STABILIZER FOR A CANNON PROJECTILE

Abstract: A cylindrical device (20) connected to the nose of a projectile (22) for imparting spin to the projectile fired from a non-rifled bore of a cannon. The device has at least two coaxial, adjacent, and integrally connected cylindrical segments of different diameter (32 and 34). The segment (32) having the larger diameter is positioned most rearwardly of the projectile, relative to the nose of the projectile, and the periphery of this segment has circumferentially spaced angled slots (34) for catching air moving past the projectile to spin the projectile. The segment with the smaller diameter (34) attaches the cylindrical device (20) to the aft end of the nose of the projectile (22) and directs the flow of air to and through the angled slots (38) of the segment having the larger diameter (32).

Description: I STABILIZER FOR A CAHNON PROJECTILE The invention described herein may be manufactured, used and licensed by or for the Government for Governmental purposes without the payment to us of any royalties thereon. Field of the Invention This invention relates to a device for a projectile, or a portion of a projectile for effecting spin of the projectile in flight, after the projectile is fired from a smooth bore cannon. Background of the Invention In the science of ballistics, it is conventional wisdom that shock waves, emanating from a projectile in flight and traveling faster than the speed of sound, interfere with and break-up the flow of air close to the aft or back end of the projectile. The disruption of air flow affects the flight of the projectile. In order to compensate for or overcome such perceived interference and to impart spin to a projectile fired from an non-rifled or smooth bore system, the projectile 120, as shown in prior art Fig. la, is manufactured to include a boom or extension 122 which provides distance between the nose 124 and fins 126. In effect, the boom ensures that the fins, which do not extend beyond the diameter of the body of the projectile, contact intact air flow. Alternatively, a projectile, as shown in Fig. lb may have expanding fins 128. In such a case, the fins are hinged and spring loaded to the body of the projectile so that as the projectile exits the bore of a cannon on firing, fins 128 expand ;. the smaller diameter attaches the cylindrical device to the aft iι end of the projectile and directs the flow of air to and through j; the angled slots of the segment having the larger diameter. Brief Description of the Several Views of the Drawings Fig. la shows a prior art projectile having an extended boom and fins attached to the rear of the boom; neither the diameter of the boom, nor the length of the fins extend beyond the caliber or largest diameter of the projectile; Fig. lb shows a prior art projectile having expanding spring loaded fins that extend beyond the largest diameter of the projectile; Fig. 2 shows a side view of the stabilizer of the invention; Fig. 3 shows a front view of the stabilizer of Fig. 2; Fig. 4 is a perspective view of the stabilizer more clearly showing slots on the periphery of the segment of the stabilizer having the largest diameter; Fig. 5 shows a projectile having a spine-shaped nose with the stabilizer of the invention connected to the rearward end of thereof. Detailed Description of the Invention. The stabilizer 20 of the invention is shown in Fig. 5 attached to the rearwardmost (tail) end of a projectile 22. Projectile 22 may be, for example a tank round for a 120 mm smooth bore system. Stabilizer 20 ensures that the projectile spins when fired from such a smooth bore or non-rifled system. Projectile 22 possesses a spine nose forwardmost (front) portion 24 and a rearward or aft cylindrical portion 26 having stabilizer 20 attached thereto. The diameter of cylindrical portion 26 is slightly smaller than the inside diameter of the of segment 32. The peripheral arrangement of the slots is shown more clearly in Fig. 3. As more clearly shown in Fig. 4, angled slots 38 are defined by substantially parallel side walls 40 walls 40 angled at thirty degrees, relative to the longitudinal | I axis 29 of the segments 32 and 34, and traveling faster than the . I i i speed of sound, will spin at a rate of twenty-five revolutions ι per second. The steady state is reached in seconds. Adjacent, integrally connected, and coaxial to cylindrical section or flange 32 is cylindrical section 34. Cylindrical section 34 has a diameter smaller than the diameter of cylindrical section 32 and an axial length 48 longer than the axial length 36 of cylindrical section 32. The diameter of cylindrical section 34 is approximately 102.6mm, and the axial length 48 is approximately 43.6mm. The difference in diameters between cylindrical segments 32 and 34 defines the depth of slots 38. A threaded member 50, the diameter of which is not critical, so long as it is not greater than the diameter of cylindrical segment 34, is attached to segment 34 and connects stabilizer 20 of the invention to a complimentary connecting member, not shown, of projectile 22. Member 50 alternatively may be a bayonet mount (not shown) and member 50 additionally may include, as shown in Fig 2, auxiliary ring clamp threads 52 for mating with a ring clamp of a projectile. As described above, the device can be connected to the rear end of either a spine-nosed 24 (Fig. 5) or ogive-nosed shaped projectile and may be made in dimensions to fit a projectile of any smooth bore system. In operation, as a projectile exits the bore of the non-rifled cannon, above the speed of sound, air passes over axial length 48 of reduced diameter cylindrical segment 34 and is directed through angled slots 38 on the periphery 37 of cylindrical segment 32. As shown in Fig. 2, the walls 40 of slots 38 have a negative slope and as air passes through slots 38 the projectile 22 spins in a clockwise direction (when review form the rear). Reversing the slope of the walls 40 will force the projectile to rotate in the counter clockwise direction. ι The device reaches a steady state or a constant spin rate in a matter of seconds, and this spin rate is accomplished by reducing the conventional length of a prior art projectile without the need for fins extending beyond the diameter of the projectile. The device as described may be machined from a solid piece of aluminum or other light and malleable metal. Slots may be cut into the metal using a router bit. It should be apparent that many modifications may be made to the invention without departing from the spirit and scope of the invention. Therefore, the drawings, and description relating to the use of the invention are presented only for the purposes of illustration and direction.

