Light Gun Research Articles

Effect of modified method based on recoil motion on interior ballistic performance of ultralight high-low pressure artillery

Light gun is of unique application prospect for its low body mass and projectile initial velocity. In order to solve the problem of calculation error caused by the large free recoil velocity of light artillery in traditional interior ballistic model, a more suitable internal ballistic model for ultralight artillery was proposed through the design and test of a light gun, the accuracy of the algorithm was verified. The model described the effect of the recoil motion of the gun on chamber pressure and projectile acceleration travel, which made the calculation result more accurate when the gun mass was lighter. Compared with the experimental data, the errors of the calculation results using the improved algorithm were 2.90 % and 0.33 % respectively, while that using the traditional algorithm were 20.38 % and 10.02 % respectively. At the same time, the extended calculation was carried out to analyze the impact of the buffer device on the interior ballistic performance. The result showed that the lighter the gun, the greater the improvement brought by the buffer device under the same mass and recoil resistance. When the mass of the projectile and the gun was both 3 kg, the resistance of 70 kN could increase the velocity of projectile by 16.2 %. Furthermore, the internal ballistic elements of the traditional algorithm and the improved algorithm were calculated respectively under the same working conditions. It was found that when the mass of the gun is 8.567 times the mass of the bullet, the error of the two algorithms was less than 1 %, and the error increased gradually with the mass ratio of gun and projectile decreasing.

Comparison of Blue Light Blocking Effects of Tips and Tinted Lenses for Dental Light Curing Machines

Background/Objectives: This study aimed to examine the blue-light blocking effect according to the curing light tip and the color of the protective eyeglass lens for the operator’s eye protection.Method/Statistical Analysis: The transmittance of light with a wavelength between 200 and 900 nm was measured three times at 1.8 nm intervals using a UV-vis spectrophotometer (LAMBDA 265, Perkinelmer, Inc.). Then the average values obtained were compared for analysis. The visible- and blue-light transmittances of all the tips and tinted lenses were examined, and the ratios of blue light in the transmitted visible light were analyzed to compare the blue-light blocking effects.Findings: The transmittance of visible light with a wavelength between 380 and 750 nm was highest in the yellow lens (60.58%), followed by company B’s tip (55.23%), company A’s tip (51.46%), the orange lens (47.48%), company C’s tip (41.53%), and the red lens (41.00%). The blue-light transmittance was 0.14% in company A’s tip for the curing light gun, 0.75% in company B’s tip, and 0.12% in company C’s tip, which were all very low. Among the tinted lenses, the orange lens had the lowest blue-light transmittance (0.20%), the red lens had a blue-light transmittance of 6.59%, and the yellow lens had the highest blue-light transmittance (12.53%). For the analysis results of the ratio of blue light in the transmitted visible light, it was 0.27% for company A’s tip, the best blue-light blocking rate, and 20.68% for the yellow lens, the worst blue-light blocking rate. The ratios of blue light in the transmitted visible light for companies B and C’s tips were 1.35 and 0.29%, respectively, showing that they have a good blue-light blocking effect.Improvements/Applications: The curing light tips and orange lens used for the analyses in this study showed a blue-light blocking effect. In the case of blue-light blocking by tinted lenses, further studies are required because the blocking rate may vary depending on the lens tint concentration.

“Sweat a little water, sweat a little blood”: A spectacle of convict labor at an American amusement park

This article examines a representation of convict leasing in an unexpected and seemingly inconsequential place—an amusement park. Located in Branson, Missouri, the popular 1880s-themed Silver Dollar City proudly claims to offer historical education and entertainment through “realistic” constructions of the past. One of the park’s oldest and most popular attractions is the Flooded Mine ride, where park guests travel in “mine carts” through a depiction of a flooding mine, trying to “help the sheriff” by shooting laser light guns at kitschy animatronic convict laborers who are trying to escape. We first examine the Flooded Mine as a unique form of penal spectatorship, arguing that riders are able to enjoy the lighthearted mockery of the convict laborers’ suffering through a process of moral disengagement. Second, we use the lens of collective memory in an endeavor to expose the processes of remembering and forgetting at work in Silver Dollar City. We argue that the simulations of the past constructed in the park are not an apolitical platform for entertainment, but rather work to produce a narrative that perpetuates a kind of white nostalgia that erases black suffering. While ostensibly displaying a story of convict labor, the Flooded Mine depicts all the prisoners as white men, effectively performing an historical erasure of chattel slavery and its transmutation into convict leasing. By obscuring the incalculable pain produced by convict leasing and incarceration, the dissimulation allows riders to avoid any ethical engagement with these systems of racialized control.

