Increase Volume, Ballistically Matched Projectile for Enhanced Effect

Description

STATEMENT OF GOVERNMENT INTEREST

The invention described was made in the performance of official duties by one or more employees of the Department of the Navy, and thus, the invention herein may be manufactured, used or licensed by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

BACKGROUND

This application relates generally to ammunition. In particular, replacement ammunition for an MK244.

The MK 244 20 mm is a specific type of ammunition designed for use in the MK 15 Phalanx Close-In Weapon System (CIWS), an advanced naval defense system used to counter incoming threats such as anti-ship missiles and aircraft. The Phalanx CIWS is an automated, radar-guided gun system that consists of a radar guidance unit, a fast-rotation barrel gun, and the ammunition handling system. The system is capable of acquiring, tracking, and engaging enemy threats autonomously, providing a last line of defense for naval vessels.

In FIGS. 1A-B, the prior art is shown. The MK 244 20 mm ammunition 11 is also known as the Enhanced Lethality Cartridge (ELC) due to its design improvements over earlier types of CIWS ammunition. The MK 244 is an Armor-Piercing Discarding Sabot (APDS) round. This means it is designed to penetrate armor by focusing its kinetic energy into a smaller, more concentrated point upon impact. The sabot 13, a carrier that houses the baseline projectile 15, discards upon firing (See FIG. 1B), allowing the denser baseline projectile to continue towards the target at higher velocity. The MK244 further includes a pusher 17, a cartridge case 19 that contains a propellant 21, and a primer 23. As the name suggests, the ammunition is 20 mm in diameter, which is standard for the Phalanx CIWS. The primary role of the MK 244 ammunition, within the context of the Phalanx CIWS, is to protect naval vessels from high-speed, maneuvering anti-ship missiles and aircraft threats. The APDS nature of the round makes it particularly effective against armored or hard targets. The development and deployment of the MK 244 20 mm ELC rounds represent ongoing efforts to enhance naval defense capabilities against evolving threats, ensuring that ships equipped with the Phalanx CIWS can effectively defend themselves in a wide range of combat scenarios.

SUMMARY

This specification outlines the design and material composition for a ballistically matched projectile intended for use with the MK244 gun system. The objective of this novel projectile is to add material (and volume) to a projectile while matching the ballistic curve and mass of the existing ammunition, allowing rounds to be interlinked. The novel projectile design maintains the original (also called baseline) projectile's mass while increasing its volume. This is achieved by employing a two-part construction comprising an ogive and a body, utilizing materials of different densities.

Generally, a projectile's ballistic performance (how well and how far it flies) is a function of its mass and aerodynamic characteristics, a function of the drag coefficient and its diameter. Higher mass and lower drag result in a better ballistic characteristic. Typically, a reduction in overall density (same mass, greater volume) diminishes ballistic performance. However, in the case of this novel projectile, it is ballistically matched. Ballistically matched ammunition incurs less changes on a gun weapon system which eases integration and allows for a larger, less dense projectile to be matched to a higher density projectile. This novel projectile achieved ballistic matching by developing a longer projectile with a larger diameter and lower drag coefficient, resulting in the same ballistic performance. The novel projectile achieves a lower drag coefficient using an optimized ogive and a more aggressive boattail. Since the material was significantly lighter than tungsten, the novel projectile uses a projectile formed from two joined bodies: An ogive made of the lighter material and a projectile made of tungsten. The assembly body mass is identical to the baseline projectile. Through analysis, the inventors found that a spline joint bonded the bodies so they would survive the gun-launch environment.

BRIEF DESCRIPTION OF THE DRAWINGS

These and various other features and aspects of various exemplary embodiments will be readily understood with reference to the following detailed description taken in conjunction with the accompanying drawings, in which like or similar numbers are used throughout, and in which:

FIGS. 1A-B shows the prior art;

FIG. 2 is a comparison between the novel projectile and the baseline prior art;

FIG. 3 is a detailed dimensional view of an embodiment of the novel projectile; and

FIGS. 4A-B is a detailed dimensional view of an embodiment of the novel projectile.

DETAILED DESCRIPTION

In the following detailed description of exemplary embodiments of the novel projectile, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration specific exemplary embodiments in which the novel projectile may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the novel projectile. Other embodiments may be utilized, and logical, mechanical, and other changes may be made without departing from the spirit or scope of the present novel projectile. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present novel projectile is defined only by the appended claims.

The design objective of ballistically matching the projectile of the MK244 system is achieved by maintaining the baseline projectile's 15 mass while increasing the volume and changing the shape.

