April 24, 1962 J. PHILIPSON 3,031,347 SLOW BURNING SOLID COMPOSITE PROPELLANT Filed Feb. 5, 1951 0.40 0.30 IBRNUAr/TISNE,G C a 6 O 8 .0 9 .0 o m CHAMBER PRESSURE, Pc, PSIA INVEN TOR. JOSEPH PHIL IPSO/V Jim Qty“ AT TORNE 3,h3l,347 Patented Apr. 24, 1962 2 In accordance with my invention, I provide a solid pro pellant material which can be made into a solid grain or charge of conventional size and shape, without any unu 3,031,347‘ SLG‘W BURNING SOLEDCOMPOSITE , PROPELLANT J0seph‘Philipson,Temple City, ,Calif., assignor, by mesne assignments, to, Aerojet-General Corporation, Cincin sual con?gurations, and possessed of good physicalcharr asteristics of strength, consistency and the like. I have accomplished my invention by the discovery of particular qualities and characteristics of the components of the propellant. One of the requirements which I have 5 nati, Ohio, a corporation of Ohio Filed'Feb. 5, 1951, Ser. No. 209,507 12 Claims. (Cl. 149—48) This invention relates to jet propulsion and. more par ticularly to solid propellant materials useful in rocket or 10 discovered is that the fuel in the propellant should be one which contains reduced oxygen atoms in the molecule; and by the term “reduced oxygen,” I mean oxygen atoms jet propulsion motors. . ‘ The principal‘ object of my. invention is to provide a solid propellant charge capable of burning at an unusu— included in the molecule whichare linked directly only ally slow burning rate. ponent having reduced oxygen in the molecule decreases to a carbon or a hydrogen atom. The use of a fuel com A further object is to'produce such‘ a slow burning 15 the amount of oxidizer which would otherwise have to be added to the ‘fuel to oxidize the carbon and hydrogen propellant which burns" in a substantially smokeless man atoms to the proper degree. I181‘; A second criterion is that the oxygen in the fuel must A further related object is to produce such a slow burn be the equivalent of at least one-?fth of the weight of ing and smokeless propellant capable of developing a the combined carbon and hydrogen in the fuel. satisfactory speci?c impulse ‘ preferably above 200 lbs. A third, and somewhat related requirement is that the see/lb. when burned at 1000 psi. oxygen in the propellant charge must be su?icient to burn In the operation of certain types of rocket motors, a all of the, carbon in the charge to CO and to convert at solid propellant charge or grain is burned within the least one-third of all the hydrogen in the propellant to chamber to. generate alargevolume of gas under pressure. The gas escapesin the form of a high velocity jet through 25 water. The amount of oxygen cannot be permitted to be substantially less than this critical amount for if less oxy theexhaust nozzle,.producing the reaction force. gen than this be present there will result carbon in the A solid propellant commonly comprises a fuel having discharge which would produceundesirable smoke. mixed with it the oxidizer required. for its combustion. A fourth requirement of the propellant is that no oxid Many solid propellant charges heretofore known burn at a higher rate than isoften desired for long burning charges 30 izer should be used in it which forms any solid particles duringcombustion, for such solid particles would form such as are frequently required in motors for jetassisted the undesirable smoke. This requirement excludes me take-off or for sustainingh?ight. In some cases it might tallic salts as oxidizers. be possible to approximate the performance’ of such a A ?fth requirement is that the oxidizers which are used slow burning charge by use of previously knownpropel lants; but this would normally require resort to some spe 35 must be limited to the group consisting of cellulose nitrate, nitroguanidine, guanidine nitrate, ammonium nitrate, am cial technique such as a substantial lowering of the speci?c monium perchlorate, and mixtures of any of these; with impulse of the propellant-or employing a‘complex grain the added proviso that if ammonium perchlorate be used con?guration. Disadvantages of employing such special as the oxidizer, it cannot be allowed