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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 775 records · Page 43

All sources NASA NTRS DOE OSTI

NASA NTRS1985

Main propulsion system design recommendations for an advanced Orbit Transfer Vehicle

Various main propulsion system configurations of an advanced OTV are evaluated with respect to the probability of nonindependent failures, i.e., engine failures that disable the entire main propulsion system. Analysis of the life-cycle cost (LCC) indicates that LCC is sensitive to the main propulsion system reliability, vehicle dry weight, and propellant cost; it is relatively insensitive to the number of missions/overhaul, failures per mission, and EVA and IVA cost. In conclusion, two or three engines are recommended in view of their highest reliability, minimum life-cycle cost, and fail operational/fail safe capability.

Redd, L.↗

NASA NTRS1987

Service-Life Extension of Explosive Escape Devices

Chemical and functional tests yield conservative service-life estimates. Approach to extension of service lives of explosive devices in aircraft escape system developed, supported by testing of representative candidate devices to evaluate quantitatively effects of service, age, and degradation, and to enable responsible, conservative service-life determinations. Five types of explosive components evaluated: rigid and flexible explosive transfer lines; one-way transfers; flexible, linear-shaped charges; and initiation-handles. Extension of service in realistic manner provides both cost savings and increased system reliability.

Bement, L. J.↗

NASA NTRS1987

Advanced fuel cell concepts for future NASA missions

Studies of primary fuel cells for advanced all electric shuttle type vehicles show an all fuel cell power system with peak power capability of 100's of kW to be potentially lighter and have lower life cycle costs than a hybrid system using advanced H2O2 APU's for peak power and fuel cells for low power on orbit. Fuel cell specific weights of 1 to 3 lb/kW, a factor of 10 improvement over the orbiter power plant, are projected for the early 1990's. For satellite applications, a study to identify high performance regenerative hydrogen oxygen fuel cell concepts for geosynchronous orbit was completed. Emphasis was placed on concepts with the potential for high energy density (Wh/lb) and passive means for water and heat management to maximize system reliability. Both alkaline electrolyte and polymer membrane fuel cells were considered.

Stedman, J. K.↗

NASA NTRS1987

A new look at oxygen production on Mars - In situ propellant production (ISPP)

Consideration is given to the technique of producing oxygen on Mars from CO2 in the Martian atmosphere via in situ propellent production (ISPP). Mission implications of ISPP for both manned and unmanned Mars missions are described as well as ways to improve system reliability. Technology options that improve reliability and reduce power requirements include the use of adsorption pumps and advanced zirconia membranes. It is concluded that both manned and unmanned missions will benefit greatly from ISPP, especially in the context of a permanent manned base on Mars.

Frisbee, Robert H.↗

NASA NTRS1988

On the danger of redundancies in some aerospace mechanisms

An attempt is made to show that redundancies in some aerospace mechanisms do not generally improve the odds for success. Some of these redundancies may even be the very cause for failure of the system. To illustrate this fallacy, two designs based on the Control of Flexible Structures I (COFS I) Mast deployer and retractor assembly (DRA) are presented together with novel designs to circumvent such design inadequacies, while improving system reliability.

Chew, M.↗

NASA NTRS1988

Identification of high performance and component technology for space electrical power systems for use beyond the year 2000

Addressed are some of the space electrical power system technologies that should be developed for the U.S. space program to remain competitive in the 21st century. A brief historical overview of some U.S. manned/unmanned spacecraft power systems is discussed to establish the fact that electrical systems are and will continue to become more sophisticated as the power levels appoach those on the ground. Adaptive/Expert power systems that can function in an extraterrestrial environment will be required to take an appropriate action during electrical faults so that the impact is minimal. Manhours can be reduced significantly by relinquishing tedious routine system component maintenance to the adaptive/expert system. By cataloging component signatures over time this system can set a flag for a premature component failure and thus possibly avoid a major fault. High frequency operation is important if the electrical power system mass is to be cut significantly. High power semiconductor or vacuum switching components will be required to meet future power demands. System mass tradeoffs have been investigated in terms of operating at high temperature, efficiency, voltage regulation, and system reliability. High temperature semiconductors will be required. Silicon carbide materials will operate at a temperature around 1000 K and the diamond material up to 1300 K. The driver for elevated temperature operation is that radiator mass is reduced significantly because of inverse temperature to the fourth power.

