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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 1,009 records · Page 56

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NASA NTRS1990

Preliminary analysis of SSME baseline plume emissions

A review of current efforts to establish baseline emission levels from the SSME plume is presented. Recent data obtained under the Optical Plume Anomaly Detector program at the Technology Test Bed at MSFC is examined with an emphasis on interpretation of spectral and temporal features observed during nominal motor operation. In particular, the repeated appearance of Cr, Fe, Mn, Ca, and Li at engine startup and shutdown is discussed, and broadband attenuation due to scattering from water vapor is seen to complicate characterization of baseline levels. Also, emission from the combustion related specie OH, the underlying broadband continuum, and the Na impurity is discussed in relation to changes in Rated Power Level (RPL). Results from a theoretical spectral analysis of engine start-up activity is presented.

Wallace, T. L.↗

NASA NTRS1990

Heat flux measurement in SSME turbine blade tester

Surface heat flux values were measured in the turbine blade thermal cycling tester located at NASA-Marshall. This is the first time heat flux has been measured in a space shuttle main engine turbopump environment. Plots of transient and quasi-steady state heat flux data over a range of about 0 to 15 MW/sq m are presented. Data were obtained with a miniature heat flux gage device developed at NASA-Lewis. The results from these tests are being incorporated into turbine design models. Also, these gages are being considered for airfoil surface heat flux measurement on turbine vanes mounted in SSME turbopump test bed engine nozzles at Marshall. Heat flux effects that might be observed on degraded vanes are discussed.

Liebert, Curt H.↗

NASA NTRS1991

On-orbit damage detection and health monitoring of large space trusses - Status and critical issues

The literature in the fields of structural identification, mode shape expansion and orthogonalization, and on-orbit damage location of large space trusses is reviewed. The use of a Dynamic Scale Model Technology (DSMT) hybrid scale model for damage location research and as a universal test bed for other damage location methods is proposed as a means of comparing and evaluating existing and newly developed methods in the named areas. Issues concerning on-orbit data acquisition, data accuracy, and data quality relevant to structural dynamic system identification which require extensive research are identified.

Kashangaki, Thomas A.-L.↗

NASA NTRS1990

Automated electric power management and control for Space Station Freedom

A comprehensive automation design is being developed for Space Station Freedom's electric power system. It strives to increase station productivity by applying expert systems and conventional algorithms to automate power system operation. An integrated approach to the power system command and control problem is defined and used to direct technology development in: diagnosis, security monitoring and analysis, battery management, and cooperative problem-solving for resource allocation. The prototype automated power system is developed using simulations and test-beds.

Dolce, James L.↗

NASA NTRS1991

Dynamic Isotope Surface Power Systems

The Dynamic Isotope Power Systems (DIPS) demonstration program, sponsored by the U.S. Department of Energy (DOE) with support funding from the National Aeronautics and Space Administration (NASA), is currently focused on the development of a standardized 2.5 kWe portable generator for multiple applications on the lunar or Martian surface. A variety of potential remote and mobile applications has been identified by NASA including surface rovers for both short and extended duration missions, remote power to science packages, and backup to central base power. Recent work focused on refining the 2.5 kWe design including assessing compatibility with the Martian environment to assure the design is suitable while imposing only a minor mass penalty on lunar operations. Additional work included a study performed to compare the DIPS with regenerative fuel cell systems for lunar mobile and remote power systems. Power requirements were reviewed and a modular system chosen for the comparison. Finally, a plan and cycle schematic were generated for an early demonstration of a prototypic isotope power Brayton system using the Antarctic as the test bed.

Hunt, Maribeth E.↗

NASA NTRS1991

Hypersonic flows as related to the National Aerospace plane

Experimental data for a series of 2-D and 3-D shock wave/boundary layer interaction flows at Mach 8.2 are presented. The test bodies, composed of simple geometric shapes fastened to a flat plate test bed, were designed to generate flows with varying degrees of pressure gradient, boundary layer separation, and turning angle. The data include surface pressure and heat transfer distributions as well as limited mean flowfield surveys both in the undisturbed and interaction regimes. The data are presented in a convenient form to be used to validate existing or future computational models of these hypersonic flows.

Kussoy, Marvin↗

NASA NTRS1991

Real Time Data System (RTDS)

Information is given in viewgraph form on the Real Time Data System (RTDS). The goals are to increase the quality of flight decision making, reduce and enhance flight controller training time, and serve as a near-operations technology test-bed. Information is given on the growth of RTDS; flight control disciplines; RTDS technology deployment in 1987-1989 and 1990-91; a functionality comparison of mainframes and workstations; and technology transfer activities.

