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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 1,297 records · Page 72

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NASA NTRS1996

An Overview on Aerospatiale Magnetic Bearing Products for Spacecraft Attitude Control and for Industry

Aerospatiale magnetic bearings are based on the use of permanent magnets and on the control of the rotor around a zero force equilibrium point. The present developments of magnetic bearing wheels for space applications focus on the versatility of a basic design which leads to a family of reaction and momentum wheels with tailored torque and kinetic momentum, leading to competitive mass and cost. The present industrial applications concern kinetic energy accumulators, medical x-ray rotating devices, avionics equipment, cryotechnic compressors and vacuum pumps.

Samuel, Alain↗

NASA NTRS1996

Experimental Investigation of Pool Boiling Heat Transfer Enhancement in Microgravity in the Presence of Electric Fields

Boiling is an effective mode of heat transfer since high heat flux levels are possible driven by relatively small temperature differences. The high heat transfer coefficients associated with boiling have made the use of these processes increasingly attractive to aerospace engineering. Applications of this type include compact evaporators in the thermal control of aircraft avionics and spacecraft environments, heat pipes, and use of boiling to cool electronic equipment. In spite of its efficiency, cooling based on liquid-vapor phase change processes has not yet found wide application in aerospace engineering due to specific problems associated with the low gravity environment. After a heated surface has reached the superheat required for the initiation of nucleate boiling, bubbles will start forming at nucleation sites along the solid interface by evaporation of the liquid. Bubbles in contact with the wall will continue growing by this mechanism until they detach. In terrestrial conditions, bubble detachment is determined by the competition between body forces (e.g. buoyancy) and surface tension forces that act to anchor the bubble along the three phase contact line. For a given body force potential and a balance of tensions along the three phase contact line, bubbles must reach a critical size before the body force can cause them to detach from the wall. In a low gravity environment the critical bubble size for detachment is much larger than under terrestrial conditions, since buoyancy is a less effective means of bubble removal. Active techniques of heat transfer enhancement in single phase and phase change processes by utilizing electric fields have been the subject of intensive research during recent years. The field of electrohydrodynamics (EHD) deals with the interactions between electric fields, flow fields and temperature fields. Previous studies indicate that in terrestrial applications nucleate boiling heat transfer can be increased by a factor of 50 as compared to values obtained for the same system without electric fields. Imposing an external electric field holds the promise to improve pool boiling heat transfer in low gravity, since a phase separation force other than gravity is introduced. The goal of our research is to experimentally investigate the potential of EHD and the mechanisms responsible for EHD heat transfer enhancement in boiling in low gravity conditions.

Herman, Cila↗

NASA NTRS1995

Deployer Performance Results for the TSS-1 Mission

Performance of the Tethered Satellite System (TSS) Deployer during the STS-46 mission (July and August 1992) is analyzed in terms of hardware operation at the component and system level. Although only a limited deployment of the satellite was achieved (256 meters vs 20 kilometers planned), the mission served to verify the basic capability of the Deployer to release, control and retrieve a tethered satellite. - Deployer operational flexibility that was demonstrated during the flight is also addressed. Martin Marietta was the prime contractor for the development of the Deployer, under management of the NASA George C. Marshall Space Flight Center (MSFC). The satellite was provided by Alenia, Torino, Italy under contract to the Agencia Spaziale Italiana (ASI). Proper operation of the avionics components and the majority of mechanisms was observed during the flight. System operations driven by control laws for the deployment and retrieval of the satellite were also successful for the limited deployment distance. Anomalies included separation problems for one of the two umbilical connectors between the Deployer and satellite, tether jamming (at initial Satellite fly-away and at a deployment distance of 224 meters), and a mechanical interference which prevented tether deployment beyond 256 meters. The Deployer was used in several off-nominal conditions to respond to these anomalies, which ultimately enabled a successful satellite retrieval and preservation of hardware integrity for a future re-flight. The paper begins with an introduction defining the significance of the TSS-1 mission. The body of the paper is divided into four major sections: (1) Description of Deployer System and Components, (2) Deployer Components/Systems Demonstrating Successful Operation, (3) Hardware Anomalies and Operational Responses, and (4) Design Modifications for the TSS-1R Re-flight Mission. Conclusions from the TSS-1 mission, including lessons learned are presented at the end of the manuscript.

