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NASA NTRS1989

Three-dimensional analysis of surface crack-Hertzian stress field interaction

The results are presented of a stress intensity factor analysis of semicircular surface cracks in the inner raceway of an engine bearing. The loading consists of a moving spherical Hertzian contact load and an axial stress due to rotation and shrink fit. A 3-D linear elastic Boundary Element Method code was developed to perform the stress analysis. The element library includes linear and quadratic isoparametric surface elements. Singular quarter point elements were employed to capture the square root displacement variation and the inverse square root stress singularity along the crack front. The program also possesses the capability to separate the whole domain into two subregions. This procedure enables one to solve nonsymmetric fracture mechanics problems without having to separate the crack surfaces a priori. A wide range of configuration parameters was investigated. The ratio of crack depth to bearing thickness was varied from one-sixtieth to one-fifth for several different locations of the Hertzian load. The stress intensity factors for several crack inclinations were also investigated. The results demonstrate the efficiency and accuracy of the Boundary Element Method. Moreover, the results can provide the basis for crack growth calculations and fatigue life prediction.

Ballarini, R.↗

NASA NTRS1994

Early differentiation of the Moon: Experimental and modeling studies and experimental and modeling studies of massif anorthosites

NASA grant NAG9-329 was in effect from 3/1/89 to 8/31/94, the last 18 months being a no-cost extension. While the grant was in effect, the P.I., coworkers, and students gave 22 talks and poster sessions at professional meetings, published 12 articles in referred journals (one more is in press, and another is in review), and edited 2 workshop reports relevant to this project. Copies of all the publications are appended to this report. The major accomplishments during the grant period have derived from three quarters: 1) the application of quantitative models of fractional crystallization and partial melting to various problems in planetary science, such as the petrogenesis of picritic glasses and mare basalts and the implications of the SNC meteorites for martian evolution; 2) an experimental study of silicate liquid immiscibility relevant to early lunar differentiation and the petrogenesis of evolved highlands rocks; and 3) experimental studies of massif anorthosites and related rocks that provide terrestrial analogs for the proposed origin of lunar anorthosites by multistage processes. The low-pressure aspects of the quantitative models were developed by the P.I. in the 1980s with NASA support and culminated with a paper comparing the crystallization of terrestrial and lunar lavas. The basis for the high-pressure modifications to the quantitative models is a data set gleaned from high pressure melting experiments done at Lamont and is supplemented by published data from other labs that constrain the baric and compositional dependences of various liquidus phase boundaries such as olivine/orthopyroxene, relevant to the melting of the mantles of the terrestrial planets. With these models it is possible to predict not only the thermal and compositional evolution of magmatic liquids ranging in composition from lumar mare basalt to terrestrial calc-alkaline basalts, but also the small increments of fractional melting that are produced when mantle rises adiabatically. Copies of the crystallization/melting programs have been given to several colleagues in planetary science. Additionally, a series of computer graphics programs, based on the algorithms in the crystallization programs have been developed that display liquidus diagrams appropriate to input compositions.

Longhi, John↗

NASA NTRS1951

Investigation of the Effects of Twist and Camber on the Aerodynamic Characteristics of a 50 Degrees 38 Minutes Sweptback Wing of Aspect Ratio 2.98 : Transonic-bump Method

An investigation of two semispan wings swept back 50 degrees 38 minutes was conducted in the Langley high-speed 7- by 10-foot tunnel over a Mach number range of 0.68 to 1.15 by use of the transonic-bump technique. This paper presents the results of the investigation of wing-alone and wing-fuselage configurations of the two wings; one was an untwisted uncambered wing and the other was the same wing but incorporated twist and camber designed to give uniform load at a lift coefficient of 0.25 at a Mach number of 1.10. The semispan wings had their quarter-chord lines swept back 50 degrees 38 minutes, aspect ratios 2.98, taper ratios 0.45, and modified NACA 64A-series airfoil sections tapered in thickness. Lift, pitching moment, drag, and bending moment were obtained for these configurations.

