US2857258A - Jet propellant - Google Patents

Description

.of the Venturi type.

United States Patent JET PROPELLANT Charles A. Thomas, Dayton, Ohio, assignor to Monsanto Chemical Company, St. Louis, Mo., a corporation of Delaware N Drawing. Application August 22, 1945 Serial No. 612,133

6 Claims. (Cl. 52--.5)

The present invention relates generally to impulse generating compositions and more particularly to compositions suitable for the production of a high velocity gas jet, the reactive impulse of which may be employed to perform useful work such as the propulsion of rocket shells (including anti-aircraft or anti-tank projectiles) or in assisting the take-off of airplanes, gliders, accelerating the movement of wheeled vehicles, etc.

Compositions of the type described herein are generally employed as a gas generating fuel in a chamber referred to herein as a motor and which usually consists of a cylindrical fuel chamber closed at one end and provided at the opposite end with a coaxial orificeor throat The chamber is so constructed as to be. capable of withstanding the high gas pressure which is developed by combustion of the fuel. The products of combustion of the fuel issue as a high velocity gas jet through the throat of the motor, the reactive effect of the gas creating the propelling impulse employed in rocket or jet propulsion.

When motors of the foregoing type are employed in the propulsion of artillery shells such as anti-tank or anti-aircraft shells the motor containing the propellant is generally attached to the base of the shell, the whole assembly being fired from a smooth-bore tube or rack. For use in assisting the take off of aircraft or accelerating the motion of vehicles generally, one or more of the motors may be mounted upon the plane or vehicle in such a way that the impulse created by the high velocity gas jet is transmitted directly to the aircraft or vehicle.

The present compositions are adaptable to a wide variety of purposes, depending upon the rapidity and conditions under which they are burned. They may be adapted to the propulsion of artillery shells, in which case the burning time is relatively short. They may also be adapted for assisting the take-off of airplanes either from land or water, in which case the burning time is considerably lengthened. In other cases they may be used to assist in starting or accelerating the motion of vehicles such as railroad trains, in which case the burning time is still somewhat longer. By a suitable variation in the composition, as will be hereinafter more fully described, impulse generating compositions suitable for these various purposes may be produced.

In determining the suitability of any gas generating composition for impulse, rocket or jet propulsion purposes, the most important properties of the fuel to be considered are: (1) its specific impulse, (2) the reproducibility of its burning properties, and (3) the relation between its rate of burning, the pressure and the temperature. The specific impulse is the total impulse (i. e., force-time integral) imparted to the motor per unit weight of propellant consumed and provides a measure of the performance to be expected from a motor or rocket using the fuel in question. Reproducibility is indispensable if power and freedom from bursts are to be obtained; while a low depedence of rate of burning on pressure and preignition temperature greatly sim- 2 plifies motor design, increases the range of climatic conditions under which the device is usable and decreases the hazards which arise from small variations in the property of the fuel.

The foregoing critical properties are all fundamentally related to the rate of burning of the fuel and this, in turn is known to be dependent upon (1) the burning area of the fuel, (2) the pressure within the motor and (3) the pre-ignition temperature of the fuel. Considering firstly the burning area factor, it is known that the rate of burning will vary if the burning area of the fuel as it is consumed is either decreasing (called a degressive or regressive burning area) or increasing (called a progressive burning area).- The effect of this factor may be minimized to a considerable extent by forming the composition into'bodies (called gr-ains) having geometric forms so designed and inhibited as to insure a substantially constant burningarea as the fuel is consumed.

