Showing papers on "Projectile published in 2002"

Projectile firing device using liquified gas propellant

Abstract: Rifle (1) comprises barrel (2) and loading means (15) for introducing a projectile from magazine (7) into breech (4). The projectile is propelled by a compressed gas propellant initially stored as a liquid in canister (10). The liquid is heated to a super critical state in chamber (8) by heating element (12) to induce a phase change such that the liquid becomes a highly dense gas. The phase change from liquid to gas provides the energy required to expel the projectile at high velocity from rifle (1), regardless of the ambient temperature. The propellant is preferably CO2 which is heated to 31.06 °C. Rifle (1) produces minimal noise and no heat signature, making it suitable for military and stealth purposes. A pistol and launchers for grenades or mortar bombs are also disclosed. Another version can launch low earth orbit satellites or payloads.

Model Predictive Lateral Pulse Jet Control of an Atmospheric Rocket

Abstract: Uncontrolled direct fire atmospheric rockets exhibit high impact point dispersion, even at relatively short range, and, as such, have been employed as area weapons on the battlefield To reduce the dispersion of a direct fire rocket, the use of a small number of short-duration lateral pulses acting as a control mechanism is investigated A unique control law is reported that combines model predictive control and linear projectile theory for lateral pulse jet control of an atmospheric rocket The impact point in the target plane is directly controlled Through simulation, this model predictive flight control law is shown to efficiently reduce direct fire rocket dispersion A parametric trade study on an example rocket configuration is reported that details the effect of the number and amplitude of individual pulse jets, as well as the effect of the flight control system computation cycle time

Antiproton stopping at low energies: confirmation of velocity-proportional stopping power.

Abstract: The stopping power for antiprotons in various solid targets has been measured in the low-energy range of 1-100 keV. In agreement with most models, in particular free-electron gas models, the stopping power is found to be proportional to the projectile velocity below the stopping-power maximum. Although a stopping power proportional to velocity has also been observed for protons, the interpretation of such measurements is difficult due to the presence of charge exchange processes. Hence, the present measurements constitute the first unambiguous support for a velocity-proportional stopping power due to target excitations by a pointlike projectile.

Impact Testing and Analysis of Composites for Aircraft Engine Fan Cases

Abstract: The fan case in a jet engine is a heavy structure because of its size and because of the requirement that it contain a blade released during engine operation. Composite materials offer the potential for reducing the weight of the case. Efficient design, test, and analysis methods are needed to efficiently evaluate the large number of potential composite materials and design concepts. The type of damage expected in a composite case under blade-out conditions was evaluated using a subscale test in which a glass/epoxy composite half-ring target was impacted with a wedge-shaped titanium projectile. Fiber shearing occurred near points of contact between the projectile and target. Delamination and tearing occurred on a larger scale. These damage modes were reproduced in a simpler test in which flat glass/epoxy composites were impacted with a blunt cylindrical projectile. A surface layer of ceramic eliminated fiber shear fracture but did not reduce delamination. Tests on 3D woven carbon/epoxy composites indicated that transverse reinforcement is effective in reducing delamination. A 91 cm (36 in.) diameter full-ring sub-component was proposed for larger scale testing of these and other composite concepts. Explicit, transient, finite element analyses indicated that a full-ring test is needed to simulate complete impact dynamics, but simpler tests using smaller ring sections are adequate when evaluation of initial impact damage is the primary concern.

2-d projectile trajectory corrector

Abstract: A device and a method of adjusting a trajectory of a projectile in flight includes increasing projectile drag to effect a downrange correction and altering the yaw of repose to effect a cross range correction. A method of a vernier correction to the trajectory is included.

N-body simulations of planetesimal evolution: effect of varying impactor mass ratio

Abstract: We present results from direct N-body simulations of collisions between gravitational aggregates of varying size as part of a study to parameterize planetesimal growth in the Solar System. We find that as the ratio of projectile to target mass departs from unity, the impact angle has less effect on the outcome. At the same time, the probability of planetesimal growth increases. Conversely, for a fixed impact energy, collisions between impactors with mass ratio near unity are more dispersive than those with impactor mass ratio far from unity. We derive an expression for the accretion probability as a function of mass ratio. For an average mass ratio of 1:5, we find an accretion probability of ∼60% over all impact parameters. We also compute the critical specific dispersal energy Q*D as a function of projectile size. Extrapolating to a projectile size of 1 m with a 1-km target, we find Q*D=103−104 J kg−1, in agreement with several other collision models that use fundamentally different techniques. Our model assumes that the components of each gravitational aggregate are identical and indestructible over the range of sampled impact speeds. In future work we hope to incorporate a simple fracture model to extend the range of applicable speeds and we plan to implement our results in a large-scale planetesimal evolution code.

