US3033716A - Gas producing charge - Google Patents

Description

United States Patent 3,033,716 GAS PRODUCING CHARGE Ralph F. Preckel, Cumberland, Md., assignor to Hercules Powder Company, Wilmington, DeL, a corporation of Delaware No Drawing. Filed Mar. 7, 1955, Ser. No. 492,802 18 Claims. (Cl. 149-96) This invention relates to the production of smokeless powders and more particularly to the production of smokeless powders having peculiarly desirable ballistics for applications in jet-actuated devices.

It is well known that there is a definite and direct relationship between the pressure at which a smokeless powder propellant burns and its burning rate. This relationship may be mathematically expressed as r=cp or as log r=n log P+log c, where r is the burning rate, P is the pressure at which the burning rate is measured, and c and n are constants characteristic of a given propellant. Thus, when a plot of log r against log P is made for the conventional propellant, a straight line of slope n is obtained showing an increase in burning rate for each increase in pressure. Such a relationship is not disadvantageous in the conventional propellant and in fact is used to advantage in progressive powders where it is highly desirable to generate increased pressures after the projectile or shot charge has begun to move along the barrel. However, this relationship presents a serious problem in formulation of propellants for jet-actuated devices since once the desired operating pressure is reached, totally different considerations obtain.

It is highly desirable, once the operating pressure of a jet-actuated device is reached, that the pressure gen erated by the burning propellant be maintained as nearly constant as possible. Accordingly, if this result is to be attained, the slope n of the line representing the pressure-burning rate relationship of the particular propellant must desirably approach zero in the zone of useful rocket pressure. In the prior art rocket powders, in all of which the slope n has a value of 0.7 or over, any fracturing or slivering of the propellant charge leads to a pressure build-up because of an increase in linear burning rate resulting from the increase in pressure due to the increase in burning surface. The higher the 11 value of the particular powder, the higher will be the pressure rise encountered. Therefore, the results of such a fracturing or slivering vary from a highly undesirable thrust fluctuation with consequent aberration in ballistics, to actual failure of the jet device if, with a propellant of high n value, the pressure build-up is excessive. Even unusual roughness of the charge causes serious changes in burning pressure and burning rate in the presently available rocket propellants with the result that errors of 1% in the nozzle diameter have been found to build up to an aberration of 5% or more in ballistics. Consequently, with the propellants now available, there is very little allowable tolerance in manufacture of charges and nozzles for jet devices. A propellant having a very low n value within the range of useful rocket pressures, however, would allow for considerable tolerances without appreciable deviation from the specified ballistics.

A second serious problem confronting producers of propellants for jet-actuated devices is the diminution of the temperature coefiicient of equilibrium pressure at the desired operating pressure or pressure range. The temperature coefficient of equilibrium pressure is a measure of the pressure variation to be expected on account of temperature variation alone, using a given propellant. It is obtained by firing identical samples of propellant under identical conditions except for changes in temperature and pressure. The coefiicient may be expressed as 3,033,716 Patented May 8, 1962 where AP is the experimental dilference in pressure under conditions of equilibrium burning due to the temperature change At; and 1 is the mean of the low-temperature and high-temperature pressures.

The advantage of having a low-temperature coeflicient of equilibrium pressure is obvious. If the coefiicient is low, the jet-actuated device may be designed for an unusually low range of service pressure over the wide temperature range ordinarily specified for such devices in field use. Since existing propellants generally have temperature coefiicients of equilibrium pressure of about 0.8%/ C. or more, service pressure may change by 100% or more in going from the lowest expected temperature (about -60 C.) to the highest expected temperature (about 50 C.). It is therefore highly desirable to lower the temperature coefficient of equilibrium pressure below that of existing rocket propellants and thereby hold variation in service pressures due to temperature change to a minimum. If the coefiicient could be lowered from 0.8%/ C. to 0.4%/ C. or less, service pressure variation would be diminished by at least one-half.

As a result of the advantages set forth above for a propellant having a low n value and a low temperature coeificient of equilibrium pressure, the combination of those two ballistic characteristics would allow additionally for important economies in the inert weight of jetactuated devices. This is clearly seen if the equation is examined which relates the ratio between the mass of propellant (m) and the mass of the jet device without propellant (M), the gas velocity of the burning propellant (V), and the highest theoretically obtainable velocity of the jet device (V as follows:

With propellants now available, the highest ratio or m/M has been about 1, where mass of propellant and mass of jet device are about equal. If it is possible, by use of a new propellant which will not build up excessive pressures, to decrease M by 10% and increase the amount of propellant to give the same total initial weight, V would be increased by a factor of about 1.15. This would be a 15% improvement.

