US Government As Represented by the Secretary of the Army

Trw Limited

William M Chew

James A Murfree, Jr

Orval E Ayers

Pasquale Martignoni

Leo K Asaoka

Douglas L May

Darren M Thompson

Henry A Nappier

Barry D Allan

Jerrold H Arszman

William D English

Jay S Lilley

A gas generator propellant formulation suitable for use in an air turbo ret (ATR) which employs an air breathing system that uses fuel gases produced by a gas generator propellant to operate the engine's turbine is provided which can also be used with other airbreathing propulsion systems that require a high gravimetric heating value (GHV). The basic fuel gas generator propellant formulation comprises in weight percent a tetraalkylammonium borohydride 50-100; lithium nitrate 0-50; and optional additives of hydroxy proply cellulose 0-20 and silica or silicon 0-20. The basic fuel gas propellant formulation can also employ an encapsulated tetraalkylammonium borohydride which employs an encapsulation polymer selected from the group consisting of polyethylene, polypropylene, and ethyl cellulose. When employing an encapsulated tetraalkylammonium borohydride a binder is employed selected from the group consisting of polybutadiene and polyether cured with 0.50% selected from hexamethylene diisocyanate and isophorene diisocyanate. The encapsulated fuel gas generator propellant formulation comprises an encapsulated tetraalkylammonium borohydride 50%; binder 0-45%; and lithium nitrate 5%. Lithium nitrate in the fuel gas generator propellant formulation enables the composition to be ignited with a hot wire. The tetraalkylammonium borohydride is selected from the group of tetraalkylammonium borohydrides consisting of tetramethylammonium borohydride, tetraethylammonium borohydride tetrapropylammonium borohydride, and tetrabutylammonium borohydride.

Fuel gas generator for airbreathing propulsion systems

Elemental silicon is a solid high energy material which provides an advane when added to gel, hybrid, and ducted rocket fuels by increasing both specific impulse, lsp, and density specific impulse, .rho.*lsp. The quantity added depends on the specific applications for which the formulation will be used. The usual concentration ranges from about 0.5% to about 70% by weight. The important parameters to consider during formulation are particle size, concentration, combustion efficiency, physical properties, and plume signature. Comparisons for 50% solid fuel loading in a gel bipropulsion system predicts a maximum lsp of 286 lbf.s/lbm as compared to 267 lbf.s/lbm for carbon--a 7% increase. The .rho.*lsp produced by silicon is 14.5 lbf.s/cubic inch as compared to 13.7 lbf.s/cubic inch produced by carbon--a 7% increase. A 25% solid loading in solid fuel-gas generators for the hybrid rocket produced a maximum lsp of 278 lbf.s/lbm as compared to 267 lbf.s/lbm produced by carbon--a 4% increase. The .rho.*lsp produced by silicon is 14.8 lbf.s/cubic inch as compared to 14.1 lbf.s/cubic inch produced by carbon--a 5% increase. Another advantage for silicon loaded gel fuels is the large 'plateau' in the performance versus oxygen/fuel curves, and, resulting in a less stringent oxidizer-to-fuel ratio (O/F) control in an operational system.

Silicon as a high energy additive for fuel gels and solid fuel-gas

A pressure controlled pintle is employed in combination with a throttling quid, gel, or hybrid engine to provide a constant pressure and variable thrust from a single operating engine. As the propellants are throttled back and the chamber pressure drops, the pintle moves and closes the gap between the pintle and nozzle throat, thereby lowering the throat area and re-establishing the design chamber pressure related to pintle spring tension. By retaining the design pressure over a wide thrust range, the engine efficiency remains at the design value. This eliminates the drop of Isp due to pressure and keeps the cost of the system reasonable because only one engine is required. When a higher thrust is desired, a throttling valve in an injector increases the propellant flow rate, which causes a higher pressure in the combustion chamber. The constant pressure actuator moves the pintle to open the nozzle throat, which reduces the pressure to the design value. The design value may not be optimum. There are many size/temperature/volume trade off's relating to the missile as a whole which could move the design value from optimum. Because the pressure in the combustion chamber remains the same, the Isp is not greatly changed, but the thrust level increases because of the increase in the mass flow through nozzle. The combination provides substantially constant combustion chamber pressure for a single variable thrust bipropellant engine.

Constant pressure, variable thrust bipropellant engine

A propulsion system is disclosed comprising a glycidyl azide polymer (GAP) olid fuel generator (SFGG) that produces fuel-rich hot gases which are combusted in a combustion zone of a combustion chamber of a solid fuel ducted rocket. A basic embodiment comprises an airbreathing engine wherein a ducted member scoops air in from the atmosphere for hypergolic reaction with the fuel-rich hot gases for propulsion during a sustain stage of a flight. An augmentation of the basic embodiment is achieved by combusting the fuel-rich GAP SFGG effluent with inhibited red fuming nitric acid (IRFNA) gel oxidizer to produce higher thrust during the boost and dash stages of a flight. During the high thrust stages, the air ducts of the ducted member are closed and IRFNA gel is injected into the combustion chamber to react with the fuel-rich hot gases from the GAP SFGG. The resulting higher pressure in the combustion chamber gives the missile a correspondingly greater thrust than during the lower pressure airbreathing sustain stage of flight.

