Showing papers on "Projectile published in 1996"

Shooting simulating process and training device using a virtual reality display screen

Abstract: A user friendly shooting simulating process and training system are provided to more accurately and reliably detect the impact time and location in which a projectile shot from a shotgun, rifle, pistol or other weapon, hits a moving target. Desirably, the shooting simulating process and training system can also readily display the amount by which the projectile misses the target. The target impact time is based upon the speed and directions of the target and weapon, as well as the internal and external delay time of the projectile. In the preferred form, the training system includes a microprocessor and special projectile sensing equipment, and the targets and projectiles are simulated and viewed on a virtual reality head mounted display.

Ballistically deployed restraining net

Abstract: A ballistically deployed restraining net system including a projectile, a net (32) packaged in the projectile, a net deployment device (63, 64) for unfurling the net in flight, and a fuze for triggering the net deployment device upon the occurrence of a preestablished criteria such as the impact of the projectile with an object, the expiration of a preestablished time period after launch or upon the projectile reaching a predetermined distance to an object.

Non-lethal projectile for delivering an electric shock to a living target

Abstract: An projectile and method of using same employ a projectile body; an electric circuit housed within the projectile body; a plurality of electrodes, coupled to the electric circuit, for delivering an electrical shock to the target; and attachment means, coupled to the projectile body, for attaching the projectile to the target.

Speed-sensing projectile

Abstract: A speed-sensing projectile such as for example a baseball includes a generally spherical body. An inertial switch is positioned within the body and is actuable between open and closed conditions in response to accelerations of the body greater than a threshold value. A processor also within the body is responsive to the inertial switch and calculates the average speed at which the baseball is thrown over a fixed distance. A visible display on the body is in communication with the processor and displays the calculated speed.

Isospin dependence of intermediate mass fragment production in heavy-ion collisions at E/A=55 MeV.

Abstract: The production of intermediate mass fragments (IMF's) from the four reactions 55A MeV $^{124,136}\mathrm{Xe}$ + $^{112,124}\mathrm{Sn}$ is studied with an experimental apparatus which is highly efficient for the detection of both charged particles and neutrons. The IMF's are more localized in the midvelocity region than are the light charged particles, and the detected multiplicity of IMF's depends linearly on the charge lost from the projectile and increases with the neutron excess of the system. Remnants of the projectile, with very little velocity reduction, are found for most of the reaction cross section. Isotopic and isobaric fragment yields in the projectile-velocity region indicate that charge-to-mass ratio neutralization is generally not achieved but is approached when little remains of the projectile. For all systems, the fragments found in the midvelocity region are substantially more neutron rich than those found in the velocity region dominated by the emission from the projectile. This observation can be accounted for if the midvelocity source (or sources) is either more neutron rich or smaller, with the same neutron-to-proton ratio, than the source with the velocity of the projectile. Taken together, the observations of this work suggest that the intermediate mass fragments are, to a large extent, formed by multiple neck rupture of the overlap material, a process which might enhance the neutron-to-proton ratio of the primary source material and/or limit the size of the sources. This scenario is reminiscent of low-energy ternary fission and one predicted by Boltzmann-Uehling-Uhlenbeck calculations. However, these calculations predict too much velocity damping of the projectile remnant. The calculations improve, in this regard, when the in-medium nucleon-nucleon cross sections and the cost of creating low density material are reduced. \textcopyright{} 1996 The American Physical Society.

Method and apparatus for radial thrust trajectory correction of a ballistic projectile

Abstract: A system for controlling the placement of a gun launched projectile adapted with a radial impulse motor incorporated into the projectile for imparting a thrust subsequent to launching and a receiver incorporated into the projectile for targeting information for determining the projectile trajectory and the projectile roll rate, roll position, and pitch, i.e., vertical reference; and a computer linked to the receiver and the radial impulse motor for determining the projectile trajectory and the projectile roll rate, roll position, and vertical reference time after launch of the projectile and angle of corrective vector to ignite the radial impulse motor to affect the trajectory of the projectile to land the projectile on a desired target.

Ballistic projectile trajectory determining system

Abstract: A computer controlled system determines the three-dimensional trajectory of a ballistic projectile. To initialize the system, predictions of state parameters for a ballistic projectile are received at an estimator. The estimator uses the predictions of the state parameters to estimate first trajectory characteristics of the ballistic projectile. A single stationary monocular sensor then observes the actual first trajectory characteristics of the ballistic projectile. A comparator generates an error value related to the predicted state parameters by comparing the estimated first trajectory characteristics of the ballistic projectile with the observed first trajectory characteristics of the ballistic projectile. If the error value is equal to or greater than a selected limit, the predictions of the state parameters are adjusted. New estimates for the trajectory characteristics of the ballistic projectile are made and are then compared with actual observed trajectory characteristics. This process is repeated until the error value is less than the selected limit. Once the error value is less than the selected limit, a calculator calculates trajectory characteristics such a the origin and destination of the ballistic projectile.

