Showing papers on "Projectile published in 1977"

Projectile motion with air resistance quadratic in the speed

Abstract: We consider two‐dimensional motion of a projectile experiencing a constant gravitational force and a fluid drag force which is quadratic in the projectile’s speed. The equations of motions are coupled nonlinear equations. Their solutions have general properties which are easily visualized, although much different from those obtained when a drag force is neglected. Because of these features a study of these equations would provide an interesting counterpoint to the already familiar case of no drag. In this paper we derive simple approximate solutions to the equations of motion for both short and long times. A numerical example is used to compare these approximate solutions with accurate results obtained by numerical integration from an exact but implicit solution. Finally, the origin of the quadratic drag force is discussed.

Guidance and Control of a Cannon-Launched Guided Projectile

Abstract: A 155-mm cannon-launched guided projectile, called Copperhead, employing semiactive laser homing guidance, has been developed to improve artillery effectiveness against moving hard-point targets. Development of the Copperhead guidance and control configuration was motivated by the need for pinpoint accuracy and ruggedness sufficient to survive peak cannon-launch loads of 9000 g. Conceptual tradeoffs favored gravitybiased proportional navigation, implemented through use of a strapdown seeker with optically coupled gyro, aerodynamic tail control, and a roll position control. A unique application of a pitch/yaw gyro enabled the projectile to establish a vertical reference after launch. The configuration developed was demonstrated successfully in 8 out of 12 flight tests during its advanced development.

An Investigation of Oblique Perforation of Metallic Plates by Projectiles

Abstract: An experimental and analytical study was performed on the mechanics of oblique perforation of metallic plates by projectiles. The purpose was to determine the dependence of the velocity drop on the angle of impact for prescribed mechanical and physical properties of the projectile and the target plate. The ballistic experiments were carried out with 0.22-in.-caliber lead bullets on target plates of commercially pure aluminum and an aluminum alloy which ranged from 2.0 to 6.0 mm in thickness. Transient measurements were taken which included high-speed photographs of the perforation process. The theoretical model that had been developed previously by the authors for the case of normal perforation was modified to include the effects of the angle of impact. The experimental observations for the present test conditions indicate that the main modification to the analysis is the use of the total projectile path as the effective target-plate thickness. Reasonably good agreement between the experimental and theoretical results was obtained.

Gaming surface contact detecting systems

Abstract: A gaming surface contact detecting system for detecting the presence of a particular type of projectile upon touchdown of the projectile on any gaming surface or surfaces and for locating the position of touchdown of the projectile in relation to the gaming surface or surfaces. The gaming surface contact detecting system includes a projectile with at least one surface portion of detectable material, and a surface signal means. The surface portion of the projectile may include a contact recognition surface such as a chemical surface or an electrical conductive surface. The surface signal means may include a second chemical surface or may include a sensing means. The surface signal means is connected on at least a portion of the gaming surface. Upon positive contact between the projectile and the surface signaling means, a signal is initiated that signals the touchdown of the projectile that bounces off the surface signaling means on the gaming surface.

Magnetoflyer method for measuring gas‐gun projectile velocities

Abstract: The magnetoflyer method has been developed as a convenient and fiducial technique for measuring projectile velocities from propellent and gas guns. The velocity is estimated from the time interval between two electromotive force signals when the projectile, which includes a small ferrite magnet, passes through two pick‐up coils. It was confirmed that the method was available up to 5 mm/μs.

Coulomb deflection effects in ion-induced K-shell ionisation

Abstract: Assuming a hyperbolic Kepler orbit for the projectile, an analytical expression for the monopole projectile path factor is derived in the semiclassical approximation. The case of an attractive potential is also included. An improved Bang-Hansteen deflection factor is found to be approximately valid for arbitrary electron wavefunctions. The method is applied to calculations of the monopole contribution to K-shell ionisation using relativistic electron wavefunctions.

