GB1601935A

GB1601935A - Projectile

Info

Publication number: GB1601935A
Application number: GB2849677A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1977-07-07
Filing date: 1977-07-07
Publication date: 1981-11-04
Also published as: FR2396948A1; DE2829591A1; BE868785A; FR2396948B3; JPS5439999A

Description

(54) PROJECTILE (71) I, GEOFFREY MARTIN SPENCE, a British Subject of ' Trenoweth', The Firs, Lanner, Nr. Redruth, Cornwall, do hereby declare the invention, for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to ammunition for guns, especially firearms.

In accordance with the present invention there is provided a gun projectile comprising at least two ring aerofoils forming a contmu- ous section of a generally tubular body, a first of the aerofoils forming the nose of the projectile.

In one embobdiment of the invention the tubular body further includes a sealing disc retained in a recess formed in the bore of a tail section of the tubular body, the disc being released only when the tail section is deformed radially outwardly in response to the nreqsure of the propellant gas when the projectile is propelled through the barrel of a gun.

In one alternative embodiment, the bore of the tubular projectile is formed with a recess for receiving a propellant, the recess being located between a combustible sealing disc which seals the said bore toward the rear end of the bore. The sealing disc burns through soon after the bullet leaves the barrel of the gun, and combustion of the propellant in the bullet then combines with the pressurized air entering the combustion chamber to provide a ram-jet which maintains the velocity of the bullet.

By way of example only, two bullets embodying the invention will now be described with reference to the accompanying drawings in which: Fig. 1 is a longitudinal section through a bullet embodying the invention; Fig. 2 shows the bullet of Fig. 1 crimped in a cartridge case; Fig. 3 shows the bullet of Fig. 1 being discharged through the barrel of a firearm, and Fig. 4 is a longitudinal section of a modified armour piercing/trace bullet incorporating a ram-jet.

The bullet illustrated in Figs. 1 and 2 consists essentially of a hollow tube having a nose section 10, an intermediate section 20, and a tail section 30. Both sections 10 and 20 comprise ring aerofoils. The intermediate section 20 is provided primarily to compensate for the loss of mass which results from forming the nose section as a hollow tube instead of as a conventional solid bullet. The bullet is thus longer than a conventional solid bullet but may have about the same weight.

The tail section 30 is provided to releas ably retain a sealing disc 12 at the sail end of the tubular bore.

The bullet is retained in a conventional car tridge case 40 by crimping the case around the intermediate section 20 of the bullet. On firing the cartridge, the bullet is propelled along the barrel 50 of a firearm and spin stabilised in the same manner as a conventional solid bullet. This is shown in Fig. 3.

To prevent propellant gas escaping through the bore 11 of the tube, a sealing disc 12 is crimped within a recess formed in the tail portion 30 of the tube. On firing, the gas pressure built up behind the bullet expands the rear skirt 31 agains the wall 50 forming the bore of the barrel through which the bullet is fired. The expanded position of the skirt.

31 is shown in Fig. 3. This releases the grip of the skirt on the sealing disc although the disc remains held in place by the gas pressure behind the bullet. The disc is eventually ejected backwards by air pressure when the bullet is approximately 20' from the barrel.

Alternatively, as shown in Fig. 4, a fixed combustible disc 60 may be used in place of the disc 12, the partially exposed face 61 being flame retardant to prevent accidental firing if a burning object is pushed down the barrel of a firearm containing the bullet.

The disc 60 may be formed, for example, of a magnesium alloy. It has a reduced crosssection at its centre so that burn-through occurs first at the centre. The disc is ignited by the combustion of the propellant gases in the cartridge when the cartridge is fired.

The bullet also includes an internal recess containing a fuel pellet. The burn-through disc 60 is first crimped in position across the rear end of the bore 11 through the ring aerofoil 1.

