Showing papers on "Projectile published in 1986"

Experiments with Spears and Arrows on Animal Targets

Abstract: Despite the considerable attention that archaeologists have given the formal and typological aspects of prehistoric projectile points, relatively little research has been done concerning their functional aspects. To better understand the effectiveness and penetrating characteristics of, and damage to, different projectile tips, an extensive experimental program was conducted. Both shaped and unmodified chert tips were hafted onto arrow- and spear-shafts and propelled into dead animals. The results led to recognition of differences in damage patterns, the importance of certain variables for projectile point longevity, and the penetration potential of specific kinds of projectile heads.

Projectile fragments isotopic separation: Application to the lise spectrometer at GANIL

Abstract: The isotopic separation of intermediate-energy (30 to 100 MeV per nucleon) heavy-ion projectile fragments is theoretically and experimentally investigated. Physical separation of nuclides is achieved through magnetic analysis (AZ sensitivity) and differential stopping-power effects (Z−2 sensitivity). Depending on the specific case, a complete mass and charge separation may be achieved or a few nuclides may be selected simultaneously. The projectile fragments isotopic separation method described allows us to obtain an experimental mass separation AΔA ≈ 100. Simple formulae are given to determine the optimum factors for the best separation and transmission of the device. First applications to the spectroscopy of exotic nuclei lead to the new observation of the beta decay of 37P at GANIL and 15B at CERN.

Projectile Point Size and Projectile Aerodynamics: An Exploratory Study

Abstract: Although often treated as complete cultural entities, projectile points are only the partial remnants of complex projectile delivery systems. The problem explored in this paper is the inferences th...

Method and apparatus for setting a projectile fuze during muzzle exit

Abstract: A method and apparatus for setting a time delay value in an electronic fuze of a projectile exiting the muzzle of a gun barrel, in which a single transmitter coil concentrically mounted to the gun muzzle is utilized both to sense the presence of the projectile at the gun muzzle and to inductively transmit a radio frequency signal having a duration proportional to the fuze time delay value to a receiver coil disposed on the projectile. The transmitter coil is energized from a radio frequency oscillator before the projectile is fired. As the front end of the projectile begins to emerge from the gun muzzle, its presence is detected by a change in the transmitter coil impedance, and the transmitter coil is automatically deenergized. The receiver coil is spaced from the front end of the projectile so that it is not inductively coupled to the transmitter coil, the transmitter coil is reenergized from the oscillator for a time period proportional to the fuze time delay value to be set, then again deenergized until the projectile has completely emerged from the gun muzzle. The signal received by the receiver coil is processed by circuitry within the projectile to set the fuze time delay value.

Summary of EM launcher experiments performed at LLNL

Abstract: Performance results for three railguns are summarized. The system used a helium gas-driven injector and railgun launcher to accelerate 1- and 4-g polycarbonate projectiles intact up to 6.6 and 3.0 km/s, respectively. A 625 kJ capacitor bank powered the railgun, and an adjustable inductor provided pulse shaping and peak current control. Operation in hard and soft vacuum was reliably achieved. Projectiles were accelerated without blowby of injector gas or plasma. The diagnostic system measured the projectile position and launch velocity, verified that the projectile was launched intact in the desired direction, and identified system components where improvements could enhance performance. Flash x-ray radiography measured velocity and verified that projectiles were intact. Post-launch projectile travel along the axis of the launcher without tilt was recorded with flash radiographs and impact impressions or holes in witness plates. The system performed as expected up to 4-5 km/s but below expectations at higher velocities. Our diagnostics suggest that the decreased performance was probably caused by the restriking of a second arc in the breech of the railgun, which shunted the current from the propulsive arc. Estimates of ablated launcher mass, drag forces, methods of eliminating restrike, and suggestions for improving the performance of railguns are discussed.

The reconnection gun

Abstract: An electromagnetic launcher called the reconnection gun is introduced. Its potential performance is shown to be superior to that of a modern railgun for projectiles with mass greater than a few hundred grams. It has a "characteristic velocity" which is an order of magnitude lower for much lower energy loss to ohmic heating. Also, it has several advantages for producing higher acceleration including; no barrel, no drop in acceleration with increase in projectile mass, higher peak pressure on the projectile and smaller differences between average and peak pressure. Experimental results and plans for high-performance, multi-stage designs are briefly discussed.

