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This paper presents the results of an analysis to calculate the cumulative, effective atomic oxygen (AO) flux impinging on short-duration EVA tethers used to secure panel NOD1/C2-02 and panel LAB/C2-03. Shadowing from the ram reduces the AO flux on much of the Node 1 panel. On the Lab panel, the tethers are essentially in the ram flux. Table 1 summarizes the results of the analysis for Node 1 and the US Lab panels.
This paper summarizes major theoretical results for pulse detonation engine performance taking into account real gas chemistry, as well as significant performance differences resulting from the presence of ram and compression heating. An unsteady CFD analysis, as well as a thermodynamic cycle analysis, was conducted in order to determine the actual and the ideal performance for an air-breathing pulse detonation engine (PDE) using either a hydrogen-air or ethylene-air mixture over a flight Mach number range from 0 to 4. The results clearly elucidate the competitive regime of PDE application relative to ramjets and gas turbines.
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A software method has been developed that is applicable for analyzing cylindrical and partially cylindrical objects inspected using computed tomography (CT). This method involves unwrapping and re-slicing data so that the CT data from the cylindrical object can be viewed as a series of 2D sheets (or flattened onion skins ) in addition to a series of top view slices and 3D volume rendering. The advantages of viewing the data in this fashion are as follows: (1) the use of standard and specialized image processing and analysis methods is facilitated having 2D array data versus a volume rendering; (2) accurate lateral dimensional analysis of flaws is possible in the unwrapped sheets versus volume rendering; (3) flaws in the part jump out at the inspector with the proper contrast expansion settings in the unwrapped sheets; and (4) it is much easier for the inspector to locate flaws in the unwrapped sheets versus top view slices for very thin cylinders. The method is fully automated and requires no input from the user except proper voxel dimension from the CT experiment and wall thickness of the part. The software is available in 32-bit and 64-bit versions, and can be used with binary data (8- and 16-bit) and BMP type CT image sets. The software has memory (RAM) and hard-drive based modes. The advantage of the (64-bit) RAM-based mode is speed (and is very practical for users of 64-bit Windows operating systems and computers having 16 GB or more RAM). The advantage of the hard-drive based analysis is one can work with essentially unlimited-sized data sets. Separate windows are spawned for the unwrapped/re-sliced data view and any image processing interactive capability. Individual unwrapped images and un -wrapped image series can be saved in common image formats. More information is available at http://www.grc.nasa.gov/WWW/OptInstr/ NDE_CT_CylinderUnwrapper.html.
Application of a viscous shock-layer analysis to the calculation of nonequilibrium-flow species distributions in the plasma layer of a blunt-nosed vehicle at high altitudes. The theoretical electron-density results obtained are in good agreement with those measured in flight for a hemisphere-9 deg cone entry vehicle. The flight measurements were obtained using electrostatic probes that protruded well into the shock layer. In addition, the theoretically obtained heavy-particle translational temperatures appear to agree fairly well with the electron temperatures that were measured in the flight experiments using voltage-swept thin-wire electrostatic probes. The influence of the reaction rate coefficients on the calculated electron densities has been assessed and shown to be within the uncertainty in the flight data. The theoretical results demonstrate the importance of including in the chemical model the positive ions N2(+), O2(+), N(+), and O(+), in addition to NO(+), for the high altitudes and velocities considered.
An air drying process has been analyzed which is intended to reduce the water vapor content of a stratospheric sample to below one part per million by weight, based upon the removal of the water as it passes through a phosphorous pentoxide absorber. The analysis indicates that the method is feasible. Dependence on ram pressure to maintain flow through the absorber appears questionable and consideration should be given to other means.
In the present study, a numerical assessment of the performance of fuselage boundary layer ingestion (BLI) propulsion techniques was conducted. This study is an initial investigation into coupling the aerodynamics of the fuselage with a BLI propulsion system to determine if there is sufficient potential to warrant further investigation of this concept. Numerical simulations of flow around baseline, Boundary Layer Controlled (BLC), and propelled boundary layer controlled airships were performed. Computed results showed good agreement with wind tunnel data and previous numerical studies. Numerical simulations and sensitivity analysis were then conducted on four BLI configurations. The two design variables selected for the parametric study of the new configurations were the inlet area and the inlet to exit area ratio. Current results show that BLI propulsors may offer power savings of up to 85% over the baseline configuration. These interim results include the simplifying assumption that inlet ram drag is negligible and therefore likely overstate the reduction in power. It has been found that inlet ram drag is not negligible and should be included in future analysis.
