Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “operational considerations”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 451 records · Page 25
All sourcesNASA NTRSDOE OSTI
NASA NTRS1984

Operational medicine in Space Station era

Medical considerations for long duration manned space missions are examined. The requirements and hardware for medical operations on the Space Station are diagrammatically presented. The physiological and psychological changes that have been observed during space flights are discussed. Crew health maintenance and medical care in the Space Station environment require earth-based and in flight continuity. It is also necessary to identify the appropriate zero-G therapeutic methods for treating a patient. Techniques for transferring patients in orbit and to earth are studied. Considerations are given to control and life support systems and data management for medical operations.

Furukawa, S.↗
NASA NTRS2002

Regaining Lost Separation in a Piloted Simulation of Autonomous Aircraft Operations

NASA is currently investigating a new concept of operations for the National Airspace System, designed to improve capacity while maintaining or improving current levels of safety. This concept, known as Distributed Air/Ground Traffic Management (DAG-TM), allows appropriately equipped autonomous aircraft to maneuver freely for flight optimization while resolving conflicts with other traffic and staying out of special use airspace and hazardous weather. While Airborne Separation Assurance System (ASAS) tools would normally allow pilots to resolve conflicts before they become hazardous, evaluation of system performance in sudden, near-term conflicts is needed in order to determine concept feasibility. If an acceptable safety level can be demonstrated in these situations, then operations may be conducted with lower separation minimums. An experiment was conducted in NASA Langley s Air Traffic Operations Lab to address issues associated with resolving near-term conflicts and the potential use of lower separation minimums. Sixteen commercial airline pilots flew a total of 32 traffic scenarios that required them to use prototype ASAS tools to resolve close range pop-up conflicts. Required separation standards were set at either 3 or 5 NM lateral spacing, with 1000 ft vertical separation being used for both cases. Reducing the lateral separation from 5 to 3 NM did not appear to increase operational risk, as indicated by the proximity to the intruder aircraft. Pilots performed better when they followed tactical guidance cues provided by ASAS than when they didn't follow the guidance. As air-air separation concepts are evolved, further studies will consider integration issues between ASAS and existing Airborne Collision Avoidance Systems (ACAS).These types of non-normal events will require the ASAS to provide effective alerts and resolutions prior to the time that an Airborne Collision Avoidance System (ACAS) would give a Resolution Advisory (RA). When an RA is issued, a pilot must take immediate action in order to avoid a potential near miss. The Traffic Alert and Collision Avoidance System (TCAS) II currently functions as an ACAS aboard commercial aircraft. Depending on the own aircraft s altitude, TCAS only issues RA s 15-35 seconds prior to the Closest Point of Approach (CPA). Prior to an RA, DAG-TM pilots operating autonomous aircraft must rely solely on ASAS for resolution guidance. An additional area of DAG-TM concept feasibility relates to a potential reduction in separation standards. Lower separation standards are likely needed in order to improve NAS efficiency and capacity. Current separation minimums are based in large part on the capabilities of older radar systems. Safety assessments are needed to determine the feasibility of reduced separation minimums. They will give strong consideration to surveillance system performance, including accuracy, integrity, and availability. Candidate surveillance systems include Automatic Dependent Surveillance-Broadcast (ADS-B) and multi-lateration systems. Considering studies done for Reduced Vertical Separation Minimums (RVSM) operations, it is likely that flight technical errors will also be considered. In addition to a thorough evaluation of surveillance system performance, a potential decision to lower the separation standards should also take operational considerations into account. An ASAS Safety Assessment study identified improper maneuvering in response to a conflict (due to ambiguous or improper resolution commands or a pilot s failure to comply with the resolution) as a potential safety risk. If near-term conflicts with lower separation minimums were determined to be more challenging for pilots, the severity of these risks could be even greater.

Barhydt, Richard↗
NASA NTRS1974

The Space Shuttle - Key considerations

Typical Space Shuttle flight operations, including launch/insertion, on-orbit operations, de-orbit, and ground turnaround, are summarized. The orbiter, main engine, and solid rocket boosters will be reusable. The Shuttle will be able to abort ascent and return the orbiter plus payload to the launch site if necessary. Mission capabilities include a 7-30 day duration, crew of 4-7 (with 1-4 payload specialists), and 14,500-29,500 kg payloads. Payload accommodations, including cabin, crew provisions, pointing and position stability, thermal constraints, electric power, communications, payload deployment and retrieval, contamination control, and kits for extended missions, are considered. The Thermal Protection System, utilizing pyrolized carbon and silica tiles, is described. The Space Shuttle Main Engine design and performance are considered and compared to those of the J-2 engine used on Saturn/Apollo missions.

