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All sourcesNASA NTRSDOE OSTI
NASA NTRS2010

Converting a C-130 Hercules into a Compound Helicopter: A Conceptual Design Study

This study presents the performance and weight changes for a Compound C-130 as compared to the Baseline C-130H Hercules, using NDARC as the primary analysis tool. First, the C-130H was modeled within NDARC, from which performance at various conditions and a parametric weight statement were generated. Then, the C-130H NDARC file was modified to represent the Compound C-130, which was then put through the same performance analysis as the C-130H. A parametric weight statement was also calculated for the Compound C-130, which allowed for comparison to the C-130H. As part of the modeling of the Compound C-130, a Rotor Design Spreadsheet was created that would allow the direct calculation of the weight of the main rotors being added. Using composite materials led to considerable weight savings for both the rotor system and the hub weights. These weight savings are reflected in the NDARC Technology Factors which were determined to be 0.71 and 0.5 for the rotor blades and the hub/hinge system, respectively. Such Technology Factors suggest that using composites for other components could drastically lighten the Operating Empty Weight of the aircraft. The weight statements show the weights for each of the components on each aircraft. It is quite evident that the Compound C-130 has a higher Operating Empty Weight due to the addition of the two main rotors and a drive system to connect each engine group on the wing tips. Upon further analysis, the main weight driver is the drive system. While the main rotor/hub/hinge weight increase is to be expected, the weight increase due to the transmission drive and gear boxes are cause for concern. Unless a method can be found of reducing the weight of the drive system, the weight penalty makes the Compound a C-130 an inefficient aircraft in terms of payload/fuel capacity. Possible solutions are either off-loading some of the power requirements through the drive system or using composite materials in the construction of the drive system. The performance of the Compound C-130 versus the C-130H shows a clear need for more powerful engines than are currently present on the C-130H. This would also adversely affect the Operating Empty Weight since a larger power plant requires more weight. However, one advantage that the Compound C-130 presents is the ability to hover and operate at low speeds in Helicopter Mode. While the C-130H is unable to travel at speeds lower than its stall speed, the Compound C-130 is able to hover using the main rotors. Thus, the Compound C-130 is able to operate independent of runways, let alone the condition of the nearest runway. Ultimately, the Compound C-130 is an effective aircraft in theaters requiring VTOL aircraft due to geographical considerations in terms or performance. Unfortunately, the weight penalty associated with converting the C-130H to a Compound C-130 suggests that further work in the area of the drive systems is required.

Kottapalli, Anjaney P.↗
NASA NTRS2018

NASA’s Mid-Atlantic Communities and Areas at Intensive Risk Demonstration: Translating Compounding Hazards to Societal Risk

Remote sensing provides a unique perspective on our dynamic planet, tracking changes and revealing the course of complex interactions. Long term monitoring and targeted observation combine with modeling and mapping to provide increased awareness of hydro-meteorological and geological hazards. Disasters often follow hazards and the goal of NASA’s Disasters Program is to look at the earth as a highly coupled system to reduce risk and enable resilience. Remote sensing and geospatial science are used as tools to help answer critical questions that inform decisions. Data is not the same as information, nor does understanding of processes necessarily translate into decision support for disaster preparedness, response and recovery. Accordingly, NASA is engaging the scientific and decision-support communities to apply remote sensing, modeling, and related applications in Communities and Areas at Intensive Risk (CAIR). In 2017, NASA’s Applied Sciences Disasters Program hosted a regional workshop to explore these issues with particular focus on coastal Virginia and North Carolina. The workshop brought together partners in academia, emergency management, and scientists from NASA and partnering federal agencies to explore capabilities among the team that could improve understanding of the physical processes related to these hazards, their potential impact to changing communities, and to identify methodologies for supporting emergency response and risk mitigation. The resulting initiative, the mid-Atlantic CAIR project, demonstrates the ability to integrate satellite derived earth observations and physical models into actionable, trusted knowledge. Severe storms and associated storm surge, sea level rise, and land subsidence coupled with increasing populations and densely populated, aging critical infrastructure often leave coastal regions and their communities extremely vulnerable. The integration of observations and models allow for a comprehensive understanding of the compounding risk experienced in coastal regions and enables individuals in all positions make risk-informed decisions. This initiative uses a representative storm surge case as a baseline to produce flood inundation maps. These maps predict building level impacts at current day and for sea level rise (SLR) and subsidence scenarios of the future in order to inform critical decisions at both the tactical and strategic levels. To accomplish this analysis, the mid-Atlantic CAIR project brings together Federal research activities with academia to examine coastal hazards in multiple ways: 1) reanalysis of impacts from 2011 Hurricane Irene, using numerical weather modeling in combination with coastal surge and hydrodynamic, urban inundation modeling to evaluate combined impact scenarios considering SLR and subsidence, 2) remote sensing of flood extent from available optical imagery, 3) adding value to remotely sensed flood maps through depth predictions, and 4) examining coastal subsidence as measured through time-series analysis of synthetic aperture radar observations. Efforts and results are published via ArcGIS story maps to communicate neighborhoods and infrastructure most vulnerable to changing conditions. Story map features enable time-aware flood mapping using hydrodynamic models, photographic comparison of flooding following Hurricane Irene, as well as visualization of heightened risk in the future due to SLR and land subsidence.

