Postflight hardware evaluation 360T025 (RSRM-25, STS-46). Appendix C: Nozzle PFORs
The final Postflight Hardware Evaluation Report 360T025, Appendix C is presented. The Postflight Observation Records (PFOR's) for nozzles is provided.
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Postflight hardware evaluation 360T025 (RSRM-25, STS-46). Appendix E: Insulation postfire data
The final Postflight Hardware Evaluation Report 360T025, Appendix E is presented. The insulation postfire data is included. Insulation performance is addressed.
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Postflight hardware evaluation 360T025 (RSRM-25, STS-46). Appendix D: Nozzle postfire data
The final Postflight Hardware Evaluation Report 360T025, Appendix D is provided. Nozzle postfire data are included. Char and erosion data are provided.
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Design and test hardware for a solar array switching unit
This paper describes the control of a pulse width modulated (PWM) type sequential shunt switching unit (SSU) for spacecraft applications. It is found that the solar cell output capacitance has a significant impact on SSU design. Shorting of this cell capacitance by the PWM switch causes input current surges. These surges are minimized by the use of a series filter inductor. The system with a filter is analyzed for ripple and the control to output-voltage transfer function. Stable closed loop design considerations are discussed. The results are supported by modeling and measurements of loop gain and of closed-loop bus impedance on test hardware for NASA's 120 V Earth Observation System (EOS). The analysis and modeling are also applicable to NASA's 160 V Space Station power system.
Patil, A. R.↗
Dual control vibration tests of flight hardware
A vibration retest of a spacecraft flight instrument, the Mars Observer Camera (MOC), was conducted using extremal dual control to automatically limit the shaker force and notch the shaker acceleration at resonances. This was the first application of extremal dual control with flight hardware at JPL. The retest was successful in that the environment was representative of flight plus some margin, the instrument survived without any structural or performance degradation, and the force limiting worked very well. The test set-up, force limiting procedure, and test results are described herein. It is concluded that dual control should be utilized when there is a concern about overtesting in hard-base-drive tests and the instrumentation for force measurement and control is available. Recommendations for improving the implementation of dual control are provided as a result of this first experience.
Scharton, Terry D.↗
Tests characterizing bioprocessor hardware for analytical modeling
The tests outlined in this paper were used to characterize the hardware components of the Salad Machine, a small NASA-developed bioprocessor. The data from these tests are presented, and the methods by which this data can be integrated into system mathematical models are briefly discussed. The subsystems and physical processes discussed include the lighting system, the air loop (condensing heat exchanger and the blower), heat transfer to the surroundings, and leakage. Through this effort it was learned that in the development of a test protocol, care should be taken to order the tests such that environmental parameters, particularly humidity, require as few large adjustments as possible. Sensor calibration and installation take a substantial amount of time, which should be built into the test schedule. Two properties were particularly hard to quantify: the air flow rate and the energy from the lighting system entering into the growth volume. Flow rate can be measured using the appropriate device for the system configuration and airflow. Lighting system radiation level was measured using three methods. The results of these methods varied substantially, putting off conclusive quantification of this value.
Gustavino, S.↗
Plasma arc welding repair of space flight hardware
Repair and refurbishment of flight and test hardware can extend the useful life of very expensive components. A technique to weld repair the main combustion chamber of space shuttle main engines has been developed. The technique uses the plasma arc welding process and active cooling to seal cracks and pinholes in the hot-gas wall of the main combustion chamber liner. The liner hot-gas wall is made of NARloyZ, a copper alloy previously thought to be unweldable using conventional arc welding processes. The process must provide extensive heat input to melt the high conductivity NARloyZ while protecting the delicate structure of the surrounding material. The higher energy density of the plasma arc process provides the necessary heat input while active water cooling protects the surrounding structure. The welding process is precisely controlled using a computerized robotic welding system.
Hoffman, David S.↗
Formal hardware verification of digital circuits
The use of formal methods to verify the correctness of digital circuits is less constrained by the growing complexity of digital circuits than conventional methods based on exhaustive simulation. This paper briefly outlines three main approaches to formal hardware verification: symbolic simulation, state machine analysis, and theorem-proving.
Joyce, J.↗
Correctness properties for iterated hardware structures
Iterated structures occur frequently in hardware. This paper describes properties required of mathematical relations that can be implemented iteratively and demonstrates the use of these properties on a generalized class of adders. This work provides a theoretical basis for the correct synthesis of iterated arithmetic structures.
Windley, Phillip J.↗
Postflight hardware evaluation RSRM-29 (STS-54). Appendix D: Nozzle postfire data
Appendix D, Nozzle Postfire Data of the Final Postflight Hardware Evaluation Report RSRM-29 (STS-54) is provided. Data on the erosion and char of the following are included: forward exit cone assembly, throat assembly, nose inlet, cowl/OBR, fixed housing assembly and aft exit cone assembly.
