Showing papers on "Projectile published in 1970"

Gas Gun for Impact Studies

Abstract: A detailed description of a 10.16 cm gas gun that has been designed and installed at Washington State University is presented. The design velocity is 1.5 mm/μsec; the maximum velocity achieved to date is 0.9 mm/μsec with an 1100 g projectile. Angular misorientation of the projectile with respect to the target surface is consistently below 0.5 mrad. Brief descriptions of ancillary instrumentation and equipment are also given.

Partitioning of energy in hypervelocity impact against loose sand targets

Abstract: Aluminum spheres were fired vertically into dry quartz sand in the light-gas gun facility at the NASA Ames Research Center. A velocity of 6.37 km/sec and a chamber pressure of 150 μ were used for all shots. Using an estimated impact pressure of 500 kb, heating of the target was computed to be 26% of the initial projectile kinetic energy, while ejecta absorbed 53%, both figures being very similar to those found earlier for basalt. Energy lost to compaction was 20% of the total initial energy, whereas in basalt it is negligible. Comminution in the already granular sand used about 8% of the energy, whereas for basalt this ranges from 10 to 24%. No observed ejecta velocities exceeded that of the impacting projectile. Most of the fused material, if any, was ejected, and there was an increase in density at the bottom of the crater due to compaction. The final shape of craters in sand emphasizes the importance of target strength at low stress levels.

Non-lethal projectile and launcher therefor

Abstract: A non-lethal projectile and launcher therefor for riot control and the like comprising a body formed from a relatively soft, pliant latex material compressed to projectile form and mounted within a restraining cup which in turn is mounted in a firing shell. The body at its rearward end includes retracted guidance structure that extends on the projectile being fired, a chamber at its forward end to receive a marking fluid for marking the target, and internal subdivisions in its mid portion designed to permit the body to expand laterally on impacting into a soft textured mass that flattens on impact to avoid injury to the target. The projectile launcher is in the form of a barrel assembly including a bell shaped muzzle which permits the projectile to be fired without jamming even when held against the target and braking slots for discharging the propelling gases rearwardly of the launcher to reduce recoil.

Inner shell ionization by heavy, charged particles and associated energy loss of the projectile

Abstract: The process ofL- andM-shell ionization of atoms by heavy, charged particles is analysed in detail by a semiclassical, time-dependent perturbation method. The target electrons are described by non-relativistic hydrogenic wave functions. For the projectile is assumed a well-defined straight-line path. The Coulomb deflection and the screening is partially taken into account.

A Mechanics Approach to Projectile Penetration

Abstract: : In the program reported in the paper, a mathematical model was developed which describes the mechanism of the normal penetration of metallic targets. The model considers all the forces acting on the projectile during penetration, bearing in mind that it is deformed during the penetration and that its effective mass increases during penetration due to the concomitant motion of part of the target mass. With the aid of the mathematical expressions the projectile's velocity after perforation can be calculated by substituting the information on the cavity diameter obtained experimentally. Another part of this program consisted of a series of penetration experiments. The experimental results for the velocity drop due to normal perforation of metallic plates were compared with the mathematical model. (Author)

On the Ignition of a Pre-Mixed Fuel by a Hot Projectile

Abstract: A theoretical study of the problem of ignition of a cold combustible mixture by a hot projectile is performed by approximating, firstly, the flow over its surface to a laminar flow of the mixture over a hot plate, and, secondly, the flow in the wake of the projectile to a plane laminar mixing of the cold unreacted mixture with the hot combustion products. Unlike the earlier analyses consisting of successive approximations and/or series expansions, the non-similar boundary layer equations are directly integrated by following a suitable numerical scheme. A characteristic parameter of the problem—the distance at which ignition occurs, which is defined by the presence of a temperature maximum—is obtained for different values of quantities relating to the properties of propane-air mixture, and to the speed as well as the dimensions of the projectile.

