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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 1,063 records · Page 59
All sourcesNASA NTRSDOE OSTI
NASA NTRS1998

Development and Testing of a High Stability Engine Control (HISTEC) System

Flight tests were recently completed to demonstrate an inlet-distortion-tolerant engine control system. These flight tests were part of NASA's High Stability Engine Control (HISTEC) program. The objective of the HISTEC program was to design, develop, and flight demonstrate an advanced integrated engine control system that uses measurement-based, real-time estimates of inlet airflow distortion to enhance engine stability. With improved stability and tolerance of inlet airflow distortion, future engine designs may benefit from a reduction in design stall-margin requirements and enhanced reliability, with a corresponding increase in performance and decrease in fuel consumption. This paper describes the HISTEC methodology, presents an aircraft test bed description (including HISTEC-specific modifications) and verification and validation ground tests. Additionally, flight test safety considerations, test plan and technique design and approach, and flight operations are addressed. Some illustrative results are presented to demonstrate the type of analysis and results produced from the flight test program.

Orme, John S.↗
NASA NTRS1999

Flight Test Results for the NICMOS Cryocooler

In October 1998 a mechanical cryocooler and cryogenic circulator loop were flown on NASA's STS-95 as part of the Hubble Orbital System Test (HOST). The system will be installed on the Hubble Space Telescope (HST) during Service Mission #3 in 2000 and will provide cooling to the Near Infrared Camera and Multi-Object Spectrometer (NICMOS). It will extend the useful life of that instrument by 5 to 10 years. This was the first successful space demonstration of a turbobrayton cryocooler. The cooler is a single stage reverse Brayton type, using low-vibration high-speed miniature turbomachines for the compression and expansion functions. A miniature centrifugal cryogenic circulator is used to deliver refrigerated neon to the instrument. During the mission, the cooler operated without anomalies for approximately 185 hours over a range of conditions to verify its mechanical, thermodynamic and control functions. The cryocooler satisfied all mission objectives including maximum cooldown to near-design operating conditions, warm and cold starts and stops, operation at near-design temperatures, and demonstration of long-term temperature stability. This paper presents a description of the cooler and its operation during the HOST flight.

Dolan, F. X.↗
NASA NTRSDate not supplied

Integration of Automated Systems (IAS) Flight Test Overview

The Integration of Automated Systems (IAS) Project is conducting a series of 2023 flight tests supporting NASA's Advanced Air Mobility (AAM) and National Campaign efforts. These flights include crewed, test (i.e., ownship) and traffic (i.e., intruder) aircraft that will fly with unique technologies onboard. The presentation will include overviews of the Hazard Perception and Avoidance (HPA) and Flight Path Management (FPM) technical areas but will focus primarily on HPA. HPA will test the FAA's Airborne Collision Avoidance System X (ACAS X), a next-generation collision avoidance tool developed to support different aircraft types and operations. The rotorcraft variant, ACAS Xr, is designed to accommodate existing helicopter platforms and in-development, vertical takeoff and landing (VTOL) concepts, which are critical to the emerging AAM concept of operations. Two configurations of ACAS Xr will be examined: Collision Avoidance System (CAS, similar to the Traffic Collision Avoidance System [TCAS] II) and Detect and Avoid (DAA, previously developed to provide added situational awareness for uncrewed aircraft). Additionally, this system will be explored during cruise and low-speed flight as well as flights within en-route, structured (i.e., dense/urban), and terminal airspaces. Scripted flight conflicts will be conducted, and these conflicts will be mitigated through maneuvers that are manual (i.e., performed by the pilots) or automated (i.e., achieved by the cooperation of the program middleware and onboard ownship systems). Objective data will be collected involving system and pilot performance as well as pilot decisions; subjective data will include pilot opinions of ACAS Xr's alerting and guidance as well as the automated maneuvers.

detect and avoid↗
NASA NTRS2016

A Study of Flexible Composites for Expandable Space Structures

Payload volume for launch vehicles is a critical constraint that impacts spacecraft design. Deployment mechanisms, such as those used for solar arrays and antennas, are approaches that have successfully accommodated this constraint, however, providing pressurized volumes that can be packaged compactly at launch and expanded in space is still a challenge. One approach that has been under development for many years is to utilize softgoods - woven fabric for straps, cloth, and with appropriate coatings, bladders - to provide this expandable pressure vessel capability. The mechanics of woven structure is complicated by a response that is nonlinear and often nonrepeatable due to the discrete nature of the woven fiber architecture. This complexity reduces engineering confidence to reliably design and certify these structures, which increases costs due to increased requirements for system testing. The present study explores flexible composite materials systems as an alternative to the heritage softgoods approach. Materials were obtained from vendors who utilize flexible composites for non-aerospace products to determine some initial physical and mechanical properties of the materials. Uniaxial mechanical testing was performed to obtain the stress-strain response of the flexible composites and the failure behavior. A failure criterion was developed from the data, and a space habitat application was used to provide an estimate of the relative performance of flexible composites compared to the heritage softgoods approach. Initial results are promising with a 25% mass savings estimated for the flexible composite solution.

