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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 253 records · Page 14
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

Investigation of the turbulent wind field below 500 feet altitude at the Eastern Test Range, Florida

A detailed analysis of wind profiles and turbulence at the 150 m Cape Kennedy Meteorological Tower is presented. Various methods are explored for the estimation of wind profiles, wind variances, high-frequency spectra, and coherences between various levels, given roughness length and either low-level wind and temperature data, or geostrophic wind and insolation. The relationship between planetary Richardson number, insolation, and geostrophic wind is explored empirically. Techniques were devised which resulted in surface stresses reasonably well correlated with the surface stresses obtained from low-level data. Finally, practical methods are suggested for the estimation of wind profiles and wind statistics.

Blackadar, A. K.↗
NASA NTRS1996

Testing of hypotheses about altitude decompression sickness by statistical analyses

This communication extends a statistical analysis of forced-descent decompression sickness at altitude in exercising subjects (J Appl Physiol 1994; 76:2726-2734) with a data subset having an additional explanatory variable, rate of ascent. The original explanatory variables for risk-function analysis were environmental pressure of the altitude, duration of exposure, and duration of pure-O2 breathing before exposure; the best fit was consistent with the idea that instantaneous risk increases linearly as altitude exposure continues. Use of the new explanatory variable improved the fit of the smaller data subset, as indicated by log likelihood. Also, with ascent rate accounted for, replacement of the term for linear accrual of instantaneous risk by a term for rise and then decay made a highly significant improvement upon the original model (log likelihood increased by 37 log units). The authors conclude that a more representative data set and removal of the variability attributable to ascent rate allowed the rise-and-decay mechanism, which is expected from theory and observations, to become manifest.

NASA Center JSC↗
NASA NTRS2007

The Ares I-1 Flight Test--Paving the Road for the Ares I Crew Launch Vehicle

In accordance with the U.S. Vision for Space Exploration and the nation's desire to again send humans to explore beyond Earth orbit, NASA has been tasked to send human beings to the moon, Mars, and beyond. It has been 30 years since the United States last designed and built a human-rated launch vehicle. NASA is now building the Ares I crew launch vehicle, which will loft the Orion crew exploration vehicle into orbit, and the Ares V cargo launch vehicle, which will launch the Lunar Surface Access Module and Earth departure stage to rendezvous Orion for missions to the moon. NASA has marshaled unique resources from the government and private sectors to perform the technically and programmatically complex work of delivering astronauts to orbit early next decade, followed by heavy cargo late next decade. Our experiences with Saturn and the Shuttle have taught us the value of adhering to sound systems engineering, such as the "test as you fly" principle, while applying aerospace best practices and lessons learned. If we are to fly humans safely aboard a launch vehicle, we must employ a variety of methodologies to reduce the technical, schedule, and cost risks inherent in the complex business of space transportation. During the Saturn development effort, NASA conducted multiple demonstration and verification flight tests to prove technology in its operating environment before relying upon it for human spaceflight. Less testing on the integrated Shuttle system did not reduce cost or schedule. NASA plans a progressive series of demonstration (ascent), verification (orbital), and mission flight tests to supplement ground research and high-altitude subsystem testing with real-world data, factoring the results of each test into the next one. In this way, sophisticated analytical models and tools, many of which were not available during Saturn and Shuttle, will be calibrated and we will gain confidence in their predictions, as we gain hands-on experience in operating the first of two new launch vehicle systems. The Ares I-1 flight test vehicle (FTV) will incorporate a mix of flight and mockup hardware, reflecting a configuration similar in mass, weight, and shape (outer mold line or OML) to the operational vehicle. It will be powered by a four-segment reusable solid rocket booster (RSRB), which is currently in Shuttle inventory, and will be modified to include a fifth, inert segment that makes it approximately the same size and weight as the five segment RSRB, which will be available for the second flight test in 2012. The Ares I-1 vehicle configuration is shown. Each test flight has specific objectives appropriate to the design analysis cycle in progress. The Ares I-1 demonstration test, slated for April 2009, gives NASA its first opportunity to gather critical data about the flight dynamics of the integrated launch vehicle stack, understand how to control its roll during flight, and other characterize the severe stage separation environment that the upper stage will experience during future operational flights. NASA also will begin the process of modifying the launch infrastructure and fine-tuning ground and mission operational scenarios, as NASA transitions from the Shuttle to the Ares/Orion system.

