July 14, 1964 ' G. N. TYSON, JR 3,140,582 ROCKET PROPULSION METHOD USING BORON AND NITROGEN COMPOUNDS Filed April 14, 1959

Ger'g .Tyson Jr. INVENTOR.

I", u .12) ATTORNEYS 3,l4,582 Patented July 14,, 1964 2 The nitrogen containing compound and the boron con 3,140,582 taining compound are reacted in such proportions that all ROCKET PROPULSION METHOD USING BORON of the nitrogen and all of the boron react to produce AND NOGEN COMPOUNDS boron nitride, the carbon is released as elemental carbon George N. Tyson, Jr., Claremont, Calif., assignor to Olin Mathieson Chemical Corporation, a corporation of and large volumes of hydrogen gas are produced. Virginia Nitrogen containing compounds which can be employed Filed Apr. 14, 1959, Ser. No. 806,396 as reactants include the saturated hydronitrogens such 20 Claims. (Cl. 60-354) as ammonia, hydrazine, triazane, tetrazane; the unsaturated hydronitrogens such as diimide, triazene, tetrazene, iso This invention relates to a method for producing large 10 tetrazene, ammonium azide, hydrazine azide, and hydra volumes of hot gases in a short period of time, which zoic acid; alkyl hydrazines such as methyl hydrazine, un large volumes of hot gases are useful for many purposes symmetrical dimethyl hydrazine, ethyl hydrazine, unsym including imparting thrust to jet propelled devices such metrical diethyl hydrazine; alkylamines including mixed al as rockets. kylamines such as methylamine, dimethylamine, trimeth Jet propelled devices are essentially of two types: those 15 ylamine, ethylamine, diethylamine, triethylarnine, methyl which depend upon an external source for a portion of ethyl amine, n-propylamine, isopropylamine, di-n-propyl the propellant, and those in which the propellant is en amine, tri-n-propylamine, methyl propyl amine, ethyl prop tirely contained within the device. Such latter devices are ylamine, and the like; alkylene diamines such as ethylene conventionally called pure rockets. This invention will diamine and trimethylene diamine; hydrocyanic acid, alkyl be further described in relation to pure rockets and their 20 nitriles such as acetonitrile and propionitrile, and alkenyl operation. nitriles such as acrylonitrile; alkyl azides such as methyl One of the most important characteristics of a rocket azide, ethyl azide and propyl azide; cyanogens such as propellant system is its performance index or speci?c im cyanogen, isocyanogen and isocyanogen tetrazide; carbon pulse. This is the amount of thrust in pounds that can subnitride; cyanamide, ammonium cyanamide, and alkyl be obtained per pound of propellant consumed per sec 25 cynamides such as methyl cyanamide and ethyl cyan ond. Since the aim is to get as much thrust as possible amide, and dicyandiamide. Mixtures of the above nitro per pound of propellant burned, a high value for the gen containing compounds can also be employed as can speci?c impulse is desirable. their solutions in ammonia or hydrazine. isocyanogen Rocket propellants can be in the form of solids or in tetrazide, CZNM, melting point 89° C., can be prepared, for the form of liquids. Propellants consisting of a single 30 example, by the reaction of isocyanogen tetrabromide in liquid are termed monopropellants and include hydrogen acetone or absolute ethanol with sodium azide, activated peroxide and nitromethane. Propellants involving two by rubbing with a trace of N2H4-H2O and precipitated liquids are termed bipropellants and normally consist of from a little water with acetone, in water at 0° C. with a fuel, such as a hydrocarbon, ethyl alcohol-water or stirring, according to the method described in application ammonia and an oxidizer such as hydrogen peroxide or 35 Serial No. 806,210, of Christoph I. Grundmann et al. ?led liquid oxygen. Other oxidizer fuel combinations include of even date herewith, now US. Patent No. 2,990,412. nitric acid with aniline or furfuryl alcohol. These latter Boron containing compounds which can be employed combinations are termed hypergolic bipropellants since as reactants include boron hydrides such as diborane, tetra they react spontaneously upon admixture. borane, pentaborane-9 (B5H9), dihydropentaborane Hydrazine has also been used as a fuel component in (B5H11), decaborane; alkyl boranes such as trimethyl bipropellant systems in combination with oxidizers such borane, triethylborane and diethyl methyl borane; the as liquid oxygen, hydrogen peroxide, white or red fuming reaction products of diborane with ethylene disclosed in nitric acid, or liquid fluorine. It is spontaneously in?am application Serial No. 540,140, ?led October 12, 1955, mable with nitric acid and with ?uorine. The spec?c of Weilmunester et al.; the reaction products of diborane impulse of hydrazine when burned with liquid oxygen with acetylene disclosed in application Serial No. 514,122, varies from 257 to 264 