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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 415 records · Page 23
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

Assured crew return vehicle post landing configuration design and test

The 1991-1992 senior Mechanical and Aerospace Engineering Design class continued work on the post landing configurations for the Assured Crew Return Vehicle (ACRV) and the Emergency Egress Couch (EEC). The ACRV will be permanently docked to Space Station Freedom fulfilling NASA's commitment of Assured Crew Return Capability in the event of an accident or illness aboard Space Station Freedom. The EEC provides medical support and a transportation surface for an incapacitated crew member. The objective of the projects was to give the ACRV Project Office data to feed into their feasibility studies. Four design teams were given the task of developing models with dynamically and geometrically scaled characteristics. Groups one and two combined efforts to design a one-fifth scale model for the Apollo Command Module derivative, an on-board flotation system, and a lift attachment point system. This model was designed to test the feasibility of a rigid flotation and stabilization system and to determine the dynamics associated with lifting the vehicle during retrieval. However, due to priorities, it was not built. Group three designed a one-fifth scale model of the Johnson Space Center (JSC) benchmark configuration, the Station Crew Return Alternative Module (SCRAM) with a lift attachment point system. This model helped to determine the flotation and lifting characteristics of the SCRAM configuration. Group four designed a full scale EEC with changeable geometric and geometric and dynamic characteristics. This model provided data on the geometric characteristics of the EEC and on the placement of the CG and moment of inertia. It also gave the helicopter rescue personnel direct input to the feasibility study. Section 1 describes in detail the design of a one-fifth scale model of the Apollo Command Module Derivative (ACMD) ACRV. The objective of the ACMD Configuration Model Team was to use geometric and dynamic constraints to design a one-fifth scale working model of the Apollo Command Module Derivative (ACMD) configuration with a Lift Attachment Point (LAP) System. This model was required to incorporate a rigidly mounted flotation system and the egress system designed the previous academic year. The LAP system was to be used to determine the dynamic effects of locating the lifting points at different locations on the vehicle. The team was then to build and test the model; however, due to priorities, this did not occur. To better simulate the ACMD after a water landing, the nose cone section was removed and the deck area exposed. The areas researched during the design process were construction, center of gravity and moment of inertia, and lift attachment points.

Source record↗
NASA NTRS1992

Post flight operation of a high peak power neodymium YAG laser aboard the G-449 payload flown on Space Shuttle Columbia mission 61-C

The Nd Yag laser flown on board the G-449 payload completed its postflight testing successfully. There was no indication that the laser had undergone any electronic or optical component failure. A postflight video was taken immediately following the return of the payload to the laboratory. Early anticipation of vibration and temperature changes contributed to the successful operation of the laser. Photographic material resulting from post flight videotape are presented. NASA safety reviews and recommendations supplied the insights which helped contribute to the successful operation of the Nd Yag laser. The safety review data is part of the technical presentation and gives some insight into why the system survived the severe environment of temperature and vibration during the flight of Space Shuttle 61-C.

Muckerheide, M. C.↗
NASA NTRS1993

Characterizing the uncertainty in holddown post load measurements

In order to understand unexpectedly erratic load measurements in the launch-pad supports for the space shuttle, the sensitivities of the load cells in the supports were analyzed using simple probabilistic techniques. NASA engineers use the loads in the shuttle's supports to calculate critical stresses in the shuttle vehicle just before lift-off. The support loads are measured with 'load cells' which are actually structural components of the mobile launch platform which have been instrumented with strain gauges. Although these load cells adequately measure vertical loads, the horizontal load measurements have been erratic. The load measurements were simulated in this study using Monte Carlo simulation procedures. The simulation studies showed that the support loads are sensitive to small deviations in strain and calibration. In their current configuration, the load cells will not measure loads with sufficient accuracy to reliably calculate stresses in the shuttle vehicle. A simplified model of the holddown post (HDP) load measurement system was used to study the effect on load measurement accuracy for several factors, including load point deviations, gauge heights, and HDP geometry.

