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Technical Paper

User Interface Integration for Space Station Freedom

1993-07-01
932038
The unique development environment of NASA's Space Station Freedom (SSF) creates numerous challenges to the design of a common user interface for operating the spacecraft. Astronauts on board SSF will utilize multi-purpose workstations as their primary command and control interface to the vehicle. With the exception of some dedicated hardware controls, the vast majority of the workstation user interface will be implemented in software. The specification and design of the SSF user interface requires the synthesis of on-orbit operational requirements with multiple systems' functional requirements, all of which emanate from geographically and organizationally distributed entities. Human factors requirements as well as constraints imposed by the SSF Displays and Controls (D&C) system architecture are additional considerations.
Technical Paper

Time Domain Design/Analysis Tool for the MIL-STD-1553B Data Bus

1994-11-01
942551
This paper describes the capabilities of using a time domain analysis to simulate the electrical waveforms on the MIL-STD-1553B data bus using the circuit simulation program SPICE. This simulation was developed to analyze the various data bus architectures of the Space Station Freedom (SSF) propulsion module system. The advantages of this model over frequency domain models is that the waveform is directly calculated, not synthesized, providing a more accurate and detailed waveform representation. Also, nonstandard configurations and effects can be modeled with accurate simulation results. The output of the simulation is an electrical waveform which can be measured at any point in the bus architecture. Therefore it is possible to see the distortion effects on the transmitted signal's waveform at any point on the MIL-STD-1553B data bus. This model accurately simulates the stray impedance effects of all bus components, and is flexible enough to examine any transmitted waveform.
Technical Paper

The KEEP EAGLE F-15E High Angle-of-Attack Flight Test Program

1996-10-01
965574
The KEEP EAGLE flight test program was conducted from August 1994 until August 1995 at Edwards AFB by a combined government/contractor test team to evaluate improvements to F-15E high angle-of-attack and spin recovery characteristics. This paper will trace the program from its inception in 1992 until conclusion in 1995, with emphasis on the test approach and flight test techniques employed for this high risk program. Specifically, the test approach included novel assessments of spin recovery control power early in the flight test program using controlled build-ups in yaw rate. The program also used simulation effectively to improve test efficiency and maintain test team proficiency with normal and emergency procedures. These techniques allowed a relatively aggressive flight test program without compromising safety. A total of 18 different aircraft configurations were successfully tested, with 146 developed spins completed throughout the course of 81 program flights.
Technical Paper

Statistical Process Control: Real-Time Data Acquisition and Response

1994-10-01
941840
The paper describes the development, implementation, and benefits of a real-time statistical process control (SPC) data acquisition and response system. The system has been installed on four production CNC riveters and provides enhanced, in-process control of automated fastening machine performance. Each system employs commercially available SPC components. These components, coupled with real-time data acquisition computers, have been integrated with the riveter's controllers and sensors to detect process anomalies as they occur. Real-time knowledge of fastening machine performance is the benefit of this system's approach to SPC. Fastener quality is ensured during the fastening cycle, not after sequences (and perhaps hundreds of rivets) have been completed.
Technical Paper

Spacecraft Fire Detection and Suppression (FDS) Systems: An Overview and Recommendations for Future Flights

1993-07-01
932166
As manned spacecraft have evolved into larger and more complex configurations, the mandate for preventing, detecting, and extinguishing on-board fires has grown proportionately to ensure the success of progressively ambitious missions. The closed environment and high value of manned spacecraft offer the Fire Detection and Suppression (FDS) systems designer significant challenges. With the presence of Oxygen (O2), flammable materials, and ignition sources, it is impossible to completely remove the likelihood of a spacecraft fire. Manned spacecraft contain these three ingredients for fire; therefore, it becomes profitable to review past designs of FDS systems and ground testing to determine system performance and lessons learned in the past for present and future applications.
Technical Paper