Malkin, M. S.↗
NASA NTRS2018

Urban Air Mobility Airspace Integration Concepts and Considerations

Urban Air Mobility (UAM) - defined as safe and efficient air traffic operations in a metropolitan area for manned aircraft and unmanned aircraft systems - is being researched and developed by industry, academia, and government. Significant resources have been invested toward cultivating an ecosystem for Urban Air Mobility that includes manufacturers of electric vertical takeoff and landing aircraft, builders of takeoff and landing areas, and researchers of the airspace integration concepts, technologies, and procedures needed to conduct Urban Air Mobility operations safely and efficiently alongside other airspace users. This paper provides high-level descriptions of both emergent and early expanded operational concepts for Urban Air Mobility that NASA is developing. The scope of this work is defined in terms of missions, aircraft, airspace, and hazards. Past and current Urban Air Mobility operations are also reviewed, and the considerations for the data exchange architecture and communication, navigation, and surveillance requirements are also discussed. This paper will serve as a starting point to develop a framework for NASA's Urban Air Mobility airspace integration research and development efforts with partners and stakeholders that could include fast-time simulations, human-in-the-loop (HITL) simulations, and flight demonstrations.

airspace integration↗
NASA NTRS1982

Space Operations Center system analysis study extension. Volume 1: Executive summary

The analysis fo Space Operations Center (SOC) systems is summarized. Design considerations, configurations of the manned orbital space station, planned operational and research missions, and subsystem tradeoffs are considered. Integration into the space transportation system is discussed. A modular design concept permitting growth of the SOC as its functions are expanded is described. Additional considerations are special requirements for habitat modules, design modifications needed to operate in geosynchronous orbits, and use of the external tank for cryogenic propellant storage or as a pressurized hangar. A cost summary is presented.

Source record↗
NASA NTRS1976

High power operation of a 30-cm mercury bombardment ion thruster

The nominal input power of a 30-cm mercury bombardment ion thruster is 2.5 kW. A representative 30-cm thruster has been operated at higher power levels by increasing either the ion beam voltage or current. Initial results indicate that higher voltage (high specific impulse) operation requires only minor modifications in thruster design. Higher current (low specific impulse) operation, on the other hand, requires improvements in the capabilities of the discharge chamber and ion optics assembly designs to meet lifetime and/or performance specifications. Experimental data is presented and considerations for high power operation (up to 10 kW) are discussed.

Poeschel, R. L.↗
NASA NTRS1992

NLS propulsion design considerations

The new launch system is an evolutionary launch capability to meet the future national space launch need with significant improvements in operability and corresponding reduction in per flight costs. This improved capability is being achieved by: (1) providing the design, facilities, and infrastructure for cost effective operations; (2) developing a low cost, robust liquid hydrogen and liquid oxygen engine; and (3) using the capability and infrastructure of current tankage and shroud elements to derive a operationally efficient and highly reliable vehicle. The design and operational features of the propulsion system are key considerations in achieving the required reliability, operability and dependability. These design considerations will enable cost effective transportation to low earth orbit for a family of vehicles from 20 K to over 100 K lbs payload class.

Worlund, A. L.↗
NASA NTRS1986

MCC flight operations automation of STS orbiter systems monitoring

The integration of new capabilities into the Mission Control Center at the Johnson Space Center in Houston, Texas in order to improve the data monitoring and analysis of the STS is discussed. User interface application software and systems, such as the flight data file Shuttle mission simulator and failure analysis program, to be utilized for flight operations automation are examined. Consideration is given to task automation, the trend monitoring system, the data retrieval system, and the launch processing system. The development and functions of the Shuttle data analysis system, which is to operate in real time, are described.

Bates, William V., Jr.↗
NASA NTRS1980

Spacelab energetic ion mass spectrometer

Basic design criteria are given for an ion mass spectrometer for use in studying magnetospheric ion populations. The proposed instrument is composed of an electrostatic analyzer followed by a magnetic spectrometer and simultaneously measures the energy per unit and mass per unit charge of the ion species. An electromagnet is used for momentum analysis to extend the operational energy range over a much wider domain than is possible with the permanent magnets used in previous flights. The energetic ion source regions, ion energization mechanisms, field line tracing, coordinated investigations, and orbit considerations are discussed and operations of the momentum analyzer and of the electrostatic energy analyzer are examined.

