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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 451 records · Page 25
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NASA NTRS2004

Flight Test Results for the F-16XL With a Digital Flight Control System

In the early 1980s, two F-16 airplanes were modified to extend the fuselage length and incorporate a large area delta wing planform. These two airplanes, designated the F-16XL, were designed by the General Dynamics Corporation (now Lockheed Martin Tactical Aircraft Systems) (Fort Worth, Texas) and were prototypes for a derivative fighter evaluation program conducted by the United States Air Force. Although the concept was never put into production, the F-16XL prototypes provided a unique planform for testing concepts in support of future high-speed supersonic transport aircraft. To extend the capabilities of this testbed vehicle the F-16XL ship 1 aircraft was upgraded with a digital flight control system. The added flexibility of a digital flight control system increases the versatility of this airplane as a testbed for aerodynamic research and investigation of advanced technologies. This report presents the handling qualities flight test results covering the envelope expansion of the F-16XL with the digital flight control system.

Stachowiak, Susan J.↗
NASA NTRS2008

Automatic Testcase Generation for Flight Software

The TacSat3 project is applying Integrated Systems Health Management (ISHM) technologies to an Air Force spacecraft for operational evaluation in space. The experiment will demonstrate the effectiveness and cost of ISHM and vehicle systems management (VSM) technologies through onboard operation for extended periods. We present two approaches to automatic testcase generation for ISHM: 1) A blackbox approach that views the system as a blackbox, and uses a grammar-based specification of the system's inputs to automatically generate *all* inputs that satisfy the specifications (up to prespecified limits); these inputs are then used to exercise the system. 2) A whitebox approach that performs analysis and testcase generation directly on a representation of the internal behaviour of the system under test. The enabling technologies for both these approaches are model checking and symbolic execution, as implemented in the Ames' Java PathFinder (JPF) tool suite. Model checking is an automated technique for software verification. Unlike simulation and testing which check only some of the system executions and therefore may miss errors, model checking exhaustively explores all possible executions. Symbolic execution evaluates programs with symbolic rather than concrete values and represents variable values as symbolic expressions. We are applying the blackbox approach to generating input scripts for the Spacecraft Command Language (SCL) from Interface and Control Systems. SCL is an embedded interpreter for controlling spacecraft systems. TacSat3 will be using SCL as the controller for its ISHM systems. We translated the SCL grammar into a program that outputs scripts conforming to the grammars. Running JPF on this program generates all legal input scripts up to a prespecified size. Script generation can also be targeted to specific parts of the grammar of interest to the developers. These scripts are then fed to the SCL Executive. ICS's in-house coverage tools will be run to measure code coverage. Because the scripts exercise all parts of the grammar, we expect them to provide high code coverage. This blackbox approach is suitable for systems for which we do not have access to the source code. We are applying whitebox test generation to the Spacecraft Health INference Engine (SHINE) that is part of the ISHM system. In TacSat3, SHINE will execute an on-board knowledge base for fault detection and diagnosis. SHINE converts its knowledge base into optimized C code which runs onboard TacSat3. SHINE can translate its rules into an intermediate representation (Java) suitable for analysis with JPF. JPF will analyze SHINE's Java output using symbolic execution, producing testcases that can provide either complete or directed coverage of the code. Automatically generated test suites can provide full code coverage and be quickly regenerated when code changes. Because our tools analyze executable code, they fully cover the delivered code, not just models of the code. This approach also provides a way to generate tests that exercise specific sections of code under specific preconditions. This capability gives us more focused testing of specific sections of code.

Bushnell, David Henry↗
NASA NTRS2009

Wind Tunnel Test of the SMART Active Flap Rotor

Boeing and a team from Air Force, NASA, Army, DARPA, MIT, UCLA, and U. of Maryland have successfully completed a wind-tunnel test of the smart material actuated rotor technology (SMART) rotor in the 40- by 80-foot wind-tunnel of the National Full-Scale Aerodynamic Complex at NASA Ames Research Center. The Boeing SMART rotor is a full-scale, five-bladed bearingless MD 900 helicopter rotor modified with a piezoelectric-actuated trailing edge flap on each blade. The eleven-week test program evaluated the forward flight characteristics of the active-flap rotor at speeds up to 155 knots, gathered data to validate state-of-the-art codes for rotor aero-acoustic analysis, and quantified the effects of open and closed loop active flap control on rotor loads, noise, and performance. The test demonstrated on-blade smart material control of flaps on a full-scale rotor for the first time in a wind tunnel. The effectiveness of the active flap control on noise and vibration was conclusively demonstrated. Results showed significant reductions up to 6dB in blade-vortex-interaction and in-plane noise, as well as reductions in vibratory hub loads up to 80%. Trailing-edge flap deflections were controlled within 0.1 degrees of the commanded value. The impact of the active flap on control power, rotor smoothing, and performance was also demonstrated. Finally, the reliability of the flap actuation system was successfully proven in more than 60 hours of wind-tunnel testing.

