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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 289 records · Page 16
All sourcesNASA NTRSDOE OSTI
NASA NTRS1976

Full-scale crash test of a CH-47C helicopter

A full-scale crash test of a large troop/cargo carrying CH-47C helicopter was conducted at the Langley impact dynamics research facility. The crash test of this large helicopter was performed as part of a joint U.S. Army-NASA helicopter test program to provide dynamic structural and seat response data. The test, the procedures employed, the instrumentation, a general assessment of the resulting damage, and typical levels of accelerations experienced during the crash are reported. Various energy-absorbing seating systems for crew and troops were installed and instrumented to provide data for use in the development of design criteria for future aircraft. The crash conditions were selected to simulate known crash conditions and are representative of the 95th percentile accident environment for an autorotating helicopter. Visual examination of the crashed test specimen indicated irreparable damage to many of the structural components. The highest accelerations were recorded by the accelerometers located on the cabin floor in the aft section of the helicopter, directly above the primary impact location and on the floor of the cockpit above the secondary impact location(s).

Castle, C. B.↗
NASA NTRS1977

Aerodynamic heating in large cavities in an array of RSI tiles

A large panel of reusable surface insulation (RSI) tiles including lost tile cavities was aerothermally tested in the Langley 8 foot high temperature structures tunnel to determine both the heat load within the cavities and the structural performance of the RSI surrounding the cavities. Tests were conducted with a turbulent boundary layer at a nominal free stream Mach number of 6.6, a total temperature of 1800 K, a Reynolds number per meter of 5 million, and a dynamic pressure of 62 kPa. The maximum aerodynamic heating to the floor of the cavity was two to three times the normal surface heating. The cavity heating rates agreed with data from other facilities and were successfully correlated with an empirical equation. A zippering failure occurred to a tile downstream of a double tile cavity when the separated flow attached to the floor of the cavity and forced the tile from its position.

Hunt, L. R.↗
NASA NTRS1976

Geologic structure of the eastern mare basins

The thickness of mare basalts in the eastern maria are estimated and isopachs of the basalts are constructed. Sub-basalt basin floor topography is determined, and correlations of topographic variations of the surface with variations in basalt thickness or basin floor topography are investigated.

Dehon, R. A.↗
NASA NTRS1978

Noise-Induced Building Vibrations Caused by Concorde and Conventional Aircraft Operations at Dulles and Kennedy International Airports

Outdoor and indoor noise levels resulting from aircraft flyovers and certain nonaircraft events were recorded, as were the associated vibration levels in the walls, windows, and floors at building test sites. In addition, limited subjective tests were conducted to examine the human detection and annoyance thresholds for building vibration and rattle caused by aircraft noise. Representative peak levels of aircraft noise-induced building vibrations are reported and comparisons are made with structural damage criteria and with vibration levels induced by common domestic events. In addition, results of a pilot study are reported which indicate the human detection threshold for noise-induced floor vibrations.

Mayes, W. H.↗
NASA NTRS1977

Endogenic modification of impact craters on Mercury

The presence of internally modified impact craters on Mercury's surface may be used to evaluate the possibility of Mercurian volcanism. Such craters are similar to the floor-fractured and mare-filled craters observed on the moon. Mariner-10 images show that most such craters occur, as on the moon, near plains-filled basins. Color-ratio images have indicated that some Mercurian craters manifest red plains materials on their floors. These features may be associated with lava analogous to mare basalts in some lunar craters, or with compositionally distinct subsurface material preserved within the impact crater. Several basins manifest photometric contrasts between basin exteriors and basin-filling plains. Dark haloes are observed around some impact craters superimposed on the interior plains. This suggests the excavation of compositionally distinct material. Some possible endogenic features are discerned, despite the poor surface resolution, such as irregular rimless depressions. It is felt that volcanism may have occurred on Mercury, and that in some areas it may be similar to that of the lunar Mare Australe region.

Schultz, P. H.↗
NASA NTRS1978

Low-speed test limit of V/STOL model located vertically off-center

A vertically off-centered V/STOL model - a 2-ft-diam three-bladed aluminum propeller operating in a rotor mode - is tested in an 8 by 12 ft wind tunnel with and without ground plane along with an associated 3 by 4.5 ft test section insert. The objective was to assess the effect of the vertically off-centered model on the low-speed test limit. The aerodynamic data of the model at a constant negative angle of attack (-3 deg) are recorded at selected tunnel dynamic pressures to provide adequate data points to define the model lift variation with respect to the tip speed ratio. The adverse effect of the rotor low-speed test limit is observed in the form of lift change with respect to the tip speed ratio. A major conclusion is that for rotors tested with a ground plane or in the vicinity of the floor, the ratio of distance between floor and model to rotor radius defines the low-speed test limits.