Marshall, Leland S.↗

NASA NTRS1996

F-15B/Flight Test Fixture 2: A Test Bed for Flight Research

NASA Dryden Flight Research Center has developed a second-generation flight test fixture for use as a generic test bed for aerodynamic and fluid mechanics research. The Flight Test Fixture 2 (FTF-2) is a low-aspect-ratio vertical fin-like shape that is mounted on the centerline of the F-I5B lower fuselage. The fixture is designed for flight research at Mach numbers to a maximum of 2.0. The FTF-2 is a composite structure with a modular configuration and removable components for functional flexibility. This report documents the flow environment of the fixture, such as surface pressure distributions and boundary-layer profiles, throughout a matrix of conditions within the F-15B/FTF-2 flight envelope. Environmental conditions within the fixture are presented to assist in the design and testing of future avionics and instrumentation. The intent of this document is to serve as a user's guide and assist in the development of future flight experiments that use the FTF-2 as a test bed. Additional information enclosed in the appendices has been included to assist with more detailed analyses, if required.

David M Richwine↗

NASA NTRS1997

Designing for Maintainability and System Availability

The final goal for a delivered system (whether a car, aircraft, avionics box or computer) should be its availability to operate and perform its intended function over its expected design life. Hence, in designing a system, we cannot think in terms of delivering the system and just walking away. The system supplier needs to provide support throughout the operating life of the product. Here, supportability requires an effective combination of reliability, maintainability, logistics and operations engineering (as well as safety engineering) to have a system that is available for its intended use throughout its designated mission lifetime. Maintainability is a key driving element in the effective support and upkeep of the system as well as providing the ability to modify and upgrade the system throughout its lifetime. This paper then, will concentrate on maintainability and its integration into the system engineering and design process. The topics to be covered include elements of maintainability, the total cost of ownership, how system availability, maintenance and logistics costs and spare parts cost effect the overall program costs. System analysis and maintainability will show how maintainability fits into the overall systems approach to project development. Maintainability processes and documents will focus on how maintainability is to be performed and what documents are typically generated for a large scale program. Maintainability analysis shows how trade-offs can be performed for various alternative components. The conclusions summarize the paper and are followed by specific problems for hands-on training.

Lalli, Vincent R.↗

NASA NTRS1997

Micro-Optic Color Separation Technology for Efficient Projection Displays

Phase 1 of this project focused on development of an overall optical concept which incorporated a single liquid crystal spatial light modulator. The system achieved full color by utilizing an echelon grating, which diffracted the incident light into three orders with different color spectra, in combination with a microlens array, which spatially separated RGB bands and directed the light of the appropriate wavelength to the appropriate color dot. Preliminary echelon grating designs were provided by MIT/LL and reviewed by Rockwell. Additional Rockwell activities included the Identification of microlens designs, light sources (ILC), and projection optics to fulfill the overall design requirements. An Internal subcontract was established with Rockwell's Collins Avionics and Communications Division (CACD) which specified the liquid crystal SLM (Sharp Model No. LQ 46EO2) and built the projection display baseline projector. Full Color projected video images were produced and shown at the 1995 HDS meeting in Washington. Analysis of the luminance performance of the projector and detailed parameter trade studies helped define the dependence of overall display efficiency on lamp collimation, and indicated that a lamp with very small arc dimension is required for the optical concept to be viable.

Gunning, W. J.↗

NASA NTRS1984

Report of the Panel on Guidance, Navigation, and Control

Guidance, navigation, and control (GNC) systems have historically been vital to improving operational capability of aircraft. The development of autopilots and electronic navigation systems has greatly aided the crew in flying precise routes in all weather conditions while at the same time reducing pilot workload. Advances in high-integrity onboard computing and electronics technology have resulted in a significant increase in the capability of these subsystems to perform more reliably, efficiently, and safely. Onboard computing and control system capability has provided new design approaches for the aircraft designer. By using automatic control systems to stabilize the aircraft, the designer can relax certain conventional aerodynamic stability requirements and achieve aircraft performance benefits. Thus, modern fighter aircraft are designed with low levels, or in fact, negative levels of longitudinal static stability to boost maneuvering capability and cruise performance, relying on the use of full-time, full-authority automatic stability augmentation systems to stabilize the aircraft. During the next 20 years, GNC systems will become a driving force in aircraft design. Instead of making separately designed major aircraft systems work together, the designer will exploit the interaction and integration of aerodynamic, structural, and propulsion system controls to provide a better aircraft. The benefits of such integrated designs have been demonstrated already. Integrated digital control of the engine inlet and autopilot systems on a NASA YF-12 research aircraft resulted in a range increase of 7 percent. A civil transport derivative using extensions on each wing and an active control system to minimize the requirement for structural modifications achieved significant cruise performance improvements. These are first-generation applications of advanced GNC systems. More significant benefits are achievable by the year 2000. Complete integration of aerodynamic, propulsion and structural controls, and mission avionics will provide dramatically better aircraft performance, new capability (low observability, supermaneuverability) and/or improved mission effectiveness. This requires a concurrent, multidisciplinary design approach early in the design stage. The role of advanced GNC systems in future aircraft is not an option.