Therefore, an object of the present invention is the production of propellants for jet-actuated devices which are characterized by such a burning rate-pressure relationship that substantially constant or more nearly constant burning rates are maintained throughout a wide pressure region within the range of useful rocket pressures.

It is a further object of this invention to produce a propellant for jet-actuated devices which is characterized by a lower temperature coeificient of equilibrium pressure which will minimize variation of service pressure due to temperature.

Generally described, the present invention comprises gas-producing compositions which comprise a smokeless powder having uniformly incorporated therein and intimately admixed therewith within each particle thereof a minor amount of at least one material selected from the group consisting of lead, the oxides of lead, the inorganic compounds of lead and the aliphatic compounds of lead, said compositions having a heat of explosion of not more than about 900 calories per gram. The smokeless powders to which these ballistic modifiers are added may be of either single or multiple base. If the smokeless powder to which one or more of the ballistic modifiers is added is a single-base powder, it should preferably comformulations to which the modifiers have not been added, and to show the lack of an appreciable effect of the modifiers on powers having a heat of explosion in excess of about 900 calories per gram. It will be noted that in Z mtroclellluiose i from 5 most instances where the value of n remains high (0.7 or ijfig g' h e i an r ,2; 0.8 or above) between pressures of 300 and 5000 pounds s 0 Pre era y compn e m per square inch, no value is recorded for Pressure region 85% mtrocenulose from 10% to 35% of exploswe of lowest n since such formulations are unsatisfacto liquid ester, and from to 30% of a substantially non- U ml th di t d th d m n volatile nonexplosive plasticizer. In any formulation, h ess lerwlse m ca 6 a g T co p051 0 however, it is critical that the heat of explosion of the ade exam! were Prepare y t C so vent Process ditive system be not greater than about 900 calories per er described. gram. Propellants prepared according to this invention The indicated amounts Of the baulStlC modifiers 1n the which contain a minor amount f th b v -li ted following table were added to a standard rocket powder modifiers and which have a heat of explosion which does composition having the following composition: not exceed about 900 calories per gram, will be characterized by a pressure-burning rate relationship having a Nitrocellulose (13.15% N) 58.5 substantially lower n value and a substantially lower tem- Nitroglycelin 22.5 perature coetficientally of equilibrium pressure. More- Triacetin 5 over, m accordance with the invention disclosed and Ethyl centralite claimed in copending application Serial No. 492,801, filed Dinitrotoluene 2 5 March 7, 1955, it has been discovered that by addition Table I Modifier Tempera- Pressure ture coefii'i- Heat of region of cient of Example explosion, Lowest n lowest 11. pressure in Type Amount, caL/g. p.s.i. region of percent lowest 5.,

percent/"O.

No addition 700 0. 7 0- 8 Lead 0. 5 700 0. 0 1, 300-2, 300 0. 3 do 1. 0 695 0. 2 1, 000-2, 000 0. a do 2. 0 685 0. 2 900-1, 900 0. 4 Lead monoxide O. 5 700 0. 0 700-1, 200 O. 3 Lead oxide (red) 0. 5 700 0. 0 700-1, 200 0. a Lead ermdda 0. 5 700 0. 0 600-1, 200 0. 3 Lead stearate. 0. 1 700 0. 1, 450-2, 250 0. 6 da 0. 2 695 0. 20 1. 400-2, 350 0. a dd 0. 4 690 0. 20 1, 200-2, 200 0. 3 d0 1. 0 675 0. 0 1, 000-1, 500 0. 5 (10 2.0 650 0.0 700-1, 0 0.3 (in 4. 0 600 0. 0 700-1, 300 0. 4 Lead hydroxide 1. 0 695 0. 0 500-1, 000 0. 2 Lead dlacety 1.0 675 0. 0 700-1,000 0. 5 do 2. 0 645 0. 1 500-1, 000 0. 4 Lead molybdate 1. 0 695 0. 1 1, 0004, 700 0. 4 d0 2. 0 685 0. 0 900-1, 500 0. a Lead siilfirin 1. O 695 0. 1 1, 100-1, 700 0. 3 Lead acetate- 1. 0 685 0.1 620-1, 40 0. 5 Lead lii'inloafn 1. 0 685 0. 1 700-1, 600 0. a Basic iead carbonate (PbCO -Pb(OH)2) 1. 0 695 0. 2 700-1, 200 0. 5 Lead 0leate 1. 0 685 0. 2 700-1, 200 0. 5 (in 2. 0 645 0. 3 700-1, 300 0. 5 Lead naphthenate (metal concentration 24%)- 2. 0 680 0. 2 700-1, 300 0. 5 Lead chloride 1. 0 695 0. 3 900-1, 500 0. 4 Lead emomare 1. 0 695 0. 3 500-1, 200 0. 5 Lead iodide 1. 25 690 0. 4 300-1, 500 0. 6 Lead fluoride 1.0 695 0. 4 700-1, 300 0. 5 Lead bromide 1. 0 695 0. 5 1, 300-2, 900 0. 4 Lead diirare 1. 0 695 0. 5 1, 350-2, 400 0. 4 Lead oxalate. 1. 0 695 0. 5 900-2, 000 1. 0 (l0 2. 0 685 0. 3 800-1, 650 0. 5 Lead tartrafe 1. O 690 0. 4 1, 300-1, 700 0. 7 d0 2. 0 675 0. 4 650-1, 500 0. 6 Lead azide 1. 5 695 0. 2 260 0. 7 do 1.5 695 0.2 270 0.5 Lead tetraethyl 2. 5 662 0. 0 500-1, 100 0. 2 do 2. 0 621 0. 3 740-2, 100 0. 5

