Showing papers on "Projectile published in 1988"

Ram accelerator - A new chemical method for accelerating projectilesto ultrahigh velocities

Abstract: A new method for accelerating projectiles from velocities of ~0.7 km/s up to -12 km/s using chemical energy is presented in this paper. The concept, called the "ram accelerator," is based on gasdynamic principles similar to those of an airbreathing ramjet but operates in a different manner. The projectile, which resembles the center body of a ramjet, travels through a tube filled with a premixed gaseous fuel and oxidizer mixture. The tube becomes the outer cowling of the ramjet, and the energy release process travels with the projectile. By tailoring the propellant mixture along the tube, a nearly constant acceleration can be achieved. In principle, the ram accelerator can be scaled for projectile masses ranging from grams to hundreds of kilograms and is capable of ballistic efficiencies as high as 30%. A straightforwar d, quasisteady, one-dimensional approach is used to model the acceleration process. The experimental facility developed to investigate the concept is described, and the results of recent experiments are presented. The velocity range of 690-1500 m/s has been explored in a 4.88-m long, 38-mm bore accelerator tube. Using methane, oxygen, and various diluents, accelerations of up to 16,000 g have been achieved with 75 gm projectiles and gas fill pressures of 20 atm. Proof of concept has been demonstrated, and agreement between theory and experiment has been found to be very good.

The Wound Profile: Illustration of the Missile-tissue Interaction

Abstract: The wound profile was developed at the Letterman Army Institute of Research in order to measure the amount, type, and location of tissue disruption produced by a given projectile, and to present the data in a standardized, easy to understand picture. The entire missile path is captured in one or more 25 X 25 X 50 cm blocks of 10% ordnance gelatin at 4 degrees C. The penetration depth, projectile deformation and fragmentation pattern, yaw, and temporary cavity of the missile in living anesthetized swine muscle are reproduced by this gelatin. Measurements are taken from cut sections of the blocks after mapping of the fragmentation pattern with biplanar X-rays. These data are then reproduced on a life-sized wound profile which includes a scale to facilitate measurement of tissue disruption dimensions, a drawing of the loaded cartridge case before firing, the bullet weight and morphology before and after firing (and calculated percent of fragmentation), and the striking velocity. This technique allows us to determine the wounding character of the projectile without the need for elaborate and expensive high-speed cine and X-ray equipment, or the need for shooting live animals. The method improves our understanding of the wounding process and should lay the groundwork to assure more rational and effective treatment.

Experimental archery: projectile velocities and comparison of bow performances

Abstract: Experimental study with replica bows and projectiles of a variety of types indicates the superiority of archery over the throwing of spears, and makes it possible to indicate a hierarchy of increasing efficiency in the main classes of bows.

Target scoring and display system

Abstract: An automatic target shooting system for determining projectile location relative to a target, calculating a score based upon the location and displaying a replica of the target with an indication of the location of the projectile relative to the target and the score. A target support structure defines a target area with criss-crossing X-Y-type coordinate light beams extending thereacross between light emitter devices and light receiving devices which generate output signals indicative of the location of a projectile during passage through the target area. The output signals are utilized by a computer device to identify the location of the projectile relative to the target and score the shot in accordance with the location. A replica of the target is displayed on a CRT screen with an indication of the location of the shot thereon and the score for the shot.

Target illuminating aiming system

Abstract: A target illuminating aiming system, for use with a firing weapon in reduced lighting, is provided with a light assembly for generating light and a light focusing assembly for directing the light generated by the light assembly at a target area into a first zone and a second zone. The second zone generally overlies the first zone and provides sufficient illumination of the target area such that an individual firing the weapon is better able to identify the target area. The first zone is alignable with the trajectory of a projectile fired form the weapon such that the projectile impacts in or near that portion of the target defined by the first zone.

