US1838347A - Propellent powder - Google Patents

Description

Patented Dec. 29, 1931 NET ease

RICHARD GEORGE WOODIBRIDGE, F WILMINGTON, DELAWARE, ASSIGNOR T0 E. I. DU FONT DE NEMOUBS & COMPANY,-OF WILMINGTON, DELAWARE, A CORPORATION OE DELAWARE PBOPELLENT POWDER I No Drawing.

powder.

This application is a continuation in part of my copending applications Serial Nos. I 81,086 and 269,881, filed January 13, 1926, 1.3 and April 13, 1928, respectively.

The practice of adding packets of potassium chloride to the powder charge, principally at night, for the prevention of muzzle flash was known during the World \Var. It is also well known that relatively large additions of potassium chloride or other salts are required when the salt is added in this manner, and that these large additions of such 95 salts seriously disturb the ballistics of the powder charge. There is the further disadvantage that the flashless results are accompanied by large Volumes of white smoke. This is especially true because the amount of potassium chloride or like salt required to suppress muzzle flash when added in packet form may amount to 8 or 10%, and even more, of the weight of the powder charge. In my co'pending application Serial No. ems-e1. filed April 13, 1928, I have shown that flashless results may readily be obtained in a large number of guns with apropellent g powder of the preferred composition Application filed April 22, 1929. Serial No. 357,335.

85 parts nitrocellulose of about 13.15% nitrogen 10 parts dinitrotoluol 5 parts dibutylphthalate 1 part diphenylamine 1 in which there has been incorporated during the process of colloiding and mixing, as little as one part of potassium sulphate.

The flashless results obtained with the above powder are naturally accompanied by a certain amount of white smoke due in part to the potassium sulphate contained in the powder and also to the saltpetre contained in the black powder used in the primer or ignition pad, or both. This amount of smoke is not large or objectionable in the smaller guns, as for example the 3" anti-aircraft, where the Weight of powder charge is about five pounds and the primer contains only about grains of black powder.

Powder of the above type is admirably suited for use in fixed ammunition as flashless results are obtained with relatively little smoke. However, as pointed out in my said co-pending application Serial No. 269,881, when flashless results are obtained in the m/m G. P. F. gun with powder of the above mentioned type, a larger quantity of white smoke is produced. Of this quantity the smaller portion is due to approximately four (4) ounces of potassium sulphate present in the 25 pounds required weight of charge of powder containing 1% of potassium sulphate and the larger portion due to the six ounces 75 of saltpetre contained in the eight ounces of black ignition powder used as an ignition charge to supplement the 21 grain primer.

The ever increasing use of aeroplanes and photography in modern warfare makes it desirable to reduce the amount of smoke to ballistics of the powder charge, and furthermore without yielding excessive smoke which is so objectionable to gunners at any time.

A still further object of my invention is a nitrocellulose propellent powder which, besides being of greatly reduced hygroscopicity, can be dried not only in air but also in hot water in order to more efiectively and expeditiously remove the volatile solvents add ed for the purpose of assisting in the colloiding of the nitrocellulose.

A still further object of my invention is to retain the advantages of my improved propellent powder as described in my copending applications Serial Nos. 81,086 and 269,881, aforesaid, only modifying its composition to the slightest degree in order to produce a powder which in certain guns will not give fiashless results without the use of an additional quantity of a-fiash suppressing salt over and above that incorporated in the powder in an insuliicient amount to give flashlessness.

These objects are accomplished by the following invention, in which I have discovered that a relatively small amount of a flash suppressing salt uniformly incorporated in the colloid is of great value in suppressing muzzle flash, as hereinafter described. By incorporating in the powder an insufficient quantity of a flash suppressing salt the powder will invariably, preferably always, give rise to some muzzle flash. l'n this manner the objection to smoke day time firings is overcome as the smoke is volatilized by. the flash.

However, the incorporation of some-flash suppressing salt, although insuiiicient to suppress muaz'le flash, will insure the uniform distribution of this small amount of the salt throughout the powder gases. 1 have found,

change in velocity and pressure of the powder and at the same time with a minimum amount of smoke.