Space Station Freedom Resource Nodes Internal Thermal Control System

1993-07-01
932148
This paper presents an overview of the design and operation of the internal thermal control system (ITCS) developed for Space Station Freedom by the NASA-Johnson Space Center and McDonnell Douglas Aerospace to provide cooling for the resource nodes, airlock, and pressurized logistics modules. The ITCS collects, transports, and rejects waste heat from these modules by a dual-loop, single-phase water cooling system. ITCS performance, cooling, and flow rate requirements are presented. An ITCS fluid schematic is shown and an overview of the current baseline system design and its operation is presented. Assembly sequence of the ITCS is explained as its configuration develops from Man Tended Capability (MTC), for which node 2 alone is cooled, to Permanently Manned Capability (PMC) where the airlock, a pressurized logistics module, and node 1 are cooled, in addition to node 2.
Technical Paper

Space Station Freedom Flow-Through Radiator Testing and Analysis

1993-07-01
932230
The National Aeronautics and Space Administration (NASA) Space Station Freedom (SSF) will use Flow-Through Radiators (FTRs) to reject waste heat that is collected from the on-board Heat Acquisition Devices (HADs). The waste heat is sent to the FTRs via the Pump Module Assembly (PMA) subsystem of the External Active Thermal Control System (EATCS). Two developmental FTR panels were integrated with the EATCS Ground Test Article (GTA). The integrated components were investigated under a thermal/vacuum environment in Thermal/Vacuum Chamber A at NASA/JSC during June, 1992. A detailed SINDA/FLUINT FTR model was developed to predict the steady-state thermal/hydraulic performance of the FTRs. A simplified SINDA/FLUINT FTR model was also developed for use in the GTA integrated model. Schematics and plots comparing the test data and model results are presented for both steady-state and transient conditions.
Technical Paper

Space Constructible Radiator (SCR) Life Test Heat Pipe Performance Testing and Evaluation

1994-06-01
941437
The Space Constructible Radiator (SCR) Life Test heat pipe performance testing is currently conducted at NASA/Johnson Space Center as part of the Advanced Technology Development Program. The SCR is a dual passage, monogroove heat pipe radiator designed and manufactured by Grumman Aerospace for NASA. The heat pipe has many aerospace applications since it can transport a large amount of heat with a compact lightweight design. As the micro-meteoroid/orbital debris environment worsens, it may be advantageous to add the heat pipe radiator to the Space Station's thermal control system. The SCR Life Test has been operating over the last 10 years and will continue until the year 2000. The overall heat transfer coefficient has decreased from 792 W/K (1500 Btu/Hr-°F) to 475 W/K (900 Btu/Hr-°F) but appears to have stabilized. This paper summarizes the SCR Life Test setup and the test results to date.
Technical Paper

SAWD II Subsystem Integration into the Variable Pressure Growth Chamber: A Systems Level Analysis Using CASE/A

1994-06-01
941451
The NASA Johnson Space Center has plans to integrate a Solid Amine Water Desorbed (SAWD II) carbon dioxide removal subsystem into the Variable Pressure Growth Chamber (VPGC). The SAWD II subsystem will be used to remove any excess carbon dioxide (CO2) input into the VPGC which is not assimilated by the plants growing in the chamber. An analysis of the integrated VPGC-SAWD II system was performed using a mathematical model of the system implemented in the Computer-Aided System Engineering and Analysis (CASE/A) package. The analysis consisted of an evaluation of the SAWD II subsystem configuration within the VPGC, the planned operations for the subsystem, and the overall performance of the subsystem and other VPGC subsystems. Based on the model runs, recommendations were made concerning the SAWD II subsystem configuration and operations, and the chambers' automatic CO2 injection control subsystem.
Technical Paper

Operations and Staff Support for Chamber Testing of Advanced Life Support Systems

1995-07-01
951487
The successes of the long-duration MDA/NASA test programs for advanced life-support systems conducted prior to 1971 were highly dependent on the selection and training of both the test crews that remained inside the test chamber throughout the test periods and the outside operating staff. The operating staff was responsible for overall test performance, crew safety monitoring, operation and maintenance of the test facilities, and collection and maintenance of data. A selection, training, and certification program was developed and performed to ensure operating staff members had the correct technical skills and could work effectively together with the inside crew. A training program was designed to ensure that each selected operating staff member was capable of performing all assigned functions and was sufficiently cross-trained to serve at other positions on a contingency basis, if needed.
Technical Paper