Computed Radial Stresses In A Concrete TargetPenetrated By A Steel Projectile

Abstract: This paper provides computed radial stresses and penetration depth for a concrete target that is impacted by an ogive-nose steel projectile at a velocity of 315 m/s. The computed results are in good agreement with recently published experimental results. Also included is a description of the concrete model.

High energy minimum lethality weapon system

Abstract: The disclosure relates to a weapon system comprising a launcher and a flexible low lethality projectile of relatively large mass adapted to be radially expanded during trajectory so as to present a relatively large impact surface to the target. The projectile has an initial relatively small cross section so as to be insertable in a conventional launcher. The launcher may have internal rifling grooves within the barrel to effect rotation of the projectile and radial expansion thereof due to centrifugal force. The relatively large area of contact on impact reduces unit area energy and therefore penetration to a minimum while maintaining high inertia energy thereby to accomplish a nonlethal incapacitation of a human target.

Gas-operated multiple shot projectile firing device

Abstract: A gas-operated multiple shot projectile firing device with a circular and rotatable magazine which includes a plurality of chambers, each of which holds a dart-like projectile. A lever is associated with the projectile device and performs the dual function of cocking the firing mechanism and rotating the dartfilled magazine such that a plurality of projectiles can be successively fired upon a single loading. The device is particularly suited for short range firing and may be designed for dart projectiles of various calibers.

Ammunition tracer system

Abstract: An ammunition tracer system having a retro-reflective trailing edge on all projectiles and a laser illuminator bore-sighted with the weapon sighting and viewing equipment. At the sighted target, the reflective trailing edge of the projectile reflects the laser rendering the projectile visible in the viewing equipment.

Spin-stabilized projectiles

Abstract: A projectile assembly includes a spin-stabilized projectile having a sub-calibre portion and a discardable sabot mounted on the sub-calibre portion. The sabot is connected to the projectile in such a manner as to prevent separation of the sabot from the projectile, while the rear end of the projectile assembly remains in the barrel of a gun bore from which the projectile assembly is fired, by reason of the axial force exerted on the projectile assembly by the firing gas pressure. The connection allows separation of the sabot from the projectile by the action of centrifugal force and air drag, after the rear end of the projectile assembly has left the muzzle of the gun barrel, by reason of the consequent rapid decrease of the axial force.

Dynamic tester for projectile components

Abstract: Projectile component testing. A modified projectile, containing components to be tested, is accelerated by means of a vacuum air gun into a spinning tube where it is set in spinning motion while simultaneously being decelerated. Deceleration is accomplished by means of a hydraulic mitigator capable of imparting rotational spin to the projectile while applying a predetermined rate of deceleration. The system is designed for rapid production line testing by means of a control system which starts the spin tube in motion and releases the projectile when a predetermined pressure has been established within the air gun. The control system also terminates the spin and actuates a fluid operated component to replace the mitigator to its start position within the spin tube. In order to provide a check on the polarity of power supplies being tested, a spin angle sensor is provided to transmit a signal for release of the projectile only when the spin tube is in a predetermined angular orientation.

Ballistic compression decelerator

Abstract: Projectiles are recovered from free-flight for analysis of flight effects on the projectile. Recovery is accomplished by converting kinetic energy into controlled heat of compression which is dissipated in several stages. Shock compression is used during supersonic velocities of the projectile and adiabatic compression is used during sonic and subsonic velocities. Decelerator tubes having diaphragms within them are precharged to high pressure in front of the projectile to minimize the decelerating distance. The final diaphragm may or may not break depending upon the adiabatic pressure buildup.

Range limited projectile system

Abstract: A close range projectile system having a reverse thrust rocket in the projectile which permits maximum projectile velocity and hitting power over short range only.

Apparatus for measuring the muzzle velocity of a projectile

Abstract: Apparatus for measuring the muzzle velocity of a projectile has a measuring system at the muzzle of the gun barrel. The measuring system has two relatively spaced coils through which the projectile passes for inducing two signal pulses. Means are provided for compensating for changes in the distance between the two coils due to variations of temperature including a temperature-dependent resistor and wherein the thermoelectric voltage measured across said resistor is used as a compensating voltage in an electronic compensating circuit. The electronic compensating circuit has a phase-inverting stage to which the signal pulses are to be applied, wherein the output of the phaseinverting stage is connected to the input of a modified monostable multivibrator.