I have found that potassium salts answer this purpose very satisfactorily, although other flash suppressing salts, particularly the alkali metal salts, may be used as hereinafter more fully described. It will be apparent to those skilled in the art of ordnance that powder of the foregoing type is particularly suited to guns in which the powder is loaded separately in silk bags, because in this way an increment of potassium sulphate or other flash suppressing salt can be added to the charge whenever flashless results are desired.

According to my invention disclosed in copending application Serial No. 269,881, if one part of potassium sulphate is incorporated in the powder flashless results on all rounds would be obtained. This relatively small amount of potassium sulphate required to suppress muzzle flash when the salt is incorporated in the smokeless powder colloid is due to the uniform distribution of the potassium sulphate throughout the powder and. consequently throughout the volume of combustible powder.

I have now found that flashless results may be readily obtained with even smaller quantities of potassium sulphate, one-third to onehalf parts, provided there be subsequently added to the powder charge an additional amount of potassium sulphate in the manner subsequently described herein.

l have found that very desirable results may be obtained by incorporating in the powder approximately one-half of 1% of an alkali salt that is non-hygroscopic up to about 90% relative humidity at atmospheric temperature and that this amount of the salt has no harmful action on the ballistics of the powder.

The following illustrative example will show one embodiment, but this is not be talren in any way as limitation of my invention: Powder of the following compositron 85 parts nitrocellulose of about 13.15% nitrogen content 10 parts dinitrotoluene 5 parts dibutylphthalate 1 part diphenylamine to part of potassium sulphate table of ballistic results and other data given below:

charge itself will give consistently flashless results. Larger quantities, up to sixteen Table of ballistic results in the 155 m/m G: P. F. gun with 95 pound projectile. Primer used, 21 grains with on 8 ounce pad of black sporting powder as base igniter charge Num- Muzzle Me811 meg Composition of powder Added increment of potassium sulphate if; 22:55: ff ggg sure, g gg m lbs/sq. in.

85 pts. N/C of 13.157 nitro en None 3 25lbs.14o 2 4 10 pts. dinitrotoluen g 2344 83 i 5 pts. dibutylphthalate 1 pt. diphenylamine pt. potassium sulphate Same 2 ounces of 5 grain tablets of potassium sulphate 3 26 lbs. 2363 28, 483 1 large contained in silk bag 2 none Same 3 ounces of 5 grain tablets 5 26 lbs. 2356 28, 130 None Same 4 ounces of nitrocellulose colloid containing 50% 5 26 lbs. 2369 29, 040 None or 2 ounces of potassium sulphate 85 pts. N/Q of 13. i5% nitrogen 8 ounces of nitrocell ose, colloid containing 50% 5 26 lbs. 2392 30, 450 3 large 10 pts. dinitrotoluene or 4 ounces of pot ium sulphate 2 none 5 pts. dibutylphthalate 1 pt. diphenylamine tity being put into a silk bag and the bag tied on to the end of the bag loaded charge so that it came next to the projectile. Two ounces of potassium sulphate added in this anner gave two fia-shless rounds out of three while three ounces of the salt gave five flashless rounds out of five.

In the fourth series of firings four ounces of an air dried nitrocellulose colloid containing 50% or two ounces of potassium sul phate were added in a silk bag and five flashless rounds obtained out of five. The smaller amount of potassium sulphate required to suppress muzzle flash when added in the above manner I attribute to the fact that the potassium sulphate is gradually given up to the powder gases during thecombustion of the powder and is more uniformly distributed throughout the volume 'of gases. This method of obtaining more uniform distribution of the potassium sulphate throughout the powder gases comprises a particular feature of my invention.

The last series of firings in the table shows the combination of a powder not containing incorporated potassium sulphate with eight ounces of nitrocellulose colloid containing 50% or four ounces of incorporatedpotassium sulphate. Flashless results were obtained on only three rounds out of five Whereas as shown in co-pending application 269,881 the same amount, four ounces or 1% of potassium sulphate, incorporated in the powder ounces, of the nitrocellulose colloid containing 50% of potassium sulphate failed to give consistently flashless results, which I attribute to the fact that the potassium sulphate does not become uniformly distributed throughout the combustible gases.