Plasma propulsion apparatus and method

Abstract: A projectile is accelerated in a barrel bore by applying a plasma jet to a projectile propelling fluid. The plasma jet is derived from a structure forming a capillary passage having a wall formed by a low molecular weight, dielectric powdery filler or water in many rigid containers, shaped as spheres or straw-like tubes having axes parallel to the passage longitudinal axis. The fluid and jet interact so the fluid is heated by the jet, whereby low atomic weight constituents of the fluid are sufficiently heated to become mixed with the plasma to form a high pressure mixture that is injected into the bore to accelerate the projectile. The fluid is dragged into the plasma during mixing to cool the plasma and form a boundary layer between the plasma and the barrel walls so that the mixture does not cause substantial damage to the walls of the bore. The plasma is energized by applying voltage from an electric pulse source to electrodes at opposite ends of the passage. The pulse has a wave shape and duration for initially igniting the plasma source and for thereafter applying energy to the ignited plasma to control the pressure of the mixture. Initially, the fluid cools the plasma without the mixture developing sufficient pressure to accelerate the projectile appreciably. The wave shape and duration are such that the pressure applied to the projectile remains substantially constant while the projectile is being accelerated through the barrel, as occurs during about one-half of the projectile travel time in the barrel.

Target scoring and display system and method

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 to 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.

Ballistic spall liner

Abstract: A lightweight, economical, add-on armor plate, ballistic spall liner, installable on the inner surfaces of unprotected vehicles, structures, or other craft. The spall liner provides additional protection to vehicle occupants and internal equipment from the risk of injury or damage due to flying metallic debris, "spall", caused by ballistic damage to the vehicles or the structure's interior when a munitions-type projectile penetrates a wall. The spall liner is a laminate made from layers of high tensile strength, woven fabric such as polyaramid fabric or ballistic nylon which are bonded together with at least one reinforcing layer of martensite sheet steel interposed between the woven fabric layers. The spall liner controls the spall generated by the penetration of a munitions-type projectile by dissipating the projectile's force, framentizing the projectile, and trapping the fragments in the spall liner's interior.

Ion-induced secondary electron spectra from clean metal surfaces

Abstract: Energy distribution curves of low-energy secondary electrons emitted from clean metal surfaces have been measured for high energy ion bombardment. The shape of the spectra was found to depend on the target material, the projectile species and for heavy ion impact also on the projectile energy.

Electronic stopping values for low velocity ions (9 ≤ Z1, ≤ 92) in carbon targets

Abstract: We have measured the specific energy loss, ΔE/ΔX, for 23 projectiles in carbon targets at low velocity, v < v0. We have used a Monte Carlo calculation to determine the elastic energy loss appropriate to the experimental conditions. The electronic stopping values derived from our measurements show a marked oscillation in Z1, the projectile atomic number, and depend on the target thickness. Our data are compared to other measurements in the same velocity regime.

Separate determination of concentration profiles for atoms with different masses by simultaneous measurement of scattered projectile and recoil energies

Abstract: When the energies of a scattered projectile and the recoiling target nucleus are measured both at the same time, the energy of the lightest particle can be used to select the mass while the energy of the heaviest particle is most sensitive to the depth from which both particles emerge. This is shown for α particles of 30 MeV scattered at 82° on 12C, 13C, 16O and 27Al and the corresponding recoils. The depth resolution of about 50 nm is comparable to that obtained in the measurement of recoil energies from the elastic scattering of heavy ions. The selectivity is almost perfect even between the carbon isotopes. Given suitable improvements, the sensitivity may reach the ppm region.

Fin-stabilized projectile

Abstract: A fin-stabilized projectile for weapons selectively possessing either a smooth, and in particular, a rifled weapon barrel, which possesses a discardable thrust ring constituted of segments arranged on the central form-fitted component, and of a through-sliding guide band, and which is provided at the tail end of the projectile with a multi-finned stabilizing guidance mechanism which is rotatable about the longitudinal axis of the projectile

Atomic collisions with relativistic heavy ions. VI. Radiative processes.

Abstract: Besides characteristic target and projectile x rays, x-ray continua and radiative-electron-capture photons are seen in collisions with relativistic heavy ions ranging in energy from 82 to 422 MeV/amu and in atomic number from Xe to U. The angular distribution, centroid energy, cross section, and line shape of the broad radiative-electron-capture lines are analyzed. The observed continua are due to primary- and secondary-electron bremsstrahlung. In the projectile frame, primary bremsstrahlung is the radiative scattering of incident target electrons from the projectile nucleus. The continuum cross sections and angular distributions are calculated, and are compared with experiment. Secondary-electron bremsstrahlung, due to the radiative scattering of ionized target electrons from other target nuclei, is target-thickness dependent, and the cross section increases roughly with the square of the target atomic number. The calculated primary-electron bremsstrahlung cross sections are lower than experiment.