Hypervelocity Impact -- Material Strength Effects on Crater Formation and Shock Propagation in Three Aluminum Alloys

Abstract: : The effects of material strength upon the transient response of thick aluminum targets to hypervelocity impact has been studied experimentally. Most experiments involved the normal impact of 2017 aluminum spheres at a velocity of about 7 km/sec. Material strength was varied by employing targets of 1100, 6061, and 7075 aluminum alloys. Flash x-ray techniques were used to measure accurately the rate at which the crater grew during the impact process. Crater growth rates were also measured for 1100 aluminum in four separate ranges of projectile velocity from 2.3 km/sec to 7.0 km/sec. Free surface velocity and Hopkinson fly-off disk techniques were used to measure values of the peak normal stress at various distances from the impact point (between 1 cm and 10 cm) at several related angles away from the projectile trajectory. The measurements of the variation of stress amplitude with distance into the target demonstrated significant non-hydrodynamic stress attenuation believed to be associated with propagation of an elastic relief wave from the rear of the impacting projectile. Numerical calculations yield reasonable agreement with experimental results, but many of the details are in question. Measurement of shock arrival time with quartz disk sensors confirmed the elastic-plastic behavior of the target material.

Numerical studies of ejecta characteristics behind thin plates

Abstract: A study of hypervelocity impact of spheres upon thin targets is described. The study was based upon numerical solutions utilizing the STEEP code. (STEEP is a two-dimensional Eulerian technique, based upon a hydrodynamic-e lastic-plastic model.) The cases considered are Al, Cu, and Cd spheres impacting at 0.75 and 1.5 cm/jusec (24,600 and 49,200 fps) upon like-material target plates, with the plate thickness being J of the projectile diameter. Results can be scaled to any impact case having the same ratio. From the numerical solutions, spatial plots showing the time-resolved response of the projectile and target are shown in the form of velocity, and principal stress fields. The primary objective of the solutions was to determine the characteristics of the debris clouds behind the targets. Curves are presented showing debris mass, axial momentum, and kinetic energy per unit solid angle intercepted on witness plates behind the targets. Information regarding the residual states of the debris materials is also given. YPERVELOCITY impacts produce extreme pressures in the projectile and target materials. When the target is thin relative to the projectile dimensions, these propagate through to the rear surface, thereby accelerating the target material. Subsequent pressure rarefactions shatter the projectile and target materials, and a debris cloud is ejected at high velocity behind the target. The effectiveness of thin metal plates in breaking up and dispersing compact hypervelocity projectiles into a cloud of tiny debris particles is the basis of "bumper" concepts for protecting structures against such impacts. With a properly selected bumper, the cumulative effect of the impacts of the debris particles on the protected structure will be less damaging than the effect of the original proj ectile. However, the debris itself will cause some damage to the protected structure, and means for absorbing the debris energy and for disbursing its momentum are sought. For the design of such absorbers, knowledge regarding the debris characteristics is needed. Experimental observations can be used to assess some debris characteristics, but such measurements are often difficult, and do not yield as complete a description as may be desired. Numerical techniques offer an alternative source of data, and can further be used to identify important mechanisms which operate in the formation and dispersion of the debris. In addition, numerical techniques can be applied to obtain data in experimentally inaccessible regions, e.g., extremely high impact velocities. Two-dimensional numerical techniques have been developed and applied to a range of hypervelocity impacts into semiinfinite and relatively thick targets,1"3 as well as into targets where the thickness is just sufficient to defeat the projectile.4 Using the STEEP code, detailed solutions have now been obtained to study the debris characteristics in the seven thin plate impact cases in Table 1. The hydrodynamic-elasticplastic model used in this code is described in Read.5 The numerical solutions of the seven cases treated permit a limited analysis of material property effects, impact velocity effects, and elastic-plastic strength effects. For these solu

