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Simulation of a Full-Scale Crash Test of a Fokker F28 Fellowship Aircraft
Get PDFIn June 2019, a full-scale crash test of a Fokker F28 Fellowship aircraft was conducted as part of a joint National Aeronautics and Space Administration/Federal Aviation Administration (NASA/FAA) project to investigate the performance of transport aircraft under realistic crash conditions. The test objectives were to provide data for assessment of transport aircraft crash worthiness and to generate test data for model validation. The test article was loaded with transport aircraft seats in a 3+2 configuration. A total of 24 instrumented Anthropomorphic Test Devices (ATDs) were placed in the seats and restrained. The test article weighed 33,306-lb. and, during the crash test, impacted a 2-ft. high soil bed at 65.3-ft/s forward and 31.8-ft/s vertical velocity. The full-scale crash test was simulated using the commercial nonlinear explicit transient dynamic finite element code, LSDYNA. This paper will provide a description of the test article and the crash test conditions, document the F28 full-scale model development, and present test-analysis comparisons in several categories including inertial properties, kinematic responses, structural acceleration responses, and airframe deformation and failure. In addition, test-analysis results will be quantified based on the International Organization for Standardization (ISO) 16250 curve comparison methodology
COMDES-MELT: A Turbofan Engine Icing Risk Analysis Tool, Users Manual
Get PDFThe computational tool COMDES-MELT was developed to predict the susceptibility of turbofan engines to
ice accretion when flying in an ice crystal environment. COMDES-MELT is a first-generation computational tool
that can estimate the conditions at which the accretion of ice can occur, location within the turbofan engine
compression system, and at which engine operating points within the flight trajectory. This is accomplished by
tracking the parameters of static wet bulb temperature, ice particle melt ratio, and the ice-water to airflow rates
ratio as ice crystals are ingested into the engine compression system. It has been used successfully to predict
engine operating points for simulation in an altitude wind tunnel with ice crystal ingestion. These engine tests
occur in a simulated ice crystal cloud environment. This predictive analysis has been used to generate the test
matrix in preparation for tests in the Propulsion Systems Laboratory, an altitude test facility at the NASA Glenn
Research Center. Furthermore, due to the speed of the code during an engine icing test, adjustments to the test
matrix can be provided to the test engineer in real time to focus on a particular area of ice accretion susceptibility.
The use of the COMDES-MELT code will be examined in this manual
Wildfire Smoke Particle Properties and Evolution, from Space-Based Multi-Angle Imaging
Get PDFEmitted smoke composition is determined by properties of the biomass burning source and ambient ecosystem. However, conditions that mediate the partitioning of black carbon (BC) and brown carbon (BrC) formation, as well as the spatial and temporal factors that drive particle evolution, are not understood adequately for many climate and air-quality related modeling applications. In situ observations provide considerable detail about aerosol microphysical and chemical properties, although sampling is extremely limited. Satellites offer the frequent global coverage that would allow for statistical characterization of emitted and evolved smoke, but generally lack microphysical detail. However, once properly validated, data from the National Aeronautics and Space Administration (NASA) Earth Observing Systems Multi-Angle Imaging Spectroradiometer (MISR) instrument can create at least a partial picture of smoke particle properties and plume evolution. We use in situ data from the Department of Energys Biomass Burning Observation Project (BBOP) field campaign to assess the strengths and limitations of smoke particle retrieval results from the MISR Research Aerosol (RA) retrieval algorithm. We then use MISR to characterize wildfire smoke particle properties and to identify the relevant aging factors in several cases, to the extent possible. The RA successfully maps qualitative changes in effective particle size, light absorption, and its spectral dependence, when compared to in situ observations. By observing the entire plume uniformly, the satellite data can be interpreted in terms of smoke plume evolution, including size-selective deposition, new-particle formation, and locations within the plume where BC or BrC dominates
On the Use of Complexity Algorithms: a Cautionary Lesson from Climate Research
Get PDFComplexity algorithms provide information about datasets which is radically different from classical moment statistics. Instead of focusing on the divergences from central values, they quantify other characteristics such as order, pattern repetitions, or the existence of attractors. However, those analyses must be done with the proper statistical treatment, which is, unfortunately, not always the case. In this contribution, I provide an example of the hazards of applying complexity measures without sufficient care by correcting a previously published analysis that aimed to quantify the complexity of climate. I clarify some misconceptions about the use of Sample Entropy and revise the incorrect assessments and conclusions drawn from the previous misapplication of the methods
Evaluating Drought Indices for Early Warning in East and Southern Africa
Get PDFSparsely populated regions of east and southern Africa often have little ground based data to monitor drought, crops, and water resources. The Regional Hydrologic Extremes Assessment System (RHEAS) is a NASA supported data assimilation framework that combines both a hydrologic and crop model, which provide another monitoring approach. RHEAS can also be run in forecast mode, providing outlook on drought and crop yield