Richardson, J. A.↗
NASA NTRS1993

LDEF: 69 Months in Space. Part 3: Second Post-Retrieval Symposium

Papers presented at the Second Long Duration Exposure Facility (LDEF) Post-Retrieval Symposium are included. The papers represent the data analysis of the 57 experiments flown on the LDEF. The experiments include materials, coatings, thermal systems, power and propulsion, science (cosmic ray, interstellar gas, heavy ions, micrometeoroid, etc.), electronics, optics, and life science.

Levine, Arlene S.↗
NASA NTRS1993

LDEF: 69 Months in Space. Second Post-Retrieval Symposium, part 2

This document is a compilation of papers presented at the Second Long Duration Exposure Facility (LDEF) Post-Retrieval Symposium. The papers represent the data analysis of the 57 experiments flown on the LDEF. The experiments include materials, coatings, thermal systems, power and propulsion, science (cosmic ray, interstellar gas, heavy ions, micrometeoroid, etc.), electronics, optics, and life science.

Levine, Arlene S.↗
NASA NTRS1993

LDEF: 69 Months in Space. Part 1: Second Post-Retrieval Symposium

A compilation of papers presented at the Second Long Duration Exposure Facility (LDEF) Post-Retrieval Symposium is included. The papers represent the data analysis of the 57 experiments flown on the LDEF. The experiments include materials, coatings, thermal systems, power and propulsion, science (cosmic ray, interstellar gas, heavy ions, micrometeoroid, etc.), electronics, optics, and life sciences.

Levine, Arlene S.↗
NASA NTRS1993

LDEF: 69 Months in Space. Part 4: Second Post-Retrieval Symposium

A compilation of papers presented at the Second Long Duration Exposure Facility (LDEF) Post-Retrieval Symposium are presented. The papers represent the data analysis of the 57 experiments flown on the LDEF. The experiments include materials, coatings, thermal systems, power and propulsion, science (cosmic ray, interstellar gas, heavy ions, micrometeoroid, etc.), electronics, optics, and life sciences.

Levine, Arlene S.↗
NASA NTRS1993

LDEF Space Plasma-High Voltage Drainage Experiment post-flight results

The Space Plasma-High Voltage Drainage Experiment (SP-HVDE) was comprised of two identical experimental trays. With one tray located on the leading (ram facing, B10) edge and the other located on the trailing (wake facing, D4) edge of the Long Duration Exposure Facility (LDEF), it was possible to directly compare the effects of ram and wake spacecraft environments on charged dielectric materials. Six arrays of Kapton dielectric samples of 2 mil, 3 mil, and 5 mil thicknesses maintained at +/- 300, +/- 500, and +/- 1000 voltage bias formed the experimental matrix of each tray. In addition, each tray carried two solar cell strings, one biased at +300 volts and the other at -300 volts, to study current leakage from High Voltage Solar Arrays (HVSA). The SP-HVDE provides the first direct, long-term, in-flight measurements of average leakage current through dielectric materials under electric stress. The experiment also yields information on the long term stability of the bulk dielectric properties of such materials. Data and findings of the SP-HVDE are an extension of those from shorter term flight experiments such as the PIX-1 (Plasma Interaction Experiment) and PIX-2 and are therefore valuable in the design and evaluation of long-lived space systems with high voltage systems exposed to the low earth orbital environment. A summary of the SP-HVDE post flight analysis final report delivered to the LDEF Project Office under contract to the National Aeronautics and Space Administration is presented.