Response of Materials to Impulsive Loading

Abstract: : Six major studies including Hypervelocity Impact, Planar Impact, Ballistic Velocity Impact Testing, Pebble Impact, Rain Erosion, and Foreign Object Damage, are carried out. In the Hypervelocity Impact studies the effects of material strength properties on crater growth were examined in thick targets, also the peak normal stress behind the shock wave was measured as a function of distance and angle. The response of thin targets to hypervelocity impact was examined as a function of the residual state of the debris material. Significant results are shown. Two methods to produce Planar Impacts are described with the merits and limitations of each discussed. Planar impact by explosive driven flyer plate was used to describe the behavior of shock loaded material in the presence of a phase change. Ballistic Impact Studies examined the response of both the projectile and the target. The Pebble Program supported the Space and Missile Systems Office in analyzing the problems of retro-fit hardening of vehicles against pebble impact and in extensive testing of proposed fixes. The Rain Erosion effort was basically an equipment development program to produce an instrument to simulate rain impacts at high velocities and to measure the damage caused by them in representative vehicle materials. The camera system developed is described. Initial laboratory investigations of Foreign Object Damage (FOD) to simulated aircraft compressor blades are described. (Author, modified-PL)

Single chamber rap having centerport inhibitor

Abstract: A rocket assisted projectile has a solid propellant charge within the projectile casing extending substantially throughout the length of the casing and has an inhibited centerport therein which axially extends substantially throughout the length of the propellant charge, and the solid propellant charge comprises a cast single explosive sensitized charge bonded to the casing and bonded to the inhibitor material of the inhibited centerport during cure of the cast charge with said charge having bifunctional characteristics to produce rocket thrust for the projectile in flight and high explosive blast of the projectile at target.

Device on weapon barrels for reduction of the angle jump of a projectile

Abstract: A device on gun barrels for the reduction of the angle jump of a projectile, which comprises at least one reinforcement member fitted to the forward range of a gun barrel, and is adapted to dampen bending oscillations occuring upon firing in the gun barrel.

Projectile for smooth barrel hunting guns or rifles with auxiliary wad provided with helical side tabs

Abstract: The invention concerns a projectile for smooth barrel hunting guns or rifles. The projectile is inserted into a cartridge housing the charge, the priming system and sealing wad of limited thickness. The projectile comprises a substantially spherical body made of lead or other suitable material and is provided in its lower section with a flat chamfered base. The spherical projectile includes an internal cavity connected to an auxiliary wad, cylindrical in shape and containing helical tabs formed by grooves. The diameter of the projectile and the auxiliary wad correspond to the internal diameter of the cartridge which houses the projectile.

Supersonic Magnus Measurements of the 10-Caliber Army-Navy Spinner Projectile with Wrap-Around Fins

Abstract: : A research configuration was formed by attaching wraparound fins in a cruciform arrangement to a 10-caliber Army-Navy spinner projectile. This configuration was tested in a supersonic tunnel to get the Magnus force and moment, as well as the normal force and pitching moment. Model spin rate was generated by means of fin cant.

Rocket assisted projectile

Abstract: A rocket assisted projectile round consisting of a cartridge, a rocket motor and projectile wherein the cartridge propels the rocket motor out of a firing tube and ignites ignition powder in the rocket motor. Thereafter, the rocket motor is ignited and it propels the projectile in flight.

