted on research in the existence and nature of solutions of the restricted problems of three and four bodies. The details and results of five of these research investigations have already been published, and the latest two studies will be published shortly. A complete bibliography of publications is included in this report. This research has been primarily qualitative and has yielded new information on the behavior of trajectories near the libration points in the Earth-Moon-Sun and Sun-Jupiter-Saturn systems, and on the existence of periodic trajectories about the libration points of the circular and elliptical restricted four-body models. We have also implemented Birkhoff's normalization process for conservative and nonconservative Hamiltonian systems with equilibrium points. This makes available a technique for analyzing stability properties of certain nonlinear dynamical systems, and we have applied this technique to the circular and elliptical restricted three-body models. A related study was also conducted to determine the feasibility of using cislunar periodic trajectories for various space missions. Preliminary results suggest that this concept is attractive for space flight safety operations in cislunar space. Results of this research will be of interest to mathematicians, particularly those working in ordinary differential equations, dynamical systems and celestial mechanics; to astronomers; and to space guidance and mission analysts.

Richards, Paul B.↗

Space Flight Handbooks. Volume 3, Planetary Flight Handbook: Mars Stopover Missions Using Venus Swingbys - Part 6

This volume of the NASA Planetary Flight Handbook contains trajectory data to aid the mission analyst in the planning of stopover missions to Mars that employ the Venus swingby mode. Compared to other mission modes, the Venus swingbys yield substantial reductions in propulsive velocity and Earth entry speed requirements when employed as part of a round trip stopover mission. Conversely, the swingbys are at best, of marginal utility for one-way missions. Consequently, this Handbook has been tailored expressly for use in the planning of round trip missions. The relevant charts, graphs, and tabular data are presented for the totality of such missions, i.e., in terms of total round trip mission duration and stopover time at Mars. Recognizing, however, that within the context of round trip missions the single-leg data can be of importance in certain phases of the mission analyses, all such data has been preserved on a master magnetic tape. Copies of this tape will be made available to interested organizations.

Source record↗

Methodologies for optimal resource allocation to the national space program and new space utilizations. Volume 2: Resource allocation and smoothing model, programmer's manual

Appendixes are presented that provide model input requirements, a sample case, flow charts, and a program listing. At the beginning of each appendix, descriptive details and technical comments are provided to indicate any special instructions applicable to the use of that appendix. In addition, the program listing includes comment cards that state the purpose of each subroutine in the complete program and describe operations performed within that subroutine. The input requirements includes details on the many options that adapt the program to the specific needs of the analyst for a particular problem.

Source record↗

Nuclear reactor descriptions for space power systems analysis

For the small, high performance reactors required for space electric applications, adequate neutronic analysis is of crucial importance, but in terms of computational time consumed, nuclear calculations probably yield the least amount of detail for mission analysis study. It has been found possible, after generation of only a few designs of a reactor family in elaborate thermomechanical and nuclear detail to use simple curve fitting techniques to assure desired neutronic performance while still performing the thermomechanical analysis in explicit detail. The resulting speed-up in computation time permits a broad detailed examination of constraints by the mission analyst.

Mccauley, E. W.↗

A modular approach for assessing the effect of radiation environments on man in operational systems. The radiobiological vulnerability of man during task performance

A modular approach for assessing the affects of radiation environments on man in operational systems has been developed. The feasibility of the model has been proved and the practicality has been assessed. It has been applied to one operational system to date and information obtained has been submitted to systems analysts and mission planners for the assessment of man's vulnerability and impact on systems survivability. In addition, the model has been developed so that the radiobiological data can be input to a sophisticated man-machine interface model to properly relate the radiobiological stress with other mission stresses including the effects of a degraded system.

Ewing, D. E.↗

Longitudinal stability and control derivatives of a jet fighter airplane extracted from flight test data by utilizing maximum likelihood estimation

A method of parameter extraction for stability and control derivatives of aircraft from flight test data, implementing maximum likelihood estimation, was developed and successfully applied to actual longitudinal flight test data from a modern sophisticated jet fighter. The results of this application establish the merits of the estimation technique and its computer implementation(allowing full analyst interaction with the program) as well as provide data for the validation of a portion of the differential maneuvering simulator (DMS). The results are presented for all flight test runs in tabular form and as time history comparisons between the estimated states and the actual flight test data. Comparisons between extracted and manufacturer's values for five major derivatives are presented and reveal good agreement for these principal derivatives with one exception. This particular derivative is extensively investigated by utilizing the interactive capabilities of the computer program. The results of this investigation verify the numbers extracted by maximum likelihood estimation.

Steinmetz, G. G.↗

Preliminary design of an auxiliary power unit for the space shuttle. Volume 5: Selected system cycle performance data

Detailed cycle steady-state performance data are presented for the final auxiliary power unit (APU) system configuration. The selection configuration is a hydrogen-oxygen APU incorporating a recuperator to utilize the exhaust energy and using the cycle hydrogen flow as a means of cooling the component heat loads. The data are given in the form of computer printouts and provide the following: (1) verification of the adequacy of the design to meet the problem statement for steady-state performance; (2) overall system performance data for the vehicle system analyst to determine propellant consumption and hydraulic fluid temperature as a function for varying mission profiles, propellant inlet conditions, etc.; and (3) detailed component performance and cycle state point data to show what is happening in the cycle as a function of the external forcing functions.