to exceed about 60% techniques are that the resulting intricate structureof- the grain or. charge oftenrequires an unduly greatincrease 40 by Weight of the propellant mixture. Thus, if ammonium perchlorate be selected as the oxidizer, and if more than in the weight of‘the chamber; furthermore, the grain so the 60% oxidizer be desiredfor the propellant, the excess produced is generally structurally weak. must be made up by one or more of the-other of the ?ve One factor by which the burning rate of the propellant named oxidizers. can be a?ected 'is'the coarseness .of the oxidizerparticles. A sixth requirement is that the fuelcomponent of{ the The coarser the’particle of oxidizer the slower will be the propellant must amount to at least, 15% by weight of burning rate. Increasing’ the coarseness of the oxidizer, the ?nished propellant itself. however, should not be allowed to interfere with the cast The fuel component of the propellant should further ability of a cast propellant; and the oxidizer cannot be coarsened to the point where the oxidizer will settle out 50 more be a monomer which polymerizes by addition poly merization, that is, polymerization without the formation in the liquid mixture before polymerization has taken place. . A slow burning propellant according to my invention is de?ned as one havinga burning rate not exceeding 0.15 of an inch'per‘ second at. l000.p.s.i. chamber pressure. Furthermore, when the log burning rate is plotted‘against of any by-products such as water. Examples of unsaturated monomers useful in the prac tice of my invention are unsaturated polyesters, com prising the condensation product of an. alcoholand an - organic carboxylic acid, lower alkyl alkenoates such as methyl acrylate, methyl methacrylate, n-butyl acrylate, diethylene glycol diacrylate, and butanediol-l,3-diacryl the log chamber pressure-the slope n. of the curve, deter mined by the equation 1'=C’Pcn. _ (in. which;;r=the linearpburningrate. in inches/sec. C=a constant ate; lower alkenyl alkenoates such as diallyl maleate, and diallyl fumarate; lower alkenyl alkanoates such as vinyl 60: acetate; lower alkenyl phthalates such as diallyl phthalate; phenyl substituted alkenes such as styrene; as well asrother Pc=the chamber pressure in p.s.i.) shall beequal to or less’ than 0.5. unsaturated compounds, such as diallyl diglycollate and A typical curve for a satisfactory propellant is shown in the graph. According to-my invention, I-provide asmokelesspro ‘ pellant. charge. thatconformstothe above requirementsv by compounding the‘ propellants with- fuels, which are capable of supplying a portion of the oxygen required for the oxidation ofthe carbon and hydrogen, atoms in diethylene glycol bis-(allyl carbonate). 65. The polyesters that may be used in the practice of this invention are the condensation products obtained by re acting a polyhydric alcohol, a saturated dicarboxylic acid and anunsaturated dicarboxylic acid. These resinsihave been described in detail in copending application of Joseph the finished propellantcharge;.andasoxidizer, substances 70 Philipson, Serial No. 200,881, ?led December 14,1950, that yield their. oxygen at arelatively slow rateandfur thermore form no solid oxidation products. now Patent No. 2,941,976,,issued June 21, 1960', and assigned to’ the same assignee as the present application. 3,081,343? 4 01; 13 Some speci?c examples of large numbers of polyester Among the oxidizers which meet these requirements are resins that are suitable for this purpose are as follows: nitrates, perchlorates of non-metallic basic materials, and nitro compounds containing suf?cient oxygen, which form A condensation product made by reacting 4 moles of sebacic acid, one mole of maleic anhydride and 5 moles of propylene glycol. This resin will hereafter be referred no solid oxidation products on combustion. Examples of this class of substances are cellulose nitrate, guanidine nitrate, nitro guanidine, ammonium nitrate, and amonium perchlorate. While ammonium perchlorate is to as resin A. A condensation product made by reacting 7 moles of adipic acid, 3 moles of maleic anhydride