Patent Grant
7752977
The invention relates in general to projectiles and in particular to projectiles that rapidly decelerate upon impact.
In the case of many munitions, it is desirable for the munition to deliver its payload, whether explosive or nonexplosive, upon impact. In these munitions, it is assumed that the point of impact is the desired target. Thus, it is undesirable that the munition continue its travel after impact with the target. Continued travel past the target makes the munition less effective. In the case of projectiles or penetrators, it is necessary to provide a means for slowing the projectile after impact.
Known methods of accomplishing this task usually involve a soft deformable metal nose, some sort of ring shaped flange, or a molybolt-style device that opens petals. All of these designs increase the presented area of the penetrator through deformation of their structure. The “soft” metal approach usually involves lead, which is very dense. Dense metals are difficult to slow down due to their increased kinetic energy and increased mass. Ring flanges are satisfactory until at least one point on the circumference of the flange fails, and then the entire ring fails catastrophically. The molybolt-style devices are effective until individual petals break off. As the petals break off, the braking action of the molybolt-style device is decreased.
A principle purpose of the present invention is to provide a means for slowing a projectile in the most rapid fashion possible on impact in media ranging from sand, soil, concrete, metals, plastics, water, flesh, bone, etc.
One aspect of the invention is a decelerating apparatus which includes a sleeve having a forward end and a rear end. A plurality of grooves are formed in the sleeve. Each groove begins at the forward end of the sleeve and has a depth that decreases from the forward end towards the rear end of the sleeve. More particularly, the plurality of grooves are helical and the depth of each groove at the forward end is large enough so that the groove cuts completely through the sleeve at the forward end.
Another aspect of the invention is a projectile having a body with a decelerating apparatus attached to the body. The decelerating apparatus includes a sleeve having a forward end and a rear end. The sleeve has a plurality of grooves formed in it. Each groove begins at the forward end of the sleeve-and has a depth that decreases from the forward end towards the rear end of the sleeve. More particularly, the plurality of grooves are helical and the depth of each groove at the forward end is large enough so that the groove cuts completely through the sleeve at the forward end.
The invention will be better understood, and further objects, features, and advantages thereof will become more apparent from the following description of the preferred embodiments, taken in conjunction with the accompanying drawings.
In the drawings, which are not necessarily to scale, like or corresponding parts are denoted by like or corresponding reference numerals.
As shown in detail in
As best seen in
The plurality of grooves 22 define deformable petals 28 therebetween. In the embodiment shown in
The sleeve 16 shown in the
Upon impact, the DA 14 deforms in such a way as to increase the presented area of the projectile 10 into the flow of material around it. This action absorbs the kinetic energy of the projectile 10, allowing it to slow down. The DA 14 enables two distinct mechanisms to take place during deformation. First, although the forward end of the grooves 22 are cut completely through the sleeve 16, the remaining portion of the grooves 22 are not cut all the way through the sleeve 16. Thus, in forming the petals 28, the sleeve material has to tear along the grooves 22, thereby consuming large amounts of energy. Second, as the grooves 22 tear and the sleeve material folds back to form the petals 28, the “mushrooming” nature of the helical petals 28 and their tendency to deform into a clumped mass also absorbs energy.
In operation, the impacting media deforms the petals 28 rearwards forcing the sleeve 16 material to tear along the helical grooves 22, effectively smashing and mushrooming the petals 28 into a mass of mangled metal in a ring shape near the ends of the grooves 22. The combination of the tearing of the sleeve 16 material and deformation within the petals 28 both consume energy. In addition, as the mushrooming ring is formed, there is a dramatic increase in presented area that increases the consumption of energy as the projectile 10 impinges on the impact material. As the helical petals 28 deform they become intertwined and locked, providing some structural benefit and helping them to stay in the flow of media longer. Similarly, as the petals 28 continue to deform under more and more applied force, they simply “peel” back the material of the sleeve 16 like peeling the paper covering off of a drinking straw.
More particularly, the DA 14 is made of a lightweight material, such as low density metals like Al, Mg, Ti, or polymers, or composites. An advantage of using lightweight materials is that their lower density makes them easier to decelerate, thus enabling more dynamic projectile design and function. In contrast, in the past, the purpose of soft metals and expanding tips in bullets was to present more surface area to thereby increase lethality, but there was no desire to reduce kinetic energy. Thus, in the past, the use of high density lead was appealing. The density of the expected media that the DA 14 will impact determines the material of the DA 14. For example, a plastic or thin metal sleeve may be appropriate for impact with water or flesh; a thick plastic or thin metal sleeve for impact with sand, plastic, or thin metals; and a thicker, stiffer metal sleeve for impact with hard soil or thicker metals.
DA 14 may be fabricated by any of various techniques including casting, molding, machining, or extrusion. DA 14 may be fabricated integrally with the forward portion of a projectile's body 12, or as an add-on structure.
While the invention has been described with reference to certain exemplary embodiments, numerous changes, alterations and modifications to the described embodiments are possible without departing from the spirit and scope of the invention as defined in the appended claims, and equivalents thereof.
Finally, any numerical parameters set forth in the specification and attached claims are approximations (for example, by using the term “about”) that may vary depending upon the desired properties to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of significant digits and by applying ordinary rounding.
The inventions described herein may be manufactured and used by or for the Government of the United States of America for government purposes without the payment of any royalties thereon or thereof.
| Number | Name | Date | Kind |
|---|---|---|---|
| 871825 | Schupmann | Nov 1907 | A |
| 5164538 | McClain III | Nov 1992 | A |
| 5569874 | Nelson | Oct 1996 | A |
| 6182574 | Giannoni | Feb 2001 | B1 |
| 6581522 | Julien et al. | Jun 2003 | B1 |
| 6679178 | Mihaylov et al. | Jan 2004 | B2 |
| 7222573 | Pontieri | May 2007 | B2 |