WINGS, COMPLETE - DESIGN VARIABLES↗

NASA NTRS1988

Temperature Pill

Ingestible Thermal Monitoring System was developed at Johns Hopkins University as means of getting internal temperature readings for treatments of such emergency conditions as dangerously low (hypothermia) and dangerously high (hyperthermia) body temperatures. ITMS's accuracy is off no more than one hundredth of a degree and provides the only means of obtaining deep body temperature. System has additional applicability in fertility monitoring and some aspects of surgery, critical care obstetrics, metabolic disease treatment, gerontology (aging) and food processing research. Three-quarter inch silicone capsule contains telemetry system, micro battery, and a quartz crystal temperature sensor inserted vaginally, rectally, or swallowed.

Source record↗

NASA NTRS2001

NASA Multipoint LDI Development

Multipoint Lean-Direct-Injection (LDI) is a combustor concept in which a large number of fuel injectors and fuel-air mixers are used to quickly and uniformly mix the fuel and air so that ultralow levels of NO, are produced. Each fuel injector has an air swirler associated with it for fuel-air mixing and to establish a small recirculation and burning zone. A concept in which there are 36 fuel injectors in the space of a conventional single fuel injector has been tested in a flame tube. A greater than 80 percent reduction in NO, at high power conditions (400 psia, 1000 "Finlet) was achieved. Alternate concepts with 9,25,36 or 49 fuel injectors are being investigated in flame tube tests for their low NO, potential and with fuel staging to improve the turn-down ratio at low power conditions. A preliminary sector concept of a large engine design has been successfully tested at inlet conditions of 700 psia and 1100 O F . This concept had one half the number of fuel injectors per square inch as the flame tube configuration with 36 fuel injectors, and the NO, reduction was 65 percent of the ICAO standard. Future regional engine size sector tests are planned for the 2nd quarter of FY02 and large engine size sector tests for the 1st quarter of FY03.

Tacina, Robert↗

NASA NTRS1977

Passive thermosyphon solar heating and cooling module with supplementary heating

A collection of three quarterly reports from Sigma Research, Inc., covering progress and status from January through September 1977 are presented. Three heat exchangers are developed for use in a solar heating and cooling system for installation into single-family dwellings. Each exchanger consists of one heating and cooling module and one submerged electric water heating element.

Source record↗

NASA NTRS1961

An Investigation of Wing and Aileron Loads Due to Deflected Inboard and Outboard Ailerons on a 4-Percent-Thick 30 deg Sweptback Wing at Transonic Speeds

An investigation has been conducted in the Langley 16-foot transonic tunnel to determine the changes in wing loading characteristics due to deflections of a plain faired flap-type inboard aileron, a plain faired flap-type outboard aileron, and a slab-sided thickened trailing edge outboard aileron. The test wing was 4 percent thick and had 30 sweep of the quarter chord, an aspect ratio of 3.0, a taper ratio of 0.2, and NACA 65A004 airfoil sections. The loading characteristics of the deflected ailerons were also investigated. The model was a sting-mounted wing-body combination, and pressure measurements over one wing panel (exposed area) and the ailerons were obtained for angles of attack from 0 to 20 at deflections up to +/- 15 deg for Mach numbers between 0.80 and 1.03. The test Reynolds number based on the wing mean aerodynamic chord was about 7.4 x 10(exp 6). The results of the investigation indicated that positive deflection of the plain faired flap-type inboard aileron caused significant added loading over the wing sections outboard of the aileron at all Mach numbers for model angles of attack from 0 deg or 4 deg up to 12 deg. Positive deflection of the two outboard ailerons (plain faired and slab sided with thickened trailing edge) caused significant added loading over the wing sections inboard of the ailerons for different model angle-of-attack ranges at the several test Mach numbers. The loading shapes over the ailerons were irregular and would be difficult to predict from theoretical considerations in the transonic speed range. The longitudinal and lateral center-of-pressure locations for the ailerons varied only slightly with increasing angle of attack and/or Mach number. Generally, the negative slopes of the variations of aileron hinge-moment coefficient with aileron deflection for all three ailerons varied similarly with Mach number at the test angles of attack.