Modeling and Validation of the Ambient and Variable Pressure Growth Chamber Models

1993-07-01
932171
The development of regenerative life support systems (RLSS) to support long duration manned space exploration is of great importance. To design future chambers effectively, it is necessary to model both chamber performance and plant growth in current systems. The Johnson Space Center RLSS test bed, which consists of the Variable Pressure Growth Chamber (VPGC) and the Ambient Pressure Growth Chamber (APGC), is a facility that is being used to investigate plant growth and support hardware integration. Detailed and simplified models of the VPGC and APGC have been developed to investigate system performance and response to changes in loading as well as to study long-term plant growth under varying environmental conditions, including temperature, light level, CO2 level, dew point or relative humidity, and photoperiod. To support these studies, models of two crops, lettuce and wheat, have also been developed and integrated into the detailed and simplified simulations of each chamber.
Technical Paper

Microgravity Payload Vibration Isolation System Development

1994-06-01
941416
The objective of this paper is to present results of MDA's payload vibration isolation system research and development program. A unique isolation system with passive or active capabilities designed to provide isolation down to 10-6 g was developed and tested in our 1-g testbed under simulated microgravity conditions. Fluid and electrical umbilicals are also included in the system. The established isolation system performance requirements were met and the testbed data were used to refine our analytical models for predicting flight performance. Simulations using an updated Space Station configuration showed that the payload microgravity requirement can be met by upgrading the hardware from laboratory to flight tolerances and improving the control system design. The next step is to flight test the systems verified in 1 g on the STS/SPACEHAB using a middeck locker size development unit.
Technical Paper

Lunar Base Life Support System and Site Selection

1994-06-01
941457
The selection of a life support system for a lunar base depends on many interrelated factors, both programmatic and technical. Many factors are identifiable through the application of a systems engineering approach to the lunar base design, in which base and mission requirements are determined. In addition, there is a range of evolving technology options whose cost and maturity affect their potential for inclusion in base designs. Results of ongoing lunar base design are presented with emphasis on the selection of promising approaches for advanced life support systems that decrease overall cost for a single, permanently inhabited lunar base. We identify critical technology areas that inhibit the selection of closed life support systems and propose alternative basing scenarios to alleviate development and operational costs. In particular, we quantify the cost savings associated with establishing a base at a lunar pole in a region of permanent sunlight.
Technical Paper

Laser Positioning System for Advanced Composites Lay-Up, Delta III Payload Fairing

1997-06-01
972198
The McDonnell Douglas Delta family of launch vehicles, in its more than 30-year history, has proven to be the most reliable spacecraft deployment platform for both the US government and the private sector. This success is due to the continuous and focused application of advanced, affordable engineering and manufacturing technologies in all stages of the design, fabrication, assembly, quality assurance, and launch. One of the recent technological breakthroughs that has enhanced the Delta's service capabilities is the development and use of large composite structures in critical components. Among these structures is the payload fairing, which acts as a protective shroud for the spacecraft. Traditional composite manufacturing techniques, however, are very labor-intensive and time-consuming.
Technical Paper

Integrated Failure Detection and Management for the Space Station Freedom External Active Thermal Control System

1993-07-01
932149
This paper presents the integrated approach toward failure detection, isolation, and recovery/reconfiguration to be used for the Space Station Freedom External Active Thermal Control System (EATCS). The on-board and on-ground diagnostic capabilities of the EATCS are discussed. Time and safety critical failures, as well as noncritical failures, and the detection coverage for each provided by existing capabilities are reviewed. The allocation of responsibility between onboard software and ground-based systems, to be shown during ground testing at the Johnson Space Center, is described. Failure isolation capabilities allocated to the ground include some functionality originally found on orbit but moved to the ground to reduce on-board resource requirements. Complex failures requiring the analysis of multiple external variables, such as environmental conditions, heat loads, or station attitude, are also allocated to ground personnel.
Technical Paper

