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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 145 records · Page 8

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NASA NTRS1977

Viking extended mission support

The period 1 March 1977 through 30 April 1977 is reported and includes Deep Space Network (DSN) Mark III data system testing. Status of the Viking DSN discrepancy reporting system as well as the status of Viking related tracking and command support were also considered. Operations support of Viking events and radio science activities were examined. Current progress on the major reconfiguration of the Network is presented in the context of support for the Viking extended mission.

Howe, T. W.↗

NASA NTRS1977

Viking mission support

Statistics listing the Deep Space Network tracking and command support and the discrepancy report status for 1 January through 28 February 1977 are presented in tables. The initial Viking extended mission period of normal DSN support, following the nonstandard operations during the solar conjunction period is included. Operational testing subsequent to the MK III data system installations at DSS 12, 44, and 62 during this period are also discussed.

Johnston, D. W. H.↗

NASA NTRS1977

Viking extended mission support

The period from 1 July through 31 August 1977 is covered and included is the remainder of post DSN Mark 3 Data Subsystem Implementation Project Viking-related testing at DSS14. Also included are reports on the Viking DSN Discrepancy Reporting System, Viking command support, tracking support, and periodic tests conducted with the Viking spacecraft.

Howe, T. W.↗

NASA NTRS1978

Viking extended mission support

The status of the Viking Deep Space Network Mark 3 '77 data subsystem implementation project and related testing at DSS 42/43 from 1 September through 31 October 1977 are reported. The Viking DSN discrepancy reporting system, Viking command support, tracking support, and periodic tests conducted with the Viking spacecraft are also discussed.

Howe, T. W.↗

NASA NTRS1978

Viking extended mission support

The Deep Space Network (DSN) support of Viking spacecraft activities and the DSN Viking command and tracking support are reported. The status of DSN Mark 3 data (MDS) subsystem implementation project related Viking testing is included.

Gillette, R. L.↗

NASA NTRS1978

Viking extended mission support

Deep Space Network support is detailed for Viking spacecraft activities and the Viking command and tracking system. Viking DSN Mark 3 data subsystem implementation related testing is also discussed.

Gillette, R. L.↗

NASA NTRS1978

Viking continuation mission support

The DSN support of Viking spacecraft activities from 1 July through 31 August 1978 is reported. The DSN Viking Command and Tracking support is included.

Gillette, R. L.↗

NASA NTRS1979

Viking continuation mission support

The Deep Space Network (DSN) support Viking spacecraft activities during the period 1 September 1978 through 31 March 1979 is reported. The DSN Viking command and tracking support is included.

Gillette, R. L.↗

NASA NTRS1980

Magnetospheric multiprobes: Investigations and instrumentation

The multiprobe scientific objectives are to: (1) determine the spatial structure of plasma phenomena such as the aurora, convection reversals, and ion troughs; (2) separate spatial and temporal variations in these phenomena; (3) determine field aligned current densities; (4) perform multiple point analysis of particle beams, wave fields, and plasma clouds that are injected into the ionosphere and magnetosphere by Spacelab active experiment facilities. Trade studies described include: instrument accommodations, power, attitude determination, electric field antennas, storage and ejection, thermal control, tracking communications, command and data management, payload and mission specialist support, functional objectives, and orbital analysis.

Burch, J. L.↗

NASA NTRS1981

Application of variable structure system theory to aircraft flight control

The current status of research on the application of variable structure system (VSS) theory to design aircraft flight control systems is summarized. Two aircraft types are currently being investigated: the Augmentor Wing Jet STOL Research Aircraft (AWJSRA), and AV-8A Harrier. The AWJSRA design considers automatic control of longitudinal dynamics during the landing phase. The main task for the AWJSRA is to design an automatic landing system that captures and tracks a localizer beam. The control task for the AV-8A is to track velocity commands in a hovering flight configuration. Much effort was devoted to developing computer programs that are needed to carry out VSS design in a multivariable frame work, and in becoming familiar with the dynamics and control problems associated with the aircraft types under investigation. Numerous VSS design schemes were explored, particularly for the AWJSRA. The approaches that appear best suited for these aircraft types are presented. Examples are given of the numerical results currently being generated.