Rogers, Laura↗
NASA NTRS2012

Frequency Shift During Mass Properties Testing Using Compound Pendulum Method

During mass properties testing on the X-48B Blended Wing Body aircraft (The Boeing Company, Chicago, Illinois) at the National Aeronautics and Space Administration Dryden Flight Research Center, Edwards, California, large inertia measurement errors were observed in results from compound pendulum swings when compared to analytical models. By comparing periods of oscillations as measured from an average over the test period versus the period of each oscillation, it was noticed that the frequency of oscillation was shifting significantly throughout the test. This phenomenon was only noticed during compound pendulum swings, and not during bifilar pendulum swings. The frequency shift was only visible upon extensive data analysis of the frequency for each oscillation, and did not appear in averaged frequency data over the test period. Multiple test articles, test techniques, and hardware setups were used in attempts to eliminate or identify the cause of the frequency shift. Plotting the frequency of oscillation revealed a region of minimal shift that corresponded to a larger amplitude range. This region of minimal shift provided the most accurate results compared to a known test article; however, the amplitudes that produce accurate inertia measurements are amplitudes larger than those generally accepted in mass properties testing. This paper examines two case studies of the frequency shift, using mass properties testing performed on a dummy test article, and on the X-48B Blended Wing Body aircraft.

Wolfe, David↗
NASA NTRS1981

A meteor-ablation model of the sodium and potassium layers

Recent results on meteor ablation are used as input to a model in which ablation (or evaporation) is the source and deposition on dust particles is the sink. The dust comes from recondensation of the rest of the meteor vapor. An excellent match is found to the observed characteristics of the sodium layer. It is argued that the high-latitude winter maximum of abundance (and layer height) is due to the much lower rate of ionization there and over the polar cap. The computations show the required factor of 4-5 and also match the height variation. To keep the ion density from being too large, downward electrodynamic transport at about 50 cm/sec must be invoked. The different behavior and low abundance of potassium require an additional sink. The one proposed is Penning ionization by metastable excited O2. Inherent in the model is that sodium and its compounds reside almost entirely on dust particles below 80 km. Large abundances in the free form at stratospheric heights are very unlikely and are not a good explanation of observed ambient ions.

Hunten, D. M.↗
NASA NTRS1982

Dynamic mechanical analysis and organization/storage of data for polymetric materials

Dynamic mechanical analysis was performed on a variety of temperature resistant polymers and composite resin matrices. Data on glass transition temperatures and degree of cure attained were derived. In addition a laboratory based computer system was installed and data base set up to allow entry of composite data. The laboratory CPU termed TYCHO is based on a DEC PDP 11/44 CPU with a Datatrieve relational data base. The function of TYCHO is integration of chemical laboratory analytical instrumentation and storage of chemical structures for modeling of new polymeric structures and compounds

Rosenberg, M.↗
NASA NTRS1983

A model study of the effects of intermittent loss on odd nitrogen concentrations in the lower troposphere

