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NASA NTRSDate not supplied

An Overview of the NASA ADM-Aeolus Cal/Val Test Flight Campaign

Lidars are uniquely capable of collecting high precision and high spatio-temporal observations that have been used for atmospheric process studies from the ground, aircraft, and space for over 30 years. The Atmospheric Dynamics Mission Aeolus (ADM-Aeolus), the first-ever spaceborne Doppler wind lidar, was developed by the European Space Agency and launched in August 2018. The ADM-Aeolus Atmospheric Laser Doppler Instrument (ALADIN) observes profiles of the component of the wind vector and aerosol optical properties along the instrument’s line-of-sight direction on a global scale. Two airborne lidar systems have been developed at NASA Langley Research Center in recent years that collect measurements in support of several NASA Earth Science Division focus areas. The Doppler Aerosol WiNd (DAWN) lidar measures vertical profiles of horizontal wind speed and direction. The High Altitude Lidar Observatory (HALO) measure high resolution profiles of atmospheric water vapor (WV) and aerosol and cloud optical properties. Though new space-based missions with advanced capabilities such as Aeolus are continuously being conceived and developed, there are limitations in terms of spatial and vertical detail and measurement precision that can be accomplished from space, thus airborne remote sensing observations like those from DAWN and HALO are required to fill these observational gaps as well as to calibrate and validate space-based measurements. Over a two-week period in April 2019 during their Aeolus Cal/Val Test Flight campaign, NASA conducted five research flights over the Eastern Pacific Ocean with the DC-8 aircraft to 1) demonstrate the DAWN Doppler wind lidar, HALO high spectral resolution lidar aerosol/cloud measurement and differential absorption lidar WV measurement capabilities across a range of atmospheric conditions, 2) demonstrate Aeolus Cal/Val flight strategies and compare DAWN and HALO measurements with Aeolus to gain an initial perspective of Aeolus performance, and 3) demonstrate how atmospheric dynamic processes can be resolved and better understood through simultaneous observations of wind, WV, and aerosol profile observations, coupled with numerical model and other remote sensing observations. This paper provides a brief description of the DAWN and HALO instruments, discusses the synergistic observations collected across a wide range of atmospheric conditions sampled during the DC-8 flights, and a summary of the validation of DAWN, HALO, and Aeolus observations and comparisons.

Kristopher M. Bedka↗
NASA NTRS2024

X-Plane Knowledge Capture Workshop Summary Report

The history of experimental aircraft research and development at the National Aeronautics and Space Administration (NASA) provides a large body of work for current and future team members to learn from and apply. NASA values the knowledge it gains from all the research it performs and desires to have that knowledge grow with each new project, incrementally adding to the collective knowledge base. To support this knowledge growth and sharing, in May 2019, NASA convened over 60 engineers; researchers; and other personnel (internal and external to NASA) for the X-plane1 Knowledge Capture Workshop to discuss their over 50-years’ worth of experiences in developing, operating, and managing experimental aircraft. Over the course of a two-day workshop, the group not only focused, primarily, on current X-plane development but also discussed a wide range of topics about experimental aircraft and flight research. In addition to the discussions, senior NASA aeronautics leaders shared their personal lessons learned with the workshop audience. Broadly, these discussions centered around the topics of organizational and cultural practices, the project lifecycle, flight, and risk and safety. Many of the observations offered by participants are applicable to other NASA team-based projects, demonstrating the value in sharing lessons learned and best practices across projects regardless of their research focus. To share the most valuable lessons learned as broadly as possible, a summary of these discussions has been compiled into the following report. These discussions are mostly included in their entirety, with some light editing for clarity and privacy. NASA is sharing this knowledge internally and making it available to the public in hopes that others can learn from the experimental aircraft challenges and successes at NASA. Note: this document represents the perspectives, experiences, and opinions of others but does not necessarily represent the official view of NASA.