1 0.2%Zcarbon black added to composition.

of finely divided carbon to the compositions of the present invention, the burning rate of the composition can be Table 2 desirably increased in the pressure region of low It value. It has been found that up to 10% of the various operable E additives may be employed without adversely affecting xafiple Exgffllple g the ballistics of the gas-producing compositions of the invention. However, it is preferred to employ only suf- Nitmcenolose (mm N) 5 58 5 58 5 ficient of the additive to eflect the desired modification gi yc ril 22.8 22.5 22.5 in ballistics. In most cases it has been found that 2% ;,g:, 3;, 3;; of the various additives, based on the weight of the fig g eg 8-5 12.5 3.1 1

S eara e a smokeless powder employed, 1s p Heat olexploslon (cal 700 595 Having now generally described the invention, the 1 0.7 0.7 0.0 following examples are given to illustrate several formugi gg gi fig gj g 'fi lations incorporating varying amounts of the various bal- 7 region o owest 0 (per tP 5 0.4

listic. modifiers, to compare these powders to similar Table 3 Table 6 demonstrates that the desired modifieation in E 1 E 1 ballistics may be obtained in multiple-base powders con- 9. am x mp 6 6 taimng a hquid explosive other than mtroglycerm.

In addition to the previously shown double-base powder examples, the n value and temperature coefficient of equiptii i ei tralig'Ii II 110 110 librium pressure may be substantially lowered in powders o 0 one 00 Leall g of smgle-base formulae, m which the only high potential ff 3 3 3 g ingredient is nitrocellulose, plasticized with small percent- Pressure region of lowest 11 .s.i.)--. 700-1, 200 10 ages of triacetin and ethyl centralite. Temperature coefiicient of pressure in region of lowest 11 (perceut/ O.) 1. 0 0. 4

Table 7 Table 4 Example Example 15 Example Example Example Example 45 46 56 57 58 59 57.0 60.0 Nitrocellulose (12.6% N)-, 90. 0 89. 0 93.0 92. 0 15.0 20. 0 Triacetin 9.0 9.0

1. 0 l. 0 Ethyl centralite-.-. 1. 0 1. 0 7. 0 7.0 6. 4 2.0 1. 0 1. 0 ylp 20. s 11. 0 700 e70 e90 670 Lead stearate (add)- 0. 5 0. 7 0. 45 0. 7 0 4 Heat of explosion (cal. 570 62 Lowest 'n 0.7 0 n (p.s.i.) 2, 500-5,000 2, 000-5, 000 Pressure region of lowest at (p.s.i.) 1, 200-2, 100 Temperature eoelficient Temperature eoefiicient of pressure in region of of pressure in region of lowest 11 (percent/ 0.) 1. 0 0.5 lowest 11 (pereent/ O.).. o. 9 0.2 0. 8 o. 2

