Showing papers on "Projectile published in 1997"

Cavity dynamics in high-speed water entry

Abstract: A method is presented for modeling the cavity formation and collapse induced by high-speed impact and penetration of a rigid projectile into water. The approach proposes that high-speed water-entry is characterized by a cavity that experiences a deep closure prior to closure at the surface. This sequence in the physical events of the induced cavity dynamics is suggested by the most recent high-speed water-entry experimental data, by results from numerical experiments using a hydrocode, and by an understanding of the fundamental physics of the processes that govern surface closure. The analytical model, which specifies the energy transfer for cavity production as equivalent to the energy dissipated by velocity-dependent drag on the projectile, provides accurate estimates for variables that are important in characterizing the cavity dynamics, and reveals useful knowledge regarding magnitudes and trends. In particular, it is found that the time of deep closure is essentially constant and independent of the i...

Pneumatically operated projectile launching device

Abstract: Pneumatic gun which contains a plurality of chambers in communication with each other including a chamber (1) containing and distributing pressurized gas, a chamber (2) containing a compressed gas storage chamber (11) and mechanisms for filling the storage chamber with gas and releasing gas from the storage chamber to fire the projectile, and a chamber (3) containing mechanisms for loading and launching the projectile. The electrical control unit preferably includes an electrical power source which activates an electrical timing circuit when the electrical switch is closed, and two electrically operated pneumatic flow distribution devices (35, 36) which are sequentially energized by the electrical timing circuit to enable the loading of a projectile for launching and to release compressed gas from the storage chamber (11) to fire the projectile, respectively.

Charge-dependent electronic stopping of swift nonrelativistic heavy ions

Abstract: The stopping of swift nonrelativistic heavy ions has been analyzed theoretically as a function of the projectile charge q{sub 1} Excitation and ionization of target electrons are described within Bohr{close_quote}s classical theory and the limitations toward Bethe{close_quote}s quantal description are outlined For oxygen ions in carbon the Bethe regime is found to be confined to the velocity range where the ion is essentially stripped in charge equilibrium The effect of projectile electrons is taken into account mainly via screening of the Coulomb interaction, but excitation of projectile electrons is discussed briefly The significance of projectile screening hinges on a parameter s that depends on projectile and target parameters and varies substantially over the electron shells of the target Calculated fixed-charge stopping cross sections agree well with measured values in absolute magnitude and in their variation with charge state q{sub 1}{sup 2} scaling frequently has been assumed in the literature A continuous transition is predicted between such scaling and a stopping power that is almost independent of the projectile charge {copyright} {ital 1997} {ital The American Physical Society}

Weapon for immobilization and capture

Abstract: An immobilization weapon of the type which imparts an electrical voltage across a live target using a projectile launched toward the target from a distance, employs a projectile having two connecters. One such connecter extends from the projectile in fixed relation thereto. The other such connecter is launched from the projectile at or near the target to assure proper spacing between the connecters irrespective of the distance to the target. In the preferred embodiment, the secondarily launched connecter is actuated by current through the target when the projectile is in proximity to the impact surface of the target.

Storage ring system and method for high-yield nuclear production

Abstract: A storage ring system and method for high-yield nuclear production of neutrons, isotopes and photons, include a particle supply for generating a beam of projectile or reaction particles, a closed storage ring for containing and recycling the projectile particles, an electron cooling system for stabilizing the projectile particles, and a target for initiating nuclear reactions with the projectile particles so as to generate the desired end-products, with improved efficiency and safety. The invention also provides a plurality of dipoles and/or trim magnets selectively situated around the ring to guide the projectile particles as they circulate within the system. Substantially trapped in the closed storage ring, the particle beam is recirculated inside the storage ring for repeated exposure to the target, until the particles either favorably react with the target or are lost through scattering. As new particles are injected into the storage ring, they merge with previously injected particles circulating the ring, thereby allowing a relatively high intensity beam to develop, even though the input current used to populate the system remains relatively low throughout the operation of the system. Advantageously, the present invention maintains the particle beam within optimal reaction parameters by providing the electron cooling system to stabilize the particle beam.