Projectile and target ionization in MeV u-1 collisions of Xe ions with N2

Abstract: Experimental cross sections are presented for single and multiple electron stripping from Xe18+ projectiles in collisions with N2 at energies 2.0-9.3 MeV u-1. The data are compared to 2-30 MeV u-1 n-body classical trajectory Monte Carlo calculations that explicitly include electrons on both centres. Two-centre electron-electron (e-e) and electron-screened nuclear interactions contribute to the ionization reactions. The computations are in reasonable accord for the total stripping cross section but underestimate the higher stages of multiple electron loss. An energy deposition model gives improved agreement with experiment. The energy dependence of the total stripping cross section is close to E-0.5. Calculations are also presented for target ionization by Xe+, Xe8+ and Xe18+ at 10 and 20 MeV u-1. Projectile and target ionization cross sections are found to be comparable. Cross sections for projectile stripping by ionized targets are also calculated and found to be relatively insensitive to the ionization stage of the target. This latter observation is attributed to the compensating contributions between the two-centre e-e and electron-screened nuclear interactions.

Projectiles possessing high penetration and lateral effect with integrated disintegration arrangement

Abstract: A highly effective and also inert active penetrator, an active projectile, an active airborne body or an active multipurpose projectile with a constructively adjustable or settable relationship between penetrating power and lateral effect. The end ballistic total effect which is obtained from the penetrating depth and covering the surface or stressing of the surface is initiated in an active case by means of a releasable arrangement or installation which is independent of the position of the active body.

Pneumatic projectile launching apparatus with partition apparatus and opposed-piston regulator

Abstract: An improved pneumatic launching apparatus is disclosed having both a partition apparatus for enabling a projectile, such as gelatinous-filled capsules used in paintball, to be loaded and readied for expulsion without applying mechanical force and an improved venting-pressure regulator. When the partition apparatus is in a withdrawn, or open, position, an aperture is exposed to allow a projectile of complimentary size and shape to drop into the firing chamber. The shape of the partition is such that a next projectile is gently cradled and separated from the firing chamber during a closing movement. Further, the partition preferably creates a seal that significantly inhibits the escape of pressurized gas during a firing operation. The venting-pressure regulator utilizes opposed pistons with an escape mechanism to allow venting to occur without requiring a separate adjustment.

Energy Partitioning in Collisions of Slow Polyatomic Ions with Surfaces: Ethanol Molecular Ions on Surfaces Covered by Self-Assembled Monolayers (CF-SAM, CH-SAM, COOH-SAM) †

Abstract: Energy transfer in ion-surface interactions between ethanol molecular ion and self-assembled monolayers formed by perfluoro-hydrocarbon (CF-SAM), hydrocarbon (CH-SAM), and hydrocarbon with terminal -COON group (COOH-SAM) C 1 1 or C 1 2 chains were investigated over the incident energy range of 11-32 eV for several incident angles. Mass spectra and translational and angular distributions of product ions were used to determine distributions characterizing the partitioning of incident energy of the projectile ion into the internal excitation of the projectile, product ion translational energy, and energy absorbed by the surface. For the CF-SAM, the fraction of energy transformed into internal energy of the projectile had a maximum at about 17% of the projectile ion incident energy and did not depend on the incident angle between 40° and 80° (with respect to the surface normal); the fraction of energy in product translation was for the incident angle of 60° (measured at the product ion angular maximum) about 37%. For the CH-SAM and COOH-SAM and incident angle of 60°, the respective fractions were (peak values) 5-6% into internal excitation of the projectile, 27-30% into product translational energy, and about 64-68% absorbed by the surface, very similar as those for collisions with a hydrocarbon-covered stainless steel surface, investigated earlier.

Criticality for stabilized oblique detonation waves around spherical bodies in acetylene/oxygen/krypton mixtures