Whalen, B. A.↗
NASA NTRS1979

The cost benefits of the Spacelab system to scientific investigations and space applications

Cost advantages of the Spacelab system to scientific experiments in space and space operations are presented. The payload integration concepts developed for Spacelab are examined, and it is shown that Spacelab and Shuttle integration, communications and data processing, launch support requirements and flight operations will provide a considerable savings in the costs of space research relative to previous space systems. Spacelab modular design, incorporating features such as standard payload interfaces, optional mission dependent equipment and standard services, such as the Experiment Computer Operating System, is shown to offer the user a wider range of services than previous programs, also at significantly lower costs. It is concluded that the Spacelab system will greatly reduce the costs and broaden the opportunities for scientific investigation in space.

Jean, O. C.↗
NASA NTRS1992

Concepts for a personnel launch system

Various personnel launch systems (PLS) that would serve as one element in a space transportation architecture (which might include heavy-lift cargo vehicles and multirole spacecraft such as the current Space Shuttle) are presented. The PLS might be developed and operated by NASA or it might be attained as a commercial service, completely developed and operated by private enterprise. Consideration is given to a biconic-shaped spacecraft configuration, designed to carry ten people and be reused many times, and intended to be an initial reference design to assist in the overall analysis of operations, maintenance and manufacturing for a PLS.

Petro, Andrew J.↗
NASA NTRSDate not supplied

Preliminary Development of Multi-Vehicle (m:N) Operations with NASA Langley’s Remote Vehicle Operations Center

To achieve the vision of Advanced Air Mobility (AAM), a transition from localized operations of aircraft to remote operations is being pursued across many use cases. This transition will allow fewer human operators to manage more increasingly autonomous aircraft (i.e., m operators managing N vehicles, or m:N). To study this operational concept, the National Aeronautics and Space Administration (NASA) Langley Research Center (LaRC) has developed a prototype remote vehicle operations center and ground control station (GCS) software to conduct research with simulated and real flight operations. To date, flight operations at LaRC have been limited to one vehicle per operator. However, the current paper describes initial development and considerations for enabling m:N flight operations at LaRC. Further, the research described in this paper provides the foundation for a concept of operations (ConOps) that will be developed to support remote operators managing multiple increasingly autonomous vehicles, with the goal of exploring human-autonomy teaming (HAT) concepts that enable more advanced m:N operations. Two key enablers have been identified to facilitate successful m:N operations: GCS software updates for multi-vehicle management and procedural updates for vehicle handoffs during off-nominal events. Additionally, specific modifications were identified across five key areas: technology and software, team structure, inter-team communication, contingency plans, and operator decision flows. Next steps in forming the LaRC m:N ConOps will include working with subject-matter experts to identify off-nominal scenarios, implementing the recommended GCS functionality for m:N operations, and performing integration testing of facility capabilities and new operational procedures. Although the future m:N ConOps will be tailored to the NASA LaRC remote operations facility and flight range, it is intended to be a transparent, accessible, and reality-based exemplar for external organizations seeking to create or evaluate their own m:N operational concepts.

m:N↗
NASA NTRSDate not supplied

Development of Urban Air Mobility (UAM) Vehicles for Ease of Operation

To date the air transportation system has been developed with the in-cremental introduction of new technology and with highly experienced air transport pilots and air traffic controllers overseeing flight operations. Thus, we currently have one of the safest commercial aviation systems in the world. General Aviation (GA) in the United States, however, has not always followed the same cautious and monitored approach to implementation; consequently, the GA safety record does not meet the high standards of commercial aviation. Recently, a new system known as Urban Air Mobility (UAM), is attracting considerable interest and investment from industry and government agencies. UAM refers to a system of passenger and small-cargo air transportation vehicles within an urban area with the goal of reducing the number of times we need to use our cars, thus improving urban traffic by moving people and cargo from crowded single pas-senger vehicles on our roads to personal and on-demand air vehicles. These UAM vehicles will be small and based on electric, Vertical-Take-Off-and-Landing (eV-TOL) systems. A significant component of UAM is offloading of flight-man-agement responsibilities from human pilots to newly-developed autonomy. Cur-rently, over 100 UAM vehicles are either in development or production. Most, if not all, have a goal of fully autonomous vehicle operations, but fully autonomous flying vehicles are not expected in the near future. Therefore, we are de-veloping concepts for UAM vehicles that will be easy to fly and/or manage by operators with minimal pilot training. In this paper we will discuss our human-automation teaming approach to develop an easy-to-operate VTOL aircraft, and some of the fly-by-wire technology needed to stabilize the vehicle so that a sim-ple ecological mental model of the flying task can be implemented. We will discuss the requirements for a stability augmentation system that must be developed to support our simple pilot input model, and also present design guidelines and requirements based on a pilot input and management model. Finally, our ap-proach to vehicle development will involve considerable operator testing and evaluation: improving pilot model, inceptors, displays and also work on a plan for how a UAM vehicle can be integrated with terminal area air traffic control airspace with minimal impact on controller workload.