Considering now the efiect of pressure on the burning rate, from theoretical considerations, it will be apparent that when the fuel is ignited, the pressure within the motor chamber rises from atmospheric pressure to a higher pressure at a steady state. Inasmuch as the pressure existing within the rocket motor greatly affects the burning rate, erraticbehavior likely to result in explosions of the fuel chamber may be anticipated if the fuel is characterized by a pronounced depedence of burning rate upon pressure. Considering the burning phenomena in greater details, after ignition of the fuel, the pressure within the motor chamber will rise until the rate of gas formation within the chamber equals thev rate of efilux, at which point a steady condition will be attained. Since the rate of gaseous combustion prod ucts is proportional to the burning area of the grain (A and also to some power of the pressure (P and since the rate of efilux is proportional to the pressure P and to the area of the orifice or throat (A a steady state will exist when:

K A P =K A P the steady state pressure is therefore given by:

A z ia) since P A and A, are all readily measurable quantities,

v it is possible to plot log P against log (A /A Such a plot will describe a straight line of the slope-intercept form, the slope of the line being the exponent 1/ (l-n), from which the value of the exponential constant n may be determined.

In the case of actual propellants, some deviation from the so-called burning law may be observed. However, the smaller the average deviation of the observed pressures from a smooth plot of pressure against A /A the more highly reproducible will be the internal ballistics 0f the fuel. Moreover, the closer the value of n approaches zero, the less sensitive'does the system become to small variations in A and A i. e., the less rapidly will the pressure vary with small variations'in the condi tlons of burning such as the grain area, obstructions in r the throat of the motor, etc. Conversely, the closer the .value of it approaches unit,.the,more, sensitive does the system become to variations in grain area and throat area, and in the limiting case where n becomes unity, it will beapparent that the" pressurevariesas the infinite power ofthe Agyto At ratio.-l r

Thus the swcalled burning: lawg and particularly the value of n, the exponential constant, are of fundamental importance 1 in? the selection of a rocket propellant and inEthe design-of' the rocket motorya fuel-thabdeviates only slightly from the so-called' burning, law andthat pus-- sesses-a W" value of: n will-be characterized by a' high: reproducibilityof chamber pressures,-th'ei'eby permitting: the-use of lighter chamberwallssand generally of' a' lower factor of safety inmotor designs 'lhlrningmow to the-effect of temperature on the burning: rate, a low dependence of the burning rate on' the temperature of the fuel prior to ignition (referred to as ambient or pr'e-ignition temperature) is of the ut mostl importance in rocket design, for several reasons. In the first.place,-if thefuel has a large temperature co'- eflicient of -pressure-(it e., rate of:change.0f pressure with respect to pre-ignition temperature, in a given motor using: a grainrofgiven-area A a motorthat is safe to meat low pre-ignitiontemperatures may burst if used; for example under hotdesert conditions. On the other hand, if the motor is designecl-for useat highpreignition temperatures, then it is unnecessarily massive for use under moderate or low temperature conditions; Furthermore, .ifthe pressure developed'in the rocket motor falls: below a certain-threshold value, the propellant tends to burn incompletely; Therefore, if the fuelis characten' izedby alarge temperature, coefiicient, the possibility is increased of burn-outs" at low pre-ignition temperatures; aswell as fblow-outs at high-pre-ignition temperatures. Finally, a fuel with a large temperature coefficient will be characterized by an undesirably high degree of dispersion at low pre-ignition temperatures, and also by variable ballistics (changes in range) with variations in: the temperature of the fuel-prior to ignition.

Considering the temperature factor somewhat more closely, ithas been found that if the rate of burningis measured at different ambient temperatures but at the-- same maximum pressure, then the rate of change of burning with temperatureisrelativeIy small in the case of practically, all existing: rocket fuels. Unfortunately, how ever, in actual use,'the only factor capable of being main tained substantially constantris the. ratio: A /A i. e., the grain area and the throat area. In other words, the maximum pressure developed inthe motor chamber is' not a constant butrvaries with the ambient temperature. But as previously, explained, in-the-case of fuels-having a large value of: n, changes. inpressure profoundly affect the rate of'buruing. Accordingly, thetemperature effect is intimately related to. thepressurevefiect.