Maisel, James E.↗

NASA NTRS1988

Sensor failure detection for jet engines

The use of analytical redundancy to improve gas turbine engine control system reliability through sensor failure detection, isolation, and accommodation is surveyed. Both the theoretical and application papers that form the technology base of turbine engine analytical redundancy research are discussed. Also, several important application efforts are reviewed. An assessment of the state-of-the-art in analytical redundancy technology is given.

Merrill, Walter C.↗

NASA NTRS1989

Non-contact temperature measurements in support of microgravity combustion experiments

Recent conceptual advances in the understanding of combustion science fundamentals in the context of microgravity processes and phenomenology have resulted in an increased demand for diagnostic systems of greater sophistication. Owing primarily to the severe operational constraints that accompany the space flight environment, measurement systems to date remain fairly primative in nature. Qualitative pictures provided by photographic recording media comprise the majority of the existing data, the remainder consisting of the output of conventional transducers, such as thermocouples, hot wires, and pressure transducers. The absence of the rather strong influence of buoyant convection renders microgravity combustion phenomena more fragile than their 1-G counterparts. The emphasis was placed on nonperturbing optical diagnostics. Other factors such as limited supplies of expendable reactants, and periods of microgravity time of sufficient duration, coupled with more fundamental questions regarding inherent length and time scales and reproducibility have favored multipoint or multidimensional techniques. While the development of optical diagnostics for application to combustion science is an extremely active area at present, the peculiarities of space flight hardware severely restrict the feasibility of implementing the majority of techniques which are being utilized in terrestrial applications. The additional requirements for system reliability and operational simplicity have tended to promote somewhat less commonly emphasized techniques such as refractive index mapping and molecular Rayleigh scattering, which are briefly discussed.

Greenberg, Paul S.↗

NASA NTRS1990

Computational methods for probability of instability calculations

This paper summarizes the development of the methods and a computer program to compute the probability of instability of a dynamic system than can be represented by a system of second-order ordinary linear differential equations. Two instability criteria based upon the roots of the characteristics equation or Routh-Hurwitz test functions are investigated. Computational methods based on system reliability analysis methods and importance sampling concepts are proposed to perform efficient probabilistic analysis. Numerical examples are provided to demonstrate the methods.

Wu, Y.-T.↗

NASA NTRS1990

A twenty-first century perspective

The status of the NASA assets which are operated by the Office of Space Operations is briefly reviewed. These assets include the ground network, the space network, and communications and data handling facilities. The current plans for each element are examined, and a projection of each is made to meet the user needs in the 21st century. The following factors are noted: increasingly responsive support will be required by the users; operational support concepts must be cost-effective to serve future missions; and a high degree of system reliability and availability will be required to support manned exploration and increasingly complex missions.

Aller, Robert O.↗

NASA NTRS1991

Heavy-lift launch vehicle propulsion considerations

Information on heavy-lift launch vehicle (HLLV) propulsion is given in viewgraph form. The objective was to investigate Earth to orbit options which minimize on-orbit operations and impacts to Space Station Freedom, have a reasonable capability to support Mars missions, and minimize mass in low Earth orbit. Potential synergism with the Space Transportation System is considered. Launch vehicle sizing results, HLLV thrust requirements, and propulsion system reliability are covered.

Ordway, Wayne L.↗

NASA NTRS1990

Application of automation and robotics to lunar surface human exploration operations

Major results of a study applying automation and robotics to lunar surface base buildup and operations concepts are reported. The study developed a reference base scenario with specific goals, equipment concepts, robot concepts, activity schedules and buildup manifests. It examined crew roles, contingency cases and system reliability, and proposed a set of technologies appropriate and necessary for effective lunar operations. This paper refers readers to four companion papers for quantitative details where appropriate.

Woodcock, Gordon R.↗

NASA NTRS1990

Sensor failure detection for jet engines

Merrill, Walter C.↗

NASA NTRS1991

The determination of operational and support requirements and costs during the conceptual design of space systems

The primary objective is to develop a methodology for predicting operational and support parameters and costs of proposed space systems. The first phase consists of: (1) the identification of data sources; (2) the development of a methodology for determining system reliability and maintainability parameters; (3) the implementation of the methodology through the use of prototypes; and (4) support in the development of an integrated computer model. The phase 1 results are documented and a direction is identified to proceed to accomplish the overall objective.