Whitcomb, Charles F.↗

NASA NTRSDate not supplied

New Hayabusa2 and OSIRIS REx Curation Facilities at Nasa Johnson Space Center

Asteroids are made up of rocky material that is left over from the formation of our solar system [1]. This material holds the key to unlocking information about the history of the planets and our sun. Hayabusa2 and OSIRIS-REx are two sample return missions that have collected rocky material from carbonaceous asteroids which are rich in water, carbon, and organic compounds [1]. Hayabusa2 is a spacecraft that collected samples from asteroid Ryugu launched by the Japan Aerospace Exploration Agency (JAXA). Samples were returned to Earth in December 2020 and 10 percent of the collected material is currently housed in a state-of-the-art laboratory at NASA Johnson Space Center (JSC) dedicated to Ryugu material [1]. OSIRIS-REx is a spacecraft launched by NASA that collected samples from asteroid Bennu. The samples are on their journey to Earth and will arrive in September 2023. They will be stored in a separate cleanroom dedicated to Bennu material. From these two missions, scientists will examine dust particles and rocky material to research clues on how the early solar system formed and how life began [2]. Because these samples are so precious and rare, it is important to keep them free from Earth contamination. In September of 2020, a massive construction project began to provide curation facilities to meet the needs of two incoming asteroid collections, Hayabusa2 and OSIRIS-REx. Despite numerous setbacks caused by the coronavirus pandemic, these facilities have been completed in the fall of 2021. Some of these setbacks included strict PPE requirements, keeping safe working distances as well as access to the facilities as NASA was operating under a Stage 3 condition in response to the pandemic. These facilities will provide curation laboratories to safely house the precious asteroid samples as well as facilities to manipulate samples, do sample preparation and process samples into and out of the labs for future studies by the scientific community. The lab suite consists of several different rooms including an initial anteroom (ISO 7), a staging area (ISO 7), two gowning areas (one for OSIRIS-REx and one for Hayabusa2; both ISO 6)), the Haybusa2 Curation Laboratory (ISO 5), the OSIRIS-REx Curation Laboratory (ISO 5), an ultramicrotomy laboratory (ISO 7) and a thin section laboratory (not a cleanroom). To maintain cleanliness levels necessary for these lab spaces quarterly to monthly Balazs organic and inorganic sampling has been conducted on a regular basis before, during and after the construction project to monitor the cleanliness levels in the new labs that will house the asteroid samples. These new facilities feature a Ruuvi (Grafana) monitoring system that measures temperature, humidity, and pressure of the lab suite. This is a small puck shaped sensor that sends signals to the Grafana cloud where the data can be plotted and set up on dashboards within the lab suite. These sensors are easy to set up and install and they run off a cell battery that is good for 3-5 years before needing replacement. This system can deliver text messages and emails to the appropriate personnel when values fall outside of set limits. In addition to the monitoring system, this new lab suite features viewing windows from several different locations and sliding motion censored doors. We have obtained some state-of-the-art equipment to outfit the lab spaces (desiccators, microscopes, ultramicrotome) and are in the process of outfitting the suite with additional items such as: nitrogen gloveboxes, additional desiccators, micromanipulators, etc. The Hayabusa2 samples provided to NASA by JAXA included 23 millimeter sized grains and 4 containers with finer material. OSIRIS-REx is expected to return as much as 400 grams of asteroid Bennu. Samples will be stored in a nitrogen glove box and separated into nitrogen sealed transfer containers. Small Bennu and Ryugu particles will be handled and prepared (e.g., ultra-thin sections for scanning electron microscopy (SEM) or transmission electron microscopy (TEM)) using an Axis Pro micromanipulator and Leica EM UC7 ultramicrotome. Analyzing samples at the atomic scale will provide greater insight to the origins of the solar system and life formation on Earth. All the curation preparation for these sample collections is essential to ongoing research and efforts to understand our solar system, both nowand for future generations.

Curation↗

NASA NTRS1993

A computer-controlled x-y offset guiding stage for the MLRS

The MLRS has experienced excellent success in its lunar and artificial satellite laser ranging operations during its many years of operation, in spite of its relatively small 'receive' aperture. We continue to strive, however, for a greater volume of data, together with better accuracy and precision. We have just now completed the design, construction, and implementation of a computer controlled x-y offset guiding stage for the MLRS, analogous to the manual one that had been a part of the original 2.7-m lunar laser ranging system on Mt. Locke at McDonald Observatory. In the past, we had been hampered by the lack of a satisfactory hardware design which could fit within the very cramped quarters of the MLRS telescope's tail piece. Recently, with funding support from the U.S. Naval Observatory and the design and construction expertise of DFM Engineering, Inc., a satisfactory instrument has been specified, designed, built, and installed. This instrument will greatly expand MLRS observational opportunities by allowing the observing crews to actively guide on visible off axis lunar surface features or background stars while the on-axis lunar surface retroreflector targets are in the dark. This paper describes this instrument and its present implementation at the MLRS.