Table 5 Example Example Example Example Example Example 47 48 49 50 51 52 Nitrocellulose (13.15% N) 58. 5 58. 5 58.5 58. 5 60. 0 53.0 itroglycerin 22. 5 22. 5 22. 5 22. 5 30. 0 43. 0 Triaoetin--. 18. 0 18. 0 8. 5 8. 5 9. 0 D iethylphthnl are 3. 0 Ethyl r'PnfralitA 1.0 1.0 8.0 8.0 1.0 1.0 Dinitrotoluono 2. 5 2. 5 Lead stearate (add) 0.5 0. 5 2.0 2 0 Magnesium stearate--- 0. 5 Heat of explosion (caL/g.) 745 735 690 690 970 1, 150 Lowest 'll. 0. 7 0. 0 0.2 0. 7 0.5 0. 8 Pressure region of lowest 11 (p.s.i. 1,000- ,000 MOO-2,000 300-900 Temperature eoeflieient of pressure in region of lowest 11 (percent/ O.) i 0.8 0.3 0. 3 0. 9 0.7 2.0

In Table 5, Example 47 demonstrates the inability of mag- *Unplasticized nitrocellulose systems, containing only nesium stearate to produce the desired modification in stabilizer and ballistic modifier, also show a substantial ballistics, While pl 48 P 49 illustrate the P lowering in 11 value and temperature coefiieient of equiablhty Of 1116 modlfiefs 111 the hlghel' P P librium pressure as demonstrated in the following table.

Table 6 Table 8 Example Example Example 53 54 55 Example Example Example Example Nitrocellulose 12.67 N).-. 60 0 60. 0 70. 0 Diethylene gly eol (1511mm 25. o 30. 0 Nitrocellulose (12.6% N)... 99. o 91. 0 94. o 89. o Triethylene glyeol dinitrat 29. 0 55 thyl centrallte 1 0 1.0 1. 0 1. 0 Glycol diaeetate 11. 5 9. 0 Lead stearate (add) 8. 0 Dinitrotoluene. 2. 5 Lead metal pqW r d)-- 5. 0 10.0 Ethyl centralite.. 1 0 1. 0 1. 0 Heat of explosion (cel.lg.)-. 905 670 855 810 Lead, stearate (add) 1. 0 1. 0 LOWOSlS 77.--- 0. 8 0 0. 35 0. 3 Heat of explosion (cal./g.).. 685 740 825 Pressure region of lowest '11, Lowest n o. 7 0.1 0. a p.s.1.) 1, 300-2, 500 650-2, 000 600-2, 000 Pressure region of lowest '11. (p.s.i.)... 900-1, 700 1,100-1, 700 Temperature coefiieient of Temperature coelficient of pressure 60 pressure in region 01 in region of lowest 11 (percent/ 0.). 1. 6 0. 3 0. 4 lowest n (percent/ 0.)... 1. 3 0. 4 0. 5 0. 4

Table 9 Example 65 Example 66 Example 67 Example 68 Nitromllnlosn 58 5 58.5-. 58.5-- Nitroglymrin 27 0 27.0- 27 0 Triaeetin- 8 5 8 5 8.5-- Ethyl centralite.- 2.0.- 2.0.. 2.0.. Ballistic modifier 4.0 lead 2-ethyl- 4.0 lead 2-ethyl- 2.0 lead 2.0 tribasie lead hexoate. hexoate. perchlorate. maleate. Carbon black (added) 0. 0.2. Heat of explosion (caL/g.) 820 807 86 825. Lowest n. -0.38- 10 0.17-- -0.21-.---..---.-- 0.00. Pressure region of lowest 71 (p.s.i.) 300-500 1,050-2,000 9004,3175 1,7002,300 7504,3541. Temperature coefiieient of pressure in region of lowest 11 (percent/O.) 0.30 n 10 0.20 0.00. 0.36.

From the foregoing examples it is evident that although all of the ballistic modifiers disclosed are operable, some are more effective than others in lowering the n value or the temperature coefiicient of equilibrium pressure of a given propellant. This fact allows for a wide choice of modifier based on economic considerations as well as the ballistics desired for a particular application. From the combined viewpoints of eflfectiveness and economy, powdered lead, powdered lead oxides, and lead stearate are preferred.

While the ranges given for the conventional components of the singleor multiple-base powders are not critical as long as the heat of explosion of the powder with the added modifier does not exceed 900 calories per gram, it has been found that powders prepared according to these ranges are more apt to come within this critical calorific requirement.