Davis, Stephan R.↗
NASA NTRS2003

The X-38 Spacecraft Fault-Tolerant Avionics System

In 1995 NASA began an experimental program to develop a reusable crew return vehicle (CRV) for the International Space Station. The purpose of the CRV was threefold: (i) to bring home an injured or ill crewmember; (ii) to bring home the entire crew if the Shuttle fleet was grounded; and (iii) to evacuate the crew in the case of an imminent Station threat (i.e., fire, decompression, etc). Built at the Johnson Space Center, were two approach and landing prototypes and one spacecraft demonstrator (called V201). A series of increasingly complex ground subsystem tests were completed, and eight successful high-altitude drop tests were achieved to prove the design concept. In this program, an unprecedented amount of commercial-off-the-shelf technology was utilized in this first crewed spacecraft NASA has built since the Shuttle program. Unfortunately, in 2002 the program was canceled due to changing Agency priorities. The vehicle was 80% complete and the program was shut down in such a manner as to preserve design, development, test and engineering data. This paper describes the X-38 V201 fault-tolerant avionics system. Based on Draper Laboratory's Byzantine-resilient fault-tolerant parallel processing system and their "network element" hardware, each flight computer exchanges information on a strict timescale to process input data, compare results, and issue voted vehicle output commands. Major accomplishments achieved in this development include: (i) a space qualified two-fault tolerant design using mostly COTS (hardware and operating system); (ii) a single event upset tolerant network element board, (iii) on-the-fly recovery of a failed processor; (iv) use of synched cache; (v) realignment of memory to bring back a failed channel; (vi) flight code automatically generated from the master measurement list; and (vii) built in-house by a team of civil servants and support contractors. This paper will present an overview of the avionics system and the hardware implementation, as well as the system software and vehicle command & telemetry functions. Potential improvements and lessons learned on this program are also discussed.

Kouba,Coy↗
NASA NTRS1984

In-flight thrust determination on a real-time basis

A real time computer program was implemented on a F-15 jet fighter to monitor in-flight engine performance of a Digital Electronic Engine Controlled (DEES) F-100 engine. The application of two gas generator methods to calculate in-flight thrust real time is described. A comparison was made between the actual results and those predicted by an engine model simulation. The percent difference between the two methods was compared to the predicted uncertainty based on instrumentation and model uncertainty and agreed closely with the results found during altitude facility testing. Data was obtained from acceleration runs of various altitudes at maximum power settings with and without afterburner. Real time in-flight thrust measurement was a major advancement to flight test productivity and was accomplished with no loss in accuracy over previous post flight methods.

