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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 109 records · Page 6

Configuration considerations in the design of earth-to-orbit transports

The various configuration options for earth-to-orbit transports are discussed with specific attention given to: ballistic vs. winged vehicles; horizontal takeoff vs. vertical takeoff; two stage vs. single stage; rocket propulsion system options; structure and thermal protection systems options; and weight growth vs. size. It is suggested that the single-stage system has many attractive features such as the elimination of booster-to-orbiter mating problems and the elimination of the need for the development of a cruise system. From the standpoint of weight reduction, it appears desirable to combine as many functions as possible in the outer shell of the transport system.

Macconochie, I. O.↗

System-of-Systems Considerations in the Notional Development of a Metropolitan Aerial Transportation System

There are substantial future challenges related to sustaining and improving efficient, cost-effective, and environmentally friendly transportation options for urban regions. Over the past several decades there has been a worldwide trend towards increasing urbanization of society. Accompanying this urbanization are increasing surface transportation infrastructure costs and, despite public infrastructure investments, increasing surface transportation "gridlock." In addition to this global urbanization trend, there has been a substantial increase in concern regarding energy sustainability, fossil fuel emissions, and the potential implications of global climate change. A recently completed study investigated the feasibility of an aviation solution for future urban transportation (refs. 1, 2). Such an aerial transportation system could ideally address some of the above noted concerns related to urbanization, transportation gridlock, and fossil fuel emissions (ref. 3). A metro/regional aerial transportation system could also provide enhanced transportation flexibility to accommodate extraordinary events such as surface (rail/road) transportation network disruptions and emergency/disaster relief responses.

Alonso, Juan J.↗

Development and application of ride-quality criteria

A program for the development of ride-quality vibration criteria applicable to the design and evaluation of air and surface transportation systems is described. Consideration is given to the magnitude of vehicle vibration experienced by the passenger, the frequency of vibration, the direction of vibration, and the influence of seat dynamics on passenger response. Comparative vibration measurements are presented for a variety of air and surface transportation systems. In addition, simulator data on seat dynamics and passenger response are presented. Results suggest the relative merits of various physical descriptors and measurement locations for characterizing the vibration in terms suitable for the design and/or evaluation of transportation systems.

Stephens, D. G.↗

A Robust Scalable Transportation System Concept

This report documents the 2005 Revolutionary System Concept for Aeronautics (RSCA) study entitled "A Robust, Scalable Transportation System Concept". The objective of the study was to generate, at a high-level of abstraction, characteristics of a new concept for the National Airspace System, or the new NAS, under which transportation goals such as increased throughput, delay reduction, and improved robustness could be realized. Since such an objective can be overwhelmingly complex if pursued at the lowest levels of detail, instead a System-of-Systems (SoS) approach was adopted to model alternative air transportation architectures at a high level. The SoS approach allows the consideration of not only the technical aspects of the NAS", but also incorporates policy, socio-economic, and alternative transportation system considerations into one architecture. While the representations of the individual systems are basic, the higher level approach allows for ways to optimize the SoS at the network level, determining the best topology (i.e. configuration of nodes and links). The final product (concept) is a set of rules of behavior and network structure that not only satisfies national transportation goals, but represents the high impact rules that accomplish those goals by getting the agents to "do the right thing" naturally. The novel combination of Agent Based Modeling and Network Theory provides the core analysis methodology in the System-of-Systems approach. Our method of approach is non-deterministic which means, fundamentally, it asks and answers different questions than deterministic models. The nondeterministic method is necessary primarily due to our marriage of human systems with technological ones in a partially unknown set of future worlds. Our goal is to understand and simulate how the SoS, human and technological components combined, evolve.

Hahn, Andrew↗

Advanced space program studies: Overall executive summary

Studies were conducted to provide NASA with advanced planning analyses which relate integrated space program goals and options to credible technical capabilities, applications potential, and funding resources. The studies concentrated on the following subjects: (1) upper stage options for the space transportation system based on payload considerations, (2) space servicing and standardization of payloads, (3) payload operations, and (4) space transportation system economic analyses related to user charges and new space applications. A systems cost/performance model was developed to synthesize automated, unmanned spacecraft configurations based on the system requirements and a list of equipments at the assembly level.

Sitney, L. R.↗

Manned transportation system study - Evaluation of candidate transportation architectures

The overall evaluation process, the tool developed to perform the evaluation, and the evaluation results in determining the right approach to meet the nation's mannned transportation needs are presented. To address the various considerations, architecture sets consisting of the candidate transportation systems are constructed. As this methodology results in multiple architectures to examine, an architecture evaluation tool was developed to facilitate the evaluation of the architecture attribute values from the system values of the attributes.