A time-dependent box model of the lower troposphere which includes a description of photochemical and physical processes has been developed. This model has been applied to the calculation of nitric acid and NO(x)(NO + NO2) concentrations over a diurnal cycle which includes precipitation. Nitric acid concentrations and the HNO3/NO(x) ratio are found to be highly variable under the assumptions regarding the frequency, duration, and intensity of precipitation employed in this model. The chemistry of odd nitrogen compounds during the night is potentially important in establishing the level of nitric acid in the lower troposphere. These calculations also indicate that relatively large errors may occur when the continuity equation describing nitric acid variations is averaged over a diurnal cycle which includes precipitation. Interpretation of simultaneous measurements of HNO3 and NO(x) will require some knowledge of the history of the observed air mass and may require an improved understanding of nighttime odd nitrogen chemistry.

Stewart, R. W.↗
NASA NTRS1986

A priori predictions of the rotational constants for protonated formaldehyde and protonated methanol

Protonated formaldehyde and protonated methanol are candidate interstellar molecules and models for classes of protonated oxygen compounds. Ab initio molecular orbital theory has been used to compute rotational constants to guide spectroscopic searches both in the laboratory and in space. The ab initio results are empirically correct to account for systematic deficiencies in the theory and zero-point vibrational effects; they are expected to be accurate to about + or - 2 percent. For H2COH(+) the resultant constants are (in GHz) A = 194.3, B = 34.28, and C = 29.14; for H3COH2(+) A = 103.7, B = 21.18, and C = 20.30.

Defrees, D. J.↗
NASA NTRS1996

Haze Formation is an Important Sink for HCN on Titan

Titan's organic haze is potentially an important sink of photochemically produced carbon and nitrogen compounds. An assortment of microphysical haze models all suggest that the haze production rate is 10(exp -14) gm per square centimeter per second, within a factor of two. Spectral analysis of laboratory tholins compared to Titan's geometric albedo spectrum suggest that the laboratory material is a good analog to Titan's haze. The laboratory material has an elemental composition given approximately by C4H4N, with an uncertainty in the C/N ratio of a factor of two. Thus, the haze represents a sink for C of 4 x 10(exp 8) per square centimeter per second, and a sink for N of 1 x 10(exp 8) per square centimeter per second. The C sink is small compared to condensation of hydrocarbons but the sink for N is comparable to the total production rate of HCN. Because estimates of the eddy diffusion profile on Titan have been based on the HCN profile, inclusion of this additional sink for N will affect estimates for all transport processes in Titan's atmosphere.

McKay, Christopher P.↗
NASA NTRS2022

Un-Numbered Operational Areas PRL 229 Railroad Tie Disposal Area Pond Confirmation Sampling Report