pound-seconds per pound at 300 45 ?led June 8, 1955 of Stange et al.; the reaction products p.s.i.a. for various fuel-oxygen ratios, the value being of diborane with 3 to 5 carbon atom acetylenes or dienes higher in the presence of excess fuel, and when ?uorine disclosed in application Serial No. 533,944, ?led Septem is used as the oxidizer, the speci?c impulse at 300 p.s.i.a. ber 13, 1955 of Weilmuenster et al.; monoethyltetraborane is about 298 pound-seconds per pound. disclosed in application Serial No. 505,706, ?led May 3, It has been proposed to employ the boron hydrides in 50 1955 of Faust et al.; monoalkyl pentaboranes such as cluding diborane, tetraborane and the pentaboranes as monomethylpentaborane - 9, monoethylpentaborane - 9, fuel components in bipropellant systems wherein liquid mono-n-propylpentabcrane-9 disclosed in application Se oxygen is the oxidizer. Such systems supply high calcu rial No. 497,408, ?led March 28, 1955, now US. Patent lated speci?c impulses of about 290 pound-seconds per No. 3,038,012 of Altwicker et al. and application Serial pound at 300 p.s.i.a. 55 No. 501,742, ?led April 15, 1955 of Chiras et al.; dialkyl Both hydrazine and the boron hydrides are strong re pentaboranes such as diethylpentaborane-9 disclosed in ducing agents, reacting vigorously with a variety of oxi application Serial No. 540,145, ?led October 12, 1955 of dizers. It has now been discovered that, surprisingly, Paustian et al., and now abandoned; the mono- di- and nitrogen containing compounds which are normally con trialkyldecaboranes such as monomethyldecaborane, di sidered to be reducing agents react with boron containing 60 methyldecaboraue, ethyldecaborane, diethyldecaborane, compounds which are also normally considered to be re triethyldecaborane disclosed in application Serial No. ducing agents. Moreover, it has been found that the re 497,407, ?led March 28, 1955, now US. Patent No. actions produce a very high specific impulse, of the order 2,999,117, of Altwicker et al.; reaction products of acet of 300 pound-seconds per pound at 300 p.s.i.a. ylenic hydrocarbons with decaborane and alkyldecabo— Thus large volumes of hot gases are produced accord ranes such as those disclosed in application Serial No. ing to the present invention by reacting a nitrogen con 741,976, ?led June 13, 1958 of Ager, Jr. et al., now taining compound composed only of nitrogen, hydrogen abandoned, and application Serial No. 779,788, ?led De and carbon with a boron containing compound composed cember 11, 1958 of Clark et al., now U.S. Patent No. only of ‘boron, hydrogen and carbon; providing that hydro 3,092,664. Mixtures of the above boron containing com gen is present in at least one of the reactants and providing pounds can also be employed as can solutions of the that carbon is present in at least one of the reactants. solid compounds in the liquid compounds. 3,140,582 9 A The nitrogen containing compounds and the boron con tially opened until reaction is established at which time taining compounds described above react to produce very they are fully opened. After start-up, the flow ratio of ?nely divided solid boron nitride, very ?nely divided car~ nitrogen containing compound to boron containing com bon, and large volumes of hydrogen gas. The following pound is adjusted to be approximately stoichiometric for are representative equationsillustrative of the reactions U1 the reaction of all of the boron in the latter with all of which take place: the nitrogen in the former to form boron nitride, BN. Liquid propellants mostly are reacted in the tempera ture range of 2000° F. to 5500° F. at pressures between 300 and 1500° p.s.i.a. The reaction pressure, as stated previously, can be controlled by the rate of ?ow of the propellants. The nitrogen containing compounds and the boron containing compounds described above react at relatively. high, temperatures of 4500° to 5000.0 F. at these pressures. For rocket engines designed for rela Some of the above nitrogen containing compounds re 15 tively long periods of sustained operating duration, the act spontaneously with the boron containing compounds engine can be cooled, for example by a regenerative cool so that care must be used in their handling. ing system using one of the bipropellant fuel elements or In addition to the extremely high speci?c impulses pro another relatively inert ?uid as the coolant ?owing through duced by the above reactions the use of the above nitrogen a jacket surrounding the reaction chamber. containing compounds and the above boron containing FIGURE 2 of the drawing. shows a modi?cation of compounds as bipropellants for rockets is especially ad FIGURE 1 wherein tank 6 and line 4 are surrounded vantageous since in most instances both of the fuel com by heating coil 12. The modi?cation shown in FIGURE ponents are either normally