As shown in FIG. 2, maintaining the mass while increasing the volume is achieved by employing a projectile 31 with a two-part construction comprising an ogive 35 and a body 37, utilizing materials of different densities. In the present application, the body 37 is formed from a dense material such as tungsten and the ogive 35 is formed from a material that is less dense than tungsten such that the combined mass of the ogive 35 and the body 37 match the mass of the baseline projectile 15. Further, to match the mass of the solid tungsten baseline projectile 15 the volume of the novel projectile 31 is increased by increasing the length of projectile 11 as compared to the baseline projectile 15. FIG. 2 shows a side by side view of increased length and volume, ballistically-matched projectile 31 and the prior art projectile 11. In some embodiments, the volume of the projectile 31 is 8.53 cm³ while the volume of the baseline projectile 15 is 6.199 cm³ and the maximum diameter of both is 16 mm.

Once the volume is increased, the aerodynamic characteristics of the baseline projectile 15 are matched by the novel shape of projectile 31. The novel shape is achieved by using an ogive 35 and a more aggressive boattail 33 to the body 37. In the embodiment shown, the shape of the ogive 35 is determined by the formula:

y = ( - 0 . 3 ⁢ 1 ⁢ 4 ⁢ 9 ⁢ 6 ) * ( X 1 . 7 ⁢ 7 ⁢ 9 ) 2 / 3 ( 1 )

As shown in FIG. 2, boattail 39 is more aggressive than boattail 19. As shown in FIG. 3, boattail 39 is a compound boattail with a first slope 51 and a second slope 53, wherein the first slope 51 is more aggressive than the second slope.

As discussed above, the baseline projectile 15 is replaced with a two-part novel projectile 31. This requires that the ogive 35 and the body 37 are joined. In one embodiment, the ogive 35 and body 37 are interconnected using a spline joint 45. This design ensures a robust and secure connection, capable of withstanding the forces experienced during gun-launch. The spline joint 45 facilitates a seamless aerodynamic profile and structural integrity. The spline joint 45 transmit rotary motion and torque between the ogive 35 and the body 37 while allowing them to maintain alignment. Spline joints offer advantages such as high torque transmission capacity and precision without compromising performance.

Both projectiles 31, 11 are enclosed in sabots corresponding sabots 33, 13. As shown in this view, the diameter of the sabots 33, 13 remain the same. Further, the plug 41 and the pusher 43 remain the same which further eases integration into the CIWS.

In FIG. 3, the novel projectile 31 includes a flat (or aft) end 55 having a first radius A is (5.0000 cm, 0.20 in″). A compound boattail 39 directly adjoining the flat end. The compound boattail includes a first taper (or slope) 51 extending from the flat end 55 and including the first radius A (5.0000 cm, 0.20 in″), ending at a second radius B (6.5000 cm, 0.26 in″) and extending a first predetermined distance C (3.0000 cm, 0.12 in″) from the flat end and a second taper (or slope) 53 continuing from the first taper 51 and including the second radius B, ending at a third radius D (8.0000 cm, 0.31 in″) and extending a second predetermined distance E (13.7757 cm, 0.54 in″) from the flat end. The projectile 31 further includes a cylindrical section 57 directly adjoining the compound boattail 39 at the third radius F, the cylindrical section 57 having a constant radius equal to the third radius F and extending a third predetermined distance F (12.5360 cm, 0.49 in″) from the end of the second taper. The projectile 31 further includes an ogive 35 directly adjoining the cylindrical section 57, the ogive section having a tapered profile G defined by Eq. (1) converging towards a tip 59 ending a fourth predetermined distance H (1.8288 cm, 0.07 in″) from a diminishing point 61 of the tapered profile of the ogive 35. The diminishing point 61 is a fifth predetermined distance I (71.6787 cm, 2.82 in″).

FIGS. 4A-B show a comparison between the ballistic performance between the baseline projectile 15 and the novel projectile 31. Line 71 (shown as baseline in the figure) shows the performance of baseline projectile 15 and Line 73 (shown as ⅔ Ogive in the figure) shows the performance of projectile 31 as measured in range over time. As shown in the analysis, the range over time characteristics of the two projectiles matches the delta drop at 1 km is 0.00879889 m and at 2 km the delta drop is −0.0417656 m. Line 75 (shown as baseline in the figure) shows the performance of baseline projectile 15 and Line 77 (shown as ⅔ Ogive in the figure) shows the performance of projectile 31 as measured in Mach over range.

While certain features of the embodiments of the novel projectile have been illustrated as described herein, many modifications, substitutions, changes and equivalents will now occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the embodiments.