Showing papers on "Projectile published in 1982"

Kinetic theory of particle stopping in a medium with internal motion

Abstract: Expression have been derived that relate the stopping power and energy-loss straggling in a medium with internal motion for penetrating charged particles to the corresponding quantities applying to the equivalent medium at rest These expressions have been based on a general binary-encounter picture and apply to nonrelativistic velocities and arbitrary mass ratios Convenient expansions have been found in the limits of very high and very low projectile velocity The results are applied to both nuclear and electronic stopping of charged particles The capability of the scheme is tested upon the degenerate free-electron gas, for which accurate expansions at high and low projectile speed are known, with regard to both stopping and straggling The scheme allows evaluation of shell corrections to stopping power and straggling of atomic and molecular gases beyond the range of validity of the leading terms in an expansion in inverse powers of electron velocity A seeming disparity between high-speed straggling parameters calculated for the Fermi gas on the one hand, and an atomic target on the other hand, is attributed to different ground-state properties of the two systems in zero order An essential difference is pointed out between the predictions of the dielectric theory and the present scheme with regard to the velocity dependence of energy-loss straggling in the low-speed limit

Bi-axial supporting arrangement which can withstand high acceleration forces

Abstract: The invention relates to a bi-axial support of a rotatable body in a projectile for supporting said body such that it can perform small tilting motions about two mutually perpendicular axes lying in a plane, which is perpendicular to the longitudinal axis of the projectile. The support consists of a spherical or partly spherical bearing body introduced into a correspondingly spherical cup-shaped recess in a projectile-fixed part having the open end directed forwards in the motion direction of the projectile. The spherical bearing body is retained in the recess by means of two pairs of link arms defining two virtual tilting axes for the bearing body and connected to two output shafts such that a tilting motion of the body about the respective virtual axis results in a rotation of the respective output shaft and vice versa. When firing the projectile the spherical surface of the bearing body comes in metallic contact with the spherical surface of the recess, whereby the support can withstand very high acceleration forces in any direction.

Charge state and slowing of fast ions in a plasma

Abstract: The charge state of a projectile ion traveling through a plasma target under conditions relevant to ion-beam fusion is calculated. It is found that, at the projectile energies and target parameters considered, the projectile ionization is significantly higher than that of the same projectile species in a cold target. The resulting strong effects on the range and on the shape of the energy deposition profile are shown in several examples of full dynamic calculations.

The effects of projectile geometry on the performance of ballistic fabrics.

Abstract: A ballistic laboratory was designed and built to accommodate the impact of . Kevlar® woven fabric of varying ply levels, while manipulating the geometrical shape, weight, and impact velocity of the projectile. A chronograph system was used to measure the striking and residual velocities of the missile.Empirical relations were determined between the experimental data and the quantity 1/√L, where L is the ogive length of the projectile. This quantity was found to be useful in characterizing projectile geometrical effects on the impact performance of woven fabric systems. The effects of projectile shape on the number of fabric plies, velocity loss data, and thus V50 values are characterized by the empirical relations.

Laboratory simulation of planetesimal collision

Abstract: Low-velocity impact experiment on rocks was performed to reveal a nature of collision process of planetesimals. Projectiles of mild steel (S15CK) and rocks (tuff and basalt) with velocities of 17 to 270 m/s were impacted against four kinds of rocks (tuff, basalt, granite, and dunite) with various shapes and sizes. Imparted energy divided by target mass Ei ranges 106 to 108 erg/g. The phenomena associated with the impact of mild steel against spherical targets were classified into five categories. The categories vary with increase in impact velocity as follows: (1) rebound of projectile with no contact damage on target, (2) rebound of projectile with fragmentary chips, and creations of a contact damage (crater?) and radiating fissures on target, (3) rebound of projectile with longitudinal splitting of target, (4) destruction of target with producing shatter conelike fragments, and (5) complete destruction of target. We cannot see any difference in the above categories between various kinds of rocks. The shape of the target also does not influence the categories significantly. The size distribution of the fragments produced by the complete destruction was well expressed by an inverse power law relation, n(l) dl ∝ l−α−1dl, where n(l) is the incremental number of the fragments within a linear increment dl, l is the size, and α is constant; α seems to increase with increase in Ei,. An empirical relationship between α and Ei was approximately given by α∝ log Ei. Empirical formulae for the maximum fragment mass normalized by the original target mass (Ml/Mt) and Ei were also presented for each rock type. It is found from the shape distribution of the fragments produced by the shatter cone type destruction that the length ratios between the shortest and the longest axes, c/a, and between the intermediate and the longest axes, b/a, were greater than 0.2 and 0.3, respectively. Average length ratio of a:b:c is roughly given by 2:√2:1. Collisional phenomena associated with low-velocity impact experiment were shown to be different from those observed in the high-velocity impact experiment. The difference in mechanical properties between projectile and target significantly influenced the collisional behavior. For collision between rocks with similar mechanical properties, relative size between projectile and target played an important role in determining the collisional mode: Only the smaller body was destroyed completely, and the larger body suffered no damage even if released Ei was enough to destroy both colliding bodies simultaneously. This observation suggests an important implication in the early stage of planetary formation, that runaway growth of the largest planetesimal takes place even when the collision condition prefers catastrophic destruction to other collision types.