Ray, R. J.↗
NASA NTRS2013

Modeling Commercial Turbofan Engine Icing Risk With Ice Crystal Ingestion

The occurrence of ice accretion within commercial high bypass aircraft turbine engines has been reported under certain atmospheric conditions. Engine anomalies have taken place at high altitudes that have been attributed to ice crystal ingestion, partially melting, and ice accretion on the compression system components. The result was degraded engine performance, and one or more of the following: loss of thrust control (roll back), compressor surge or stall, and flameout of the combustor. As ice crystals are ingested into the fan and low pressure compression system, the increase in air temperature causes a portion of the ice crystals to melt. It is hypothesized that this allows the ice-water mixture to cover the metal surfaces of the compressor stationary components which leads to ice accretion through evaporative cooling. Ice accretion causes a blockage which subsequently results in the deterioration in performance of the compressor and engine. The focus of this research is to apply an engine icing computational tool to simulate the flow through a turbofan engine and assess the risk of ice accretion. The tool is comprised of an engine system thermodynamic cycle code, a compressor flow analysis code, and an ice particle melt code that has the capability of determining the rate of sublimation, melting, and evaporation through the compressor flow path, without modeling the actual ice accretion. A commercial turbofan engine which has previously experienced icing events during operation in a high altitude ice crystal environment has been tested in the Propulsion Systems Laboratory (PSL) altitude test facility at NASA Glenn Research Center. The PSL has the capability to produce a continuous ice cloud which are ingested by the engine during operation over a range of altitude conditions. The PSL test results confirmed that there was ice accretion in the engine due to ice crystal ingestion, at the same simulated altitude operating conditions as experienced previously in flight. The computational tool was utilized to help guide a portion of the PSL testing, and was used to predict ice accretion could also occur at significantly lower altitudes. The predictions were qualitatively verified by subsequent testing of the engine in the PSL. The PSL test has helped to calibrate the engine icing computational tool to assess the risk of ice accretion. The results from the computer simulation identified prevalent trends in wet bulb temperature, ice particle melt ratio, and engine inlet temperature as a function of altitude for predicting engine icing risk due to ice crystal ingestion.

Jorgenson, Philip C. E.↗
NASA NTRS2014

Modeling of Commercial Turbofan Engine With Ice Crystal Ingestion: Follow-On

The occurrence of ice accretion within commercial high bypass aircraft turbine engines has been reported under certain atmospheric conditions. Engine anomalies have taken place at high altitudes that have been attributed to ice crystal ingestion, partially melting, and ice accretion on the compression system components. The result was degraded engine performance, and one or more of the following: loss of thrust control (roll back), compressor surge or stall, and flameout of the combustor. As ice crystals are ingested into the fan and low pressure compression system, the increase in air temperature causes a portion of the ice crystals to melt. It is hypothesized that this allows the ice-water mixture to cover the metal surfaces of the compressor stationary components which leads to ice accretion through evaporative cooling. Ice accretion causes a blockage which subsequently results in the deterioration in performance of the compressor and engine. The focus of this research is to apply an engine icing computational tool to simulate the flow through a turbofan engine and assess the risk of ice accretion. The tool is comprised of an engine system thermodynamic cycle code, a compressor flow analysis code, and an ice particle melt code that has the capability of determining the rate of sublimation, melting, and evaporation through the compressor flow path, without modeling the actual ice accretion. A commercial turbofan engine which has previously experienced icing events during operation in a high altitude ice crystal environment has been tested in the Propulsion Systems Laboratory (PSL) altitude test facility at NASA Glenn Research Center. The PSL has the capability to produce a continuous ice cloud which is ingested by the engine during operation over a range of altitude conditions. The PSL test results confirmed that there was ice accretion in the engine due to ice crystal ingestion, at the same simulated altitude operating conditions as experienced previously in flight. The computational tool was utilized to help guide a portion of the PSL testing, and was used to predict ice accretion could also occur at significantly lower altitudes. The predictions were qualitatively verified by subsequent testing of the engine in the PSL. In a previous study, analysis of select PSL test data points helped to calibrate the engine icing computational tool to assess the risk of ice accretion. This current study is a continuation of that data analysis effort. The study focused on tracking the variations in wet bulb temperature and ice particle melt ratio through the engine core flow path. The results from this study have identified trends, while also identifying gaps in understanding as to how the local wet bulb temperature and melt ratio affects the risk of ice accretion and subsequent engine behavior.