UAM↗
NASA NTRS1983

Ejector nozzle test results at simulated flight conditions for an advanced supersonic transport propulsion system

Results are presented of wind tunnel tests conducted to verify the performance improvements of a refined ejector nozzle design for advanced supersonic transport propulsion systems. The analysis of results obtained at simulated engine operating conditions is emphasized. Tests were conducted with models of approximately 1/10th scale which were configured to simulate nozzle operation at takeoff, subsonic cruise, transonic cruise, and supersonic cruise. Transonic cruise operation was not a consideration during the nozzle design phase, although an evaluation at this condition was later conducted. Test results, characterized by thrust and flow coefficients, are given for a range of nozzle pressure ratios, emphasizing the thrust performance at the engine operating conditions predicted for each flight Mach number. The results indicate that nozzle performance goals were met or closely approximated at takeoff and supersonic cruise, while subsonic cruise performance was within 2.3 percent of the goal with further improvement possible.

Nelson, D. P.↗
NASA NTRS1993

Compatibility of information and mode of control: The case for natural control systems

The operation of control systems has been determined largely by mechanical constraints. Compatibility with the characteristics of the operator is a secondary consideration, with the result that control may never be optimal, control workload may interfere with performance of secondary tasks, and learning may be more difficult and protracted than necessary. With the introduction of a computer in the control loop, the mode of operation can be adapted to the operator, rather than vice versa. The concept of natural control is introduced to describe a system that supports control of the information used by the operator in achieving an intended goal. As an example, control of speed during simulated approach to a pad by helicopter pilots is used to contrast path-speed control with direct control of global optical flow-pattern information. Differences are evidenced in the performance domains of control activity, speed, and global optical flow velocity.

Owen, Dean H.↗
NASA NTRS1991

Utilizing expert systems for satellite monitoring and control

Spacecraft analysts in the spacecraft control center for the Cosmic Background Explorer (COBE) satellite are currently utilizing a fault-isolation expert system developed to assist in the isolation and correction of faults in the communications link. This system, the communication link expert assistance resource (CLEAR), monitors real time spacecraft and ground systems performance parameters in search of configuration discrepancies and communications link problems. If such a discrepancy or problem is isolated, CLEAR alerts the analyst and provides advice on how to resolve the problem swiftly and effectively. The CLEAR system is the first real time expert system to be used in the operational environment of a satellite control center at the NASA Goddard Space Flight Center. Clear has not only demonstrated the utility and potential of an expert system in the demanding environment of a satellite control center, but also has revealed many of the pitfalls and deficiencies of development of expert systems. One of the lessons learned from this and other initial expert system projects is that prototypes can often be developed quite rapidly, but operational expert systems require considerable effort. Development is generally a slow, tedious process that typically requires the special skills of trained programmers. Due to the success of CLEAR and several other systems in the control center domain, a large number of expert systems will certainly be developed to support control center operations during the early 1990's. To facilitate the development of these systems, a project was initiated to develop an integrated, domain-specific tool, the generic spacecraft analyst assistent (GenSAA), that alows the spacecraft analysts to rapidly create simple expert systems themselves. By providing a highly graphical point-and-select method of system development, GenSAA allows the analyst to utilize and/or modify previously developed rule bases and system components; thus, facilitating software reuse and reducing development time and effort.

Hughes, Peter M.↗
NASA NTRS2024

Effect of High-Speed Rotation on High-Temperature Superconducting Coils for High Efficiency Megawatt Motor

The use of a superconducting rotor in the High Efficiency Megawatt Motor (HEMM) comes with a number of challenges. The HEMM’s rotor must be designed so that the superconducting coil can tolerate the forces it will encounter during operation. These forces introduce considerable risk to the design of the HEMM. Because this risk cannot be adequately addressed through refined analysis, a set of experiments was deemed necessary to demonstrate that the HEMM’s superconducting coils can survive the stresses imparted by the centrifugal forces acting on the coil during full-speed operation of the machine. These experiments required spin testing a full-scale HEMM coil on a representative rotor structure at room temperature and sequentially higher rotation speeds and measuring the superconductivity response of the coil in liquid nitrogen (LN2) before and after each spin test. Tests were carried out to the full centripetal loading of a recent HEMM design. According to finite element analysis, this load produced stress components in the coil that exceed their design limit by a factor of 1 to 7.4. Although not yet confirmed, the current HEMM design is expected to produce even smaller stresses in the coil due to a 20 percent reduction in the coil’s mass and an increased volume of structural material. The only degradation of the coil that occurred during this testing resulted from a test rig failure and from the voltage taps, which are not part of the final coil design.

Electrified Aircraft Propulsion↗