Projectile

• US 6,581,522 B1
• Filed: 02/18/1993
• Issued: 06/24/2003
• Est. Priority Date: 02/18/1993
• Status: Expired due to Fees

• Current Assignee: Gerald J. Julien, Ronald H. Bondy
• Original Assignee: Gerald J. Julien, Ronald H. Bondy
• Inventors: Julien, Gerald J., Bondy, Ronald H.
• Primary Examiner(s): TUDOR, HAROLD JAY
• Application Number:
  US08/018,841
• Time in Patent Office: 3,778 Days
• Field of Search: 102/374, 102/380, 102/430-433, 102/446, 102/501, 102/700, 102/439, 102/514, 102/516, 102/517, 102/518, 102/507-510, 102/519, 42/77, 244/3.23
• US Class Current: 102/431
• CPC Class Codes: F42B 12/34 expanding before or on impact, i.e. of dumdum or mushroom type
• CPC Class Codes: F42B 12/74 of the core or solid body
• CPC Class Codes: F42B 5/192 Cartridge cases characterised by the material of the casing wall cartridge bags F42B5/38

Abstract

A projectile for being propelled toward a target includes a cylindrical body of Type 55 Nitinol that has a soft martensitic state that is readily deformed by rifling in the bore of a gun barrel to form grooves which ride on the rifling to spin the projectile. The Nitinol has a low coefficient of friction with the steel barrel and is sufficiently strong to prevent shedding particles or depositing projectile material in the bore. On impact with the target, the Nitinol undergoes a strain-induced shift to an ultra-high strength state in which the projectile is capable of remaining intact and concentrating its full energy on the small area of contact for maximal penetration and damage to the target instead of mushrooming widely and spreading its energy over a wide area as conventional projectiles do. Projectiles in the form of bullets, shotgun slugs, penetrating warheads, caseless ammunition and artillery shells are described.

Claims

1. A projectile for being propelled through a rifled bore of a gun barrel by gas pressure in said bore behind said projectile, comprising:

a cylindrical body of a shape memory alloy having a martensitic state, said body existing in an unprestrained condition in said martensitic state prior to and during propulsion through said bore, said body in said martensitic state having an initial yield strength of less than 20 KSI and a cold-worked yield strength of greater than about 200 KSI;

whereby said shape memory alloy in said projectile has an initial yield strength that is soft enough to facilitate formation of helical grooves in said projectile when propelled through said rifled bore for spinning said projectile, and is sufficiently strong to prevent lands on said projectile around said helical grooves from shearing off of said projectile under high cup pressures behind said projectile in said bore, and said shape memory alloy has a high strength induced by cold working which occurs on impact with a target that ensures that said projectile will remain intact upon impact with a target.

2. A projectile as defined in claim 1, wherein:

said shape memory allow has an initial yield strength of less than about 15 KSI and a maximum cold-worked strength of greater than 250 KSI, whereby said projectile has excellent target penetration characteristics.

3. A projectile as defined in claim 1, wherein:

said projectile includes a pointed front end that resists deformation by impacts normally encountered in the receive of a gum to maintain a high ballistic coefficient despite rough handling.

4. A projectile as defined in claim 1, wherein:

said projectile has a shear strength of greater than 4 KSI prior to propulsion through said bore, whereby said projectile will remain intact during passage through said bore without shedding material.

5. A projectile as defined in claim 1, wherein:

said shape memory alloy is Nitinol in a solid form.

6. A projectile as defined in claim 5, wherein:

said shape memory alloy is Type 55 Nitinol.

7. A projectile as defined in claim 1, wherein:

said projectile includes a front end of Type 60 Nitinol for enhanced penetration of a target.

8. A projectile as defined in claim 1, wherein:

said high cup pressures are sealed in said bore behind said projectile by high interfacial pressure between said cylindrical body and said bore that is made possible by low friction and sufficiently high yield strength to prevent straining of said cylindrical body that would lower said high interfacial pressure.

9. A projectile as defined in claim 1, wherein;

said shape memory alloy is an environmentally benign, non-toxic, substantially inert material in solid form that will not pollute the environment nor poison wildlife, plants or humans.

10. A method of propelling a high velocity, high accuracy projectile toward a target, comprising:

inserting a projectile made of a shape memory alloy material into the breach of a rifled bore of a gun barrel, said projectile having an initial yield strength of less than 20 KSI which increases to an ultimate yield strength of greater than 200 KSI when subjected to about 2% cold-work;

generating a high pressure gas volume in said breach behind said projectile;

propelling said projectile axially along said rifled bore;

forming helical grooves in said projectile by interference of said projectile and said rifling in said bore;

retaining all of said projectile material on said projectile during passage thereof along said bore, whereby said rifled bore remains clean and free of particles of said projectile;

said retaining step includes cold working said projectile in land regions around said helical grooves by said helical groove forming step and thereby transforming said land regions from an initial low yield strength condition to a yield strength condition more than 10 times stronger than said initial low yield strength condition; and

spinning said projectile by interaction of said high pressure gas volume in said bore behind said projectile and said rifling in said grooves in said projectile.

11. A caseless gun cartridge for firing from a bore of a gun barrel toward a target, comprising:

an axially elongated Nitinol shell with an external diameter about equal to the diameter of said gun barrel bore, and having a forwardly tapering nose at a front axial end, a cylindrical thin walled body containing a charge of propellant;

a rear closure at the axial end opposite said front axial end, said rear closure containing a primer for initiating said propellant, and a plurality of openings through which gas generated by said propellant exits said shell to propel said shell toward said target.

12. A caseless gun cartridge as defined in claim 11, further comprising:

a lead slug fixed within the interior of said forward end of said shell.

13. A caseless gun cartridge as defined in claim 11, wherein:

said closure includes a central opening formed integrally with said rear closure for receiving and holding said primer.

14. A caseless gun cartridge as defined in claim 13, wherein:

said central opening opens rearwardly in said closure for receiving said primer, and opens inwardly into said cylindrical body for directing blast from said primer into said charge of gunpowder to initiate said gunpowder.

15. A caseless gun cartridge as defined in claim 11, further comprising:

indexing structure in said shell for indexing said shell at a predetermined axial position in a bore of a gun barrel.

16. A method of propelling a projectile from a gun toward a target, comprising:

inserting a round of caseless ammunition into a breach of said gun, said round having a shell of shape memory alloy including a forwardly tapering front end and a rearwardly extending cylindrical body, said shell containing a propellant sealed therein by a rear closure containing a primer;

closing said breach with a bolt to seal said round in said breach;

initiating said primer in said round and thereby initiating said propellant contained within said shell;

generating high pressure propelling gas in said shell by burning said propellant;

pressing said cylindrical body against said bore of said gun with said high pressure gas to seal said round in said bore against escape of said high pressure gas between said bore and said body;

driving said shell forwardly in said bore away from said breach and toward a muzzle of said gun with said high pressure gas while retaining said high pressure gas in said bore by sealing engagement of said cylindrical body against said bore.

17. A method as defined in claim 16, wherein said shape memory alloy is Nitinol.