This Confirmatory Sampling (CS) Report (CSR) was prepared for the National Aeronautics and Space Administration (NASA), Kennedy Space Center (KSC), Florida in accordance with the CS Work Plan (CSWP) (HGL, 2022a). The CSR summarizes investigation activities performed on the Railroad Tie Disposal Area (RTDA) of the Un-Numbered Operational Areas (UNOA), Potential Release Location (PRL) 229 located at KSC. HydroGeoLogic, Inc. (HGL) prepared this report under Contract Number 80KSC019D0012. The purpose of the CSR is to provide information to evaluate the level of potential contamination in surface water and sediment samples collected from the RTDA PRL 229 Pond and determine if contaminants pose unacceptable risks to ecological receptors. The CSR provides analytical data of 10 sets of surface water and sediment samples collected in 2021. Surface water samples were analyzed for volatile organic compounds (VOCs), semi-volatile organic compounds (SVOCs), polynuclear aromatic hydrocarbon (PAHs), metals, hardness, and salinity, while sediment samples were analyzed for metals, total organic carbon (TOC), SVOCs, PAHs, and total petroleum hydrocarbons (TPH). The CSR includes a Screening Level Ecological Risk Assessment (SLERA) conducted under KSC’s Resource Conservation and Recovery Act (RCRA) Corrective Action Program to determine if unacceptable risks to ecological receptors exist at PRL 229 Pond. Metals and PAHs were detected in surface water samples, including detections of antimony, arsenic, barium, calcium, copper, lead, magnesium, thallium, zinc, anthracene, benzo(a)anthracene, benzo(a)pyrene, benzo(b)fluoranthene, benzo(g,h,i)perylene, benzo(k)fluoranthene, chrysene, dibenzo(a,h)anthracene, fluoranthene, indeno(1,2,3-c,d)pyrene and pyrene. Based on measured salinity (1.03 to 1.21 parts per thousand), the pond was identified as freshwater. Sediment analytical results also contained detections of metals and PAHs, including antimony, arsenic, barium, beryllium, cadmium, chromium, copper, lead, mercury, nickel, selenium, thallium, zinc, anthracene benzo(a)anthracene, benzo(a)pyrene, benzo(b)fluoranthene, benzo(g,h,i)perylene, benzo(k)fluoranthene, chrysene, dibenzo(a,h)anthracene, fluoranthene, indeno(1,2,3-c,d)pyrene and pyrene. Potential risks to ecological receptors were evaluated in accordance with the SLERA Work Plan and the Decision Process Document for the Resource Conservation and Recovery Act (RCRA) Corrective Action Program at KSC (DPD) (Geosyntec, 2019), and using the 2021 sediment and surface water analytical results. Potential ecological receptors evaluated in the SLERA include the aquatic community, benthic invertebrates, aquatic birds, and aquatic mammals. The SLERA included Steps 2a through 2c of the Ecological Risk Assessment (ERA) process in accordance with the DPD. Using multiple lines of evidence, the SLERA concluded that many of the detected analytes are present at concentrations similar to those in background or reference locations at KSC, and/or at concentrations that would not pose a significant risk to ecological communities. There are no screening values available for the avian community, and PAHs are bioaccumulative compounds. For this reason, food web modeling was completed as a supplement to Step 2c to provide a quantitative evaluation of this exposure pathway. Food web modeling indicates that PAHs are unlikely to pose a risk to birds exposed to site sediment and surface water. Based on the results of the SLERA, the contaminants in sediment and surface water pose no to minimal risk to the ecological communities that could live or forage at the site. Based on the results of the SLERA, no further study is recommended for the RTDA Pond at PRL 229.

Confirmation Sampling↗
NASA NTRS2000

Evolution of Bromoform in a Global Chemistry and Transport Model

It is well known that many chlorine and bromine compounds that are inert in the troposphere are destroyed in the stratosphere and contribute to the stratospheric burden of reactive chlorine and bromine species. But the contribution from those chlorine and bromine compounds which are reactive in the troposphere is less certain because it is not known whether convection can transport these gases to the upper troposphere rapidly enough to overcome their short tropospheric lifetimes. We examine this issue using a three-dimensional chemistry and transport model to simulate the evolution of three gases which have surface sources, bromoform (CHBr3), methyl chloroform (CH3CCl3), and carbon dioxide (CO2). Our objective is to determine if CHBr3 might enhance the lower stratospheric burden of reactive bromine. The other two gases provide tests of the quality of the simulation. Both CHBr3 and CH3CCl3 are destroyed in the troposphere by reaction with hydroxyl (OH), whose latitudinal and monthly variation is provided by a two-dimensional model and upon which a diurnal variation is imposed. Comparison of the lifetime of CH3CCl3 computed from observations (5 years) with the lifetime computed from the simulation provides an integrated test of the model's transport and photochemistry. Observations also show that CO2 exhibits a strong seasonal cycle in the northern hemisphere troposphere that is not propagated directly across the tropopause into the lower stratosphere. Thus, maintenance of the observed troposphere-stratosphere distinctness of CO2 in the presence of convection is a critical benchmark for meeting our objective.

