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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 1,693 records · Page 94
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Sonic-boom measurements for SR-71 aircraft operating at Mach numbers to 3.0 and altitudes to 24384 meters

Sonic-boom pressure signatures produced by the SR-71 aircraft at altitudes from 10,668 to 24,384 meters and Mach numbers 1.35 to 3.0 were obtained as an adjunct to the sonic boom evaluation program relating to structural and subjective response which was conducted in 1966-1967 time period. Approximately 2000 sonic-boom signatures from 33 flights of the SR-71 vehicle and two flights of the F-12 vehicle were recorded. Measured ground-pressure signatures for both on-track and lateral measuring station locations are presented and the statistical variations of the overpressure, positive impulse, wave duration, and shock-wave rise time are illustrated.

Maglieri, D. J.↗
NASA NTRS1971

Sector structure of the solar magnetic field.

Analysis of the solar sector structure, which consists of a boundary in the north-south direction such that on one side of the boundary the large-scale weak photospheric magnetic field is predominantly directed out of the sun, and on the other side of the field this boundary is directed into the sun. The region westward of a solar sector boundary tends to be unusually quiet and the region eastward of a solar sector boundary tends to be unusually active. The tendency is discussed with reference to flares, coronal enhancements, plage structure, and geomagnetic response.

Wilcox, J. M.↗
NASA NTRS1972

Aluminium. II - A review of deformation properties of high purity aluminium and dilute aluminium alloys.

The elastic and plastic deformation behavior of high-purity aluminum and of dilute aluminum alloys is reviewed. Reliable property data, including elastic moduli, elastic coefficients, tensile, creep, fatigue, hardness, and impact are presented. Single crystal tensile results are discussed. Rather comprehensive reference lists, containing publications of the past 20 years, are included for each of the above categories. Defect structures and mechanisms responsible for mechanical behavior are presented. Strengthening techniques (alloys, cold work, irradiation, quenching, composites) and recovery are briefly reviewed.

Reed, R. P.↗
NASA NTRS1972

NERVA dynamic analysis methodology, SPRVIB

The general dynamic computer code called SPRVIB (Spring Vib) developed in support of the NERVA (nuclear engine for rocket vehicle application) program is described. Using normal mode techniques, the program computes kinematical responses of a structure caused by various combinations of harmonic and elliptic forcing functions or base excitations. Provision is made for a graphical type of force or base excitation input to the structure. A description of the required input format and a listing of the program are presented, along with several examples illustrating the use of the program. SPRVIB is written in FORTRAN 4 computer language for use on the CDC 6600 or the IBM 360/75 computers.

Vronay, D. F.↗
NASA NTRS1973

Development of low-shock pyrotechnic separation nuts

Performance demonstrations and comparisons were made on six flight type pyrotechnic separation nut designs, two of which are standard designs in current use, and four of which were designed to produce low shock on actuation. Although the shock performances of the four low shock designs are considerably lower than the standard designs, some penalties may be incurred in increased volume, weight, or complexity. These nuts, and how they are installed, can significantly influence the pyrotechnic shock created in spacecraft structures. A high response monitoring system has been developed and demonstrated to provide accurate performance comparisons for pyrotechnic separation nuts.

Bement, L. J.↗
NASA NTRS1973

Glauber-theory approach for molecular vibrational excitations

Molecular vibrational excitations by charged-particle impact are investigated within the Glauber-theory approach. Theoretical results for electron-H2 scattering give good agreement with experimental data. We study the physical effects responsible for the structures in the differential cross section.

