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All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

Downwelling Far-Infrared Emission Spectra Measured by FIRST at Cerro Toco, Chile and Table Mountain Facility, CA

The Far-Infrared Spectroscopy of the Troposphere (FIRST) instrument is a fourier transform spectrometer developed to measure the far-infrared portion of the Earth's longwave spectrum. Specifically, the purpose is measurement of the important, yet under-investigated 100 to 1000 cm-1 band. Presented here are measurements made by FIRST at two successful deployments in a ground-based configuration to measure downwelling longwave radiation. The initial deployment was to Cerro Toco, Chile. FIRST operated from August to October, 2009 as part of the Radiative Heating in Underexplored Bands Campaign (RHUBC-II) campaign. After recalibration, FIRST was deployed to the Table Mountain Facility from August to October, 2012. Dry days for both campaigns were chosen for analysis ? 09/24/2009 and 10/19/2012. Also available from both deployments are coincident radiosonde temperature and water vapor vertical profiles used as inputs to radiance calculations performed by two platforms, the AER Line-by-Line Radiative Transform Model (using the AER line database), and a research platform, MRTA utilizing HITRAN 2012. Thus, we have three streams of data for the closure studies, and results of the comparisons are presented showing good agreement in the optically thick regions of 200-400 cm-1 and 600-800 cm-1. Differences between measured and coincident calculated spectra between 400 and 600 cm-1 are less than 10 mW/m^2/sr/cm-1. Uncertainties accounted for in this study include uncertainty from multiple detectors, water vapor, temperature, line strength and width as presented in HITRAN 2012, and due to internal heating caused by black bodies. The residuals fall within the root-sum-square envelope of the uncertainties.

J Mast↗
DOE OSTI2022

City-level impacts of building tune-ups: Findings from Seattle's building tune-ups program

Many U.S. cities are implementing policies to reduce greenhouse gas (GHG) emissions of their buildings. These range from building energy benchmarking and disclosure to building performance standards (BPS) that require buildings to meet specific targets of energy use or emissions. The City of Seattle adopted a climate action plan in 2013 that set a goal of zero net GHG emissions in the road transportation, buildings, and waste sectors by 2050, with a number of near and long term actions. Seattle implemented mandatory building tune-ups in 2016, applying to commercial buildings larger than 50,000 sqft. Building tune-ups1 involve assessment and implementation of operational and maintenance (O + M) improvements to achieve energy and water efficiency, such as changes to thermostat set points or adjusting lighting or irrigation schedules. Seattle's tune-ups program covered 27 such improvements in HVAC, lighting, domestic hot water, and envelope systems.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2014

Statistical studies based on simultaneous SiO and H{sub 2}O maser surveys toward evolved stars

Based on the simultaneous observational results of SiO and H{sub 2}O masers toward 401 evolved stars, we have performed statistical analyses. We find that the peak and integrated intensities of SiO masers are stronger than those of H{sub 2}O masers in both Mira variables and OH/IR stars at most optical phases. However, the relative intensity ratios of H{sub 2}O to SiO masers in OH/IR stars are larger than those in Mira variables. Moreover, the intensity ratios of H{sub 2}O to SiO masers are found to be increased around the optical phases from 0-0.4. The H{sub 2}O photon luminosities also tend to be more dependent on the optical phase compared with those of SiO masers. These facts suggest that H{sub 2}O masers are more sensitive to expanding the motion of circumstellar envelopes and also shock waves arising from the pulsations of the central star compared with SiO masers. This result may also be related to the differences in the maser location and pumping mechanism between H{sub 2}O and SiO masers. The full width at zero power of SiO masers in Mira variables shows similar values to those of OH/IR stars, while those of H{sub 2}O masers in OH/IR stars show larger values than those of Mira variables. These differences may originate from the different mass-loss rates and the different location of the two masers. The mean velocity shift of SiO and H{sub 2}O masers with respect to the stellar velocity was investigated as a function of optical phase. The velocity shift of the H{sub 2}O masers shows that the redshifted emission dominates during the phases from 0.3-0.6, while the blueshifted emission appears at phase 0.6 and coexists with the redshifted emission during other phases. These features show an associated pattern with the CO ΔV = 3 radial velocity curve, which exhibits a typical pulsation motion. On the other hand, the velocity shift of the SiO v = 2 maser shows slightly similar features to the H{sub 2}O maser, while that of SiO v = 1 does not show these similar features. Finally, the distributions of all 401 observed sources are investigated in the IRAS two-color diagram in relation to the late evolutionary processes of asymptotic giant branch stars.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1989