Electromagnetic projectile accelerator

Abstract: Electromagnetic projectile accelerator comprising stationary coreless coils arranged in a row thus forming a tube. On the interior wall surface of said tube electrically opposite poled plates are mounted establishing an electric field. The magnetic projectile moving through the said electric field generates an alternating switching mode in the respective electromagnetic coils whereby the acceleration of the projectile within the tube is performed.

Electron capture into excited projectile states in collisions of 100 keV Nez+ (z=1,2,3,4) with He, H2 and Ar

Abstract: By means of absolute light intensity measurements between 2000 and 6500 AA cross sections have been determined for electron capture into excited projectile states during collisions between 100 keV Nez+ (z=1,2,3,4) and different target gases. Total single-electron-capture cross sections have been obtained by measuring ion-current attenuation. There is direct experimental evidence that capture into excited states is related to the energy defect of the respective reaction and furthermore, that for higher projectile charge states an important part of the single-electron-capture process is caused by capture into excited states with moderate exothermic energy defects.

Penetrating projectile system and apparatus

Abstract: A projectile having a length to diameter ratio greater than 6 to 1 is propelled from a launcher by a propellant charge toward a rock target at velocities of 500 ft./sec. and higher to more efficiently penetrate the rock for excavation purposes.

Projectile propulsion and control in a gas-powered gun

Abstract: A projectile is propelled from the gun when a valve that controls the gas storage chamber of the gun is momentarily unseated, thereby admitting a short burst or charge of gas into the space immediately behind the projectile. The barrel that confines and controls the projectile during its movement out of the gun is itself driven rearwardly by spring action to accomplish unseating of the valve through an actuating stem at the rear of the barrel, and during such rearward movement of the barrel, the projectile is carried therewith so as to reduce the volume of the space behind the projectile in which the gas may expand before acting upon the projectile. After a predetermined amount of rearward movement, the projectile is released to thereby prevent interference with its propulsion from the gun, and return movement of the barrel forwardly after valve actuation is terminated short of its fully forward position, thereby minimizing the increase in the gas expansion space created by movement of the barrel and stem forwardly during firing. Stopping such forward movement in this way also positively precludes any opportunity for the barrel and actuating stem to oscillate in a rebounding manner between the spring that drives the barrel rearwardly and the spring controlling the valve, such activity otherwise causing a series of gas discharges after the projectile has already left the gun.

Fishing rod and projectile firing gun

Abstract: A fishing rod, having a longitudinal bore for the reception of an elongated projectile, replaces the conventional barrel and is secured to the magazine of a compressed gas fired pistol. The bore includes a lateral port communicating with a charge of gas under pressure. The elongated projectile is closed at its forward end and includes an axial socket open at its other end. A tubular bolt is slidably received in the bore of the fishing rod and the axial socket of the projectile. The bolt is closed at its rearward end but includes a lateral port communicating with the lateral port in the bore and with the axial socket of the projectile, whereby the bolt transfers the charge of gas to the projectile for firing thereof. A monofilament line, wound on a spin-cast reel supported by the fishing rod, has its free end attached to the projectile for retrieving the projectile after being fired at a target.

Trajectory Perturbations of Fin-Stabilized Projectiles Due to Muzzle Blast

Abstract: The flow at the muzzle of a gun during launch of fin-stabilize d projectiles is investigated both experimentally and analytically. Optical and flash radio graph surveys are used to define the muzzle blast growth and projectile r dynamics. Based upon the experimental results, an analysis is developed of the loadings exerted by propellant gases upon the projectile. It is shown that both in-bore and muzzle blast flowfields must be considered. The inbore flow is modeled as a one-dimensional, unsteady expansion, whereas the muzzle blast flow is approximated as a two-dimensional, quasisteady, underexpanded jet. The effect of launch gasdynamic loadings upon projectile motion is calculated and is shown to compare favorably with experiment. Nomenclature = area of a single fin = lift and moment coefficients = speed of sound = gun tube diameter = distance between obturator and fins = projectile transverse moment of inertia