Jorgenson, Philip C. E.↗
NASA NTRS2014

Modeling of Commercial Turbofan Engine with Ice Crystal Ingestion; Follow-On

The occurrence of ice accretion within commercial high bypass aircraft turbine engines has been reported under certain atmospheric conditions. Engine anomalies have taken place at high altitudes that have been attributed to ice crystal ingestion, partially melting, and ice accretion on the compression system components. The result was degraded engine performance, and one or more of the following: loss of thrust control (roll back), compressor surge or stall, and flameout of the combustor. As ice crystals are ingested into the fan and low pressure compression system, the increase in air temperature causes a portion of the ice crystals to melt. It is hypothesized that this allows the ice-water mixture to cover the metal surfaces of the compressor stationary components which leads to ice accretion through evaporative cooling. Ice accretion causes a blockage which subsequently results in the deterioration in performance of the compressor and engine. The focus of this research is to apply an engine icing computational tool to simulate the flow through a turbofan engine and assess the risk of ice accretion. The tool is comprised of an engine system thermodynamic cycle code, a compressor flow analysis code, and an ice particle melt code that has the capability of determining the rate of sublimation, melting, and evaporation through the compressor flow path, without modeling the actual ice accretion. A commercial turbofan engine which has previously experienced icing events during operation in a high altitude ice crystal environment has been tested in the Propulsion Systems Laboratory (PSL) altitude test facility at NASA Glenn Research Center. The PSL has the capability to produce a continuous ice cloud which is ingested by the engine during operation over a range of altitude conditions. The PSL test results confirmed that there was ice accretion in the engine due to ice crystal ingestion, at the same simulated altitude operating conditions as experienced previously in flight. The computational tool was utilized to help guide a portion of the PSL testing, and was used to predict ice accretion could also occur at significantly lower altitudes. The predictions were qualitatively verified by subsequent testing of the engine in the PSL. In a previous study, analysis of select PSL test data points helped to calibrate the engine icing computational tool to assess the risk of ice accretion. This current study is a continuation of that data analysis effort. The study focused on tracking the variations in wet bulb temperature and ice particle melt ratio through the engine core flow path. The results from this study have identified trends, while also identifying gaps in understanding as to how the local wet bulb temperature and melt ratio affects the risk of ice accretion and subsequent engine behavior.

Jorgenson, Philip C. E.↗
NASA NTRS1995

Flight test of a low-altitude helicopter guidance system with obstacle avoidance capability

Military aircraft regularly conduct missions that include low-atltitude, near-terrain flight in order to increase covertness and payload effectiveness. Civilian applications include airborne fire fighting, police surveillance, search and rescue, and helicopter emergency medical service. Several fixed-wing aircraft now employ terrain elevation maps and forward-pointed radars to achieve automated terrain following or terrain avoidance flight. Similar systems specialized to helicopters and their flight regime have not received as much attention. A helicopter guidance system relying on digitized terrain elevation maps has been developed that employs airborne navigation, mission requirements, aircraft performance limits, and radar altimeter returns to generate a valley-seeking, low-altitude trajectory between waypoints. The guidance trajectory is symbolically presented to the pilot on a helmet mounted display. This system has been flight tested to 150 ft (45.7 m) above ground level altitude at 80 kts, and is primarily limited by the ability of the pilot to perform manual detection and avoidance of unmapped hazards. In this study, a wide field of view laser radar sensor has been incorporated into this guidance system to assist the pilot in obstacle detection and avoidance, while expanding the system's operational flight envelope. The results from early flight tests of this system are presented. Low-altitude missions to 100 ft (30.5 m) altitude at 80n kts in the presence of unmapped natural and man-made obstacles were demonstrated while the pilot maintained situational awareness and tracking of the guidance trajectory. Further reductions in altitude are expected with continued flight testing.

Zelenka, Richard E.↗
NASA NTRS1997

Rocketdyne RBCC Concept Development

Rocketdyne is pursuing the conceptual design and development of a Rocket Based Combined Cycle (BBCC) engine for booster and SSTO, advanced reusable space transportation systems under the Advanced Reusable Transportation Technologies contract with NASA Marshall Space Flight Center. The Rocketdyne concept is a fixed geometry integrated rocket, ramjet, scramjet which is hydrogen fueled and uses hydrogen regenerative cooling. Vision vehicle integration studies have determined that scramjet operation to the range of Mach 10 to 12 has high payoff for low cost reusable space transportation. Rocketdyne is internally developing versions of the concept for other applications in high speed aircraft and missiles with hydrocarbon fuel systems. A subscale engine ground test program is underway for all modes of operation from takeoff to Mach 8. High altitude rocket tests will only be completed as part of the ground test program to validate high expansion ratio performance. A unique feature of the ground test series is the inclusion of dynamic trajectory simulation with real time Mach number, altitude, engine throttling, and RBCC mode changes in a specially modified freejet test facility at GASL. Preliminary cold flow air augmented rocket and all rocket test results have met program goals and have been used to integrate all modes of operation in a single combustor design with a fixed geometry inlet for design confirmation tests. A water cooled subscale engine is currently being fabricated for test during the early part of 1998.