A late medieval or early modern light gun barrel from the Castle Museum in Malbork\u2014typology, technology of manufacture and identification of the smelting process

The paper discusses a gun barrel of a possibly late 15th-early 16th c. date from the collection of the Castle Museum in Malbork (Marienburg), Poland (MZM/468/MT). The barrel was originally part of a hand-held gun (a hackbut?) and was later converted into a light cannon. The barrel was made from unevenly carburised soft steel (c. 0.1–0.2% C). Both metallographic examinations and the analysis of slag inclusions with the use of multivariate statistics suggest that the metal in the barrel was manufactured using the direct (bloomery) smelting process.

Damage Distribution of High Purity Aluminum under the Impact Loading

Knowledge of damage distribution is important and essential for understanding the dynamic failure behavior of solid material under the high velocity impact. For the High Purity Aluminum (99.999%), disk sample was shock impacted by a light gun and its damage distribution has been carefully characterized. The recovered sample was cut symmetrically along the impact direction and the damage on the cross section has been statistically studied. Unlike the previous work as Lynn Seaman et al. reported, a new computation treatment has been established in terms of the Schwartz-Saltykov method, which gives an easy and simple transformation from the two-dimensional size distribution to three-dimensional size distribution. We demonstrated the variation of damage distribution of High Purity Aluminum under different dynamic tensile loading, and discussed the damage evolution characteristics associated with the micro-voids nucleation, growth and coalescence. Results provide physical basis for the theoretical modeling and numerical simulation of spall fracture.

Microstructural Evolution in Void Coalescence Induced by Plate-Impact Loading in Ultrapure Aluminum

The evolution of microstructure and the mechanical response of ultrapure aluminum subjected to plastic deformation using plate-impact loading was investigated. For the High Purity Aluminum (99.999%), disk sample was shock impacted by a light gun. Observations by transmission electron microscopy reveal that the inside of the early voids consists of nanometer aluminum; it is proposed that they are the result of recrystallization occurring during localization. And some texture may come from the high temperature annealing the secondary grain crystallization behavior and crystallization when the tensile stress effect. This discovery is helpful to the study on the mechanism during the early stage of void nucleation and growth which produced by tensile fracture.

Dynamic properties and microstructural behavior of pure iron below and above shock induced α↔ε phase transition

The study of dynamic damage and fracture of iron has been undertaken below and above phase transition by series of time resolved experiments using both light gas launcher and powder gun. Shock wave tests were conducted by symmetrical impacts of high purity iron. To reveal the material behavior we have done shock experiments where the target is covered with a window in order to limit release amplitude and to avoid specimen fragmentation. Metallurgical analysis of soft recovered samples yields information about damage and fracture processes related to thermo-mechanical loading paths. Tests conducted without window allow studying effects of both phase change and release transition. Optical and SEM characterizations lead us to observe several modes of damage: brittle, ductile diffuse with void growth and heavily localized smooth one. These figures are related with rarefaction shock waves occurrence or interfaces between transformed and not transformed iron. Simulations are performed with the ID to compare experimental data with numerical results. We explain post-mortem observations by the complex shock wave structure interactions: P1 and P2 shock fronts associated with some corresponding shock release during unloading stages.

The early years of aerodynamics ranges, light-gas guns, and high-velocity impact

The age of supersonic flight began at the end of the 19th century when the inventions of smokeless powder and high strength steel enabled an increase in gun velocities to supersonic speeds. However, neither theory nor experiment were available at this time for the science of supersonic flight. The approach being taken then was to record the flight of the body and to compute the forces from its motions, but, unfortunately, unsolved problems in instrumentation stood in the way. The author was assigned the task of solving these problems at the Army's Ballistic Research Laboratories in 1940. His success in this endeavor led to the development of an apparatus, called an “Aerodynamic Range”, for recording the projectile's flight and, hence, determining the aerodynamic forces. World War II had started by this time, and the Aerodynamics Range was put to work immediately measuring the aerodynamic characteristics of gun-fired projectiles, bombs, rockets and some guided missiles. The “cold” war started right after the “hot” war and with it came a new challenge in the form of the InterContinental Ballistic Missile armed with an atomic explosive warhead. Aerodynamic Ranges, which had been built in various laboratories by this time, were put to work on impact tests to determine the lethality of kinetic energy weapons in countering the ICBM threat. In addition, the moon landing program had been started and tests were needed to evaluate the effects of meteorite impact on the lunar surface. Implementing these new programs required a gun capable of launching projectiles at the re-entry and meteoroid velocities of 8 to 10 km/s. The development of a new design of a two-stage high-velocity gun had been started at the Colorado School of Mines, a gun called a “light gas gun” because it used hydrogen as the propellant of its second stage. The author and others continued with its development until a design had been evolved capable of firing projectiles at the required velocities. The gun was then put to work in Aerodynamic Ranges on the assigned tasks of kinetic energy weapon lethality and meteoroid impact.The Early Years paper is an account of the trials and errors in the initial developments of Aerodynamic Ranges and High-Velocity Light Guns and the beginnings of research in high-velocity impact. It is not a formal research paper. Rather, it is an anecdotal account of the events taking place at the starts of these new programs to give the reader a feeling for the ambiance of the times with just enough technology thrown in for credibility. In a sense, telling about the successes and failures of The Early Years belongs with Kipling's verse: “To meet with Triurnph and Disaster and treat these two Impostors just alike”.

