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Although underwater submerged launching has been rigorously investigated for decades, there remains a dearth of comprehensive understanding regarding the underwater interior ballistic characteristics for varying barrel lengths. To address this knowledge gap, the present study aims to explore, via numerical simulations, the initial velocity of interior ballistics, projectile drag, and the mechanism of initial flow field formation at the muzzle under various barrel lengths, thereby considering the influence of differing barrel lengths. The five distinct lengths of barrels are expressed as dimensionless ratios of the weight of water column in front of the projectile to the weight of the projectile in order to be more general. Five different ratios of water-to-projectile weight are investigated: 1.0, 1.2, 1.5, 1.8, and 2.0, all possessing identical diameters and evaluated under equivalent launch conditions. Different ratios significantly impact muzzle velocity, with shorter barrels yielding higher muzzle velocities, while ensuring complete propellant combustion. Further investigations indicate that variations in drag constitute the fundamental cause of initial velocity changes. Furthermore, it is observed that barrels of different lengths exhibit identical characteristics at the point of maximum drag. The initial flow field at the muzzle exhibits considerable variations in terms of length, profile dimensions, and intensity. The findings of this study offer valuable insights into exploring the mechanism of submerged launching and will be utilized to investigate the optimal barrel length. [ABSTRACT FROM AUTHOR]

In the era of unmanned war, with the increasing muzzle velocity requirement, the design of gun is significantly restricted by recoil, especially for guns installed on unmanned aerial vehicles. A recoilless gun with combustible cartridge was designed to eliminate recoil and increase projectile velocity, and the influence of main parameters on recoil was studied. First, a design of a recoilless gun with high projectile velocity is proposed based on combustible cartridge case. Next, a classical interior ballistic model is developed during the recoilless gun firing cycle, and the effect of main parameters of interior ballistics on the performance is investigated. Additionally, simple nonlinear fitting formulae are defined to highlight the variation of recoil momentum with the time of interior ballistic model. Finally, numerical simulation results are compared with the test results to validate the feasibility of the design. The experimental results demonstrate that the classical interior ballistic model can be used to accurately analyze the effect of the parameters on the projectile velocity and the recoil reduction efficiency. The projectile velocity of the recoilless gun could raised to 1200 m/s and the recoil momentum could be eliminated almostly. Therefore, the newly designed recoilless gun effectively eliminates the recoil momentum and significantly improves the projectile velocity. The findings should make an important contribution to the field of engineering applications of recoilless gun. [ABSTRACT FROM AUTHOR]

Ballistic resistance is affected by the projectile and armor material used. The character and behavior of the projectile affects its ability to damage and penetrate armor. The velocity, mass and shape of the projectile are the main factors in determining the ability of the projectile to penetrate armor in this case the target plate. Therefore, this study aims to determine and analyze the effect of projectile mass and shape on the velocity with which it penetrates the armor material using a compressed air gun. Armor material as a ballistic test target using carbon steel plate with a thickness of 0.8 mm; 1.2 mm and 1.8 mm. Projectiles of lead materials with different masses and shapes are fired from the air gun under controlled air pressure, set at 2000 Psi, 3000 Psi, and 4000 Psi to provide thrust in the barrel. The plat target is placed at a distance of 5 m from the air gun. Speed gauges are placed after the air gun and after the target plate to determine the projectile's rate before and after passing through the target plate. The test results concluded that the velocity of the projectile ejected from the compressed air gun was influenced by the magnitude of the pressure and the mass of the projectile. The mass of the projectile has a more dominant effect on the velocity of the projectile compared to the amount of pressure applied. Different projectile shapes with the same mass have no significant effect on the velocity. However, the heavier mass projectile outperforms the lighter mass projectile through the target plate. It is required the right combination of velocity and mass of the projectile to be able to penetrate the target plate. [ABSTRACT FROM AUTHOR]