Device for a projectile

Abstract: A device separable from a projectile arranged to be fired from a rifled barrel. The device includes a unit such as a flare supported by a parachute which is expelled from the projectile a predetermined time after firing of the projectile. The unit is placed in a container which is initially closed at one end by a bottom plate which also constitutes the bottom plate of the projectile and is capable of sustaining the powerful gas pressure generated when the projectile is fired. Upon expulsion of the container from the projectile by a suitable timing and expelling assembly, the container separates into several parts and a brake mounted on the unit is activated by the centrifugal force and causes a slowdown of the unit. The bottom plate which is also subject to the centrifugal force is pivotally connected to the unit by a pivot means which is eccentrically disposed with respect to the lengthwise center axis of the container and thus of the unit. The combined action of the centrifugal forces acting upon the brake and the bottom plate cause the latter to pivot into an angular position in which it is released from the pivot means and is thus ejected out of the linear path of the unit, thereby preventing collision with the same.

Archery bow with projectile

Abstract: A bow and missile device, the bow having a central opening integrally therein, so that a missile when impelled by the bowstring passes through the central opening. The missile is of spherical or other solid configuration, and has a pair of wings affixed to a slit in the missile so that the wings may be folded around the bow string and be grasped by the user to facilitate propelling the missile by means of the bowstring, through the central opening in the bow.

Warhead with a disintegrating jacket to house several projectiles

Abstract: A warhead with a disintegrating jacket to house several projectiles, in picular splinter projectiles. The projectiles are each equipped with an ignition and backfiring system and fall to earth individually after disintegration of the warhead jacket. They are then fired upwards by means of the backfiring charge ignited by the ignition system, the charge explosive then being detonated. The ignition system of each projectile consists of a time-delay fuze and an impact fuze. The time-delay fuze is initiated when the projectile impacts with relatively soft ground and ignites the backfiring charge after adjusted times differing at least partly for the individual projectiles. The impact fuze, however, effects an immediate ignition of the backfiring charge when the projectile strikes relatively hard ground.

