Preliminary noise tradeoff study of a Mach 2.7 cruise aircraft

NASA computer codes in the areas of preliminary sizing and enroute performance, takeoff and landing performance, aircraft noise prediction, and economics were used in a preliminary noise tradeoff study for a Mach 2.7 design supersonic cruise concept. Aerodynamic configuration data were based on wind-tunnel model tests and related analyses. Aircraft structural characteristics and weight were based on advanced structural design methodologies, assuming conventional titanium technology. The most advanced noise prediction techniques available were used, and aircraft operating costs were estimated using accepted industry methods. The 4-engines cycles included in the study were based on assumed 1985 technology levels. Propulsion data was provided by aircraft manufacturers. Additional empirical data is needed to define both noise reduction features and other operating characteristics of all engine cycles under study. Data on VCE design parameters, coannular nozzle inverted flow noise reduction and advanced mechanical suppressors are urgently needed to reduce the present uncertainties in studies of this type

A methodology for selective removal of orbital debris

Earth-orbiting objects, large enough to be tracked, were surveyed for possible systematic debris removal. Based upon the statistical collision studies of others, it was determined that objects in orbits approximately 1000 km above the Earth's surface are at greatest collisional risk. Russian C-1B boosters were identified as the most important target of opportunity for debris removal. Currently, more than 100 in tact boosters are orbiting the Earth with apogees between 950 km and 1050 km. Using data provided by Energia USA, specific information on the C-1B booster, in terms of rendezvous and capture strategies, was discussed

Multiscale Mass-Spring Models of Carbon Nanotube Arrays Accounting for Mullins-like Behavior and Permanent Deformation

Based on a one-dimensional discrete system of bistable springs, a mechanical model is introduced to describe plasticity and damage in carbon nanotube (CNT) arrays. The energetics of the mechanical system are investigated analytically, the stress-strain law is derived, and the mechanical dissipation is computed, both for the discrete case as well as for the continuum limit. An information-passing approach is developed that permits the investigation of macroscopic portions of the material. As an application, the simulation of a cyclic compression experiment on real CNT foam is performed, considering both the material response during the primary loading path from the virgin state and the damaged response after preconditioning

Detection of Radial Bolt-Hole Cracks Using Sampled CW Ultrasonic Doppler-Shift Techniques

Recently there has been considerable interest in detecting radial cracks under fasteners in the wings of C-5A aircraft. Generally, detection is accomplished using the pulse-echo method, reflections from cracks being detected in real time. In the present study, cracks are detected by observing the ·Doppler-shifted frequency. A sample having a radial crack is mounted on a rotating platform in a water bath. A focused transducer transmits a tone burst such that only the shear mode propagates tangential to the hole in the metal. This transducer receives a Doppler-shifted reflected signal whenever a moving crack is in the field of view of the incident beam. The received signal is heterodyned, filtered, and displayed on a low-frequency spectrum analyzer. Merits and limitations of the technique are discussed

A space station Structures and Assembly Verification Experiment, SAVE

The Space Station structure has been baselined to be a 5 M (16.4 ft) erectable truss. This structure will provide the overall framework to attach laboratory modules and other systems, subsystems and utilities. The assembly of this structure represents a formidable EVA challenge. To validate this capability the Space Station Structures/Dynamics Technical Integration Panel (TIP) met to develop the necessary data for an integrated STS structures flight experiment. As a result of this meeting, the Langley Research Center initiated a joint Langley/Boeing Aerospace Company study which supported the structures/dynamics TIP in developing the preliminary definition and design of a 5 M erectable space station truss and the resources required for a proposed flight experiment. The purpose of the study was to: (1) devise methods of truss assembly by astronauts; (2) define a specific test matrix for dynamic characterization; (3) identify instrumentation and data system requirements; (4) determine the power, propulsion and control requirements for the truss on-orbit for 3 years; (5) study the packaging of the experiment in the orbiter cargo bay; (6) prepare a preliminary cost estimate and schedule for the experiment; and (7) provide a list of potential follow-on experiments using the structure as a free flyer. The results of this three month study are presented

Consolidation of Geologic Studies of Geopressured-Geothermal Resources in Texas

In a five-county area of South Texas, geopressured-geothermal reservoirs in the upper Wilcox Group are colocated with heavy-oil reservoirs in the overlying Jackson Group. In 1990, research at the Bureau of Economic Geology concentrated on evaluating the potential of using geopressured-geothermal water for hot-water flooding of heavy-oil reservoirs. Favorable geothermal reservoirs are defined by thick deltaic sandstones and growth-fault-bounded compartments. Potential geothermal reservoirs are present at a depth of 11,000 ft (3,350 m) to 15,000 ft (4,570 m) and contain water at temperatures of 350°F (177°C) to 383°F (195°C) in Fandango field, Zapata County. One potential geothermal reservoir sandstone in the upper Wilcox (R sandstone) is composed of a continuous sand body 100 ft (30 m) to greater than 200 ft (>61 m) thick. Fault blocks average 2 to 4 mi^2 (5.2 to 10.4 km^2) in area. Both heavy-oil (average API=19) and light-oil (average API=26) reservoirs in South Texas are present in sandstones of the Jackson Group Mirando trend. The updip pinch-out of strike-oriented sheet sandstones in the Jackson Group largely controls the distribution of Mirando-trend heavy-oil reservoirs. The lateral continuity of heavy-oil reservoirs minimizes reservoir compartmentalization, which could disrupt injected-fluid flow paths. Geologic and engineering research that still needs to be conducted includes (1) studies of the chemical compatibility between injected geothermal fluids and clay matrix of heavy-oil reservoirs, (2) detailed field studies of geometry and size of geothermal reservoirs, (3) detailed field studies of geometry and size of heavy-oil reservoirs, and (4) studies of changes in the temperature and chemistry of geothermal fluids when injected into heavy-oil reservoirs.Bureau of Economic Geolog

Continuum limits of bistable spring models of carbon nanotube arrays accounting for material damage

Using chains of bistable springs, a model is derived to investigate the plastic behavior of carbon nanotube arrays with damage. We study the preconditioning effect due to the loading history by computing analytically the stress-strain pattern corresponding to a fatigue-type damage of the structure. We identify the convergence of the discrete response to the limiting case of infinitely many springs, both analytically in the framework of Gamma-convergence, as well as numerically.Comment: 11 pages, 1 figur

Mineral Resource Assessment. Big Bend RanchState Natural Area, Presidio and Brewster Counties, Texas - Final Report

The Big Bend Ranch State Natural Area has a diverse geology reflecting nearly 600 million years of geologic evolution. Major geologic events include (1) deposition of elastic sedimentary rocks during the Paleozoic and their deformation (folding and faulting) at the end of the Paleozoic; (2) deposition of limestone and elastic rocks during the Cretaceous and their deformation during the early Tertiary; (3) intense extrusive and intrusive igneous activity during the middle Tertiary; and (4) major normal faulting during the late Tertiary. Almost all mineral potential of the area is associated with mid-Tertiary igneous activity. The only significant mineral production within the Ranch area was from the Fresno Mine in the western part of the Terlingua mercury district, one of the largest mining districts in Texas. This mine produced approximately 3500 flasks of mercury, mostly during World War II. Other production was minor and included some additional mercury from localities near the Fresno Mine, as well as silver-lead ore containing minor gold from a small mine in the Solitario.Bureau of Economic Geolog