Steven R Hirshorn↗
NASA NTRSDate not supplied

Cryogenic Extension of NASA Species Polynomials Using Hydrogen and Oxygen at Stoichiometry

NASA has been conducting research in Rotating Detonation Rocket Engines (RDREs) for several years. A recent test at the Marshall Spaceflight Center has successfully shown operation of a RDRE that ran for 251 seconds which had combustion chamber cryogenic inlet conditions [1]. However, an overall pressure gain was not observed in the performance of the engine. Such an indication could mean an optimal chamber design is yet to be discovered. Such a design could significantly reduce parasitic pressure loses and improve overall engine efficiency beyond that of conventional rockets. To investigate different chamber configurations, new CFD capability is needed to accurately capture cryogenic thermophysical and transport property data. Such an effort is currently part of NASA’s Early Career Initiative (ECI) program. This paper focuses on the thermophysical property mixture model approach that makes use of NASA’s polynomial fits of species and another cryogenic model chosen from NIST’s Refprop program. Presented in this paper are results of a 1D denotation CFD simulation of stoichiometric Hydrogen and Oxygen mixture at a cryogenic upstream condition.

Combustion↗
NASA NTRS1994

Vista/F-16 Multi-Axis Thrust Vectoring (MATV) control law design and evaluation

For the Multi-Axis Thrust Vectoring (MATV) program, a new control law was developed using multi-axis thrust vectoring to augment the aircraft's aerodynamic control power to provide maneuverability above the normal F-16 angle of attack limit. The control law architecture was developed using Lockheed Fort Worth's offline and piloted simulation capabilities. The final flight control laws were used in flight test to demonstrate tactical benefits gained by using thrust vectoring in air-to-air combat. Differences between the simulator aerodynamics data base and the actual aircraft aerodynamics led to significantly different lateral-directional flying qualities during the flight test program than those identified during piloted simulation. A 'dial-a-gain' flight test control law update was performed in the middle of the flight test program. This approach allowed for inflight optimization of the aircraft's flying qualities. While this approach is not preferred over updating the simulator aerodynamic data base and then updating the control laws, the final selected gain set did provide adequate lateral-directional flying qualities over the MATV flight envelope. The resulting handling qualities and the departure resistance of the aircraft allowed the 422nd_squadron pilots to focus entirely on evaluating the aircraft's tactical utility.

Zwerneman, W. D.↗
NASA NTRS2009

Extravehicular Activity Testing in Analog Environments: Evaluating the Effects of Center of Gravity and Environment on Human Performance

The EVA Physiology, Systems and Performance (EPSP) Project is performing tests in different analog environments to understand human performance during Extravehicular Activity (EVA) with the aim of developing more safe and efficient systems for lunar exploration missions and the Constellation Program. The project is characterizing human EVA performance in studies using several test beds, including the underwater NASA Extreme Environment Mission Operations (NEEMO) and Neutral Buoyancy Laboratory (NBL) facilities, JSC fs Partial Gravity Simulator (POGO), and the NASA Reduced Gravity Office (RGO) parabolic flight aircraft. Using these varied testing environments, NASA can gain a more complete understanding of human performance issues related to EVA and the limitations of each testing environment. Tests are focused on identifying and understanding the EVA system factors that affect human performance such as center of gravity (CG), inertial mass, ground reaction forces (GRF), suit weight, and suit pressure. The test results will lead to the development of lunar EVA systems operations concepts and design requirements that optimize human performance and exploration capabilities. METHODS: Tests were conducted in the NBL and during NEEMO missions in the NOAA Aquarius Habitat. A reconfigurable back pack with repositionable mass was used to simulate Perfect, Low, Forward, High, Aft and NASA Baseline CG locations. Subjects performed simulated exploration tasks that included ambulation, kneel and recovery, rock pick-up, and shoveling. Testing using POGO, that simulates partial gravity via pneumatic weight offload system and a similar reconfigurable rig, is underway for a subset of the same tasks. Additionally, test trials are being performed on the RGO parabolic flight aircraft. Subject performance was assessed using a modified Cooper-Harper scale to assess operator compensation required to achieve desired performance. All CG locations are based on the assumption of a standardized 6 ft 180 lb subject. RESULTS: The modified Cooper-Harper Scale assesses desired task performance described as performance in a reduced gravity environment as compared to a 1G environment. Modified Cooper-Harper ratings of . 3 indicate no improvements are needed, ratings of 4-6 indicate improvements are desirable, and ratings . 7 indicate improvements are mandatory. DISCUSSION: Differences were noted in suited CH results based on environment at the same CG and suit pressure. Additionally, results suggest that CG location affects unsuited human performance. Subjects preferred locations near their natural CG over those that are high, aft, or a combination of high and aft. Further testing and analyses are planned to compare these unsuited results to suited performance.

