Wind-Tunnel Sonic-Boom Testing Techniques
Wind tunnel tests of sonic boom phenomena, noting weak pressure field measurement, construction of extremely small models, boundary layer effects, etc
TEST METHOD↗
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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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Inlet-engine-nozzle wind tunnel test techniques
Wind tunnel tests of supersonic propulsion inlet, engine and exhaust nozzles
Bowditch, D. N.↗
High temperature ground vibration test techniques
This paper describes the experimental modal test techniques and procedures used to conduct uniform, nonuniform, and transient thermoelastic vibration tests. Experimental setup and elevated temperature instrumentation considerations are also discussed. Modal data for a 30.48- by 127-cm aluminum plate heated to a temperature of 371.1 C are presented. These data show the effect of heat on the plate's modal characteristics.
Kehoe, Michael W.↗
Flight test techniques for wake-vortex minimization studies
Flight test techniques developed for use in a study of wake turbulence and used recently in flight studies of wake minimization methods are discussed. Flow visualization was developed as a technique for qualitatively assessing minimization methods and is required in flight test procedures for making quantitative measurements. The quantitative techniques are the measurement of the upset dynamics of an aircraft encountering the wake and the measurement of the wake velocity profiles. Descriptions of the instrumentation and the data reduction and correlation methods are given.
Jacobsen, R. A.↗
Nondestructive testing techniques for multilayer printed wiring boards.
Nondestructive testing techniques for multilayer printed wiring boards stressing axial transverse laminography and mutual coupling
NONDESTRUCTIVE TESTING↗
A review of recent developments in flight test techniques at the Ames Research Center, Dryden Flight Research Facility
New flight test techniques in use at Ames Dryden are reviewed. The use of the pilot in combination with ground and airborne computational capabilities to maximize data return is discussed, including the remotely piloted research vehicle technique for high-risk testing, the remotely augmented vehicle technique for handling qualities research, and use of ground computed flight director information to fly unique profiles such as constant Reynolds number profiles through the transonic flight regime. Techniques used for checkout and design verification of systems-oriented aircraft are discussed, including descriptions of the various simulations, iron bird setups, and vehicle tests. Some newly developed techniques to support the aeronautical research disciplines are discussed, including a new approach to position-error determination, and the use of a large skin friction balance for the measurement of drag caused by various excrescencies.
Layton, G. P.↗
A test technique for measuring lightning-induced voltages on aircraft electrical circuits
The development of a test technique used for the measurement of lightning-induced voltages in the electrical circuits of a complete aircraft is described. The resultant technique utilizes a portable device known as a transient analyzer capable of generating unidirectional current impulses similar to lightning current surges, but at a lower current level. A linear relationship between the magnitude of lightning current and the magnitude of induced voltage permitted the scaling up of measured induced values to full threat levels. The test technique was found to be practical when used on a complete aircraft.
Walko, L. C.↗
High-alpha flight dynamics research on the X-29 configuration using dynamic model test techniques
High-angle-of-attack flight dynamics of the X-29 configuration were studied using dynamic model test techniques. These tests identified phenomena including wing rock, spins, and tumbling which dominate the high-alpha behavior of the configuration and define its usable flight envelope. Results of these tests have been used to design flight control concepts to minimize adverse behavior. Planned high-angle-of-attack flight tests of the X-29 airplane will provide an opportunity to validate the model predictions.
Croom, Mark A.↗
Hardness Assurance and Testing Techniques for High Resolution (12- to 16-bit) Analog-to-Digital Converters
Discussed are hardness assurance and testing techniques to test and evaluate total dose radiation degradation of high resolution A/D converters. Because high-speed, high-resolution converters are critical parts in a digital signal processing or data acquisition system, the evaluation of performance in the early design phase is very important. Converters from three manufacturers are evaluated.
Analog-to-Digital↗
Comparison of Dynamic Stability Testing Techniques with Magnetic Suspension Wind Tunnel
Dynamic stability testing techniques currently utilized at NASA Langley Research Center (LaRC) are conducted in multiple facilities and consists of free flight, forced oscillation, and free-to-oscillate tests. The MIT/NASA/ODU Magnetic Suspension and Balance System (MSBS) has been recommissioned to explore its utility as an additional facility to expand the dynamic stability test capabilities currently available at NASA LaRC. Simulations were created to replicate each current test facility and method as closely as possible. Data collected from the simulated environments was corrupted with replicated noise sources of the different testing environments and then compared to real data collected during tests when such data was available. The corrupted data was then passed through data reduction and System Identification (SID) to estimate the accuracy of the results with the known aerodynamic model that was utilized within the simulation to generate the original data. Magnitudes of noise were varied utilizing Monte Carlo analysis to perform sensitivity analysis of each noise source on the extracted dynamic stability coefficients. Some preliminary results will be presented.