Yaung, J. Y.↗
NASA NTRS1992

Dynamic analysis of a pre-and-post ice impacted blade

The dynamic characteristics of an engine blade are evaluated under pre-and-post ice impact conditions using the NASA in-house computer code BLASIM. The ice impacts the leading edge of the blade causing severe local damage. The local structural response of the blade due to the ice impact is predicted via a transient response analysis by modeling only a local patch around the impact region. After ice impact, the global geometry of the blade is updated using deformations of the local patch and a free vibration analysis is performed. The effects of ice impact location, ice size and ice velocity on the blade mode shapes and natural frequencies are investigated. The results indicate that basic nature of the mode shapes remains unchanged after impact and that the maximum variation in natural frequencies occurs for the twisting mode of the blade.

Abumeri, G. H.↗
NASA NTRS1991

Comets in the post-Halley era. Vols. 1 & 2

The present volume on comets in the post-Halley era discusses observing techniques and intepretation, laboratory studies and simulations, the origin and evolution of comets, the cometary nucleus and coma, cometary dust, and plasmas and fields. Attention is given to IR techniques for comet observations, UV spectroscopy of cometary comae, radio interferometric imaging of comets, and irradiation effects on comets and cometary debris. Topics addressed include laboratory simulation of cometary structures, chemical theories on the origin of comets, biological implications of organic compounds in comets, the dynamic history of the Oort cloud, and physical aspects of the evolution of cometary debris. Also discussed are possible mechanisms of cometary outbursts, isotopic ratios in comets, the hydrogen clouds of comets, and physical and optical properties of cometary dust.

Newburn, R. L., Jr.↗
NASA NTRS1992

Post impact compressive behavior of composites

In this paper, the post impact compressive behavior of polymeric composites is studied both analytically and experimentally. In the analytical study, a closed-form solution is obtained for postbuckling of composites with a circular delamination. Using this solution, the reduced stiffness of the impact damaged region is calculated and the residual compressive strengths of quasi-isotropic laminates are predicted as a function of damage size. In the experimental study, in-plane displacements near the damaged region are determined by employing a micro moire interferometry technique. The strain concentrations as well as the compression-after-impact strength have been measured and compared with analytical predictions. Good agreement between the predicted results and experimental data was observed.

Lin, Kuen Y.↗
NASA NTRS1993

Active control of wing rock of a delta wing at post-stall using tangential leading edge blowing

Post-stall roll control utilizing tangential leading edge blowing is demonstrated in a wind tunnel on a delta wing model that exhibited wing rock. The dampening effect of symmetric blowing alone on wing rock is found to be effective up to a certain maximum amount of blowing. A moderate amount of symmetric blowing was shown to be effective in linearizing the asymmetric blowing static rolling moment responses.

Wong, G. S.↗
NASA NTRS1993

Spectropolarimetry of the post-main-sequence bipolar nebulae GL 618, M2-56, and M1-92

New high-quality spectropolarimetry of the post-main-sequence bipolar nebulae GL 618, M2-56, and M1-92 is presented which permits accurate separation of the scattered and unscattered components. Shock emission dominates the optical line spectrum of the three nebulae and probably plays a significant role in their dynamical evolution. The central H II region spectrum for GL 6189 is isolated and T(stellar) of 36,000-40,000 and log (N/O) = 0.0 +/- 0.2 are derived. GL 618 and M2-56 have shock velocities of 40-60 km/s; that of M1-92 is 60-100 km/s. Log (N/O) is derived for different regions of the three nebulae. There is an apparent correlation of outflow velocity with chemical abundance.

Trammell, Susan R.↗
NASA NTRS1993

The computation of the post-stall behavior of a circulation controlled airfoil

The physics of the circulation controlled airfoil is complex and poorly understood, particularly with regards to jet stall, which is the eventual breakdown of lift augmentation by the jet at some sufficiently high blowing rate. The present paper describes the numerical simulation of stalled and unstalled flows over a two-dimensional circulation controlled airfoil using a fully implicit Navier-Stokes code, and the comparison with experimental results. Mach numbers of 0.3 and 0.5 and jet total to freestream pressure ratios of 1.4 and 1.8 are investigated. The Baldwin-Lomax and k-epsilon turbulence models are used, each modified to include the effect of strong streamline curvature. The numerical solutions of the post-stall circulation controlled airfoil show a highly regular unsteady periodic flowfield. This is the result of an alternation between adverse pressure gradient and shock induced separation of the boundary layer on the airfoil trailing edge.