Heindel, Troy A.↗

NASA NTRS1991

Advanced technologies for Mission Control Centers

Advance technologies for Mission Control Centers are presented in the form of the viewgraphs. The following subject areas are covered: technology needs; current technology efforts at GSFC (human-machine interface development, object oriented software development, expert systems, knowledge-based software engineering environments, and high performance VLSI telemetry systems); and test beds.

Dalton, John T.↗

NASA NTRS1991

Flexible digital modulation and coding synthesis for satellite communications

An architecture and a hardware prototype of a flexible trellis modem/codec (FTMC) transmitter are presented. The theory of operation is built upon a pragmatic approach to trellis-coded modulation that emphasizes power and spectral efficiency. The system incorporates programmable modulation formats, variations of trellis-coding, digital baseband pulse-shaping, and digital channel precompensation. The modulation formats examined include (uncoded and coded) binary phase shift keying (BPSK), quatenary phase shift keying (QPSK), octal phase shift keying (8PSK), 16-ary quadrature amplitude modulation (16-QAM), and quadrature quadrature phase shift keying (Q squared PSK) at programmable rates up to 20 megabits per second (Mbps). The FTMC is part of the developing test bed to quantify modulation and coding concepts.

Vanderaar, Mark↗

NASA NTRS1991

Fluid management technology: Liquid slosh dynamics and control

Flight experiments were defined for the Cryogenic On-Orbit Liquid Depot Storage, Acquisition and Transfer Satellite (COLD-SAT) test bed satellite and the Shuttle middeck to help establish the influence of the gravitational environment on liquid slosh dynamics and control. Several analytical and experimental studies were also conducted to support the experiments and to help understand the anticipated results. Both FLOW-3D and NASA-VOF3D computer codes were utilized to simulate low Bond number, small amplitude sloshing, for which the motions are dominated by surface forces; it was found that neither code provided a satisfactory simulation. Thus, a new analysis of low Bond number sloshing was formulated, using an integral minimization technique that will allow the assumptions made about surface physics phenomena to be modified easily when better knowledge becomes available from flight experiments. Several examples were computed by the innovative use of a finite-element structural code. An existing spherical-pendulum analogy of nonlinear, rotary sloshing was also modified for easier use and extended to low-gravity conditions. Laboratory experiments were conducted to determine the requirements for liquid-vapor interface sensors as a method of resolving liquid surface motions in flight experiments. The feasibility of measuring the small slosh forces anticipated in flight experiments was also investigated.

Dodge, Franklin T.↗

NASA NTRS1992

Vibration attenuation of the NASA Langley evolutionary structure experiment using H(sub infinity) and structured singular value (micron) robust multivariable control techniques

The use is studied of active control to attenuate structural vibrations of the NASA Langley Phase Zero Evolutionary Structure due to external disturbance excitations. H sub infinity and structured singular value (mu) based control techniques are used to analyze and synthesize control laws for the NASA Langley Controls Structures Interaction (CSI) Evolutionary Model (CEM). The CEM structure experiment provides an excellent test bed to address control design issues for large space structures. Specifically, control design for structures with numerous lightly damped, coupled flexible modes, collocated and noncollocated sensors and actuators and stringent performance specifications. The performance objectives are to attenuate the vibration of the structure due to external disturbances, and minimize the actuator control force. The control design problem formulation for the CEM Structure uses a mathematical model developed with finite element techniques. A reduced order state space model for the control design is formulated from the finite element model. It is noted that there are significant variations between the design model and the experimentally derived transfer function data.

Balas, Gary J.↗

NASA NTRS1992

Software architecture for a distributed real-time system in Ada, with application to telerobotics

The architecture structure and software design methodology presented is described in the context of telerobotic application in Ada, specifically the Engineering Test Bed (ETB), which was developed to support the Flight Telerobotic Servicer (FTS) Program at GSFC. However, the nature of the architecture is such that it has applications to any multiprocessor distributed real-time system. The ETB architecture, which is a derivation of the NASA/NBS Standard Reference Model (NASREM), defines a hierarchy for representing a telerobot system. Within this hierarchy, a module is a logical entity consisting of the software associated with a set of related hardware components in the robot system. A module is comprised of submodules, which are cyclically executing processes that each perform a specific set of functions. The submodules in a module can run on separate processors. The submodules in the system communicate via command/status (C/S) interface channels, which are used to send commands down and relay status back up the system hierarchy. Submodules also communicate via setpoint data links, which are used to transfer control data from one submodule to another. A submodule invokes submodule algorithms (SMA's) to perform algorithmic operations. Data that describe or models a physical component of the system are stored as objects in the World Model (WM). The WM is a system-wide distributed database that is accessible to submodules in all modules of the system for creating, reading, and writing objects.