Shelus, Peter J.↗

NASA NTRS2006

Theory of Radiation Transfer in Neutron Star Atmospheres

The possibility for direct investigation of thermal emission from isolated neutron stars opened about a quarter of century ago with the launch of the first X-ray observatories Einstein and EXOSAT stimulated developing models of the neutron star surface radiation which began at the end of 80's. Confronting observational data with theoretical models of thermal emission allows one to infer the surface temperatures, magnetic fields, chemical composition, and neutron star masses and radii. This information, supplemented with the model equations of state and neutron star cooling models, provides an opportunity to understand the fundamental properties of the superdense matter in the stars' interiors. Almost all available models are based on the assumption that thermal radiation emitted by a neutron star is formed in the superficial star's layers--atmosphere. The neutron star atmospheres are very different from those of usual stars due to the immense gravity and huge magnetic fields. In this presentation we review the current status of the neutron star atmosphere modeling, present most important results, discuss problems and possible future developments.

Zavlin, Vyacheslav↗

NASA NTRS2006

Full-Duplex Digital Communication on a Single Laser Beam

A proposed free-space optical communication system would operate in a full-duplex mode, using a single constant-power laser beam for transmission and reception of binary signals at both ends of the free-space optical path. The system was conceived for two-way data communication between a ground station and a spacecraft in a low orbit around the Earth. It has been estimated that in this application, a data rate of 10 kb/s could be achieved at a ground-station-to-spacecraft distance of 320 km, using a laser power of only 100 mW. The basic system concept is also applicable to terrestrial free-space optical communications. The system (see figure) would include a diode laser at one end of the link (originally, the ground station) and a liquid-crystal- based retroreflecting modulator at the other end of the link (originally, the spacecraft). At the laser end, the beam to be transmitted would be made to pass through a quarter-wave plate, which would convert its linear polarization to right circular polarization. For transmission of data from the laser end to the retroreflector end, the laser beam would be modulated with subcarrier phase-shift keying (SC-PSK). The transmitted beam would then pass through an aperture- sharing element (ASE) - basically, a mirror with a hole in it, used to separate the paths of the transmitted and received light beams. The transmitted beam would continue outward through a telescope (which, in the original application, would be equipped with a spacecraft-tracking system) that would launch the transmitted beam along the free-space optical path to the retroreflector end.

Hazzard, D. A.↗

NASA NTRS2019

Preface to the Special Collection: Recollections in Space Physics

Space Physics is a comparatively young scientific discipline, tightly linked to the era of satellite based investigations and the discoveries that came with it. As such, we as a community are fortunate to have met, been taught and mentored by, and even become friends with, many of those who were around to witness the birth of, and in many cases establish, our field. Each of these "Pioneers" have remarkable stories to tell. These accounts from the dawn of the space age provide a glimpse into that era of scientific discovery and are an important part of our collective history that deserve to be shared and commemorated. These are stories of perseverance, ingenuity, luck, and sometimes failure. We are fortunate to live in an era in which these distinguished scientists are still with us and able to share their experiences.To commemorate the 100th Anniversary of the American Geophysical Union (AGU), we have solicited a special collection of recollection papers to memorialize these experiences. This is not the first such effort to capture these stories. In 1994 (Vol. 99, No. A10, pp. 19,099-19,212) and again in 1996 (Vol. 101, No. A5, pp. 10,477-10,585) JGRSpace Physics published special sections entitled, "Pioneers of Space Physics," in celebration of AGU's 75th anniversary. Later, in 1997, Gilmore and Spreiter (1997) added a set of recollection papers on the discovery of the magnetosphere. Together, these papers containing personal accounts from the pioneers of the space age covered the period of roughly 1958-1967.It is our great honor to present retrospective papers from several of our distinguished colleagues who contributed significantly to the explosion in understanding of space physics and aeronomy that occurred from roughly 1967-1980. We chose to start at the end of the previous set of recollections and cover the decade of the 1970s, during which our field greatly expanded. It is also a time in which the second generation of space scientists entered the field and made foundational discoveries that continue to define our discipline.As with the previous papers, we asked the authors to "recount some of the events leading to the emergence of space physics and to put the events into a professional as well as personal perspective." (Gombosi et al.,1994). The authors of this special collection of recollections were selected following the same guidelines as the previous efforts. We started from a long list of senior colleagues and narrowed the list to roughly two dozen distinguished scientists based on discipline and geographic balance. Some of our colleagues, when asked, felt they would be unable to devote the time or energy to such a recollection and declined. Sadly,in the intervening 25 years since the original effort, some of our colleagues who were most active during the early years of the space age have passed. Therefore, this new special collection, 25 years after the first one, is timely with the AGU centennial celebrations, but late in fully capturing the stories of the pioneers of space physics. This is unfortunate and we encourage future editors of this journal to commission specialsections of legacy perspectives with a faster cadence than a quarter of a century.