Turbine stage aerodynamics and heat transfer prediction

A numerical study of the aerodynamic and thermal environment associated with axial turbine stages is presented. Computations were performed using a modification of the unsteady NASA Ames viscous code, ROTOR1, and an improved version of the NASA Lewis steady inviscid cascade system MERIDL-TSONIC coupled with boundary layer codes BLAYER and STAN5. Two different turbine stages were analyzed: the first stage of the United Technologies Research Center Large Scale Rotating Rig (LSRR) and the first stage of the Space Shuttle Main Engine (SSME) high pressure fuel turbopump turbine. The time-averaged airfoil midspan pressure and heat transfer profiles were predicted for numerous thermal boundary conditions including adiabatic wall, prescribed surface temperature, and prescribed heat flux. Computed solutions are compared with each other and with experimental data in the case of the LSRR calculations. Modified ROTOR1 predictions of unsteady pressure envelopes and instantaneous contour plots are also presented for the SSME geometry. Relative merits of the two computational approaches are discussed.

Griffin, Lisa W.↗
NASA NTRS2014

The Meteoroid Fluence at Mars Due to Comet C/2013 A1 (Siding Spring)

Long-period comet C/2013 A1 (Siding Spring) will experience a close encounter with Mars on 2014 Oct 19. A collision between the comet and the planet has been ruled out, but the comet's coma may envelop Mars and its man-made satellites. By the time of the close encounter, five operational spacecraft will be present near Mars. Characterizing the coma is crucial for assessing the risk posed to these satellites by meteoroid impacts. We present an analytic model of cometary comae that describes the spatial and size distributions of cometary dust and meteoroids. This model correctly reproduces, to within an order of magnitude, the number of impacts recorded by Giotto near 1P/Halley [1] and by Stardust near comet 81P/Wild 2 [2]. Applied to Siding Spring, our model predicts a total particle fluence near Mars of 0.02 particles per square meter. In order to determine the degree to which Siding Spring's coma deviates from a sphere, we perform numerical simulations which take into account both gravitational effects and radiative forces. We take the entire dust component of the coma and tail continuum into account by simulating the ejection and evolution of dust particles from comet Siding Spring. The total number of particles simulated is essentially a free parameter and does not provide a check on the total fluence. Instead, these simulations illustrate the degree to which the coma of Siding Spring deviates from the perfect sphere described by our analytic model (see Figure). We conclude that our analytic model sacrifices less than an order of magnitude in accuracy by neglecting particle dynamics and radiation pressure and is thus adequate for order-of-magnitude fluence estimates. Comet properties may change unpredictably and therefore an analytic coma model that enables quick recalculation of the meteoroid fluence is highly desirable. NASA's Meteoroid Environment Office is monitoring comet Siding Spring and taking measurements of cometary brightness and dust production. We will discuss our coma model and nominal fluence taking the latest observations into account.