Gernhardt, M.L.↗
NASA NTRS2012

885-nm Pumped Ceramic Nd:YAG Master Oscillator Power Amplifier Laser System

The performance of a traditional diode pumped solid-state laser that is typically pumped with 808-nm laser diode array (LDA) and crystalline Nd:YAG was improved by using 885-nm LDAs and ceramic Nd:YAG. The advantage is lower quantum defect, which will improve the thermal loading on laser gain medium, resulting in a higher-performance laser. The use of ceramic Nd:YAG allows a higher Nd dopant level that will make up the lower absorption at the 885-nm wavelength on Nd:YAG. When compared to traditional 808-nm pump, 885-nm diodes will have 30% less thermal load (or wasted heat) and will thus see a similar percentage improvement in the overall laser efficiency. In order to provide a more efficient laser system for future flight missions that require the use of low-repetition- rate ( 1% Nd. To make certain that the absorption at 885 nm is on the same par as the 808-nm diode, the Nd:YAG material needs to be doped with higher concentration of Nd. Ceramic Nd:YAG is the only material that can be tailored to specific needs.

Yu, Anthony↗
NASA NTRS2011

Calibrated Noise Measurements with Induced Receiver Gain Fluctuations

The lack of well-developed techniques for modeling changing statistical moments in our observations has stymied the application of stochastic process theory in science and engineering. These limitations were encountered when modeling the performance of radiometer calibration architectures and algorithms in the presence of non stationary receiver fluctuations. Analyses of measured signals have traditionally been limited to a single measurement series. Whereas in a radiometer that samples a set of noise references, the data collection can be treated as an ensemble set of measurements of the receiver state. Noise Assisted Data Analysis is a growing field of study with significant potential for aiding the understanding and modeling of non stationary processes. Typically, NADA entails adding noise to a signal to produce an ensemble set on which statistical analysis is performed. Alternatively as in radiometric measurements, mixing a signal with calibrated noise provides, through the calibration process, the means to detect deviations from the stationary assumption and thereby a measurement tool to characterize the signal's non stationary properties. Data sets comprised of calibrated noise measurements have been limited to those collected with naturally occurring fluctuations in the radiometer receiver. To examine the application of NADA using calibrated noise, a Receiver Gain Modulation Circuit (RGMC) was designed and built to modulate the gain of a radiometer receiver using an external signal. In 2010, an RGMC was installed and operated at the National Institute of Standards and Techniques (NIST) using their Noise Figure Radiometer (NFRad) and national standard noise references. The data collected is the first known set of calibrated noise measurements from a receiver with an externally modulated gain. As an initial step, sinusoidal and step-function signals were used to modulate the receiver gain, to evaluate the circuit characteristics and to study the performance of a variety of calibration algorithms. The receiver noise temperature and time-bandwidth product of the NFRad are calculated from the data. Statistical analysis using temporal-dependent calibration algorithms reveals that the natural occurring fluctuations in the receiver are stationary over long intervals (100s of seconds); however the receiver exhibits local non stationarity over the interval over which one set of reference measurements are collected. A variety of calibration algorithms have been applied to the data to assess algorithms' performance with the gain fluctuation signals. This presentation will describe the RGMC, experiment design and a comparative analysis of calibration algorithms.

Racette, Paul↗
NASA NTRS1992

A study of control approaches for large-angle beam slewing with an adaptive truss

This paper presents an analytical study of large-angle beam slewing with a double-octahedral adaptive truss and documents the performance of different control laws for simultaneous vibration control and beam slewing. A general nonlinear model of an adaptive truss and flexible beam is derived which includes a degree-of-freedom previously considered negligible for a double-octahedral adaptive truss actuated at its mid-plane. Linear and nonlinear, gain-scheduled, control laws are developed and applied to the nonlinear model for various large-angle slewing maneuvers. The nonlinear, gain-scheduled, control law is found to perform better than the linear control laws.

Warrington, Thomas J.↗
NASA NTRS1992

Mapping of sea bottom topography

Under suitable conditions the bottom topography of shallow seas is visible in remote sensing radar imagery. Two experiments were performed to establish which remote sensing technique or combination yields optimal imaging of bottom topography and which hydro-meteorological conditions are favorable. A further goal is to gain experience with these techniques. Two experiments were performed over an area in the North Sea near the measuring platform Meetpost Noordwijk (MPN). The bottom topography in the test area is dominated by sand waves. The crests of the sand waves are perpendicular to the coast line and the dominating (tidal-)current direction. A 4x4 sq km wide section of the test area was studied in more detail. The first experiment was undertaken on 16 Aug. 1989. During the experiment the following remote sensing instruments were used: Landsat-Thematic Mapper, and NASA/JPL Airborne Imaging Radar (AIR). The hydro-meteorological conditions; current, wind, wave, and air and water temperature were monitored by MPN, a ship of Rijkswaterstaat (the OCTANS), and a pitch-and-roll WAVEC-buoy. The second experiment took place on 12 July 1992. During this experiment data were collected with the NASA/JPL polarimetric synthetic aperture radar (SAR), and a five-band helicopter-borne scatterometer. Again the hydro-meteorological conditions were monitored at MPN and the OCTANS. Furthermore, interferometric radar data were collected.