The compositions of the invention may be prepared by solventless extrusion. In the conventional solventless process, water-wet nitrocellulose and other ingredients are admixed in a Schrader bowl with water. The resulting slurry or paste is dried to 10% water and is colloided and dried between hot colloiding rolls which may be evenspeed or differential-speed rolls as desired. The resulting colloided, dry sheets are then cut into disks or convolutely rolled into carpet rolls. The disks or carpet rolls are then extruded to desired grain size. Flake powder may be formed by suitably shredding the sheet. The resulting grains are normally glazed, usually with graphite, to lower static generation and to improve flowing characteristics.

The compositions of the invention may also be made by the solvent process. In the usual solvent process, the water in hydrated nitrocellulose is first replaced, for example, by treatment with ethyl alcohol. A colloiding solvent such as ether or acetone is then added to the dehydrated nitrocellulose along with additional ingredients and a doughy mass is formed in a suitable mixer such as a sigma blade mixer. This dough is then formed into green grains, usually by extrusion into cords and cutting the cords to the desired length. The green grains are then subjected to solvent removal steps. The greater portion of the solvent is normally removed by passing a warm inert gaseous medium such as air or flue gas over the grains. The remainder of the solvent which can be practically removed is then usually leached out by a water treatment. Water is then removed by an air dry step and the dry grains are normally given a glaze, usually of graphite, to lower static generation and to improve flowing characteristics.

As is well known in the art, colloiding solvent can be removed from powder grains of large diameter and Web only with extreme difliculty. This difiiculty increases as the web thickness is increased. It is, therefore, desirable to prepare grains of the multiple-base formulations of this invention by solventless extrusion or by a suitable casting process. It is preferred to extrude grains up to about or 6 inches in diameter and to cast all larger grains. Casting of the larger grains is preferred because the cost and massive nature of extrusion presses large enough to produce grains of over 5 or 6 inches in diameter become prohibitive.

[In the usual casting process, tiny singleor doublebase powder grains, prepared by either the solvent or solventless techniques, are introduced into a mold together with suitable plasticizers. The plasticizers cause the grains to coalesce into a unitary mass of plastic composition. The preferred casting process is that disclosed in the copending application of Gordon W. McCurdy, Serial No. 28,218, filed May 20, 1948.

The single base formulations given in the examples are preferably made by a conventional solvent process, extruded and cut to the desired granulation. Such a process limits the possible size of the single-base grains to a diameter or web thickness which will allow suflicient removal of the colloiding solvent. Grains of solvent-colloided powder having large diameter and web are, of course, operable and as along as the heat of explosion does not exceed about 900 calories per gram, addition of the disclosed modifiers according to this invention will effect the desired modification in ballistics. It is, of course, well known that the change in ballistics duning storage caused by gradual migration and evaporation of the colloiding solvent is the reason why large grains of solvent-colloided powder are not manufactured. As improved processes and means for solvent removal are devevloped, it will perhaps be possible to produce correspondingly larger grains of solvent-colloided powder which are ballistically stable.

It is not preferred to produce single-base grains by solventless extrusion or by casting because, in order to keep the powder in the single-base category, the plasticizer employed to bring about colloiding and/or consolidation must be of lower potential than the nitrocellulose. The necessary amount of plasticizer, therefore, so lowers the potential that such powders have only a limited application. Nevertheless, incorporation of the disclosed modifiers in single-base grains prepared by solventless extrusion or by casting still results in a low n value and a low temperature coefiicient of equilibrium pressure.

If the gas-producing charges of this invention are made by solventless extrusion, the ballistic modifier or modifiers are preferably added at some time prior to dehydration of the water slurry and the additive system is mixed to a state of homogeneity. The slurry is then dehydrated, the moist mass is rolled into colloided sheets, the sheets are made into rolls and the rolls are extruded in the conventional manner. However, it is often found adavntageous to add the ballistic modifiers during the rolling operation, rather than to the water slurry. The modifiers are then intimately admixed throughout the compsoition by action of the rolls. If the well known Schrader process is employed, the modifiers may be added to the hydrated nitrocellulose in the mixing bowl in any preferred order. A portion of the water is evaporated prior to rolling. The Schrader process is preferred when water-soluble plasticizers are employed.

If the charges of this invention are prepared by solvent extrusion, the ballistic modifier or modifiers are preferably added to the dehydrated nitrocellulose after it has been broken up in a mixer. The modifiers may be introduced with the plasticizer or plasticizers or may be added before or after introduction of the plasticizer as may be desired in the particular formulation.

If the grains are made :by casting, the ballistic modifier is homogeneously incorporated during the preparation of the casting powder as above described.