Kepko, Emil L.↗

NASA NTRS1985

Measurements of vector fields with diode array

A polarimeter was designed for high spatial and spectral resolution. It consists of a quarter-wave plate alternately operating in two positions for Stoke-V measurements and an additional quarter-wave plate for Stokes-U and -Q measurements. The spatial range covers 75 arcsec, the spectral window of about 1.8 a allows the simultaneous observations of neighboring lines. The block diagram of the data processing and acquisition system consists of five memories each one having a capacity of 10 to the 4th power 16-bit words. The total time to acquire profiles of Stokes parameters can be chosen by selecting the number of successive measurements added in the memories, each individual measurement corresponding to an integration time of 0.5 sec. Typical values range between 2 and 60 sec depending on the brightness of the structure, the amount of polarization and a compromise between desired signal-to-noise ratio and spatial resolution.

Wiehr, E. J.↗

NASA NTRS2000

Solution to Darwin's dilemma: discovery of the missing Precambrian record of life

In 1859, in On the Origin of Species, Darwin broached what he regarded to be the most vexing problem facing his theory of evolution-the lack of a rich fossil record predating the rise of shelly invertebrates that marks the beginning of the Cambrian Period of geologic time ( approximately 550 million years ago), an "inexplicable" absence that could be "truly urged as a valid argument" against his all embracing synthesis. For more than 100 years, the "missing Precambrian history of life" stood out as one of the greatest unsolved mysteries in natural science. But in recent decades, understanding of life's history has changed markedly as the documented fossil record has been extended seven-fold to some 3,500 million years ago, an age more than three-quarters that of the planet itself. This long-sought solution to Darwin's dilemma was set in motion by a small vanguard of workers who blazed the trail in the 1950s and 1960s, just as their course was charted by a few pioneering pathfinders of the previous century, a history of bold pronouncements, dashed dreams, search, and final discovery.

Review↗

NASA NTRS1976

Nonlinear Equations of Motion for Cantilever Rotor Blades in Hover with Pitch Link Flexibility, Twist, Precone, Droop, Sweep, Torque Offset, and Blade Root Offset

Nonlinear equations of motion for a cantilever rotor blade are derived for the hovering flight condition. The blade is assumed to have twist, precone, droop, sweep, torque offset and blade root offset, and the elastic axis and the axes of center of mass, tension, and aerodynamic center coincident at the quarter chord. The blade is cantilevered in bending, but has a torsional root spring to simulate pitch link flexibility. Aerodynamic forces acting on the blade are derived from strip theory based on quasi-steady two-dimensional airfoil theory. The equations are hybrid, consisting of one integro-differential equation for root torsion and three integro-partial differential equations for flatwise and chordwise bending and elastic torsion. The equations are specialized for a uniform blade and reduced to nonlinear ordinary differential equations by Galerkin's method. They are linearized for small perturbation motions about the equilibrium operating condition. Modal analysis leads to formulation of a standard eigenvalue problem where the elements of the stability matrix depend on the solution of the equilibrium equations. Two different forms of the root torsion equation are derived that yield virtually identical numerical results. This provides a reasonable check for the accuracy of the equations.

