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At least 163 records · Page 9

All sources NASA NTRS DOE OSTI

NASA NTRS1983

The design and development of a mounting and jettison assembly for the shuttle orbiter advanced gimbal system

This paper describes the requirements, design development, and qualification of the mounting and jettison assembly (MJA) which serves as the base structure for the advanced gimbal system (AGS) developed for NASA, Marshall Space Flight Center, for use during shuttle missions. An engineering model of the MJA has been built and subjected to the following testing: stiffness and modal characterization, sine and random vibration, and a jettison function and energy release. A qualitative summary of the results and the problems encountered during testing, together with the design solutions, is presented.

Korzeniowski, E. S.↗

NASA NTRS1983

Spacelab high density digital recorders

The design and performance of the high-density digital recorder (HDDR) developed for use at the NASA centers (KSC, JSC, and GSFC) and at the JPL to store and retrieve 50-Mb/s PCM data streams from the Spacelab experiments are reported. The recording reproduction, and transport requirements are reviewed; and the design solutions adopted in the final version of the HDDR are described, incuding three-position-modulation and Y-phase encoding, microprocessor-controlled automatic bit synchronization and equalization, cyclic-redundancy-check error detection and correction, clock regeneration, data and clock variations, tape-speed control, and EEE-488 remote control. Reliable performance, with bit error rates 1 in 10 to the 10th forward and 1 in 10 to the 9th reverse or better and packing density up to 50 percent greater than that obtainable using conventional codes, is reported after 1.5 years of service.

Blais, R. A.↗

NASA NTRS1985

Orbiter structural design and verification

The space shuttle development program provided the opportunity to challenge many of the established practices and approaches used in prior manned space flight programs. The most significant accomplishments and resulting precedents which emerged during the structural development of the space shuttle and the space shuttle orbiter are reviewed. Innovations in criteria, design solutions, and certification are highlighted, and brief comments on the lessons learned are included. Thermal stress, graphite epoxy moisture, window structure, and structural inspection are discussed under lessons learned.

Glynn, P. C.↗

NASA NTRS1986

Shutter mechanism for calibration of the cryogenic diffused infrared background experiment (DIRBE) instrument

The design requirements, the design, the assembly and alignment, and the test program for a shutter mechanism which must operate at cryogenic temperature and draw less than 1.0 milliwatt are discussed. The design solution to meet these requirements is a device that positions a mirror with repeated accuracy, has no wearing surfaces, and operates at 2.0 K. The unique feature of this device is the simplicity of the mechanism, thus obtaining high reliability.

Tyler, Allen↗

NASA NTRS1987

An orbiting control station for free-flying teleoperators - Preliminary design methodology

This paper summarizes work being done to develop the preliminary design of a control station for the free-flying teleoperator/telerobot ROBIN. The four-step development process involves telerobot capability definition, mission analysis, requirements generation, and design solution. The ROBIN servomanipulator requirements are listed, and a telerobotic control station requirement tree is shown.

Clarke, M. M.↗

NASA NTRS1989

Human factors issues in performing life science experiments in a 0-G environment

An overview of the environmental conditions within the Spacelab and the planned Space Station Freedom is presented. How this environment causes specific Human Factors problems and the nature of design solutions are described. The impact of these problems and solutions on the performance of life science activities onboard Spacelab (SL) and Space Station Freedom (SSF) is discussed. The first area highlighted is contamination. The permanence of SSF in contrast to the two-week mission of SL has significant impacts on crew and specimen protection requirements and, thus, resource utilization. These requirements, in turn impose restrictions on working volumes, scheduling, training, and scope of experimental procedures. A second area is microgravity. This means that all specimens, materials, and apparatus must be restrained and carefully controlled. Because so much of the scientific activity must occur within restricted enclosures (gloveboxes), the provisions for restraint and control are made more complex. The third topic is crewmember biomechanics and the problems of movement and task performance in microgravity. In addition to the need to stabilize the body for the performance of tasks, performance of very sensitive tasks such as dissection is difficult. The issue of space sickness and adaption is considered in this context.

