Scale Effects on Quasi-Steady Solid Rocket Internal Ballistic Behaviour

The ability to predict with some accuracy a given solid rocket motor’s performance before undertaking one or several costly experimental test firings is important. On the numerical prediction side, as various component models evolve, their incorporation into an overall internal ballistics simulation program allows for new motor firing simulations to take place, which in turn allows for updated comparisons to experimental firing data. In the present investigation, utilizing an updated simulation program, the focus is on quasi-steady performance analysis and scale effects (influence of motor size). The predicted effects of negative/positive erosive burning and propellant/casing deflection, as tied to motor size, on a reference cylindrical-grain motor’s internal ballistics, are included in this evaluation. Propellant deflection has only a minor influence on the reference motor’s internal ballistics, regardless of motor size. Erosive burning, on the other hand, is distinctly affected by motor scale.

Scale Effects on Quasi-Steady Solid Rocket Internal Ballistic Behaviour

The ability to predict with some accuracy a given solid rocket motor’s performance before undertaking one or several costly experimental test firings is important. On the numerical prediction side, as various component models evolve, their incorporation into an overall internal ballistics simulation program allows for new motor firing simulations to take place, which in turn allows for updated comparisons to experimental firing data. In the present investigation, utilizing an updated simulation program, the focus is on quasi-steady performance analysis and scale effects (influence of motor size). The predicted effects of negative/positive erosive burning and propellant/casing deflection, as tied to motor size, on a reference cylindrical-grain motor’s internal ballistics, are included in this evaluation. Propellant deflection has only a minor influence on the reference motor’s internal ballistics, regardless of motor size. Erosive burning, on the other hand, is distinctly affected by motor scale.

Influence of firing conditions on the rock magnetic properties. Preliminary results from experimental heating experiments

<p>Archaeomagnetism deals with baked clay materials carrying a thermoremanent magnetization acquired in the Earth`s magnetic field, which determines its importance for two scientific fields – geophysics and archaeology. It is well known that the success of an archaeomagnetic study is closely related to the magnetic properties of the materials used. In turn, the magnetic properties depend on the initial clay mineralogy, firing conditions and burial history. In order to get more information about the influence of the firing process, samples prepared of raw clays (taken from six different sources) were subjected to the successive experimental baking in three experimental combustion structures: open-hearth, single-chamber round furnace and double-chamber rectangular kiln. Heating and cooling temperatures in the various parts of the structures were constantly monitored. Rock magnetic measurements and analyses were carried out prior to, after the first and after the fourth experimental firing.</p><p>The heating/cooling cycle in the single-chamber furnace was the most prolonged. The temperatures achieved vary from 400 to 540°C displaying very uneven distribution after 400 °C. Maximum temperatures of about 850 – 900°C were reached in the hearth and in the double-chamber kiln but they were retained for a relatively short time (5 – 10 min) whether or not extra fuel was added. The heating and especially the cooling were the most homogeneous in the double-chamber kiln, where the cooling temperatures in its different parts varied within 50°C. In contrast, these temperatures differ by about 250°C in the single-chamber furnace and almost 400°C in the hearth.</p><p>X-ray diffraction analyses classify the chosen six clays as calcareous (all grayish clays) and non-calcareous (all brownish clays).  Magnetic susceptibility behaviour monitored during stepwise heating and the shape of alternative field demagnetization curves of laboratory induced isothermal magnetization divided clays into three groups. Remanence and magnetic susceptibility measured after the first experimental firing are quite variable according to the clay type, structure and samples position, but some trends are obvious. The lowest magnetic properties generally correspond to the samples heated in the single-chamber furnace where the lowest firing temperatures developed. However, in many cases the measurements for samples baked in the hearth and/or in the kiln are very close. The highest magnetic enhancement was always achieved in the double-chamber kiln but only in the parts farthest from the entrance. The reheating increases (except for one clay) and homogenizes the magnetic properties of the kiln samples but this pattern is not systematically observed for the hearth. Magnetically soft minerals dominate. Presence of a high-coercivity carrier (probably hematite) is supposed for three clays single-baked in the hearth and the single-chamber furnace (but only when the samples were placed in the parts with the most oxygen access). During the multiple experimental firing, some samples disintegrated in different extent.</p><p>This study is funded by the grant KP-06-N30/2 from the Bulgarian National Science Fund. The support by Russian Foundation of the Basic Research grant 19-55-18006 is also acknowledged.</p>

Technology and organization of black pottery production on the north coast of Peru

Not all «black» pottery was produced in the same manner just as their social and symbolic uses and reasons for production varied a good deal. Nor are many examples truly black. The Middle Sicán culture (AD 900-1100) on the north coast of Peru distinguished itself with the perfection and large-scale production of black pottery made of fine paste. Based on our «holistic» study of a Middle Sicán workshop (including experimental firing and detailed chemical analyses of both archaeological and experimental samples), we present a detailed characterization of the blackware production technology and organization. Our study revealed that the glossy Middle Sicán blackware resulted from various factors including firing under strongly reducing conditions in small semi-closed kilns, an even carbon deposition on the vessel surface as well as penetration into the body, and the formation of graphite crystals on the well-burnished surface. Chimú reduced ware, in contrast, is typically made of coarser pastes, not as well burnished, and fired in relatively large “pit kilns” that did not permit a tight control over temperature and atmosphere. We infer that the prestige of the Middle Sicán religion and its art together with the lustrous, truly black appearance of the pottery that had been rarely achieved before played an important role in establishing the popularity of black pottery not only in the Sicán heartland but also much of the coastal Peru.

