Showing papers on "Projectile published in 1981"

Plasma dynamics of an arc‐driven, electromagnetic, projectile accelerator

Abstract: A model is analyzed to study the electromagnetic acceleration of projectiles using a device known as the rail gun. Current is conducted between the rails by a plasma arc which drives the projectile. The analysis includes determining the electromagnetic fields within the gun and solving the fluid‐mechanical equations of the plasma under the assumption that the flow parameters are steady in a frame that accelerates with the arc. Specifically, a set of coupled equations is derived which, when solved, yields the properties of the arc and the acceleration of the projectile. A limiting‐case analytic solution to the equations is found, and an iterative technique is employed to solve the equations numerically in the more general case. The results of the calculation are applied to analyze the arc in an experiment recently carried out by Rashleigh and Marshall. Some approximate scaling relations, which indicate how the properties of the arc vary with the dimensions of the rail gun, the mass of the projectile, the mass of the arc, and the accelerating current, are then derived. The results of the calculation are compared with those of others and some suggestions for future investigations are given.

Solid dose ballistic projectile

Abstract: A solid dose ballistic projectile formed entirely of a cohesive mixture comprising biologically active material, in the form of grindable solid particles having an average diameter between about 7 and 25 micrometers, and biologically inert binder, and capable of withstanding the stresses imparted thereon when the projectile is propelled ballistically from a barrel and implanted in the flesh of a living animal.

Electronic screening in heavy-ion--atom collisions

Abstract: A model is developed to describe the effects of screening by projectile electrons in heavy-ion--atom collisions. The effective nuclear charge of the projectile is estimated as a function of the interaction distance based on the spatial distribution of bound electrons derived from their electronic wave functions. Correlation of the effective interaction distance with collisional energy transfer through the Massey criterion enables comparison of model predictions of effective projectile charge with results obtained from differential-ionization-cross-section measurements. The model is found to provide a reliable estimate of screening for measurements involving fast helium and oxygen ions.

Quasifree-electron bremsstrahlung induced by the projectile field

Abstract: Continuum x rays from targets of Be, C, and Al bombarded with 6--40-MeV protons were observed with a Si (Li) detector. In addition to the secondary-electron bremsstrahlung (SEB), the spectra show another component, of which the high-energy limit is given by the relative kinetic energy between the projectile and orbital electrons of the target atom and by the Doppler effect. The component can well be explained in terms of the bremsstrahlung produced by the quasifree scattering of orbital electrons in the field of the projectile. The effect of the binding energy of the orbital electrons on this bremsstrahlung spectrum has been studied. From the comparison of the experimental results with theoretical predictions based on the plane-wave Born approximation and the binary-encounter approximation, the importance of the effect of secondary-electron escape from the target material on the SEB at high-projectile energies was pointed out.

Small weapons simulator

Abstract: A small weapons simulator in which a plurality of functioning and control modules are supported by a gun body having an exterior configuration to simulate a real weapon. The functioning modules include a laser beam transmitter to synthesize the trajectory of a bullet, recoil simulating means, sound simulating means and means to develop a lifting force on the forward portion of the gun body upon trigger actuation of the trigger, the recoil means and the sound simulating means to synthesize the characteristic of muzzle-rise on discharging a projectile from a weapon.

Design Manual for Impact Damage Tolerant Aircraft Structure

Abstract: : The Manual presents a methodology for integrating projectile impact damage tolerance into aircraft structural design. The information is presented in three sections: (1) Description of Projectile Threats; (2) Analysis Methods for Predicting Structural Response to Projectile Impact; and (3) Design Guidelines for Impact Tolerance. This report has been prepared at the request of the Structures and Materials Panel of AGARD.

Instability of controlled projectiles in ascending or descending flight

Abstract: Lloyd and Brown have shown that constant horizontal and vertical side forces and moments applied to a spinning projectile can result in dynamic instability. This instability arises from the nonlinear terms in the fixedplane coordinate system spin that appear in the equations of motion. By the use of the fixed-plane system (rather than Lloyd and Brown's nonrolling system) simpler relations can be developed, the full effects of gravity, drag and roll damping obtained, and the limitation to large gyroscopic stability factors removed. Very simple stability bounds are given for spinning finned missiles with spin rates well above resonance as well as for a gyroscopically stable shell. Exact solutions are given for finned missiles with zero spin but the motion of slowly spinning missiles should be numerically computed.