Olsen, Douglas R.↗

NASA NTRS1991

A space crane concept for performing on-orbit assembly

The topics are presented in viewgraph form and include: in-space assembly and construction enhances future mission planning flexibility; in-space assembly and construction facility concept; space crane concept with mobile base; fundamental characteristics; space crane research approach; spacecraft component positioning and assembly test-bed; and articulating joint testbed.

John T Dorsey↗

NASA NTRS1992

A generalized reusable guidance algorithm for optimal aerobraking

A practical real-time guidance algorithm was developed for guiding aerobraking vehicles in such a way that the maximum heating rate, the maximum structural loads, and the post-aeropass delta-V requirements (for post-aeropass orbit insertion) are all minimized. The algorithm is general and reusable in the sense that a minimum of assumptions are made, thus minimizing the number of gains and mission-dependent parameters that must be laboriously determined prior to a particular mission. A particularly interesting feature is that inplane guidance performance is tuned by simply adjusting one mission-dependent parameter, the bank margin; similarly, the out-of-plane guidance performance is turned by simply adjusting a plane controller time constant. Other objectives in the algorithm development are simplicity, efficiency, and ease of use. The algorithm is developed for, but not necessarily restricted to, a single pass mission and a trimmed vehicle with a bank angle modulation as the method of trajectory control. Guidance performance is demonstrated via results obtained using this algorithm integrated into an aerobraking test-bed program. Comparisons are made with numerical results from a version of the aerobraking guidance algorithm that was to be flown onboard NASA's aeroassist flight experiment (AFE) vehicle. Promising results are obtained with a minimum of development effort.

Dukeman, G. A.↗

NASA NTRS1992

The e-Beam Sustained Laser Technology for Space-based Doppler Wind Lidar

An overview is presented of GEC Avionics activities relating to the Spaceborne Doppler Wind Lidar. In particular, the results of design studies into the use of an e-beam sustained CO2 laser for spaceborne applications, and experimental work on a test bed system are discussed.

Brown, M. J.↗

NASA NTRS1992

The Lidar In-Space Technology Experiment (LITE)

The primary goals of the Lidar In-Space Technology Experiment (LITE) are to demonstrate the maturity of space-based lidar technology, to provide some unique measurements, and to provide a platform for the development of technology for future space-based systems. LITE is currently scheduled to fly on the Shuttle in early 1994. Approval has recently been given for the first of several planned follow-on missions at 2-year intervals. The first mission will be used to develop experience in operating a lidar system in a space environment and to evaluate the sensitivity of the instrument for performing scientific studies. The second mission will focus on scientific studies of clouds, aerosols, and the middle atmosphere. On subsequent follow-on missions, LITE will be used as a test bed for demonstrating more advanced measurement capabilities.

Mccormick, M. Patrick↗

NASA NTRS1991

Aging aircraft NDI Development and Demonstration Center (AANC): An overview

A major center with emphasis on validation of nondestructive inspection (NDI) techniques for aging aircraft, the Aging Aircraft NDI Development and Demonstration Center (AANC), has been funded by the FAA at Sandia National Laboratories. The Center has been assigned specific tasks in developing techniques for the nondestructive inspection of static engine parts, assessing inspection reliability (POD experiments), developing testbeds for NDI validation, maintaining a FAA library of characterized aircraft structural test specimens, and leasing a hangar to house a high flight cycle transport aircraft for use as a full scale test bed.

Aging Aircraft↗

NASA NTRS1992

High-speed civil transport issues and technology program

A strawman program plan is presented, consisting of technology developments and demonstrations required to support the construction of a high-speed civil transport. The plan includes a compilation of technology issues related to the development of a transport. The issues represent technical areas in which research and development are required to allow airframe manufacturers to pursue an HSCT development. The vast majority of technical issues presented require flight demonstrated and validated solutions before a transport development will be undertaken by the industry. The author believes that NASA is the agency best suited to address flight demonstration issues in a concentrated effort. The new Integrated Test Facility at NASA Dryden Flight Research Facility is considered ideally suited to the task of supporting ground validations of proof-of-concept and prototype system demonstrations before night demonstrations. An elaborate ground hardware-in-the-loop (iron bird) simulation supported in this facility provides a viable alternative to developing an expensive fill-scale prototype transport technology demonstrator. Drygen's SR-71 assets, modified appropriately, are a suitable test-bed for supporting flight demonstrations and validations of certain transport technology solutions. A subscale, manned or unmanned flight demonstrator is suitable for flight validation of transport technology solutions, if appropriate structural similarity relationships can be established. The author contends that developing a full-scale prototype transport technology demonstrator is the best alternative to ensuring that a positive decision to develop a transport is reached by the United States aerospace industry.

Hewett, Marle D.↗