US2429548A - Propellent fuel cartridge - Google Patents

Description

A. M. COHAN PROPELLENT FUEL CARTRIDGE Fiied Sept. 20, 1945 INVENTOR BY 1 7 (I ATTORNEY Patented Oct. 21, 1947 PROPELLENT FUEL CARTRIDGE Alvin M. Cohan, North Bergen, N. 'J., assignor to Atlas Powder Company, Wilmington, DeL, corporation of Delaware Application September 20, 1943,'Serial No 503,095

The present application relates to propellent fuel cartridges.

An object of the present invention is to prepare an improved propellent fuel cartridge, and particularly a cartridge of-superior design which is adapted to perform useful mechanical work as in a prime mover, such as an engine starting mechanism. a

It is a further object of the present invention to provide a cartridge which will avoid the necessity for using special ignition receiving fuels, such as double base smokeless powdery It isanother objectofthe invention to provide improved resistance to-quenching in a propellent fuel cartridge. e

A still further object-of theinvention is to provide a cartridge-Which will permit the use. of simplified fuel charges without loss of efficiency. Other objects/of the invention will appear from the following description.

For a number of years cartridges containing propellent fuel have been employed to do mechanical work, often. through the medium of a piston on which'expanding burning gases from the fuel may work. Such'cartridges have found special utilityfor'use.- in supplying. power for starters for internal combustionengines.

Propellent fuel cartridges whichare to be used to supply power-to actuate a prime mover or otherwise supply useful power should rapidly,

but not explosively, produce a large volume of gas capable of doing work. 'If gas pressure is produced too slowly, efliciency is lost through excessive heat losses to cold mechanical equipment, while if gas pressure is produced explosively, it may break the'lmechanicalequipment before useful work can-bedone. Smokeless powder (colloided nitrocellulose) has been found most satisfactory for. use as a fuel in' cartridges of the present type. This fuel has, however, been difficult to ignite and burn efficiently and. completely under the conditions of low confinement usually obtaining in power producing systems such as engine starters. The sudden gas expansion apparently-interferes with the complete ignition of the fuel. A number of .expedients have been employed to improve the burning characteristics of propellent fuel cartridges. Usually, for best results, it has been found necessary to include some double base powder (.colloided nitrocellulose plus nitroglycerine). Also ithas been found necessary to load cartridges with a succes sion of different sized fuel particles. A-further expedient which has been employed has been to carry a column of flash composition from the v igniting means (which usually lies at the base of the cartridge) up to the front end of the cartridge so as to, ignite the cartridge shell from both ends. All of these methods of improving the burning characteristics of cartridges have 2 Claims. (Cl. 102 -39) 2 some disadvantages. The use of double base powders is considered to be objectionable for cartridges used under some circumstances. The loading of different sized'fuel particles, deck loading .as :it ;is' called, is unduly expensive and troublesome, as is also the expedient of carrying the column of flash composition from the back to thefront end of the cartridges.

Also cartridges of the prior art have not proven as consistent as desirable when a number are used in successioninthe same apparatus. Particularly is this true whenlow ambient temperatures prevail. Under such conditions, the cartridges tend to quench out before'complete combustion takes place. 7

-It has been. found,,according to thepresent invention, that cartridges may be prepared which need contain no double base powders and which may contain a single size powder, and yet be entirely satisfactoryas to powerproduced and resistanc'e to quenching.

Such cartridges. are prepared by coating the insidesurface' of the cartridge shells .with a flash composition. When cartridgesprepared in this manner are ignited, it is found that the igniting .flameistaken up .by the coating of flash composition and spreads,"enveloping the fuel inthe shell, so as to produce moredesirable burning characteristics without the need for deck loading or for double base fuel I Usually the flash composition is most advantageously applied to the surface'of the cartridge through the medium; of a lacquer in which-it'is suspended or dissolved. Such a lacquer bearing a flash composition may be conveniently sprayed into'the cartridge shells to produce the desired coating. Other methods of coating flash composition onto the walls of the cartridge 'mayalso be employed as will'loe evident to those skilled in theart. For example, flash composition may .be dusted ontothe'wallsof'the cartridges after they have beencoated with a tacky material. The benefits of :the present. invention are'ob- "tained in general to the extent that the coating covers the insidesurface of each'cartridge shell. Preferably, however, at least 75% of the inside surface areaiis' coated, andyeven'more preferably the inside surface is' substantially completely coated, although satisfactory results may be obtained in some cases withless extensive coatings. Numerous flash compositions may be used. Y In general, it is found that relatively slow burning flash compositions are more desirable. Flash compositions of the type taught in Young Patent No. 1,935,495 have been found particularly desirable- Asis more fully set forth in that patent, such flashcompositions-comprise anin timate admixture of 'a nitro-aromatic compound and anoxidizing agent. Suitablenitro-aromatic compounds are trinitrotoluene, tetranitroaniline,

tassium, ammonium, barium, and lead, the nitrates of barium, potassium, and lead, and the peroxides of barium and lead. Usuallyit is preferred to employ an oxidizing agent of minimum hygroscopicity, as potassium diohromate'. Among other flash materials which may be employed may be mentioned black powder grains and smokeless powder grains. .Mixturesnf dllfr 4 tively coarse grains of single base colloided nitrocellulose powder, generally represented at 3| in the drawing. This powder was in the form of cylindrical pellets, about 0.325 in. in length and about 0.313 in. in diameter. Following loading,

the cartridge was closed by crimping in cellulose ferent flash compositions also may be employed,

If the flash compositions are to be applied in lacquer form, any suitable lacquer and solvent compatible with the composition may be used. Nitrocellulose in acetone, for example, is desirable for use with tetryI-potassium dichromate mixtures. Nitrocellulose in ether-alcohol mixtures may be successfully used with black powder.