As shown by the ballastic results obtained in the third and fourth series of firings shown in the above table. flashless results are obtained with practically no change in the ballistic results of the powder. Therefore, it is unnecessary to make any allowance for change in velocity of the projectile as such allowance would come well within the usual The nitrocellulose is dehydrated with denatured ethyl-alcohol of suitable grade and then colloided in a suitable mixer with the addition of ether. There is added in the ether or directly to the mixer, the dinitrotoluene and the dibutylphthalate. Due to the solvent action of the latter two ingredients, less alcohol and ether are required than is usually the case for nitrocellulose powders not containing these ingredients. The potassium sulphate is uniformly and finely ground in a ball mill or other type of mill to a fineness sufiicient to pass through a wire screen of eighty meshes to the inch. However, I do not limit myself to this fineness. Diphenylamine is usually added as a stabilizer and is usually dissolved in the ether.

The colloid may be pressed either in tubular grains with one or more perforations or in parts nitrocellulose of about 13.15% nitrogen 10 parts dinitrotoluol 5 parts dibutylphthalate 1 part diphenylamine 1A; to part potassium sulphate it should be understood that I do not limit myself to these proportions or to these 1ngredients. For example, the nitrocellulose I may use may be a mixture of the type'soluble in ether-alcohol with the type insoluble in ether-alcohol mixture (two parts ether to one part ethyl alcohol), and of a higher or lower nitrogen content than 13.15%, or it may be entirely of the soluble type, having a nitrogen content between about 12.0 and 12.80%.

The diuitrotoluene may be decreased or in creased, or substituted by other nitro compounds.

The dibutylphthalatemay also be increased or decreased or substituted by other cooling agents which are solvents fornitrocellulose such as those mentioned in m pending application No. 81,086 filed anuary 13, 1926.

The potassium sulphate incorporated in the propellant powder will be in the neighborhood of A to V for the 155 rn/m G. P. E. gun; for other guns having diiierent characteristics it may be greatly in excess of this amount. It should be understood that it is the intention to incorporate in the powder as much potassium sulphate as possible, without obtaining fiashless results, and that the best amount to use for each gun can readily be determined by experimentation.

The potassium sulphate added to the powder chargeis preferably in the .form of tablets,

which prevents dusting that would occur if powdered potassium sulphate were used. The

potassium sulphate may also be contained in a nitrocellulose, cellulose, ester or other film. The silk oi the powder bag may be weighted with the potassium sulphate. However, I prefer to incorporate the potassium sulphate in a nitrocellulose colloid in order that as the colloid gradually burns,- the potassium sulphate will be gradually given up to the powder gases and in this manner there will be secured a more uniform distribution of the tassium sulphate throughout the powd r gases. The colloid containing the potassium sulphate ma be similar in composition to my preferre composition for the propellent powder, as for example 85 parts nitrocellulose of 13.15% nitrogen 10 parts dinitrotoluene 5 parts dibutylphthalate 1 part diphenylamine 50 parts potassium sulphate The above colloid may be manufactured in exactly the same manner as the propellent powder itself, except that it should preferably be air dried. The colloid may be pressed in the form of strips, rolls or tubes with one or more perforations, and cut into convenient grains, which need not be of the same form or thickness as the propellent powder.

powder of the composition described in my.

co-pending applications Serial Nos. 81,086 and 269,881, it should be understood that I do not limit my invention to powder of any particular composition. It will be apparent that I can incorporate in an kind of powder', whether of the nitrocel ulose or nitroglycerine or some other type, potassium sulphate in an insuficient amount to suppress muzzle flash, and that I can add to the powder charge the additional increment of potassium sulphate required to suppress muzzle flash. I

In place of potassium sulphate, either in the propellent powder or the ila'shless increment, or both, I may use some other alkali metal salt such as potassium nitrate, potassium oxalate, potassium chloride, sodium chloride, sodium nitrate, sodium oxalate, etc., but I preferto usethosesalts which are nonhygroscopic up to about relative humidity at atmospheric temperature and also which haveno harmful action on the stability of the powder. It is obvious that in the case of the flashless increment if the salt is added loose or in tablet form it need not be a salt without any action on the stability of the smoke produced by fiashless powders,

particularly the large guns, by providing first, a powder which is not flashless for use in day firings, but which powder contains an insuflicient amount of flash suppressing salt and can be readily made flashless at night by the addition of a very small increment of the same or other flash suppressing salt.

It will therefore be seen from the foregoing that my invention possesses the following advantages among others:

Flashless results are obtained with practicall no changein the ballistic results given by the powder, as the flash suppressing increment is so small as to have no effect on the ballistics of the powder.