and 11 moles of diethylene glycol or ethylene glycol. This resin will here after he referred to as resin B. normally regarded as a fairly slow burning oxidizer for most propellant compositions, its use in propellant com 10 positions heretofore compounded resulted in burning rates faster than the maximum burning rate for slow burning A condensation product formed by reacting 7 moles of adipic acid, 3 moles of maleic anhydride and 12 moles of diethylene glycol. This resin will be referred to hereafter propellants according to the present invention, which by de?nition is 0.15 in./sec. at 1000 p.s.i. chamber pressure. But ammonium perchlorate may be used in limited quan tities or it may be mixed with others of the above-listed oxidizers to produce a propellant having the required slow burning rate. To avoid high burning rates, the amount of as resin C. A condensation product formed by reacting 1 mole of diethylene glycol, 0.9 mole of adipic acid and 0.1 mole maleic anhydride. This resin will be referred to hereafter ammonium perchlorate to be used in any case should not exceed a maximum of about 60% by weight based on the as resin D. A condensation product formed by reacting 1 mole poly propylene glycol (425 molecular weight), 0.9 mole adipic weight of the propellant. If additional oxidizer is then required it should be one of the slower burning oxidizer acid and 0.1 mole maleic anhydride. This resin will be substances mentioned above such as ammonium nitrate, guanidine nitrate or nitroguanidine. referred to hereafter as resin E. A condensation product formed by reacting 1 mole poly propylene glycol (425 molecular weight), 0.8 mole adipic acid and 0.2 mole maleic anhydride. This resin will here after he referred to as resin F. The following formulations set forth examples of pro 25 pellant combinations which fall within the scope of this invention and will burn at the desired rate: A condensation product formed by reacting 1 mole poly ethylene glycol (300 molecular weight), 0.9 mole adipic acid, and 0.1 mole maleic anhydride. Example 1 This resin Will here Percent by Weight after be designated as resin G. A condensation product formed by reacting 1 mole poly ethylene glycol (300 molecular weight), 0.8 mole adipic Ammonium perchlorate acid, and 0.2 mole maleic anhydride. Ammonium nitrate ____ __ This resin will here after be referred to as resin H. A condensation product formed by reacting 8 moles of 35 adipic acid, 2 moles of maleic anhydride and 10.5 moles of diethylene glycol. This resin will hereafter be referred toas Cellulose nitrate _____ __ Fuel: Diethylene glycol bis-(allyl carbonate). _ Methyl acrylate ____________ __ Methyl methaerylate ______ __ This mixture had a burning rate of .115 in./sec. at to as resin I. 1000 p.s.i. A condensation product formed by reacting 8 moles of adipic acid, 2 moles maleic anhydride and 12 moles of 40 diethylene glycol. This reaction will hereafter be referred Example 2 to as resin J. Percent by weight A condensation product formed by reacting 10 moles of diethylene glycol, 4.5 moles adipic acid, 4.5 moles of azelaic acid and 1 mole maleic anhydride. This resin will hereafter be referred to as resin K. Ammonium perchlorate ___________________________________ __ Cellulose nitrate_ _ 40 9 Ammonium nitrate _______________________________________ _. 15 Fuel: The condensation process by which the above polyesters are formed is briefly as follows: 0 The ingredients com Diethylene glycol bis-(allyl carbonate) ______ __ 45 Methyl acrylate _____________________________ __ Methyl methacrylate _______________________ __ 50 5 36 prising the saturated diearboxylic acid, the saturated diol and the unsaturated dicarboxylic acid are mixed together 50 and heated to a temperature of approximately 140° C. until the water formed by the reaction is substantially This mixture had a burning rate of .115 in./sec. at ' 1000 p.s.i. Example 3 driven off. This process is carried out in an atmosphere of inert gas such as nitrogen, carbon dioxide, helium, etc. When the water has been substantially removed the reac 55 tion product may then be subjected to higher temperatures