Straub, Friedrich K.↗
NASA NTRS2010

Altitude Testing of Large Liquid Propellant Engines

The National Aeronautics and Space Administration entered a new age on January 14, 2004 with President Bush s announcement of the creation the Vision for Space Exploration that will take mankind back to the Moon and on beyond to Mars. In January, 2006, after two years of hard, dedicated labor, engineers within NASA and its contractor workforce decided that the J2X rocket, based on the heritage of the Apollo J2 engine, would be the new engine for the NASA Constellation Ares upper stage vehicle. This engine and vehicle combination would provide assured access to the International Space Station to replace that role played by the Space Shuttle and additionally, would serve as the Earth Departure Stage, to push the Crew Excursion Vehicle out of Earth Orbit and head it on a path for rendezvous with the Moon. Test as you fly, fly as you test was chosen to be the guiding philosophy and a pre-requisite for the engine design, development, test and evaluation program. An exhaustive survey of national test facility assets proved the required capability to test the J2X engine at high altitude for long durations did not exist so therefore, a high altitude/near space environment testing capability would have to be developed. After several agency concepts the A3 High Altitude Testing Facility proposal was selected by the J2X engine program on March 2, 2007 and later confirmed by a broad panel of NASA senior leadership in May 2007. This facility is to be built at NASA s John C. Stennis Space Center located near Gulfport, Mississippi. 30 plus years of Space Shuttle Main Engine development and flight certification testing makes Stennis uniquely suited to support the Vision For Space Exploration Return to the Moon. Propellant handling infrastructure, engine assembly facilities, a trained and dedicated workforce and a broad and varied technical support base will all ensure that the A3 facility will be built on time to support the schedule needs of the J2X engine and the ultimate flight of the first Ares I vehicle. The A3 facility will be able to simulate pre-ignition altitude from sea-level to 100,000 feet and maintain it up to 650 seconds. Additionally the facility will be able to accommodate initial ignition, shutdown and then restart test profiles. A3 will produce up to 5000 lbm/sec of superheated steam utilizing a Chemical Steam generation system. Two separate inline steam ejectors will be used to produce a test cell vacuum to simulate the 100,000 ft required altitude. Operational capability will ensure that the facility can start up and shutdown without producing adverse pressure gradients across the J2X nozzle. The facility will have a modern thrust measurement system for accurate determination of engine performance. The latest advances in data acquisition and control will be incorporated to measure performance parameters during hotfire testing. Provisions are being made in the initial design of the new altitude facility to allow for testing of other, larger engines and potential upper stage launch vehicles that might require vacuum start testing of the engines. The new facility at Stennis Space Center will be complete and ready for hotfire operations in late 2010.

Maynard, Bryon T.↗
NASA NTRS2011

Measured Sonic Boom Signatures Above and Below the XB-70 Airplane Flying at Mach 1.5 and 37,000 Feet

During the 1966-67 Edwards Air Force Base (EAFB) National Sonic Boom Evaluation Program, a series of in-flight flow-field measurements were made above and below the USAF XB-70 using an instrumented NASA F-104 aircraft with a specially designed nose probe. These were accomplished in the three XB-70 flights at about Mach 1.5 at about 37,000 ft. and gross weights of about 350,000 lbs. Six supersonic passes with the F-104 probe aircraft were made through the XB-70 shock flow-field; one above and five below the XB-70. Separation distances ranged from about 3000 ft. above and 7000 ft. to the side of the XB-70 and about 2000 ft. and 5000 ft. below the XB-70. Complex near-field "sawtooth-type" signatures were observed in all cases. At ground level, the XB-70 shock waves had not coalesced into the two-shock classical sonic boom N-wave signature, but contained three shocks. Included in this report is a description of the generating and probe airplanes, the in-flight and ground pressure measuring instrumentation, the flight test procedure and aircraft positioning, surface and upper air weather observations, and the six in-flight pressure signatures from the three flights.