liquid or can be dissolved 2 permits the use of low melting point solid boranes in a fuel component which is normally liquid. Moreover, such as decaborane in liquid bipropellant systems. tetraborane, which boils at 16° C., can be easily liqui?ed, 25 7 FIGURE 3 of the drawing shows a hybrid liquid-solid and diborane, which boils at -—92.5" C. is much more bipropellant system. In this system, numeral 1' repre easily liqui?ed than, for example, oxygen. sents the reaction chamber and numeral 2’ the nozzle of The operation of a rocket engine employing a bipropel the rocket engine. In chamber 1' there is a cored solid lant consisting of a nitrogen containing compound and a propellant component 13, which can be, for example, deca boron containing compound will be described with refer ‘borane, suspended by holding device 14. The solid pro ence to the accompanying drawing, which depicts sche pellant component can have its ends coated with an in matically in FIGURES 1 and 2 a conventional rocket hibitor. The liquid propellant component, which can be engine employing liquid bipropellants and in FIGURE 3 for example, liquid ammonia, enters through injector 15 an engine employing liquid and solid components of a so as to contact the internal surface of the cored solid bipropellant. propellant and through injectors 16 so as to contact the In FIGURE 1 of the drawing, numeral 1 represents the external surface of the cored solid propellant. reaction chamber and numeral 2. the nozzle of the rocket I claim: engine. Chamber 2 is connected by valved lines 3 and 1. A method for producing a stream of large volumes 4 to vented tanks 5 and 6 respectively which contain re of hot gases which comprises reacting in a con?ned re spectively unsymmetrical dimethyl hydrazine and penta 40 action chamber at a temperature of at least about 4500° borane-9 as the propellants. Tank 7 contains, for ex F. a mixture consisting essentially of a nitrogen con ample, a compressed inert gas such as nitrogen and is taining compound composed only of nitrogen, hydro connected by line 8, containing pressure regulator 9, and gen and carbon containing up to 14 nitrogen atoms and branched, valved lines It? and 11 respectively to tanks 5 up to 9 carbon atoms with a boron containing com and 6. Reaction chamber 1 is generally quite small in pound composed only of boron, hydrogen and carbon comparison with the size of the propellant tanks 5 and 6. containing up to 10 boron atoms and up to 6 carbon The pressure in reaction chamber 1 during the reaction atoms in a reaction zone in a ratio approximately stoichi can be controlled by the rate ofaddition of the propel ometric for the reaction of all of the nitrogen in the lants and is generally in the range of 300-1000 p.s.i.a. nitrogen containing compound with all of the boron in The propellants are forced into reaction chamber 1 against the boron containing compound to form boron nitride, this pressure and the compressed inert gas from tank 7 BN, at least one of the said compounds containing hy is employed to apply pressure to tanks 5 and 6. Instead drogen, and at least one of the said compounds con of a compressed inert gas, pumps can be used for this taining carbon, and exhausting the reaction products. purpose and on larger devices turbopumps can be em 2. The method of claim 1 wherein the nitrogen con ployed driven by turbines supplied with hot gases from a taining compound is unsymmetrical dimethyl hydrazine separate gas generator. and the boron containing compound is pentaborane-9. The propellants enter reaction chamber 1 through an 3. The method of claim 1 wherein the nitrogen con injector which can ‘be of the impinging stream, multiple taining compound is hydrazine and the boron containing hole type, with or without a splash plate, or of the spray compound is methyl decaborane. type. In the former, the propellants are separately in 4. The method of claim 1 wherein the nitrogen con jected through a number of separate holes in such a man taining compound is hydrazine and the boron containing ner that the resulting propellant streams intersect each compound is ethyl decaborane. other and both will break up into small droplets. Spray 5. A method of operating a jet propelled device which type injectors give conical, cylindrical, or other types'of comprises separately supplying to the reaction chamber spray sheets of propellnat ?uids, which intersect and of the device a nitrogen containing compound and a thereby atomize and mix. 65 boron containing compound to provide a reaction mix In some instances, the bipropellant system is hypergolic ture consisting essentially of a nitrogen containing com so that igniting means are not required. To facilitate pound composed only of nitrogen, hydrogen and carbon start-up, however, a glow plug, spark plug or ?ame lance containing up to 14 nitrogen atoms and up to 9 carbon can be provided. Such igniting means are also provided atoms and a boron containing compound comopsed only where the system is not hypergolic. 