Gonzalez, Wayne↗

NASA NTRS1989

Advanced manned launch systems

Advanced Manned Launch Systems (AMLS) studies underway at the NASA Langley Research Center are described. The AMLS studies have focused on investigating mission needs and identifying technologies, operational requirements, and life-cycle costs. Two-stage vertical take off rocket vehicles with significant levels of reusability are shown to be cost effective for moderate to high flight rates. All-hydrogen fuel vehicles are preferred over methane boosted systems for both operational and cost considerations. Drawings of possible AMLS design solutions are presented. Fully reusable, partially resusable, expendable stage and horizontal take off airbreather/rocket solutions are compared.

Talay, Theodore A.↗

NASA NTRS1990

Automated simulation as part of a design workstation

A development project for a design workstation for advanced life-support systems (called the DAWN Project, for Design Assistant Workstation), incorporating qualitative simulation, required the implementation of a useful qualitative simulation capability and the integration of qualitative and quantitative simulation such that simulation capabilities are maximized without duplication. The reason is that to produce design solutions to a system goal, the behavior of the system in both a steady and perturbed state must be represented. The Qualitative Simulation Tool (QST), on an expert-system-like model building and simulation interface toll called ScratchPad (SP), and on the integration of QST and SP with more conventional, commercially available simulation packages now being applied in the evaluation of life-support system processes and components are discussed.

Cantwell, Elizabeth↗

NASA NTRS1990

Superconducting glass-ceramics in the Bi-Sr-Ca-Cu-O system

Differential thermal analysis, XRD, SEM, and resistivity measurements, have been used to study the recrystallization during various heat treatments of a Bi1.5SrCaCu2O(z) glass obtained by rapid quenching from the melt. Heating at 450 C formed the Bi(2+x)Sr(2-x)-CuO(z) solid solution designated 'R'. Between 765 and 845 C, R reacts slowly with the glass to form the 80 K superconductor Bi2(Sr,Ca)3Cu2O(z), together with CuO. Heating for 7 days at the higher temperature, followed by slow cooling, raised the temperature of zero resistance to 77 K.

De Guire, Mark R.↗

NASA NTRS1988

Sensor deployment mechanism for Surfer satellite

A design is presented for a sensor-deployment mechanism to be used aboard the Surfer satellite, from which scientific instruments will be extended to study the earth ionosphere during the Space Shuttle Tether Experiment. The design discussed uses four folding arms to extend the radial sensors, as well as two storable tubular extendible members or spirally wound self-extending tube booms to project the axial sensors outward. The design solution chosen, a folding arm, is discussed in detail with attention to mechanical operation and component functions. Test program results are presented.

Dill, Robert↗

NASA NTRS1990

A&R challenges for in-space operations

Automation and robotics (A&R) challenges for in-space operations are examined, with emphasis on the interaction between developing requirements, developing solutions, design concepts, and the nature of the applicability of automation in robotic technologies. Attention is first given to the use of A&R in establishing outposts on the moon and Mars. Then emphasis is placed on the requirements for the assembly of transportation systems in low earth orbit. Concepts of the Space Station which show how the assembly, processing, and checkout of systems in LEO might be accommodated are examined.

Underwood, James↗

NASA NTRS1990

Aeroassist Flight Experiment Reaction Control System preliminary design

The Aeroassist Flight Experiment (AFE) has several different flight modes associated with its mission. The effect the spacecraft attitude control system (ACS) has on the Reaction Control System (RCS) requirements for all the flight modes is discussed. The ACS requirements and their consequences on the design of the RCS is then discussed in detail. Special problems in the RCS design unique to the AFE mission and the design solutions to these problems are presented.

Langford, G. K.↗

NASA NTRS1990

Automated simulation as part of a design workstation

A development project for a design workstation for advanced life-support systems incorporating qualitative simulation, required the implementation of a useful qualitative simulation capability and the integration of qualitative and quantitative simulations, such that simulation capabilities are maximized without duplication. The reason is that to produce design solutions to a system goal, the behavior of the system in both a steady and perturbed state must be represented. The paper reports on the Qualitative Simulation Tool (QST), on an expert-system-like model building and simulation interface toll called ScratchPad (SP), and on the integration of QST and SP with more conventional, commercially available simulation packages now being applied in the evaluation of life-support system processes and components.

