Preparing oxidizer coated metal fuel particles

A solid propellant composition of improved efficiency is described which includes an oxidizer containing ammonium perchlorate, and a powered metal fuel, preferably aluminum or beryllium, in the form of a composite. The metal fuel is contained in the crystalline lattice framework of the oxidizer, as well as within the oxidizer particles, and is disposed in the interstices between the oxidizer particles of the composition. The propellant composition is produced by a process comprising the crystallization of ammonium perchlorate in water, in the presence of finely divided aluminum or beryllium. A suitable binder is incorporated in the propellant composition to bind the individual particles of metal with the particles of oxidizer containing occluded metal

Solid propulsion advanced concepts

The feasibility and application of a solid propulsion powered spacecraft concept to implement high energy missions independent of multiplanetary swingby opportunities are assessed and recommendations offered for future work. An upper stage, solid propulsion launch vehicle augmentation system was selected as the baseline configuration in view of the established program goals of low cost and high reliability. Spacecraft and propulsion system data that characterize mission performance capabilities were generated to serve as the basis for subsequent tradeoff studies. A cost effectiveness model was used for the preliminary feasibility assessment to provide a meaningful comparative effectiveness measure of the various candidate designs. The results substantiated the feasibility of the powered spacecraft concept when used in conjunction with several intermediate-sized launch vehicles as well as the existence of energy margins by which to exploit the attainment of extended mission capabilities. Additionally, in growth option applications, the employment of advanced propulsion systems and alternate spacecraft approaches appear promising

Solid propellant motor

A case bonded end burning solid propellant rocket motor is described. A propellant with sufficiently low modulus to avoid chamber buckling on cooling from cure and sufficiently high elongation to sustain the stresses induced without cracking is used. The propellant is zone cured within the motor case at high pressures equal to or approaching the pressure at which the motor will operate during combustion. A solid propellant motor with a burning time long enough that its spacecraft would be limited to a maximum acceleration of less than 1 g is provided by one version of the case bonded end burning solid propellant motor of the invention

Finite Amplitude Method for Charge-Changing Transitions in Axially-Deformed Nuclei

We describe and apply a version of the finite amplitude method for obtaining the charge-changing nuclear response in the quasiparticle random phase approximation. The method is suitable for calculating strength functions and beta-decay rates, both allowed and forbidden, in axially-deformed open-shell nuclei. We demonstrate the speed and versatility of the code through a preliminary examination of the effects of tensor terms in Skyrme functionals on beta decay in a set of spherical and deformed open-shell nuclei. Like the isoscalar pairing interaction, the tensor terms systematically increase allowed beta-decay rates. This finding generalizes previous work in semimagic nuclei and points to the need for a comprehensive study of time-odd terms in nuclear density functionals.Comment: 11 pages, 8 figures, submitted to Physical Review

Solid propellant rocket motor

The characteristics of a solid propellant rocket engine with a controlled rate of thrust buildup to a desired thrust level are discussed. The engine uses a regressive burning controlled flow solid propellant igniter and a progressive burning main solid propellant charge. The igniter is capable of operating in a vacuum and sustains the burning of the propellant below its normal combustion limit until the burning propellant surface and combustion chamber pressure have increased sufficiently to provide a stable chamber pressure

A Study of Chipped Stone Artifacts from the Redwine Site (41SM193), Smith County, Texas