not exceeding 250° C. The preferred temperature range for the ?nal stage of the condensation is between 200 and 230° C. The condensation is continued until the poly ester has reached a desired degree of polymerization as 60 determined either by an acid number or by measuring the viscosity of the polyester. The preferred degree of poly Percent by weight Ammonium perchlorate HCA?GOD! Ammonium nitrate _ Guanidine nitrate Cellulose nitrate Fuel: Diethylene glycol bis-(allyl carbonate) ______ __ 45 } Methyl acrylate _______ __ Methyl methacrylate... merization of the application described above is between 5 and 100. The resulting product is generally a viscous This mixture had a burning rate of .127‘ in./sec. at liquid which when cooled may be stored until it is ready 65 1000 p.s.i. Example 4 to be copolymerized. All of these resins are capable of copolymerizing with a vinyl or diallyl type of compound such as methyl acry Percent by weight late, methyl methacrylate, styrene, vinyl acetate, diethyl ene glycol-bis-(allyl carbonate), diallyl maleate, diallyl 70 fumarate, dialyl diglycollate. The oxidizers contemplated by this invention should be capable of burning without the formation of appreciable solid particles, and they should be characterized by a rela tively slow rate at which they give up their oxygen. 75 Ammonium perchlorate 50 Cellulose nitrate..-" Nitro Qnanidine Fuel: 7 15 Diethylene glycol bis-(allyl carbonate _______ __ 45 50 Methyl methaerylate ________________________ -_ 5 28 3,031,347 6 r-t I c a _ organicperoxides or peresters such as tertiary butyl hy Tins . mlxture ‘had: a; burning, rate of .15 . in./ sec. at 1000 p.s.i.~ droperoxide, l - hydroxycyclohexyl hydroperoxide - 1, methyl ethyl ketone peroxide, benzoyl peroxide, cumene hydroperoxide, lauryl peroxide, methyl amyl ketone per ' Example .-5 5 oxide, etc. Examples of the organic peresters are t-butyl perbenzoate, di-t-butyl. diperphthalate, etc. When a catalyst is used it is generally employed in amounts rang ing between 0.5 %. to 2.0% by weight based on the weight Percent by weight Ammonium'perchlorate ___________________________________ _Ammonium nitrate , __ Guanidine nitrate _________________________________________ __ Cellulose nitrate 50 5 5 ___ Fuel: of the substances to be polymerized. 8 Diethyleue glycol bis-(allyl'carbonate') 45 Methyl acrylate ______ __ 50- Methyl methacrylate... 5 The normal 10 amount usually employed is about 1% by weight. Co polymerization is continued until the sample taken from the polymerized batch ‘shows the desired tensile strength. 32 The propellants according to my invention are capable of developing-thrust for an extended period of time since 15 the rate at which the oxidizers give oif, their oxygen is relatively slow. In addition'the incorporation with the above type oxidizers of fuels with reduced oxygen in an amount equal to or greater than one-?fth the Weight of Percent by Weight the carbon and the hydrogen atoms in the fuel, results in This‘ mixture had a1burning rate of,.1>34 in./sec. at 1000 psi. Example _ 6. Ammonium perchlorate: __________________________________ __ Ammonium nitrate- _______ _., _____________________________ . Cellulose nitrate 20 propellants which burn with a linear rate of not more _than 0.15 in./ sec. Without the presence of reduced oxy 57 . ‘ l5 5.‘ 5 Fuel: Diethylene glycol bis-(allyl carbonate). -. gen in the resins the propellant charges containingv the above oxidizers possibly would not burn at all, and if 45 Methyl aerylate ______ __ _ 50 t Methyl methaerylate__ _ 5 22. 5 they did burn, solid carbon (smoke) would be present in 25 the exhaust gases. My.inventionvhas made possible a series of propellant This mixture had av burning. ratebf .125. in./sec. at 1000 p.s.i. Example 71' charges which are useful where a reasonable amount of thrust is to be appliedv over an extended period of time, such as, for example, in jet assisted take-0E, sustaining 30 rockets or aircraft devices. Percent by weight ‘ Ammonium perchlorate‘ I claim: 1. A solid, slow burning, propellant composition con 5Q Nitro mi'miriine ___ Fuel: sistingof a, cured intimate mixture of a solid, non-metal 15 lic, inorganic oxidizing salt selected from the group con ‘ Resin 0 _____________________________________ .. 