US Government As Represented by the Secretary of the Army

Leo K Asaoka

William M Chew

Douglas L May

William D Stephens

Darren M Thompson

Larry C Warren

Jay S Lilley

Christi L Salter

Sticky high water content gelled fire extinguisher compositions hold the antage of providing a high water content, slightly viscous (sticky) gel with flow properties similar to water. The ability of this material to stick to burning surfaces is what sets it apart from water extinguishers. Not only are fires extinguished, but also surfaces are cooled by the sticky gel as the water evaporates. The basic gelled fire extinguisher composition is comprised of about 88 weight percent water and about 12 weight percent of a 7 nanometer particle size silicon dioxide gellant. The silicon dioxide gellant is available as EH5 tradename by Cabot for this silicon dioxide gellant. Other ingredients such as dispersants, wetting agents and flame retardants can be used as additives in combination with the gelling agent. The actual gel system is inexpensive, made from readily available ingredients and easily prepared.

Sticky high water content gels for extinguishers

The addition of silicon (Si) powder from about 0.40 to 6.00 weight percent o ammonium nitrate (AN) propellant formulations as a fuel source results in a substantial increase in performance specific impulse (Isp). Theoretical Isp of AN propellant can be enhanced to levels approaching conventional in-service propellant formulations containing much more hazardous ingredients. Using inert or energetic polymer binders, AN propellant formulations are possible that will meet the performance requirements of most tactical missile systems when silicon is used as a fuel additive. Silicon powder when used to replace elemental carbon in most formulations has two major advantages: (1) an increase in theoretical Isp and (2) an improved propellant combustion efficiency by increasing propellant burning temperature. An improvement in propellant burning properties are also expected. The adjustment of weight percent ammonium nitrate in the AN propellant formulation is made as the silicon powder is adjusted over the range of 0.40 weight percent to 6.00 to achieve the preferred results. Formulations are mixed, cast and cured by techniques and methods that are commonly used in the industry and that are known by personnel skilled in the art of propellant formulating.

Silicon as high performance fuel additive for ammonium nitrate

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 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.

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Huntsville, AL, United States of America

Leo K Asaoka