The temperature effect discussed above is more pre cisely defined by the relation:

value of the exponential constant 11,. the smaller will bethetemperature coefficient of" the rate of burning at a constant A' to A ratio. Conversely, if n approaches unity, the temperature coefficient of the. burning rate From the foregoing, it will be apparent that a small value of the exponential constant n in the so-called burnand 1 is the'dilference'betweenthesquare-and cube-of a very large numhenlfor instance,.the difference between t (200 and- (200) which intthis case amounts to 7,960,000.- Small numerical diifere'ncesin n values of impulse fuels are, accordingly,.of great significance, not only. in respectto' reproducibility at a substantially constant preignition temperature, but also withrespect to uniformity of action under; varying" pre ignition temperatures.

Inthe preceding paragraphs, the importance-of (1 )a smallzdeviation from the burning-l law, (2) a small 11 value, and (3) aloW-temperature-coetficient, have been discussed. In addition tothesefactors itis also, desirable Y to employ a propellantcharacterizedby. as high a density as possible, inasmuch asahighdensity permits-the use of. a smaller firing chamber, thereby making itpo ssibleto decreasei the'sizeand mass of the motor and therefore to improve thetballistics of the'motor.

From-the'above analysis it will;be apparent that the design ofthe impulse fuehpresents an exceedingly complex problem, the solution of which is-complicated bythe l fact that the properties of a gas generating composition under atmospheric conditionsafford practically no indication ofthe properties of such composition. when burned under the conditions obtaining in an impulsemotore In short, the design-0f apropellant fuel for jet propulsion at the present:: time is almostentirely an empirical problem, that requires. the mostpainstaking and protractedexperimentation. A

Broadly; speaking, the object= ofthe present invention isto'provid'e anew andimproved gas generating compositionsuitable for. rocket purposes.

A more particular object is the provision of a novel impulse propellant characterized by z (1) A burning rate which deviates only'slightly from the so-c'alled burning law";

(2) A low value of the exp'onnentialconstant ll in the burning 1 law;

(3-) A" low temperature coefficient of pressure change when: afuel of given'grain area is fired'in'a given'rnotor at various pre-ignitiontemperatures. A further object'isap'ropellant possessing the follow ing additional characteristicsz (a) A sufficiently high specific impulse; (b)- Relatively constant external ballistics;

, (c) A burning-rate whichrnay be made high or low at will;

(d) Adaptability to. the production of grains of high and low burning times;

(a) High mechanical strength and freedom from distortion under stress; (I) High loading-density;

(g) Moderate motor. chamber requirements; (h) Adaptability to molding to close dimensional tolerances without mechanical finishing operations;

(i) Ready. availability. of raw materials,

(j).- Relative simplicity of the equipment required for fabrication.

Other objects and advantages will become apparent as the invention is hereinafter more particularly described.

As the result of an extended investigation it has been found that the objects set forth above may be obtained by a novel type of propellant consisting of a particulate gas generating composition compacted in the presence of a binder comprising a chlorinated polyphenyl body. More particularly, the gas generating composition herein provided consists essentially of two components; namely, (1) a particulate non-plastic gas generating composition and (2) a binder comprising a resinous chlorinated diphenyl or terphenyl with or without one or more resinous bodies. Propellants of the present type differ fundamentally from previous fuels of the smokeless powder (ballistite) type wherein the plastic component of the composition was a major constituent. In the composite fuels of the present invention the solid non-plastic gas generating component constitutes generally as high as 90-95% of the composition, the plastic component being employed in relatively small proportions which serves not only asa binder but as a modifier of the burning characteristics of the gas generating component.

I. THE GAS GENERATING COMPONENT 'The gas generating component in accordance with the present invention consists of a mixture of finely divided solid materials which are capable of interaction under the influence of heat to produce a-large volume of gaseous reaction products. Mixtures of this type usually consists of an oxidizing substance and an oxidizable substance. The oxidizing substance may comprise one or more solid inorganic oxidizing agents such as the nitrates, for example, sodium nitrate, potassium nitrate, barium nitrate, ammonium nitrate and the like. The oxidizable substance desirably comprises one or more solid organic nitro compounds or their salts, such as the sodium or preferably the ammonium salts of nitro phenols (for example, ammonium picrate) or one or more solid nitramines (for example, nitroguanidine).