System and method for locating a trajectory and a source of a projectile

Abstract: A projectile trajectory and source location system and method identifies, calizes, and displays a projectile trajectory relative to one or more stationary objects, such as buildings in an urban environment. The system includes a sensor array and trajectory location calculator that sense conditions generated by the projectile, such as an acoustic signature, and calculate a set of ranges to the trajectory. A ranging system and range comparison calculator measure ranges to one or more stationary objects and compare those ranges to the set of ranges to the trajectory. A display displays the trajectory relative to the stationary objects including unobstructed portions of the trajectory, obstructed portions of the trajectory and the located source of the projectile. A tracking system and dynamic reprocessor track the movement of an observer, dynamically reprocess the relative trajectory location, and update the display of the relative trajectory location in response to the observer's movement.

Non-lethal cartridge with spin-stabilized projectile

Abstract: The invention is a non lethal weapon cartridge comprising a projectile and means for propelling the projectile through a weapon barrel. A munition of this type can be employed by soldiers during operations-other-than-war, such as riot control during humanitarian missions, or by law enforcement personnel when a lethal response is not warranted. The projectile comprises a full-bore projectile body fitted with a compliant nose. The projectile is designed to be spin-stabilized such that it will fly, and impact, nose first, while describing a ballistic trajectory. The projectile is intended to be launched from a rifled weapon tube. The rifling imparts the spin necessary to achieve dynamic stability. The propulsion system utilizes a modern smokeless propellant in combination with a high-low technique to produce consistent interior ballistics.

Dynamic plasma screening effects on semiclassical inelastic electron–ion collisions in dense plasmas

Abstract: In dense plasmas, dynamic plasma screening effects are investigated on 1s→2p dipole transition probabilities for electron-impact excitation of hydrogenic ions. The electron–ion interaction potential is considered by introduction of the plasma dielectric function. A semiclassical straight-line trajectory method is applied to the path of the projectile electron in order to visualize the semiclassical transition probability as a function of the impact parameter, projectile energy, and plasma parameters. The transition probability including the dynamic plasma screening effect is always greater than that including the static plasma screening effect. When the projectile velocity is smaller than the electron thermal velocity, the dynamic polarization screening effect becomes the static plasma screening effect. When the projectile velocity is greater than the electron thermal velocity, then the interaction potential is almost unshielded. The difference between the dynamic and static plasma screening effects is mo...

Bethe theory of stopping incorporating electronic excitations of partially stripped projectiles

Abstract: The Bethe theory for the energy loss of swift charged particles colliding with atomic targets is extended to treat explicitly the case when the projectile has bound electrons. The theory is characterized by taking into account the excitation and ionizations (but not charge exchange) of both projectile and target. As a consequence of the Coulombic character of the interaction between projectile and target, the electronic stopping cross section ${\mathrm{S}}_{\mathrm{e}}$ is split into contributions arising from the electronic structure of the projectile and of the target. In the lower part of the velocity region where this theory is applicable, the electronic structure of the projectile makes an important contribution, of the order 10--20%, to ${\mathrm{S}}_{\mathrm{e}}$. At high projectile velocities, however, this contribution decreases, leaving only the standard Bethe term. The number of electrons bound to the projectile, ${\mathrm{N}}_{1}$, as a function of the velocity of the projectile is calculated using the adiabatic Bohr criterion in conjunction with the Thomas-Fermi model of the atom. We obtain an analytic expression for the total stopping cross section using the Bethe approximation, and we compare the results of calculations of He, Li, and B ions on C and Al targets with experiment.