Electromagnetic projectile acceleration utilizing distributed energy sources

Abstract: Circuit equations are derived for an electromagnetic projectile accelerator (railgun) powered by a large number of capacitive discharge circuits distributed along its length. The circuit equations are put into dimensionless form and the parameters governing the solutions derived. After specializing the equations to constant spacing between circuits, the case of lossless rails and negligible drag is analyzed to show that the electrical to kinetic energy transfer efficiency is equal to σ/2, where σ=2mS/Lq20 and m is the projectile mass, S the distance between discharge circuit, Lthe rail inductance per unit length, and q0 the charge on the first stage capacitor. For σ=2 complete transfer of electrical to kinetic energy is predicted while for σ>2 the projective‐discharge circuit system is unstable. Numerical solutions are presented for both lossless rails and for finite rail resistance. When rail resistance is included, >70% transfer is calculated for accelerators of arbitrary length. The problem of projecti...

Characteristics of Projectile Fragments Produced from Heavy-Ion Collisions at 2A GeV

Abstract: The interaction mean free paths in nuclear emulsion of relativistic projectile fragments, 3< or =Z< or =26 emitted from two heavy-ion beams of /sup 40/Ar and /sup 56/Fe at an energy of approx.2 GeV/nucleon have been measured and they gave evidence for anomalously short mean free paths in the first 2--3 cm after their production than at larger distances. Some characteristics of the primary and the secondary interactions connected with the anomaly are presented.

Proton-induced alignment of theL 3-subshell in heavy atoms

Abstract: The proton-induced alignment of theL-shell in heavy atoms (54≦Z≦92) has been studied by measuring the anisotropy of the emitted x radiation. The proton energies ranged from 150 keV to 10 MeV. The alignment in different target atoms was found to approximately follow a universal curve. Calculations in Born approximation as well as in the semiclassical approach give a good description of the observed alignment at high projectile velocities. In the low energy regime the deflection of the projectile in the Coulomb field of the target nucleus has to be taken into account to obtain agreement between theory and experiment.

Projectile proof vest

Abstract: A vest having projectile-stopping capabilities, including a network of inner shock-resistant plates lying under a layer of ballistic material to minimize the force imparted by a slowing projectile upon a wearer of the vest.

Fragmentation of ice by low velocity impact

Abstract: Low velocity impact experiments (014 to l km/s) carried out in polycrystalline water ice targets at 257 and 81 K resulted in interactions which can be assigned to four fragmentation classes, cratering, erosion, disruption, and total fragmentation Specific kinetic energies for the transitions between these classes range from l x 10^5 to 7 x 10^5 ergs/g for 81 K ice and from 3 x 10^5 to ~ 2 x 10^6 ergs/g for 257 K ice These values are about one to two orders of magnitude below those for silicate rocks The mass vs cumulative number distribution of fragments in our experiments can be described by a simple power law, similar to that observed in fragmented rocks in both the laboratory and in nature The logarithmic slopes of cumulative number vs fragment weight vary between - 09 and - 18 decreasing with increasing projectile energy and are approximately independent of target temperature The shapes of fragments resulting from erosion and disruption of ice targets are significantly less spherical for 257 K targets than for 81 K targets Fragment sphericity increases with increasing projectile energy at 257 K, but no similar trend is observed for 81 K ice Our results support the hypothesis that the specific projectile energy is a measure for target comminution for a relatively wide range of projectile energies and target masses We apply our results to the collisional interaction of icy planetary bodies and find that the complete destruction of a target body with radii between 50 m and 100 km· range from 10^(17) to 10^(27) ergs Energies corresponding to basaltic bodies of the same size range from 10^(18) to 10^(28) ergs Our experiments suggest that regolith components on icy planets resemble those on rocky planetary bodies in size and shape We predict that the initial shapes of icy particles in the Saturnian ring system were roughly spherical The initial mass distribution of ring particles should follow a power law with a slope of ~ - 15

Application of Ampere’s force law to railgun accelerators

Abstract: This paper examines the question of where in the railgun accelerator circuit is the seat of the recoil force. It is explained that conventional electromagnetic field theory and the older Ampere electrodynamics disagree on this point. The former places the recoil force in the remote gun breach while the latter claims it resides in the railheads close to the projectile. An experiment is described which tends to confirm the Ampere prediction. The second part of the paper deals with the force distribution along the projectile branch of the accelerator. Finite current‐element analysis has been employed to show that both theories give approximately the same acceleration force distribution and that the total acceleration force furnished by them agrees well with an experimental check. However, according to the Ampere law, the projectile branch of the circuit should also be subject to strut compression and not only to transverse acceleration. This aspect of the Ampere electrodynamics still awaits experimental confirmation.