Integrated Aircraft Thermal Management and Power Generation

1993-07-01
932055
Future military aircraft will demand lower cost and lower weight subsystems that are more reliable, and easier to maintain and support. To identify and develop subsystems integration technologies that could provide benefits such as these to current and future military aircraft, the Air Force Wright Laboratory (WL/FIVE) initiated the Subsystem Integration Technology (SUIT) program in 1991. McDonnell Douglas Aerospace (MDA) together with Pratt and Whitney (PWA), and AlliedSignal Aerospace Systems and Equipment (ASE) was one of three teams that participated in Phase I of the SUIT program. The MDA Team's goal was to conceptually formulate a SUIT approach which would provide significantly reduced weight and costs while increasing cooling and power generation capabilities. These goals were achieved with a new and innovative energy subsystem suite which integrates aircraft and engine subsystem power, cooling, pumping, and controls.
Technical Paper

Initial Identification of Aircraft Tire Wear

1995-05-01
951394
Tactical aircraft have tire lives as low as 3-5 landings per tire causing excessive support costs. The goal of the Improved Tire Life (ITL) program was to begin developing technology to double aircraft tire life, particularly for tactical aircraft. ITL examined not only the tire, but also aircraft/landing gear design, aircraft operations, and the operational environment. ITL had three main thrusts which were successfully accomplished: 1) development of an analytical tire wear model, 2) initiation of technology development to increase tire life, and 3) exploration of new and unique testing methods for tire wear. This paper reports the work performed and the results of the USAF sponsored ITL program.
Technical Paper

Expert System Based Tool for Advanced Life Support System Optimization - A Mission Analysis Perspective

1993-07-01
932060
An expert system based Environmental Control and Life Support System (ECLSS) trade study tool is under development which calculates resource requirements and penalties for given system configurations and mission definition parameters. The user friendly, graphical software application allows important ECLSS resources such as power, mass, volume, resupply mass (consumable and expendable), heat rejection and ultimately cost to be analyzed in an efficient hierarchical manner. Hardware resources are calculated using scaling algorithms specific to each technology, based on existing hardware where possible. Fluid mass balances are tracked and summarized as fluids input into the system and waste output leaving the system. This tool will aid in technology selection and optimization of transportation vehicle or surface habitat designs.
Technical Paper

Enhanced Extra-Vehicular Activity Operations Through Custom Human Modeling Analysis

1997-07-01
972457
To sustain the extra-vehicular activity (EVA) rate required to assemble and maintain the International Space Station (ISS), we must enhance our ability to plan, train for, and execute EVAs. An underlying analysis capability must be in place to ensure EVA access to all external worksites either as a starting point for ground training, to generate information needed for on-orbit training, or to react quickly to develop contingency EVA plans, techniques, and procedures. This paper describes a potential flight experiment for application of custom human modeling analysis to plan and train for EVAs to enhance space station functionality and usability through assembly and operation.
Technical Paper

Effects of Flywheel Curvature on Aircraft Tire Footprint Behavior

1995-09-01
952020
Although aircraft tires are traditionally tested on external dynamometers, the effects of the curved test surface on normal contact pressure distribution and footprint area of a tire have not been previously addressed. Using the Tire Force Machine (TFM) at the Wright Laboratory Landing Gear Development Facility (LGDF), trends for pressure distribution and footprint area were investigated for concave, convex and flat plate surfaces. This evaluation was performed using the F-16 bias, F-16 radial and B-57 bias main landing gear tires at rated load and inflation pressures. The trends for overall tire footprint behavior indicate that the more convex the surface, the smaller the contact area and the larger the normal contact pressures. Conversely, the more concave the surface, the larger the contact area and the smaller the normal contact pressures. Based on these results, the study recommends a 168″ diameter concave (internal roadwheel) dynamometer for tire wear/durability tests.
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