The production of continuous electron spectra in collisions of heavy ions and atoms. II. Direct coupling with the continuum

Abstract: For pt.I see ibid., vol.14, p.513 (1981). The continuum electron spectra produced in Nen+-Ne (n=1, 2, 3, 4) collisions have been measured as functions of the angle and energy of the ejected electrons. Electrons were measured in the energy interval between 16 and 1100 eV. Projectile energies from 25 to 800 keV, projectile charge states from 1+ to 4+ and emission angles between 45 and 135 degrees have been used. Spectra for Krn+-Kr (n=2, 3, 4, 5) were measured under the same conditions. For the Kr-Kr system only the exponential part of the spectrum was studied. For the Ne-Ne system the spectra have a pureexponential shape as a function of the electron energy. The cross sections decrease when the projectile charge is increased. The angular distributions are strongly anisotropic in the laboratory system but become almost isotropic in the centre-of-mass frame. It is found that the data can be described by a simple empirical relation. The authors' result indicate that radial and rotational couplings between highly promoted molecular orbitals and the continuum may be important.

A method for combatting of targets and projectile or missile for carrying out the method

Abstract: The invention relates to combatting of hostile targets (M) by firing of controllable explosive projectiles or missiles (P, PO) towards the target, which projectiles or missiles are provided with target tracking devices for automatic guidance of the projectile or missile by reception and detection of electromagnetic radiation originating from the target. In order to improve the accuracy of fire at least one projectile or missile fired in a burst is provided with transmitter means (T, A1) which are activated after detection of a target (M) for transmission of a signal indicating the position of the target relative to the projectile to following projectiles in the burst. In these following projectiles (P) a correction of the projectile trajectory in direction to a trajectory passing through the target is effected by means of the position indicating signal from the preceeding projectile (PO). Suitably all projectiles in a burst can be provided with such transmitter means (T, A1). Hereby each projectile in the burst will get a more correct trajectory towards the target as compared the closest foregoing projectile and reliable hit will be ensured after a relatively small number of projectiles. The target tracking device may be of any known type, as devices of radiometric type, radar or IR-type, electro-optical tracking device operating with visible light or laser light (Figure 1a).

Sabot and projectile

Abstract: A discarding sabot projectile for shotgun of unique construction whereby the separation of the projectile and sabot is enhanced by opposing air pressure and the unique construction of the sabot The sabot as utilized herein comprises a plastic body firmly encompassing, but not completely encapsulating a subcaliber projectile The plastic body includes a plurality of longitudinally extending slots forming symmetrical segments and further, segment having longitudinally extending grooves for reducing friction between the barrel bore and the sabot The segments are further defined at the other end thereof by longitudinal tapered edges The sabot, upon exiting the launching device begins to separate from the enclosed projectile beginning at the uppermost front end of the sabot as a result of air pressure flowing in the opposite direction of the sabot The longitudinal segment radially separates and will spread outwardly and as a result, the segments act as an air brake reducing the forward speed of the speed of the sabot This results in the separation of the sabot and projectile The separation is such that it does not interfere with the trajectory and the velocity of the subcaliber projectile, hence, resulting in a longer and more accurate trajectory

Particle emission at a /sup 20/Ne projectile velocity comparable to the Fermi velocity

Abstract: Inclusive energy spectra of the H and He isotopes emitted in the reactions of 860 MeV /sup 20/Ne with Ni, Ag, and Ta provide evidence that a statistically dominated projectile fragmentation mechanism entirely analogous to that observed at relativistic energies occurs when the projectile velocity becomes comparable to the Fermi velocity in the projectile. Additional particle emission not characteristic of either a fragmentation or compound nucleus source is observed.

Anti-materiel projectile

Abstract: An anti-material projectile which fragments wholly or in part due to impact shock on hitting a target thereafter penetrating the target causing damage. The projectile is preferably high density frangibile alloy having a ratio of compressive to tensile strength of 20 to 1. The projectile is useful against soft targets such as aircraft as well as armor targets where initial impact is at the armor plating. The projectile may be a composite of pyrophoric tip (41 c) with a projectile body (41a) of frangible alloy and an armor piercing alloy base (41b).

Electromagnetic projectile launching system with a concentric rail geometry

Abstract: An electromagnetic projectile launching system utilizes two cylindrical rail configurations. In one configuration, multiple conductive armatures are electromagnetically accelerated along rails which are located on the inner surface of a cylindrical barrel. The second configuration utilizes armatures located between concentric cylindrical rails. Rifling provides for spin stabilization of the projectile.

Muzzle arc suppressor for electromagnetic projectile launcher

Abstract: An electromagnetic projectile launcher having a pair of conductive rails with a breech and a nozzle end and an impedance electrically connected across the conductive rails adjacent the muzzle end of the conductive rails, and a second impedance which increases as the distance to the muzzle decreases, is disposed in the muzzle end of the rails and in arcs confined within the muzzle to commutate the current to the first impedance to substantially suppress any external arc as the projectile exits from the launcher.

