Showing papers on "Projectile published in 1999"

Acoustic counter-sniper system

Abstract: A low cost and highly accurate sniper detection and localization system uses observations of the shock wave from supersonic bullets to estimate the bullet trajectory, Mach number, and caliber. If available, muzzle blast observations from an unsilenced firearm is used to estimate the exact sniper location along the trajectory. The system may be fixed or portable and may be wearable on a user's body. The system utilizes a distributed array of acoustic sensors to detect the projectile's shock wave and the muzzle blast from a firearm. The detection of the shock wave and muzzle blast is used to measure the wave arrival times of each waveform type at the sensors. This time of arrival (TOA) information for the shock wave and blast wave are used to determine the projectile's trajectory and a line of bearing to the origin of the projectile. A very accurate model of the bullet ballistics and acoustic radiation is used which includes bullet deceleration. This allows the use of very flexible acoustic sensor types and placements, since the system can model the bullet's flight, and hence the acoustic observations, over a wide area very accurately. System sensor configurations can be as simple as two small three element tetrahedral microphone arrays on either side of the area to be protected or six omnidirectional microphones spread over the area to be monitored. Sensors may also be monitored to a helmet as used with the wearable system. Sensor nodes provide information to a command node via wireless network telemetry or hardwired cables for the command node comprising a computer to effect processing and display.

Numerical Study of Cavitation in the Wake of a Hypervelocity Underwater Projectile

Abstract: The focus of this study is on cavitation in the wake of a high-velocity underwater projectile. A physical model based on the Euler equations is presented in terms of two-phase mixture properties. Mathematical closure is achieved by providing equations of state for the possible thermodynamic states: compressible liquid, compressible two-phasemixture,andcompressiblepurevapor.Fortheoperatingconditionsstudiedhere,allstatesaresubcritical. Theproposedmodelissolvedusingahybridcomputationalschemedevelopedtoaccuratelyresolvepropertyproe les across discontinuities. The model is validated with several one-dimensional test cases that have known analytic solutions. For modeling the hypervelocity underwater projectile, the model is shown to compute unsteady shockwave development as well as the projectile-wake cavitation zone. The model is then used to conduct a parametric study on the affect of e ow and projectile properties on cavitation.

Self-contained interactive play structure

Abstract: A self-contained interactive play structure is provided having an outer housing and a plurality of towers disposed within the housing. A plurality of play media including impact-safe projectile accelerators are disposed throughout the structure. A central targeting area is provided having targets which, when contacted by a projectile, activate desired play effects. A projectile conveyor system supplies projectiles to be shot from the projectile accelerators.

Hypervelocity impact experiments on aerogel dust collector

Abstract: Laboratory hypervelocity impact experiments were conducted to verify the performance of aerogel dust collectors used for gathering meteorolds and space debris in the near-Earth environment and to derive the relationships of various parameters characterizing the projectile with morphology of tracks left by the penetrating projectile in the aerogel collector pad. Silica aerogel collectors of 0.03 g/cm - density were impacted at velocities ranging from 1 to 14 km/s with projectiles of aluminum oxide, olivine, or soda- lime glass, with diameters ranging from 10 to 400/xm. At impact velocities below 6 km/s the projectiles were captured without fragmentation by the aerogel collector and, in many instances, without complete ablation even at 12 km/s. The shapes and dimensions of the penetration tracks left in the aerogel collector were correlated with the impact parameters, and the results permitted derivation of a series of equations relating the track dimensions to incoming projectile size, impact energy, and other projectile parameters. A simplified model, similar to meteor-entry phenomena, was used to predict the trends in experimental penetration track lengths and the diameters of captured projectiles. Solid particles present in the near-Earth environment derive from either natural or artificial origin and are termed "mete- oroids" and "space debris", respectively. Meteoroids are con- sidered to be supplied from comets, asteroids, and planets, and some known as interstellar dust particles or interstellar grains are from outside the solar system (Griin et al., 1993). Since meteoroids are thought to be closely related with the evolution of the solar system, study of these materials provides us with crucial information on the source materials for the solar sys- tem. In situ sampling of meteoroids in space can avoid con- tamination by terrestrial sources, which is unavoidable in sam- pling on Earth. Space debris is the product of normal satellite operations, the deterioration of satellites, and the fragmentation or breakup of satellites (Johnson and McKnight, 1991). It is im- portant to investigate micrometer-to-millimeter-sized debris, the range within which the majority of debris particles lie, because this changes the characteristics of the materials of spacecraft or of the on-board parts after colliding with them. The distribution and composition of small-sized debris are not well known, as these particles are too small to be observed with ground-based telescopes or radars. In situ sampling of dust particles is useful for getting material information on the de-