The fuel pellet 62 is then inserted into its recess in the bore 13 (which is a continuation of the bore 11). A specific area of the fuel pellet may be given a flame retardant coating so that the pellet is ignited at a certain point and burns in a certain direction. In any event, the burning pellet is ignited by the propellant gases at about the same time as the disc 60.

As soon as disc 60 burns through (when the bullet is about 20 feet from the barrel), pressurised air enters the bore 13 from the bore 11. The combustion of the fuel pellet together with further combustion of the disc 60 heats the pressurised air which therefore expands. A ram-jet is therefore produced, the air exhausting through the venturi 14. This additional propulsion maintains the velocity of the bullet by compensating for the normal air drag The additional propulsion continues for as long as the fuel pellet 62 or disc 60 continues to burn. The fuel pellet may contain a propellant mixture and/or trace compositions.

At high mach numbers at ground level, the ram-jet has a high propulsion efficiency and a low propellant consumption. By using a high specific impulse propellant a 5.56 mm bullet of the type shown in Fig. 4 can, when constructed of suitable "hard" material, pierce light armour.

Trace rounds use a smaller propellant pellet which produces a higher velocity so compensating for the lack of bullet mass in order to provide similar range characteristics to the armour piercing bullet.

The bullet shown in Figs. 1 and 2 is more efficient than a conventional solid bullet since not only is the range increased but it provides a flatter trajectory to simplify aiming. It is particularly suited for use in 5.56 mm weapons. When compared with a standard M 193 bullet, the following results were obtained, both bullets having a weight of 55 grains, a diameter of 0.224 inches, an MV of 3250'/sec., and a form factor of 0.56 (IngaWs Tables).

Property M 193 5.56mm Bullet 5.56mm Aerofoil Bullet Sectional Density 0.156 0.267 Ballistic Coefficient 0.278 0.476 Velocity at 218 yds 2460 ft/sec. 2790 ft/sec.

Velocity at 546 yds 1534 ft/sec. 2180 ft/sec.

Velocity at 1093 yds 895 ft/sec. 1389 ft/sec.

Kinetic Energy at 218 yds 743 ft/lbs. 955 ft/lbs.

Kinetic Energy at 546 yds 288 ft/lbs. 583 ft/lbs.

Kinetic Energy at 1093 yds 98 ft/lbs. 237 ft/lbs.

WHAT I CLAIM IS: 1. A gun projectile comprising at least two ring aerofoils forming a continuous section of a generally tubular body, a first of the aerofoils forming the nose of the projectile.

2. A projectile according to Claim 1 in which the tubular body further comprises a tail section extending from the rear of the second ring aerofoil, and wherein the tail section includes a sealing disc retained in a recess formed in the bore of the tubular body, the disc being released only when the tail section is deformed radially outwardly in response to the pressure of the propellant gas when the projectile is propelled through the barrel of a gun.

3. A projectile according to Claim 2 in which the sealing disc is crimped in the said recess.

4. A projectile according to Claim 1 wherein a sealing disc is located across the bore of the tubular body, the disc being formed of combustible material which is ignited by the propellant gases when the projectile is propelled through the barrel of a gun.

5. A projectile according to Claim 4 wherein the disc has a variable burn-through rate such that, in use, initial burn-through occurs substantially in the centre of the disc.

6: A projectile according to Claim 5 in which the variable burn-through rate is con