Highly accurate projectile for use with small arms

Abstract: A highly accurate projectile for use with small arms especially pistols and revolvers, having a cylindrically-shaped body portion and a nose formed adjacent thereto. The cylindrically-shaped body has a length which is equal to at least half the overall length of the projectile in order to position the center of gravity of the projectile within the body portion. The nose of the projectile is in the nominal shape of a truncated cone having sides which are rounded at the forward end thereof in order to meet a flat front surface. The flat front surface locates the center of pressure of the projectile well forward of the center of gravity of the projectile. The unique configuration and distribution of weight of the projectile allows for its highly accurate use with small arms.

Flight Instabilities of Spinning Projectiles Having Nonrigid Payloads

Abstract: Severe flight instabilities were experienced by an Army spin-stabilized projectile which had a partialsolid/partial-liquid pay load. Characteristic of this flight instability was a sharp increase in projectile yaw angle accompanied by an abrupt loss in projectile spin rate. It was known that this instability was due to movement of the nonrigid payload, but the exact mechanism causing the effect was not understood. A special laboratory test fixture was used to force a full-scale projectile payload to simulate the combined spin and simple coning motion of the projectile in flight. The fixture was used to determine critical factors influencing the payload-induced despin moment, and from this the associated flight stability was inferred. Candidate payload configurations intended to eliminate the instability were evaluated on the fixture, culminating in a payload design which provided the desired functional and flight performance. Subsequent fixture tests with homogeneous, viscous liquid fills produced similar despin characteristics to those obtained with the partial-solid/partial-liquid payloads. The despin data indicated increasing instability with increasing liquid viscosity with a maximum effect at a kinematic viscosity of about 105 CS whereupon the instability decreases with increasing viscosity. Instrumented flight tests showed good correlation with fixture results. The similar instability characteristics of the homogeneous, viscous liquids and the partial-liquid/partial-solid payloads could aid in developing a general theory describing this instability.

Electromagnetic projectile launcher with combination plasma/conductor armature

Abstract: An electromagnetic projectile launcher includes a combination plasma/conductor armature structure which serves to conduct current between a pair of generally parallel conductor rails and to propel a projectile along the rails. A plasma at each end of the conductive element of the armature serves to conduct current between the conductive element and the adjacent conductor rail. A method of launching a projectile in an electromagnetic projectile launcher is provided in which a sliding conductive element conducts current between a pair of generally parallel launching rails until a selected velocity is achieved. At that time, plasmas are generated at each end of the conductive element. These plasmas serve to transfer current between the conductive element and the launcher rails for the remainder of the launch.

Line throwing device

Abstract: A line throwing device adapted to be launched from a riot gun or similar tubular launching device comprises an elongated projectile that fits in the tubular launching device, a fin assembly slidably mounted on the body of the projectile such that the fin assembly slides forwardly to permit the rear end of the projectile to be positioned in the launching device for launching and slides rearwardly to a flight stabilizing position at the rear of the projectile as the projectile is launched from the tubular launching device. A rocket engine is mounted in the rear of the projectile for propelling the projectile. An ignition mechanism comprising a conventional shotgun primer cap mounted in a plastic casing fits on the end of the rocket and is ignited by the trigger and firing pin of the gun. A line is coiled in a canister removably attached to the gun, with one end of the line being attached to a harness mounted on the projectile so that the line can be carried to the desired target.

Electromagnetic launcher with powder driven projectile insertion

Abstract: An electromagnetic projectile launching system is provided with an electromagnetic launcher portion and a chemically driven launcher portion The electromagnetic launcher portion includes a pair of generally parallel conductive rails, a source of high current connected to the rails, and means for conducting current between the rails and for propelling a projectile along the rails The powder driven portion includes a rifled barrel adjacent one end of the conductive rails and axially aligned with the conductive rails, and means for chemically propelling a projectile through the rifled barrel and into the bore of the electromagnetic launcher portion while causing the projectile to spin prior to its entry into the bore

The electromagnetic &#952; gun and tubular projectiles

Abstract: Unlike the better known rail gun, the θ gun applies the propelling force along the length of its projectile. This is shown to allow much greater acceleration of high fineness ratio projectiles for a given barrel pressure, allowing much shorter barrels for military applications. A computer code which simulates performance of the θ gun is described and experimental results from a few simple, low energy experiments show close agreement with code predictions. Trajectories and aerodynamic heating for three candidate military projectiles are calculated for vertical and horizontal atmospheric launches where initial velocity is as high as 3 km/s. The calculations indicate that in some cases a thin layer of heatshield (ablator) will be required to control projectile heating.

