US3398684A - Caseless cartridges - Google Patents

Description

Aug. 27, 1968 R; c. KvAvLE 3,398,684

CASELESS CARTRIDGES Filed June 28, 196e I M1@ Z Inventor Fobrf' CvavZe je his Attorney Safes, Patent :O

,ABsTRAmi oF Tina DIscLosURE Vpiojectile houses in its rear end a propellant charge comprised primarily of solidlow explosiveprefe'rably 'in 'the form'of nitrocellulose 'breshaving air'in 'their tsub- `s'tant'iallyl interconectedffin'terstitial spaces, the charge liaviigfa densityless than that of nitrocellulose per se. While -ignition may'be''effected:electrically or otherwise, one mode of ignition contemplated for the cartridge is that eifected by impat withlthe c'ha'rge in a substantially closed chamber sealed bythe projectile.

A copending application, 3L/ 1,242 tiled May 29,

1964, in my name, now Patent 3,283,657 discloses a novel method and means for initiating deagration in a solid low explosiveythe 4required heat beingffrictionallyfgenerated solely by impacting the charge in a substantially closed chamber. This procedure does not rely upon raising temperature by precompression of air about the charge. In another copending application Ser. No. 524,168, tiled Feb. 1, 1966, in my name, there is described a formed low explosive charge of brous nitrocellulose for use in impact ignition devices operable in the novel manner indicated.

A primary object of the present invention is to provide a caseless cartridge carrying within its breech end a solid, stable, impact ignitable charge of low explosive propellant.

A further object is to provide a relatively safe, low cost combination projectile and solid propellant adapted to be operated by impact ignition in a chamber sealed by the projectile itself and its own tiring mechanism. Another object is to provide a light weight projectile having no cartridge case requiring extraction.

To these ends, and in accordance with a feature of the invention, there is contemplated a projectile having its breech end formed with ta charge-containing cavity, the walls and bottom of the cavity being lined with solid low explosive, and a portion of the explosive lining, preferably the bottom wall, being adapted to be impact ignited to initiate deagration and hence gas propulsion of the projectile. A further feature of the invention resides in the provision, in a caseless cartridge of the type indicated, of means such as an external sealing ring or other obturating means, for instance fins, for providing initial resistance to relative movement of the projectile with respect to the ring mechanism, the tins being radially deflectable or deformable in response to pressural build-up in the ring chamber to permit acceleration of the projectile. Since as heretofore noted, ignition of the projectile is to occur in a chamber sealed in part by itself, it is contemplated that a limited air volume surrounding the breech end of the projectile may be predetcrminedly entrapped during ignition by a bolt in the firing chamber and a relatively movable firing pin adapted to enter the projectile cavity to impact its bottom or deagratable lining. The,air volume permitted by the projectile, bolt, and pin is predeterm'1nedly small and hence there is practically no energy wasted in raising its temperature by compression, substantially all kinetic energy of the pin being used to .compress and frictionally crush at least a portion of the propelling charge being Lignited. i I

' The foregoing and other features of the invention, together with novel details in construction, will nowbe more particularly describedin connection with ankillus.- trfative embodiment and with reference to the accompanying drawings thereof, in which; i FIG. 1 is a view inside .elevation of a caseless cartridge 1n accordance with this invention and including a projectile loaded into the firing position of a barrel bore having ring mechanism including a bolt and ring pin; 4

FIG. 2.is adetail Yshowing the tiring pin striking the projectile charge;

.FIG 3 is a view corresponding to FIG. l, the projectile beingl shown in axial section at the instant of impact 1gn1t1on;

FIG. 4 is an enlarged perspective view of the breech end of the projectile of FIGS. 1 and 3 after it has been red and indicating its annular sealing ring as deformed by the barrel rifiing; y

FIG. 5 isa detail view in perspective similarto FIG. 4 but showing another projectile retaining means in the form of groove tting ribs; and

FIG. 6 is a view corresponding to FIG. 5 and showing the retaining ribs as radially deformed in consequence of dellagration of charge.

Referring to FIGS. 1 and 2 a projectile having a cylindrical body 10 may be of any preferred external configuration, its muzzle end generally being pointed and its breech end 12 formed with a cavity 14. This cavity is usually, though not necessarily, cylindrical and coaxial with the body 10. No separate case is needed for the projectile since its cavity 14 is adapted to receive and internally store its charge 16 of solid, low explosive.

The charge 16 may itself be of different low explosive materials and shapes but it preferably lines the bottom and walls of the cavity 14, a portion at the cavity bottom having a raised, reduced area 18 (FIG. 2) to be initially impuacted to effect ignition, for instance by a firing pin 20 moving axially to crush at least a part of the charge and thus frictionally generate the heat for ignition which thereafter causes the entire charge progressively to deflagrate.