Deflection effects in inner-shell ionization

Abstract: Recently a method of calculating inner-shell ionization has been formulated in which Hartree-Fock wave functions are employed and all terms in the Born series retained. Results have so far been presented only in the energy region where projectile deflection effects are of little importance. In this paper it is shown how the time-dependent problem can be solved just as conveniently for hyperbolic classical projectile paths that result from the nuclear repulsion. The method is applied to the impact-parameter dependence of $K$-shell ionization by protons on copper in the energy range 0.5 to 2 MeV. Excellent agreement is found at the lower energy with experiments of Andersen et al. Poorer agreement is obtained in the higher-energy regime.

Electronic relativistic effects and Coulomb deflection of the projectile in L-shell ionization of atoms by light ions

Abstract: The semiclassical approximation is applied to the calculation of L-subshell Coulomb ionization of atoms by light ions, using relativistic Coulomb wavefunctions for the electrons. The Coulomb deflection of the projectile is taken into account by the tangential approximation. Numerical results are presented both for total cross sections and for the impact dependence of the ionization probabilities. There is considerable improvement in the agreement with experiment for low-energy projectiles. At high energies the relativistic effects and the deflection effects partially cancel each other.

Comparison of target and projectile ionization near 0/sup 0/ for He/sup + +/,He/sup +//Ar at 2 MeV. [Energy spectra and angular distributions]

Abstract: Energy spectra of electrons with velocities near the ion velocity were measured and angular distributions were derived for both the He/sup + +//Ar and He/sup +//Ar systems at 2 MeV. The data were compared to charge-exchange theories for target ionization and to an electron-scattering model for projectile ionization. It was found that in the forward direction target ionization and projectile ionization were indistinguishable on the basis of the ejected electron spectra. (AIP)

Frangible target practice projectile

Abstract: In order to provide a frangible projectile for use in aircraft target practice, a combination steel and plastic projectile is constructed. This unit consists of a steel cup into which a glass reinforced plastic ogive is injection molded. During the same injection molding process, a plastic rotating band is installed around the periphery of the projectile.

Toy projectile launching apparatuses

Abstract: An apparatus for use in launching toy projectiles which comprises a piston or bellows having one side pneumatically connected to an operating mechanism and its opposite side arranged so as to be capable of launching a projectile from the apparatus when moved towards that projectile at a sufficient speed, the operating mechanism exhibiting a chamber whose size can be suddenly changed by squeezing, or a manual blow, or the release of a stressed spring, to alter the pneumatic pressure applied to the piston or bellows and displace it launchingly towards a projectile, the initial volume of the chamber preferably being rapidly restored to suck the piston or bellows back to substantially its initial position after each launching operation.

A membrane model for the response of thin plates to ballistic impact

Abstract: T he axisymmetric response of an infinite plate to an impacting projectile is determined analytically on the hypothesis that, for large deformations, a ductile plate behaves to a good approximation like a membrane under uniform tension. The lowest projectile velocity that results in perforation (the ballistic limit), and the residual velocity after perforation, then are determined on the basis of a critical-strain failure criterion. A figure of merit that depends only on the material properties of the target and characterizes the resistance of the material to impact appears naturally in the analysis. Variations in the ballistic limit with target thickness and projectile dimensions can be determined when this figure of merit is known. The theoretical ballistic limit and residual velocity for a steel cylinder impacting a titanium plate are found to agree with available measured values. Further support for the membrane model and an estimate of its range of validity are obtained by comparing the maximum displacement of an impulsively-loaded, circular membrane with experimental data for circular plates.

A rectangular-bore gas gun

Abstract: Design details and measured performance are presented for a laboratory gas gun with a novel rectangular bore. Projectiles weighing 0.5 g have been accelerated to 300 m s-1. This design eliminates axial rotation of the projectile which is possible in a cylindrical-bore gun, and provides important advantages in some impact experiments.