Electronic relativistic effects on L-shell ionization of atoms by light-ion impact

Abstract: The $L$-shell ionization cross sections by charged-particle impact have been calculated in the plane-wave Born approximation, using relativistic hydrogenic wave functions for the target electrons. The effects of the binding-energy increase due to penetration of the projectile and the Coulomb deflection of the projectile are taken into account. The calculated values are compared with the corresponding values obtained by other theoretical models as well as the experimental data. It is found that the present theoretical predictions are in satisfactory agreement with the experimental results for low-energy protons.

Electromagnetic projectile launcher with magnetic spin stabilization

Abstract: An electromagnetic projectile launcher is provided with a magnetic field in the path of the projectile. This field induces currents in conductors within the projectile or interacts with a magnetic projectile to produce a torque which imparts spin stabilization to the projectile. Arcuate conductive rails are brought together to form a cylindrical bore to accommodate the cylindrical projectile necessary for spin stabilization.

Relative velocity sensor for void sensing fuzes and the like

Abstract: A relative velocity sensor for projectile fuzes and the like provides adaptive penetration delay for maximum effectiveness. A pair of contact activated switches on the fuze spaced a known distance apart provide electrical signals useful for calculating the relative velocity of the projectile with respect to a target. An adaptive penetration delay circuit utilizes these signals to detonate the projectile after a delay period determined by the relative velocity. Low graze angle impacts will cause immediate detonation of the fuze. The invention provides simple, effective means for achieving adaptive target penetration delay with very low in-flight power consumption.

Electromagnetic launcher with high repetition rate switch

Abstract: An electromagnetic projectile launcher is provided with a cartridge-type switch for commutating current from a high current source to a pair of generally parallel conductive rails. A conductive cartridge switch in sliding electrical contact with the rails at the breech end includes a pressure chamber and aperture for receiving a projectile. An increase in pressure in the pressure chamber forces the projectile forward while forcing the cartridge rearward. Current is commutated from the cartridge to a conductive armature which subsequently propels a projectile along the conductive rails.

Launching mechanism for subcalibre projectile

Abstract: Launching mechanism for fine stabilized subcalibre projectile fired from a gun barrel having a smooth or rifled bore. The mechanism comprises a sabot equipped with fork joints in which are articulated a set of jaws having means for articulation in rotation, bearing means in the gun barrel, means for holding the projectile constituted by bosses and spacers, locking means for the jaws and optionally aerodynamic means for unfolding the jaws. The invention is applicable more particularly to projectiles for piercing armour plating.

Projectile for hand and shoulder weapons and a cartridge fitted with said projectile

Abstract: A projectile for hand and shoulder weapons has a cylindrical body and a nose, the longitudinal cross-section of the nose being defined by two concave lines which are symmetrical with respect to the axis of the projectile. An internal cavity formed within the projectile body and open at the end remote from the nose is at least partly filled with charge power which has been introduced into the cartridge case. The initial velocity thus imparted to the projectile is higher than that of a projectile of the conventional type and of the same caliber.

Surface Pressure Measurements on a Boattailed Projectile Shape at Transonic Speeds

Abstract: : Measurements of wall static pressures on a model with and without a boattail are reported. The model shape is similar to that of M549 projectile geometry. Data were acquired at Mach numbers of 0.91, 0.94, 0.96, 0.98, 1.10, and 1.20; angles of attack of 0, 2, 4, 6, and 10 degrees; and circumferential positions around the model in 22.5 degree increments. Some of the pressure data were integrated over the model to provide axial force and static stability coefficients. Results are presented in both graphical and tabulated form and some comparisons are made with computational results.

Gyroscopically steerable bullet

Abstract: A projectile body has a gyro mounted therein including a rotor and a mechanism for supporting the rotor for rotation about a spin axis initially coincident with the longitudinal axis of the projectile body and pivotable away from the longitudinal axis of the projectile body. The rotor is initially locked to the projectile body so that it is spun with the projectile body during launch. Thereafter, the rotor is unlocked and the projectile body is de-spun to a relatively slow rate of rotation while transferring angular momentum to the free spinning rotor which continues to rotate at a high rate relative to the projectile body. Rotationally phased steering commands, which are generated from on-board homing sensor signals or up-link data signals received from a remote error sensor, are applied to a linear actuator within the projectile body. The actuator pivots the spin axis of the rotor away from the longitudinal axis of the projectile body. The resulting precession torque of the spinning rotor induces a change in the angle of attack between the projectile body axis and the actual velocity vector of the projectile thereby inducing midcourse trajectory shaping.