Drag reduction system

Abstract

A drag reduction system, more specifically a forward mounted drag reduction system for use on an extended range artillery shell, includes a forward end comprising a fuse, an aft located base unit and located therebetween a shell body defining a cavity which comprises a payload, a forwardly located gas generator capable of generating a gas flow, and an ignition device to ignite the gas generator after the shell is launched.

Claims

1. An extended range, gun-launched artillery shell, comprising: a forward end comprising a fuze; an aft located base unit; a shell body located between the fuze and the base unit, the shell body defining a cavity which comprises a non-gas generating payload; a forwardly located gas generator comprising a plurality of separate portions of an energetic material each configured to generate a gas flow; and a plurality of ignition devices each configured to separately and independently activate the respective portion of the energetic material of the gas generator, wherein the gas generator comprises a plurality of nozzles located on an ogive surface portion of the shell body adjacent to the fuze, each nozzle configured to be independently activated so as to provide directional control by causing an unsymmetrical laminar gas flow to reduce air resistance against the shell body.

2. The shell according to claim 1, wherein the forwardly located gas generator is located between the fuze and the shell body.

3. The shell according to claim 1, wherein the gas flow is directed along an outer surface of the shell body.

4. The shell according to claim 3, wherein the gas flow is directed substantially rearwardly towards the aft base unit of the shell.

5. The shell according to claim 1, wherein at least one of the nozzles is a directionable nozzle.

6. The shell according to claim 1, wherein the gas generator provides a portion of gas flow which is substantially normal to the shell, to increase air resistance.

7. The shell according to claim 1, wherein the gas generator is activated independent of the launch of the shell.

8. The shell according to claim 1, wherein the plurality of nozzles includes at least one of a pyrotechnic controlling nozzle and a propellant gas controlling nozzle.

9. The shell according to claim 1, wherein the energetic material includes at least one of a pyrotechnic composition and a propellant composition.

10. An extended range, gun-launched artillery shell, comprising: a shell body defining a cavity configured to contain a non-gas generating payload; a fuze located at a forward end of the shell body; a base unit located at a rear end of the shell body; a forwardly located gas generator comprising a plurality of separate portions of an energetic material each configured to generate a gas flow; and a plurality of ignition devices each configured to separately and independently activate the respective portion of the energetic material of the gas generator, wherein the gas flow generator comprises a plurality of nozzles located on an ogive surface portion of the shell body adjacent to the fuze, each nozzle configured to be independently activated so as to provide directional control by causing an unsymmetrical laminar gas flow to reduce air resistance against the shell body.

11. The shell according to claim 10, wherein the forwardly located gas generator is located between the fuze and the shell body.

12. The shell according to claim 10, wherein the gas flow is directed along an outer surface of the shell body.

13. The shell according to claim 10, wherein the gas flow is directed substantially rearwardly towards the base unit of the shell.

14. The shell according to claim 10, wherein the plurality of nozzles includes at least one of a pyrotechnic controlling nozzle and a propellant gas controlling nozzle.

15. The shell according to claim 10, wherein the energetic material includes at least one of a pyrotechnic composition and a propellant composition.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Exemplary embodiments of the device in accordance with the invention will now be described with reference to the accompanying drawings in which:

(2) FIG. 1 shows a cross section of a prior art base bleed shell.

(3) FIG. 2 shows a cross section of forward mounted bleed unit, according to the invention.

(4) FIG. 3 shows a trajectory of a projectile fitted with a forwardly mounted gas generator system.

(5) FIG. 4 shows a cross section of the nozzle configuration.

DETAILED DESCRIPTION

(6) Turning to FIG. 1 there is provided a cross section of a, prior art, base bleed assisted shell 1. A fuze 3 is located at a forward end of the shell body 8, and at the rear of the shell body is a base unit 5. The base unit 5 contains a base bleed unit 7, which contains an energetic material 9, and an ignition device 9a.

(7) If the shell is to be spun, a driving band 6 is located around the circumference of the shell body 8, towards the rearward end. The band 6 engages with the rifling grooves in the launch barrel (not shown), to impart spin.

(8) After the shell 1 is launched, the ignition device 9a will be caused to function as a result of one of many stimuli, such as for example a delay composition initiated during launch or activated by a high g force or high spin rate force. The ignition device 9a will ignite the composition 9, which provides a gas flow 4. The gas flow 4 from the base bleed unit 7 fills the void 2a created by the high speed air flow 2 passing across outer surface of the shell body 8, as the shell 1 moves through the air.

(9) In the absence of a base bleed unit 7, the air flow 2 creates disturbed air flow behind the shell base which causes further drag on the rear of the shell.

(10) FIG. 2 shows a cross section of a projectile 10, as defined herein. The projectile 10 comprises a projectile body 18, with a fuze 13 located at a forward end 12, and at the rear end 14 of the projectile body is a base unit 15. The base unit 15 may have a general boat tail configuration.

(11) The gas generator 17, is located forward of the projectile body 18, and is preferably located on an ogive surface portion 11 of the projectile body 18. The gas generator 17 is most preferably located between the fuze 13 and the projectile body 18. The gas generator 17 may be a separate device from the fuze or it may form an integral part of the fuze 13. The gas generator 17 is ignited by ignition device 19. The stimuli to activate the ignition device may be any of the commonly used stimuli, such as, delay compositions which are initiated during launch or an electronic timer, an RF signal from a remote source, or a mechanically activated ignition device, such as those activated by a high g or high spin rate forces.

(12) The gas generator 17 provides a gas flow 24, via nozzle 20, so as to provide a near laminar gas flow (thick line) 21, which flows over the contours of the projectile body 18. The gas flow 24 provides a low friction surface to interact with the air flow 22 such that the projectile body 18 experiences less air resistance from the air flow 22 as the projectile body 18 travels through the air. The gas flow 24, is of sufficient force to ensure that the air flow 22 does not move into the void 25 behind the base unit 15.

(13) The projectile body 18 contains a payload 23, which may be HE, illumination or any commonly used payload. As this design does not need a base unitthis payload may also take the form of a system/set of sub-systems with capacity for rear dispensing.

(14) If the projectile is to be spun, a driving band 16 may be located around the circumference of the projectile body 18, towards the rearward end 14. The band 16 engages with the rifling grooves in the launch barrel (not shown), to impart spin.

(15) FIG. 3 shows schematic of a ground plane xz, a non-bleed projectile may follow a typical trajectory 43 with a final target distance 41 along the x-axis. The bleed assisted projectile as defined herein, would start out with the same launch angle, but would follow an extended path trajectory 44 due to experiencing less air resistance and therefore would be able to travel a further distance to the final target 42.

(16) FIG. 4 shows a side view of a nozzle 52, with a portion of propellant 51, which when combusted, provides gas flow 53.