Spin-stabilized projectile with pulse receiver and method of use

Abstract: A spin-stabilized projectile (20) the trajectory of which can be improved to increase accuracy with the projectile (20) being controlled by a source of electromagnetic radiation providing pulses carrying encoded information. The projectile (20) includes a nose end (22) and a midportion (26) having a periphery disposed about which are a plurality of spaced masses (28) with a high explosive charge (30) associated with each mass (28) for high explosive detonation acceleration of its corresponding mass (28) to provide an impulse to the projectile (20). A projectile (20) has a boatail (24) defining a cavity (32) opened at the rear end of the boatail (24). Received in the cavity (32) is a pulsed electromagnetic radiation receiver (36) and processor (44, 48). This radiation receiver (36) and processor (44, 48) has a component for determining the approximate elapsed time from firing of the projectile (20), a component for determining the direction of the source of electromagnetic radiation with respect to the projectile, a component for determining approximate vertical, a component for determining rotational rate, and a component for counting the times between adjacent electromagnetic pulses in a series of such pulses. The radiation receiver (36) and processor (44, 48) also includes a microprocessor (48) reponsive to these components for controlling selective high explosive detonation acceleration of the masses (28) to improve the trajectory of the projectile (20) towards its target. A method of controlling a number of such projectiles is also disclosed.

Critical second-order scattering in three-body rearrangement and break-up processes

Abstract: Critical-angle scattering arising from a sequence of two binary collisions of the type observed in electron capture is shown to occur more widely in three-body collisions. The occurrence of critical angles depends upon the masses of the three particles and their mutual relative momenta in the final state. Where the projectile and one target particle have small relative momentum after the collision (as in capture to the continuum) a condition is derived in which real capture occurs as a limiting case. It is suggested that critical-angle scattering will lead to observable structure in the distribution of electrons emerging with low momentum relative to fast incident ions, positrons or electrons. In ionisation processes where the ionised electron does not have low momentum with respect to the projectile, different second-order terms lead to critical scattering whenever the ionised electron occupies the 'binary ridge' with respect to the outgoing projectile.

Projectile with an extendable boattail

Abstract: A projectile having a streamline assembly which includes a frusto-conical saddle secured to the boattail area of the projectile bullet, a carrying cylinder having one end secured to the saddle, with multiple, concentrically oriented, tapered, collapsible rings normally located inside the opposite end of the carrying cylinder and biased against a pressure disk fitted against the opposite end of the carrying cylinder, wherein firing of the projectile causes the pressure disk to tear away from the carrying cylinder and deploy the collapsible rings outwardly of the carrying cylinder and behind the bullet in a "beehive" configuration, to reduce air resistance as the projectile moves through the atmosphere. In a preferred embodiment the pressure disk is pressed against the carrying cylinder by means of a brass screw, the threads of which engage an aperture in the saddle and are stripped from the brass screw to release the disk when the projectile is fired.

Apparatus and method for the acceleration of projectiles to hypervelocities

Abstract: A projectile is initially accelerated to a supersonic velocity and then injected into a launch tube filled with a gaseous propellant. The projectile outer surface and launch tube inner surface form a ramjet having a diffuser, a combustion chamber and a nozzle. A catalytic coated flame holder projecting from the projectile ignites the gaseous propellant in the combustion chamber thereby accelerating the projectile in a subsonic combustion mode zone. The projectile then enters an overdriven detonation wave launch tube zone wherein further projectile acceleration is achieved by a formed, controlled overdriven detonation wave capable of igniting the gaseous propellant in the combustion chamber. Ultrahigh velocity projectile accelerations are achieved in a launch tube layered detonation zone having an inner sleeve filled with hydrogen gas. An explosive, which is disposed in the annular zone between the inner sleeve and the launch tube, explodes responsive to an impinging shock wave emanating from the diffuser of the accelerating projectile thereby forcing the inner sleeve inward and imparting an acceleration to the projectile. For applications wherein solid or liquid high explosives are employed, the explosion thereof forces the inner sleeve inward, forming a throat behind the projectile. This throat chokes flow behind, thereby imparting an acceleration to the projectile.

MeV heavy ion induced desorption from insulating films as function of projectile velocity

Abstract: Fast heavy ions beams from accelerators at Darmstadt and Orsay have been used to study secondary ion emission from surfaces of mineral and organic solids over a large projectile energy range. The projectile velocity dependence of the secondary ion yield shows a rather universal behaviour and it is clear that there is no direct relationship between the electronic stopping power and the yield excitation functions. Comparisons of theoretical models with experimental results are presented in the last section.

