US 3547030 A
Description (OCR text may contain errors)
United States Patent -Patentedv Inventors Appl. No. Filed Assignee ROCKET AND CARTRIDGE CASE THEREFOR 4 Claims, 4 Drawing Figs.
US. Cl 102/38, 102/49.7 Int. Cl F42b 13/28 Field of Search [02/49, 38
References Cited UNITED STATES PATENTS I l/l949 Burney Primary Examiner- Robert F. Stahl Attorney-Edward J. Kelly ABSTRACT: In a rocket-round for a br eechless gun barrel, a tube open at its forward end and closed at its rearward end, a self-propelled rocket in said tube, a booster charge in said tube for initiating flight of said rocket when said tube and barrel are in coaxial alignment, and a malleable metallic sealing ring in the forward end of said tube for forming a gas seal between the forward end of said tube and the rear end of said barrel by extrusion of said malleable ring when deformed by the forward movement of said rocket during initial flight thereof.
ROCKET AND CARTRIDGE CASE THEREFOR This invention is a new and improved rocket ammunition round. a
An object of the invention is to provide a round wherein the rocket is enclosed entirely within a cartridge case, whereby a plurality of the rounds can be automatically and continuously fed into and launched, at high cyclic rates, from a gun such as one disclosed in a copending application, Ser. No. 431,306, filed May 20, 1954 by W. D. Bobco, et al. now, US. Pat. No. 2,965,001.
Another object of the invention is to provide a round which can be fed into and launched from a gun without the delays caused by ramming, extracting and ejecting operations heretofore required. i
Another object of the invention is to provide a round having a booster charge of propellent powder in the. base thereof, and
having a frangible connection between the base cap of the cartridge case and the nozzle plate of the rocket, to delay flight of the rocket until a predetermined gas pressure develops in the booster charge chamber.
Another object of the invention is to provide a round having a cylindrical case whose wall thickness 'is sufiicient to resist the internal pressures developed therein, and whose front end structure cooperates with a seat on the breech end of the aforementioned gun barrel, to insure a gas tight connection therewith.
Another object of the invention is to provide a round wherein aerodynamic stability is increased by reducing the weight of the motor tube and nozzle plate whereby the center of gravity of the entire rocket ismoved'forward.
Another object of the invention is to-provide means within a thin walled rocket motor casing for resisting rotating band pressure. Q
Another object of the invention is to provide a rocket-round structure which is simple in construction, easily loaded and assembled and which will permit and facilitate high cyclic rates, increased range and improved ballistic performance.
Other objects and advantages will be apparent from the following'detailed description and the accompanying drawings, in which: j
FIG. 1 is a longitudinal sectional view of the rocket-round with the rocket in side elevation and showing fragmentary complimentary parts of a gun with which the round is used;
FIG. 2 is a longitudinal sectional 'view of the improvedrocket',
FIG. 3 is a rear end view of the rocket; and
F l0. 4 is a cross-sectional view of the rocket motor, showing the shape of a preferred grain of propellant during production thereof.
In the usual method of launching a rocket the missile is fired from a tube open at both ends and the thrust thereof is imparted only by the expulsion at high velocity rearwardly of the gases from the burning propellant. The present round was invented to be used in a closed breech gun wherein the case of the rocket-round serves as the breech.
in the drawings, wherein for the purpose of illustration is shown one form of the invention, the reference character 5 indicates a cylindrical cartridge case having on its forward open end a collar 6 which reinforces the said end against expansion during the high pressure period of launching. The forward end of the collar 6 is beveled as at 7 to seat within an internal bevel 8 formed on the rear end of a sliding sleeve 9 which is a part of the above mentioned gun. The sleeve 9 is slidably mounted on a rifled barrel 10 by means, not shown, to close the gap between the rear end of barrel l and the forward end of the collar 6, after the tube or case has been transversely moved into firing position in alignment with barrel 10,. A copper ring' 6b is mounted for limited axial translation within a bore in the forward end of collar 6. The inner periphery of the ring is formed as the surfaces of two frustoconical surfaces to define a circular ridge of slightly lesser diameter than the rotating band 31 of the rocket. As the rocket moves forwardly in its case 5, the rotating band contacts the ring 6b and drives it forgas pressure acts on the internal and rear surfaces of ring 6b thereby holding the ring tightly against the rear surfaces of the gun tube and at the same time expanding the ring against the recess in collar 6 to effect additional sealing action against loss of pressure. Each sealing ring is ejected with its cartridge case after firing. A back plate 11, also a part of th gun resists the set back forces on firing.