Lance, Nicholas↗

Distribution of surface extremes in the United States

Extreme design environment data are presented for consideration in aerospace vehicle transportation, fabrication, or testing. Values were obtained by using data from weather stations and published meteorological articles. Maps depict snow fall, hail distribution, atmospheric pressure, atmospheric temperature, and surface elevations.

Daniels, G. E.↗

Considerations in the design of tip-coupled air-transport systems

It is shown that the lift-drag ratio of tip-coupled systems can be expressed as a simple multiple of the lift-drag ratio of the isolated units comprising the system. When operated for maximum lift-drag ratio, the extent of the coupled system is limited by maximum lift coefficient, high-altitude engine characteristics, and degraded performance of the isolated unit climbing to couple into the system. When operated at constant altitude, the gain from coupling is severely limited. If the cruise altitude is that for best performance of the isolated unit, the system lift-drag ratio can be no better than twice that of the isolated unit even when an infinite number of units are coupled. System performance may be further degraded since span-load distributions which yield good performance for the individual units reduce the efficiency of the coupled system. Coupling a pair of modern transport aircraft results in only about half the expected gain because of a poor span-distribution across the coupled pair. The control deflections required to maintain roll and pitch equilibrium further degrade the possible gain.

Heyson, H. H.↗

Considerations in STS payload environmental verification

Considerations regarding the Space Transportation System (STS) payload environmental verification are reviewed. It is noted that emphasis is placed on testing at the subassembly level and that the basic objective of structural dynamic payload verification is to ensure reliability in a cost-effective manner. Structural analyses consist of: (1) stress analysis for critical loading conditions, (2) model analysis for launch and orbital configurations, (3) flight loads analysis, (4) test simulation analysis to verify models, (5) kinematic analysis of deployment/retraction sequences, and (6) structural-thermal-optical program analysis. In addition to these approaches, payload verification programs are being developed in the thermal-vacuum area. These include the exposure to extreme temperatures, temperature cycling, thermal-balance testing and thermal-vacuum testing.

Keegan, W. B.↗

Spatially Characterizing Effective Timber Supply

The structure of a computer-oriented cartographic model for assessing roundwood supply for generation of base load electricity is discussed. The model provides an analytical procedure for coupling spatial information of harvesting economics and owner willingness to sell stumpages. Supply is characterized in terms of standing timber; of accessibility considering various harvesting and hauling factors; and of availability as affected by ownership and residential patterns. Factors governing accessibility to timber include effective harvesting distance to haulic roads as modified by barriers and slopes. Haul distance is expressed in units that take into account the relative ease of travel along various road types to a central processing facility. Areas of accessible timber are grouped into spatial units, termed 'timbersheds', of common access to particular haul road segments that belong to unique 'transport zones'. Timber availability considerations include size of ownership parcels, housing density and excluded areas. The analysis techniques are demonstrated for a cartographic data base in western Massachusetts.

Berry, J. K.↗

Martian rampart crater ejecta - Experiments and analysis of melt-water interaction

The possible effects of explosive water vaporization on ejecta emplacement after impact into a wet target are described. A general model is formulated from analysis of Viking imagery of Mars and experimental vapor explosions as well as consideration of fluidized particulate transport and lobate volcanic deposits. The discussed model contends that as target water content increases, the effects of vapor expansion due to impact increasingly modify the ballistic flow field during crater excavation. This modification results in transport by gravity-driven surface flowage, and is similar to that of atmospheric drag effects on ejecta modelled by Schultz and Gault (1979).

Wohletz, K. H.↗

A Space Station tethered orbital refueling facility

A planned function of the Space Station is to refurbish and refuel an advanced space-based LO2/LH2 orbit transfer vehicle. An alternative to propellant storage at the station is to use a remote facility tied to the station with a long tether. Preliminary design of such a facility is described with emphasis on fluid transfer and storage requirements. Using tether lengths of at least 300 ft, gravity gradient forces will dominate surface tension in such a system. Although gravity driven transfer is difficult because of line pressure drops, fluid settling over the tank outlet greatly alleviates acquisition concerns and will facilitate vented tank fills. The major concern with a tethered orbital refueling facility is its considerable operational complexity including transport of the OTV to and from the facility.