Wobble nose control for projectiles

Abstract: An articulated nose is locked in axial alignment with the longitudinal axis of a rolling projectile body Pyrotechnic means within the nose is actuated to unlock the nose and tilt it toward the target when the error between the projectile path and the path to the target exceeds a predetermined threshold

Armor-piercing projectile

Abstract: An improved armor-piercing inertial penetrator projectile having a prepenetrator which has a substantially uniform flight diameter D, over substantially its entire length. A prepenetrator assembly is formed by a plurality of elements which are adapted to interact with the material of the corresponding target upon inpact so as to form an effective surface which has a diameter larger by a predetermined amount than the flight diameter D of the prepenetrator.

Explosive, particularly anti-aircraft, projectile, comprising a rotary directional-effect charge

Abstract: The present invention relates to an explosive, particularly anti-aircraft, projectile, comprising a rotary directional-effect charge having a main explosive charge projecting focusable damaging means, and a proximity fuse given a capability for azimuthal discrimination of a target. This projectile is characterised in that the focusable damaging means are mounted in rotation about the fixed main explosive charge in order to create a rotary axis of focused effects, and in that it comprises means for detecting coincidence of the rotary axis of focused effects with the direction of the target, for firing of the charge. For example, the focusable damaging means consist of a rotor comprising an annular fragmentation body 12 surrounding an annular explosive filling 13a, one sector 13 of which is provided with a group of preshaped or predefined fragments, means 14, 15 for priming the annular explosive filling of the main explosive charge 2, and several peripheral longitudinal explosive strips 161 to 168 for ejecting metal bars 171 to 178 for setting the rotor into rotation.

Muzzle arc suppressor for electromagnetic projectile launcher

Abstract: An electromagnetic projectile launcher having a pair of conductive rails with a breech and a muzzle end and an impedance electrically connected across the conductive rails adjacent the muzzle end of the conductive rails, and a second impedance in the muzzle end of the rails whereby arcs which commutate the current to the first impedance are confined within the muzzle to substantially suppress any external arc as the projectile exits from the launcher.

Finite compressibility in shaped charge jet and long rod penetration—the effect of shocks

Abstract: The classical theory of high speed jet and long rod penetration assumes incompressibility of both projectile and target. We extend here previous analyses of the implications of finite compressibility by including the effect of stationary shocks. For uniform projectile velocities V≲6×103 ms−1, depending on the type of target material, the total effect of compressibility is in the order of 10% or less, and is well approximated by the volume compressison work considered in the previous analyses [A. Coombs, private communication, Royal Air Force Research and Development Establishment, 1978; B. S. Haugstad, J. Appl. Phys. 52, 1243 (1981)]. At higher velocities shocks play an increasingly dominant role, contributing at least equally to the total compressibility effect at V≲104 ms−1. At these velocities there is a reduction in penetration depth of 10–20% in targets of aluminium or lead, while for plexiglass a full 35% reduction is predicted. Targets of lead or plexiglass experience local melting or even sublimation during penetration. In targets of aluminium, steel, platinum, and probably also in most other metallic targets, melting or sublimation first occurs well above typical projectile velocities.

Mechanics of high speed impact at normal incidence between plasticine long rods and plates

Abstract: A brief literature review of long rod impact is given. Experimental results and observations on the penetration and perforation of plasticine targets of finite thickness (25 and 50 mm) impinged upon normally by long rods of plasticine of various length-to-diameter ratios (2–12) are presented and discussed. An account of the range of modes of deformation as it pertains to long rods and targets of identical materials is given, i.e. mushrooming of the projectile leading-end, partial penetration and embedment of the projectile in the target, gross target penetration by the projectile, and penetration followed by perforation. The difference in penetration behaviour as between long and short rods is discussed. Plasticine has been used for both the target and projectile materials in order to simulate hypervelocity impact conditions for deformable long rod projectiles on deformable target plates. This permits the use of equipment based on an industrial stud driver which is substantially cheaper than the equipment (e.g. a light gas gun) required to achieve the range of speeds necessary for hypervelocity conditions with real ballistics-related metals and alloys. Projectile-target interactions and damage observed in the present tests compare well with those reported in similar investigations using metallic projectiles and targets. The attraction of performing ballistics experiments with plasticine models outweighs such inherent limitations as the inability to model the extreme conditions of temperature and strain-hardening in real materials, because testing is cheap and easily performed in a laboratory.

Compressibility effects in shaped charge jet penetration

Abstract: Among other hypotheses, the classical theory of high‐speed penetration assumes the incompressibility of both the projectile and target. Employing a simple Murnaghan equation of state, we show here that direct compressibility effects (pv‐work) on penetration depth are at most on the order of 10–15% for projectile speeds as high as 104 ms−1. Our results agree closely with similar results by Coombs (private communication, Royal Air Force Research Establishment, 1978), who used a more complex five‐parameter equation of state. This indicates that rather simple equations of state may adequately represent essential thermodynamic features of high‐speed penetration phenomena. The equation of state employed here furthermore allows approximate analytical results to be derived for both small and large projectile velocities.