In general, the oxidizable substance and the oxidizing substance may be employed in a wide range of proportions, depending on the particular use to which the ultimate fuel is to be put. In some instances, it may be desirable to use the components in the proportions required for oxygen balance for the production of CO and H (i. e., zero oxygen balance); in the case of ammonium picrate=sodium nitrate mixtures this result is obtained with a weight ratio of 52.5 to 47.5, respectively. However, for other purposes, a different specific impulse or a different burning rate may be desirable, in which case the relative proportions of components may be considerably altered with a View to modifying one or more properties of the fuel. Thus, for aircraft take-off purposes or for other uses where a low rate of burning is desirable, a -90 sodium nitrate=ammonium picrate composition may be satisfactory, whereas for anti-aircraft rockets or other purposes where a high rate of burning is desirable a 50-50 mixture of these same components may be preferable.

Generally speaking, in the case of ammonium picratepot'assium nitrate mixtures, it is undesirable to employ in excess of about 55% potassium nitrate, since a further increase in this component increases the solid reaction product (potassium carbonate) at the expense of the gaseous products, thereby cutting down the power of the propellant. A high specific impulse will be obtained with mixtures containing from about 10% to about 55% potassium nitrate. A high rate of burning will be obtained with a composition containing ammonium picrate 45%, potassium nitrate 55%.

Certain general principles governing the relation of composition to impulse are reasonably clear. Any change in composition which lowers the proportion of solid reaction product tends to increase the specific impulse, in any case more'than compensating for an accompanying decrease in heat of reaction. Thus, an increase in the proportion of ammonium picrate in a mixture with potassium nitrate beyond the 48.5% required for a zero oxygen balance leads to a decrease in the predicted heat of ,This general observation serves as auseful guide in devising new proportions of ingredients.

In some cases, it may be desirable to incorporate small amounts of other materials in the gas generating composition, in order to modify one or more characteristics of the molding powder or of the finished propellant. Thus, a small amount of a readily combustible material such as aluminum powder, charcoal, sulfur and the like, may

' be added for the purpose of modifying the burning propphenol-formaldehyde or urea-formaldehyde resins.

. include a solvent'for, these resins.

erties of the fuel.

II. THE BINDER The chlorinated polyphenyl products mentioned above, which may be used as binders in accordance with the present invention, may comprise the chlorinated diphenyls or chlorinated terphenyls and mixtures thereof. Chlorinated polyphenyls suitable as binders for the production of the composite gas generating body may be prepared as described by Jenkins et al., in United States Patent 1,892,400. When diphenyl, alone, is chlorinated, the chlorine content should be at least 54% by weight and may be as high as 64% or 65% by weight. These products are preferably used in the non-crystalline form as described in the above patent; however, some crystalline phase resulting from a somewhat higher degree of chlorination may also be present. As described in the above mentioned Jenkins et al. patent some higher boiling aromatic hydrocarbons related to diphenyl (and comprising the terphenyls) may also be present in the material undergoing chlorination. As a matter of fact, for the present purpose, the binder may comprise wholly the chlorinated terphenyl fraction, but generally it appearsdesirable to employ a mixture of diphenyl and terphenyl as the hydrocarbonwhich is chlorinated, to the extent of between 40% and 60% or 65% by weight of chlorine. For the purpose of the present specification and claims, the chlorinated diphenyl and/ or teiphenyl product is referred to as chlorinated polyphenyl.

While the chlorinated diphenyls and/er terphenyls may be used alone as the binder and burning rate modifier, for certain purposes it may bedesirable to incorporate additional resinous compounds therewith for the purpose of increasing the tack and strength of the binder. For this purpose, I may use any resinous materials such as The phenolic constituent of these phenol-formaldehyde resins may be ordinary phenol, cresol, para-phenyl phenol or tertiary butyl phenol. These resins are employed in the heat-reactive condition so that upon heating, which may take place at a lower temperature, they become infusible and insoluble. When oil-soluble phenolic resins such as the para-phenyl phenol-formaldehyde or tertiary butyl phenol-formaldehyde resins are employed, the binder may These solvents may be drying oil such as tung or linseed oil. Phenol-formaldehyde resins in the B stage are soluble in alcohol and may be added while dissolved in this type of solvent.