In order to produce the plateau type ballistics of the invention, the modifiers must be uniformly incorporated with the other ingredients of the composition; that is, the modifiers must be intimately admixed with the other ingredients within each particle of the composition whether the charge is a loose charge of individual grains or consists of a single grain of any desired size. The glazing or coating of a single grain or a plurality of grains in a loose charge will not produce the desired modification in the pressure-burning rate relationships. Thus, powder grains coated or glazed with a lead compound to render them free-flowing are not operable in the invention.

The heat of explosion of an explosive composition may be experimentally determined in the known manner by actually exploding a sample of the substance in a bomb calorimeter under conditions which insure complete combustion of the constituents of the composition, and measuring the heat liberated. However, in the case of smokeless powder compositions which contain at most only small portions of inorganic material, it is usually desirable to determine the heat of explosion by calculation. The calculation of heats of explosion is especially desirable in order to predetermine the calorific value of a proposed composition prior to its formulation. In this calculation, use is made of a simple relation; namely, the heat of explosion per gram of powder is equivalent to the sum of the products of the weight fraction of a given constituent by the contribution to the heat of explosion of the constituent. This contribution of the constituent is for convenience termed the partial calorific potential or the partial heat of explosion, and is usually designated as K. Thus, the heat of explosion of the composition is derived by the equation:

Heat of explosion=2X,K

where X, is the weight fraction of the powder component i.

For compositions consisting principally of carbon, hydrogen, oxygen, and nitrogen, K is quickly and accurately determined according to following equations:

where O, is the number of gram-atoms of oxygen per gram of the powder component i, C; is the number of gram-atoms of carbon per gram of the powder component, i, H, is the number of gram atoms of hydrogen per gram of the powder component, 1', HQ is the heat of combustion at 25 C. and constant volume, and AEf is the heat of formation per gram of the powder components i from its elements.

Partial heats of explosion for inorganic substances, such as the ballistic modifiers of the invention, are not quite so easily calculated but may be determined according to methods disclosed by De Pauw in Z. f. ges. Schiessund Sprengstotfwesen, 32, 11, 36, 60 (1937); or by Hirschfelder and Sherman in Simple Calculation of Thermochemical Properties for Use in Ballistics, 0.S.R.D. Report No. 1300, declassified and issued as PB27421S.

Actually, it is unnecessary to experimentally deter mine the K, values for the various constituents of the smokeless powders in accordance with the invention since tables of the partial heats of explosion for these materials are available as published data. The following is a listing of the K, values of the normally used smokeless powder components and many of the operable ballistic modifiers in accordance with the invention.

Substance (i): Partial heat of explosion (cal/g.)

Acetone --l938 Carbon black 3330 Diamylphthalate -2190 Dibutylphthalate -2055 Diethanol nitramine dinitrate +:1294 Diethylene glycol dinitrate +1030 Diethylphthalate --1746 Dinitrotoluene l'40 Diphenylamine -2684 Diphenylurea +2227 Diphenylurethane -2739 'Ethyl alcohol -1749 Ethyl centralite 2398 Ethyl urethane +1639 Graphite -3377 Lead Lead acetate -282 Lead azide +385 Lead bromide +137 Lead carbonate (basic) 47 1 Lead chloride --151 Lead chromate +977 Lead diacetylacetonate --868 Lead 2-ethylhexoate 11336 Lead fluoride 127 Lead hydroxide 189 10 Substance (i)-Con. Partial heat of explosion (cal./ g.) Lead iodide --91 Lead linoleate 1982 Lead molybdate +403 Lead naphthenate 2048 Lead oleate --2010 Lead oxalate +58 Lead oxide (PbO) +67 Lead oxide (Pb O +139 Lead oxide (PbO +302 Lead stearate -2800 Lead sulfate -15O Lead sulfide --222 Lead tartrate 172 Lead tetraethyl 123l Nitrocellulose, 13.25% N +1041 Nitrocellulose, 13.15% N +1027 Nitrocellulose, 13.00% N +1007 Nitrocellulose, 12.60% N +951 Nitrocellulose, 12.20% N +895 Nitrocellulose, 12.00% N +867 Nitrocellulose, 11.50% N +797 Nitroglycerin +1785 Ni troguanidine ;+720 Triacetin --1284 Water 5 The advantages of the gas-producing compositions of this invention over presently available formulations are readily apparent. The compositions of this invention are characterized by distinguishing properties which have heretofore been found highly desirable but unobtainable, namely, a very low temperature coefficient of equilibrium pressure and a substantially constant burning rate over a wide pressure range within the zone of useful rocket pressures. Although particular emphasis has been placed on the desirability and advantages of the compositions of this invention when applied to jetactuated devices, it is to be understood that these compositions have a general utility in applications where gasproducing charges are desired. They are especially advantageous where substantially constant pressures are desired and where any rapid increase in pressure would be highly undesirable.