Microwave-type projectile communication apparatus for guns

Abstract: Microwave projectile communication apparatus comprises a microwave probe fixed to a gun barrel at its muzzle end. A microwave oscillator, having a reference frequency selected for exciting the single fundamental electromagnetic mode in the barrel, is connected to the probe, for example, through a hybrid mixer configured for extracting, from moving projectile-reflected microwaves, a true Doppler signal for projectile velocity measurements. Connected between the oscillator and the probe is a signal modulator for modulating the reference oscillator signal to the probe. Connected to the signal modulator is a driver signal generator which controls the modulator in a manner enabling information, such as fuse delay time or target range, to be communicated to the projectile fuse. A conventional fire control computer may be used to provide to the modulator the data to be transmitted to the projectile. The barrel muzzle end may be internally shaped to function more effectively as a microwave antenna to enhance communication with projectiles after they have left the barrel. Corresponding methods for microwave communication with fired projectiles are provided.

Target apparatus for weapon fire training

Abstract: Target apparatus for use in the training of weapon direct fire, including a structure (1) in which a weapon can be placed and which forms a screen (3) of concave truncated spherical shape, at least one target image projector (4 ) located within the structure (1) for projecting a target image (T) onto the screen (3), with the projector (4) being mounted for universal movement so as to be capable of moving the projected target image (T) over the screen (3), and a visible laser projector (8) located on or adjacent the weapon to produce a visual indication (P) on the screen (3) by a projected beam of visible light, of at least a final portion of the flight path of the simulated fired projectile or missile, corresponding to the position at which the weapon was aimed when fired, for a projectile or missile whose trajectory or flight path cannot be controllably varied after firing, or corresponding to the position at which the weapon was aimed when fired and as subsequently controllably varied, for a projectile or missile whose trajectory or flight path can be controllably varied after firing. The target image projector (4) is located in the structure at the center of curvature of the concave truncated spherical shaped screen (3). An infra-red projector (9) may be included to project a beam of radiation along the line of sight of the weapon together with a detector (10) for this beam. The projector (8) may be operable to indicate visually on the screen (3) the impact of a missile or sequence of projectiles on the target image (T) and/or the whole of the flight path of the missile or projectile.

Steerable artillery projectile

Abstract: A steerable artillery projectile utilizing electro-optical circuitry to home on a laser designated target where the rear end of the projectile is displaceably coupled to the front end thereof which contains the electro-optical circuitry and munitions is disclosed. The displaceably coupled rear end of the projectile has a plurality of compartments equispaced around its longitudinal axis and each compartment has a gas cartridge which can be activated by the electro-optical circuitry. In flight, a selected gas cartridge may be discharged by the electro-optical circuitry causing the longitudinal axis of the rear end of the projectile to momentarily move out of line with the longitudinal axis of the front end of the projectile resulting in a modification of the flight path of the projectile to home on the laser designated target.

Navier-Stokes computations for conventional and hollow projectile shapes at transonic velocities

Abstract: : Advanced numerical techniques for the prediction of projectile aerodynamics have been applied to standard and hollow projectile shapes. Computer codes developed for solving the time dependent Generalized Axisymmetric and 3-D Thin-Layer Navier-Stokes equations have enabled simultaneous solutions of the inviscid and viscous regions of the flow field. Transonic computations have been performed for a 6-caliber secant-ogive-cylinder-boattail projectile shape at various free stream Mach numbers. Results have been obtained showing the formation of shocks near the nose-cylinder and cylinder-boattail junctions as well as the movement of these shocks with varying free stream conditions. Surface pressure distributions and velocity profiles have been obtained and are compared with available experimental data for angle of attack, alpha = O. Additional results are shown for alpha = 2 degrees, Mach = 0.96. The General geometry capability of the present method enables computations to be performed for many unique shapes such as hollow projectiles or ring airfoils. Internal and external pressure distributions are presented for a ring airfoil shape from Mach = 0.70 through Mach = 0.90.

Projectile carrier for liquid propellant gun

Abstract: This invention concerns an improved round for use in liquid propellant gu The improved round comprises a projectile attached to a carrier which is shaped like an abbreviated cartridge case. The carrier has a plurality of injection ports that communicate to an expandable volume. Sealing means prevent the escape of liquid propellant from the expandable volume which upon injection causes the projectile to be pumped to a forcing cone leaving the carrier behind. Several ignition means are used employing Boxer, Berdan or electric primers.