Low Energy Reactions of Halo Nuclei in a Three-Body Model

Abstract: Low energy nuclear reactions of nuclei with halo structure are theoretically studied in a three· body model in which the projectile is described as the weakly bound state of the halo neutron and core nucleus A time·dependent wave packet method is employed to solve the three·body Schrodinger equation and to calculate reaction probabilities Numerical results with various internal Hamiltonians reveal that the reaction mechanisms depend strongly on the single particle structures of the core and target nuclei The adiabatic dynamics is found to be important when the neutron is bound tightly in the projectile For a weakly bound projectile with halo structure, the fusion probability is found to decrease due to the addition of a neutron

Automatic feeder for projectile gun using compressed gas

Abstract: A portable automatic projectile loading device for use with a gun-like apparatus typically utilizing compressed gas to fire projectiles The device being capable of storing up to 1000 projectiles which are conveniently carried by the user in a coiled flexible hose contained, along with a compressed gas cylinder, in a pack preferably carried on the back The projectiles may be paint, gelatin, or tear gas filled balls that rupture upon impact The device utilizes compressed gas flowing through a flexible hose containing the projectiles to propel the projectiles into the breach of the gun-like apparatus

Backstop system for measuring position, velocity, or trajectory

Abstract: A backstop or target particularly suited for use in athletic applications such as baseball or golf, and which includes a frame from which a flexible net is suspended at its corners and connected to a plurality of linear displacement sensors. As the net is displaced due to the impact of a projectile such as a ball, tension is applied to the cords which in turn move the axially-moveable components of each linear displacement sensor. In one embodiment, the linear displacement sensors utilize a light beam and photoelectric detector to plot the time intervals at which equally-spaced indices on the axially-moveable component pass a predetermined point. This data is used to determine position, velocity, or trajectory of the projectile relative to the initial plane of the net using direct geometric and trigonometric calculations.

Remote sensing apparatus of supersonic projectile

Abstract: A remote targeting apparatus and method comprising surrounding a projectile target with a sensor array, computing projectile impact data, transmitting the data receiving the data at a controller; and displaying information corresponding to the data. RF transmission/reception is performed, most preferably at a frequency of between approximately 902 and 928 MHz, with the controller having RF Faraday cage shielding and collision avoidance being employed to permit multiple sensor arrays to operate in a vicinity of one another. Projectile impact locations within twelve inches of the center of the projectile target are calculated to an average RMS accuracy of less than approximately fifty thousandths of an inch, directly in an orthogonal Cartesian coordinate system. Velocity is also determined via an additional sensor at a predetermined distance from the sensor array which measures a difference in time between the projectile passing the additional sensor and the sensor array. The preferred sensor array has at least two pairs of acoustical sensors, with an additional acoustical transducer orthogonal to the two pairs.

Dynamic screening effects on electron-ion Coulomb bremsstrahlung in dense plasmas

Abstract: Dynamic plasma screening effects are investigated on classical bremsstrahlung in electron-ion Coulomb scattering in dense plasmas. The electron-ion interaction potential is considered by the introduction of the longitudinal plasma dielectric function. The classical straight-line trajectory method is applied to the path of the projectile electron. The differential bremsstrahlung radiation cross section including the dynamic plasma screening effect is always greater than that including the static plasma screening effect. When the projectile velocity is smaller than the electron thermal velocity the dynamic polarization screening effect becomes the static plasma screening effect. When the projectile velocity is greater than the electron thermal velocity the interaction potential is almost unshielded. It is also found that the static plasma screening formula obtained by the Debye-H\"uckel model overestimates the plasma screening effects on the electron-ion Coulomb bremsstrahlung processes in dense plasmas.