A base cap 12 is screw-threaded or otherwise secured to the rear end of the case 5 and abuts the back plate 11 when in firing position in the gun. The base cap is centrally bored as at 13 to receive the screw-threaded end of an ignitor tube M having flash openings 15 in its walls. A shoulder 16 on the ignitor tube abuts a boss 17 on the base cap and a screw-threaded nut 18, seated in a counter bore 19 in the base cap, engages the screwthreaded end of the ignitor tube to effect a gas seal. A primer 20 is housed in the rear end of the ignitor tube 14 and axially thereof in a position to be engaged by a firing pin 21 slidable in a bore 22 in the back plate 11. Fire passes from the primer 20 to the ignitor charge 23 in tube 14, and thence through the holes 15 to a booster charge 24. A booster charge found most suitable for this application is the single-perforated propellant coated with Spercent by weight of ethyl centralite and is a progressively burning charge. Such a charge tends to produce gas at an accelerating rate as burning proceeds, thus tending to keep the gas pressure high in the gun barrel as the projectile velocity increases.
A spin stablilized rocket 25 is completely housed within the case's forwardly of charge 24 and comprises a war head 26, a contact fuze 27 and a motor 28. The motor is closed at its front end by a bulkhead 29, FIG. 2, which is grooved at 30 to receive a rotating band 31. The rotating band is located as close as possible to the bulkhead 29 for the purpose of providing resistance to band pressure during travel of the rocket through the gun barrel. The bulkhead is secured to the war head casing by a screw-threaded connection 32 at its forward end and has a rearwardly extending flange 42 to which a light weight motor casing 33 is secured, as by welding or other suitable means. The motor casing is secured at a spaced distance from the rotating band ro form a small circumferential groove 41 for receiving any burs left on the band 31 after engraving by the rifling in the gun barrel 10, which might otherwise impair the aerodynamic characteristics of 'the rocket.
Secured to the rear end of the motor casing by any suitable means, such as screw-threads34 is a light weight nozzle plate 35, lined interiorly by a heat insulator 47, such as asbestos. Centering lugs 49 are circumferentially spaced about the motor casing 28 at its rear end to insure true axial movement of the rocket. Nozzles 36 of steel or other suitable material are formed integral with the nozzle-plate and are provided with inserts 37 of carbon or any other suitable erosion resisting material. The noules are equally and oppositely inclined at such an angle to the longitudinal axis of the rocket as to produce a proper spin in flight due to a tangential component of the thrust engendered by the high-velocity gases issuing therefrom.
Axially aligned with the ignitor tube 14 and screwthreadedly secured to the forward end thereof is a frangible delay'element 38 which is also screw-threadedly secured to the nozzle plate 35, centrally thereof. Intermediately of its securing ends the delay element 38 is. reduced in diameter as at 39, FIG. 2, to a predetermined thickness. Thus the ignitor tube and the delay element hold the rocket in the cartridge case 5, at a spaced distance from the base cap 12 thus providing a chamber 40 of predetermined volume for receiving the booster charge 24. The rocket does not start to move until the gas pressure in the booster chamber has reached about 500 pounds per square inch, at which time: the reduced portion 39 of the frangible delay element 38 will break, thus permitting the rocket to begin its forward motion.
in the present invention a fast burning rocket propellant 43 is desirable because it allows the charge to be cast around a wardly into contact with gun or launcher tube 10. The rising fluted or star shaped core 46 (see FIG. 4) to produce thick webs 44 which are strong enough to prevent crumbling on setback or when ignited. Because the rocket propellant is subjected to extremely high setback forces during launching and also to high centrifugal forces during flight, a propellant of great strength and bondable to the interior of the motor casing 33 is necessary. The material found to be most suitable for this propellant is an outside inhibited composition of Thiokolperchlorate. A quantity of the inhibitor, in this case Thiokol without the oxidizer, is poured into the motor casing 33 which is-rotated' to completely cover the interior thereof by centrifugal action. The excess is drained out andthe casing is heated sufficiently to partially cure the inhibitor adhering to the inside wall thereof and bond it thereto, in a suitable thickness 45, as can be seen by referring to FIGS. 2 and 4. The core 46 coated with a suitable mold release material is then inserted into the casing 33 and the propellant is poured in around the core. The propellant is then cured and the core 46 removed.