On the other hand, urea-formaldehyde resins in theheatreactive statemay be employed as solutions in toluene; xylene and butanol. These resins may be prepared as d'eescribed' in Uhited- StatesPatent No. 2,171,882, issued September 5, 1939.

The binder is incorporated into the gas generating compositionby simple mixing'withthe gas forming materials. If the mixture of gas 'formingmaterial and binder is rolled upon slightly heated rolls for a few minutes; a more intimate mixing of the ingredients is obtained. Where a solvent is present inthe bindercompositiomthe material may also berolled upon cold rolls. Pigment rolls such as areemployed in the paintindustry may be'used.

During rolling, any'solvent present in theresinous binder is" readily evaporated and the operation of rolling desirably should be continued until' a. dry, powdery material free of solvent is obtained.

In order to avoid adversely affecting the internal'ballistics of the propellant, a restricted amount of resinous bindershould be employed; namely, an amount of resin merely sufiicientto enable the production of the mechanically strong grain to be achieved. Usually from 5% to 10% by weight of resin 'mthe finished grain is suflicient to obtain the desired mechanical properties without adversely affecting the burning characteristics ofthe composition. In some cases, as little as 3% of resin as binder may be satisfactory.

III. COMPOUNDING THE INGREDIENTS In producing the composite propellant of the present invention the oxidizing component (for example, potassium nitrate) is preferably first dried and then ground to a finely divided condition. The powdered oxidizable component (for example, ammonium picrate) is mixed with the oxidizing agent, the former likewise being in a finely powdered condition; 'The chlorinated polyphenyl binder with or without aflresinous binder is next added and thoroughly incorporated therewith. As stated above,

grain is desirably cured at a temperature sufficient to render the resin insoluble and infusible. Temperatures between 30 C. and 80 C. may be employed for curing the resin. Condensation catalysts may be present in. the composition in order to accelerate the curing reactions.

IV. CEMENTING AND' COATING THE GRAINS Because of the powdery nature of the composition resulting from the incorporation of the resinous binder with the solid gas generating ingredients an inherently high degree of internal friction in the pressing operation renders it difiicult to mold very low grains. Where such long grains are desired, a plurality of short, readily molded grains may be cementedtogether by means of any suitable cement containing thermosetting resins such as alkyd resins, etc., the resulting composite fabricated grains exhibiting excellent properties, as will be herein after described. l

For many jet propulsion applications. it is of considerable advantageto be able to restrict the burning ofthe fuel body to certain parts of its: surface, either for the purpose of producing a-grain of neutral burning area, or

for the purpose ofrestr icting. the burning of the grain to a particular area of the grain. The compositions of the mesh standard screen size.

.present invention are particularly adapted to the formation of such. restricted burning; grains inasmuch as the binder will not ditfuse into and" adversely affect coating materials designed to prevent burning on certain parts of the surface. I

As the result of an extensive survey, it has been found that practically anystandard varnish" or' paint containing either a" drying oil such as linseedv oil or an alkyd resin produces an excellent flame-resisting coating Thus a large variety of paintsand varnishes including standard spar varnish, automobile paint, barn and :roof paint; asphalt varnish and many other types of available coat ing material maybeused'as flame-resistingcoatings'. The coating materials may be conveniently applied totthei grains by painting, sprayingor dipping, followed'by dry ing in. any manner. suited to thecharacter of the applied coating. Thereafter the coated surface may be additionally protected by means of adhesive textile tapes out by other suitable means. Such coatings have been found to withstand pressures well over Z000 lbs./in.