Non-penetrating projectile and means therefor

Abstract: A projectile is described, which changes its shape upon impact on a target and thereby reduces the danger of penetration into a living target. The projectile is useful for the identification of individuals in crowds, by filling it with staining material which stains the target upon impact, and may further contain other liquid or gaseous materials, such as tear gas. The projectile of the invention is further useful for different uses, such as for gunfight simulation.

Self-contained supplemental guidance module for projectile weapons

Abstract: A self-contained supplemental guidance module for use with projectile weapons having a connected body and payload in attachable to the weapon between the body and payload, and includes self-contained power supply, inertial sensors and a plurality of incremental charges angularly spaced around an outer periphery of the module. A control processor in the module is operable responsive to the position of the module as detected by the sensors to calculate deviation of the projectile from a nominal flight path, taking gravity into account, and to detonate individual incremental charges when deviation exceeds a threshold and the incremental charge is in position to reduce the deviation. The supplemental guidance module is particularly applicable to barrage rockets, and includes a multi-level safe-and-arm apparatus initiating operation with sufficient axial thrust and disabling operation in the event of loss of sensor signals.

Critical energy criterion for the shock initiation of explosives by projectile impact

Abstract: The critical energy (Ec) criterion developed by Walker and Wasley for predicting the response of bare, heterogeneous explosives to flying-plate impact, is modified for application to flat-nosed rods and spherical projectiles. This modification redefines the shock duration term used in calculating Ec and implies that a minimum volume of explosive at a given shock energy is needed before initiation occurs. The modification also changes the L/D ratio of the projectile at which plate behaviour changes to rod behaviour from the currently accepted value of approximately 1/4 to 1/12. Comparisons between the modified criterion and published experimental data show that the same value of Ec can now be obtained from both flying-plate and more complex projectile impacts into the same explosive.

Combustion augmented plasma gun

Abstract: Apparatus for providing a controlled increase in muzzle velocity of a projectile while reducing peak value of gas pressure inside a gun barrel. A cartridge includes an elongated body having a central bore divided into three chambers, with a fuel chamber separated from an oxidizer chamber and an elongated capillary chamber by a plurality of membranes. A fuse wire and a power supply vaporize a plasma base in the capillary chamber and provide a controlled jet to provide combustion between a second fuel in the fuel chamber and an oxidizer material in the oxidizer chamber. The power supply controls the fuel-oxidizer combustion rate to obtain a relatively steady pressure of long duration against the projectile which results in high projectile velocity with relatively low peak values of pressure in the gun barrel.

Single and double ionization of helium by neutral-particle to fully stripped ion impact

Abstract: New measurements of direct single and double ionization of helium by hydrogen, helium, carbon, nitrogen, and oxygen ions are presented for projectile charge states ranging from 0 to 3+. These data are combined with previously published values to provide a detailed description of direct double ionization of helium for a wide range of experimental parameters, i.e., projectile ions include protons through oxygen, impact energies from 25 to 5000 keV/u, and projectile charge states ranging from neutral to fully stripped. The charge-state and impact-velocity dependencies of the measured cross sections are compared with the dependencies predicted by an independent electron multiple-ionization model. It is found that a multistep mechanism (i.e., the independent ionization of both target electrons) is the dominant direct double-ionization mechanism for charged-particle impact energies above 100 keV/u. This mechanism dominates until some maximum impact velocity, which depends on the projectile charge, is reached. For higher velocities a single-step ionization mechanism becomes important. The limited neutral-particle impact data indicate that the single-step mechanism becomes dominant at much lower impact velocities and there is no evidence of the multistep mechanism in the neutral-particle impact energy range investigated.

Projectile intended to be fired by a fire-arm

Abstract: Projectile characterized by anchoring means between the external surface of the tail (3) and the corresponding internal surface of the envelope (7) and characterized in that the head (2) of the core (1) is connected to the tail by means of a shoulder (6) and, facing the tail, the envelope (7) presents a rear portion (12) having a thickness larger than that of the remainder of the envelope, said rear portion (12) being provided on the outside with undulations (13) in order to form circular grooves substantially perpendicular to the longitudinal axis of the projectile and a free space (14) being provided between the shoulder (6) and the corresponding portion of the envelope (7).