Douglass, Anne R.↗
NASA NTRS1990

Scientific Assessment of Stratospheric Ozone: 1989, volume 2. Appendix: AFEAS Report

The results are presented of the Alternative Fluorocarbon Environmental Acceptability Study (AFEAS), which was organized to evaluate the potential effects on the environment of alternate compounds targeted to replace fully halogenated chlorofluorocarbons (CFCs). All relevant current scientific information to determine the environmental acceptability of the alternative fluorocarbons. Special emphasis was placed on: the potential of the compounds to affect stratospheric ozone; their potential to affect tropospheric ozone; their potential to contribute to model calculated global warming; the atmospheric degradation mechanisms of the compounds, in order to identify their products; and the potential environmental effects of the decomposition products. The alternative compounds to be studied were hydrofluorocarbons (HFCs) with one or two carbon atoms and one or more each of fluorine and hydrogen.

Source record↗
NASA NTRS1995

Photochemical modeling of Titan's atmosphere

We have developed a new photochemical model of Titan's atmosphere which includes all the important compounds and reactions in spherical geometry from the surface to 1240 km. Compared to the previous model of Yung et al. (1984), the most significant recent change in the reactions used is the updated methane dissociation scheme (Mordaunt et al. 1993). Moreover, the transfer of the solar radiation in the atmosphere and the photolysis rates have been calculated by using a Monte Carlo code. Finally, the eddy diffusion coefficient profile is adjusted in order to fit the mean vertical distribution of HCN retrieved from millimeter groundbased observations of Tanguy et al. (1990); using new values for the boundary flux of atomic nitrogen (Strobel et al. 1992). We have run the model in both steady-state and diurnal modes, with 62 species involved in 249 reactions. There is little difference between diurnal and steady-state results. Overall our results are in a closer agreement with the abundances inferred from the Voyager infrared measurements at the equator than the Yung et al. results. We find that the catalytic scheme for H recombination invoked by Yung et al. only slightly improves the model results and we conclude that this scheme is not essential to fit observations.

Toublanc, D.↗
NASA NTRS1993

Organic matter on the early surface of Mars: An assessment of the contribution by interplanetary dust

Calculations by Anders and Chyba et al. have recently revived interest in the suggestion that organic compounds important to the development of life were delivered to the primitive surface of the Earth by comets, asteroids or the interplanetary dust derived from these two sources. Anders has shown that the major post-accretion contribution of extraterrestrial organic matter to the surface of the Earth is from interplanetary dust. Since Mars is a much more favorable site for the gentle deceleration of interplanetary dust particles than is Earth, model calculations show that biologically important organic compounds are likely to have been delivered to the early surface of Mars by the interplanetary dust in an order-of-magnitude higher surface density than onto the early Earth. Using the method described by Flynn and McKay, the size frequency distribution, and the atmospheric entry velocity distribution of IDP's at Mars were calculated. The entry velocity distribution, coupled with the atmospheric entry heating model developed by Whipple and extended by Fraundorf was used to calculate the fraction of the particles in each mass decade which survives atmospheric entry without melting (i.e., those not heated above 1600K). The incident mass and surviving mass in each mass decade are shown for both Earth and Mars.

Flynn, G. J.↗
NASA NTRS2023

The Emissions Model Intercomparison Project (Emissions-MIP): Quantifying Model Sensitivity to Emission Characteristics

Anthropogenic emissions of aerosols and precursor compounds are known to significantly affect the energy balance of the Earth–atmosphere system, alter the formation of clouds and precipitation, and have a substantial impact on human health and the environment. Global models are an essential tool for examining the impacts of these emissions. In this study, we examine the sensitivity of model results to the assumed height of SO 2 injection, seasonality of SO 2 and black carbon (BC) particulate emissions, and the assumed fraction of SO 2 emissions that is injected into the atmosphere as particulate phase sulfate (SO 4 ) in 11 climate and chemistry models, including both chemical transport models and the atmospheric component of Earth system models. We find large variation in atmospheric lifetime across models for SO 2 , SO 4 , and BC, with a particularly large relative variation for SO 2 , which indicates that fundamental aspects of atmospheric sulfur chemistry remain uncertain. Of the perturbations examined in this study, the assumed height of SO 2 injection had the largest overall impacts, particularly on global mean net radiative flux (maximum difference of −0.35 W m −2 ), SO 2 lifetime over Northern Hemisphere land (maximum difference of 0.8 d), surface SO 2 concentration (up to 59 % decrease), and surface sulfate concentration (up to 23 % increase). Emitting SO 2 at height consistently increased SO 2 and SO 4 column burdens and shortwave cooling, with varying magnitudes, but had inconsistent effects across models on the sign of the change in implied cloud forcing. The assumed SO 4 emission fraction also had a significant impact on net radiative flux and surface sulfate concentration. Because these properties are not standardized across models this is a source of inter-model diversity typically neglected in model intercomparisons. These results imply a need to ensure that anthropogenic emission injection height and SO 4 emission fraction are accurately and consistently represented in global models.