Launching large (> 1 g) well-characterized projectiles to velocities beyond 10 km s - 1 is of interest for a number of scientific fields, but is beyond the reach of current hypervelocity launcher technology. This paper reports the development of an explosively driven light-gas gun that has demonstrated the ability to launch 8-mm-diameter 0.36-g magnesium projectiles to 10.4 km s - 1 . The implosion-driven launcher (IDL) uses the linear implosion of a pressurized tube to shock-compress helium gas to a pressure of 5 GPa, which then expands to propel a projectile to hypervelocity. The launch cycle of the IDL is explored with the use of down-bore velocimetry experiments and a quasi-one-dimensional internal ballistics solver. A detailed overview of the design of the 8-mm launcher is presented, with an emphasis on the unique considerations which arise from the explosively driven propellant compression and the resulting extreme pressures and temperatures. The high average driving pressure results in a launcher that is compact, with a total length typically less than a meter. The possibility to scale the design to larger projectile sizes (25 mm diameter) is demonstrated. Finally, concepts for a modified launch cycle which may allow the IDL to reach significantly greater projectile velocities are explored conceptually and with preliminary experiments. [ABSTRACT FROM AUTHOR]

The wounding potential of a projectile depends on its kinetic energy. The aim of the study was to investigate the deceleration of non-deforming full metal jacket handgun bullets (FMJ) in gelatine blocks of increasing length. The temporary cavity (TC) was visualized using a SA-X2 Photron camera. 126 test shots in 9 mm nominal calibre were fired under strict temperature control conditions (4°C) at small gelatine blocks ranging from 2 to 12 cm in length. The deposited energy was calculated based on the loss of bullet velocity through high-speed video analysis. The length of the TC was measured, when the TC reached its maximum height. The volume of the TC was approximated by a cylinder. Regression analysis showed a linear correlation between the length of the bullet path and the energy transfer. The constant deceleration of the FMJ bullets in gelatine up to 12 cm bullet path was confirmed across various brands and velocity ranges (270–450 m/s). Higher impact velocities correlated with increased loss of energy in the target medium. The shape of the bullet tip influenced the characteristic of deceleration. The volume of the tubular temporary cavity, derived from high-speed video records, was found to be proportional to the energy transferred. The proposed approach might be a valuable tool in advancing wound ballistics research. • Deceleration of FMJ bullets proportional to bullet path in compact target models. • Higher impact velocities resulted in greater loss of energy in the target medium. • The shape of the bullet tip influenced the characteristic of deceleration. • Proportionality of the temporary cavity to the transferred energy. [ABSTRACT FROM AUTHOR]

Geometrically nonlinear vibrations of functionally graded shallow shells of complex planform are studied. The paper deals with a power-law distribution of the volume fraction of ceramics and metal through the thickness. The analysis is performed with the use of the R-functions theory and variational Ritz method. Moreover, the Bubnov-Galerkin and the Runge-Kutta methods are employed. A novel approach of discretization of the equation of motion with respect to time is proposed. According to the developed approach, the eigenfunctions of the linear vibration problem and some auxiliary functions are appropriately matched to fit unknown functions of the input nonlinear problem. Application of the R-functions theory on every step has allowed the extension of the proposed approach to study shallow shells with an arbitrary shape and different kinds of boundary conditions. Numerical realization of the proposed method is performed only for one-mode approximation with respect to time. Simultaneously, the developed method is validated by investigating test problems for shallow shells with rectangular and elliptical planforms, and then applied to new kinds of dynamic problems for shallow shells having complex planforms. [ABSTRACT FROM AUTHOR]

This study conducted high-velocity penetration experiments using conventional ogive-nose, double-ogive-nose, and grooved-tapered projectiles of approximately 2.5 kg and initial velocities between 1000 and 1360 m/s to penetrate or perforate concrete targets with unconfined compressive strengths of nominally 40MPa. The penetration performance data of these three types of projectiles with two different types of materials (i.e., AerMet100 and DT300) were obtained. The crater depth model considering both the projectile mass and the initial velocity was proposed based on the test results and a theoretical analysis. The penetration ability and the trajectory stability of these three projectile types were compared and analyzed accordingly. The results showed that, under these experimental conditions, the effects of these two different kinds of projectile materials on the penetration depth and mass erosion rate of projectile were not obvious. The existing models could not reflect the crater depths for projectiles of greater weights or higher velocities, whereas the new model established in this study was reliable. The double-ogive-nose has a certain effect of drag reduction. Thus, the double-ogive-nose projectile has a higher penetration ability than the conventional ogive-nose projectile. Meanwhile, the grooved-tapered projectile has a better trajectory stability, because the convex parts of tapered shank generated the restoring moment to stabilize the trajectory. [ABSTRACT FROM AUTHOR]