Statistics of sputtering

Abstract: The statistics of the emission of sputtered particles is investigated with the Monte Carlo program TRIM SP. The probability of sputtering N atoms with N ≧ 0 per single projectile is determined for a wide range of projectile target combinations (mass ratio), incident ion energies and angles. The distribution of the probability of sputtering N atoms can be reasonable well described by a negative binomial distribution.

System to correct the trajectory of a projectile

Abstract: A system for correcting the trajectory of a projectile so that it reaches a designated target. The system comprises an optical radar comprising a laser emitting in the infrared band that makes it possible, in association with a processing device, to follow the movements of the target and of the projectile at the same time. The pieces of information given by the processing device enable a computer to calculate corrections to be made to the trajectory of the projectile in a final stage so that it meets the target. By modifying the trajectory of a projectile, such as a self-propelled missile or a shell, launched towards a target, the projectile can be made to hit a moving target or pass by at a reasonable distance that is small enough for the explosion provoked by its charge to definitely destroy the target.

Expanded metal armor

Abstract: A method, apparatus and article of manufacture is disclosed for using stand-up expanded metal armor members for protecting vehicles or other objects from ballistic threats. One or more spaced expanded metal member has projectile engaging faces which present sharp edges and arcuate surfaces to the small point of the projectile. When the point of the projectile engages the faces of the expanded metal members, the projectile is progressively deflected or shattered causing the wide arcuate side surface of the projectile to stop the projectile, or to pass through some or all of the members and engage the protected object with less than lethal force.

Ionisation of helium by antiproton and proton impact

Abstract: Single-electron ionisation of helium atoms by impact of antiprotons and protons is studied. The continuum-distorted-wave-eikonal-initial-state model is employed. Calculations of double differential cross sections, as a function of the final electron energy and for fixed electron-ejection angles, are given. A dip in the energetic region of electrons moving with low momentum with respect to the projectile is analysed. The importance of describing the dynamics of the electron in the simultaneous fields of the projectile and of the residual target is demonstrated.

Piezoelectric fuse for projectile with safe and arm mechanism

Abstract: A piezoelectric fuse, and safe and arm mechanism for a small active projectile is dislcosed including a piezoelectric element mounted within the projectile near the leading end thereof with an impact deformable electrically conductive shell spaced from and at least partially surrounding the piezoelectric element and a resilient material substantially filling the space between the piezoelectric element and the shell. Electrical leads connected the detonator to the shell and to a rearward piezoelectric element contact so that upon projectile impact, the shell deforms compressing the piezoelectric element generating a volatge thereacross, and thereafter, the shell makes electrical connection with a piezoelectric element forward contact actuating the detonator. The safe and arm mechanism includes an interrupter located in a "safe" position between the detonator and a lead charge. The interrupter may move from the safe position only upon both sufficient angular velocity and sufficient linear acceleration of the projectile.

Method and apparatus for launching a projectile at hypersonic velocity

Abstract: A projectile is accelerated to hypersonic velocity in an initially closed barrel of a diameter considerably larger than the projectile diameter which is filled with a compressed fuel-oxidizer mixture. The projectile comprises a conical nose portion, an intermediate portion formed to generate oblique detonation waves, and a tapering tail portion provided with several radial vanes. The projectile is propelled by an initiator gun at supersonic speed through one of the intitially closed ends in the barrel, were the detonation waves cause detonation and combustion of the fuel-oxidizer mixture. The detonation results in a high pressure increase to the rear of the projectile accelerating it along the barrel and shooting it at the reached hypersonic speed through the other, initially closed end of the barrel into the open.

Armature/projectile for a single or multi-turn rail gun

Abstract: A non-transitioning armature/projectile for launching from a single or multi-turn rail gun including: a nose; a tail; and a current carrying section between the nose and the tail including current channeling means for reducing the current concentration in the tail end of the armature/projectile and distributing the current toward the nose for generally balancing the electrically induced driving force with the inertial force and substantially reducing internal stress in the section.