Linton, Samuel W.↗
NASA NTRS1993

Dynamics of the atmospheres of the outer planets - Post-Voyager measurement objectives

Current knowledge about dynamics and thermal structure on the outer planets is reviewed with the aim of identifying important measurements which should be made in the post-Voyager era. The existence of jets and cloud bands is the puzzle that underlies all others. Discussion focuses on the particular case of Jupiter because documentation is most complete. Recent dynamical work has successfully reproduced much of the behavior of jets and spots with simple models that contain few parameters. It is argued that the gross dynamical parameters, such as density stratification and rotation rate, are the keys to their behaviors, rather than the particular specifics of radiative forcing, cloud distributions, thermodynamic transformations. Voyager data have shown that the jet systems decay with height in the region above the visible clouds. Therefore the highest priority must be given to establishing dynamical parameters that characterize levels within and beneath the clouds. These require determination of the deep structure of the jets, of the density stratification, and of the horizontal density contrasts. The deep regions are not easily accessible, and these measurements present challenging opportunities. Indirect inferences about the controlling processes may sometimes be possible by observing waves and other activity in the more easily accessible stratosphere, and some of these issues are also discussed.

Gierasch, Peter J.↗
NASA NTRS1993

He 3-519 - A peculiar post-LBV, pre-WN star?

We report IUE and ground-based data indicating that the star He 3-519 has a distance of roughly 8 kpc and an absolute bolometric magnitude of about -11, comparable to AG Car. Its luminosity, spectrum, and large, massive circumstellar shell indicate that this may be a post-LBV object which has not yet become a full-fledged WN star. One notable peculiarity of He 3-519 is its prominent Fe III (?) 3008 A emission; the reason why this feature is so bright in this star's dense envelope or wind, but not in other related stars, is not yet clear.

Davidson, Kris↗
NASA NTRS1992

The origin of the extremely metal-poor post-AGB stars

Certain A-F supergiants show almost solar photospheric abundances of C, N, O, S, and Zn, while Fe, Mg, Ca, Si, Cr, and other elements are more than two orders of magnitude below solar. We suggest that the present photosphere was originally solar in composition; the missing elements were incorporated into dust grains that were separated from the atmosphere. The heavy-element-depleted gas comprises the present photosphere. There are two possible mechanisms by which this process might take place: capture by the presently visible star of the depleted gas from a binary companions, or the rapid termination of a vigorous stellar wind in a single star, so that the grains are blown outward through the expanding envelope. Besides the abundance peculiarities, the hypothesis explains why some objects have carbon-rich dust outside of an oxygen rich photosphere, why these stars have the rather narrow range of (T(eff), log g) near (7000 K, 1.0), and why some might have a great deal of circumstellar dust while others have little. Perhaps the most serious objection to the hypothesis is the possible presence of stellar winds observed in the winds of the peculiar post-AGB stars themselves.

Mathis, J. S.↗
NASA NTRS1993

Prediction of stall and post-stall behavior of airfoils at low and high Reynolds numbers

An interactive boundary-layer method, together with the e(super n)-approach to the calculation of transition, has been used to predict the stall and post-stall behavior of airfoils at low and high Reynolds numbers. The turbulence model is based on the Cebeci-Smith algebraic eddy-viscosity formulation with improvements for strong pressure gradient effects and transitional flows at low Reynolds numbers. Comparison of calculated results for incompressible flows indicate good agreement with experiment for a wide range of Reynolds numbers. Preliminary calculations for low Mach number flows with this interactive method with compressibility corrections to the panel method indicate that, at a Mach number of 0.3, the compressibility effect on (C sub Q)max is not negligible.

Cebeci, T.↗