Analysis of generator-driven linear induction launchers

Abstract: This paper deals with the analysis and design of high-speed, multi-section, generator-driven, polyphase, linear-induction-type electromagnetic launchers. During a launch, steady state is never reached. Hence, a transient simulation model, based on lumped-circuit parameters, was developed, for purposes of analysis, in earlier work with capacitor-driven launchers. This model, as well as its related computer code, is also applicable to generator-driven launchers. From earlier work, we found that simultaneous energizing of the three phases of generator-driven launchers gives rise to DC current components in the barrel-coils that can cause strong braking forces, especially at the transitions between sections. In this paper, an alternate energizing mode, in which the three phases of the barrel coils are switched on in sequence, phase by phase, with the appropriate phase shifts, is investigated. Numerical results of the transient simulation show that the initial position of the projectile at a section transition at switch-on time, and the switch-on phase angle, significantly influence the performance. With some poorly-chosen initial positions or phase angles, DC components of the currents in the armature can produce very large retarding forces, thus resulting in actual deceleration of the projectile. On the basis of the transient model, simulations were done to search for the optimal switch-on phase angles and initial positions of the projectile. The results show that smoother transitions between sections and higher muzzle velocities can be achieved with these optimal phase angles and initial positions.

Non-lethal projectile

Abstract: The invention discloses a non-lethal projectile. This projectile (1) comprises a longitudinal body (5) with an internal longitudinal striking pin (55) capable of piercing a container (47) of fluid under pressure in a controlled manner in particular by the impact of the projectile (1) on a target. The striking pin (55) comprises an internal passage (59) opening outwards of the body (5) by means of canals (60) provided in a rigid wall (35) integral with the body (5) such that the outlet for the fluid under pressure remains clear even if the impact causes a deformation of the container (47). The fluid contained in the container (47) can thus be released and spread over the target even in such case.

Energy loss of highly charged argon ions at grazing incidence on a graphite surface

Abstract: We have used the time-of-flight technique to measure the energy loss for 51-keV argon ions scattered grazingly from a smooth highly oriented pyrolytic graphite surface. The energy loss has been measured for several impact angles and two charge states, q=2+ and q=16+. Our data indicate that the image charge acceleration in the front of the surface, which increases the effective impact angle of the projectile, affects the energy loss. After correcting for this effect, the energy loss does not depend on the initial charge state of the projectile but increases with increasing the angle of incidence. This indicates a full neutralization of the projectile before it reaches the distance of the closest approach. The experimental results agree approximately with predictions of a modified Firsov model.

Game with rings and target

Abstract: A game having a target and a projectile that is tossed or pitched to the target. The target has a bottom, has a cup generally centered on the bottom, and perimeter sidewalls that are spaced outward from the cup and surround the bottom. The projectile is a disk member that has indicia disposed thereupon to distinguish the projectile from other projectiles. The target may optionally include an anchor to anchor the target to a surface. Further, the projectile may be a washer that is enclosed in a protective layer. The protective layer may define the distinguishing indicia. The sidewalls may also be constructed as hollow walls, having inner and outer portions. The hollow may optionally be filled with a filler material.

Aeroballistic Range Tests of the Basic Finner Reference Projectile at Supersonic Velocities

Abstract: : Free-flight tests were conducted in the Defence Research Establishment Valcartier (DREV) Aero ballistic Range on the Basic Finner reference projectile from transonic to high supersonic velocities. The projectile consisted of four rectangular fins on a cone-cylinder body with a total length-to-diameter ratio of 10.0. Fin cants of 0 deg, 2 deg and 4 deg were imposed. The Mach number range tested was between 1.0 and 4.5. All the main aerodynamic coefficients and stability derivatives were well determined using linear theory, six-degree-of-freedom single- and multiple-fit reductions techniques. The results were also compared with results from other aeroballistic ranges. The fins on the models fired at Mach 4.5 ablated during flight. A dynamic stability analysis showed a Magnus instability at certain Mach numbers and spin rates.