Gendered Places and Depositional Histories: Reconstructing a Menstrual Lodge in the Interior Northwest

This project considered the deposition history of a burned structure located on the Kalispel Tribe of Indians ancestral lands at the Flying Goose site in northeastern Washington. Excavation of the structure revealed stratified deposits that do not conform to established Columbia Plateau architectural types. The small size, location, and absence of artifacts lead us to hypothesize that this site was once a non-domestic structure. We tested this hypothesis with paleoethnobotanical, bulk geoarchaeological, thin section, and experimental firing data to deduce the structural remains and the post-occupation sequence. The structure burned at a relatively low temperature, was buried soon afterward with imported rubified sediment, and was exposed to seasonal river inundation. Subsequently, a second fire consumed a unique assemblage of plant remains. Drawing on recent approaches to structured deposition and historic processes, we incorporate ethnography to argue that this structure was a menstrual lodge. These structures are common in ethnographic descriptions, although no menstrual lodges have been positively identified in the archaeological record of the North American Pacific Northwest. This interpretation is important to understanding the development and time depth of gendered practices of Interior Northwest groups.

Experimental Firing and Re-firing

Ceramics are by definition inorganic non-metallic materials, formed from a powder and by firing converted to a permanent solid mass. Firing is thus a sine qua non for the creation of a ceramic product. This chapter discusses the mineralogical changes and the changes in physical properties which occur in raw materials during the firing process. Experimental firing (in the laboratory and in the field) is a method used to examine the relationship between the properties of ceramic products and raw materials as well as firing conditions. Re-firing, as opposed to experimental firing, involves the firing of ancient ceramic fragments in the laboratory. This procedure enables ancient ceramics to be classified by the type of plastic raw material used in their manufacture and also provides an estimation of equivalent original firing temperature.

The significance of ricochet marks in finding bullets at the shooting scene and in determining shooter location

The article offers an overview of the ricochet phenomenon. The authors addresses the issue of examining bullet trajectories that have been deflected as a result of coming into contact with different types of obstacles. Ricochet marks are used by forensic experts to determine bullet trajectory, pattern, caliber and shooter location. Finding the ricocheted projectiles is difficult due to the fact that the angles of incidence (impact) and reflection are not equal. This article, devoted to ballistics and ricochet phenomenon, is based on the findings of the study conducted by specialists of the MWD Academy, Volgograd, Russia. The above study involved the use of a small semiautomatic 5.45 mm PSM pistol. Experimental firing was conducted with 5.45 mm pistol cartridges with central ignition (MPC); 2.5 g steel-core bullet; 0.15-0.17 g powder charge (Sf 040 gunpowder); muzzle velocity: 315–325 m/s. The shooting targets involved 16 mm particleboards (DSP) covered with laminate and without laminate, removed from old furniture. The results of 17 experimental firings are shown in this article. For all the firing trials, the muzzle was positioned at a distance of 2 m from the anticipated impact site. Based on the obtained results, it can be inferred that for all the ricochet incidents, the angle of reflection was greater than the angle of incidence. The projectile penetrated the particleboard over a certain distance and exited out the front site. The analysis of findings will in the future serve the formulation of the conclusions about the shooting scene, including finding the projectiles. The authors developed the following sequence of recommended expert activities: determining the type of projectile, trajectory, angles of incidence and reflection, shooter position and finally, the search for a projectile.

Characterization of a new laboratory ceramic product from industrial by-products as raw materials and caustic magnesia as additive

A new ceramic product is introduced by mixing caustic magnesia, produced in the laboratory from pure, high quality magnesite, and natural silt. Bottom ash and red mud, two well known environmentally hazardous industrial by-products, were also added in the mixture. After testing various recipes we concluded that addition of 5% caustic magnesia in the ceramic product greatly enhances its performance. Increase bonding of the ceramic microstructure is attributed to the formation of periclase necks, the concurrent formation of small quantities of amorphous material and the homogeneously distributed pores during the experimental firing of the mixture. Combined X-ray Diffractometry and Scanning Electron Microscopy of the ceramic product revealed the occurrence of unreactive phases, inherited by the raw materials, as well as newly-formed albite and magnesioferrite. Our results show that utilization of by-products may be important and environmental friendly materials in producing low cost ceramic building materials.

Transient Burning Rate Model for Solid Rocket Motor Internal Ballistic Simulations

A general numerical model based on the Zeldovich-Novozhilov solid-phase energy conservation result for unsteady solid-propellant burning is presented in this paper. Unlike past models, the integrated temperature distribution in the solid phase is utilized directly for estimating instantaneous burning rate (rather than the thermal gradient at the burning surface). The burning model is general in the sense that the model may be incorporated for various propellant burning-rate mechanisms. Given the availability of pressure-related experimental data in the open literature, varying static pressure is the principal mechanism of interest in this study. The example predicted results presented in this paper are to a substantial extent consistent with the corresponding experimental firing response data.