Ortwerth, P.↗
NASA NTRS1973

The Viking parachute qualification test technique.

The parachute system for NASA's Viking '75 Mars lander was flight qualified in four high-altitude flight tests at the White Sands Missile range (WSMR). A balloon system lifted a full-scale simulated Viking spacecraft to an altitude where a varying number of rocket motors were used to propel the high drag, lifting test vehicle to test conditions which would simulate the range of entry conditions expected at Mars. A ground-commanded cold gas pointing system located on the balloon system provided powered vehicle azimuth control to insure that the flight trajectory remained within the WSMR boundaries. A unique ground-based computer-radar system was employed to monitor inflight performance of the powered vehicle and insure that command ignition of the parachute mortar occurred at the required test conditions of Mach number and dynamic pressure. Performance data were obtained from cameras, telemetry, and radar.

Raper, J. L.↗
NASA NTRSDate not supplied

Artemis Innovative Assembly and Integration Operations of the Launch Abort Systemat KSC

This paper describes the Artemis program assembly and integration approach that enables affordable and low risk processing operations for the Launch Abort System at KSC. NASA is currently developing the Artemis 1 spacecraft to meet the test objectives of an uncrewed orbital mission to the moon and return to earth in 2021. The Artemis Orion spacecraft consists of a Crew Module (CM), a Service Module (SM), and a Launch Abort System (LAS) to safely transport a crew of 4 to the moon and return to earth. The LAS enables the CM to have an abort capability for the crew during the launch phase of the mission from the launch pad throughout the ascent phase. The LAS includes motor elements for abort, attitude control, and stage separation is assembled at the Launch Abort System Facility (LASF) adjacent to the CM/SM (CSM) assembly operations in the Neil Armstrong Operations and Checkout Building (O&C) at KSC. The LAS integration to the CSM is completed in the LASF and the completed Artemis spacecraft is integrated to the Space Launch System (SLS) in the Vehicle Assembly Building (VAB) at KSC. A significant LAS development flight test milestone was recently completed in 2019 for the Ascent Abort (AA-2) flight test at Cape Canaveral Air Force Station where a high-altitude abort test was successfully achieved using a Peacekeeper booster stage exercising all of the LAS systems including propulsion, avionics, and pyrotechnics demonstrating he LAS readiness for crewed flight. The first operational flight of the LAS will be for the Artemis 2 mission which is the first crewed mission for the Orion program planned in 2023.