Calkoen, C. J.↗
NASA NTRS1996

Performance Improvement Through Indexing of Turbine Airfoils: Numerical Simulation - Part 2

An experimental/analytical study has been conducted to determine the performance improvements achievable by circumferentially indexing succeeding rows of turbine stator airfoils. A series of tests was conducted to experimentally investigate stator wake clocking effects on the performance of the space shuttle main engine (SSME) alternate turbopump development (ATD) fuel turbine test article (TTA). The results from this study indicate that significant increases in stage efficiency can be attained through application of this airfoil clocking concept. Details of the experiment and its results are documented in part 1 of this paper. In order to gain insight into the mechanisms of the performance improvement, extensive computational fluid dynamics (CFD) simulations were executed. The subject of the present paper is the initial results from the CFD investigation of the configurations and conditions detailed in part 1 of the paper. To characterize the aerodynamic environments in the experimental test series, two-dimensional (2D), time accurate, multistage, viscous analyses were performed at the TTA midspan. Computational analyses for five different circumferential positions of the first stage stator have been completed. Details of the computational procedure and the results are presented. The analytical results verify the experimentally demonstrated performance improvement and are compared with data whenever possible. Predictions of time-averaged turbine efficiencies as well as gas conditions throughout the flow field are presented. An initial understanding of the turbine performance improvement mechanism based on the results from this investigation is described.

Griffin, Lisa W.↗
NASA NTRS2000

X-33 Ascent Flight Controller Design by Trajectory Linearization: A Singular Perturbational Approach

The flight control of X-33 poses a challenge to conventional gain-scheduled flight controllers due to its large attitude maneuvers from liftoff to orbit and reentry. In addition, a wide range of uncertainties in vehicle handling qualities and disturbances must be accommodated by the attitude control system. Nonlinear tracking and decoupling control by trajectory linearization can be viewed as the ideal gain-scheduling controller designed at every point on the flight trajectory. Therefore it provides robust stability and performance at all stages of flight without interpolation of controller gains and eliminates costly controller redesigns due to minor airframe alteration or mission reconfiguration. In this paper, a prototype trajectory linearization design for an X-33 ascent flight controller is presented along with 3-DOF and 6-DOF simulation results. It is noted that the 6-DOF results were obtained from the 3-DOF design with only a few hours of tuning, which demonstrates the inherent robustness of the design technique. It is this "plug-and-play" feature that is much needed by NASA for the development, test and routine operations of the RLV'S. Plans for further research are also presented, and refined 6-DOF simulation results will be presented in the final version of the paper.

Zhu, J. Jim↗
NASA NTRS1999

X-33 Ascent Flight Controller Design by Trajectory Linearization: A Singular Perturbational Approach

The flight control of X-33 poses a challenge to conventional gain-scheduled flight controllers due to its large attitude maneuvers from liftoff to orbit and reentry. In addition, a wide range of uncertainties in vehicle handling qualities and disturbances must be accommodated by the attitude control system. Nonlinear tracking and decoupling control by trajectory linearization can be viewed as the ideal gain-scheduling controller designed at every point on the flight trajectory. Therefore it provides robust stability and performance at all stages of flight without interpolation of controller gains, and eliminates costly controller redesigns due to minor airframe alteration or mission reconfiguration. A prototype trajectory linearization design for X-33 ascent flight controller was designed and tested with 3-DOF and 6-DOF simulations during the 10 weeks SFFP. It is noted that the 6-DOF results were obtained from the 3-DOF design with only a few hours of tuning, which demonstrates the inherent robustness of the design technique. It is this "plug-and-play" feature that is much needed by NASA for the development, test and routine operations of the RLVs. Plans for further research are also presented.