v. EXAMPLE In order. more clearly to disclose the nature of the present invention,. a preferredvembodiment will nowbe described in considerable detail. It should be clearly understood, however, that this is done solelyfor the purpose of. illustrating the principle of the invention lay-means of a concreteexample. Accordingly,.the followingdetailed description. is not-to be construed as a' limitation upon the spirit or scope of theinvention whichis more particularly defined in the. appended claims. K

In producing the preferred gas generating composition: of the present. invention, commercially pure potassium nitrate is first dried to" less than i of water, them ground to a particlegsize preferably to 70% 'minus 3251 The dry, powdered potasw sium nitrate is thoroughly mixedwith finely precipitated: ammoniumpicratein-the proportionof 55:45 byweight.

A: nomcrystalline; chlorinatedpolyphenyl resin suchrase is described in Example VI: ofUnitedStates Patentt1,892;a- 400 inpowdered form is mixed therewith inthepropor tions of parts by Weight of the potassium nitrate-ammonium picrate mixture to 10'parts by weight of chlo= rinated. polyphenyl resin. The. powdery mixture is thenincorporated on heated rolls forr'a few minutes; At the:

completion of'rolling, the. material is allowed to'cool -and then again finely powdered. The powder so produced'is formed into a grainby'pressingin aheated die.

Thegrains are now ready for use either as formed or after cementing several grains together to-form a larger grain orafter coating with a flame-resisting material to: form restricted burning grains." Cementing may he conveniently carried out by applying a thin coat of co ment (alkyd resins such as Glyp tal 1201) to thesurfaces to be joined, pressing the two surfaces together and maintaining a light pressure on the joined portions during the curing operation. Restricted burning grains may be pro duced by spraying a selected area such as the ends of a perforated cylindrical grain if neutral burning is required, or the sides and one end of a large, solid, cylindrical grain with any commercial coating material. containing. linseed oil or an alkyd resin The coated surf-acetmay be additionally protected by applying an adhesive coated: fabric tape over the resin coating.

VI. PROPERTIES OF THE' COMPOSITE PROPELLANT Table I1 summarizes. the ballistically importantt DIOR" erties of the two specific compositions in accordance'withw the present invention. For purposes of comparison the corresponding data on ballistite are also given.

varied over a wide range.

1 The composition listed as C. P.1, contained the following ingredients in percent by weight: 45% NaNO 45% ammonium picrate and 10% of a chlorinated diphenyl-polyphenyl resin.

The composition listed as C. P.-2, contained the following ingredients in percent by weight: 47% NaNOa, 47% ammonium picrate, 4.3% of a urea-formaldehyde resin and 1.7% of a chlorinated diphenyl resin. 1

From the foregoing data it will be apparent that the composite propellant of the present invention is characterized by the following advantageous properties:

1) The material has highly reproducible ballistics. The logrithmic plot of pressures against A /A is a straight line over the range of from 1,000 to 4,000 p. s. i.

(2) The linear rate of burning of the present trials can be varied over a wide range. This may be accomplished by changing either the specific composition of the powdery gas generating composition or the specific composition of the binder. Thus, the present propellant lends itself to a wide variety of uses requiring entirely different burning rates.

(3) The rate of burning has a low dependence on pressure. The exponential constant n in the burning law has a value of about 0.4 to about 0.5, depending on the composition over a pressure range of from 500 to 14,000 p. s. i. for grains of neutral burning area. From this it follows that the pressure in the rocket motor will vary as the 1.7 power of the A to A ratio. For comparison, the value of u for smokeless powder is about 0.7 and the area-pressure exponent is about 3.7. Because of the low value of n for the composite propellant of the present invention, a much smaller change in chamber pressure will result from any irregularity in burning which causes a change in the burning area or from variations in orifice or throat area. Furthermore, the low it value insures a lower pressure drop along a long grain than in the case of smokeless powder. Together with the high reproducibility of the chamber pressure, it permits the use of lighter chamber Walls and generally a lower factor of safety in motor design.

