US Government As Represented by the Secretary of the Army

Barry D Allan

William M Chew

Darren M Thompson

Jerrold H Arszman

Porter H Mitchell, Jr

A method process to convert inhibited red fuming nitric acid (IRFNA) and/or nitrogen tetraoxide to either dilute or concentrated (98%&plus;) nitric acid. The method describes a process to remove all of the normal inhibitors (if required), that have been reported to been used in IRFNA. The process described will provide nitric acid free of contaminates which are undesirable when using the nitric acid in reactions to produce other products.

Nitric acid production

A thixotropic oxidizer gel comprising inhibited red fuming nitric acid (IA) as the carrier with lithium nitrate (LiNO.sub.3) suspended therein and gelled with a gellant agent of SiO.sub.2 having a mean particle size of 0.015 microns has the rheological properties which can be tailored to match those of MICOM GEL, a fuel gel. A thixotropic gelled fuel (MICOM GEL) has been of particular interest because of its increased safety, reduced sloshing, ease of pumping at zero gravity and ability to suspend high concentrations of high-energy ingredients. However, a gelled oxidizer has been desired for use with the gelled fuel to constitute a thixotropic gelled propellant system. The combination of a gelled fuel (MICOM GEL) and a gelled oxidizer is now a reality after the development of the thixotropic oxidizer gel disclosed above. Of major significance is the matching of the rheologial properties of the two gels so that an oxidizer/fuel (O/F) ratio shift does not occur with a temperature change. The development of the thixotropic oxidizer gel obviates the problems of O/F shift attributed to using a liquid IRFNA oxidizer with MICOM GEL. The combination of the thixotropic oxidizer gel comprising the carrier of IRFNA in weight percent amounts from about 55.0 to 86.0, the suspended LiNO.sub.3 in weight percent amounts from about 10.0 to 40.0, and the gellant agent of SiO.sub.2 in weight percent amounts from about 4.0 to about 5.0 with MICOM GEL fuel offers both high Isp and high density Isp which translates to significant increases in total system performance. This combination reflects a range increase to 160 percent of the present system.

Thixotropic IRFNA gel

A high density inhibited red fuming nitric acid oxidizer gel is disclosed ich results in an improvement from 0.5% to about 1.0.% in the impulse over a baseline formulation containing 14% nitrogen tetroxide. An improvement from about 3.0% to about 6.0% is achieved in the density impulse baseline formulation. The higher density inhibited red fuming nitric acid is derived by adding from about 15 percent by weight to about 45 percent by weight percent of nitrogen tetroxide to nitric acid in an amount from about 80 percent by weight to about 40 percent by weight. The other ingredient of the oxidizer gel comprise a gellant of about 0-10 percent by weight, water from about 0-4 percent by weight, and an inhibitor agent of about 0-1 percent by weight. IRFNA is inhibited with phosphoric acid, iodine compounds, or hydrogen fluoride which is present in the oxidizer gel as an additive. The higher density IRFNA oxidizer gel or liquid can be used in airbreathing propulsion systems; a bipropellant formulation is used to provide variable thrust. The oxidizer can also be used with air turbo rocket propulsion systems to augment air combustion with fuel gases. It can be used in a liquid or gel/solid system wherein the oxidizer is sprayed in contact with a solid propellant.

Higher density inhibited red fuming nitric acid (IRFNA) oxidizer gel

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 fiber optic adhesive composition for applying to a fiber optic having a ffer coat thereon and subsequently, partially cured to a tacky outer surface prior to its being wound onto a bobbin from which the adhesively coated fiber optic material is to payout during use to transmit a signal to a missile in flight. The partially cured adhesive composition functions to hold the fiber optic material in place on the bobbin during storage and allows consistent payout during use of the fiber optic material. The typical composition of the fiber optic adhesive comprises hydroxyterminated polybutadiene from about 88.14 to about 92.48 percent by weight, isophorone diisocyanate from about 6.23 to about 6.42 percent by weight, a catalyst of ferric acetylacetonate or dibutyltin dilaurate in an amount from about 0.89 to about 1.15 percent by weight respectively, and a thixotropic agent in an amount of about 4.48 by weight.