Maglieri, Domenic J.↗
NASA NTRS2006

Using Apex To Construct CPM-GOMS Models

process for automatically generating computational models of human/computer interactions as well as graphical and textual representations of the models has been built on the conceptual foundation of a method known in the art as CPM-GOMS. This method is so named because it combines (1) the task decomposition of analysis according to an underlying method known in the art as the goals, operators, methods, and selection (GOMS) method with (2) a model of human resource usage at the level of cognitive, perceptual, and motor (CPM) operations. CPM-GOMS models have made accurate predictions about behaviors of skilled computer users in routine tasks, but heretofore, such models have been generated in a tedious, error-prone manual process. In the present process, CPM-GOMS models are generated automatically from a hierarchical task decomposition expressed by use of a computer program, known as Apex, designed previously to be used to model human behavior in complex, dynamic tasks. An inherent capability of Apex for scheduling of resources automates the difficult task of interleaving the cognitive, perceptual, and motor resources that underlie common task operators (e.g., move and click mouse). The user interface of Apex automatically generates Program Evaluation Review Technique (PERT) charts, which enable modelers to visualize the complex parallel behavior represented by a model. Because interleaving and the generation of displays to aid visualization are automated, it is now feasible to construct arbitrarily long sequences of behaviors. The process was tested by using Apex to create a CPM-GOMS model of a relatively simple human/computer-interaction task and comparing the time predictions of the model and measurements of the times taken by human users in performing the various steps of the task. The task was to withdraw $80 in cash from an automated teller machine (ATM). For the test, a Visual Basic mockup of an ATM was created, with a provision for input from (and measurement of the performance of) the user via a mouse. The times predicted by the automatically generated model turned out to approximate the measured times fairly well (see figure). While these results are promising, there is need for further development of the process. Moreover, it will also be necessary to test other, more complex models: The actions required of the user in the ATM task are too sequential to involve substantial parallelism and interleaving and, hence, do not serve as an adequate test of the unique strength of CPM-GOMS models to accommodate parallelism and interleaving.

John, Bonnie↗
NASA NTRS2012

Development and Testing of a Sorbent-Based Atmosphere Revitalization System 2010/2011

Spacecraft being developed for future exploration missions incorporate Environmental Control and Life Support Systems (ECLSS) that limit weight, power, and volume thus requiring systems with higher levels of efficiency while maintaining high dependability and robustness. For air revitalization, an approach that meets those goals utilizes a regenerative Vacuum-Swing Adsorption (VSA) system that removes 100% of the CO2 from the cabin atmosphere as well as 100% of the water. A Sorbent Based Atmosphere Revitalization (SBAR) system is a VSA system that utilizes standard commercial adsorbents that have been proven effective and safe in spacecraft including Skylab and the International Space Station. The SBAR system is the subject of a development, test, and evaluation program that is being conducted at NASA s Marshall Space Flight Center. While previous testing had validated that the technology is a viable option, potential improvements to system design and operation were identified. Modifications of the full-scale SBAR test articles and adsorption cycles have been implemented and have shown significant performance gains resulting in a decrease in the consumables required for a mission as well as improved mission safety. Previous testing had utilized single bed test articles, during this period the test facility was enhanced to allow testing on the full 2-bed SBAR system. The test facility simulates a spacecraft ECLSS and allows testing of the SBAR system over the full range of operational conditions using mission simulations that assess the real-time performance of the SBAR system during scenarios that include the metabolic transients associated with extravehicular activity. Although future manned missions are currently being redefined, the atmosphere revitalization requirements for the spacecraft are expected to be quite similar to the Orion and the Altair vehicles and the SBAR test program addressed validation to the defined mission requirements as well as operation in other potential vehicle architectures. The development program, including test articles, the test facility, and tests and results through early 2011 is discussed.

Miller, Lee A.↗
NASA NTRS2015

Summary of Liquid Oxygen/Hydrogen, Direct Metal Laser Sintering Injector Testing and Evaluation Effort at Marshall Space Flight Center

The last several years have witnessed a significant advancement in the area of additive manufacturing technology. One area that has seen substantial expansion in application has been laser sintering (or melting) in a powder bed. This technology is often termed 3D printing or various acronyms that may be industry, process, or company specific. Components manufactured via 3D printing have the potential to significantly reduce development and fabrication time and cost. The usefulness of 3D printed components is influenced by several factors such as material properties and surface roughness. This paper details three injectors that were designed, fabricated, and tested in order to evaluate the utility of 3D printed components for rocket engine applications. The three injectors were tested in a hot‐fire environment with chamber pressures of approximately 1400 psia. One injector was a 28 element design printed by Directed Manufacturing. The other two injectors were identical 40 element designs printed by Directed Manufacturing and Solid Concepts. All the injectors were swirl‐coaxial designs and were subscale versions of a full‐scale injector currently in fabrication. The test and evaluation programs for the 28 element and 40 element injectors provided a substantial amount of data that confirms the feasibility of 3D printed parts for future applications. The operating conditions of previously tested, conventionally manufactured injectors were reproduced in the 28 and 40 element programs in order to contrast the performance of each. Overall, the 3D printed injectors demonstrated comparable performance to the conventionally manufactured units. The design features of the aforementioned injectors can readily be implemented in future applications with a high degree of confidence.