Chang, T. N.↗
NASA NTRS1974

The 3.3K thrust chamber life prediction

The cause of low-cycle fatigue failure of the 3.3K Thrust Chamber was investigated. This thrust chamber typifies the current trend in rocket nozzle design which calls for high performance coupled with weight and volume limitations as well as the requirement of reusability. The analysis was performed with the BOPACE finite-element computer program which provides capability to determine viscoplastic response of a structure subjected to cyclic thermal and mechanical loading. Results are presented which show the critical region for low-cycle fatigue and the history of strain within that region for each thermo-mechanical loading cycle in the 3.3K thrust chamber. The predicted behavior was used to evaluate the low-cycle fatigue life near the throat plane of the chamber. The results show that BOPACE provides an extremely accurate prediction of structural behavior; the critical region was identified and the life determined from computed strains was within 154 cycles of the observed failure at 1013 cycles.

Armstrong, W. H.↗
NASA NTRS1975

Comparison of vibrations of a combination of solid-rocket launch vehicle and payload during a ground firing and launching

The results of a study into the environmental vibrations of a payload mounted on the Nike rocket launch vehicle were presented. Data were obtained during the flight acceptance test of the payload, the firing of the total vehicle in a special test stand, and the powered and unpowered flights of the vehicle. The vibrational response of the structure was measured. Data were also obtained on the fluctuating pressure on the outside surface of the vehicle and inside the forward and after ends of the rocket chamber. A comparison of the data from the three test conditions indicated that external pressure fluctuations were the major source of vibrations in the payload area, and pressure fluctuations within the rocket motor were the major source of vibrations contiguous to the payload area.

Schoenster, J. A.↗
NASA NTRS1976

Overview of the NASA high power laser program

The overall objectives of the NASA High Power Laser Program are reviewed along with their structure and center responsibilities. Present and future funding, laser power transmission in space, selected program highlights, the research and technology schedule, and the expected pace of the program are briefly considered.

Lundholm, J. G.↗
NASA NTRS1976

The VORCOM. Part 1: Analytical considerations

The analytical considerations which support the computation of (1) two components of the velocity vector from an X-array and (2) the transverse vorticity from the X-array and an adjacent parallel wire pair are presented. The electronic circuit which will execute these computations at a 50 khz rate is also described. The factors limiting the accuracy of the measurements are identified and quantitative estimates are given for a typical x-probe. An extensive analysis of the factors which effect the output and which are unknown (or unknowable) during the measurements is presented. Quantitative estimates of these effects are developed in the form of an uncertainty analysis. Numerical values, calculated using the analytical structure of the response equations, are tabulated; other estimates which require special experiments are described.

Foss, J. F.↗
NASA NTRS1975

Physical characteristics of interplanetary space

The Sun The properties of interplanetary space are determined, to a considerable extent, by the central body of the solar system-the Sun which is the source of powerful streams of corpuscular and electromagnetic radiation, and is responsible for the structure of the interplanetary magnetic fields. Many phenomena on the Earth are closely related to processes occurring on the Sun. The mechanism of this relationship is not yet fully understood, but it is clear that the solar wind, the corpuscular streams, and short-wave electromagnetic radiation of the Sun play a prominent role in these processes. Before describing the manifestations of Sun-Earth relationships, the elements of solar activity should be discussed.

S. N. Vernov↗
NASA NTRS1976

An approach to the prediction of airplane interior noise

At present there is no well-proven method of calculating airplane interior noise associated with jet and boundary layer sources. In this presentation, statistical energy analysis is used to calculate fuselage skin vibration and interior noise levels, with the sidewall represented as a double-wall system. The results show that, in the case of an unpressurized fuselage, the acoustic transmission is dominated by the non-resonant response of the structure. Extension of the results to include pressurization effects and turbulent boundary layer excitation is discussed, particular emphasis being placed on aerodynamic coincidence.

Wilby, J. F.↗
NASA NTRS1977

Anthropomorphic master/slave manipulator system

An anthropomorphic master/slave manipulator system including master arm apparatus with a plurality of master tubular articulated portions is outlined. Objectives of this investion were to provide a system that accurately and smoothly simulates human limb movement at a remote location. The system has a high frequency response, a high structural stiffness and a design that protects the components of the slave mechanism. Simulation of human movements is possible in outer space, underwater, and in a hazardous environment such as in a high radiation area. The equivalent ability, dexterity, and strength of a human arm are simulated.