This paper discusses a Reliability, Availability, and Maintainability (RAM) independent assessment conducted to support the refurbishment of the Compressor Station at the NASA Langley Research Center (LaRC). The paper discusses the methodologies used by the assessment team to derive the repair by replacement (RR) strategies to improve the reliability and availability of the Compressor Station (Ref.1). This includes a RAPTOR simulation model that was used to generate the statistical data analysis needed to derive a 15-year investment plan to support the refurbishment of the facility. To summarize, study results clearly indicate that the air compressors are well past their design life. The major failures of Compressors indicate that significant latent failure causes are present. Given the occurrence of these high-cost failures following compressor overhauls, future major failures should be anticipated if compressors are not replaced. Given the results from the RR analysis, the study team recommended a compressor replacement strategy. Based on the data analysis, the RR strategy will lead to sustainable operations through significant improvements in reliability, availability, and the probability of meeting the air demand with acceptable investment cost that should translate, in the long run, into major cost savings. For example, the probability of meeting air demand improved from 79.7 percent for the Base Case to 97.3 percent. Expressed in terms of a reduction in the probability of failing to meet demand (1 in 5 days to 1 in 37 days), the improvement is about 700 percent. Similarly, compressor replacement improved the operational availability of the facility from 97.5 percent to 99.8 percent. Expressed in terms of a reduction in system unavailability (1 in 40 to 1 in 500), the improvement is better than 1000 percent (an order of magnitude improvement). It is worthy to note that the methodologies, tools, and techniques used in the LaRC study can be used to evaluate similar high value equipment components and facilities. Also, lessons learned in data collection and maintenance practices derived from the observations, findings, and recommendations of the study are extremely important in the evaluation and sustainment of new compressor facilities.
Following the discovery of intense vehicle glow of the Space Shuttle on the STS-3 mission, a new experiment to probe this phenomenon was developed and flown on the Shuttle STS-4 mission. A conventional camera was equipped with an objective transmission grating and several photographic exposures were taken of the Shuttle tail from the aft flight deck window. Vehicle glow surrounding Shuttle surfaces exposed to the ram direction was observed on a long (400 second) exposure. From analysis of the resulting spectral data it appears that the Shuttle glow has a diffuse spectral component in the region 6300 to 8000A. In addition, it has been possible to assess the spectral character of light emitted by the firing of a reaction control system thruster. Our data show that the light emitted from the thruster gases is confined to wavelengths shorter than 7200A.
This presentation summarizes studies ongoing under the "What's Next in Regional (Air) Mobility" umbrella within the Intercenter Systems Analysis Team. It includes a look at the Regional Air Mobility (RAM) market potential, simulation of a RAM passenger network to gather statistics, and scrutinizes airport energy needs to support RAM operations. It also references a companion presentation provided by the DOT Volpe Center presented by Jacob Wishart related to RAM market and demand estimates.
Data analysis and numerical modeling efforts that are related to the 1986 Satellite Precipitation and Cloud Experiment (SPACE) are discussed. Progress during this period includes the following: further testing and development of the RAMS numerical modeling system on the Alabama CRAY X-MP/24; a continuation of the observational analysis of the 13 July 1986 mesoscale convective system (MCS); and an initial investigation of a small MCS that formed over the COHMEX region on 15 July 1986. Details for each of these individual tasks are given.
Numerical analysis of techniques for separating space shuttles by separation rockets, spring loaded ram, nonignitable gas ejector, or pyrotechnic ram
The keynote address was the problem of physical initialization of mesoscale models. The classic purpose of physical or diabatic initialization is to reduce or eliminate the spin-up error caused by the lack, at the initial time, of the fully developed vertical circulations required to support regions of large rainfall rates. However, even if a model has no spin-up problem, imposition of observed moisture and heating rate information during assimilation can improve quantitative precipitation forecasts, especially early in the forecast. The two key issues in physical initialization are the choice of assimilating technique and sources of hydrologic/hydrometeor data. Another example of data assimilation in mesoscale models was presented in a series of meso-beta scale model experiments with and 11 km version of the MASS model designed to investigate the sensitivity of convective initiation forced by thermally direct circulations resulting from differential surface heating to four dimensional assimilation of surface and radar data. The results of these simulations underscore the need to accurately initialize and simulate grid and sub-grid scale clouds in meso- beta scale models. The status of the application of the CSU-RAMS mesoscale model by the NOAA Forecast Systems Lab for producing real-time forecasts with 10-60 km mesh resolutions over (4000 km)(exp 2) domains for use by the aviation community was reported. Either MAPS or LAPS model data are used to initialize the RAMS model on a 12-h cycle. The use of MAPS (Mesoscale Analysis and Prediction System) model was discussed. Also discussed was the mesobeta-scale data assimilation using a triply-nested nonhydrostatic version of the MM5 model.