Flashless results areobtained at will, either in day or night firings, by the simple expediency of adding to the powder charge a packet of the flash suppressing salt or colloid containing the salt.

These flashless results are obtained with a minimum amount of smoke.

As many apparently'widely different embodiments of this invention may be made without departing from the spirit thereof, it is to be understood that I do not limit myself to the foregoing examples or descriptions except as indicated .in the following patent claims.

I claim;

1. The process of suppressing muzzle flash which comprises incorporating in propellent powder a. small quantity of an alkali metal salt insuficient in itself to eliminate muzzle flash, and subsequently adding to the charge metal salt in quantity sufficient in combination 'th' the alkali metal salt contained in the prop llent powder to suppress muzzle flash.

2. The process of suppressing muzzle flash which comprises incorporating in propellent powder a small quantity of a potassium salt insufficient in itself to eliminate muzzle flash, and subsequently adding to the charge an increment of a potassium salt in quantity suflicient in combination with the potassium salt contained in the propellent powderto sup press muzzle flash.

3. The process of suppressing muzzle flash which comprises incorporating in propellent power a small quantity of potassium sulphate insuflicient in itself to eliminate muzzle flash, and subsequently adding to the charge an increment of a potassium sulfate in quantity sufficient in combination with the potassium sulphate contained in the propellent powder to suppress the muzzle flash.

4. The process of suppressing muzzle flash which comprises incorporating in propellent power a small quantity of an alkali metal salt insuflicie'nt in itself to suppress muzzle flash, and subsequently adding to the propellent powder'charge a cellulose ester collold containing an alkali metal salt.

5. The process of claim 4 in which the alkali metal salt is a potassium salt.

' that already present to suppress muzzle flash.

than 0.5 per cent in combination with a muzan increment of aflash suppressing alkali sulfate in insuficient quantity in itself to suppress muzzle flash in combination with a muzzle flash preventative increment containing potassium sulfate in suficient quantity with 90 9. A propellent powdercomprisin nitrocellulose, a polynitrotoluene, a dialkydphthalate and an alkali metal salt in an amount less zle flash preventative increment containing an alkali metal salt in suflicient quantity with that already present to suppress muzzle flash. 10. A propellent powder comprising nitrocellulose, a polynitrotoluene, a dialkylphthalate and potassium sulfate in an amount less than 0.5 per cent in combination with a muzzle flash preventative increment containing potassium sulfate in sufficient quantity Evitfi that already present to suppress muzzle as i 11. A propellent powder comprising nitrocellulose, dinitrotoluene, 'dibutylphthalate, a stabilizer, and an alkali metal. salt in an amount less than 0.5 per cent in combination with a muzzle flash preventative increment press muzzle flash.

12. A propellent powder comprising nitrocellulose, dinitrotoluene, dibutylphthalate, and potassium sulfate in an amount less than 0.5 per cent in combination with a muzzle flash preventative increment containing potassium sulfate in sulficient quantity with thatv no already present to suppress muzzle flash.

13. A muzzle flash preventative increment comprising a cellulose ester colloid containing incorporatedtherein a muzzle flash preventative alkali metal salt.

14:. The product of claim 13 in which the alkali metal is potassium.

15. The product of claim 13 in which the alkali metal salt is potassium sulfate. 16. A muzzle flash preventative increment comprising a cellulose compound taken from a group consisting of-acellulose ether colloid, a celluloseester colloid, and a cellulose nitrate colloid containing incorporated therein a 1 5 muzzle flash preventative alkali metal salt.

17. The product of claim 16in which the alkali metal is potassium. p

18. The product of claim 16 in which the alkali metal salt is potassium sulfate.

19. A muzzle flash preventative increment comprising a cellulose nitrate colloid containing incorporated therein a muzzle flash preventative alkali metal salt.

20. The product of claim 19 in which the alkali metal is potassium.

21. The product of claim 19 in which the alkali metal salt is potassium sulfate.

22. A muzzle flash preventative increment 10 comprising a cellulose nitrate colloid containing incorporated therein more than 10 per cent of a muzzle flash preventative alkali metal salt.

In testimony whereof, I afiix my signature.

15 RZCHARD GEORGE WOODBRIDGE.