Method of and apparatus for deriving a high pressure, high temperature plasma jet with a dielectric capillary

Abstract: A pulsed high pressure, supersonic plasma jet for accelerating a projectile through an elongated confined bore is derived from a dielectric structure including a capillary passage having an interior wall surface from which plasma forming material is ablated in response to a discharge voltage applied to first and second electrodes respectively forming a nozzle and plug at opposite ends of the passage. The nozzle injects the plasma into the bore behind the projectile.

Glass Fracture Mechanism—A Rethinking

Abstract: Conventional attitudes within the forensic science community concerning the fracturing of glass center around tensile failure of the glass, frequently depicted as a “bending” of the glass. While this is not conceptually incorrect, it represents only one case of a more universal phenomenon in which the tensile failure of glass does not necessarily involve any significant deflection of the glass. Tensile failure can be achieved with either quasi-static or dynamic loading of the glass. In quasi-static loading, tensile failure will initiate a fracture at the weakest point (that is, the locus of a Griffith crack), but the surfaces of this crack may be in optical contact, and thus no perceptible deformation of the glass would be required before failure. A consideration of dynamic loading is necessary to explain the “cratering” effect observed in moderate- to high-velocity projectile impact. In sharp dynamic loading (for example, a bullet impact) the tensile stress is provided by the reflection and subsequent interference of the compression waves which precede the passage of the projectile; this particular type of stress results in Hopkinson fractures, a multiplicity of which creates a crater. The dimensions and chamfering of projectile craters are a manifestation of the crack velocity propagation, and are not inherently a function of projectile velocity or caliber.

Wake stabilized supersonic combustion ram cannon

Abstract: A supersonic combustion ram cannon (1) includes a conical projectile (8) with a flat base (9) which produces a subsonic wake (12) as it flies through a barrel (2). The projectile is configured to avoid a normal shock, relying instead on supersonic compression, combustion and gas expansion. The supersonic combustion of a fuel-oxidizer mixture around the tail of the subsonic wake, pressurizes the wake and drives the projectile forward. By utilizing wake stabilized supersonic combustion, the compression and combustion pressures can be matched to the limiting barrel working pressure, thereby providing for optimum thrust and maximum projectile acceleration.

Apparatus for and method of accelerating a projectile through a capillary passage and projectile therefor

Abstract: A high pressure plasma initially formed from a fluidizable substance in a confined region of a passage behind a projectile in the passage initially accelerates the projectile toward an open end of the passage. The plasma in the confined region is ohmically heated to a higher pressure by a discharge current flowing longitudinally through the passage and the projectile.

Method and apparatus for accelerating a projectile through a capillary passage with injector electrode and cartridge for projectile therefor

Abstract: A high pressure plasma initially formed from a fluidizable substance in a confined region of a passage behind a projectile in the passage initially accelerates the projectile toward an open end of the passage. The plasma is intially derived by supplying a discharge current to an electrode in the substance. The plasma in the confined region is ohmically heated by an azimuthal current generated in the plasma by an AC magnetic field that is coaxial with the passage or by a discharge current flowing longitudinally through the passage and projectile. A cartridge includes the projectile and a wall of the passage that is evaporated after the projectile has been fired so the evaporant flows out of the passage after the projectile.

Electric generator assembly for a projectile

Abstract: A rotational brake member controls the rotational velocity of an electric generator assembly housed within a projectile. The assembly includes an air-driven turbine and an electric generator. The brake member is affixed to the turbine which drives a rotatable element of the generator to produce electric power. The brake member is formed from an elastically deformable material and is adapted to contact the stationary surface proximate the periphery of the brake member at a predetermined angular velocity. In addition, a shock absorbing member formed from an inelastically deformable material is positioned to absorb shock to the turbine when the projectile is fired. Preferably, the generator further includes an elastomeric seat for biasing the turbine away from the shock absorbing member after the projectile has been fired.

Method for homing a projectile onto a target and for determining the ballistic trajectory thereof as well as arrangements for implementing the method

Abstract: A method for homing a projectile onto a target wherein the projectile is self-steering in an extended trajectory in its flying end phase, in particular an artillery projectile, from which there is effected a search and homing onto a target. Also provided is an arrangement for the change of a projectile which is self-steering and program-controlled during its flight end phase and which is equipped with a target searching device, in particular an artillery projectile, which is equipped with control and steering arrangements and with control rudders for transition from a ballistic firing trajectory into an extended forward trajectory and then for homing into a target approach trajectory. An arrangement is also included for the input of the characteristics of a ballistic launch trajectory into the memory of a navigational computer on board of a projectile which is self-steering along an extended flight end phase.