Fiber reinforced ceramic matrix composite armor

Abstract: An integrated, layered armor structure having multiple layers which alternate in their exhibited characteristics between extremely hard and ductile. The extremely hard layers of the armor structure are designed to shatter an impacting projectile, or pieces thereof, and to fracture in such a way as to dissipate at least a portion of the kinetic energy associated with the projectile pieces and to disperse the projectile pieces and hard layer fragments over a wide area. The ductile layers of the armor structure are designed to yield under the force of impinging projectile pieces and hard layer fragments from an adjacent hard layer. This yielding dissipates at least a portion of the remaining kinetic energy of these pieces and fragments. Pieces and fragments not possessing sufficient kinetic energy to tear through the ductile layer are trapped therein and so stopped.

Failure of a horizontal pressure vessel containing a high temperature liquid: the velocity of end-cap and rocket missiles

Abstract: Many process plant installations include cylindrical vessels which contain high temperature liquids with the remaining space above occupied by vapour or a vapour/gas mixture. If such a pressure vessel were to be ruptured, missiles (i.e. fragments) may be generated and equipment in the vicinity put at risk. There is a particular threat from large missiles. Theoretical models have been developed to describe the peak velocity achieved by end-caps and `rocket' missiles generated by the circumferential failure of a vessel. The end-cap missile model assumes that the action of the escaping vapour/liquid on the end-cap is analogous to a missile driven by a gas jet from a constant pressure source. The `rocket' missile velocities are derived via a simple approximation to the impulse applied to the internal face of the closed end of the `rocket'. Experiments have confirmed the validity of these approaches and upper limit values to end-cap and `rocket' velocities have been defined.

Shock Structure of a Spherical Projectile in Weakly Ionized Air

Abstract: : A test program was undertaken at Arnold Engineering Development Center (AEDC) to investigate previously reported measurements of anomalous shock standoffs in weakly ionized gases by installing an RF plasma generator in AEDC's S1 Hypervelocity Impact Range. The AEDC tests were conducted by firing 9.5- and 19.1-mm-diam spheres in air at velocities in the range 1200 to 1700 m/sec and at pressures in the range 15 to 40 torr. The bow shock shape data were obtained using holographic interferometry techniques. A standoff distance was measured and ratioed to the projectile radius. The data were compared to CFD calculations for a uniform gas temperature. Confirmation of the anomalous shock standoffs was obtained, and efforts were subsequently directed towards separating the effects of ionization from the effects of gas temperature on the shock profile. The temperature was measured by three different techniques (thermocouple, N2(+) emission spectrum, and NO-PLIF); the results appear to be much lower than necessary to explain the measured shock standoffs by uniform gas effects.

Dynamic nonlinear screening of slow ions in an electron gas

Abstract: We have used the ensemble Kohn-Sham method with the local-density approximation to determine self-consistently the dynamic screening cloud around an impurity moving adiabatically through a uniform electron gas with velocity below the Fermi velocity. The asymmetry of the induced field and electronic density caused by the impurity motion is fully taken into account. We discuss the forward-backward asymmetry for the case of bare positive and negative charges as well as for hydrogen atoms. We show that the stopping power of the electron gas varies linearly with the projectile velocity up to velocities close to the Fermi velocity. We study the asymmetry of the bound states, its contribution to the stopping power and the evolution of the binding energy as a function of projectile velocity. Finally, we give a complete derivation of the low energy behavior of the stopping power and the generalization of the Friedel sum rule and oscillations for the case of moving impurities.