Abstract: We have experimentally studied self-sustained oblique detonation waves around projectiles as part of a fundamental investigation of the application of an oblique detonation wave engine and a high-efficiency detonation wave combustor as a power generator. In previous papers we used optical observation to clarify the fluid-dynamic structure of self-sustained oblique detonations stabilized around cone-nosed projectiles. In this study we investigated the criticality for detonation waves. The first expression of the criticality was a mean-curvature coefficient, a rate between a detonation cell width and a mean-curvature radius in which the normal velocity component was the Chapman-Jouguet (C-J) velocity, of 5.03. The mean-curvature coefficient was constant and did not depend on the type of fuel mixture (H 2 /O 2 /Ar or C 2 H 2 /O 2 /Ar), initial mixture pressure, projectile diameter, projectile velocity, or diluent mole fraction. We obtained a more accurate mean-curvature coefficient for stabilized, oblique detonation around symmetric spherical bodies in highly krypton-diluted acetylene/oxygen mixtures that have extremely low C-J velocities. The meancurvature coefficient of 7.8 was determined to be the most important value for stabilizing the self-sustained oblique detonation waves around multidimensional bodies. Based on, experimental results obtained at high-and low-projectile-velocity ranges, it may be concluded that a lower-velocity projectile can stabilize a self-sustained oblique detonation wave more effectively than can a higher-velocity one. In the high-projectilevelocity region, the experimental critical condition is inconsistent with Lee's detonation initiation theory, We propose a semiempirical criticality, equation for the stabilization, which was the secondary expression of the criticality and identical with present and past experimental results.

Simultaneous projectile-target ionization: a novel approach to (e, 2e) experiments on ions.

Abstract: A kinematically complete experiment for simultaneous ionization of a projectile and target has been performed for 3.6 MeV/u C2+ on He collisions measuring the final vector momenta of the He1+ recoil ion and of two electrons (projectile, target) in coincidence with the emerging C3+ projectile. The feasibility of an event-by-event separation of the various reaction channels, among them the ionization of C2+ by the interaction with a quasifree target electron, is demonstrated in agreement with six-body classical trajectory Monte Carlo calculations, paving the way to kinematically complete electron-ion scattering experiments.

Numerical simulation of the ram accelerator using a new chemical kinetics mechanism

Abstract: Computational fluid dynamics (CFD) solutions of the full Navier-Stokes equations, including finite-rate chemical kinetics, are used to numerically simulate the reacting in-bore flowfield for a 90-mm (bore diameter) ram-accelerator projectile propulsion system. In this system a gun tube is filled with a high-pressure gaseous mixture of hydrogen, oxygen, and nitrogen. An axisymmetric projectile is launched into this tube, and rails are attached to the tube wall to ensure projectile centering. The shock system that develops around the projectile, along with boundary layers on the projectile and tube surfaces, ignites the mixture on or near the projectile afterbody. The resulting pressure imbalance on the projectile generates thrust. Numerical predictions of this pressure field can be used to evaluate the thrust efficiency of the system, i.e., the projectile design combined with the chemical composition of the propellant gas. Comparison of the predicted pressure field and the measured pressure data is used to judge the accuracy of the CFD code. The choice of chemical kinetics mechanism used in the CFD code is of critical importance in achieving an accurate numerical simulation of the ram accelerator.

Modeling and simulation of progressive penetration of multilayered ballistic fabric shielding

Abstract: In this paper a simulation technique is developed to estimate the number of ballistic fabric sheets needed to stop an incoming projectile. Such sheets are free of any fortification by a resin. The computational approach is designed so that it can be easily implemented by a wide audience of researchers in the field, without resorting to more involved finite element formulations. This is achieved by taking advantage of the intrinsic characteristics of such fabric structures. Since the deformations of the fabric are (a) finite, (b) nonlinearly inelastic due to progressive fiber degradation and (c) dynamically coupled to the projectile, the system is highly nonlinear. A temporally adaptive, iterative scheme is developed to solve the system. Theoretical issues pertaining to convergence of the algorithm are investigated. Large-scale 3-D numerical examples are then given to illustrate the approach in determining the number of sheets needed to stop a projectile.

Artillery gun with a heavy weapon arranged on a support vehicle

Abstract: An artillery gun having a weapon disposed on a carrier vehicle is provided and comprises a first module, containing the weapon and mounted on a gun mount and also containing at least a portion of an automatic projectile feed mechanism. A second module contains further portions of the projectile feed mechanism. A standby member disposed to the rear of a projectile transporter of the feed mechanism is displaceably guided and can be disposed in a transfer position parallel to a charger disposed on a free end of a projectile transfer arm of the first module. A third module is provided and is embodied as a munitions magazine in which are stored upright projectiles that are adapted to be grasped via a projectile transporter and, accompanied by rotation and alignment, are conveyed via the standby member and charger into a region at the rear of the end of the weapon and to be raised into a loading position. At least one fourth module forms the carrier vehicle.