Fraser, Donald C.↗

NASA NTRS1997

Head Up Displays. (Latest Citations from the Aerospace Database)

The bibliography contains citations concerning the design, fabrication, and applications of head up displays (HUDs). Applications include military aircraft, helicopters, space shuttle, and commercial aircraft. Functions of the display include instrument approach, target tracking, and navigation. The head up display provides for an integrated avionics system with the pilot in the loop. (Contains 50-250 citations and includes a subject term index and title list.)

BIBLIOGRAPHIES↗

NASA NTRS1996

Computer Architecture. (Latest Citations from the Aerospace Database)

The bibliography contains citations concerning research and development in the field of computer architecture. Design of computer systems, microcomputer components, and digital networks are among the topics discussed. Multimicroprocessor system performance, software development, and aerospace avionics applications are also included. (Contains 50-250 citations and includes a subject term index and title list.)

BIBLIOGRAPHIES↗

NASA NTRS1996

Thick Films: Electronic Applications. (Latest citations from the Aerospace Database)

The bibliography contains citations concerning the design, development, fabrication, and evaluation of thick film electronic devices. Thick film solar cells, thick films for radiation conduction, deposition processes, conductive inks are among the topics discussed. Applications in military and civilian avionics are examined.

BIBLIOGRAPHIES↗

NASA NTRS1996

Head Up Displays. (Latest citations from the Aerospace Database)

DISPLAY DEVICES↗

NASA NTRS1998

Aiding Vertical Guidance Understanding

A two-part study was conducted to evaluate modern flight deck automation and interfaces. In the first part, a survey was performed to validate the existence of automation surprises with current pilots. Results indicated that pilots were often surprised by the behavior of the automation. There were several surprises that were reported more frequently than others. An experimental study was then performed to evaluate (1) the reduction of automation surprises through training specifically for the vertical guidance logic, and (2) a new display that describes the flight guidance in terms of aircraft behaviors instead of control modes. The study was performed in a simulator that was used to run a complete flight with actual airline pilots. Three groups were used to evaluate the guidance display and training. In the training, condition, participants went through a training program for vertical guidance before flying the simulation. In the display condition, participants ran through the same training program and then flew the experimental scenario with the new Guidance-Flight Mode Annunciator (G-FMA). Results showed improved pilot performance when given training specifically for the vertical guidance logic and greater improvements when given the training and the new G-FMA. Using actual behavior of the avionics to design pilot training and FMA is feasible, and when the automated vertical guidance mode of the Flight Management System is engaged, the display of the guidance mode and targets yields improved pilot performance.

Feary, Michael↗

NASA NTRS1997

Temporal, Spatial, and Diurnal Patterns in Avian Activity at the Shuttle Landing Facility, John F. Kennedy Space Center, Florida, USA

Spatial and temporal patterns in bird abundance within the five-mile airspace at the Shuttle Landing Facility (SLF) on John F. Kennedy Space Center (KSC), Florida, USA were investigated for purposes of quantifying Bird Aircraft Strike Hazards (BASH). The airspace is surrounded by the Merritt Island National Wildlife Refuge (MINWR) which provides habitat for approximately 331 resident and migratory bird species. Potential bird strike hazards were greatest around sunrise and sunset for most avian taxonomic groups, including wading birds, most raptors, pelicans, gulls/terns, shorebirds, and passerines. Turkey Vultures and Black Vultures were identified as a primary threat to aircraft operations and were represented in 33% of the samples. Diurnal vulture activity varied seasonally with the development of air thermals in the airspace surrounding the SLF. Variation in the presence and abundance of migratory species was shown for American Robins, swallows, and several species of shorebirds. Analyses of bird activities provides for planning of avionics operations during periods of low-dsk and allows for risk minimization measures during periods of high-risk.