Moorhead, A.↗
NASA NTRS2005

On-Line Loss of Control Detection Using Wavelets

Wavelet transforms are used for on-line detection of aircraft loss of control. Wavelet transforms are compared with Fourier transform methods and shown to more rapidly detect changes in the vehicle dynamics. This faster response is due to a time window that decreases in length as the frequency increases. New wavelets are defined that further decrease the detection time by skewing the shape of the envelope. The wavelets are used for power spectrum and transfer function estimation. Smoothing is used to tradeoff the variance of the estimate with detection time. Wavelets are also used as front-end to the eigensystem reconstruction algorithm. Stability metrics are estimated from the frequency response and models, and it is these metrics that are used for loss of control detection. A Matlab toolbox was developed for post-processing simulation and flight data using the wavelet analysis methods. A subset of these methods was implemented in real time and named the Loss of Control Analysis Tool Set or LOCATS. A manual control experiment was conducted using a hardware-in-the-loop simulator for a large transport aircraft, in which the real time performance of LOCATS was demonstrated. The next step is to use these wavelet analysis tools for flight test support.

Brenner, Martin J.↗
DOE OSTI2022

Design, Construction, and Field Validation of a Blown-In Fiberglass Wall System in a Cold, Wet, and Windy Climate

In the Native Village of Tununak, located on Nelson Island in Southwest Alaska,buildings are exposed to wind-driven rain and snow throughout the year. The Cold Climate Housing Research Center (CCHRC) and Knauf Insulation partnered with the community in 2018 to design a residence for a public safety officer. Construction began in fall 2021 and is scheduled to conclude in summer 2022. The house will use integrated trusses with floor, attic, and wall cavities filled with blown-in fiberglass insulation. Hygrothermal models of the building envelope system demonstrate that the high ambient moisture load will wet the outer edges of the insulation annually regardless of the extent and integrity of exterior weather sealing measures; blown-in fiberglass is expected to be more resilient to this wetting than blown-in cellulose. To verify this, researchers will embed temperature, relative humidity, and moisture sensors in the two windward walls of the house to monitor the ability of the blown-in fiberglass insulation to dry out after wetting events that may have occurred during the transport of the insulation to the building site, storage of the insulation on site, construction process, or after installation in the wall. Sensors will remain in place for two years,documenting the wall's performance over time and verifying the design's potential for use in buildings located in climates where the chance for moisture damage is high. Here, we describe the wall system , design criteria, and the results from the hygrothermal modeling. We share details on the monitoring system's components and the planned management and analysis of data. Finally, we explain how the experiences and data from this project will inform future builds in similar locations.

building design↗
DOE OSTI2018

Lab-scale Development of a Hybrid Capture System with Advanced Membrane, Solvent system, and Process Integration

The objective of the project is to achieve lab-scale demonstration of a transformational hybrid membrane/solvent system for the capture of CO 2 from flue gas. A novel process integration scheme was proposed to overcome the low partial pressure of CO 2 present in flue gas. This scheme takes advantage of the potential synergies inherent in the membrane and solvent capture systems. The proposed hybrid technology replaces the second-stage membrane with a solvent capture process. The combustion air is used as a sweeping gas in the solvent stripper. This overall configuration has the major advantages of requiring much less air and eliminating the problems associated with oxygen slip in the membrane-based systems. Even more importantly, because of the presence of the air sweep in the stripper, much lower temperatures are required for solvent regeneration, which enables heat integration to the point that no process steam is required. This project was to perform lab-scale demonstration of Liquid Ion Solutions (LIS) transformational hybrid membrane/solvent system for post-combustion CO 2 capture while demonstrating significant progress toward achievement of the overall fossil energy performance goals of 90% CO 2 capture rate with 95% CO 2 purity at a cost of electricity 30% less than baseline capture approaches. This report is written chronologically based on budget periods. Each budget period discusses the work performed and its results. At the end of each budget period the milestone charts are provided to show the progress. This project was not able to meet its stated goals. The performances of the power plant equipped with the hybrid process and Baseline Case B12B were compared. The simulation results showed that the power plant equipped with hybrid CO2 capture process has an improved thermal efficiency of 33.4% compared to the Baseline Case B12B, which is 32.5%. However, the COE for the hybrid process is $146.3/MWh which is higher than the $142.8/MWh for Case B12B. If this process were to be applied as a retrofit, it may make sense to use this configuration as it does not require any change in an existing plant configuration and steam cycle. However, for a new powerplant the capital cost is higher than the Case B12B. On the membrane development side, we successfully showed that interfacially-controlled envelope (ICE) membranes work. The inclusion of surface modified nano-particles results in much higher gas diffusivities. The Gen-1 ICE membrane developed under this project showed exceptional improved permeability for CO 2 . However, we ran into major problems which were associated with the scalability and reproducibility of the poly(phosphozene) polymers. The issues with scale-up are and batch to batch variability is also discussed. At the end of this report we have provided our recommendations on materials development for better membrane materials and alluded to the use of much simpler chemistry while keeping the concept of ICE membrane intact. It is also clear that vacuum and compression equipment is costly. If a process which can eliminate the use of vacuum and compression equipment would significantly decrease the overall cost of capture. Some thoughts regarding such system is also provided in the outlook portion of this report.