4O Styrene _________ __ _. 10 Methylacrylate _____________________________ __ 50 35 35 sisting of ammonium perchlorate, ammonium nitrate, and‘mixtures thereof, in an amount of from about 72% tov 45%-by weight of the total propellantw formulation; Example 8 from about 5% to 22% by Weight of an oxygen rich ad Percent by weight 40 ditive selected from the group, consisting of guanidine nitrate,.nitro guanidine, cellulose nitrate, andmixtures thereof; aud‘yfrom about 23% to, 36% by weight‘ of a Ammonium perchlorate ___________________________________ __ Cellulose nitrate _ Guanidine nitrate __ 50 5 5 Nitm gnanidine ________ __ 5 consistingv of unsaturated polyester resins consisting of 35 45 the. condensation product of saturated polyhydroxy‘ al cohol and polybasic carboxylic acid, a mixture of phenyl Fuel: Rosin G _____________________________________ -_ Styrene _________ __ 40 i Methylacrylate _____________________________ ._ Example 9 Ammonium perchlorate _ Nitro gnanidine __ Fuelz' Resin A _______________ ._ n-Butyl acrylate ______ -. 10 50 substituted lower alkene and an unsaturated, polyester resin consisting of the condensation product of saturated polyhydrox-y alcohol and polybasic carboxylic acid, low 50 or alkyl esters of lower alkenoic acids, diethylene glycol Percent by weight bis-(allyl carbonate), lower alkenyl esters of lower al kenoic acids, lower alkenyl esters of lower alkanoic acids, lower alkenyl phthalates, diallyl diglycollate, and mix 50 15 tures thereof, provided that the amount‘ of ammonium 40 } 35 55 perchlorate present in said propellant composition shall 60 in no event exceed 60% by Weight of the total propellant composition. Example 10 0 Percent by weight Ammonium perchlorate ___________________________________ .. C'ellulosenitrate ‘ __ Guanidinenitrate. ______________________ _. ___- Nine. Qnsmidine Fuel: Resinl‘A; _____________________________________ _. n-Butyl acrylate ____________________________ ._ polymerized resin fuel comprising‘ the addition poly merization product of monomer selected from the group 50 total propellant of'cellulose nitrate, 20% by weight based 5 on the Weight of‘ the total propellant of ammonium nitrate, 32% by weightbased on the weight-of the total propellant of a polymerized fuel comprising 45%- by weight basedv on the weight of the total fuel of‘ cliethylene glycol bis-(allyl‘carbonate), 50% by- Weight based on the weight of the total; fuel of methyl acrylate, and 5% by weight based on the weight of the total fuel of methyl 5 5 40 },_ 2. A slow burning solid propellant composition com prising a cured intimate mixture of about 40% by weight 60 based‘. on the weight of the total propellant of ammonium perchlorate, 8% by weight based‘ on the Weight of the 35 60‘ The. manner in which .the above propellants are formed is by copolymerizing,theingredients shown above. The soluton is polymerized by the use of heat and/or poly m'erization catalysts in~a~~manner that-‘is well known in the art. The" temperatures; in‘ which- copolymcrization takes place is' generally in‘the rangeubetween 20*? C. to methacrylate. . 3. A slow burningsolidipropellant< composition com prising a cured intimate mixture‘ of about‘35% by weight based on the weight of'the total, propellant of ammonium perchlorate, 10% by weight based onthe weight of. the 100° C.. The catalysts which are normally employed are the 75 total propellant of' guanidine nitrate; 10%‘ by Weight 3,031,347 based on the weight of the total propellant of ammonium nitrate, 9% by weight based on the weight of the total propellant of cellulose nitrate, and 36% by weight based on the weight of the total propellant of a polymerized fuel comprising 45% by weight based on the weight of the total fuel of diethylene glycol bis-(allyl carbonate), 8 acid heteropolymerized with a mixture of phenyl sub stituted lower alkene and lower alkyl ester of lower alkenoic acid, provided that the ammonium perchlorate present in said propellant composition shall in no event exceed 60% by weight of the total propellant com position. 