Claims: What is Claimed 1. A stabilizer for a projectile to be fired from a non-rifled tube of a cannon, comprising: first and second integrally connected and adjacent coaxial cylindrical segments: said first cylindrical segment having means for coaxially connecting the stabilizer to a nose of the projectile and having a diameter smaller than a diameter of the projectile; said second cylindrical segment having a diameter substantially equal to the diameter of the projectile, and a plurality of angled slots circumferentially positioned on the periphery thereof, the slots being defined by opposing spaced apart side walls, said side walls being angled relative to the longitudinal axis of the segments. 2. The stabilizer of claim 1 wherein the slots have a depth defined by the difference between the diameters of the two adjacent segments. 3. The stabilizer of claim 1 wherein the angle between the longitudinal axis of the segments and the side walls of the slots is between about 15 and 75 degrees. 4. The stabilizer of claim 1 wherein an axial length of the first cylindrical segment is longer than the axial length of the second cylindrical segment. 5. The stabilizer of claim 1 wherein six angled slots are equally spaced about the periphery ot the second segment. 6. The stabilizer of claim 5 wherein the angle between the longitudinal axis of the segments and the side walls of the angled slots is about 30 degrees. 7. The stabilizer of claim 1, wherein means for coaxially connecting the stabilizer to a nose of the projectile is a threaded member for engaging a complementary threaded member of the nose. 8. The stabilizer of claim 7 wherein an axial length of the first cylindrical segment is longer than the axial length of the second cylindrical segment. 9. A projectile, to be fired from a non-rifled tube of a cannon, comprising: a nose section having a forward end, a longitudinal axis, and a rearward end, at least a portion of said projectile being cylindrical and having a diameter slightly smaller than the inner diameter of the non-rifled tube; r comprising first and second integrally nd adjacent cylindrical segments, said nose said segments sharing a common longitudinal cylindrical segment having means for coaxially the stabilizer to the rearward end of the nose having a diameter smaller than the diameter of ical section of the nose section; cylindrical segment having a diameter ly equal to the diameter of the nose section, lity of angled slots circumferentially on the periphery thereof, said slots being opposing spaced apart side walls, said side angled relative to the longitudinal axis of the ile of claim 9 wherein the angled slots have a fined by the difference between the diameters of segments. zer of claim 9 wherein an axial length of the l segment is longer than an axial length of the al segment. ile of claim 11 wherein the angle between the s of the segments and the side walls of the about 15 and 75 degrees. 13. The projectile of claim 9 wherein six angled slots are equally spaced about the periphery of the second segment. 14. The projectile of claim 12 wherein the angle between the longitudinal axis of the segments and the angled side walls of the slots is about 30 degrees. 15. The projectile of claim 9, wherein means for coaxially connecting the stabilizer to the nose of the projectile is a threaded member for engaging a complementary threaded member of the nose. 16. The projectile of claim 9 wherein said forward end of the nose is rounded. 17. The projectile of claim 9 where said forward end of the nose is spine shaped. 18. The projectile of claim 9 wherein said cylindrical portion of the nose includes an obturator. 19. A projectile, to be fired from a non-rifled tube of a cannon, comprising: a nose section and a stabilizer coaxially connected thereto, said nose section having a longitudinal axis, a forward end and an aft end, and the largest diameter thereof being slightly smaller in diameter than the inner diameter of the non-rifled tube of the cannon; said stabilizer being cylindrical and having first and second unequal diameters defining at least two coaxial first and second adjacent sections, said first section of said stabilizer being connected to the aft end of the nose of the projectile and having a diameter smaller than the diameter of the largest diameter of the nose section, said second section having a diameter substantially equal to the largest diameter of the nose section, an axial length defining a circumferential periphery and a plurality of angled slots circumferentially spaced apart on the periphery, said slots being defined by opposing spaced apart parallel side walls, said side walls being angled relative to the longitudinal axis. 20. The projectile of claim 19 wherein an axial length of the first cylindrical section of the stabilizer is longer than the axial length of the second cylindrical section, and said plurality of slots are symmetrically positioned on the periphery of the second section.

Inventors: FARINA ANTHONY, GILMAN STEWART, FARINA, ANTHONY, GILMAN, STEWART
Applicants: US ARMY, THE UNITED STATES OF AMERICA
Application year: 1993
Main classification: F42B10
IPC codes: F42B10