Model Based Diagnostics and Prognostics Framework for Systems Health Management
Get PDFIn order to tackle and solve the system health prediction problem, it is essential to have awareness of the current state and health of the system, especially since it is necessary to perform condition-based predictions. To be able to accurately predict the future state of any system, it is required to possess knowledge of its current and future operations. Given models of the current and future system behavior, the general approach of model-based prognostics can be employed as a solution to the prior stated prediction problem. In case of electric aircrafts, computing remaining flying time is safety-critical, since an aircraft that runs out of power (battery charge) while in the air will eventually lose control leading to catastrophe. In order to tackle and solve the prediction problem, it is essential to have awareness of the current state and health of the system, especially since it is necessary to perform condition-based predictions. To be able to predict the future state of the system, it is also required to possess knowledge of the current and future operations of the vehicle. This presentation will cover a physics based-modeling approach implemented for case-studies in battery and composite structures for prognostics. Given models of the current and future system behavior, a general approach of model-based prognostics can be employed as a solution to the prediction problem and further for decision making
Effect of Pressure on the Activity Coefficients of Au and Other Siderophile Elements in Liquid Fe-Si Alloys
Get PDFLight elements can alloy into the iron cores of terrestrial planetary bodies. It is estimated that the Earths core contains ~10% of a light element, most likely a combination of S, C, Si, and O with Si probably being the most abundant. Si dissolved into Fe metal liquids can have a significant influence on the activity coefficients of siderophile elements, and thus the partitioning behavior of those elements between the core and mantle. Many of these elements have been investigated extensively at ambient pressure, and studies up to 1 GPa are becoming more common, but few have been studied at pressures above this. The formation of the Earths core has been estimated to have formed at pressures between 40-60 GPa, so investigating the effect pressure has on Sis influence on siderophile element partitioning is important for modeling core formation in the Earth and smaller planets. Pressure is well known to influence volumetric properties of metallic and silicate liquids, and oxygen fugacity (e.g., [10,11]), but less is known about its effect on activity coefficients (e.g., [12]). Some activity coefficients depend strongly upon the Si content of Fe liquids, and the concentration of siderophile elements such as P, Sb, and As in the terrestrial mantle is easily influenced by dissolved Si in the core. Thus, isolating the effect of pressure on activity coefficients in general is critical in quantitative analysis of core formation models. In this work, we investigate the effect variable Si content has on the partitioning of Au between Fe metal and silicate melt at 10 GPa and 2373 K, with the intention of comparing the behavior to that already investigated at lower pressures. In addition, P, V, Mn, Ga, Zn, Cd, Sn, W, Pb, and Nb were also measured and could thus be included in the assessment of potential pressure effects
Open Advanced Air Mobility Project Vertiport and Route Decision Support Tool
Get PDFThe expected rise of Urban Air Mobility (UAM) presents local and regional planners with unique challenges. Aviation-based urban transportation requires analysis of new planning factors in addition to traditional factors. For example, the planner must be able to analyze community impacts (e.g. aircraft noise) and restrictions (e.g. airspace restrictions, terrain avoidance). This presentation presents a software modeling tool to address these planning challenges
The Role of Solar Wind Hydrogen in Space Weathering: Insights from Laboratory-Irradiated Northwest Africa 12008
Get PDFMicrometeoroid impacts, solar wind plasma interactions, and regolith gardening drive the complicated and nuanced mechanism of space weathering (or optical maturation); a process by which a materials optical properties are changed as a result of chemical and physical alterations at the surface of grains on airless bodies. Reddened slopes, attenuated absorption bands, and an overall reduction in albedo in the visible and near-IR wavelength ranges are primarily the result of native iron nanoparticle (npFe0) production within glassy rims that form from sputtering and vaporization. The sizes and abundance of these particles provide information about the relative surface exposure age of a particular grain. In addition, many studies have indicated that composition greatly affects the rate at which optical maturation occurs. Despite our understanding of how npFe0 affects optical signatures, the relative roles of micrometeoroid bombardment and solar wind interactions remains undetermined. To simulate the early effects of weathering by the solar wind and to determine thresholds for optical change with respect to a given mineral phase, we irradiated a fine-grained lunar basalt with 1 keV H+ to a fluence of 6.4 x 1016 H+ per sq.cm. Surface alterations within four phases have been evaluated using transmission electron microscopy (TEM). We found that for a given fluence of H+, the extent of damage acquired by each grain was dependent on its composition. No npFe(0) was produced in any of the phases evaluated in this study. These results are consistent with many previous studies conducted using ions of similar energy, but they also provide valuable information about the onset of space weathering and the role of the solar wind during the early stages of optical maturation