Otoniel Ramirez↗
Comparison of Dynamic Stability Testing Techniques with Magnetic Suspension Wind Tunnel
Dynamic stability testing techniques currently utilized at NASA Langley Research Center (LaRC) are conducted in multiple facilities and consists of free flight, forced oscillation, and free-to-oscillate tests. The MIT/NASA/ODU Magnetic Suspension and Balance System (MSBS) has been recommissioned to explore its utility as an additional facility to expand the dynamic stability test capabilities currently available at NASA LaRC. Simulations were created to replicate each current test facility and method as closely as possible. Data collected from the simulated environments was corrupted with replicated noise sources of the different testing environments and then compared to real data collected during tests when such data was available. The corrupted data was then passed through data reduction and System Identification (SID) to estimate the accuracy of the results with the known aerodynamic model that was utilized within the simulation to generate the original data. Magnitudes of noise were varied utilizing Monte Carlo analysis to perform sensitivity analysis of each noise source on the extracted dynamic stability coefficients. Some preliminary results will be presented.
Otoniel Ramirez↗
Nondestructive testing techniques for the detection of stress corrosion
Nondestructive testing techniques for detection of stress corrosion
Source record↗
Testing techniques for mechanical characterization of rapidly solidified materials
Mechanical property testing techniques are reviewed for rapidly solidified materials. Mechanical testing of rapidly solidified materials is complicated by the fact that in most cases at least one dimension of the material is very small (less than 100 microns). For some geometries, i.e., powder or thin surface layers, microhardness is the only feasible mechanical test. The ribbon geometry which is obtained by the melt-spinning method, however, has been used for a variety of mechanical property measurements including elastic properties, tensile properties, fracture toughness, creep, and fatigue. These techniques are described with emphasis placed on the precautions required by the restricted geometry of rapidly solidified specimens.
Koch, C. C.↗
In-flight acoustic testing techniques using the YO-3A Acoustic Research Aircraft
This report discusses the flight testing techniques and equipment employed during air-to-air acoustic testing of helicopters at Ames Research Center. The in flight measurement technique used enables acoustic data to be obtained without the limitations of anechoic chambers or the multitude of variables encountered in ground based flyover testing. The air-to-air testing is made possible by the NASA YO-3A Acoustic Research Aircraft. This "Quiet Aircraft' is an acoustically instrumented version of a quiet observation aircraft manufactured for the military. To date, tests with the following aircraft have been conducted: YO-3A background noise; Hughes 500D; Hughes AH-64; Bell AH-1S; Bell AH-1G. Several system upgrades are being designed and implemented to improve the quality of data. This report will discuss not only the equipment involved and aircraft tested, but also the techniques used in these tests. In particular, formation flying position locations, and the test matrices will be discussed. Examples of data taken will also be presented.
Cross, J. L.↗
In-flight acoustic testing techniques using the YO-3A acoustic research aircraft
This report discusses the flight testing techniques and equipment employed during air-to-air acoustic testing of helicopters at Ames Research Center. The in-flight measurement technique used enables acoustic data to be obtained without the limitations of anechoic chambers or the multitude of variables encountered in ground based flyover testing. The air-to-air testing is made possible by the NASA YO-3A Acoustic Research Aircraft. This 'Quiet Aircraft' is an acoustically instrumented version of a quiet observation aircraft manufactured for the military. To date, tests with the following aircraft have been conducted: YO-3A background noise; Hughes 500D; Hughes AH-64; Bell AH-1S; Bell AH-1G. Several system upgrades are being designed and implemented to improve the quality of data. This report will discuss not only the equipment involved and aircraft tested, but also the techniques used in these tests. In particular, formation flying, position locations, and the test matrices will be discussed. Examples of data taken will also be presented.
Cross, J. L.↗
Flight control system design factors for applying automated testing techniques
The principal design features and operational experiences of the X-29 forward-swept-wing aircraft and F-18 high alpha research vehicle (HARV) automated test systems are discussed. It is noted that operational experiences in developing and using these automated testing techniques have highlighted the need for incorporating target system features to improve testability. Improved target system testability can be accomplished with the addition of nonreal-time and real-time features. Online access to target system implementation details, unobtrusive real-time access to internal user-selectable variables, and proper software instrumentation are all desirable features of the target system. Also, test system and target system design issues must be addressed during the early stages of the target system development. Processing speeds of up to 20 million instructions/s and the development of high-bandwidth reflective memory systems have improved the ability to integrate the target system and test system for the application of automated testing techniques. It is concluded that new methods of designing testability into the target systems are required.
Sitz, Joel R.↗
A novel triaxial vibration test technique
The present work examines the circumstances under which simultaneous multiaxial vibration testing may be desirable, the testing techniques and equipment required to make it feasible, and the type of results that may be obtained together with some practical limitations to the techniques. Two schemes for performing vibration testing simultaneously or sequentially along three mutually perpendicular axes are considered and the most promising, involving a 'floating' technique, is presented in some detail. Practical problems associated with jig design and system resonances, cross-coupling between the various degrees of freedom, secondary loads on shaker elements, and system drift, are considered and workable solutions proposed. A simple simulation of multiaxial testing of a 1.1-pound inertia-simulated model of an Apollo command module is presented.
Wignot, J. E.↗
Study of space battery accelerated testing techniques. Phase 1 report. Survey of testing methods applicable to space battery evaluation
Testing methods applicable to space battery evaluation - literature survey
Brooman, E. W.↗