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At least 361 records · Page 20
All sourcesNASA NTRSDOE OSTI
NASA NTRS1984

Simulator study of flight characteristics of several large, dissimilar, cargo transport airplanes during approach and landing

A six-degree-of-freedom, ground based simulator study is conducted to evaluate the low-speed flight characteristics of four dissimilar cargo transport airplanes. These characteristics are compared with those of a large, present-day (reference) transport configuration similar to the Lockheed C-5A airplane. The four very large transport concepts evaluated consist of single-fuselage, twin-fuselage, triple-fuselage, and span-loader configurations. The primary piloting task is the approach and landing operation. The results of his study indicate that all four concepts evaluated have unsatisfactory longitudinal and lateral directional low speed flight characteristics and that considerable stability and control augmentation would be required to improve these characteristics (handling qualities) to a satisfactory level. Through the use of rate command/attitude hold augmentation in the pitch and roll axes, and the use of several turn-coordination features, the handling qualities of all four large transports simulated are improved appreciably.

Grantham, W. D.↗
NASA NTRS2023

Highly Resolved Mapping of NO 2 Vertical Column Densities From GeoTASO Measurements Over a Megacity and Industrial Area During the KORUS-AQ Campaign

The Korea–United States Air Quality (KORUS-AQ) campaign is a joint study between the United States National Aeronautics and Space Administration (NASA) and the South Korea National Institute of Environmental Research (NIER) to monitor megacity and transboundary air pollution around the Korean Peninsula using airborne and ground-based measurements. Here, tropospheric nitrogen dioxide (NO 2 ) slant column density (SCD) measurements were retrieved from Geostationary Trace and Aerosol Sensor Optimization (GeoTASO) L1B data during the KORUS-AQ campaign (2 May to 10 June 2016). The retrieved SCDs were converted to tropospheric vertical column densities using the air mass factor (AMF) obtained from a radiative transfer calculation with trace gas profiles and aerosol property inputs simulated with the Community Multiscale Air Quality (CMAQ) model and surface reflectance data obtained from the Moderate Resolution Imaging Spectroradiometer (MODIS). For the first time, we examine highly resolved (250 m × 250 m resolution) tropospheric NO 2 over the Seoul and Busan metropolitan regions and the industrial region of Anmyeon. We reveal that the maximum NO 2 vertical column densities (VCDs) were 4.94×10 16 and 1.46×10 17 molec. cm −2 at 09:00 and 15:00 LT over Seoul, respectively, 6.86×10 16 and 4.89×10 16 molec. cm −2 in the morning and afternoon over Busan, respectively, and 1.64×10 16 molec. cm −2 over Anmyeon. The VCDs retrieved from the GeoTASO airborne instrument were correlated with those obtained from the Ozone Monitoring Instrument (OMI) (r=0.48), NASA's Pandora Spectrometer System (r=0.91), and NO 2 mixing ratios obtained from in situ measurements (r=0.07 in the morning, r=0.26 in the afternoon over the Seoul, and r>0.56 over Busan). Based on our results, GeoTASO is useful for identifying NO 2 hotspots and their spatial distribution in highly populated cities and industrial areas.

Gyo-Hwang Choo↗
NASA NTRSDate not supplied

Changes in Plants Developed from Imbibed Seeds Irradiated by Simulated Solar Particle Events

One of the major concerns for long-term exploration missions beyond the Earth’s magnetosphere is radiation risk primarily from solar particle events (SPEs) and galactic cosmic rays (GCRs). With the goal of manned Mars exploration, the production of fresh food during long duration space missions may provide nutritional supplementation and benefit astronauts’ behavioral health. However, the effects of space radiation on plants and plant propagules have not been sufficiently investigated and characterized. In this study, we evaluated the effect of simulated GCRs on dry seeds of mizuna mustard, ‘Outredgeous’ red romaine lettuce, and ‘Red Robin’ dwarf tomato. Seeds were exposed to various doses of simulated GCRs (0, 40, and 80 cGy), either acutely or at a low dose rate (LDR), using the NASA Space Radiation Laboratory (NSRL) facility at Brookhaven National Lab (BNL). Control and irradiated seeds were planted and maintained under space-vehicle relevant controlled environment conditions. Plant/fruit morphometrics and edible fresh mass were measured. In addition, nutrient analyses were performed for both mizuna and ripe tomatoe fruit. Seedlings from irradiated seeds (both 40 cGy and 80 cGy) showed significant changes in cotyledon development, but not in root length or morphology. Interestingly, significant changes in vitamin content were found in mizuna grown from 80 cGy (LDR) irradiated seeds. In addition, 80 cGy (LDR) simulated GCRs significantly affected lettuce and tomato seed quality, delayed tomato fruiting, and reduced the total yield of tomato. Generally, compared to 80 cGy, 40 cGy (LDR) of simulated GCRs displayed some impacts to the seeds and seedlings, but to a much lesser degree. (This study was supported by NASA Human Research Program.)