Large sized slow burning particles on fuel are often desirable for use in propellent fuel cartridges, such as, for example, those used for starting engines. In order to successfully employ such difilcultly 'ignitabie and .extinguishable large particles of fuel, complicated deck loading, using" charges or smaller .sizedfnel, has usually been necessary. It has'been found, however, that cartridges of the present invention, having inside shell coatings of tuel ignitlng flash composition, may consist of or straight charges of one large size of'i'uel particles only.

For example, cylindrical of colleided nitrocellulose fuel, as large or larger than .241? diameter by .260" long, may bensed in this ma nor with entirely satisfactory results The invention, however, may also be used to advantage in cartridges containing smaller iuel particles.

A specific embodiment of the'in ention will be described in connection with the drawing which shows a longitudinal section through a starter cartridge of the present invention.

The cartridge comprises a cylindrical laminated paper shell I i, about 3%" longimd about 1 diameter, with a metal :Eerrule t3 ,cnlmped thereon. Eerrule 1.31 has an opening is in its center. Insulating disk 11 lies against I3 and contains a'hole registering with the hole 15 in ferrule [3. Next to disk [1 and spanning registering hole ii in ferrule '13 and insulating disk I! lies metal terminal 1:9. disk 21 covers metal terminal 19 and disk 11. Metal ierrule I3 is electrically connected to electric match head lgniter It bysmatch 23. Terminal 19 also extends "to electric. :matchhead igniter 21'. 'Igniter 21 is of the type described in Pratt Patent No. 2,309,978. Onthe walls of shell H lies flash composition 29.

Flash composition 29 was preparedand applied in the following manner. Nine and onehalf' ounces of scrap nitrocellnlosefilm were dis solved in one gallon of acetone. To ZdQ'cclof the lacquer so produced were added 300 g. or afinely divided admixtm'e composed 50f ifi'ia tenyl and potassium dichrmnate. Then-insulting suspension was sprayed into shell 11., coating substantially the entire. ulterior, where it was pen mitted to dry. Enough lacquer suspension was sprayer. l the shell to supply about 1.5 grams of dry is. doablecontaining the tetryl-potassium czchromate mixture;

Shell llwas then loaded with22 g of. Ida! nitrate wad 33 and was ready for use in the conventional manner by placing it in operative relation with a starter device and igniting it by connecting it by means of ferrule l3 and terminal 1% to a suitable source of electric current. The cartridge prepared as above described was found to produce consistently satisfactory performance. Also, cartridges prepared in this manner were found to be highly resistant to quenchling when used in succession ina single piece of apparatus.

Cartridges or the present invention may, of course, bemodified in manrways without departing from the. present invention. For example, the cartridge shells and other parts may be made of different materials than those described. Also, the end wads may be coated with flash composition as well as the rest of the interior of cartridge shell.. Other flash compositions. and lacquers ,may employed as is outlined above.

Also othersizesand of fuel may be employed. For example, invention may be used to improve the action of deck loaded cartridges and cartridges containing double base powder. Fxnrthermore, different; igniting means than the electric. match headymentioned above can be used. For example. defiagratmg' compositions in various forms, such as globules, tubes, fuse heads, and cocted'wads ignited y park gaps, "bridge. orpercussion caps may be employed with the mesen't invention.

The invention will hefcmrdto be generally applicable wherever is desired to produce apropellent fuel cartridge having improved igniting characteristics.

What is 'claimediis: i

1. A propellant. fuel cartridge comprising an elongated shall, a. coating or flash; composition on the inside surface ofsatd shaman igniting means positioned to ignite said; coating, anda fuel comsinglebase nitrocellulosev granules, said coating having an area of at leastsubstantially of 'theside Emacs; at "the shall so as to produce a fiamefor the encampmentof'the fuel upon actuation cfthe igniting means.

2; A propel-lent fuel according to claim 1111 which theflaslrcumpom'tion an intimate. admixture of. ammo-aromatic compound and a compound selected from the group consisting of chromates and dichromates.

ALVIN Mi.v COHAN.

REFERENGES GI'IED The following references are of record in the file of this patent:

STATES PATENTS Number Name. Date 2,096,698 Lowy Oct. 19, 1937 2,299,466" Coifrnan Oct. 20, 1942 2,207,936 Nardone July 16, 1940 2,362,927 Pratt Nov; 14, I944 FOREIGN PATENTS Number Country Date 275% Great .Britain.... 1909

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