20 FOSSIL-FUELED POWER PLANTS↗
NASA NTRS1985

Oblique wing ready for research aircraft

Performance features and possible design configurations for oblique wings which would lower the supersonic drag characteristics of fighter aircraft are described. The oblique shape reduces wave drag in proportion to the wing length, and can achieve reductions by factors of 4-16. Variable sweep would be accompanied by fuel pumping to maintain an acceptable center of gravity and tail loading. The lift forces remain balanced and thus remove fuselage loads considerations. Extra tail loading to handle longitudinal moments of center-of-lift shifts with variable sweep aircraft are also eliminated. However, oblique wings couple the roll, pitch and yaw axes and require digital controls to provide balancing forces. NASA has initiated a four phase design, construction and flight test program to examine the flight envelope of oblique wings on the F-8 aircraft.

Gregory, T.↗
DOE OSTI2025

Thermal performance and energy consumption validation of an occupied local government office building outfitted with ceiling tile phase change materials

Buildings present an opportunity for energy conservation and the modulation of peak energy demand through controlled Heating, Ventilation, and Air Conditioning (HVAC) energy use. The administrative and office building stock in the United States holds potential to achieve energy and demand savings through retrofits such as insulation, weatherization, and thermal energy storage. Specifically, there is a need to validate passive phase change material (PCM) applications in full scale in aging administrative buildings in the US to evaluate the energy benefits. Aim of this study was to conduct a whole building level thermal and energy validation of an operational building and explore an alternative method for evaluating energy efficiency. To accomplish this, the study employed PCMs in the drop ceiling and carry out an energy audit and on-site measurement of HVAC systems' energy demand and consumption. A full-scale EnergyPlus energy model, modeled by the authors, served as a baseline for evaluation. The results show that calibrated model's envelope temperature measures fall within the accepted errors. HVAC energy simulation results also fall within the accepted errors for monthly and hourly pre- and post- PCM retrofit electricity and natural gas data. The novelty of this study is that it employees energy scales per Heating Degree Hour and Cooling Degree Hour, in contrast to the commonly used Heating Degree Days and Cooling Degree Days as reported in the literature to analyze energy savings. These findings underscore the pivotal role of a calibrated model in assessing the efficacy of a singular energy measure, like a PCM-retrofitted ceiling, in an occupied office building.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2016