Apparatus and method for calculating muzzle velocity

Abstract: Apparatus for measuring projectile muzzle velocity with an accuracy of ±0.1% is mounted in an easily portable muzzle attachment. It operates in the following manner. A washer shaped permanent magnet is positioned on a projectile body. A position sensor containing two inductive coils is located inside the muzzle. When the projectile is fired, the magnet mounted on the projectile passes through the inductive coils, inducing a voltage in each coil. Each voltage is amplified and then fed into hysteresis and zero crossing comparators corresponding to each inductive coil. The zero crossing comparator detects when the induced voltage crosses zero. The hysteresis comparator will gate out any noise induced zero crossings. The two zero crossings are used to start and stop a digital counter which generates a velocity count signal that corresponds to the velocity of the projectile. Further noise interference rejection is obtained by encasing the muzzle extension in a magnetic metal.

Drag control module for stabilized projectiles

Abstract: A trajectory (range) control device which is designed to fit behind the f of a fin stabilized ballistic projectile for correcting range error The trajectory (range) control device is a self-contained, add-on module, which will screw into the forward portion of the projectile The fuze will then screw into the trajectory (range) control module, which has a small through hole that will coincide with the center of the fuze and the center of the projectile This through hole is intended to provide a channel in which the fuze can detonate the intended booster charge which will in turn ignite the high explosive payload or function the payload of the fin stabilized ballistic projectile The trajectory control device will not make changes to the existing projectile or fuze During the course correction phase, eight spring loaded flare tabs will deploy from the device The flare tabs create a blunt cross-sectional area in front of the projectile, thus creating more drag and effectively slowing the projectile

System for shooting using compressed gas

Abstract: A shooting system providing a barrel with an open forward end and a closed rear end and a projectile containing a propellant under pressure located in the barrel. A wad in the bore has a forward holding member allowing the rearward portion of the projectile to be moved rearwardly in the bore and be longitudinally slidably frictionally fitted in the holding member while the holding member is in sealing engagement circumferentially of and between the barrel and the projectile whereby the projectile is in a loaded state. The holding member also allows the projectile to move forwardly out of the holding member in the firing state. The wad also has a rearward sealing portion in circumferential sealing engagement with the barrel and radially spaced from the rearward portion of the projectile whereby the closed rearward end of the bore, the sealing member, and the projectile form a firing chamber. When the valve is actuated, propellant expands into the firing chamber where it is contained by the closed rearward end of the barrel and the sealing member and applies maximum pressure on the projectile to force it out of the holding member and the barrel thereby firing the projectile. An alternative embodiment provides a barrel with a longitudinally expandable goffered rear end portion forming part of the firing chamber whereby in the firing mode and upon release of the expanding propellant into the chamber, the propellant both expands the goffered section longitudinally and forces the projectile out of the barrel.

Role of projectile electrons in secondary electron emission from solid surfaces under fast-ion bombardment

Abstract: We report on measurements of the number of electrons per incoming projectile emitted from the projectile entrance and exit surfaces of thin carbon foils as function of the projectile atomic number Z (1{le}Z{le}32), incident charge states, and velocities below, near, and above the stopping power maximum The screening of the projectile charge by the projectile electrons reduces the backward electron emission The corresponding reduction parameters have been determined as function of the number of projectile electrons For all ions but protons we note as a general trend that the forward to backward yield ratio R{sub {gamma}} increases with the projectile velocity In addition a pronounced increase of the R{sub {gamma}} with increasing Z is also observed It was found that the increase of the R{sub {gamma}} with Z in the medium velocity region ({approximately}1MeV/u) is not a {open_quotes}nuclear charge{close_quotes} effect, but is simply due to the difference in the incident number of projectile electrons The experimental results are compared to Monte Carlo simulations based on the work by Gervais and Bouffard A reasonable agreement (within 20{percent}) between experimental and calculated results for heavy ions is observed However, the difference is larger for light ions Finally, the results are discussed withinmore » the framework of previously published semiempirical models and the relation between electron yields and the electronic stopping power is elaborated {copyright} {ital 1997} {ital The American Physical Society}« less