Larson, Vickie L.↗

NASA NTRS1998

Framework for Small-Scale Experiments in Software Engineering: Guidance and Control Software Project: Software Engineering Case Study

Software is becoming increasingly significant in today's critical avionics systems. To achieve safe, reliable software, government regulatory agencies such as the Federal Aviation Administration (FAA) and the Department of Defense mandate the use of certain software development methods. However, little scientific evidence exists to show a correlation between software development methods and product quality. Given this lack of evidence, a series of experiments has been conducted to understand why and how software fails. The Guidance and Control Software (GCS) project is the latest in this series. The GCS project is a case study of the Requirements and Technical Concepts for Aviation RTCA/DO-178B guidelines, Software Considerations in Airborne Systems and Equipment Certification. All civil transport airframe and equipment vendors are expected to comply with these guidelines in building systems to be certified by the FAA for use in commercial aircraft. For the case study, two implementations of a guidance and control application were developed to comply with the DO-178B guidelines for Level A (critical) software. The development included the requirements, design, coding, verification, configuration management, and quality assurance processes. This paper discusses the details of the GCS project and presents the results of the case study.

Hayhurst, Kelly J.↗

NASA NTRS1998

Reflight of the First Microgravity Science Laboratory: Quick Turnaround of a Space Shuttle Mission

Due to the short flight of Space Shuttle Columbia, STS-83, in April 1997, NASA chose to refly the same crew, shuttle, and payload on STS-94 in July 1997. This was the first reflight of an entire mission complement. The reflight of the First Microgravity Science Laboratory (MSL-1) on STS-94 required an innovative approach to Space Shuttle payload ground processing. Ground processing time for the Spacelab Module, which served as the laboratory for MSL-1 experiments, was reduced by seventy-five percent. The Spacelab Module is a pressurized facility with avionics and thermal cooling and heating accommodations. Boeing-Huntsville, formerly McDonnell Douglas Aerospace, has been the Spacelab Integration Contractor since 1977. The first Spacelab Module flight was in 1983. An experienced team determined what was required to refurbish the Spacelab Module for reflight. Team members had diverse knowledge, skills, and background. An engineering assessment of subsystems, including mechanical, electrical power distribution, command and data management, and environmental control and life support, was performed. Recommendations for resolution of STS-83 Spacelab in-flight anomalies were provided. Inspections and tests that must be done on critical Spacelab components were identified. This assessment contributed to the successful reflight of MSL-1, the fifteenth Spacelab Module mission.

Simms, Yvonne↗

NASA NTRS1998

Flight Guidance System Validation Using SPIN

To verify the requirements for the mode control logic of a Flight Guidance System (FGS) we applied SPIN, a widely used software package that supports the formal verification of distributed systems. These requirements, collectively called the FGS specification, were developed at Rockwell Avionics & Communications and expressed in terms of the Consortium Requirements Engineering (CoRE) method. The properties to be verified are the invariants formulated in the FGS specification, along with the standard properties of consistency and completeness. The project had two stages. First, the FGS specification and the properties to be verified were reformulated in PROMELA, the input language of SPIN. This involved a semantics issue, as some constructs of the FGS specification do not have well-defined semantics in CoRE. Then we attempted to verify the requirements' properties using the automatic model checking facilities of SPIN. Due to the large size of the state space of the FGS specification an exhaustive state space analysis with SPIN turned out to be impossible. So we used the supertrace model checking procedure of SPIN that provides for a partial analysis of the state space. During this process, we found some subtle errors in the FGS specification.

Naydich, Dimitri↗

NASA NTRS1998

FAA/NASA Joint University Program for Air Transportation Research 1994-1995

The Joint University Program for Air Transportation Research (JUP) is a coordinated set of three grants co-sponsored by the Federal Aviation Administration (FAA) and the National Aeronautics and Space Administration (NASA). Under JUP, three institutions: the Massachusetts Institute of Technology, Princeton, and Ohio Universities receive research grants and collaborate with FAA and NASA in defining and performing civil aeronautics research in a multitude of areas. Some of these disciplines are artificial intelligence, control theory, atmospheric hazards, navigation, avionics, human factors, flight dynamics, air traffic management, and electronic communications.

NASA PROGRAMS↗

NASA NTRS1975

Analysis of the Flight Motions of a Small Deployable Glider Configuration

An investigation was conducted at the request of the U.S. Air Force Avionics Laboratory to analyze the flight characteristics of a small uncontrolled glider with folding wings. The study consisted of wind-tunnel tests of an actual glider and a theoretical analysis of the performance, stability, and trimmability of the configuration.

Coe, Paul L., Jr.↗