This article presents a detailed analysis of chipped stone artifacts from the Redwine Site (41SM193), a Middle Caddo mound and village site located on the headwaters of Auburn Creek, a tributary of the Sabine River. The collection includes chipped stone recovered from the surface, test excavations, and arrow points associated with two adult burials. The site was investigated by avocational archeologist Sam Whiteside in the 1960s and more recently by Mark Walters and Patti Haskins under the direction of John Keller of Southern Archaeological Consultants. The investigations and material culture have been briefly described. This study is designed to take a closer look at the lithics with an emphasis on technological, material, contextual, and typological analyses of the lithic artifacts, and to compare the findings to the lithics at the nearby and possibly contemporaneous Leaning Rock site (41SM325). Archaeologists generally have not focused on Caddo lithic technology, and this class of material culture remains only cursorily studied. Rather, ceramics have received the vast amount of attention with little emphasis on other types of material culture. One reason for a lack of attention to lithics may be that East Texas generally lacks the resources from which well-crafted artifacts could have been made. Small chert cobbles or pebbles, and pebbles of orthoquartzite and silicified wood constitute the major sources for chipped stone. Lacking are outcrops of excellent chert (such as the Edwards Plateau) or novaculite (eastern Oklahoma and southwestern Arkansas). Artifacts of from these two sources are introduced into East Texas in finished form. Edwards chert and novaculite debitage found in East Texas sites is likely from recycling broken finished artifacts. When lithics are reported, they are generally relegated to brief descriptive treatments with an emphasis on artifact classification and raw material distribution. Detailed technological treatments are rare (for exceptions. It is preferable in archaeological studies to integrate all classes of material culture in analysis and interpretation to see what sets of material co-occur both functionally, technologically, stylistically, and symbolically. Rarely is this extended effort even attempted in archaeological studies in Texas, but until all surviving aspects of material culture are integrated and interpreted as a cultural whole and within the known context of Caddo culture and life way, only fragments of past cultures will be stressed with the risk of gross misinterpretation. While it is acknowledged that this study treats only a fragment of the material culture from the Redwine site, I will attempt to integrate the findings in such a way as to relate it to extant information from the site available to me from other sources. Another objective of this study is to examine the lithics from the Redwine site and compare them with the sample from the nearby Leaning Rock site. Both collections are assumed to be approximately the same age and may be from the same extended Middle Caddo community. I will specifically emphasize the technological styles of the formal tools and the implications of the debitage with regards to technology and raw material

Leaning Rock Site (41SM325) Lithics

The intent of the lithic analysis from the Leaning Rock site (41SM325) in Smith County, Texas, is to glean all possible information from the artifacts. Lithic studies have taken the back seat in materials analysis from sites and projects in East Texas where archaeologists focus primarily, if not exclusively, on formal tool analysis, if any analysis is done at all. Stone tools often had complex histories, and reading these histories can provide some useful, if not the only source for, insights into tool technologies, function, style, and social inferences. Stone tools were used in entirely different functional contexts than were ceramics, and provide complimentary and often unique information not provided by any other material artifact class. The lithic analysis was conducted first to provide a descriptive report of the sample, and second to assess stylistic, chronological, functional, and behavioral information where possible. Smith County is an impoverished region in terms of lithic natural resources (Banks 1990). The materials available to the prehistoric Woodland and Caddo populations consisted mainly of orthoquartzite pebbles from extensively reworked Uvalde Pliocene gravels, small chert pebbles, silicified wood, ferruginous sandstone, and hematite. The orthoquartzite, chert, and silicified wood occur as secondary deposits in local streams. Imported chert, or rarely novaculite, can often be identified in finished artifacts such as dart points, arrow points, and finely finished biface knives. In the latter cases, the artifacts themselves were most likely introduced in finished form. Ground stone artifacts such as celts also were imported in finished form from Caddo populations that had access to the lithic resources found in the Ouachita Mountains of eastern Oklahoma and southwestern Arkansas. Given the impoverished nature of the locally available lithic resources, one of the objectives of the debitage analysis was to plot the raw material types. Technological information was limited because of the very small and fragmentary nature of the flakes and other debitage. Despite this shortcoming, some interesting observations regarding technology were possible, such as the identification of punch-produced thinning flakes and bipolar technology. The latter may have been primarily associated with silicified wood and chert pieces used as wedges to split wood. More on this topic is presented below with the discussion of “battered pieces” or wedges

Visitor experiences, values and images of Whitehaven Bay - an assessment of perceived conditions

At present, recreation and tourism are major and growing uses of the Great Barrier Reef Marine Park. Visitors are attracted to the Great Barrier Reef from all over the world to experience the beautiful islands, beaches and coral reefs. The management of this region is the responsibility of the Great Barrier Reef Marine Park Authority, who are faced with the challenge of preventing unacceptable impacts of tourism while ensuring equitable resource allocations and sustained multiple use. The Authority's goals are achieved through the development of plans of management, the provision of zoning and allocation of individual permits