Projectile

About: Projectile is a research topic. Over the lifetime, 13047 publications have been published within this topic receiving 115563 citations.

The added mass of a spherical projectile

Abstract: When a ball moves through the air, the air exerts a force on the ball. For a sphere moving at constant velocity with respect to the air, this force is called the drag force and it has been well measured. If the sphere moves with a nonconstant velocity there are additional forces. These “unsteady” forces depend on the sphere’s acceleration and, in principle, also on higher derivatives of the motion. The force equal to a constant times the acceleration is called the “added mass” because it increases the effective inertia of the sphere moving through the fluid. We measure the unsteady forces on a sphere by observing the one- and two-dimensional projectile motion of light spheres around the highest point. The one-dimensional motion is well described by just the usual buoyant force and the added mass as calculated in the ideal fluid model. This measurement is an excellent experiment for introductory physics students. For spheres in two-dimensional projectile motion the downward vertical acceleration at the highest point increases with the horizontal velocity. This effect can be described by an additional force proportional to the speed times the acceleration.

Gyroscopic stabilization of launch package in induction type coilgun

Abstract: The aim of this paper is to study the problem of gyroscopic stabilization of the launch package in induction type coilguns. This result can be obtained by utilizing a double-feed induction coilgun which provides rotation to the launch package while it is accelerating. Such a launcher is comprised of two coils, one generating a travelling magnetic field (and consequently the axial acceleration) the other a rotating magnetic field for the rotation of the projectile. Electromagnetic analysis, based on a cylindrical sheet current model, allows one to determine, as a function of the two slips (in the translation motion and in the rotation motion) all the electric, magnetic and mechanical quantities. Thermal and mechanical stress are determined too. Finally the results for a launcher, in which a 2 kg projectile is accelerated, are reported. For this application time dependence of the principal electromechanical quantities are shown. A comparison with the same launcher running as a linear induction launcher is developed too.

Projectile Penetration in Granular Soils

Abstract: Results from centrifuge and 1-g model tests of projectile penetration into granular soils are described. Solid spherical projectiles in four calibers were fired into uniform samples of dry sand at approximately 305 m/s. Comparison to full-scale test results verified the suitability of the centrifuge testing technique for this type of problem. Power relationships between projectile penetration depth and projectile mass-to-area ratio are developed. Statistical analyses show that these functions describe the combined 1-g and centrifuge test results with a high degree of accuracy. Test results are compared to predictions of penetration depth based on Young’s equation. Suggestions for improvements in Young’s equation are made, including elimination of an arbitrary mass-scaling factor, use of a soil description based on physical properties of the soil, and use of a soil-specific exponent with the projectile mass-to-area ratio.

Target acquisition and tracking system

Abstract: A projectile tracking system for acquiring and precisely tracking a projectile in flight in order to reveal the source from which the projectile was fired. The source is revealed by the back projection of a 3-dimensional track file. In preferred embodiments the system is installed on a vehicle, such as an un-manned blimp or other aircraft, road vehicle or ship, for locating and destroying small arms fire directed at the vehicle. A kill system may also be included on the vehicle to destroy the source of the projectile.