Solid fuel ducted rocket with gel-oxidizer augmentation propulsion

A gel/solid bipropellant propulsion system employs fuel-rich combustion gs from a solid gas generator and an oxidizer gel in a highly efficient combustion chamber wherein the fuel-rich combustion gases and the oxidizer gel are each metered through a vortex injector into a combustion chamber to produce a hypergolic reaction. The solid gas generator (SSG) has a preferred composition of glycidly azide polymer (GAP). The GAP SSG is composed of GAP diol and/or triol polymerized with a di-or tri-function isocyanate, such as isophorone diisocyanate. The gel/solid bipropellant propulsion system comprises the SSG in combination with an oxidizer storage/extrusion vessel system, a combustion chamber system, and a system controller which controls initial ignition of the SSG to produce fuel rich combustion gas which pressurize the system. The system controller monitors pressures and flow rates of fuel and gel oxidizer. System shut-down is achieved by closing valves in fuel-rich combustion gases supply line, gel oxidizer supply line, and a pressurization line to gel oxidizer storage/extrusion vessel. A blow-down line is opened to de-pressurize the SSG container which extinguishes the SSG. When start up is desired, a reignition shut-off valve is reopened which permits the injection of the gel oxidizer from the line retained under pressure and achieves reignition of the SSG.

Gel/solid bipropellant propulsion system with energy management

A mixture of at least two particulate metals capable of undergoing an exothermic reaction to form an intermetallic compound is provided to sustain decomposition of borane reactants to yield hydrogen or deuterium.

Solid propellant hydrogen generator

A process for producing a calcium chemical pump which includes reacting cium and anhydrous ammonia in a closed vessel that is cooled to a temperature below 0.degree. C. to form a solution of the calcium and anhydrous ammonia and then spraying the solution onto a rotating porous foamed substrate material in a closed container that has a vacuum pulled thereon, and the solution when sprayed causing the ammonia to flash and be evaporated and drawn off by the vacuum to cause the calcium to be deposited on the rotating porous foamed substrate material.

Supports and preparation process for the manufacture of a calcium

The use of a class or compounds known as amine-boranes and their derivati in solid propellants to produce or generate hydrogen or deuterium upon combustion.

Amine-boranes as hydrogen generating propellants

A catalyst bed containing alumina pellets on which an active catalyst metal selected from iridium, nickel, niobium, and molybdenium has been deposited is employed to decompose a compound selected from deuterohydrazine, deuteroammonia, hydrazine, and ammonia to yield ammonia free deuterium and nitrogen or hydrogen and nitrogen at a temperature required for immediate use in a DF or HF laser which uses F atoms as the fuel. The decomposition temperature of the catalyst bed is maintained by a hypergolic reaction produced from reacting a fuel selected from the group consisting of hydrazine, methylhydrazine, 1,2-dimethylhydrazine, and blends of the same with an oxidizer selected from the group consisting of inhibited red fuming nitric acid, dinitrogen tetroxide, chlorine trifluoride, and chlorine pentafluoride. A laser employing ammonia free decomposition products of hydrazine and ammonia produced at a temperature between about 500.degree. C. and 900.degree. C. operates at a higher power output. When NH.sub.3 is present in the H.sub.2 and diluent gas, N.sub.2, a decrease of 20% in the output is experienced for each 1-2% NH.sub.3 up to about 8% concentration.

Hydrogen gas generator from hydrazine/ammonia

A cyano compound fuel selected from the group consisting of dicyanoacetylene (DCA), tetracyanoethylene (TCE), and tetracyanoethylene oxide (TCEO) when reacted with an oxidizer compound selected from the group consisting of fluorine (F.sub.2), nitrogen trifluoride (NF.sub.3), chlorine trifluoride (ClF.sub.3), chlorine pentafluoride (ClF.sub.5), and tetrafluorohydrazine (N.sub.2 F.sub.4) produces the F.sup.. atom concentration required for either HF or DF lasers. The reaction is accomplished in the presence of a diluent gas selected from nitrogen and helium. No deactivation species are among the gaseous species produced which include CF.sub.4, F.sup.. atoms, and N.sub.2 ; therefore, deactivation of the excited molecules, either HF or DF, which are responsible for the lasing in a HF or DF laser is prevented. A higher performance of the laser device can be achieved.

Cyano compounds as fuels for HF or DF lasers

Disclosed are storable solid propellant compositions based on complex metal oron compounds of the general formula M(BH.sub.4).sub.x or M(BD.sub.4).sub.x, (where M equals a metal and x equals the valence of the metal M; M is an alkali metal or an alkaline earth metal; H is hydrogen, and D is deuterium) and ammonium salts of the general formula (NH.sub.4).sub.n Y or deuteroammonium salts of the general formula (ND.sub.4).sub.n Y (where Y represents an anion with a total charge of n; N is nitrogen, H is hydrogen, and D is deuterium) combined stoichiometrically or in varying molar ratios. The stoichiometric blend is employed in a method for producing hydrogen or deuterium that contains nitrogen as an inert diluent and is acceptable for use in HF/DF chemical lasers, the gas dynamic laser (GDL), or as a source to generate hydrogen containing an inert diluent.

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Huntsville, AL, United States of America

William M Chew