J.T. Richards↗
NASA NTRS2012

SO2 over Central China: Measurements, Numerical Simulations and the Tropospheric Sulfur Budget

SO2 in central China was measured in situ from an aircraft and remotely using the Ozone Monitoring Instrument (OMI) from the Aura satellite; results were used to develop a numerical tool for evaluating the tropospheric sulfur budget - sources, sinks, transformation and transport. In April 2008, measured ambient SO2 concentrations decreased from approx.7 ppbv near the surface to approx. 1 ppbv at 1800 m altitude (an effective scale height of approx.800 m), but distinct SO2 plumes were observed between 1800 and 4500 m, the aircraft's ceiling. These free tropospheric plumes play a major role in the export of SO2 and in the accuracy of OMI retrievals. The mean SO2 column contents from aircraft measurements (0.73 DU, Dobson Units) and operational OMI SO2 products (0.63+/-0.26 DU) were close. The OMI retrievals were well correlated with in situ measurements (r = 0.84), but showed low bias (slope = 0.54). A new OMI retrieval algorithm was tested and showed improved agreement and bias (r = 0.87, slope = 0.86). The Community Multiscale Air Quality (CMAQ) model was used to simulate sulfur chemistry, exhibiting reasonable agreement (r = 0.62, slope = 1.33) with in situ SO2 columns. The mean CMAQ SO2 loading over central and eastern China was 54 kT, approx.30% more than the estimate from OMI SO2 products, 42 kT. These numerical simulations, constrained by observations, indicate that ",50% (35 to 61 %) of the anthropogenic sulfur emissions were transported downwind, and the overall lifetime of tropospheric SO2 was 38+/-7 h.

He, Hao↗
NASA NTRS2019

Analysis of A Severe Dust Storm and Its Impact on Air Quality Conditions Using Wrf-Chem Modeling, Satellite Imagery, and Ground Observations

This study presents a comprehensive analysis of an extreme dust event recorded in the Arabian Peninsula and the United Arab Emirates (UAE) between 31 March and 3 April 2015. Simulations of the dust event with the Weather Research and Forecasting model coupled with the Chemistry module (WRF-Chem) were analyzed and verified using MSG-SEVIRI imagery and aerosol optical depth (AOD) from the recent 1-km Multi-Angle Implementation of Atmospheric Correction (MAIAC) algorithm for MODIS Terra/Aqua. Data from the National Centers for Atmospheric Prediction/National Center for Atmospheric Research (NCEP/NCAR) and the upper-air radiosonde observations were used to understand the synoptic of the event. In addition, the impact of the event on atmospheric and air quality conditions is investigated. The Air Quality Index (AQI) was calculated prior, during, and after the event to assess the degradation of air quality conditions. Simulated temperature, relative humidity, wind speed, and surface radiation were compared to observations at six monitoring stations in the UAE giving R2 values of 0.84, 0.63, 0.60, and 0.84, respectively. From 1 to 2 April 2015, both observations and simulations showed an average drop in temperature from 33 to 26 °C and radiance reduction from about 950 to 520 Wm−2. The AOD modeled by WRF-Chem showed a good correlation with Aerosol Robotic Network (AERONET) measurements in the UAE with R2 of 0.83. The AQI over the UAE reached hazardous levels during the peak of the dust event before rapidly decreasing to moderate–good air quality levels. This work is the first attempt to demonstrate the potential of using WRF-Chem to estimate AQI over the UAE along with two satellite products (MODIS-MAIAC and MSG-SEVIRI) for dust detection and tracking.