Imaging of Saddle Point Electron Emission in Slow p-He Collisions.

Abstract: The two-dimensional velocity distribution of electrons emitted in 5 ‐ 15 keV p-He collisions has been measured for completely determined motion of the nuclei, that is, as a function of the impact parameter and in a well defined scattering plane. The electrons are emitted preferentially in the scattering plane and in the forward direction. The velocity distributions show sharp structures that vary strongly with impact parameter and projectile velocity. The results are compared to classical trajectory calculations. [S0031-9007(96)01614-6] PACS numbers: 34.50.Fa

Soft steel projectile

Abstract: The projectile is made of a virtually lead free steel alloy containing tellurium. This projectile is more environmentally safe compared to conventional lead bullets. The tellurium in combination with a small amount of lead provides a steel alloy having a high machinability and good lubrication properties, thus reducing frictional wear inside a rifle bore when the bullet is passed therethrough. Additionally, a thin anticorrosive coating may be applied on the bullet. The coating may comprise a metal selected from the group consisting of copper, zinc and nickel. An additional lubricating coating comprising polytetrafluoroethylene may also be applied on the projectile. The projectile has a grooved guide section that is permitted to be deformed by the rifle bore without destroying the rifle bore when the projectile is fired in a rifle.

Plasma-screening effects on semiclassical ionization probabilities for the electron-impact ionization of hydrogenic ions in dense plasmas

Abstract: Plasma-screening effects are investigated on semiclassical ionization probabilities for electron-impact ionization of hydrogenic ions in dense plasmas. The projectile - target interaction Hamiltonian is obtained by an appropriate form of the non-spherical Debye - Huckel model. Semiclassical straight-line trajectory method is applied to the projectile path in order to visualize the ionization probability in dense plasmas as a function of the impact parameter and Debye length. The final state of the ejected electron is represented by a plane wave solution normalized in the energy scale. The plasma-screening effect on the ionization probability is appreciably increased with increasing projectile energy. The maximum position of the ionization probability recedes from the nucleus as the projectile energy increases.

Oblique detonation stabilized on a hypervelocity projectile

Abstract: We present new experimental results demonstrating the initiation and stabilization of an oblique detonation by a hypervelocity projectile Projectiles 25 mm in diameter were launched at nominal velocities of 2700 m/s into stoichiometric H 2 -O 2 -N 2 mixtures at pressures between 01 and 25 bar A critical threshold in initial pressure was found to be required for the establishment of detonations Initiation events similar to DDT in propagating waves were observed after 300 mm of travel in H 2 -O 2 mixtures diluted with 25% N 2 A more direct initiation process was observed in H 2 -air mixtures A stabilized but overdriven oblique detonation was observed in a stoichiometric H 2 -air mixture at an initial pressure of 25 bar The pressure threshold can be explained in terms of competing reaction and flow-quenching effects along a curving streamline in supersonic flow behind a curved shock wave This competition can be characterized by a critical Damkohler number Da 0 , which is inversely proportional to the product of wave curvature κ and reaction zone thickness Δ Only if the reaction zone is sufficiently thin in comparison with the projectile, Da>Da 0 , is it possible to obtain stabilized detonations Otherwise, the reactions quench and the wave splits into a nonreactive shock wave followed by flamelike contact surface The inverse pressure dependence Δ∼ P 0 −1 of the reaction zone length and the scaling of the wave curvature κ∼1/ a with the body radius a implies the standard binary scaling relationship P 0 a =constant for the critical conditions of stabilization for a given mixture composition characterized by a bimolecular rate-limiting step

Comprehensive analysis of the stopping power of antiprotons and negative muons in He and gas targets

Abstract: A comprehensive analysis of the stopping power of antiprotons and negative muons in He and gas targets for projectile velocities (equivalent antiproton energies) ranging from about 0.1 to 10 au (0.25 keV to 2.5 MeV) is performed. Recent experimental data are contrasted with theoretical results obtained from different approaches. The electronic stopping power is evaluated within the coupled-state atomic-orbital method and the distorted-wave Born approximation as well as, for low projectile velocities, within a generalized adiabatic-ionization model that takes into account collisional-broadening effects. The departure of the antiproton stopping power from the proton stopping power (`Barkas effect'), observed for intermediate projectile velocities, is discussed. The contribution to the stopping power arising from energy transfer to the translational degrees of freedom of the target system (`nuclear stopping') is evaluated. Our analysis results in a good understanding of the stopping mechanisms of negative heavy particles in gases, in particular in He. Discrepancies between theory and experiment in the case are attributed to effects of the molecular structure of the target.