Nano-based PCMs for building energy efficiency

Thermal storage using phase change materials (PCMs) is seen as a viable method for improving the energy efficiency of buildings. PCMs have been used in building applications in various forms PCM slurries in heat exchangers, macro- or microencapsulated PCMs in building envelopes, bulk PCM for modulating photovoltaic temperatures, etc. In the last decade a new class of PCMs, called nano-enhanced PCM (or nanoPCM), has been extensively investigated with the goal of improving the heat transfer and thermal storage properties of PCMs. NanoPCMs can primarily be categorized as nano-encapsulated PCMs and nanoparticle-PCM composites. The former are nano-sized capsules in which the PCM forms the core and is surrounded by a high-conductivity membrane or shell. The latter consist of PCM supported within nanostructures or nanoparticles dispersed in PCMs. This article reviews the current state of nanoPCM synthesis and characterization of their heat transfer and thermal storage properties. Further, a critical review of nanoPCM applications and their potential energy benefits is performed. Nano-enhanced PCMs exhibit higher thermal conductivities than regular PCM. However, whether the higher conductivity is desirable in all applications and if the property enhancements are worth the cost and effort needed to create nanoPCMs are questions that still need to be answered.

nano-encapsulated PCM↗
DOE OSTI2014

Hydronic Heating Coil Versus Propane Furnace, Rehoboth Beach, Delaware (Fact Sheet)

Insight Homes constructed two houses in Rehoboth Beach, Delaware, with identical floor plans and thermal envelopes but different heating and domestic hot water (DHW) systems. Each house is 1,715-ft 2 with a single story, three bedrooms, two bathrooms, and the heating, ventilation, and air conditioning (HVAC) systems and ductwork located in conditioned crawlspaces. The standard house, which the builder offers as its standard production house, uses an air source heat pump (ASHP) with supplemental propane furnace heating. The Building America test house uses the same ASHP unit with supplemental heat provided by the DHW heater (a combined DHW and hydronic heating system, where the hydronic heating element is in the air handler). Both houses were occupied during the test period. Results indicate that efficiency of the two heating systems was not significantly different. Three issues dominate these results; lower system design performance resulting from the indoor refrigerant coil selected for the standard house, an incorrectly functioning defrost cycle in the standard house, and the low resolution of the natural gas monitoring equipment. The thermal comfort of both houses fell outside the ASHRAE Standard 55 heating range but was within the ACCA room-to-room temperature range when compared to the thermostat temperature. The monitored DHW draw schedules were input into EnergyPlus to evaluate the efficiency of the tankless hot water heater model using the two monitored profiles and the Building America House Simulation Protocols. The results indicate that the simulation is not significantly impacted by the draw profiles.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2022

Development and Validation of Algorithms That Analyze Communicating Thermostat Data to Identify Enclosure Retrofit Opportunities

Annual energy savings of up to $\$ 4$ to $\$ 5$ billion could be achieved nationwide through basic insulation and heating system retrofits of existing homes. However, current utility energy efficiency programs are costly and challenging to scale. Customer acquisition occurs primarily through energy bill mailers, mass media, and online advertising that lack specificity about home-specific retrofit opportunities, expected energy savings, and cost-effectiveness. Specific retrofit opportunities are identified via on-site home energy assessments (HEAs) that are inconvenient to homeowners, expensive, and of variable accuracy. We developed computational algorithms that automatically analyze communicating thermostat (CT) heating data that could be used to increase the customer uptake of insulation and air sealing energy conservation measures (ECMs) by identifying homes with the most significant retrofit opportunities, estimating post-retrofit energy savings, and formulating home-specific outreach. The algorithms are based on an extended second-order grey-box model that characterizes a building’s thermal response using lumped elements, coupled with an empirical model of infiltration that accounts for both wind and stack effects. The basic parameters of the model correspond to actual physical parameters of the home, i.e., the home’s overall R-value of and the building envelope ACH50. Unlike the conventional approach, which estimates model parameters based on the best fit to the observed time-dependent room temperature, our approach derives correlations between the daily heating system runtime and temperature difference (indoor-outdoor) that are more robust to data quality issues in real-world applications. We also used HEA data for algorithm development and validation. With the help of our utility partners, Eversource and National Grid, we obtained data sets for hundreds of Massachusetts homes. For each home, these data sets included three sets of information anonymized by the utility: (1) CT data (HVAC runtime, room temperature, and, for some vendors, outdoor temperature and wind speed) collected by the CT vendor (one of three) over a heating season, (2) HEA report performed by the HEA vendor (same vendor for all homes), (3) Monthly utility gas bills coincident with the CT data (3 to 24 per home, depending on availability). For some homes, we also obtained blower-door test results. Initially, we applied the algorithms developed to homes with a single CT and then extended them to homes with two CTs by using an equivalent home approach. Finally, we developed algorithms for prediction of energy savings and a methodology of comparing our predictions with those generated by HEAs. The main technical results indicate that we can reliably identify homes with insulation and/or air sealing retrofit opportunities and provide accurate savings predictions. Our hypothesis is that the algorithms could be applied to utility energy efficiency programs to identify homes that could realize significant energy savings from insulation and/or air sealing retrofits. This information could then be used to reach out to those homes with highly customized outreach, thereby delivering increased program energy savings and cost-effectiveness. This would: Significantly increase the uptake rate of on-site HEAs, and Significantly increase the fraction of HEAs resulting in ECM implementation. To test these hypotheses, we designed and conducted a randomized controlled trial (RCT). The RCT results suggest that personal messaging leads to a two- to five-fold increase in the HEA uptake rate.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2019