dust storm↗
NASA NTRS1994

Piloted simulation study of two tilt-wing flap control concepts, phase 2

A two phase piloted simulation study has been conducted in the Ames Vertical Motion Simulator to investigate alternative wing and flap controls for tilt-wing aircraft. This report documents the flying qualities results and findings of the second phase of the piloted simulation study and describes the simulated tilt-wing aircraft, the flap control concepts, the experiment design and the evaluation tasks. The initial phase of the study compared the flying qualities of both a conventional programmed flap and an innovative geared flap. The second phase of the study introduced an alternate method of pilot control for the geared flap and further studied the flying qualities of the programmed flap and two geared flap configurations. In general, the pilot ratings showed little variation between the programmed flap and the geared flap control concepts. Some differences between the two control concepts were noticed and are discussed in this report. The geared flap configurations had very similar results. Although the geared flap concept has the potential to reduce or eliminate the pitch control power requirements from a tail rotor or a tail thruster at low speeds and in hover, the results did not show reduced tail thruster pitch control power usage with the geared flap configurations compared to the programmed flap configuration. The addition of pitch attitude stabilization in the second phase of simulation study greatly enhanced the aircraft flying qualities compared to the first phase.

Birckelbaw, Lourdes G.↗
NASA NTRS1984

Simulator evaluation of a remotely piloted vehicle lateral landing task using a visual display

A simulator evaluation of a remotely piloted research vehicle was conducted at NASA Ames Research Center's Dryden Flight Research Facility to determine the utility of a visual display when studying the influence of changes in the lateral stick gearing gains during landing approaches. The test vehicle used in this study was a highly maneuverable aircraft technology (HiMAT) aircraft, which is a 0.44 scale version of an envisioned small, single seat fighter airplane. Handling qualities ratings and comments obtained from pilots using a simulated visual display of a runway scene and a simulated instrument landing system (ILS) display were compared with the results of actual flight tests. The visual display was found to provide an adequate representation of the test vehicle in a visual landing approach, and it improved the roll response cues provided to the pilot. The handling qualities ratings and comments for flight and simulation visual landing approaches correlated well. The ILS simulation results showed reduced correlation compared with the flight results for ILS approaches. Handling qualities criteria for remotely piloted research vehicles are also discussed in this paper.

Sarrafian, S. K.↗
NASA NTRS1984

Simulator evaluation of a remotely piloted vehicle lateral landing task using a visual display

A simulator evaluation of a remotely piloted research vehicle was conducted at NASA Ames Research Center's Dryden Flight Research Facility to determine the utility of a visual display when studying the influence of changes in the lateral-stick gearing gains during landing approaches. The test vehicle used in this study was a highly maneuverable aircraft technology (HiMAT) aircraft, which is a 0.44-scale version of an envisioned small, single-seat fighter airplane. Handling qualities ratings and comments obtained from pilots using a simulated visual display of a runway scene and a simulated instrument landing system (ILS) display were compared with the results of actual flight tests. The visual display was found to provide an adequate representation of the test vehicle in a visual landing approach, and it improved the roll response cues provided to the pilot. The handling qualities ratings and comments for flight and simulation visual landing approaches correlated well. The ILS simulation results showed reduced correlation compared with the flight results for ILS approaches. Handling qualities criteria for remotely piloted research vehicles are also discussed in this paper.

Sarrafian, S. K.↗
NASA NTRS1982

Establishment of a rotor model basis

Radial-dimension computations in the RSRA's blade-element model are modified for both the acquisition of extensive baseline data and for real-time simulation use. The baseline data, which are for the evaluation of model changes, use very small increments and are of high quality. The modifications to the real-time simulation model are for accuracy improvement, especially when a minimal number of blade segments is required for real-time synchronization. An accurate technique for handling tip loss in discrete blade models is developed. The mathematical consistency and convergence properties of summation algorithms for blade forces and moments are examined and generalized integration coefficients are applied to equal-annuli midpoint spacing. Rotor conditions identified as 'constrained' and 'balanced' are used and the propagation of error is analyzed.