Apparatus for generating an electrical ignition current in a fuze of a projectile

Abstract: An apparatus for generating an electrical ignition current in the fuze of a projectile to be fired from a weapon, comprising an induction coil arranged in the projectile, a magnet for generating a magnetic field, a bipartite yoke, one part of which is located at the projectile and the other part at the weapon barrel, for producing a change in the magnetic flux upon passage of the projectile through the weapon barrel. According to one embodiment the part of the yoke located at the weapon barrel comprises a number of ferromagnetic rings and paramagnetic rings arranged between the ferromagnetic rings. The part of the yoke located at the projectile body comprises a substantially cylindrical body member having a substantially disc-shaped flange for the reception of the induction coil as well as a soft iron disc. With this arrangement the magnet is a permanent magnet which is disposed between this cylindrical body member and the soft iron disc. The axis of the induction coil substantially coincides with the projectile axis, and the aforesaid ferromagnetic and paramagnetic rings are arranged at the end of the weapon barrel. It is possible, according to another embodiment, to use instead of a permanent magnet, an electromagnet located at the mouth of the weapon and containing such ferromagnetic and paramagnetic rings, with the yoke at the weapon barrel being in the form of a triple-arm yoke carrying two oppositely polarized electromagnetic coils.

Ammunition rack for tank turret

Abstract: Mechanism for releasably retaining a projectile in an upright position win a military tank. A solenoid-controlled pawl releasably engages a side surface of the projectile to retain said projectile in position. Energization of the solenoid withdraws the pawl from the projectile surface, thereby enabling the soldier to remove the projectile from the mechanism.

Terminally corrected projectile

Abstract: An apparatus for correcting the terminal portion of the ballistic trajectory of a projectile. The projectile is initially fired at a target in a manner to cause the projectile to rotate in flight. At least one detector is mounted on a front surface of the rotating projectile to rotate with the projectile and scan the target area in a spiral pattern. A laser beam is directed to hit the target and a reflected portion of the beam energizes the scanning detector. The energized detector transmits an ignition signal to activate a trajectory correction motor and an associated nozzle having a plug that is weakened in response to the signal. The activated motor operates during the terminal portion of the trajectory to generate a thrust pulse that is passed through the nozzle having the weakened plug. The thrust pulse is directed by the nozzle to correct the trajectory of the projectile.

Game apparatus including a resilient projectile with a plurality of legs

Abstract: A game apparatus includes a projectile made of resilient foam material which is in the shape of an enlarged "jack" and a plurality of bats having soft impact areas which are used to strike the projectile so as to move the projectile between a pair of goal posts which are also preferably resilient. Generally, the game apparatus is used to play a game which resembles field hockey, but may be played indoors or in a relatively confined outdoor area. By utilizing relatively "soft" bats and a relatively soft projectile, the chance of injury is reduced. Since the projectile has the shape of a "jack" it will often follow an irregular trajectory and will not roll far after hitting the ground.

Projectile with sabot

Abstract: A sabot projectile including a sabot, a subcaliber projectile and a hood arranged in front of the sabot and surrounding at least a part of the projectile. The hood is coupled to the sabot and/or the projectile and is separable therefrom. The sabot is provided with at least one bore extending in the longitudinal direction and arranged for exposure to propellant gases upon firing of the sabot projectile from the barrel of a weapon and for directing the propellant gases onto the hood for accelerating the hood relative to the projectile while the sabot projectile is within the barrel of the weapon.

Frangible projectile for gunnery practice

Abstract: A sintered projectile having the same ballistic characteristics as a conventional combat projectile is provided with controlled strength properties and predetermined breakage lines. As a result, small, high drag fragments are produced on impact which minimizes ricochet hazards and provides a safer practice round.

Reconfigurable toy with optical elements

Abstract: A toy including a number of press-fitting parts configurable as a rocket plane is provided. A number of the parts include optical elements which may function as a kaleidoscope, or, in a second configuration, as a periscope. Some of the parts may be assembled to form a blow-gun for discharging a toy projectile at a toy target.