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Postflight hardware evaluation RSRM-29 (STS-54). Appendix C: Nozzle PFORs
Appendix C, Nozzle Postflight Observation Records (PFOR's) for the Final Postflight Hardware Evaluation Report RSRM-29 (STS-54) is provided. PFOR data are included on: nozzle joint condition; nose inlet-to-throat joint condition; and nozzle subassembly phenolic bondline condition.
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Postflight hardware evaluation RSRM-29 (STS-54). Appendix E: Insulation postfire data
Appendix E, Insulation Postfire Data for the Final Postflight Hardware Evaluation Report RSRM-29 (STS-54) is provided. Data on the following are included: nozzle-to-case joint performance; aft dome insulation performance; aft cylinder insulation performance; forward segment star tip insulation performance; and igniter chamber and adapter insulation performance.
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Postflight Hardware Evaluation Report RSRM-29 (STS-54). Case, Seals, and Joints PFORs, Appendix B
Appendix B, Case, Seals, and Joints Postflight Observation Records (PFOR's) for the Final Postflight Hardware Evaluation Report for RSRM-29 (STS-54) is included.
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Hardware design of a grappling/docking device accommodating large lateral and angular misalignments
In this hardware project, continued from last year, the students developed ideas for a new grappling and docking mechanism that would be able to accommodate a very large initial misalignment (up to one half of the spacecraft radius) and simultaneously a large angular misalignment (up to 20 degrees) between space tug and space vehicle. The students were made familiar with the project by visiting TRW, where they could study the prototype of the NASA Orbiting Maneuvering Vehicle (OMV, since canceled). The students' objective was to design a model, built in the University machine shop, that would demonstrate the potential for much larger misalignments than was possible with the OMV.
Baker, Myles↗
Hardware design of a spherical mini-rover
In this hardware project the students designed the prototype of a novel mini-rover for the exploration of a planetary surface. In an actual application, a large number of such miniature roving devices would be released from a landing craft. Each rover would be equipped with a Cd 109 radio-isotope source (a gamma ray emitter) irradiating the planetary surface below the rover, and an x-ray fluorescence detector for a quantitative assay of high atomic weight elements in the planet's surface. (Similar, miniaturized, hand-held devices have recently been developed for use in gold mines). The device developed by the students was limited to demonstrating the mechanical and electrical drive. The geometric external shape is a sphere; hence there is no danger of the rover being turned on its back and stopped. Propulsion is by means of an interior mass, eccentric to the sphere and driven by an electric motor. In an inter-disciplinary effort in mechanical and electrical engineering, the students designed the mechanical parts, built the transistorized circuit board, and tested the device.
Tarlton, John↗
Streamlined design and self reliant hardware for active control of precision space structures
Precision space structures may require active vibration control to satisfy critical performance requirements relating to line-of-sight pointing accuracy and the maintenance of precise, internal alignments. In order for vibration control concepts to become operational, it is necessary that their benefits be practically demonstrated in large scale ground-based experiments. A unique opportunity to carry out such demonstrations on a wide variety of experimental testbeds was provided by the NASA Control-Structure Integration (CSI) Guest Investigator (GI) Program. This report surveys the experimental results achieved by the Harris Corporation GI team on both Phases 1 and 2 of the program and provides a detailed description of Phase 2 activities. The Phase 1 results illustrated the effectiveness of active vibration control for space structures and demonstrated a systematic methodology for control design, implementation test. In Phase 2, this methodology was significantly streamlined to yield an on-site, single session design/test capability. Moreover, the Phase 2 research on adaptive neural control techniques made significant progress toward fully automated, self-reliant space structure control systems. As a further thrust toward productized, self-contained vibration control systems, the Harris Phase II activity concluded with experimental demonstration of new vibration isolation hardware suitable for a wide range of space-flight and ground-based commercial applications.The CSI GI Program Phase 1 activity was conducted under contract NASA1-18872, and the Phase 2 activity was conducted under NASA1-19372.
Hyland, David C.↗
Dynamic Stability Instrumentation System (DSIS). Volume 1: Hardware description
This paper is a hardware description manual for the Dynamic Stability Instrumentation System that is used in specific NASA Langley wind tunnels. The instrumentation system performs either a synchronous demodulation or a fast Fourier transform on dynamic balance strain gage signals, and ultimately computes aerodynamic coefficients. The DSIS consists of a double rack of instruments, a remote motor-generator set, two special stings each with motor driven shafts, and specially designed balances. The major components in the instrumentation rack include a personal computer, digital signal processor microcomputers, computer-controlled signal conditioners, function generator, digital multimeter, and an optional fast Fourier transform analyzer.
Jordan, T. L.↗
Mir hardware heritage
The heritage of the major Mir complex hardware elements is described. These elements include Soyuz-TM and Progress-M; the Kvant, Kvant 2, and Kristall modules; and the Mir base block. Configuration changes and major mission events of the Salyut 6, Salyut 7, and Mir multiport space stations are described in detail for the period 1977-1994. A comparative chronology of U.S. and Soviet/Russian manned spaceflight is also given for that period. The 68 illustrations include comparative scale drawings of U.S. and Russian spacecraft as well as sequential drawings depicting missions and mission events.
Mir Space Station↗