(4) The rate of burning has a low dependence on temperature. In the case of the present fuels, over the range from 40 to +60 C., the pressure increases only about 0.50% for each degree centigrade rise in temperature. For smokeless powder the corresponding figure appears to be of the orderof 15%, per 10 C.

(5) The value of K (i. e., A to A ratio) may be This may be accomplished by modifying the specific composition of the grain.

(6) The specific impulse is satisfactorily high (of the order of 160-170 for optimum expansion ratio).

(7) The composite propellant has a high density (e. g., about 1.75 to 1.85 grams per cc.), which permits an appreciably higher load density than with smokeless powder (density about 1.63 grams per cc.). In addition, the low values of n and K (see items 2 and 4) permit the use of smaller port areas in the motor chamber and this also favors high loading density.

(8) The composite propellant has a high crushing strength (about 5,000 to 12,000 p. s. i. depending on the composition) and suffers no significant distortion under stresses short of those required for fracture.

(9) It may be molded to close dimensional tolerances and requires no substantial amount of finishing by machining operations.

(10) The impact sensitivity of the material is satisfactory (approximately the same as that for ammonium picrate).

(11) The chemical stability of the material is satisfactory as judged by the usual accelerated tests. The ballistic properties of grains burned after storage for several months have been satisfactory in that no change has taken place. Many grains have been subjected to a temperature cycle of 8 hours per cycle between +60 C. and 45 C. for 20 cycles without showing any significant change in ballistic properties, in density, or in compression strength.

(12) The burning of the cemented grains shows no irregularities whatever arising from the composite, builtup or fabricated structure.

(13) The restriction of the burning area by means of protective coatings is entirely successful. The grains contain no diffusible liquid, such as nitroglycerine, which has caused so much trouble in attempts to restrict burning of double base powder grains.

What I claim is:

i. A composite jet propulsion propellant essentially composed of a dense, compact mixture of crystalline particles of ammonium picrate and particles of a crystalline inorganic nitrate selected from the class consisting of sodium nitrate, potassium nitrate, barium nitrate and ammonium nitrate, said mixture containing between 10% and 55% of said nitrate, the balance of said mixture being particles of ammonium picrate and from 5% to 10% of a resinous matrix for said particles, said matrix consisting of a material selected from the class consisting of resinous chlorinated polyphenyls containing at least 40% of chlorine and mixtures of chlorinated polyphenyls containing at least 40% chlorine with a urea-formaldehyde resin.

2. A composite jet propulsion propellant essentially composed of a dense, compact mixture of crystalline particles of ammonium picrate and potassium nitrate, said mixture containing between 10% and 55% of said nitrate and the balance thereof being ammonium picrate and from 5% to 10% of said mixture of a resinous matrix for said particles, said matrix consisting of a chlorinated polyphenyl containing between 42% and 65% by weight of chlorine.

3. A composite jet propulsion propellant essentially composed of a dense, compact mixture of crystalline particles of ammonium picrate and vpotassium nitrate, said mixture containing between 10% and 55% of said nitrate and the balance thereof being ammonium picrate and from 5% to 10% of said mixture of a resinous matrix for said particles, said matrix consisting of a chlorinated polyphenyl resin containing between 42% and 65% by weight of chlorine, said propellant having a density of 1.92.

4. A composite jet propulsion propellant essentially composed of a dense, compact mixture of crystalline particles of ammonium picrate and potassium nitrate, said mixture containing between 10% and 55% of said nitrate and the balance thereof being ammonium picrate and from 5% to 10% of said mixture of a resinous matrix for said particles, said matrix consisting of a mixture of a urea-formaldehyde resin and a chlorinated polyphenyl resin containing between 42% and 65% by weight of chlorine, said propellant having a density of 1.79.

5. A composite jet propulsion propellant essentially composed of a dense, compact mixture of crystalline particles of ammonium picrate and sodium nitrate, said mixture containing 45% sodium nitrate, 45 of ammonium picrate and a resinous matrix for said particles, said matrix consisting of 10% of a chlorinated polyphenyl resin containing between 42% and 65% of chlorine.