Mcfarland, R. E.↗
NASA NTRS2008

Initial Investigation of Reaction Control System Design on Spacecraft Handling Qualities for Earth Orbit Docking

A program of research, development, test, and evaluation is planned for the development of Spacecraft Handling Qualities guidelines. In this first experiment, the effects of Reaction Control System design characteristics and rotational control laws were evaluated during simulated proximity operations and docking. Also, the influence of piloting demands resulting from varying closure rates was assessed. The pilot-in-the-loop simulation results showed that significantly different spacecraft handling qualities result from the design of the Reaction Control System. In particular, cross-coupling between translational and rotational motions significantly affected handling qualities as reflected by Cooper-Harper pilot ratings and pilot workload, as reflected by Task-Load Index ratings. This influence is masked but only slightly by the rotational control system mode. While rotational control augmentation using Rate Command Attitude Hold can reduce the workload (principally, physical workload) created by cross-coupling, the handling qualities are not significantly improved. The attitude and rate deadbands of the RCAH introduced significant mental workload and control compensation to evaluate when deadband firings would occur, assess their impact on docking performance, and apply control inputs to mitigate that impact.

Bailey, Randall E.↗
NASA NTRS1974

Video requirements for remote medical diagnosis

Minimal television system requirements for medical telediagnosis were studied. The experiment was conducted with the aid of a simulated telemedicine system. The first step involved making high quality videotape recordings of actual medical examinations conducted by a skilled nurse under the direction of a physician watching on closed circuit television. These recordings formed the baseline for the study. Next, these videotape recordings were electronically degraded to simulate television systems of less than broadcast quality. Finally, the baseline and degraded video recordings were shown (via a statistically randomized procedure) to a large number of physicians who attempted to reach a correct medical diagnosis and to visually recognize key physical signs for each patient. By careful scoring and analysis of the results of these viewings, the pictorial and diagnostic limitations as a function of technical video characteristics were to be defined.

Davis, J. G.↗
NASA NTRS1993

Design of a flight control system for a highly maneuverable aircraft using mu synthesis

This paper presents a methodology for the design of longitudinal controllers for high performance aircraft operating over large ranges of angle of attack. The technique used for controller design is structured singular value or mu synthesis. The controller is designed to minimize the weighted H-infinity norm of the error between the aircraft response and the desired handling quality specifications without saturating the control actuators. The mu synthesis procedure ensures that the stability and performance of the aircraft is robust to parameter variations and modeling uncertainties included in the design model. Nonlinear simulations demonstrate that the controller satisfies handling quality requirements and provides excellent tracking of pilot inputs over a wide range of transient angles of attack and Mach number.

Reiner, Jacob↗
NASA NTRS1998

Development of a Simulation Capability for the Space Station Active Rack Isolation System

To realize quality microgravity science on the International Space Station, many microgravity facilities will utilize the Active Rack Isolation System (ARIS). Simulation capabilities for ARIS will be needed to predict the microgravity environment. This paper discusses the development of a simulation model for use in predicting the performance of the ARIS in attenuating disturbances with frequency content between 0.01 Hz and 10 Hz. The derivation of the model utilizes an energy-based approach. The complete simulation includes the dynamic model of the ISPR integrated with the model for the ARIS controller so that the entire closed-loop system is simulated. Preliminary performance predictions are made for the ARIS in attenuating both off-board disturbances as well as disturbances from hardware mounted onboard the microgravity facility. These predictions suggest that the ARIS does eliminate resonant behavior detrimental to microgravity experimentation. A limited comparison is made between the simulation predictions of ARIS attenuation of off-board disturbances and results from the ARIS flight test. These comparisons show promise, but further tuning of the simulation is needed.

Johnson, Terry L.↗
NASA NTRS1977

LANDSAT-D thematic mapper simulation using aircraft multispectral scanner data

A simulation of imagery from the upcoming LANDSAT-D thematic mapper was accomplished by using selected channels of 24-channels aircraft multispectral scanner data. The purpose was to simulate thematic mapper 30-meter resolution imagery and compare its spectral quality with the original aircraft MSS data and determine changes in thematic classification accuracy for the simulated imagery. The original resolution of approximately 7.5 meters IFOV and simulated resolution of 15, 30, and 60 meters were used to indicate the trend of spectral quality and classification accuracy. The study was based in a 6.5 square kilometer area of urban Los Angeles having a diversity of land use.