Effect of the concentration ratio on energetic and exergetic performance of concentrating solar collectors with integrated transparent insulation materials

The effect of the concentration ratio on the performance of parabolic trough and central receiver collectors with integrated Transparent Insulation Materials (TIMs) is analyzed in this work. A model based on optical, energy, and exergy analyses is developed to determine thermal and second law efficiencies of concentrated solar collectors as a function of the absorber temperature and concentration ratio. The results are compared with the respective traditional collector configurations without TIM. In general, high concentration ratios are fundamental to maintain high efficiencies. The incorporation of a TIM into concentrated solar collectors leads to higher thermal efficiencies at high operating temperatures even at low concentration ratios. An equivalent second law efficiency to that of the reference collector configuration can be achieved at lower concentration ratios by incorporating a TIM in parabolic trough or a TIM and a glass envelope in central receiver collectors. As a result, the idea of using a TIM deserves further exploration as it seems to be a promising alternative that contributes to a more efficient and cost-effective technology.

14 SOLAR ENERGY↗
DOE OSTI2024

Energetic and Spectroscopic Properties of Astrophysically Relevant MgC 4 H Radicals Using High-Level Ab Initio Calculations

Considering the importance of magnesium-bearing hydrocarbon molecules (MgC n H; n = 2, 4, and 6) in the carbon-rich circumstellar envelopes (e.g., IRC+10216), a total of 28 constitutional isomers of MgC 4 H have been theoretically investigated using density functional theory (DFT) and coupled-cluster methods. The zero-point vibrational energy corrected relative energies at the ROCCSD(T)/cc-pCVTZ level of theory reveal that the linear isomer, 1-magnesapent-2,4-diyn-1-yl (1, 2 Σ + ), is the global minimum geometry on the MgC 4 H potential energy surface. The latter has been detected both in the laboratory and in the evolved carbon star, IRC+10216. The calculated spectroscopic data for 1 match well with the experimental observations (error ~ 0.78%) which validates our theoretical methodology. Plausible isomerization processes happening among different isomers are examined using DFT and coupled-cluster methods. CASPT2 calculations have been performed for a few isomers exhibiting multireference characteristics. The second most stable isomer, 1-ethynyl-1λ 3 -magnesacycloprop-2-ene-2,3-diyl (2, 2 A 1 , μ = 2.54 D), is 146 kJ mol –1 higher in energy than 1 and possibly the next promising candidate to be detected in the laboratory or in the interstellar medium in future.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS2008