An examination of the interactions between proposed "solar sail" propulsion systems with photovoltaic energy generation capabilities and the space plasma environments. Major areas of interactions ere: Acting from high voltage arrays, ram and wake effects, V and B current loops and EMI. Preliminary analysis indicates that arcing will be a major risk factor for voltages greater than 300V. Electron temperature enhancement in the wake will be produce noise that can be transmitted via the wake echo process. In addition, V and B induced potential will generate sheath voltages with potential tether like breakage effects in the thin film sails. Advocacy of further attention to these processes is emphasized so that plasma environmental mitigation will be instituted in photovoltaic sail design.
The purpose of this abstract is to share data from preliminary modeling of meteor dynamics of the 08 Jan 2014 bolide which occurred north of Papua New Guinea as reported by US Department of Defense (DoD) sensors. A hypothesis has been proposed that this event was of interstellar origin. DoD data indicate that this bolide was produced by a meteor moving 44.8 km/s at only 18.7 km altitude, which describes a velocity profile that is exceptional in velocity, much less at such a low altitude. The Jörmungandr model developed by the author for dark flight modeling was adapted to estimate the luminous flight profile of this body. While this model has significant limits in use for luminous flight and all results must be viewed as preliminary, analysis indicates there is a compelling need for further investigation. Calculation of ram pressure by this object indicate that an iron or iron-rich meteorite 0.5m in diameter is a possible explanation for the reported DoD data.
This investigation involved the analysis of electron plasma and heavy ion composition measurements made by the COPERNIC (COmplete Positive ion, Electron, and Ram Negative Ion measurements near Comet Halley) plasma experiment during the close fly-by of Halley by the European Space Agency's Giotto spacecraft. The experiment provided measurements of the full 3-dimensional distribution of 10 eV-30 keV electrons, and mass analysis of cold cometary ions from 10-210 amu. The analysis of the COPERNIC data has yielded some remarkable results, including: The discovery of negatively charged ions in the inner coma; the discovery of far heavier (mass is greater than 50 amu) ions than predicted, dominated by complex molecular ions made up of C, H, O, and N; the discovery of an adiabatic heating effect on electrons from the compression of the solar wind plasma; the identification of several organic and sulfur bearing ions; and the discovery of a new 'mystery region' where electrons are accelerated to high energies. These discoveries were in addition to the detailed analysis of 'expected' features at Comet Halley. Although this grant has expired, analysis continues on the data at a low (unfunded) level, and it is expected that more significant results will be obtained. A bibliography of the papers resulting from this research is attached, and a copy of each paper is included.
The design of the Space Station presented new challenges in the selection and qualification of thermal control materials that would survive in low Earth orbit for a duration of up to 30 years. Prior to LDEF, flight data were obtained from Orbiting Solar Observatory (OSO) satellites, a number of Orbiter flights, and limited ground tests. The excellent data obtained from the OSO satellites were based on calorimetry and temperature measurements which were transmitted to Earth; these satellites were not recovered. For some of these flight experiments it was difficult to distinguish between changes due to contamination, atomic oxygen (AO), ultraviolet radiation (UV), particle radiation and the synergistic effects between them. The data from Shuttle flights were primarily focused on developing a better understanding of atomic oxygen (AO) effects. Although UV and AO were present, the relatively short duration of the Orbiter flights, about one week, was viewed as too short to show the effects from UV or possible synergistic interactions with AO and contamination. At the beginning of the program in 1989 there was no established design data base for AO resistant thermal control coatings for the Space Station. Then came the Long Duration Exposure Facility (LDEF). It provided the first long life data for materials exposed and recovered from space with a characterized environment. Post flight analysis proved data on the effects of contamination on optical properties in the ram (velocity) and wake directions and the erosion of Teflon and multilayer insulation (MLI) covers. The results from LDEF confirmed and, in some cases, modified the approach used for the Space Station, as well as helped to focus our development activities. These development activities resulted in a number of new technical solutions which are applicable to many spacecraft surfaces and missions. LDEF also showed the detrimental effects that could occur from silicone contamination, an issue that has not been completely resolved. An investigation was initiated in 1993 on the effects of silicone contamination and was continuing at the time this paper was prepared.
Described is work performed under NASA Grant NAG8-654 for the period 15 March to 15 September 1988. This work entails primarily data analysis and numerical modeling efforts related to the 1986 Satellite Precipitation and Cloud Experiment (SPACE). In the following, the SPACE acronym is used along with the acronym COHMEX, which represents the encompassing Cooperative Huntsville Meteorological Experiment. Progress made during the second half of the first year of the study included: (1) installation and testing of the RAMS numerical Modeling system on the Alabama CRAY X-MP/24; (2) a start on the analysis of the mesoscale convection system (MCS) of 13 July 1986 COHMEX case; and (3) a cursory examination of a small MCS that formed over the COHMEX region on 15 July 1986. Details of each of these individual tasks are given.