Hamilton, M. L.↗

Translation of shuttle operations simulation from GPSS 2 to GPSS 1100

A method has been developed which enables a programmer to convert the General Purpose Systems Simulator (GPSS) 2 simulation language into the GPSS 1100 language. To accomplish the conversion, a translator deck is used in addition to hand changes made by the analyst after translation. The conversion of a particular GPSS 2 program used at the Marshall Space Flight Center (MSFC) is reported and major changes required for compatibility of the two languages are summerized. Validation of the GPSS 1100 model was completed by comparing the results of the GPSS 2 statistics to the converted 1100 model.

Marshall, A. J.↗

Fatigue design procedure for the American SST prototype

For supersonic airline operations, significantly higher environmental temperature is the primary new factor affecting structural service life. Methods for incorporating the influence of temperature in detailed fatigue analyses are shown along with current test indications. Thermal effects investigated include real-time compared with short-time testing, long-time temperature exposure, and stress-temperature cycle phasing. A method is presented which allows designers and stress analyzers to check fatigue resistance of structural design details. A communicative rating system is presented which defines the relative fatigue quality of the detail so that the analyst can define cyclic-load capability of the design detail by entering constant-life charts for varying detail quality. If necessary then, this system allows the designer to determine ways to improve the fatigue quality for better life or to determine the operating stresses which will provide the required service life.

Doty, R. J.↗

Lateral stability and control derivatives of a jet fighter airplane extracted from flight test data by utilizing maximum likelihood estimation

A method of parameter extraction for stability and control derivatives of aircraft from flight test data, implementing maximum likelihood estimation, has been developed and successfully applied to actual lateral flight test data from a modern sophisticated jet fighter. This application demonstrates the important role played by the analyst in combining engineering judgment and estimator statistics to yield meaningful results. During the analysis, the problems of uniqueness of the extracted set of parameters and of longitudinal coupling effects were encountered and resolved. The results for all flight runs are presented in tabular form and as time history comparisons between the estimated states and the actual flight test data.

Parrish, R. V.↗

Some aspects of the NASTRAN program output

The NASTRAN program output is discussed from a structural analysts point of view, and the simple modifications which were made to the program in order to improve it are also described. The convenience of the output for use in original design work is critically appraised and compared with the output from ASTRAL. It is shown that considerable hand calculation is necessary in order to extract useful load distribution data from the available NASTRAN output. For this reason, some effort was directed toward providing additional force output for the NASTRAN shear panel element.

Gregory, D. J.↗

NASTRAN data generation and management using interactive graphics

A method of using an interactive graphics device to generate a large portion of the input bulk data with visual checks of the structure and the card images is described. The generation starts from GRID and PBAR cards. The visual checks result from a three-dimensional display of the model in any rotated position. By detailing the steps, the time saving and cost effectiveness of this method may be judged, and its potential as a useful tool for the structural analyst may be established.

Smootkatow, M.↗

Synthesis of stiffness and mass matrices from experimental vibration modes.

With highly complex structures, it is sometimes desirable to derive a dynamic model of the system from experimental vibration data. This paper presents algorithms for synthesizing the mass and stiffness matrices from experimentally derived modal data in a way which preserves the physical significance of the individual mass and stiffness elements. The synthesizing procedures allow for the incorporation of other mass and stiffness data, whether empirical or based on the analyst's insight. The mass and stiffness matrices are derived for a cantilever beam example and are compared with those obtained using earlier techniques.

Ross, R. G., Jr.↗

Static and dynamic load measurements in aerospace decelerator canopy fabrics with metal foil strain gages.

A test program was conducted to determine the feasibility of using conventional metal foil strain gages to measure load-time relationships on thin fabric membranes while these membranes were loaded under simulated aerodynamic decelerator conditions. Uniaxial and biaxial tests were made at fabric strain levels up to about 10%. Loadings were made both statically and dynamically, with the fastest load time being 0.015 second for zero to full load on uniaxial test specimens. For the biaxial tests, plane strain conditions were assumed, and by using experimentally determined strain-load relationships, principal loads were determined from the perpendicularly oriented strain-gage pairs. Although the complex stress-strain behavior of decelerator fabrics prevents the attainment of normally expected strain-gage accuracy, utilization of the techniques described can lead to meaningful measurements for the decelerator stress analyst.

Hoffman, I. S.↗

Estimating trajectory correction requirements for the Outer Planets Grand Tour missions.

The estimation of trajectory correction requirements for the Outer Planets Grand Tour (OPGT) missions poses a unique and many-faceted problem for the systems analyst. In this paper the navigation concept for the OPGT is developed and illustrated. The limiting accuracies and performance of the combined radio/onboard optical system are examined. The combined orbit determination system is characterized by its accuracy and by its system risks. Such considerations are included with the statistical combination of maneuver estimates to produce preliminary delta V estimates for the planned OPGT missions.

Friedman, L. D.↗

Basic parameters for low thrust mission and system analysis.

Development of a basic set of normalized parameters to represent low-thrust system characteristics. The conditions which must be met to obtain trajectory and performance data which are invariant with the launch vehicle characteristics, the selected power, the specific mass of the low-thrust vehicle, and the efficiency of the ion propulsion system are derived. This normalized representation of mission characteristics frees the analyst from having to rerun the trajectories if any of the aforementioned parameters are varied. Examples pertaining to a low-thrust Jupiter flyby and comet Encke rendezvous are given to demonstrate the utility of the method of presentation.

Barber, T. A.↗