Zhu, J. Jim↗
NASA NTRS1970

Ferrite attenuator modulation improves antenna performance

Ferrite attenuator inserted into appropriate waveguide reduces the gain of the antenna element which is causing interference. Modulating the ferrite attenuator to change the antenna gain at the receive frequency permits ground tracking until the antenna is no longer needed.

Hooks, J. C.↗
NASA NTRS2014

Preparation and Integration of ALHAT Precision Landing Technology for Morpheus Flight Testing

The Autonomous precision Landing and Hazard Avoidance Technology (ALHAT) project has developed a suite of prototype sensors for enabling autonomous and safe precision land- ing of robotic or crewed vehicles on solid solar bodies under varying terrain lighting condi- tions. The sensors include a Lidar-based Hazard Detection System (HDS), a multipurpose Navigation Doppler Lidar (NDL), and a long-range Laser Altimeter (LAlt). Preparation for terrestrial ight testing of ALHAT onboard the Morpheus free- ying, rocket-propelled ight test vehicle has been in progress since 2012, with ight tests over a lunar-like ter- rain eld occurring in Spring 2014. Signi cant work e orts within both the ALHAT and Morpheus projects has been required in the preparation of the sensors, vehicle, and test facilities for interfacing, integrating and verifying overall system performance to ensure readiness for ight testing. The ALHAT sensors have undergone numerous stand-alone sensor tests, simulations, and calibrations, along with integrated-system tests in special- ized gantries, trucks, helicopters and xed-wing aircraft. A lunar-like terrain environment was constructed for ALHAT system testing during Morpheus ights, and vibration and thermal testing of the ALHAT sensors was performed based on Morpheus ights prior to ALHAT integration. High- delity simulations were implemented to gain insight into integrated ALHAT sensors and Morpheus GN&C system performance, and command and telemetry interfacing and functional testing was conducted once the ALHAT sensors and electronics were integrated onto Morpheus. This paper captures some of the details and lessons learned in the planning, preparation and integration of the individual ALHAT sen- sors, the vehicle, and the test environment that led up to the joint ight tests.

Carson, John M., III↗
NASA NTRS2005

Putting EVM to the Test

IN MANY INSTANCES THERE IS NO FOREWARNING; SCHEDULES slip, costs soar, and the project manager is faced with the near impossible task of explaining why each impact occurred. With contractors performing the majority of the work, the management job can become even more obscure. The simple lack of proximity to the contractor can limit effective communication. Add to that a mixture of cultural differences and a desire for the contractor to portray the most optimistic view of their performance, and you create an even more difficult task for the project manager. This was the scenario when the Habitat Holding Rack (HHR) manager at Marshall Space Flight Center (MSFC), Stacy Counts, was introduced to the overall concept of Earned Value Management (EVM). Faced with increased costs (which eventually resulted in decreased scope of the project), continued schedule slides, and several technical anomalies, she was looking for a way to gain a better handle on the project performance. As a component of the Space Station Biological Research Program (SSBRP), the HHR project is an integral piece of the Program content. The HHR is the first rack hardware to be delivered for the Program and has therefore been the first rack to move through the trials of test and verification-documenting anomalies and technical difficulties that will benefit the other SSBRP rack projects. For these reasons, the HHR maintained high visibility throughout the manufacturing and assembly process, continuing through test and verification activities. Needless to say, the higher visibility emphasized the need for improved performance on this project. And to improve project performance, Stacy first had to figure out how to measure the cost, schedule and technical objectives effectively.

Kerby, Jerald↗
NASA NTRS2016

Organizational Risk and Opportunity Management: Concepts and Processes for NASA's Consideration

The focus of this report is on the development of a framework and overall approach that serves the interests of nonprofit and Government organizations like NASA that focus on developing and/or applying new technology (henceforth referred to as organizations like NASA). These interests tend to place emphasis on performing services and achieving scientific and technical gains more than on achieving financial investment goals, which is the province of commercial enterprises. In addition, the objectives of organizations like NASA extend to institutional development and maintenance, financial health, legal and reputational protection, education and partnerships, and mandated milestone achievements. This report discusses the philosophical underpinnings of OROM for organizations like NASA, the integration of OROM with existing management processes, and the nature of the activities that are performed to implement OROM within this context. The proposed framework includes a set of core principles that would be essential to any successful OROM approach, along with some features that are currently under development and are continuing to evolve. The report is intended to foster discussion of OROM at NASA in order to reach a consensus on the optimum approach for the agency.

Risk↗