Subsonic cartridge for gas-operated automatic and semiautomatic weapons

Abstract: A subsonic cartridge that enables a conventional automatic or semiautomatic weapon to fire a projectile at a subsonic velocity and cycle the weapon to eject the spent cartridge case, without the sonic report characteristic of supersonic projectile velocities. The cartridge includes a case having a tubular shape with an open end oppositely disposed head, and a bore therebetween. The head of the case includes a primer cavity, a web separating the primer cavity from the bore, and a flash hole through the web. A primer is stored within the primer cavity, and projectile is disposed within the bore so as to close the open end of the cartridge case. A charge cavity is delimited within the bore between the web and the projectile. The charge cavity is sized and shaped to contain a limited amount of propellant charge that propels the projectile from the cartridge case at a subsonic speed.

An Estimate for Mass Loss From High Velocity Steel Penetrators

Abstract: Analytical models of the penetration process focus on estimating depth of penetration based on target density, target strength (sometimes associated with the unconfined compressive strength of the target for geological targets), the areal density of the penetrator (W/A), and the impact velocity. In this paper, an expression for work is used in conjunction with thermodynamic considerations to devise a simple estimate for mass lost by a high velocity projectile during the penetration process. The result shows that the mass loss is directly proportional to the tunnel length and the target shear strength. The constant of proportionality is not easy to deduce, however, in that it contains an unusual factor from the work analysis. A method for estimating target shear under high pressure from penetration experiments is introduced.Copyright © 2002 by ASME

Vibrational Excitation, Thermal Nonuniformities, and Unsteady Effects on Supersonic Blunt Bodies

Abstract: We have performed a computational study of the experiments performed by Lowry et al at the Arnold Engineering Development Center In these experiments, an rf discharge is used to weakly ionize a volume of air; then a projectileis e red through this plasma Relativeto the conditionswithout the discharge, theshock standoff distance is observed to increase substantially, and the bow shock becomes e atter We have modeled the rf discharge and the resulting thermochemical state of the air within the discharge region Based on these conditions, the projectile e owe eld wassimulatedto determinewhethertherelaxation of thestored internalenergy causestheobservedshock movement The results indicate that the stored internal energy does not relax fast enough to reproduce the experimental results, and, therefore, vibrational energy storage is not responsible for the observed shock movement We considertwo additional mechanisms to explaintheexperiments: modie cationof theelectrice eld by thepresenceof the metallic projectile, and thermal nonuniformities in theplasma The latter effect appears to provide the best explanation for the observations We have also modeled experiments in which microwave-discharge excited air e ows over a model Unsteady thermal effects in the pulsed discharge can account for most of the observed drag change

Systems and methods for projectile recovery

Abstract: A method and apparatus for trapping projectiles so that the projectiles are not damaged is disclosed An elongated trough is typically filled with alternating layers of a foam substance and a fibrous substance Alternatively, the trough can be filled with just a foam or fibrous substance A projectile launcher such as a gun is connected to the trough and a projectile is shot into the filling substance substantially parallel a longitudinal axis of the trough The trough can be opened and the projectile can be recovered from the filling substance

Supersonic liquid jets: Their generation and shock wave characteristics

Abstract: The generation of high-speed liquid (water and diesel fuel) jets in the supersonic range using a vertical single-stage powder gun is described. The effect of projectile velocity and mass on the jet velocity is investigated experimentally. Jet exit velocities for a set of nozzle inner profiles (e.g. straight cone with different cone angles, exponential, hyperbolic etc.) are compared. The optimum condition to achieve the maximum jet velocity and hence better atomization and mixing is then determined. The visual images of supersonic diesel fuel jets (velocity about 2000 m/s) were obtained by the shadowgraph method. This provides better understanding of each stage of the generation of the jets and makes the study of their characteristics and the potential for auto-ignition possible. In the experiments, a pressure relief section has been used to minimize the compressed air wave ahead of the projectile. To clarify the processes inside the section, additional experiments have been performed with the use of the shadowgraph method, showing the projectile travelling inside and leaving the pressure relief section at a velocity of about 1100 m/s.

Method and apparatus for energy and data retention in a guided projectile

Abstract: Energy (110) and mission data (108) for a guided projectile are transferred from a projectile setter (102) over an inductive interface (118). The projectile may include energy storage element (114) to store the energy and a data storage element (112) to store the mission data. Precision GPS clock circuitry (316) of the projectile may receive power from a capacitive energy storage (304) element during projectile loading until a flight battery (320) is activated. In one embodiment, the capacitive energy storage element (304) includes at least one super capacitor (322) and a gun-hardened capacitor (324). The clock circuitry (316) may receive power from the gun-hardened capacitor (324) if the super capacitor (322) fails during the launching operation. The capacitive energy storage element (304) may include one-way energy transfer elements (326) coupled between the super capacitor (322) and the gun-hardened capacitor (324). A regulator (312) may be coupled to an output of the capacitive storage element (304) to regulate an input voltage to the clock circuitry (316).