Effects Of Lamination And Spacing On Finite Thickness Plate Perforation

Abstract: In determining ballistic limits and residual projectile characteristics for very thick targets (situations where the ratio of target thickness T to projectile diameter D exceeds 10), resort must frequently be made to constructing the target from a number of layers whose thickness is less than that of the monoblock target. This holds true for determining penetration depths in semiinfinite plates as well. This paper presents results of numerical simulations comparing projectile residual characteristics, primarily residual mass, for monoblock and equivalent thickness layered targets for a number of situations involving T/D 10. It is found that for thick plates, results obtained from layered target perforation compare favorably with those from monoblock targets provided that the layering is not excessive and care is taken to insure that the individual layers have the same material properties as the monoblock target. For thin targets, the correlation ranges from poor to non-existent. Introduction Impact and impulsive loading onto layered media targets consisting of different materials is a problem of long standing. It occurs naturally when dealing with impact effects into geological media, where different strata have different material properties. It can occur in the design of protective structures where materials of different density, strength and cross-sectional area are employed to reduce the intensity of the impact stress. This aspect of the impact problem is well understood and is covered in modern textbooks and reference books dealing with transient phenomena. Another aspect of layering involves the impact of projectiles onto targets consisting of multiple layers of plates of the same density] In impact testing, this often occurs when very thick targets need to be constructed yet the target material in question is not manufactured in the required thickness. Take, for example, the requirement to construct an effective "semi-infinite" target, one where the rear of the plate does not influence the penetration process. It is Transactions on the Built Environment vol 22, © 1996 WIT Press, www.witpress.com, ISSN 1743-3509 104 Structures Under Shock And Impact desired to build such a target of rolled, homogeneous armor (RHA) steel. The maximum thickness of RHA commercially available is 20.32 cm. At this thickness, uniformity of material properties is a problem, as is cost. Hence, targets for deep penetration studies are often constructed by using a number of plates of smaller thickness, stacking them until the desired thickness is reached. This target stack is then contained in some fashion (e.g. trapped, welded at the periphery) and the test conducted. In the course of testing the restraints are broken and the front and rear plates are observed to move considerable distances, even for tests involving target plates weighing several terns. Each layer acts as a momentum trap and the outermost layers dissipate the residual energy through rigid body motion. Several questions must now be answered before the test results may be accepted as valid: (a) does the penetration event occur on the same time scale as the rigid body motion of the target plates? In other words, is a layered target an effective simulant of a monoblock target? (b) what is the effect of layering as the number of plates required to simulate the monoblock thickness increases? (c) if target plates do separate before completion of the penetration/perforation process, what is the effect on the penetration depth (or, if a perforation, on the projectile residual mass and velocity) These questions must be answered for three classes of targets: (a) thin targets (T/D 10) Thin and Intermediate Thickness Targets For thin and intermediate thickness targets the answers may be readily inferred from the existing literature. In their study of containment structures, Zaid, ElKalay and Travis (1973) point out that for very thin plates (thicknesses < 2 mm), lamination greatly reduces the resistance of the target plate to ballistic impact. Netherwood (1979), conducting in situ pressure measurements of impacted plates found the laminated target to be much weaker than a solid one of the same thickness so that the mechanism of penetration of a laminated target was different than that for a solid target. Nixdorff (1984) examined analytically the effect on lamination on the ballistic limit for up to five layers and found considerable differences as the number of layers increased. Similar conclusions were reached by Segletes and Zukas (1989) in a numerical analysis Transactions on the Built Environment vol 22, © 1996 WIT Press, www.witpress.com, ISSN 1743-3509 Structures Under Shock And Impact 105 of laminated plates. Other studies could be cited but these suffice to show that for thin targets, lamination can alter the response mechanism under impact loading and fail to correlate with the behavior of a solid target, especially if the number of layers is large. The problem for intermediate thickness targets can be seen from the results of the following calculations. The ZeuS code [Segletes and Zukas (1987), Janzon et al (1992), Zukas (1993)], a two-dimensional explicit finite element code for fast, transient analysis on personal computers, was used to calculate the impact of a 64.5 gram S-7 tool steel projectile with length-todiameter (L/D) ratio of 5 into a single RHA plate with a thickness of 3.18 cm. The projectile had a diameter of 1.3 cm and a striking velocity of 1164 m/s. Experimental data was taken from the report by Lambert (1978). The experimentally determined values of projectile residual mass and residual velocity were 22.9 grams and 223 m/s, respectively. ZeuS calculations indicated a residual mass of 25.5 grams and a residual velocity of 233 m/s. These were deemed acceptably close. Next, a series of calculations was undertaken where the solid target above was assumed to consist of 2, 4 and 6 layers, each with properties identical to those of the solid target. Penetration of the four-layer target at various times is shown in Figure 1. The variation of projectile normalized residual mass ( mjm^ and normalized residual velocity (V,IV^ V striking velocity) can be seen in Figures 2 and 3. With the 4-layer laminated target, the difference between Lambert's data for the solid target and the computed residual masses is 43% while for the residual velocity it is 143%. The differences continue to increase with increasing lamination. Even though the plates making up the laminated target have the same density and material properties as the solid target, the differences noted above could be anticipated. The plates in the laminated target are not restrained and are allowed to slip freely over each other. As they separate after the passage of the projectile, a free surface is created. The inability of a free interface to support rarefaction waves changes the stress wave propagation characteristics of multiplate penetration events at early times. As these stress differences are integrated in time, the difference between the simulations becomes more visible, with the multiplate case demonstrating more bending than the equivalent solid plate case (Figure 4). This can also be inferred from plate theory which gives for the bending stiffness of the plate E7 /12(1 -v*), where E is the elastic modulus, T the plate thickness and v Poisson's ratio. Since bending stiffness follows plate thickness to the third power, simply cutting a monoblock plate in half reduces its bending stiffness by a factor of 8. Transactions on the Built Environment vol 22, © 1996 WIT Press, www.witpress.com, ISSN 1743-3509

Integral propellant case ramjet projectile

Abstract: A gun launched projectile utilizing the cartridge case as a ramjet burner. The round is loaded into the gun in normal fashion and the igniter is introduced through the rear of the cartridge case. Upon ignition the entire unit is ejected from the gun at high velocity with air inlets opening to allow ramjet engine operation.