Shindo, S.↗
NASA NTRS1977

Aerospace technology can be applied to exploration 'back on earth'

Applications of aerospace technology to petroleum exploration are described. Attention is given to seismic reflection techniques, sea-floor mapping, remote geochemical sensing, improved drilling methods and down-hole acoustic concepts, such as down-hole seismic tomography. The seismic reflection techniques include monitoring of swept-frequency explosive or solid-propellant seismic sources, as well as aerial seismic surveys. Telemetry and processing of seismic data may also be performed through use of aerospace technology. Sea-floor sonor imaging and a computer-aided system of geologic analogies for petroleum exploration are also considered.

Jaffe, L. D.↗
NASA NTRS1978

Martian intrusions - Possible sites and implications

Both the Moon and Mars exhibit volcanic modification of impact craters characterized by subfloor intrusions that either lift the old crater floor or result in extrusions of lava. Endogenic modification of martian craters, however, probably has involved interactions between such intrusive bodies and permafrost, as suggested by differences between lunar and martian floor-fractured craters. Such interactions raise the interesting possibility for hydrothermally concentrating ores in a manner analogous to the Sudbury structure on the Earth that may be consistent with interpretations of Viking lander results.

Schultz, P. H.↗
NASA NTRS1977

On the constancy of the lunar cratering flux over the past 3.3 billion yr

Utilizing a method that minimizes random fluctuations in sampling crater populations, it can be shown that the ejecta deposit of Tycho, the floor of Copernicus, and the region surrounding the Apollo 12 landing site have incremental crater size-frequency distributions that can be expressed as log-log linear functions over the diameter range from 0.1 to 1 km. Slopes are indistinguishable for the three populations, probably indicating that the surfaces are dominated by primary craters. Treating the crater populations of Tycho, the floor of Copernicus, and Apollo 12 as primary crater populations contaminated, but not overwhelmed, with secondaries, allows an attempt at calibration of the post-heavy bombardment cratering flux. Using the age of Tycho as 109 m.y., Copernicus as 800 m.y., and Apollo 12 as 3.26 billion yr, there is no basis for assuming that the flux has changed over the past 3.3 billion yr. This result can be used for dating intermediate aged surfaces by crater density.

Guinness, E. A.↗
NASA NTRS1977

Large-scale impact and explosion craters - Comparisons of morphological and structural analogs

Crater studies indicate now that there are a broad set of morphological and structural analogs which occur in both impact and explosion craters. A description is presented of impact and explosion analogs for three basic crater types, including bowl-shaped craters, flat-floored craters with central uplift, and flat-floored craters with multirings. A systematic documentation is provided of the more critical morphological and structural analogs common between large natural bowl-shaped impact and explosion craters, between central uplift impact and explosion craters, and between multiring impact and explosion craters. The data presented consist of a set of published and unpublished cratering studies assembled into a single ordered outline with each crater described in the same format and graphic style.

Roddy, D. J.↗
NASA NTRS1977

Size-dependence in the shape of fresh impact craters on the moon

The transition from small simple craters to large complex or modified craters is characterized by eleven changes in the shape of fresh lunar craters which occur within a diameter range of 10 to 30 km. In the present paper, seven ratio-level variations - those of rim-crest diameter with depth, rim height, flank width, rimwall slope, floor diameter, circularity, and rim-crest evenness - are defined for fresh-appearing craters from the new Apollo data and are expressed mathematically where practicable. These relations constitute a shape model for interpreting fresh craters on the moon. The size dependent changes reflect the occurrence of central peaks, rimwall terraces, and a flat floor within craters measuring 10 to 20 km in diameter.

Pike, R. J.↗
NASA NTRS1979

Structural deformation at the Flynn Creek impact crater, Tennessee - A preliminary report on deep drilling

The geologic and core drilling studies described in the present paper show that the Flynn Creek crater has such distinctive morphological features as a broad flat hummocky floor; large central peak; locally terraced crater walls; uplifted, as well as flat-lying rim segments; and a surrounding ejecta blanket. The major structural features include a shallow depth of total brecciation and excavation as compared with apparent crater diameter; a thin breccia lens underlain by a thin zone of disrupted strata; concentric ring fault zones in inner rim, beneath crater wall, and outer crater floor regions; a large central uplift underlain by a narrow dipping zone of deeply disrupted strata; faulted, folded, brecciated, and fractured rim strata; and uplifted rim strata, which dip away from the crater, and flat-lying rim strata, which terminate as inward dipping rocks.