Ebeling, Charles↗

NASA NTRS1991

EMU evolution

Evolution of Extravehicular Mobility Unit (EMU) technology is necessary to support the Extravehicular Activity (EVA) requirements of the Space Station Freedom Program and those of the Space Exploration Initiative (SEI). Key qualities supporting long-duration missions include technologies that are highly reliable, durable, minimize logistics requirements, and are in-flight maintainable and serviceable. While these qualities are common to SSF and SEI EVA, development paths will differ where specific mission requirements impose different constraints. Development of reusable, regenerative technologies is necessary to minimize the logistics penalties. Increased battery discharge/recharge cycle life and usable wet life, compact high current density fuel cells, reusable CO2 absorbing media, and thermal radiation coupled with venting heat rejection technologies are just some methods of reducing consumables. Development must strive for durable, reliable systems that are in-flight serviceable and maintainable, which are vital for missions where logistics capabilities are extremely constrained. Key areas include suit components (e.g., gloves, boots, and cooling garments), and life support hardware such as fans, pumps, instrumentation, and emergency O2 systems. Higher pressure suits will reduce EVA prebreathe requirements and pre-EVA operations overall. Many challenges of higher pressure suits have been addressed by on-going development. Emphasis on glove development is necessary to provide low fatigue, dexterous glove mobility at higher suit pressures. Minimum impact hooks and scars which support an advanced SSF EMU have been identified. These accommodations permit upgrades that support servicing of low volume, high pressure oxygen systems, and hydrogen technologies such as fuel cell, and venting hydrogen heat rejection systems.

Rouen, M.↗

NASA NTRS1992

A combined Earth scanner and momentum wheel for attitude determination and control of small spacecraft

In order to satisfy the stringent cost and power requirements of small satellites, an advanced SCANWHEEL was designed, built, and qualified by ITHACO, Inc. The T-SCANWHEEL is a modular momentum/reaction wheel with an integral conical Earth scanner. The momentum wheel provides momentum bias and control torques about the pitch axis of a spacecraft. An angled scan mirror coupled to the rotating shaft of the momentum wheel provides a conical scan of the field-of-view of an infrared sensor to provide pitch-and-roll attitude information. By using the same motor and bearings for the momentum wheel and Earth scanner, the overall power consumption is reduced and the system reliability is enhanced. The evolution of the T-SCANWHEEL is presented, including design ground rules, tradeoff analyses, and performance results.

Bialke, Bill↗

NASA NTRS1992

An electromechanical actuation system for an expendable launch vehicle

A major effort at the NASA Lewis Research Center in recent years has been to develop electro-mechanical actuators (EMA's) to replace the hydraulic systems used for thrust vector control (TVC) on launch vehicles. This is an attempt ot overcome the inherent inefficiencies and costs associated with the existing hydraulic structures. General Dynamics Space Systems Division, under contract to NASA Lewis, is developing 18.6 kW (25 hp), 29.8 kW (40 hp), and 52.2 kW (70 hp) peak EMA systems to meet the power demands for TVC on a family of vehicles developed for the National Launch System. These systems utilize a pulse population modulated converter and field-oriented control scheme to obtain independent control of both the voltage and frequency. These techniques allow an induction motor to be operated at its maximum torque at all times. At NASA Lewis, we are building on this technology to develop our own in-house system capable of meeting the peak power requirements for an expendable launch vehicle (ELV) such as the Atlas. Our EMA will be capable of delivering 22.4 kW (30 hp) peak power with a nominal of 6.0 kW (8 hp). This system differs from the previous ones in two areas: (1) the use of advanced control methods, and (2) the incorporation of built-in-test. The advanced controls are essential for minimizing the controller size, while the built-in-test is necessary to enhance the system reliability and vehicle health monitoring. The ultimate goal of this program is to demonstrate an EMA which will be capable of self-test and easy integration into other projects. This paper will describe the effort underway at NASA Lewis to develop an EMA for an Atlas class ELV. An explanation will be given for each major technology block, and the status of each major technology block and the status of the overall program will be reported.

Burrows, Linda M.↗

NASA NTRS1992

The ACTS Spacecraft

The tested physical and performance characteristics of the ACTS spacecraft are presented with emphasis placed on those for the multibeam antenna, the communications electronics panel, and the bus. Performance measurements for the multibeam antenna agree with predicted parameters, and the electronics panel provides four transponder channels for redundancy and system reliability. The spacecraft bus provides unique features including an attitude-control subsystem with autotrack for pitch accuracy, a sun sensor for yaw control, and thruster firing for dual spin turns.

Gargione, Frank↗