Barnett, Gregory↗
NASA NTRS1972

The NASA-USPHS Health Evaluation and Enhancement Program

An exercise program was initiated to assess the feasibility of an on the job health evaluation and enhancement program, as well as to identify the factors which influenced volunteering, adherence, and effectiveness of the program. The program was utilized by 237 of the 998 eligible Federal employees, with a mean attendance of 1.3 days per week. Those who volunteered perceived a need for increased physical activity, felt they had sufficient time to participate, and derived subjective as well as objective benefits. Significant improvements were found in heart rate response to the standard exercise test, body weight, skinfold measurements, and triglycerides. A consistent relationship was found between subjectively reported effects of the program on work, health habits, and behavior, and improvement in cardiovascular function, based on treadmill performance. Numerous personal and programmatic factors influencing volunteering and participation were identified.

Durbeck, D. C.↗
NASA NTRS1990

Evaluation of NASA space grant consortia programs

The meaningful evaluation of the NASA Space Grant Consortium and Fellowship Programs must overcome unusual difficulties: (1) the program, in its infancy, is undergoing dynamic change; (2) the several state consortia and universities have widely divergent parochial goals that defy a uniform evaluative process; and (3) the pilot-sized consortium programs require that the evaluative process be economical in human costs less the process of evaluation comprise the effectiveness of the programs they are meant to assess. This paper represents an attempt to assess the context in which evaluation is to be conducted, the goals and limitations inherent to the evaluation, and to recommend appropriate guidelines for evaluation.

Eisenberg, Martin A.↗
NASA NTRS1977

Solar power satellite 50 kW VKS-7773 cw klystron evaluation

A test program for evaluating the electrical characteristics of a cw, 50 kW power output klystron at 2.45 GHz is described. The tube tested was an 8-cavity klystron, the VKS-7773 which had been in storage for seven years. Tests included preliminary testing of the tube, cold tests of microwave components, tests of the electromagnet, and first and second hot tests of the tube. During the second hot test, the tuner in the fifth cavity went down to air, preventing any further testing. Cause of failure is not known, and recommendations are to repair and modify the tube, then proceed with testing as before to meet program objectives.

Larue, A. D.↗
NASA NTRS1995

Evaluation metrics of educational programs for teachers

A system for evaluating the teacher programs and services in the Education Services Branch was developed. The primary stakeholder was interested in determining the worth or usefulness of these services to educators. Therefore, two instruments were developed to collect the data. One questionnaire was administered. Data was collected, analyzed and reported. The other questionnaire was pilot tested and will be administered to teachers during the school year.

Mitchell, Gwendolyn D.↗
NASA NTRS1975

SEASAT economic assessment. Volume 10: The SATIL 2 program (a program for the evaluation of the costs of an operational SEASAT system as a function of operational requirements and reliability

The SATIL 2 computer program was developed to assist with the programmatic evaluation of alternative approaches to establishing and maintaining a specified mix of operational sensors on spacecraft in an operational SEASAT system. The program computes the probability distributions of events (i.e., number of launch attempts, number of spacecraft purchased, etc.), annual recurring cost, and present value of recurring cost. This is accomplished for the specific task of placing a desired mix of sensors in orbit in an optimal fashion in order to satisfy a specified sensor demand function. Flow charts are shown, and printouts of the programs are given.

Source record↗
NASA NTRS1973

A highly efficient error analysis program for the evaluation of spacecraft tests of general relativity with application to solar probes

A computer program is described which can be used to study the feasibility of conducting relativity experiments on a wide range of hypothetical space missions, and a few applications are presented for solar probes which approach the Sun within 0.25 to 0.35 AU. It is assumed that radio ranging data are available from these spacecraft, and that accuracies on the order of 15 meters can be achieved. This is compatible with current accuracies of ranging to Mariner spacecraft. At this level of accuracy, the range data are sensitive to a number of effects, and for this reason it has been necessary to include a total of up to 23 parameters in the feasibility studies, even though there are only two parameters of real interest in the relativity experiments.

Anderson, J. D.↗