Doppler radar method and apparatus for measuring a projectile muzzle velocity

Abstract: A muzzle velocity chronograph method and apparatus is described for measuring the velocity of a projectile (11) from a gun (13). In this method and apparatus a conventional radar Doppler signal from a radar device (15) is sampled and digitized by an analog-to-digital converter (23) and arranged in a succession of groups, each group representing a separate time period. A fast-Fourier transform is them computed for each group of samples by a signal processor (27) and peaks frequency measurements in the transformed data are tracked from one time period to the next. These peaks indicate the velocities of the projectile of interest and any other nearby moving objects. Finally, a least mean square error curve fit and standard regression algorithm are used to deduce the projectile's initial, muzzle velocity and the results displayed on a display (31). The method and apparatus provides accurate muzzle velocity determinaltions even in circumstances where the Doppler signal contains substantial interference caused, for example, by random noise and the presence of moving fragments in the direction of the projectile.

Guided artillery projectile with trajectory regulator

Abstract: A guided artillery projectile with a flight attitude or trajectory regulator in the autopilot of the projectile for the guidance of a transition into a gliding trajectory at the assumption of a predetermined pitch angle after the passage through the apogee of the ballistic firing trajectory.

Tracking and guidance techniques for semi-ballistic rounds

Abstract: A semiballistic projectile system is disclosed. The system includes a semiballistic projectile ground tracking and rangefinding system that selectively transmits course correction and rangefinding signals. The semiballistic projectile has a pyroelectric detector that includes a reflecting portion, nonreflecting portion, and a focusing lens for focusing electromagnetic signals onto the pyroelectric detector adjacent to its periphery. The reflecting port ion operates by reflecting impinging electromagnetic signals as return signals for orienting course corrections and the nonreflecting portion receives and decodes coded course correction signals for a jet thrust or other steering apparatus which corrects the projectile's course to a target.

Method and apparatus for initating stable operation of a ram accelerator

Abstract: A method and apparatus for supersonically accelerating a projectile in a thermally choked subsonic combustion mode. A projectile (50) is initially preaccelerated using either a tank (24) of compressed helium or a chemical propellant charge preaccelerator (152). The projectile enters a portion of a tube (22) filled with a combustible mixture (54) of a gaseous fuel and an oxidizer and is propelled by a ram acceleration process as the mixture burns. In several different embodiments, various devices are used to control the velocity of a shock wave generated as the projectile enters the combustible mixture and the dynamic impulse pressure immediately behind the projectile, so that the shock wave attaches to the projectile along an aft portion, thereby establishing a stable subsonic combustion zone along the aft end (64) of the projectile, in which combustion of the gaseous fuel accelerates the projectile down the bore of the tube. In one embodiment, a perforated sabot (52) is used to propel the projectile during preacceleration. The sabot has a plurality of passages (114) extending longitudinally between its front and rear surfaces, which are initially closed with a thin plate (110) during the preacceleration of the projectile. However, the plate is dislodged as the projectile enters the combustible mixture, allowing the dynamic pressure of the shock wave caused by the sabot to dissipate through the open passages.

Determination of very small projectile scattering angles by measuring recoil-ion transverse velocities

Abstract: A time-of-flight spectrometer (TOFS) is presented that enables differential cross section measurements at very small projectile scattering angles of θ ≤ 10−4 rad. The velocity perpendicular to the beam axis as well as the charge state of the recoiling target ion are determined simultaneously. The measured transverse velocity is shown to be a well defined function of the projectile scattering angle θ, even if the inelastic energy transfer due to electronic excitation is high. In first projectile scattering angle dependent investigations of multiple ionization processes, θ could be obtained with an accuracy of Δθ/θ Test measurements, properties and possible applications of the TOFS as we as limiting factors are discussed in detail.