9. A solid, slow burning, propellant composition con 50% by weight based on the weight of the total fuel of sisting essentially of a cured intimate mixture of from methyl acrylate and 5% by weight based on the weight about 45% to 72%, by weight, of a solid non-metallic of the total fuel of methyl methacrylate. 4. A slow burning solid propellant composition com 10 inorganic oxidizing salt selected from the group consist ing of ammonium nitrate, ammonium perchlorate, and prising a cured intimate mixture of about 50% by weight mixtures thereof; from about 5% to 22%, by weight, based on the weight of the total propellant of ammonium of a mixture of cellulose nitrate, guanidine nitrate and perchlorate, 7% by weight based on the weight of the nitro guanidine; and from about 23% to 36%, by Weight, total propellant of cellulose nitrate, 15% by weight based on the weight of the total propellant of nitro guanidine, 15 of the total propellant composition of an unsaturated polyester resin consisting of the condensation product 28% by weight of a polymerized fuel comprising 45% of saturated polyhydric alcohol and polybasic carboxylic by weight based on the weight of the total fuel of di acid heteropolymerized with a mixture of phenyl sub ethylene glycol bis-(allyl carbonate), 50% by weight stituted lower alkene and lower alkyl ester of lower al based on the weight of the total fuel of methyl acrylate, and 5% by weight based on the weight of the total fuel 20 kenoic acid, provided that the ammonium perchlorate present in said propellant composition shall in no event of methyl methacrylate. exceed 60% by weight of the total propellant com 5. A slow burning solid propellant composition com position. prising a cured intimate mixture of about 50% by weight 10. A solid, slow burning, propellant composition con based on the weight of the total propellant of ammonium perchlorate, 5% by weight based on the weight of the 25 sisting essentially of a cured intimate mixture of a solid non-metallic inorganic oxidizing salt selected from the total propellant of cellulose nitrate, 5% by weight based group consisting of ammonium nitrate, ammonium per on the weight of the total propellant of guanidine nitrate, chlorate, and mixtures thereof in an amount of from 5% by weight based on the weight of the total propellant about 72% to 45%, by weight; from about 5% to 22%, of nitro guanidine, and 35% by weight based on the weight of the total propellant of a polymerized fuel com 30 by weight of nitro guanidine; and from about 23% to 36%, by weight, of the total propellant composition of prising 50% by weight based on the weight of the total unsaturated polyester resin consisting of the condensa fuel of methylacrylate, 10% by weight based on the tion product of saturated polyhydric alcohol and poly weight of the total fuel of styrene, and 40% by weight basic carboxylic acid heteropolymerized with lower alkyl based on the weight of the total fuel of a condensation product obtained by reacting 7 moles of adipic acid, 3 35 ester of lower alkenoic acid, provided that the am monium perchlorate present in said propellant composi moles of maleic anhydride and 12 moles of diethylene tion shall in no event exceed 60% by weight of the total glycol. . propellant composition. 6. A solid, slow burning, propellant composition con 11. A solid, slow burning, propellant composition con sisting essentially of a cured intimate mixture of from about 45% to 72%, by weight, of solid non-metallic 40 sisting essentially of a cured intimate mixture of a solid non-metallic inorganic oxidizing salt selected from the inorganic oxidizing salt selected from the group consist group consisting of ammonium nitrate, ammonium per ing of ammonium nitrate, ammonium perchlorate, and chlorate, and mixtures thereof in an amount of from mixtures thereof; from about 5% to 22%, by weight, of about 72% to 45%, by weight; fro mabout 5% to 22%, a mixture of guanidine nitrate and cellulose nitrate; and from about 23 % to 36% , by weight, of the total propellant 45 by weight, of a mixture