Emissions Model Intercomparison Project↗
NASA NTRS2003

Improved Crystal Quality by Detached Solidification in Microgravity

The goals of our work on detached solidification have been to: Develop a complete understanding of all of the phenomena of detached solidification; Make it possible to achieve detached solidification reproducibly; Increase crystallographic perfection through detached solidification. Specifically, we aimed in this project to: Identify a system and develop methods that would allow viewing of the melt surface and convection in the melt during detached solidification in microgravity; Improve understanding of the origination and evolution of detachment through experiments and theoretical treatments; Achieve detachment on earth. The project resulted in 14 publications, 15 presentations, completion of 2 Ph.D. theses, and completion of 2 M.S. theses. Two additional papers are currently being reviewed for publication. Copies of most of the papers are attached as appendices. Among the accomplishments are: Achievement of detached solidification of InSb on earth and determination of the conditions favoring detachment on earth. Development of a new method for coating the interior of silica growth ampoules with transparent boron nitride, which yields the high contact angles for semiconductor melts that favor detachment. Development of a new coating for the interior of Pyrex ampoules yielding very high contact angles for water and molten organic compounds. Development of a material-balance model for steady detached solidification that provides greatly improved insight into the process, both in microgravity and on earth. Dimensionless parameters were found that clarify the role of operating conditions and physical properties. The reason for the occurrence of two steady states was clarified, along with their relative stability. Observation of periodic gas tubes during directional solidification of water and organic compounds. Gas bubbles did not propagate around the periphery to yield full detachment. Failure to obtain detachment is attributed to the ready plastic deformation of these materials, so that the frozen material continues to adhere to the ampoule wall during cooling.

Regel, Liya L.↗
NASA NTRS1993

N-body realizations of compound galaxies

A prescription for constructing N-body models of galaxies consisting of more than one component is described. Spatial density profiles are realized exactly, but the phase space distribution is approximated using moments of the collisionless Boltzmann equation. While this approach is not fully rigorous, empirical tests suggest that it is adequate for studies of, e.g., interacting galaxies and the forced response of galaxies to imposed perturbations such as bars.

Hernquist, Lars↗
NASA NTRS1981

Models for protocellular photophosphorylation

Several photoreactions for transducing light energy have been analyzed for their relevance as models for protocellular photophosphorylation. Inorganic ions and compounds could have played a role in protocellular photophosphorylation. Organic catalysts may have been the next significant agents used by protocells for photophosphorylation. Membranous photophosphorylation probably became the most recent type of photoenergy transduction to be acquired by protocells; it is still used by modern cells although components of the other types of phosphorylation are found in present day cells. Recorded yields of energy-rich phosphates from the model reactions discussed are small. Arguments are advanced that such yields could have been sufficient to have fueled protocellular metabolism, which was probably very slow compared to modern cellular metabolism. Future prospects for research in this area are discussed.

Bahn, P. R.↗
NASA NTRS2019

Dynamic Modeling of Gaseous Multicomponent Trace Contaminant Adsorption

Activated carbon is a porous material in the Trace Contaminant Control (TCC) system that physically adsorbs volatile organic compounds (VOCs) generated within spacecraft and spacesuit environments. Several isotherm models exist to predict adsorption equilibria for processes involving multicomponent systems. This paper investigates the use of Ideal Adsorbed Solution Theory (IAST) for predicting multicomponent trace contaminant adsorption behavior using single-component isotherms based on potential theory. Developing simulations for experimental breakthrough curves will gauge the validity on the sizing and design of TCC architecture. Model results on predicting bed performance and roll-up effects are compared with available multicomponent test data.

Ideal Adsorbed Solution Theory (IAST)↗