Barrel assembly with axially stacked projectiles

Abstract: A barrel assembly (10) having a plurality of projectiles (11) stacked axially within the barrel (12) together with discrete selectively ignitable propellant charges (13) for propelling the projectiles (11) sequentially through the muzzle of the barrel (12) is provided with adjacent projectiles (11) separated from one another by locating means (13) independent of the projectiles. The locating means may be a solid propellant charge (13) located between adjacent projectiles or it may be a rigid casing (122) for the propellant. When subject to an in-barrel load a rear skirt portion of the active projectile (11) is expanded outwardly by the interaction between an inwardly reducing recess (14) formed in the rear end of a projectile and the nested complementary leading portion of the propellant charge (13) or propellant casing (122).

Reacting Flow Simulation for a Large-Scale Ram Accelerator.

Abstract: Computational fluid dynamics solutions of the full Navier-Stokes equations have been used to numerically simulate the reacting in-bore flowfield for the ram accelerator projectile propulsion system. In this system a projectile and obturator are injected at supersonic velocity into a stationary tube filled with a pressurized mixture of hydrocarbon, oxidizer, and inert gases. Flow stagnation on the obturator initiates combustion of the mixture, before it is discarded. A system of shock waves on the projectile, in conjunction with viscous heating, sustains combustion. The resulting energy release, which travels with the projectile, also generates high pressures that impart thrust to the projectile. Numerical simulation utilizing finite rate chemical kinetics have been used to investigate this flowfield. Numerical results are used to visualize the flowfield, predict the effects of variation in system parameters, and predict projectile in-bore velocity.

Ballistic impact response for two-step braided three-dimensional textile composites

Abstract: We are concerned with the ballistic impact response of three-dimensional two-step braided textile composites struck by a 36.1-g hemispherical tip-ended rigid cylindrical projectile. A series of quasistatic punch tests using a hemispherical indentor have been conducted to investigate the progressive damage modes of the target and to obtain the punch load-displacement relationship. In addition, a pneumatic launcher is used to propel the projectile with incident velocities ranging from 70 to 170 m/s. The ballistic limit is experimentally determined to be near 74.1 m/s. Commercially available finite element code (MARC) is incorporated with the constitutive relationship for three-dimensional two-step braided composites and the proposed static penetration model to simulate the dynamic impact response. An energy consideration is applied to predict the projectile's residual (or terminal) velocity. Numerical simulated result based on the static elastic properties of the target tends to overestimate the projectile terminal velocity. When the target's elastic moduli used in simulation are increased by 1.5 times the static values, good agreement is found between the simulated terminal velocities and test results for projectile incident velocities ranging from 70 to 180 m/s.

Detailed mechanism of the unsteady combustion around hypersonic projectiles

Abstract: Flow features of an unsteady shock-induced combustion around projectiles are numerically studied using a finite difference method. The large-disturbance regime of the unsteady combustion, characterized by a low-frequency and high-amplitude oscillation, is investigated by a series of simulations considering an oxygen-hydrogen combustion mechanism under the same condition as the experiment. The time-evolving flowfield is obtained in the simulation, and the mechanism of the unsteady phenomenon is investigated. The mechanism on the stagnation streamline agrees with our previously proposed model using a simplified chemical reaction model. Several detailed features characterizing the large-disturbance regime of unsteady combustion are revealed in the computations, and an improved mechanism is proposed. The grid refinement study is carried out to confirm that the flow features obtained are grid independent and are not fictitious. Nomenclature M = projectile Mach number P = pressure T - temperature t = time V = projectile velocity x = distance T = oscillation period TV = induction time