Cantwell, E.↗

NASA NTRS1990

High performance VLSI telemetry data systems

NASA-Goddard has over the last five years developed generic ground telemetry data system elements addressing the budget limitations-driven demand for greater modularity, flexibility, and interchangeability. These design solutions, which may be characterized as a 'functional components approach', encompasses both hardware and software components; the former involve telemetry application-specific ICs for data rate requirements of up to 300 Mbps, while the latter extend to embedded local software intelligence. Attention is given to the consequences of the functional components approach for VLSI components.

Chesney, J.↗

NASA NTRS1991

ICADS: A cooperative decision making model with CLIPS experts

A cooperative decision making model is described which is comprised of six concurrently executing domain experts coordinated by a blackboard control expert. The focus application field is architectural design, and the domain experts represent consultants in the area of daylighting, noise control, structural support, cost estimating, space planning, and climate responsiveness. Both the domain experts and the blackboard were implemented as production systems, using an enhanced version of the basic CLIPS package. Acting in unison as an Expert Design Advisor, the domain and control experts react to the evolving design solution progressively developed by the user in a 2-D CAD drawing environment. A Geometry Interpreter maps each drawing action taken by the user to real world objects, such as spaces, walls, windows, and doors. These objects, endowed with geometric and nongeometric attributes, are stored as frames in a semantic network. Object descriptions are derived partly from the geometry of the drawing environment and partly from knowledge bases containing prototypical, generalized information about the building type and site conditions under consideration.

Pohl, Jens↗

NASA NTRS1992

Aeroelastic optimization of an advanced geometry helicopter rotor

Sensitivity derivatives of blade loads and aeroelastic stability of a helicopter rotor in forward flight are calculated as an integral part of a basic aeroelastic analysis using a direct analytical approach. Design variables include nonstructural mass and its placement, chordwise offset of blade center of gravity and aerodynamic center from the elastic axis, blade bending stiffnesses (flap, lag, torsion), and tip geometry (sweep, anhedral, pretwist and planform taper). By means of a sensitivity study, the importance of different design variables on oscillatory hub loads and damping of blade modes is examined. Aeroelastic and sensitivity analyses of the rotor based on a finite element method in space and time are linked with automated optimization algorithms to perform optimization studies of rotor blades. Optimum design solutions, calculated for a four-bladed, soft-inplane hingeless rotor achieved a reduction of 25-60 percent of all 4/rev loads.

Ganguli, Ranjan↗

NASA NTRS1992

Operability of Space Station Freedom's meteoroid/debris protection system

The design of Space Station Freedom's external structure must not only protect the spacecraft from the hazardous environment, but also must be compatible with the extra vehicular activity system for assembly and maintenance. The external procedures for module support are utility connections, external orbital replaceable unit changeout, and maintenance of the meteoroid/debris shields and multilayer insulation. All of these interfaces require proper man-machine engineering to be compatible with the extra vehicular activity and manipulator systems. This paper discusses design solutions, including those provided for human interface, to the Space Station Freedom meteoroid/debris protection system. The system advantages and current access capabilities are illustrated through analysis of its configuration over the Space Station Freedom resource nodes and common modules, with emphasis on the cylindrical sections and endcones.

Kahl, Maggie S.↗

NASA NTRS1992

Classical and adaptive control algorithms for the solar array pointing system of the Space Station Freedom

Classical and adaptive control algorithms for the solar array pointing system of the Space Station Freedom are designed using a continuous rigid body model of the solar array gimbal assembly containing both linear and nonlinear dynamics due to various friction components. The robustness of the design solution is examined by performing a series of sensitivity analysis studies. Adaptive control strategies are examined in order to compensate for the unfavorable effect of static nonlinearities, such as dead-zone uncertainties.

Ianculescu, G. D.↗