A heat resisting layer 48 of asbestos is cemented internally to the rear part of motor casing 33, toresist the heat from the high pressure gases, which tend to increase the diameter thereof and allow the nozzle plate 35 to come out. The nozzle plate screw threads should also be sealed with a suitable cement. A significant feature of the invention is the improved method of igniting the rocket propellant. This is accomplished by eliminating any form of seal from the nozzles and permitting them to remain open, so that the hot gases from the booster charge 24 will quickly ignite the rocket propellant 43.
By this method of igniting the rocket propellant, the motor casing and nozzle plate are not required to withstand extremely high pressures and may be of lighter weight than would be required if a separate igniter were used. With a lighter weight motor casing and nozzle plate the center of gravity of the entire rocket is moved forward, resulting in increased aerodynamic stability and greater range. With a lighter weight motor casing the wall thickness is less and more propellant can be carried, resulting in an increased range for any given caliber and length of motor chamber. As a further result of the reduced rocket weight the peak launching pressure and consequent trunnion reaction for a given nozzle velocity may be reduced.
It is to be understood that the rocketround hereindescribed can be made in any size or caliber desired, but for the purpose of description and illustration, one having a 2.75 caliber rocket is here shown. It is estimated that such a rocket, carrying a payload of 1 pound of high explosive material, will attain a muzzle velocity of 1,200 feet per second when propelled by a progressively expanding booster charge developing 6,000 pounds per square inch.
it is believed that the construction and operation of the invention have been clearly presented and that therefor further discussion is unnecessary.
While we have disclosed a form of the invention presently preferred by us, various changes and modifications will occur to those skilled in the art after a study of the present disclosure. Hence the disclosure is to be taken in an illustrative rather than a limiting sense; and it is our desire and intention to reserve all modifications falling within the scope of the subjoined claims.
1. In a rocket-round for a breechless gun barrel, a tube open at its forward end and closed at its rearward end, a selfpropelled rocket in said tube, a booster charge in said tube for initiating flight of said rocket when said tube and barrel are in coaxial alignment, an a malleable metallic sealing ring in the forward end of said tube for forming a gas seal between the forward end of said tube and the rear end of said barrel by extrusion of said malleable ring when deformed by the forward movement of said rocket during initial flight thereof.
2. In a rocket-round for a breechless gun barrel, a tube open at its forward end and closed at its rearward end, a selffitting said tube, a booster charge in said tube for initiating flight of said rocket means for sealing the ga between the gun barrel and the forward open end of the tu e said means comprising a reinforcing band about the tube end and a seal ing ring housed therein in the path of movement of said rotating band and deformable by pressure of said band to make a gastight seal between the tube and the rear end of said barrel.
3. In a fixed round for a breechless gun barrel having axially slidable means therearound for encircling the breech end of the barrel and the forward end of the round when said round is in coaxial alignment therewith, said round comprising a tube closed at its rear end and open at its forward end, a selfpropelled rocket having a rotating band thereon and slidably fitting said tube, a propelling chargein said tube for initial propulsion of said rocket, and a sealing ring in the forward end of said tube deformable by pressureof said rotating band to seal the gap between the forward end of said tube and the rear end of said barrel when said rocket propellant is initiated.
4. In a fixed round of ammunition for a breechless gun barrel, a tube closed at its rearward end and adapted to be positioned in alignment with and with its open forward end contiguous the rearward end of the barrel, a projectile in said tube and having a driving band fixed thereabout, a propelling charge in said tube between the closed end thereof and said projectile, and a sealing ring mounted in the open end of said tube for limited axial movement and having an inner diameter slightly less than the outer diameter of said band, whereby said ring is moved into sealing contact with the end of the barrel by passage thereinto of said band.