of cellulose nitrate, guanidine nitrate and nitro guanidine; and from about 23% to 36%, composition of the addition polymerization product of by weight, of the total propellant composition of un a mixture of diethylene glycol bis-(allyl carbonate) and saturated polyester resin consisting of the condensation lower alkyl ester of lower alkenoic acid, provided that the ammonium perchlorate present in said propellant product of saturated polyhydric alcohol and polybasic composition shall in no event exceed 60% by weight of 50 carboxylic acid heteropolymerized with lower alkyl ester of lower alkenoic acid, provided that the ammonium the total propellant composition. perchlorate present in said propellant composition shall in 7. A solid, slow burning, propellant composition con no event exceed 60% by weight of the total propellant sisting essentially of a cured intimate mixture of from composition. about 45% to 72%, by weight of a solid non-metallic 12. A solid, slow burning, propellant composition con inorganic oxidizing salt selected from the group consist sisting essentially of a cured intimate mixture of from ing of ammonium nitrate, ammonium perchlorate, and about 45% to 72%, by weight, of solid non-metallic inor mixtures thereof; from about 5% to 22%, by weight, of ganic oxidizing salt selected from the group consisting of a mixture of nitro guanidine and cellulose nitrate; and ammonium nitrate, ammonium perchlorate, and mixtures from about 23% to 36%, by weight, of the total propel~ lant composition of the addition polymerization product 60 thereof; from about 5% to 22%, by weight, of cellulose ni trate; and from about 23% to 36%, by weight, of the total of a mixture of diethylene glycol bis-(allyl carbonate) propellant composition of the addition polymerization and lower alkyl ester of lower alkenoic acid, provided product of a mixture of diethylene glycol bis-(allyl car that the ammonium perchlorate present in said propel bonate) and lower alkyl ester of lower alkenoic acid, lant composition shall in no event exceed 60% by weight 65 provided that the ammonium perchlorate present in said of the total propellant composition. propellant composition shall in no event exceed 60% 8. A solid, slow burning, propellant composition con sisting essentially of a cured intimate mixture of from about 45% to 72%, by weight, of a solid non-metallic inoragnic ovidizing salt selected from the group consist ing of ammonium nitrate, ammonium perchlorate, and 70 mixtures thereof; from about 5% to 22%, by weight, of nitro guanidine; and from about 23% to 36%, by weight, of the total propellant composition of an unsaturated polyester resin consisting of the condensation product of saturated polyhydric alcohol and polybasic carboxylic 75 by weight of the total propellant composition. References Cited in the ?le of this patent UNITED STATES PATENTS 2,155,499 2,165,263 2,187,866 Lawson ______________ __ Apr. 25, 1939 Holm ________________ __ July 11, 1939 Spurlin et a1 ___________ __ Jan. 23, 1940 (Other references on following page) 3,031,347 10 9 UNITED STATES PATENTS 2,255,313 2,388,319 2,416,639 2,443,613 2,443,735 2,472,963 2,479,470 ~ OTHER REFERENCES Fuller _____' ___________ __ Nov. 6, 1945 McLarren: Rocket Engine Fuels, Automotive and Aviation Industries, Aug. 15, 1946, pp. 20-23 incl. and Pearsall ____, _________ __ Feb. 25, 1947 p. 76. Fuller ______________ __ June 22, .1948 Kropa ______________ _- June 22, 1948 Wheeler et 211.: Solid and Liquid Propellants, Journal of The Institute of Fuel, June 1947, No. 114, pp. 137-152 Singleton et a1 _________ .__ June 14, 1949 incl. Ellis ________________ __ Sept. 9, 1941 2,479,828 ' Carr ________________ __ Aug. 16, 1949 Geckler ______________ __ Aug. 23, 1949 248,089 579,057 Great Britain _________ __ Mar. 1, 1926 Great Britain _________ __ July 22, 1946 FOREIGN PATENTS Hackh’s ‘Chemical Dictionary, 3rd edit., The Blakiston Co., Philadelphia, Pa., pp. 178, 575. 10 Bebie: Manual of Explosives, Military Pyrotechnics and Chemical Warfare Agents, The MacMillan Co., NY. (1943), pp. 43, 106-108.
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