70 of boron, hydrogen and carbon containing up‘ to 10 Since it is almost impossible to synchronize exactly boron atoms and up to 6 carbon atoms, at least one of the propellant feed of a bipropellant system when start said compounds containing hydrogen, and at least one ing the rocket engine, the nitrogen containing compound of the said compounds containing carbon, reacting the ?ow is advantageously ?rst initiated. The propellant valves nitrogen containing compound with the boron contain can be controlled to operate in sequence and only par 75 ing compound in a ratio approximately stoichiometric for 3,140,582 55 6 the reaction of all of the nitrogen with all of the boron taining compound is hydrazine and the boron containing to form boron nitride, BN, and exhausting the resulting compound is ethyl decaborane. gases from said device so as to impart thrust thereto. 18. A method for producing a stream of large vol 6. The method of claim 5 wherein the nitrogen con umes of hot gases which comprises reacting at a tem taining compound is unsymmetrical dimethyl hydrazine. perature of at least about 4500° F. a mixture consisting 7. The method of claim 5 wherein the nitrogen con essentially of ammonia and a borane selected from the taining compound is ammonia. class consisting of pentaborane-9 and decaborane in a 8. The method of claim 5 wherein the nitrogen con con?ned reaction zone in a ratio approximately stoi taining compound is hydrazine. chiometric for the reaction of all of the nitrogen in 9. The method of claim 5 wherein the nitrogen con 10 the ammonia with all of the boron in the borane to taining compound is unsymmetrical dimethyl hydrazine form boron nitride, BN, and exhausting the reaction and the boron containing compound is pentaborane-9. products. 10. The method of claim 5 wherein the nitrogen con 19. A method for operating a jet propelled device taining compound is hydrazine and the boron containing which comprises separately supplying to the reaction compound is methyl decaborane. 15 chamber of the device liquid ammonia and a borane se 11. The method of claim 5 wherein the nitrogen con lected from the class consisting of pentaborane-9 and taining compound is hydrazine and the boron containing decaborane to provide a reaction mixture consisting es compound is ethyl decaborane. sentially of ammonia and borane, reacting the ammonia 12. A method for producing thrust to a rocket which with the borane in a ratio approximately stoichiometric comprises introducing a bipropellant consisting essential 20 for the reaction of all of the nitrogen in the ammonia ly of a nitrogen containing compound composed only with all of the boron in the borane to form boron nitride, of nitrogen, hydrogen and carbon containing up to 14 BN, and exhausting the resulting gases from said device nitrogen atoms and up to 9 carbon atoms and a boron so as to impart thrust thereto. containing compound composed only of boron, hydrogen 20. A method for producing thrust to a rocket which and carbon containing up to 10 boron atoms and up to 6 25 comprises introducing a bipropellant consisting essen— carbon atoms, at least one of the said compounds con tially of ammonia and a borane selected from the class taining hydrogen, and at least one of the said compounds consisting of pentaborane-9 and decaborane into the containing carbon, into a rocket in contact with each rocket in contact with each other in a reaction zone there other in a reaction zone therein in proportions approxi in in proportions approximately stoichiometric for the re mately stoichiometric for the reaction of all of the nitro action of all of the nitrogen in the ammonia with all gen with all of the boron to form boron nitride, BN, of the boron in the borane to form boron nitride, BN, and reacting the bipropellant in the reaction zone. and reacting the bipropellant in the reaction zone. 13. The method of claim 12 wherein the nitrogen con taining compound is ammonia. References Cited in the ?le of this patent 14. The method of claim 12 wherein the nitrogen con Vernet-Lozet: Interavia, vol. 12, No. 8, Aug. 1957, taining compound is hydrazine. pp. 799-801. 15. The method of claim 12 wherein the nitrogen con Leonard: J.A.R.S., No. 72, December 1947, pp. 10 taining compound is unsymmetrical dimethyl hydrazine and 14. and the boron containing compound is pentaborane-9. Hurd: “Chemistry of the Hydrides,” John Wiley & 16. The method of claim 12 wherein the nitrogen con 40 Sons, NY. (1952), page 84. taining compound is hydrazine and the boron containing American Chemical Society Journal, vol. 75, Jan. 3, compound is methyl decaborane. 1953, p. 756. 17. The method of claim 12 wherein the nitrogen con