This application is a continuation-in-part of my copending application Serial No. 102,427, filed June 30, 1949, now abandoned.

' What I claim and desire to protect by Letters Patent is:

1. A gas-producing composition consisting essentially of a smokeless powder having uniformly incorporated therein and intimately admixed therewith within each particle thereof an amount not exceeding 10% of at least one material selected from the group consisting of lead, the inorganic compounds of lead and the aliphatic compounds of lead, said gas-producing composition having a heat of explosion of not more than 900 calories per gram and having a value of less than 0.7 for the slope n of the line representing the pressure-burning rate relationship.

2. A gas-producing composition consisting essentially of a smokeless powder having uniformly incorporated therein and intimately admixed therewith within each particle thereof an amount not exceeding 10% of lead, said gas-producing composition having a heat of explosion of not more than 900 calories per gram and having a value of less than 0.7 for the slope n of the line representing the pressure-burning rate relationship.

'3. A gas-producing composition consisting essentially of a smokeless powder having uniformly incorporated therein and intimately admixed therewith within each particle thereof an amount not exceeding 10% of lead oxide, said gas-producing composition having a heat of explosion of not more than 900 calories per gram and having a '11 value of less than 0.7 for the slope n of the line representing the pressure-burning rate relationship.

4. A gas-producing composition consisting essentially of a smokeless powder having uniformly incorporated therein and intimately admixed therewith within each particle thereof an amount not exceeding of lead Z-ethyl hexoate, said gas-producing composition having a heat of explosion of not more than 900 calories per gram and having a value of less than 0.7 for the slope n of the line representing the pressure-burning rate relationship.

5. A gas-producing composition consisting essentially of a smokeless powder having uniformly incorporated therein and intimately admixed therewith within each particle thereof an amount not exceeding of a fatty acid salt of lead, said gas-producing composittlon having a heat of explosion of not more than 900 calories per gram and having a value of less than 0.7 for the slope n of the line representing the pressure-burning rate relationship.

6. A gas-producing composition consisting essentially of a smokeless powder having uniformly incorporated therein and intimately admixed therewith within each particle thereof an amount not exceeding 10% of lead stearate, said gas-producing composition having a heat of explosion of not more than 900 calories per gram and having a value of less than 0.7 for the slope n of the line representing the pressure-burning rate relationship.

7. A gas-producing composition consisting essentially of a smokeless powder containing from 85% to 95% of nitrocellulose and having uniformly incorporated therein and intimately admixed therewith within each particle thereof an amount not exceeding 10% of at least one material selected from the group consisting of lead, the inorganic compounds of lead, and the aliphatic compounds of lead, said gas-producing composition having a head of explosion of not more than 900 calories per gram and having a value of less than 0.7 for the slope n of the line representing the pressure-burning rate relationship.

8. A gas-producing composition consisting essentially of a smokeless powder containing from 85% to 95% of nitrocellulose and having uniformly incorporated therein and intimately admixed therewith within each particle thereof an amount not exceeding 10% of lead, said gasproducing composition having a heat of explosion of not more than 900 calories per gram and having a value of less than 0.7 for the slope n of the line representing the pressure-burning rate relationship.

9. A gas-producing composition consisting essentially of a smokeless powder containing from 85 to 95% of nitrocellulose and having uniformly incorporated therein and intimately admixed therewith within each particle thereof an amount not exceeding 10% of lead oxide, said gas-producing composition having a heat of explosion of not more than 900 calories per gram and having a value of less than 0.7 for the slope n of the line representing the pressure-burning rate relationship.

10. A gas-producing composition consisting essentially of a smokeless powder containing from 85% to 95% of nitrocellulose and having uniformly incorporated therein and intimately admixed therewith within each particle thereof an amount not exceeding 10% of lead 2-ethyl hexoate, said gas-producing composition having a heat of explosion of not more than 900 calories per gram and having a value of less than 0.7 for the slope n of the line representing the pressure-burning rate relationship.