Dynamic structural loading using a light gas gun

A light gas gun was used to dynamically load models of the wall sections typical of those used in the construction of buried structures. Scaling of the loading time history is addressed, and the appropriate nondimensional parameters for the loading and the model structural characteristics are defined. Scaling is simplified by use of structural materials for the models which have a yield strength and material moduli close to those found in prototype structures. Methods for producing the desired loading by using a light gun are investigated, and reasonable accuracy and flexibility in achieving the desired loading time history is demonstrated. Experimental results are given for the loading conditions and the failure mode that occurs when the model wall section is breached. The loading conditions to produce failure in the model are reduced to nondimensional form and compared to results from prototype field tests, also in nondimensional form. The resulting nondimensional data are used to evaluate the suitability of the light gun to dynamically simulate ground shock loading as well as to investigate failure criteria.

The Whirlwind computer project

The authors describe how they led the development of the Whirlwind I (WWI) digital computer and its evolution into the SAGE (Semi-Automatic Ground Environment) air-defense system for North America. The project from 1945 through 1956, beginning at a time when no general-purpose, high-speed, electronic computer existed, was from the start dedicated to performance and reliability suitable for real-time control. After several shifts in objectives, Whirlwind became an experimental system for demonstrating that a digital computer could analyze the flow of radar data and generate control orders for fighter-plane interceptions of bombers. The resulting successor computers, the AN/FSQ-7, were installed in a network across the United States and Canada in the late 1950s. The SAGE System control centers were in operation about 25 years and demonstrated a 99.8% up-time reliability. In the Whirlwind Project, vacuum tube life was raised from 500 hours to 500000 hours, marginal checking allowed the automatic detection of aging and drifting of electronic components before they reached the point of failure, random-access magnetic-core storage was invented and developed to become the industry standard computer memory for more than two decades, synchronous parallel logic was used, computer-driven cathode-ray tube displays were used for the first time, light guns were used to permit an operator to identify displayed images to the computer for action, and multiple displays were time-shared between different operators. >

Heart‐rate and blood‐pressure response in medium‐artillery gun crews

A pilot study of the effect of firing the L118/119 British light gun on the heart rate and blood pressure of crewmen who were wearing EAR ear-plugs was carried out. The firing took place on two successive days, with a higher (louder) charge being used on the second day. Each day 40 rounds were fired from each of two guns which were placed 7 m apart. The results suggest that an increase in heart rate of 10%-30% occurs which is attributable to the noise and which does not habituate to successive firings, and that an acute rise in blood pressure may have been associated with the firing of the higher-powered charge. It is considered that these preliminary observations warrant further, controlled experimentation with a larger number of subjects and improved methods of monitoring blood pressure levels.

Learned helplessness: not dependent upon cognitions, attributions, or other such phenomenal experiences.

Subjects shot a light gun at a target with a photorecepter cell in the bull's-eye, with the only information regarding their accuracy being provided by reinforcing tone signals. Half the subjects received reinforcers contingent upon their hits. The others were yoked to the contingent subjects, receiving non-contingent reinforcers in the same patterns. Experiment 1 compared contingent or noncontingent positive or aversive reinforcers in their effect on subsequent anagrams performance. Phenomenal experiences, such as cognitive awareness, attributions, and moods, were assessed. Subjects exhibited a strong helplessness effect independent of their phenomenal experiences. In Experiment 2 the independent variables of contingent/noncontingent reinforcement and awareness of noncontingency were manipulated orthogonally by informing half the subjects that their reinforcement had been noncontingent in the target-shooting. Actual noncontingency produced a strong helplessness effect whereas “awareness of noncontingency” did not.

Tracking and Display of Earth Satellites

In a new method of displaying the predicted paths and real-time positions of artificial earth satellites, cathode-ray tubes are used with two types of map overlays: orthographic projection and Mercator projection. Functions to match these projections are generated electronically. Auxiliary satellite information is cataloged and made available through "light gun" interrogation of the satellites displayed on the CRT. The display and orbit simulator can be used as an integral part of a live tracking system. A mathematical derivation of the subsatellite path on the orthographic projection is given.

Heavy Guns and Heavy Shells Versus Light Guns and Light Shells, with Some Remarks on the Armament of Her Majesty's Ships “Victoria,” “Sanspareil,” and “Benbow.”

Heavy Guns and Heavy Shells Versus Light Guns and Light Shells, with Some Remarks on the Armament of Her Majesty's Ships “Victoria,” “Sanspareil,” and “Benbow.”