William J Koenig↗
NASA NTRSDate not supplied

High-Altitude ADS-B/GPS LPV Flight Tests on a NASA ER-2 Research Airplane

The research presented in this paper describes the conceptual design of a system architecture that integrates Automatic Dependent Surveillance-Broadcast (ADS-B) and Global Positioning System (GPS) Localizer Performance Vertical (LPV) guidance technology onto a unique high-altitude research airplane: a United States Air Force (USAF) / Lockheed Martin (Bethesda, Maryland) Aeronautics U-2S airplane. The design features modern display capabilities to provide air-to-air surveillance and precision navigation, to adhere to Federal Aviation Administration (FAA) certification standards for operations in upper Class E airspace. The National Aeronautics and Space Administration (NASA) variant of the U-2S, now called the Earth Resources (ER-2) airplane, remains unrivaled in the art of sustained high-altitude flight for scientific expeditions. Capable of routinely cruising above flight level (FL) 650 that had been considered, at inception, the domain of only the most elite experimental research aircraft types. Nicknamed the Dragon Lady, this U-2S research testbed is still one of the most advanced aircraft in the world. The exceptional military design of the vehicle, security guidelines, and the performance envelope of the ER-2 posed unique challenges to the integration of modern civilian avionics. ADS-B epitomizes the next generation of surveillance technology, incorporating both air and ground aspects. ADS-B provides air traffic control (ATC) with a more accurate picture of the three-dimensional positioning of aircraft in various phases of flight, including en route, terminal, approach, and ground operations. The airborne surveillance system broadcasts its identification, position, altitude, velocity, and other information. GPS LPV represents a significant advancement in aviation technology, emphasizing the pivotal role that GPS and Performance-Based Navigation concepts will play in the foreseeable future. This technology represents a shift from sensor-based navigation to performance-based navigation, allowing for more flexible and efficient use of airspace. This research described herein is structured as follows: Section II, “Systems Background,” provides a systems background and description of an ADS-B and GPS LPV system equipped on the high-altitude ER-2 research airplane to satisfy the FAA airworthiness requirements for high-altitude flight operations. Section III, “Flight Test System,” describes the flight-test airplane systems. Section IV, “Analysis of GPS SBAS, Safety, and Ground Tests,” provides an overview of the GPS Satellite-Based Augmentation System (SBAS) and an analysis of the GPS LPV metrics, safety, and ground tests. Section V, “High-Altitude Flight Tests,” describes the high-altitude flight tests, including 3 flight-test results, analysis, human factors, and lessons learned. Section VI, the conclusion, draws insights from the lessons learned, discusses the design challenges associated with ADS-B and GPS LPV, and showcases the paramount significance of these pivotal technologies in aircraft surveillance and navigation.

Ricardo A. Arteaga↗
NASA NTRS2016

Update on the NASA Glenn Propulsion Systems Lab Ice Crystal Cloud Characterization (2015)

NASA Glenn's Propulsion Systems Lab (PSL), an altitude engine test facility, was outfitted with a spray system to generate ice crystals. The first ice crystal characterization test occurred in 2012. At PSL, turbine engines and driven rigs can experience ice crystal icing at flight altitudes, temperatures and Mach numbers. To support these tests, four ice crystal characterizations have been conducted in two different facility configurations. In addition, super-cooled liquid and mixed phase clouds have also been generated. This paper will discuss the recent learning from the previous two calibrations. It will describe some of the 12-parameter calibration space, and how those parameters interact with each other, the instrumentation used to characterize the cloud and present a sample of the cloud characterization results.

Ice Clouds↗
NASA NTRS2009

Defining Nitrogen Kinetics for Air Break in Prebreathe

Actual tissue nitrogen (N2) kinetics are complex; the uptake and elimination is often approximated with a single half-time compartment in statistical descriptions of denitrogenation [prebreathe (PB)] protocols. Air breaks during PB complicate N2 kinetics. A comparison of symmetrical versus asymmetrical N2 kinetics was performed using the time to onset of hypobaric decompression sickness (DCS) as a surrogate for actual venous N2 tension. Published results of 12 tests involving 179 hypobaric exposures in altitude chambers after PB, with and without air breaks, provide the complex protocols from which to model N2 kinetics. DCS survival time for combined control and air breaks were described with an accelerated log logistic model where N2 uptake and elimination before, during, and after the air break was computed with a simple exponential function or a function that changed half-time depending on ambient N2 partial pressure. P1N2-P2 = delta P defined DCS dose for each altitude exposure, where P2 was the test altitude and P1N2 was computed N2 pressure at the beginning of the altitude exposure. The log likelihood (LL) without DCS dose (null model) was -155.6, and improved (best-fit) to -97.2 when dose was defined with a 240 min half-time for both N2 elimination and uptake during the PB. The description of DCS survival time was less precise with asymmetrical N2 kinetics, for example, LL was -98.9 with 240 min half-time elimination and 120 min half-time uptake. The statistical regression described survival time mechanistically linked to symmetrical N2 kinetics during PBs that also included air breaks. The results are data-specific, and additional data may change the conclusion. The regression is useful to compute additional PB time to compensate for an air break in PB within the narrow range of tested conditions.

Conkin, Johnny↗