As disclosed in the application Serial No. 524,168, cited above, one charge which may be formed Within the body 10 or separately formed as a pellet and then inserted at the time of imminent use, comprises compacted brous nitrocellulose powder. It may include a stabilizer and/or coloring agent, and desirably has a density of less than 1.6 gms. per cc. While the range of propellant density may vary, a density of -about l gram per cc. is usually preferred for funiform, reliable performance. The porosity of such a charge when molded into self-sustaining shape and having entrapped air is believed to facilitate initial ignition by reason of the heat from friction generated during crushing action. Ignition is facilitated by reason of the ribbonlike fibres dening substantially continuous interstitial burning surfaces.

As disclosed in the above-mentioned applications, no detonation is initially produced, but deilagration is -achieved in the solid, low explosive with the expenditure of a relatively small amount of energy by spot heating it electrically or by imp-acting consequent build-up in pressure leading to detonation. This manner of safely and effectively generating propellant gases from the charge is practiced in a closed or substantially closed chamber 24 one end of which is sealed in a barrel 26 by the breech end of the projectile, and the other end of the chamber may be sealed by firing mechanism, for example a bolt 28' and the pin 20 reciprocable therein. For the purpose of holding the projectile against axial displacement in the barrel at the instant of firing pin impact on the charge 16, the breech end 12 preferably is provided with restraining means such as an external sealing ring 30l (FIGS. 1, 3, and 4) adapted to engage the wall of the chamber 24 at the end of bore ritiing 32. As indicated in FIGS. 5 and 6, another form of restraining means may be circumferentially spaced lugs 34 adapted initially to prevent displacement of the projectile as by interference initially with the barrel bore, but upon build-up of pressural 4gases in the chamber 24, be radially deformed or sheared off to permit projectile flight. FIG. 4 indicates how the ring 30 may be slotted as at 36- by the riing 32 'following ignition and completed combustion of the charge 16. Numerous other sealing iins and shrouds are known or may be devised for use with the projectile, or as an integral part thereof, to restrain it during impact ignition and insure that it will receive the benefit of elective obturation.

It is unnecessary that the pin 20l closely t the hollow within the charge 16. The volume of the latter is selected to provide the degree of projectile velocity required. Only a short firing stroke of the pin 20 is needed. The volume of the iiring chamber 24 is mainly determined for a charge size by ixedly positioning the adjacent end of the Sealing bolt. Upon impact of the pin 20 with the igniter portion 18, the initial restraining means 30l or 34, for instance, insure that the projectile will have its charge 16 deagrated. The gases of combustion increase their pressure in the chamber 24 as deiiagration accelerates in the cavity l14. Accordingly, in a very short time the sealing ring 30 or other equivalent can no longer restrain the projectile which then is rapidly propelled from the barrel. Means (not shown) is of course provided for preventing blow-back of the pin 20l and the bolt 28.

Having thus described my invention, what I claim as new and desire to secure by Letters lfate'r1tV of flie'Unitd States is:

1. A caseless cartridge comprising a projectile body having a breech end formed-,with a cavity, and a solid, low explosive propellant, k'lining -at least a portion of the cavity, said explosive being mainly of n itrocelluloseviibres having a density less than that of nitrocellulose Aperfse, the iibres defining substantially. continuous interstitial burning surfaces.

2. A primerless cartridge asset forth in claim 1 wherein the low explosive propellantnis fibrous nitrocellulose powder compacted to a density of about one gram per cc.

3l. A cartridge asset forth `'in claim 2 wherein the lining of low explosive is cylindrical, tubular, and has a diameter less than its axial length, Y

4. A primerless cartridge as sethforth in claim 1 wherein said cavity is coaxial with the projectile body, andthe propellant at the bottom of the cavity has a centrally raised, reduced area adapted to facilitate ignition.

References Cited UNITEDY STATES PATENTSv 5,701 8/1848 Hunt 10Q-49.3 40,092 9/ 1863 Dibble 102--49.3 552,919 1/1896 Maxim 102--101 1,243,253 10/1917 Bush 102-40 2,307,369 1/ 1943 Ferrel. 2,407,264 9/ 1946 Ferrel. 3,311,057 3/1967 Quinlan et al. 102-38 OTHER REFERENCES Military Pyrotechnic Series, Part Three, Properties of Materials used in Pyrotechnic Compositions, U.S. Army Material Command, A.M.C.P. No. 106-187, pp. 218-- 220, October 1963.

ROBERT F. STAHL, Primary Examiner.

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