11. A gas-producing composition consisting essentially of a smokeless powder containing from 85% to 95% of nitrocellulose and having uniformly incorporated therein and intimately admixed therewith within each particle thereof an amount not exceeding 10% of a fatty acid salt of lead, said gas-producing composition having a 12 heat of explosion of not more than 900 calories per gram and having a value of less than 0.7 for the slope n of the line representing the pressure-burning rate relationship.

12. A gas-producing composition consisting essentially of a smokeless powder containing from to of nitrocellulose and having uniformly incorporated therein and intimately admixed therewith within each particle thereof an amount not exceeding 10% of lead stearate, said gas-producing composition having a heat of explosion of not more than 900 calories per gram and having a value of less than 0.7 for the slope n of the line representing the presure-burning rate relationship.

13. A gas-producing composition, consisting essentially of a smokeless powder containing nitrocellulose and at least one explosive nitric ester and having uniformly incorporated therein and intimately admixed therewith within each particle thereof an amount not exceeding 10% of at least one material selected from the group consisting of lead, the inorganic compounds of lead, and the aliphatic compounds of lead, said gas-producing composition having a heat of explosion of not more than 900 calories per gram and having a value of less than 0.7 for the slope n of the line representing the pressure-burn ing rate relationship.

14. A gas-producing composition consisting essentially of a smokeless powder containing nitrocellulose and at least one explosive nitric ester and having uniformly incorporated therein and intimately admixed therewith within each particle thereof an amount not exceeding 10% of lead, said gas-producing composition having a heat of explosion of not more than 900 calories per gram and having a value of less than 0.7 for the slope n of the line representing the pressure-burning rate relationship.

15. A gas-producing composition consisting essentially of a smokeless powder containing nitrocellulose and at least one explosive nitric ester and having uniformly incorporated therein and intimately admixed therewith within each particle thereof an amount not exceeding 10% of lead oxide, said gas-producing composition having a heat of explosion of not more than 900 calories per gram and having a value of less than 0.7 for the slope n of the line representing the pressure-burning rate relationship.

16. A gas producing composition consisting essentially of a smokeless powder containing nitrocellulose and at least one explosive nitric ester and having uniformly incorporated therein and intimately admixed therewith within each particle thereof an amount not exceeding 10% of lead 2-ethyl hexoate, said gas-producing composition having a heat of explosion of not more than 900 calories per gram and having a value of less than 0.7 for the slope n of the line representing the pressure-burning rate relationship.

17. A gasproducing composition consisting essentially of a smokeless powder containing nitrocellulose and at least one explosive nitric ester and having uniformly incorporated therein and intimately admixed therewith within each particle thereof an amount not exceeding 10% of a fattey acid salt of lead, said gas-producing composition having a heat of explosion of not more than 900 calories per gram and having a value of less than 0.7 for the slope n of the line representing the pressureburning rate relationship.

18. A gas-producing composition consisting essentially of a smokeless power containing nitrocellulose and at least one explosive nitric ester and having uniformly incorporated therein and intimately admixed therewith within each particle thereof an amount not exceeding 10% of lead stearate, said gas-producing composition having a heat of explosion of not more than 900 calories per gram and having a value of less than 0.7 for the 13 slope n of the line representing the pressure-burning rate 2,385,135 relationship. 2,498,388 2,982,638 References Cited in the file of this patent UNITED STATES PATENTS 621,685

1,357,865 Henning Nov. 2, 1920 14 Holmes Sept. 18, 1945 Ball Feb. 21, 1950 Cooley May 2, 1961 FOREIGN PATENTS Great Britain Apr. 14, 1949

Claims (1)

1. A GAS-PRODUCING COMPOSITION CONSISTING ESSENTIALLY OF A SMOKELESS POWDER HAVING UNIFORMLY INCORPORATED THEREIN AND INTIMATELY ADMIXED THEREWITH WITHIN EACH PARTICLE THEREOF AN AMOUNT NOT EXCEEDING 10% OF AT LEAST ONE MATERIAL SELECTED FROM THE GROUP CONSISTING OF LEAD, THE INORGANIC COMPOUNDS OF LEAD AND THE ALIPHATIC COMPOUNDS OF LEAD, SAID GAS-PRODUCING COMPOSITION HAVING A HEAT OF EXPLOSION OF NOT MORE THAN 900 CALORIES PER GRAM AND HAVING A VALUE OF LESS THAN 0.7 FOR THE SLOPE N OF THE LINE REPRESENTING THE PRESSURE-BURNING RATE RELATIONSHIP.