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. containing a fuel pellet. The burn-through disc 60 is first crimped in position across the rear end of the bore 11 through the ring aerofoil 1. The fuel pellet 62 is then inserted into its recess in the bore 13 (which is a continuation of the bore 11). A specific area of the fuel pellet may be given a flame retardant coating so that the pellet is ignited at a certain point and burns in a certain direction. In any event, the burning pellet is ignited by the propellant gases at about the same time as the disc 60. As soon as disc 60 burns through (when the bullet is about 20 feet from the barrel), pressurised air enters the bore 13 from the bore 11. The combustion of the fuel pellet together with further combustion of the disc 60 heats the pressurised air which therefore expands. A ram-jet is therefore produced, the air exhausting through the venturi 14. This additional propulsion maintains the velocity of the bullet by compensating for the normal air drag The additional propulsion continues for as long as the fuel pellet 62 or disc 60 continues to burn. The fuel pellet may contain a propellant mixture and/or trace compositions. At high mach numbers at ground level, the ram-jet has a high propulsion efficiency and a low propellant consumption. By using a high specific impulse propellant a 5.56 mm bullet of the type shown in Fig. 4 can, when constructed of suitable "hard" material, pierce light armour. Trace rounds use a smaller propellant pellet which produces a higher velocity so compensating for the lack of bullet mass in order to provide similar range characteristics to the armour piercing bullet. The bullet shown in Figs. 1 and 2 is more efficient than a conventional solid bullet since not only is the range increased but it provides a flatter trajectory to simplify aiming. It is particularly suited for use in 5.56 mm weapons. When compared with a standard M 193 bullet, the following results were obtained, both bullets having a weight of 55 grains, a diameter of 0.224 inches, an MV of 3250'/sec., and a form factor of 0.56 (IngaWs Tables). Property M 193 5.56mm Bullet 5.56mm Aerofoil Bullet Sectional Density 0.156 0.267 Ballistic Coefficient 0.278 0.476 Velocity at 218 yds 2460 ft/sec. 2790 ft/sec. Velocity at 546 yds 1534 ft/sec. 2180 ft/sec. Velocity at 1093 yds 895 ft/sec. 1389 ft/sec. Kinetic Energy at 218 yds 743 ft/lbs. 955 ft/lbs. Kinetic Energy at 546 yds 288 ft/lbs. 583 ft/lbs. Kinetic Energy at 1093 yds 98 ft/lbs. 237 ft/lbs. WHAT I CLAIM IS:

1. A gun projectile comprising at least two ring aerofoils forming a continuous section of a generally tubular body, a first of the aerofoils forming the nose of the projectile.

trolled by varying the cross-section of the disc, the cross-section being reduced at the centre.

7. A projectile according to Claim 6 in which the disc is located toward the rear end of the first ring aerofoil, and wherein a portion of the bore of the tubular body located rearwardly of the disc is provided with a recess to form an expansion chamber for compressed air passing through the burnt-through disc during flight of the projectile whereby further combustion of the disc heats the compressed air in the expansion chamber to produce a ram-jet.

8. A projectile according to Claim 7 in which the recess is filled with a solid fuel propellant whereby the compressed air is further heated by combustion of the propellant.

9. A projectile according to Claim 7 in which the rear end of the expansion chamber is formed as a venturi whereby the ram-jet afflux exhausts through the venturi.

10. A projectile according to Claim 4 in which the bore of the first ring aerofoil.

converged toward the sealing disc to provide a compression duct for air entering the bore during flight of the projectile, and in which a portion of the bore of the tubular body located rearwardly of the sealing disc is recessed to provide an expansion chamber for the pressurized air, the disc having a variable cross-section such that, once ignited by the firing of the projectile, it firstly burns through at its centre to provide communication between the compression duct and the expansion chamber, and then continues to burn to heat the pressurized air in the expansion chamber.

11. A projectile according to Claim 10 in which the rear end of the expansion chamber is formed as a venturi such that a ram-jet is produced by the combustion in the expansion chamber, the jet efflux exhausting through the venturi.

12. A projectile according to Claim 10 in which the recess is at least partially filled with a solid fuel propellant which is ignited during the flight of the projectile.

13. A round of ammunition for a gun, the round comprising a projectile according to any one of the preceding claims and a cartridge case containing a propellant, the cartridge case being crimped around the outside of the second ring aerofoil.

14. A projectile according to Claim 1 and substantially as herein described with reference to Figs. 1 to 3 of the accompanying drawings.

15. A bullet according to Claim 1 and substantially as herein described with reference to Fig. 4 of the accompanying drawings.