Hodges, D. H.↗

NASA NTRS1978

Application of remote sensing technology to the solution of problems in the management of resources in Indiana

The author has identified the following significant results. Twenty-eight quarter sections were mapped, representing a total area of 4480 acres or approximately 1.25% of the county. Soil series were not consistently separated on a countywide basis. When internal drainage and parent materials were ascertained, a soil series could be predicted. Each soil spectral class represented one predominant drainage class with minor inclusions of other drainage classes. The same is true with conventional field mapping units that also contain minor inclusions of other drainage classes. Most wetlands could be identified in the LANDSAT classification. There appeared to be some confusion in distinguishing between different wetland types and between some wetland and upland cover types.

Weismiller, R. A.↗

NASA NTRS2003

Wilbur and Orville Wright: A Reissue of a Chronology Commemorating the Hundredth Anniversary of the Birth of Orville Wright, August 19, 1871

During the year 2003, hundreds of events will mark the one-hundredth anniversary of the Wright brothers historic first flights at Kitty Hawk, North Carolina. The centennial year will witness exhibitions, lectures, television documentaries, films, air shows, flight recreations of Wright aircraft, the issuing of postage stamps and medals, the publication of dozens of new books and articles, and numerous other commemorative activities. One of these events, although not likely to make the evening news, is among the most important of all in terms of a lasting contribution to the observance of this ultimate aviation milestone: the reprinting of Arthur G. Renstrom WIlbur & Orville Wrght: A Chronology Commemorating the Hundredth Anniversary of the Birth of Orville Wright, August 19, 1871. Since its appearance in 1975, Wilbur end Orville Wright: A Chronology has become indispensable to students and authors concerned with the life and work of the famous brothers. No doubt every book on the subject published in the last quarter century, including three of my own, was written with this treasure close at hand. This volume is far more than a simple compilation of dates and facts. Renstrom was a master reference librarian and bibliographer with a passion for aviation and the Wright brothers. He brought his considerable research skills to bear on the topic, and the result is a richly detailed, ever-informative, often entertaining walk through the lives and achievements of these two extraordinary individuals. Renstrom was not content to offer a date with a one-line tidbit. His entries are brimming with information. This is a highly readable reference work that, believe it or not, can be enjoyably read from cover to cover. The project was clearly a labor of love by a talented professional. During most of the last twenty years, I have been privileged to be the curator of the 1903 Wright Flyer at the Smithsonian Institution s National Air and Space Museum. The position brings a steady stream of inquiries about the Wright airplane and the endlessly fascinating brothers who created it. I do not know how I would have done this job without Renstrom s superb volume on my bookshelf. It is the first place I go to check anything on the Wright brothers, and I typically find what I am looking for in its pages. Arthur Renstrom also published two other classic reference works on the Wright brothers: Wilbur & Orville Wright: A Bibliography Commemorating the Hundredth Anniversary of the Birth of Wilbur Wright, April 16, 1867, in 1968 (an updated revision was published by the National Aeronautics and Space Administration in 2002) and Wilbur & Orville Wright, Pictorial Materials: A Documentary Guide in 1982, completing a series of research tools for which there are few peers on any subject. He was also part of the team that produced the landmark two-volume compilation of the Wrights letters, notebooks, and diaries in 1953, The Papers of Wilbur and Orville Wright, edited by Marvin W. McFarland. Renstrom s contribution to the documentation and preservation of the Wright story is a lasting legacy that will serve researchers, students, and general enthusiasts for generations to come. In this busy, high-profile anniversary year, the reprinting of a nearly thirty-year-old reference book may seem a mundane and quiet contribution to the celebration surrounding the Wright brothers world-changing achievement, but it is perhaps one of the most important. The U.S. Centennial of Flight Commission and NASA are to be commended for their foresight.

Renstrom, Arthur George↗

NASA NTRS1983

Aerodynamic theory for wing with side edge passing subsonically through a gust

An approximate solution for the unsteady loading near the square-shape tip of a wing passing through an oblique gust is obtained in closed form. The aerodynamic theory developed can be used to predict airloads felt by a helicopter blade experiencing a blade/vortex interaction for high blade tip speed and/or for small vertical blade/vortex separation. Under these conditions one can show that the blade's trailing edge has little influence on the character of the chordwise loading at all spanwise sections; thus, the chord may be allowed to extend to infinity in the downstream direction. Therefore, the model considered here is that of a quarter-infinite flat plate wing with side edge passing subsonically through an oblique gust.

Martinez, R.↗