Projectile impact location determination system and method

Abstract: An impact location determination system (20) includes a damage resistant strike plate (22) having a planar surface (26) adapted to be impacted by a projectile (28). Pressure sensor assemblies (55) are embedded in the strike plate (22) and detect a pressure disturbance event outwardly propagating as a wave (36) from an impact location (34). The wave (36) propagates through the strike plate (22) at a propagation velocity that is slower than the speed of sound for the strike plate (22). A signal processing circuit (32) measures time difference of arrival figures (196 and 198) between pairs of pressure sensors (140 and 142) and determines the impact location (34) in response to the time difference of arrival figures (196 and 198) and the velocity of the wave (36) through the strike plate (22).

Rapid deployment countermeasure system and method

Abstract: A rapid deployment countermeasure system comprises a base attached to a plurality of tubes which are in fluid communication with at least one deployment module. A guidance bar is attached to the top ends of the tubes, and a guidance shroud is proximate to the outer surfaces of the tubes. The system includes one or more anti-ballistic blankets fixedly attached to the guidance bar, and is erected to form an anti-ballistic barrier upon activation of the deployment modules. A method to reactively protect personnel from the approach of a ballistic projectile by deployment of a countermeasure system prior to arrival of the projectile at the location of the personnel comprises the steps of detecting the approach of the ballistic projectile, discriminating the presence of the ballistic projectile with respect to other moving objects or electronic noise, and activating the countermeasure system in response to discriminating the presence of the ballistic projectile so as to interpose an anti-ballistic barrier between the personnel and the projectile.

Fluid-filled bomb-disrupting apparatus and method

Abstract: An apparatus and method for disarming improvised bombs are disclosed. The apparatus comprises a fluid-filled bottle or container made of plastic or another soft material which contains a fixed or adjustable, preferably sheet explosive. The charge is fired centrally at its apex and can be adjusted to propel a fluid projectile that is broad or narrow, depending upon how it is set up. In one embodiment, the sheet explosive is adjustable so as to correlate the performance of the fluid projectile to the disarming needs for the improvised explosive device (IED). Common materials such as plastic water bottles or larger containers can be used, with the sheet explosive or other explosive material configured in a general chevron-shape to target the projectile toward the target. In another embodiment, a thin disk of metal is conformably mounted with the exterior of the container and radially aligned with the direction of fire of the fluid projectile. Depending on the configuration and the amount of explosive and fluid used, a projectile is fired at the target that has sufficient energy to penetrate rigid enclosures from fairly long stand-off and yet is focused enough to be targeted to specific portions of the IED for disablement.

3-D field analysis in tubular induction launchers with armature transverse motion

Abstract: In this paper the transition between the sections of a generator driven induction launcher is investigated. During the transition a possible mismatch of the currents in the sleeve with the driving coils currents can give rise to strong braking force. If the sleeve is not in coaxial position with the barrels, forces in the transverse direction of motion can produce contacts with the flyway tube. Transverse motion of the sleeve has to be considered. The equations of motion are derived assuming a rigid projectile and a flyway restoring force that is proportional to the local deformation. A full 3-D analysis, required because of the departure from the coaxial configuration, has been performed by means of a computer code based on an integral formulation of the Maxwell equations; the resulting equations are those of an electrical time-varying network. Simulations of the behaviour of the system have been performed to search for the optimal initial position of the sleeve in the second section. The results show that smooth transition between the sections is obtained if the energization of the coils of the second section is done in correspondence with the proper positions of the sleeve. Under these conditions the motion is characterized by the greater muzzle velocity.