Observation of expanding vapor cloud generated by hypervelocity impact

Abstract: Observations of the expanding vapor cloud generated by the hypervelocity impact have been carried out. Under usual laboratory conditions, rock or ice materials cannot be vaporized completely. In order to investigate the expansion of a large amount of the vapor by complete vaporization caused by hypervelocity impact, we used a nylon projectile and measured the fundamental quantities of the vapor, that is, the expansion velocity, the shape of the vapor cloud, the temperature, and the light energy, by observing the light radiating from the vapor. The expansion velocity of the leading edge of the vapor is almost constant with time and is about twice that of the isothermal sound velocity, which is defined from the pressure and the density of the nylon projectile after passing of the shock wave. The shape of the cloud is not always hemispherical but depends on the combination of the material of the projectile and target, and impact velocity and angle. Inside the vapor cloud are not only the vapor but also the solid ejecta, which travel with the same velocity as the leading edge of the cloud. The temperature of the cloud in the case of nylon impacting on nylon decreases with the power law exponent of time of −0.04 to −0.2. The light energy radiating from the cloud is about 10−4 to 10−5 times the initial projectile kinetic energy.

Guided artillery projectile and method

Abstract: A guided artillery projectile is provided for use in improving its accuracy while spinning. The projectile includes an artillery shell, a plurality of movable fins, fin actuators for two-dimensional steering, a fin control for the fin actuators, and a guidance unit for the fin control. A method of guiding an artillery projectile is also provided.

Aerodynamically stabilized projectile system for use against underwater objects

Abstract: A projectile (50) is propelled from a location in air, through an air/water interface, and toward a submerged underwater object (24). The projectile (50) includes a forward end (52) that forms a cavitation void (30) around the projectile (50) in water, avoiding water drag on the remainder of the projectile (50). The projectile (50) further includes an outwardly flared or finned rearward end (54) that aerodynamically stabilizes the projectile (50) in air and flare stabilizes it in water, in each case against yaw.

Theory and Practice of Projectile’s Penetration in Soils

Abstract: Experimental studies of soil penetration by low-velocity projectiles stimulated the development of theoretical modeling of the phenomena. We developed a model of vertical penetration of granular soils verified by known experiments and dimensional analysis. The experimental results showed nonmonotonic dependence between projectile deceleration and depth of penetration. Net resistant force was found to be a complicated function of variable deceleration and depth. This force was defined not only with pure dynamic and static components, but also with a mixed component important for interpretation of experimental results. Theoretical analysis of nonmonotonic variation of resistance with depth permits evaluation of static properties of noncohesive material using dynamic characteristics of projectile penetration. An understanding of physical processes governing projectile's deceleration was acquired. Velocity and acceleration are obtained as functions of initial velocity, depth of penetration, and media properties. We show two conditions when peaks of acceleration are observed. The initial peak is due to dynamic characteristics, and the second peak is due to static characteristics of penetration.

Spin stabilized projectile with a payload

Abstract: A spin-stabilized projectile containing a payload is presented. The projectile includes a projectile body with a payload chamber that may be laterally defined by a projectile casing, on top by an axial fixing device for a payload disposed in the payload chamber, and on the bottom, by a dividing wall. The projectile casing may include axial grooves on the inside, which on the contribute to the fixing of the payload and include intended break zones for freeing the payload. Below the dividing wall, an opening charge may be disposed, which includes complete radial contact and is axially spaced apart from the dividing wall by a damping device. The detonation of opening charge causes the projectile casing to immediately split open at the intended break zones to release, by centrifugal force, the payload from the payload chamber. The damping device prevents the payload from being damaged in the region of the dividing wall and prevents the release of the payload from being interrupted.

Computation of the roll characteristics of a finned projectile

Abstract: : The Computational Aerodynamics Branch, Launch and Flight Division has been actively developing the capability to predict the aerodynamics of US Army projectiles using Computational Fluid Dynamics (CFD) techniques. Currently under development is the capability to predict the supersonic aerodynamics of finned projectiles such as kinetic energy (KE) penetrators. In the current research effort, several important aerodynamic parameters which influence the roll characteristics of a fielded kinetic energy projectile (M735) have been predicted using CFD techniques. These parameters include the roll producing moment (at zero spin rate), the roll damping moment, and the equilibrium spin rate, defined as the spin rate for which the net roll moment is zero. Viscous CFD computations have been performed over a range of Mach numbers and spin rates using the US Army's Cray-2 supercomputer located at the Ballistic Research Laboratory. The computed results have been used to benchmark and validate engineering approaches for computing these aerodynamics coefficients.

Double electron capture in collisions up to 1500 keV/amu projectile impact

Abstract: A four-body classical trajectory Monte Carlo method is applied in the study of state selective double electron capture by from an He target, when the interaction between the two target electrons is neglected throughout the collisions The total cross section of this process as a function of the impact energy is calculated and compared with experimental and theoretical values