Charge exchange at molecular-orbital pseudocrossings as an important mechanism for nonkinetic-electron emission in slow-multicharged-ion (v<v0) metal-surface scattering.

Abstract: Kinetic energy distributions of electrons emitted in the interaction of slow (10q-keV) multicharged ions (N,O,Ne,Ar) with metal surfaces (Cu,Au) are presented. We observe secondary-electron emission, quasielastic-scattering processes, and, superimposed upon this, one-center Auger decay of both projectile and target vacancies. Two classes of target Auger-decay features are observed. Long-lived target vacancies decay, leading to discrete Auger line features, similar to those arising from electron-impact excitation. Short-lived target vacancies appear to decay in the field of the projectile, leading to broadened Auger line features. Observation of the decay of target vacancies, and their correlation with the presence of particular projectile vacancies, shows that a measurable fraction of projectile vacancies survive until small-impact-parameter collisions with surface or subsurface atoms. The data imply that projectile neutralization proceeds via two channels, viz., capture of valence-band electrons to projectile excited states, followed by one-center Auger decay, and at pseudocrossings of molecular orbitals correlating with discrete inner-shell levels of the target and projectile.

Connection ring between a missile and a cartridge case

Abstract: The technical sector of the invention is that of connecting devices between a projectile and a case. The device according to the invention comprises a ring (6) which has a front part (8) connected to the projectile by a first fastening means and a rear part (7) fixed to the case (2) by a second fastening means. The device is characterised in that the second fastening means is shaped in such a way that the action of the pressure of the combustion gases of the propellant charge exerted on the projectile (1) causes the separation of the latter, carrying the ring, and of the case, and in that the rear part (7) then comes into contact with an inner surface of the chamber (4) so as to ensure gastightness. The invention is used for ammunition of the backswept type fired from a smooth barrel.

Spin stabilized carrier projectile equipped with a driving band

Abstract: The present invention relates to a spin-stabilized carrier projectile having a projectile base which is connected with a projectile body for carrying sub-ammunition projectiles, and a driving band arrangement connected respectively about the projectile base and about the projectile body for engaging the rifling of the gun barrel to impart spin respectively to the projectile base and the projectile body. The driving band arrangement includes a first partial driving band connected coaxially about the projectile base and a second partial driving band connected coaxially about the projectile body. This driving band arrangement reduces the spin forces transferred by the joint between the projectile base and the projectile body, thereby reducing the required joint strength. This in turn reduces the required ejection charge used to separate the projectile body and projectile base for release of sub-ammunition bodies contained in the carrier projectile.

Charge transfer in low energy atomic and molecular ion-surface scattering

Abstract: Charge transfer in low energy atomic and molecular ion-surface scattering is discussed within a general, time-dependent theoretical formalism, from which the origin of many observed phenomena such as neutralization, population of projectile excited states, alignment and polarization of light emitted by relaxation of such states, and coupling of projectile states to discrete target core states, is evident. Attention is focussed on time-resolved theoretical and experimental studies of the collision complex, designed to obtain a detailed understanding of the interaction. Both emission and adsorption spectroscopies, suitable for such time-dependent studies, are described. Possible trapping of a glancing incidence keV ion beam is reported, suggesting that glancing incidence surface scattering experiments, using both atomic and molecular projectiles, will in future provide important insights into the dynamics of chemical reactions and adsorption phenomena at surfaces. Finally, several of the outstanding theoretical and experimental challenges are reviewed.

Explosive projectile assembly with a projectile body

Abstract: An explosive missile or projectile assembly which possesses a projectile body and a ballistic hood which is positioned in front of the projectile body, wherein the hood encompasses a head end portion of the projectile body, and which includes an explosive charge arranged within the projectile body and a base detonator. An in-depth effect and fragmentation effect comes into bearing in the direction of firing, in that fragments are arranged intermediate the head end portion of the projectile body and the ballistic hood, and in which the projectile body is equipped with performed fragments.