6. A composite jet propulsion propellant essentially composed of a dense, compact mixture of crystalline particles of ammonium picrate and sodium nitrate, said mixture containing 47% of sodium nitrate and 47% of ammonium picrate and a resinous matrix for said parti- 1 .1 12 0123;.8311?matliiXLCOnSiSTing of 413%" ofimurfimfbrmalder 2,409,111 Davis Oct. 8, 1946 hyde resin and 1.7% of a chlorinated polyphenylzresinw 2,433,417 Bitting et a1 Dec. 30, 1947 centaini'ngzbetween; 42%: andi 65%: Off chlorine; 2,434,872 T-aylbr Jim. 20} 1948 Referenceszfiitedin'thezfila'ofthis patent w 1 PATENTS 4 UNITED STATES PATENTS 6,258 Great Britain A.D,,1892

363,-224 Gerhard- May 17 ;,18 87 9,062 Great'Biitain DJ 1899 1,892,400 Jenkins Dec. 27, 1932 21,529 Great, Britain A.: D; 1905' 1,975,072 Booth Oct. 2, 19 34 10, 338,848 Germany "July 4; 1921- 2,159,234 Taylor May 23,1939 1 9 2,165,263 Holm Q ,Ju1y11, 1939' OTHER REFERENCES 4 4 195 955 Helm Apn 1 4 Penning: Chlorinated Diphenyl, Ind: andEng,

2,3 5,170 Bitting -,19, 19 4, Chem.,November 1930, pages 1180iand 1:182.

- UNITED STATES PATENT OFFICE CERTIFIQATE 0F CQRREC'HUN Pater-r- No 2, 857,25

Bomber 21, 1958 It is hereby certified that error appears in the printed specification of the above numbered patent requiring correct-ion and that the said Letters Patent should readas corrected below.

Colman l, 76, for "depedence", occurrence, read depe ems column line 1, for "unit" read we unity column 7, line 42, for "thermos-Easting" thermcse' ating line 62, for "low" read long Signed 31st of May 1960 (SEAL) fittest:

143mm ROBERT C. WATSON Attesting Officer Commissioner of Patents UNITED STATES PATENT OFFICE CERHFMATE @F QQRRE CHQN Patent Nou 2,857,125.

Gctober 21, 1958 12L "I r1 v (Juli-Tries A, Thomas It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should readas corrected below.

6011mm. 1, line 7 3, s d column 2, 28, de-pedence each occurrence, read enc'e ===3 column 3, iirie' l, for "unit read w unity 5 column "7, 42;, for "thermostat =thermosetting 62, for New" m long we Signed 31st of May 1960 (SEAL) fittest:

KARL AXLTTTE ROBERT C. WATSON Arresting Ufiicer fiommissioner of Patents

Claims (1)

1. A COMPOSITE JET PROPULSION PROPELLANT ESSENTIALLY COMPOSED OF A DENSE, COMPACT MIXTURE OF CRYSTALLINE PARTICLES OF AMMONIUM PICRATE AND PARTICLES OF A CRYSTALLINE INORGANIC NITRATE SELECTED FROM THE CLASS CONSISTING OF SODIUM PITRATE, POTASSIUM NITRATE, BARIUM NITRATE AND AMMONIUM NITRATE, SAID MIXTURE CONTAINING BETWEEN 10% AND 55% OF SAID NITRATE, THE BALANCE OF SAID MIXTURE BEING PARTICLES OF AMMONIUM PICRATE AND FROM 5% TO 10% OF A RESINOUS MATRIX FOR SAID PARTICLES, SAID MATRIX CONSISTING OF A MATERIAL SELECTED FROM THE CLASS CONSISTING OF RESINOUS CHLORINATED POLYPHENYLS CONTAINING AT LEAST 40% OF CHLORINE AND MIXTURES OF CHLORINATED POLYPHENYLS CONTAINING AT LEAST 40% CHLORINE WITH A UREA-FORMALDEHYDE RESIN.