Improved projectile tracking system

Abstract: A projectile tracking system (2) for acquiring and precisely tracking a projectile in flight in order to reveal the source from which the projectile was fired. The system (2) is particularly suited for tracking a bullet fired by a sniper and identifying the location of the sniper. A telescope focuses infrared light from a relatively large field of view on to an infrared focal plane array (20). In a detection mode, the system (2) searches for the infrared signature of the projectile. The telescope's (18) field of view is steered in the azimuth by a step and stare mirror (8) which is driven by an azimuth drive motor (10) mounted on the frame. When a projectile is detected, the system (2) switches to a tracking mode and the mirror (8) is steered by the azimuth drive motor (10) and a pivot motor (14) to track the projectile. A laser radar system (24) provides a laser beam optically coaligned with the telescope axis.

Penetrating projectile for bomb disablement

Abstract: A specially designed projectile is disclosed which provides an initial cruciform-shaped slit or cut, followed by the creation of a round hole into a target. This controlled entry creates a very high localized pressure during initial impact to a target for a very short duration, followed by a longer sustained lower-impact pressure. This creates a fragment-free hole into the container and can allow the projectile to penetrate sensitive explosives inside the container without shock-initiating or igniting the explosives. The projectile can disable bomb circuitry itself or provide a controlled entry hole to allow low-pressure water or other projectiles incapable of penetrating the steel container to enter freely. The leading end of the projectile can, with a high degree of accuracy, sever wires, destroy batteries, capacitors, and other components within a bomb or select military ordnance. The projectile can be used alone or in tandem with water or other disablement projectiles.

On the design of a coilgun as a rapid-fire grenade launcher

Abstract: Two electromagnetic grenade launcher designs for armored vehicles are described. Both are based on the specifications for a conventional launcher, the Mark 19, which uses an M430 projectile. The first launcher has a muzzle velocity of 241 m/sec, as does the conventional one. For the second, the muzzle velocity was increased to 700 m/sec. Because of the large difference between the two velocities, the two designs had to be based on different energy considerations. The effects of variations of barrel parameters such as the pole pitch, the number of sections, and the thickness of the coils, are examined. For the projectile, the sleeve length parameter is varied. General guidelines are presented for the design of grenade coilguns.

Projectile with expanding members

Abstract: A projectile attachment is disclosed that has open-biased arm members that can be either mounted directly onto the projectile base or may be mounted to a mutual connection means which is then attached to the projectile base. The arms are compressed into a restrained position so that they may be inserted into the casing of the bullet. Upon firing, the arms extend to the unrestrained position. Upon impact the projectile penetrates the target then the extended arm members engage the target surface to cause widespread damage while slowing the projectile. The members may optionally have hook-like ends.

Device for storing projectile balls and for feeding them to the projectile chamber of a hand weapon

Abstract: A device for storing projectile balls and for feeding them to the projectile chamber of a hand weapon (1), with a ball container (3), with a conveying tube (2) which is connected at one end to the latter and the other end of which leads to the weapon (1), and with a conveyor for conveying a continuous row of balls out of the ball container (3) into the conveying tube, wherein the conveying tube (2) is designed as a flexible long conveying hose and the ball container (3) is provided with a carrying fixture (12) independent of the weapon.

Neutralization of hyperthermal multiply charged ions at surfaces: Comparison between the extended dynamical overbarrier model and experiment

Abstract: Within a semiclassical model, we investigate the dynamic neutralization and relaxation of slow (E kin 100 eV) multiply charged ions which are reflected on metal surfaces. Special emphasis is devoted to nearsurface interaction mechanisms. Our model includes a Monte Carlo sampling over projectile parameters and detailed ionic structure calculations of projectile energy levels. In a full trajectory simulation, our results simultaneously comply with measured trends in projectile kinetic energy gains and finalcharge-state distributions of the reflected ions as well as total electron yields and spectra. Recently discovered characteristic features in the electron spectra can be uniquely assigned to distinct above-surface regions of the projectile trajectory. S1050-2947 99 03009-7