Fester, D. A.↗

Tethered orbital propellant depot

A planned function of the Space Station is to refurbish and refuel an advanced space-based LO2/LH2 orbit transfer vehicle. An alternative to propellant storage at the station is to use a remote facility tied to the station with a log tether. Preliminary design of such a facility is described with emphasis on fluid transfer and storage requirements. Using tether lengths of at least 300 ft, gravity gradient forces will dominate surface tension in such a system. Although gravity given transfer is difficult because of line pressure drops, fluid settling over the tank outlet greatly alleviates acquisition concerns and will facilitate vented tank fills. The major concern with a tethered orbital refueling facility is its considerable operational complexity including transport of the OTV to and from the facility.

Fester, D. A.↗

Mars exploration program

An overview of the Mars Exploration Program is presented in outline and graphic form. Mission objectives, mission strategy, operations concept, transportation element, launch vehicle considerations and program schedule are addressed.

Weary, Dwayne↗

The interplanetary superhighway and human habitation on the Moon

NASA's new vision to return humans to the Moon is the next practical step in expanding human habitation beyond Earth. As the Habitation 2006 Conference website states: 'new knowledge and new technologies are required.' Along with the development of new habitation systems, an important consideration is how to transport these heavy structures cheaply to the Moon? We propose the use of ultra-low-energy orbits in the Interplanetary Superhighway as an economical and effective means to deliver cargo to the Moon. This approach not only reduces the propulsion cost, but also provides enormous flexibility and robustness to the mission architecture.

Jupiter Icy Moons Orbiter (JIMO)↗

Variability of Irreversible Poleward Transport in the Lower Stratosphere

The ascent and descent of the Brewer-Dobson circulation plays a large role in determining the distributions of many constituents in the extratropical lower stratosphere. However, relatively fast, quasi-horizontal transport out of the tropics and polar regions also significantly contribute to determining these distributions. The tropical tape recorder signal assures that there must be outflow from the tropics into the extratropical lower stratosphere. The phase of the quasi-biennial oscillation (QBO) and state of the polar vortex are known to modulate the transport from the tropical and polar regions, respectively. In this study we examine multiple years of ozone distributions in the extratropical lower stratosphere observed by the Aura Microwave Limb Sounder (MLS) and the Aura High Resolution Dynamic Limb Sounder (HIRDLS). The distributions are compared with analyses of irreversible, meridional isentropic transport. We show that there is considerable year-to-year seasonal variability in the amount of irreversible transport from the tropics, which is related to both the phase of the QBO and the state of the polar vortex. The reversibility of the transport is consistent with the number of observed breaking waves. The variability of the atmospheric index of refraction in the lower stratosphere is shown to be significantly correlated with the wave breaking and amount of irreversible transport. Finally, we will show that the seasonal extratropical stratosphere to troposphere transport of ozone can be substantially modulated by the amount of irreversible meridional transport in the lower stratosphere and we investigate how observable these differences are in data of tropospheric ozone.

Olsen, Mark↗

Updates on Modeling the Water Cycle with the NASA Ames Mars Global Climate Model

Global Circulation Models (GCMs) have made steady progress in simulating the current Mars water cycle. It is now widely recognized that clouds are a critical component that can significantly affect the nature of the simulated water cycle. Two processes in particular are key to implementing clouds in a GCM: the microphysical processes of formation and dissipation, and their radiative effects on heating/ cooling rates. Together, these processes alter the thermal structure, change the dynamics, and regulate inter-hemispheric transport. We have made considerable progress representing these processes in the NASA Ames GCM, particularly in the presence of radiatively active water ice clouds. We present the current state of our group's water cycle modeling efforts, show results from selected simulations, highlight some of the issues, and discuss avenues for further investigation.­

Global Circulation Models (GCMs)↗

Marquardt's Mach 4.5 Supercharged Ejector Ramjet (SERJ) High-Performance Aircraft Engine Project: Unfulfilled Aspirations Ca.1970

The Supercharged Ejector Ramjet (SERJ) engine developments of the 1960s, as pursued by The Marquardt Corporation and its associated industry team members, are described. In just three years, engineering work on this combined-cycle powerplant type evolved, from its initial NASA-sponsored reusable space transportation system study status, into a U.S. Air Force/Navy-supported exploratory development program as a candidate 4.5 high-performance military aircraft engine. Bridging a productive transition from the spaceflight to the aviation arena, this case history supports the expectation that fully-integrated airbreathing/rocket propulsion systems hold high promise toward meeting the demanding propulsion requirements of tomorrow's aircraft-like Spaceliner class transportation systems. Lessons to be learned from this "SERJ Story" are offered for consideration by today's advanced space transportation and combined-cycle propulsion researchers and forward-planning communities.

Escher, William J. D.↗