Scotti, Stephen J.↗
NASA NTRS1987

VLSI-Chip Tester

Compact test set integrated in computer-aided design system. Test set performs functional tests on very-large-scale integrated (VLSI) circuits. Makes tests from points within VLSI chip as well as at input and output pins. Used for quality control and design; in latter capacity, checks internal logic functions on chip and feed results directly to computer-aided design system for correction. Also simulates operation of chip design before chip is made. VLSI Tester contains three power supplies, control logic, and standard multibus circuit board in aluminum chassis. Chassis fits under platform of microprobe station. Multibus board links tester to interactive terminals and to host computer.

Deutsch, Leslie J.↗
NASA NTRS1973

Development testing of a shuttle urine collection system

Flight tests conducted in December 1973 demonstrated the ability of an unisexual urine collection subsystem to function in a zero-g environment. The urinal, which could be adjusted with three degrees of freedom, accommodated 16 female test subjects with a wide range of stature, as well as five male test subjects. The urinal was in intimate contact with the female and was contoured to form an effective air seal at the periphery. When positioned 2-4 inches forward, the urinal could be used for male collection and contact was not required.

Source record↗
NASA NTRS1984

Performance testing of the Galileo attitude control system

Performance testing plans, procedures, and initial results for the Galileo Attitude and Articulation Control Subsystem are described. The objectives of performance testing include test bed comparisons, examining the interactions between spacecraft dynamics and controllers, and verifying the ability to tune control algorithms in flight to meet specific performance requirements. Two primary test beds are described. One, the Integration Test Laboratory, drives actual flight hardware components and support equipment with a real time computer simulation of spacecraft dynamics. The other, the Functional Simulator, is a nonreal time computer simulation with high fidelity spacecraft dynamics, including flexible appendages, fuel slosh, and simulated hardware components. Initial Functional Simulator results are presented which illustrate spacecraft response to open loop spin-up and turn commands. A closed loop sun acquisition turn is also demonstrated. Future tests for verifying performance of attitude determination, spacecraft control, and scan platform pointing functions are outlined.

Bell, C. E.↗
NASA NTRS2008

Distributed Avionics and Software Verification for the Constellation Program

This viewgraph presentation reviews the planned verification of the avionics and software being developed for the Constellation program.The Constellation Distributed System Integration Laboratory (DSIL) will consist of multiple System Integration Labs (SILs), Simulators, Emulators, Testbeds, and Control Centers interacting with each other over a broadband network to provide virtual test systems for multiple test scenarios.

Hood, Laura E.↗
NASA NTRS1993

Mars Observer System Thermal Vacuum Test and Its Cost Saving Approach

The Mars Observer spacecraft underwent a successful system thermal vacuum (STV) test in March 1992, meeting all five primary objectives. This paper presents a description of the spacecraft and the test configuration, as well as a discussion of the test results and how the test objectives were successfully met. It then describes some of the cost-saving methods used in this test. These include the early commitment to restricting the total test time to 300 hours, the timely completion of test control documentation, use of IR heating instead of solar simulation, use of non-flight structural heaters, and the in-test modification of test phases to account for unexpected deviations from pre-test predictions.

Mars↗
NASA NTRS1974

A remotely augmented vehicle approach to flight testing RPV control systems

A remotely augmented vehicle concept for flight testing advanced control systems was developed as an outgrowth of a remotely piloted research vehicle (RPV) program in which control laws are implemented through telemetry uplink and downlink data channels using a general purpose ground based digital computer which provides the control law computations. Some advantages of this approach are that the cost of one control system facility is spread over a number of RPV programs, and control laws can be changed quickly as required, without changing the flight hardware. The remotely augmented vehicle concept is described, and flight test results from a subscale F-15 program are discussed. Suggestions of how the concept could lead to more effective testing of RPV control system concepts, and how it is applicable to a military RPV reconnaissance mission are given.

Deets, D. A.↗
NASA NTRS1984

Testing relativity with solar system dynamics

A major breakthrough is described in the accuracy of Solar System dynamical tests of relativistic gravity. The breakthrough was achieved by factoring in ranging data from Viking Landers 1 and 2 from the surface of Mars. Other key data sources included optical transit circle observations, lunar laser ranging, planetary radar, and spacecraft (Mariner 9 to Mars and Mariner 10 to Mercury). The Solar System model which is used to fit the data and the process by which such fits are performed are explained and results are discussed. The results are fully consistent with the predictions of General Relativity.