Calise, A. J.↗

NASA NTRS1982

Deep Space Telecommunications Systems Engineering

Descriptive and analytical information useful for the optimal design, specification, and performance evaluation of deep space telecommunications systems is presented. Telemetry, tracking, and command systems, receiver design, spacecraft antennas, frequency selection, interference, and modulation techniques are addressed.

Yuen, J. H.↗

NASA NTRS1982

Telecommunications systems design

The general configuration of deep space telecommunication systems is reviewed with regard to the design criteria necessary to insure the integrity of the system's telemetry, command, and tracking functions. The signal to noise spectral density ratios that characterize telecommunications performance are defined in terms of the link parameters. For design control, a statistical approach to predict link performance and to assess its uncertainty is described.

Yuen, J. H.↗

NASA NTRS1984

Investigation, development and application of optimal output feedback theory. Volume 2: Development of an optimal, limited state feedback outer-loop digital flight control system for 3-D terminal area operation

This report contains the development of a digital outer-loop three dimensional radio navigation (3-D RNAV) flight control system for a small commercial jet transport. The outer-loop control system is designed using optimal stochastic limited state feedback techniques. Options investigated using the optimal limited state feedback approach include integrated versus hierarchical control loop designs, 20 samples per second versus 5 samples per second outer-loop operation and alternative Type 1 integration command errors. Command generator tracking techniques used in the digital control design enable the jet transport to automatically track arbitrary curved flight paths generated by waypoints. The performance of the design is demonstrated using detailed nonlinear aircraft simulations in the terminal area, frequency domain multi-input sigma plots, frequency domain single-input Bode plots and closed-loop poles. The response of the system to a severe wind shear during a landing approach is also presented.

Broussard, J. R.↗

NASA NTRS1983

Deep space telecommunication systems engineering

Yuen, J. H.↗

NASA NTRS1985

Determining Availability Characteristics of DSN Data Systems Using Discrepancy Report Data

A reasonably economical way was developed to determine availability characteristics of Deep Space Network (DSN) data systems, subsystems, and assemblies using the DSN discrepancy report (DR) data base and DSN operating schedule and history data bases. Operating mean time between failures (OMTBF), operating mean time to restore service (OMTTRS), and operating functional availability (OFA) can be computed by year, by system, by subsystem, by assembly, and by station. The effort required to produce the desired reports is described, specific data on the telemetry, command, and tracking systems are presented, and major contributors to system outages are identified. Future improvements in preparing and analyzing DR data are also outlined to enhance their use in correcting conditions that lead to outages.

Ruskin, A. M.↗

NASA NTRS1986

Adaptive control robustness in flexible aircraft application

This paper presents the application of a model reference adaptive control (MRAC) algorithm to flexible aircraft flight control. The algorithm is an adaptive version of the Command Generator Tracking (CGT) control technique. This technique forces a dynamic system to follow a reduced-order model, allowing it to cope with the problem of unmodeled dynamics. The studies were made via simulation, using for the plant an aircraft dynamic model similar to the B1 bomber. This model is of a large aircraft with a reasonable amount of structural flexibility. In particular, flight configurations were analyzed where the influence of the flexible modes make it difficult to control the aircraft. The results indicate that the algorithm has good robustness properties vis-a-vis unmodeled dynamics and can force the flexible aircraft to follow rigid body responses.

Sanchez, E. N.↗

NASA NTRS1990

Output Control Using Feedforward And Cascade Controllers

Report presents theoretical study of open-loop control elements in single-input, single-output linear system. Focus on output-control (servomechanism) problem, in which objective is to find control scheme that causes output to track certain command inputs and to reject certain disturbance inputs in steady state. Report closes with brief discussion of characteristics and relative merits of feedforward, cascade, and feedback controllers and combinations thereof.

Seraji, Homayoun↗

NASA NTRS1991

Computer-aided design of flight control systems

A computer program is presented for facilitating the development and assessment of flight control systems, and application to a control design is discussed. The program is a computer-aided control-system design program based on direct digital synthesis of a proportional-integral-filter controller with scheduled linear-quadratic-Gaussian gains and command generator tracking of pilot inputs. The FlightCAD system concentrates on aircraft dynamics, flight-control systems, stability and performance, and has practical engineering applications.

Stengel, Robert F.↗