Clark, J.↗
NASA NTRSDate not supplied

Training the Powered-Lift Evaluation Pilot

This poster describes a project to prepare pilots for a study assessing novel aircraft automation concepts for electric Vertical Takeoff and Landing (eVTOL) aircraft using NASA’s Vertical Motion Simulator (VMS). By exploring the operational and learning challenges related to transitioning between forward flight and vertical landing, we seek to establish baselines of pilot workload and aircraft handling qualities across varying atmospheric conditions and automation states. The simulated eVTOL design differentiates flight control allocations as a function of airspeed across four speed ranges as the vehicle transitions between fully thrust-borne lift and wing-borne lift. As speed increases, side stick controls command: translational ground speeds, vertical and lateral acceleration, vertical rate, vertical flight path angle, and bank angle. This novel approach to flight control allocation creates a significant learning challenge for pilots. Since initial eVTOL aircraft may have limitations on hover capabilities, automation and flight guidance cues also vary with airspeed to provide efficient landing profiles while still providing cues suitable for cruise flight. The NASA team prepared the study pilots to follow these flight guidance cues along curved Required Navigation Performance (RNP) approaches and along 6o and 12o glide paths to energy-efficient assistive-hover landing and goarounds. The pre-VMS preparation sought to prepare pilots from diverse levels of experience and background. To do this, NASA researchers designed and developed a fixed-based, large field-ofview simulator with terrain, structures, and air traffic. With one day of combined classroom learning and skill development in the fixedbase simulator, pilots were largely able to fly the simulated eVTOL in the VMS with sufficient mastery to provide handling quality assessments using the Cooper-Harper Handling Qualities Rating and workload assessments through the Bedford Workload Scale.

AAM↗
NASA NTRS1980

Conceptual design study for an advanced cab and visual system, volume 1

A conceptual design study was conducted to define requirements for an advanced cab and visual system. The rotorcraft system integration simulator is for engineering studies in the area of mission associated vehicle handling qualities. Principally a technology survey and assessment of existing and proposed simulator visual display systems, image generation systems, modular cab designs, and simulator control station designs were performed and are discussed. State of the art survey data were used to synthesize a set of preliminary visual display system concepts of which five candidate display configurations were selected for further evaluation. Basic display concepts incorporated in these configurations included: real image projection, using either periscopes, fiber optic bundles, or scanned laser optics; and virtual imaging with helmet mounted displays. These display concepts were integrated in the study with a simulator cab concept employing a modular base for aircraft controls, crew seating, and instrumentation (or other) displays. A simple concept to induce vibration in the various modules was developed and is described. Results of evaluations and trade offs related to the candidate system concepts are given, along with a suggested weighting scheme for numerically comparing visual system performance characteristics.

Rue, R. J.↗
NASA NTRS1971

A progress report on the development of an augmentor wing jet STOL research aircraft.

The development of the aircraft has progressed to the point where the design of the modifications to the de Havilland C-8A Buffalo is complete and the engines are being tested. The predicted performance shows that the aircraft will be able to take off and land in less than 1500 ft. Simulation studies indicate that the handling qualities of the aircraft, with stability augmentation, will be acceptable for STOL research missions. Special techniques were required, however, for flight path control and transition from cruise to landing configuration .

Quigley, H. C.↗
NASA NTRS1971

Protective coatings for columbium applied in the field.

The various aspects of field repair of columbium alloy panels with protective coatings designed as part of the Space Shuttle thermal protection system are examined. The field repair of the coatings is accomplished by employing ceramic cement repairs, and reapplying the fused slurry silicide coating. Techniques are described which improve the practicality of these repairs by employing torch heating. The repair coating quality is demonstrated by testing which simulates flight temperature, pressure, stress and acoustic vibration conditions as a function of time. Conclusions on the present status of field repair coatings are presented and recommendations are given for appropriate future activities relative to the use on an operational Space Shuttle system.

Carter, J.↗