Hellings, R. W.↗
NASA NTRS1998

Statistical Treatment of Earth Observing System Pyroshock Separation Test Data

The Earth Observing System (EOS) AM-1 spacecraft for NASA's Mission to Planet Earth is scheduled to be launched on an Atlas IIAS vehicle in June of 1998. One concern is that the instruments on the EOS spacecraft are sensitive to the shock-induced vibration produced when the spacecraft separates from the launch vehicle. By employing unique statistical analysis to the available ground test shock data, the NASA Lewis Research Center found that shock-induced vibrations would not be as great as the previously specified levels of Lockheed Martin. The EOS pyroshock separation testing, which was completed in 1997, produced a large quantity of accelerometer data to characterize the shock response levels at the launch vehicle/spacecraft interface. Thirteen pyroshock separation firings of the EOS and payload adapter configuration yielded 78 total measurements at the interface. The multiple firings were necessary to qualify the newly developed Lockheed Martin six-hardpoint separation system. Because of the unusually large amount of data acquired, Lewis developed a statistical methodology to predict the maximum expected shock levels at the interface between the EOS spacecraft and the launch vehicle. Then, this methodology, which is based on six shear plate accelerometer measurements per test firing at the spacecraft/launch vehicle interface, was used to determine the shock endurance specification for EOS. Each pyroshock separation test of the EOS spacecraft simulator produced its own set of interface accelerometer data. Probability distributions, histograms, the median, and higher order moments (skew and kurtosis) were analyzed. The data were found to be lognormally distributed, which is consistent with NASA pyroshock standards. Each set of lognormally transformed test data produced was analyzed to determine if the data should be combined statistically. Statistical testing of the data's standard deviations and means (F and t testing, respectively) determined if data sets were significantly different at a 95-percent confidence level. If two data sets were found to be significantly different, these families of data were not combined for statistical purposes. This methodology produced three separate statistical data families of shear plate data. For each population, a P99.1/50 (probability/confidence) per-separation-nut firing level was calculated. By using the binomial distribution, Lewis researchers determined that this pernut firing level was equivalent to a P95/50 per-flight confidence level. The overall envelope of the per-flight P95/50 levels led to Lewis' recommended EOS interface shock endurance specification. A similar methodology was used to develop Lewis' recommended EOS mission assurance levels. The available test data for the EOS mission are significantly larger than for a normal mission, thus increasing the confidence level in the calculated expected shock environment. Lewis significantly affected the EOS mission by properly employing statistical analysis to the data. This analysis prevented a costly requalification of the spacecraft's instruments, which otherwise would have been exposed to significantly higher test levels.

McNelis, Anne M.↗
NASA NTRS1980

Shuttle orbiter Ku-band radar/communications system design evaluation

Tasks performed in an examination and critique of a Ku-band radar communications system for the shuttle orbiter are reported. Topics cover: (1) Ku-band high gain antenna/widebeam horn design evaluation; (2) evaluation of the Ku-band SPA and EA-1 LRU software; (3) system test evaluation; (4) critical design review and development test evaluation; (5) Ku-band bent pipe channel performance evaluation; (6) Ku-band LRU interchangeability analysis; and (7) deliverable test equipment evaluation. Where discrepancies were found, modifications and improvements to the Ku-band system and the associated test procedures are suggested.

Dodds, J.↗
NASA NTRS1980

Shuttle communication systems compatibility and performance tests

The compatibility and performance of the Shuttle communications system must be certified prior to operational missions. For this purpose, NASA has established the Electronics Systems Test Laboratory (ESTL) at the Johnson Space Center. This paper discusses the Shuttle communications system compatibility and performance testing being performed in the ESTL. The ESTL system verification test philosophy, including capabilities, procedures, and unique testing equipment are summarized. Summaries of the significant results of compatibility and performance tests of the Orbiter/Space-flight Tracking and Data Network, Orbiter/Air Force Remote Tracking Station, Orbiter/Tracking and Data Relay Satellite System and Orbiter/Shuttle Launch Support System interfaces are presented. The ESTL's unique ability to locate potential communication problems and participate in the resolution of these problems are discussed in detail.

Bromley, L. K.↗
NASA NTRS1992

The Development of an Airborne Information Management System for Flight Test

An airborne information management system is being developed at the NASA Dryden Flight Research Facility. This system will improve the state of the art in management data acquisition on-board research aircraft. The design centers around highly distributable, high-speed microprocessors that allow data compression, digital filtering, and real-time analysis. This paper describes the areas of applicability, approach to developing the system, potential for trouble areas, and reasons for this development activity. System architecture (including the salient points of what makes it unique), design philosophy, and tradeoff issues are also discussed.

Flight Testing↗