An Integrated Approach to Damage Accommodation in Flight Control

In this paper we present an integrated approach to in-flight damage accommodation in flight control. The approach is based on Multiple Models, Switching and Tuning (MMST), and consists of three steps: In the first step the main objective is to acquire a realistic aircraft damage model. Modeling of in-flight damage is a highly complex problem since there is a large number of issues that need to be addressed. One of the most important one is that there is strong coupling between structural dynamics, aerodynamics, and flight control. These effects cannot be studied separately due to this coupling. Once a realistic damage model is available, in the second step a large number of models corresponding to different damage cases are generated. One possibility is to generate many linear models and interpolate between them to cover a large portion of the flight envelope. Once these models have been generated, we will implement a recently developed-Model Set Reduction (MSR) technique. The technique is based on parameterizing damage in terms of uncertain parameters, and uses concepts from robust control theory to arrive at a small number of "centered" models such that the controllers corresponding to these models assure desired stability and robustness properties over a subset in the parametric space. By devising a suitable model placement strategy, the entire parametric set is covered with a relatively small number of models and controllers. The third step consists of designing a Multiple Models, Switching and Tuning (MMST) strategy for estimating the current operating regime (damage case) of the aircraft, and switching to the corresponding controller to achieve effective damage accommodation and the desired performance. In the paper present a comprehensive approach to damage accommodation using Model Set Design,MMST, and Variable Structure compensation for coupling nonlinearities. The approach was evaluated on a model of F/A-18 aircraft dynamics under control effector damage, augmented by nonlinear cross-coupling terms and a structural dynamics model. The proposed approach achieved excellent performance under severe damage effects.

Boskovic, Jovan D.↗
NASA NTRSDate not supplied

Current Test Capabilities of NASA Langley’s Arc-Heated Scramjet Test Facility

The Arc-Heated Scramjet Test Facility at NASA Langley Research Center has demonstrated itself repeatedly as a key contributor to fundamental hypersonic research and scramjet engine technology development in the Mach 4.7 to 8 range. Since its inception in the 1970’s, the facility has hosted numerous scramjet engine configurations that explored the performance and operability of airframe-integrated hydrogen-fueled scramjet flow path concepts, successfully maturing both analysis tools and design technique and methodology for hypersonic propulsion. Contributions to major programs include extensive tests of the hydrogen-fueled NASP and Hyper-X scramjet engines, and the hydrocarbon-fueled HIFiRE Flight 2 scramjet flow path, in addition to fundamental in-house research. The facility capabilities have expanded to include direct-connect flow path support, gaseous hydrocarbon fuels, dynamic trajectory simulation and extension of flight simulation down to Mach 2.2. The low-Mach upgrades include increased air flow rate and controls capability and two new low-Mach nozzles (Mach 2.2 and 3.5). The facility recently completed verification of the new operational range through successful envelope expansion tests with the Mach 2.2 nozzle. With these new modifications, the operating envelope for the facility is now Mach 2.2 – 8.0(+), with a demonstrated dynamic pressure simulation of 2000 psf at the low end, and margin available for even more. Lastly, a continuous run time of over 5 minutes has been demonstrated, indicating that run time is limited only by test hardware or back-pressure requirements. This paper will provide a detailed description of these previously unreported upgrades and expanded simulation capabilities.

Hypersonic↗
NASA NTRS1979

Experimental study of the flight envelope and research of safety requirements for hang-gliders

The flight mechanic computations were computed, providing both the flight envelopes with all sorts of limits and a fairly precise idea of the influence of several parameters, such as pilot's weight, wing settings, aeroelasticity, etc... The particular problem of luffing dives was thoroughly analyzed, and two kinds of causes were exhibited in both the rules of luffing and aeroelastic effects. The general analysis of longitudinal stability showed a strong link with fabric tension, as expected through Nielsen's and Twaites' theory. Fabric tension strongly depending upon aeroelasticity, that parameter was found to be the most effective design one for positive stability. Lateral stability was found to be very similar in all gliders except perhaps the cylindro-conical. The loss of stability happens in roll at low angle of attack, whereas it happens in yaw at high angle. Turning performance was a bit suprising, with a common maximum value of approximately 55 deg of bank angle for a steady turn.

Laburthe, C.↗