Vykukal, H. C.↗
NASA NTRS1978

Heat Transfer and Fluid Mechanics Institute, Meeting, 26th, Washington State University, Pullman, Wash., June 26-28, 1978, Proceedings

Papers are presented on the heat transfer and fluid mechanics in energy systems including diesel combustion analysis using rapid sampling and the numerical simulation of thermal response of architectural structures. Experiments associated with hypersonic boundary layers, the prediction of nozzle-wall pressure distribution, and the effects of nozzle geometry on an axisymmetric thrust augmentor are outlined. Predictions are made of film thickness on a roll-metering device and the thermal characteristics of multiple-surface submerged condenser modules are described. Numerical studies are made of the interaction between natural and forced convection in a complex geometry and of pressure drop and holdup in two-phase stratified flow. A numerical solution is given for viscous flows at high Reynolds numbers and for compressible boundary layer flows near separation or reattachment. The structure and transport properties in turbulent shear flows are reviewed along with the spectra of Reynolds stresses in a developing pipe flow.

Crowe, C. T.↗
NASA NTRS1978

Improved aircraft dynamic response and fatigue life during ground operations using an active control landing gear system

A three-degree-of-freedom aircraft landing analysis incorporating a series-hydraulic active control main landing gear has been developed and verified using preliminary experimental data from drop tests of a modified main landing gear from a 2722 kg (6000 lbm) class of airplane. The verified analysis was also employed to predict the landing dynamics of a supersonic research airplane with an active control main landing gear system. The results of this investigation have shown that this type of active gear is feasible and indicate a potential for improving airplane dynamic response and reducing structural fatigue damage during ground operations by approximately 90% relative to that incurred with the passive gear.

Mcgehee, J. R.↗
NASA NTRS1979

Field-aligned currents, convection electric fields, and ULF-ELF waves in the cusp

Nearly simultaneous observations from the Triad and Hawkeye satellites over the Southern Hemisphere, at low altitudes near the noon meridian and close to the usual polar cusp latitudes, show that in and near the polar cusp there exist several relationships between field-aligned currents (FACs), convection electric fields, ULF-ELF magnetic noise, broadband electrostatic noise and interplanetary magnetic fields. The most important findings are (1) the FACs directed into the ionosphere in the noon-to-dusk local time sector and directed away from the ionosphere in the noon-to-dawn local time sector and identified as region-1 permanent FACs (Iijima and Potemra, 1976a) and are located equatorward of the regions of antisunward (westward) convection; (2) the observations are consistent with a two-cell convection pattern symmetric in one case (throat positioned at noon) and asymmetric in another (throat located in a sector on the forenoon side in juxtaposition to the region of strong convection on the afternoon side); and (3) fine-structure FACs are responsible for the generation of ULF-ELF noise in the polar cusp.

Saflekos, N. A.↗
NASA NTRS1981

Langley Research Center contributions in advancing active control technology

The application of active control technology to reduce aeroelastic response of aircraft structures offers a potential for significant payoffs in terms of aerodynamic efficiency and weight savings. Some of the contributions of the Langley Research Center in advancing active control technology are described. Contributions are categorized into the development of appropriate analysis tools, control law synthesis methodology, and experimental investigations aimed at verifying both analysis and synthesis methodology.

Abel, I.↗
NASA NTRS1981

Overview of Langley activities in active controls research

The application of active controls technology to reduce aeroelastic response of aircraft structures offers a potential for significant payoffs in terms of aerodynamic efficiency and weight savings. The activities of the Langley Research Center (laRC) in advancing active controls technology. Activities are categorized into the development of appropriate analysis tools, control law synthesis methodology, and experimental investigations aimed at verifying both analysis and synthesis methodology.

Abel, I.↗