Roddy, D. J.↗
NASA NTRS1979

Moderate resolution thermal mapping of Mars - The channel terrain around the Chryse basin

Moderate resolution (about 30 km) thermal inertia estimates have been made for several regions in the northern hemisphere of Mars. Examples of these maps are presented for the region 0-45 deg N, 0-90 deg W. In the region adjoining the Chryse basin there are two major channels, Kasei Vallis and Ares Vallis, whose floor materials have higher thermal inertia than the surrounding upland regions. Moreover, there are numerous craters in the region which have high inertia-low albedo features on the crater floor.

Christensen, P. R.↗
NASA NTRS1980

A compensation mechanism for central Pacific

Geos 3 derived geoid heights and sea floor topography were averaged into 256 square areas (203 km on a side) for a region in the central Pacific containing a large portion of the Hawaiian Island chain. The whole region is about 500 m shallower than normal sea floor of the same age. The major portion of the depth anomaly is the Hawaiian swell. Data were analyzed using a two-dimensional fast Fourier transform. A transfer function was computed to determine the part of the observed geoid height that is coherent and in phase with the topography. Two models were introduced, one compensating short-wavelength topography at a shallow depth (14 km) and the other compensating the longer wavelengths by a deep mechanism. Using the transition wavelength between the two models (1100 km), an estimate is made of the amplitude and shape of the heat anomaly needed to uplift the Hawaiian swell. The peak of the anomaly has an amplitude of 530 mW/sq m and is located 275 km east of Hawaii.

Sandwell, D. T.↗
NASA NTRS1980

Infrared and radar signatures of lunar craters - Implications about crater evolution

Geological models accounting for the strongly crater size-dependent IR and radar signatures of lunar crater floors are examined. The simplest model involves the formation and subsequent 'gardening' of an impact melt layer on the crater floor, but while adequate in accounting for the gradual fading of IR temperatures and echo strengths in craters larger than 30 km in diameter, it is inadequate for smaller ones. It is concluded that quantitative models of the evolution of rock populations in regoliths and of the interaction of microwaves with regoliths are needed in order to understand crater evolutionary processes.

Thompson, T. W.↗
NASA NTRS1981

Aircraft subfloor response to crash loadings

Results are presented of an experimental and analytical study of the dynamic response to crash loadings of five different load-limiting subfloors for general aviation aircraft. These subfloors provide a high-strength structural floor platform to retain the seats and a crushable zone to absorb energy and limit vertical loads. Experimental static load-deflection data and dynamic deceleration response data for the five subfloors indicated that the high-strength floor platform performed well in that structural integrity and residual strength was maintained throughout the loading cycle. The data also indicated that some of the subfloor crush zones were more effective than others in providing nearly constant load for a range of displacement. The analytical data was generated by characterizing the nonlinear crush zones of the subfloor with static load-deflection data and using the DYCAST nonlinear finite element computer program. Comparisons between experimental and analytical data showed good correlation for the subfloors in which the static deformation mode closely approximated the dynamic deformation mode.

Carden, H. D.↗
NASA NTRS1983

Eliminating Wind Tunnel Flow Breakdown

Undesirable vortexes near floor in small wind tunnels suppressed by simple device that alters flow pattern there. Air is injected along floor and interacts with backflow from wind-tunnel model. Results in smoother, more correct air-flow and to more-reliable wind-tunnel data.

Hackett, J. E.↗
NASA NTRS1981

Determination of wind tunnel constraint effects by a unified pressure signature method. Part 1: Applications to winged configurations

A new, fast, non-iterative version of the "Wall Pressure Signature Method" is described and used to determine blockage and angle-of-attack wind tunnel corrections for highly-powered jet-flap models. The correction method is complemented by the application of tangential blowing at the tunnel floor to suppress flow breakdown there, using feedback from measured floor pressures. This tangential blowing technique was substantiated by subsequent flow investigations using an LV. The basic tests on an unswept, knee-blown, jet flapped wing were supplemented to include the effects of slat-removal, sweep and the addition of unflapped tips. C sub mu values were varied from 0 to 10 free-air C sub l's in excess of 18 were measured in some cases. Application of the new methods yielded corrected data which agreed with corresponding large tunnel "free air" resuls to within the limits of experimental accuracy in almost all cases. A program listing is provided, with sample cases.

Hackett, J. E.↗