Fiber optic adhesive

Disclosed is a method and a fiber optic adhesive which composition is appd to a fiber optic having a buffer coat thereon and is, subsequently, partially cured to a tacky outer surface while being wound onto a bobbin from which the adhesively coated fiber optic material is to payout during use. The adhesively coated fiber optic material must be cured to a tacky cure while being wound onto a bobbin. The cured adhesive composition functions to hold the fiber optic material in place on the bobbin during storage and allows consistent payout during use of the fiber optic material. The typical composition of the fiber optic adhesive comprises hydroxyterminated polybutadiene from about 88.14 to about 92.48 percent by weight, isophorone diisocyanate from about 6.23 to about 6.42 percent by weight, a catalyst of ferric acetylacetonate of dibutyltin dilaurate in an amount from about 0.89 to about 1.15 percent by weight respectively, and a thixotropic agent in an amount of about 4.48 by weight.

Method of applying a fiber optic adhesive to a fiber optic material

The incorporation of methyl alcohol into a hydrazine, and hydrazine nitrate uel blend is effective in lowering the freezing point of the combination while enhancing the performance of the monopropellant blend by contributing to the total energy of the monopropellant ternary combination. Hydrazine content varies from about 58 to about 68 weight percent, the hydrazine nitrate varies from about 20 to about 25 weight percent, and the methyl alcohol varies from about 12 to about 17 weight percent. The freezing point of this monopropellant fuel blend has a freezing point from about -29.degree. F. to about -65.degree. F., which renders this monopropellant fuel blend useful as a tactical monopropellant fuel blend over a wide temperature range.

Tactical monopropellant

A method of reducing the visible flash caused from afterburning of a rocket otor by injecting a fire extinguishing suppressant material into the exhaust gases from the rocket motor and injecting the fire extinguishing suppressant material near the exhaust end of the rocket motor nozzle and about an internal periphery of the exhaust nozzle. An effective fire extinguisher suppressant includes fluoro halogenated carbon compounds and specifically CBrF.sub.3.

Afterburning reduction

The incorporation of a nitrated pentaerythritol additive selected from the ono-, di-, tri-, and tetra-nitrated pentaerythritols into hydrazine is effective in lowering the freezing point of the combination while enhancing the performance of the monopropellant by contributing to the total energy of the monopropellant combination. Hydrazine content varies from about 65 to 95 weight percent while the additive of a nitrated pentaerythritol varies from about 5 to about 25 weight percent. An optional additional additive of methyl alcohol from about 5 to about 20 weight percent can be employed with a corresponding adjustment in weight percent of hydrazine when said additive of methyl alcohol is employed in addition to said additive of said nitrated pentaerythritol.

Nitrate ester monopropellant

A thixotropic rocket fuel composed of monomethylhydrazine, metallic fuel particles, dimethylurea, and a gellant. The particular thixotropic fuel is particularly characterized by the fact that a low gellant concentration can be used and by the fact that the metallic fuel particles can be suspended with no separation or settling out of the metallic fuel particles in the fuel even when subjected to 500 g's. The particular thixotropic rocket fuel has high density quality and high specific impulse values.

Gelled monomethylhydrazine thixotropic fuel

A submicroscopic particulate silica having a particle size range from about 5-20 m.mu. that is prepared in a hot gaseous environment at about 1100.degree. C by the vapor phase hydrolysis of a silicon compound is reacted with liquid water in a ratio in weight percent of about 1 part water to about 9 parts water to 1 part of the particulate silica to yield a powdered product which remains flowable over a wide temperature range -- even when cooled to an extremely low temperature of -196.degree. C. The adsorbed water is liberated on heating the powdered product. The powdered product with adsorbed water up to about 90 weight percent has utility as a coolant by liberating water on heating. The powdered product is useful as moisture source for miscellaneous purposes over a wide temperature range.

Dry water

Liquid monomethylhydrazine is converted to a thiotropic gel by dispersing erein a cellulose or hydroxyalkyl-substituted gelling agent. The gel thus obtained can be handled and stored on board a rocket motor without the hazards associated with liquid monomethylhydrazine.

Growing community of inventors

Huntsville, AL, United States of America

Barry D Allan