Abstract:
An invention for securing a boss (40) to a thermoplastic liner (12) of a pressure vessel (10) is disclosed. A preferred method of forming the vessel (10) includes inserting a thermoplastic projection (32) of the liner (12) into a mounting aperture (52) located in the boss (40). The projection (32), which is rigidly attached to the liner (12), mechanically prevents rotation of the boss (40) about a pressure chamber orifice (18) relative to the liner (12). The method further includes melting and compressing the thermoplastic projection (32) to conform it to a locking chamber (54) in the mounting aperture (52). A composite case is then constructed over the thermoplastic projection (32), the liner (12), and the boss (40), using the liner (12) as a mandrel. The thermoplastic liner (12) and projection (32) are integrally formed by blow-molding thermoplastic material into a die (64) without any substantial use of injection-molding. A vessel constructed according to the method is also disclosed.
Abstract:
A solid propellant dual pulse rocket motor (10) has a pressure vessel (12) containing two pulse grains (24, 26) separated by a barrier insulator (32). An igniter assembly (36) disposed at a fore end (16) of the pressure vessel (12) selectively ignites a first pulse grain (24) from a central cavity (34). The igniter assembly (36) also ignites a second pulse grain (26) by ejecting hot combustion gases onto the fore end of the grain.
Abstract:
An apparatus is disclosed for stage separation and thrust termination in a multi-stage missile having an upper stage (14) detachably connected to a lower stage rocket motor (12). The apparatus includes a piston (16) located at the forward end of the lower stage rocket motor (12) in fluid communication with the motor's combustion chamber (18). The piston (16) is configured with a plurality of venting passages (48), and capable of deployment from a stowed position, in which the venting passages (48) are sealed, to an extended position, in which the venting passages (48) are unsealed. The venting passages (48) are preferably configured to vent the combustion chamber (18) at an angle to the upper stage (14), providing the lower stage rocket motor (12) with a component of thrust away from the upper stage (14) after detachment, without damaging the upper stage (14).
Abstract:
Chemorheologically viscosity tailored matrix resin formulations for use in forming prepregs and composite articles are disclosed. These formulations have a specified viscosity profile obtained from a curable matrix resin and an effective amount of a reactive resin curing agent reactive at room temperature and a latent resin curing agent substantially nonreactive at room temperature. The latent resin curing agent is activated upon heating or radiation. The matrix resin formulation is adapted upon formulation to have a viscosity sufficiently low enough to enable the matrix resin to impregnate fibers or broadgoods at room temperature without the necessity for the application of heat or solvent and which, upon standing at room temperature after impregnation into the fibers or broadgoods to form a prepreg composition, rises in viscosity. The matrix resin in the prepreg experiences a reduction in viscosity upon heating to a viscosity minimum sufficiently low to allow the matrix resin to flow and substantially eliminate formation of voids in the composite article from said prepreg yet not so low as to permit excessive bleeding of the matrix resin from the prepreg. With continued heating, the matrix resin in the composite article cures to a hardened or gelled state.
Abstract:
A computer-implemented system and method for evaluating gas bag inflator designs are disclosed, including an inflator state machine having slots for signals corresponding to predetermined gas dynamic and heat transfer characteristics of a gas bag inflator at a specified time. Inflator state machines having one or more chambers, and zero or more deflectors, screen packs, burst disks, and vents are supported. Initial temperatures, pressures, and chamber gas contents may be specified, as may the geometry and other characteristics of gas generant pills. A controller in the state machine accesses a chemical database to obtain information about enthalpy, viscosity, and other properties of gas generant combustion products, igniter combustion products, and other compounds present within the gas bag inflator. Running the state machine produces predictions of pressure and temperature behaviour within a fabricated gas bag inflator, permits elimination of gas bag inflator designs that are unlikely to meet predetermined performance goals, and provides explanations for unexpected test results of fabricated inflators.
Abstract:
Methods of preparing bis-(1(2)H-tetrazol-5-yl)-amine (BTA) having improved physical and chemical characteristics are disclosed. In the process, a dicyanamide salt and an azide salt are reacted at high temperature in the presence of an acid reagent. Best yields are obtained when the reaction is allowed to proceed for approximately 48 hours. The dicyanamide salt is preferably present in a stoichiometric excess. The acid reagent has a pKa in the range from about 3 to about 9. The reaction mixture is acidified to a pH less than 3. Several variations of the acidification step permit control of particle size and morphology. Small, rounded particles are prepared by rapidly cooling the hot crude reaction product coincidentally with acidification. This is preferably accomplished by adding the hot crude reaction product directly to cold concentrated acid. The precipitated particles are isolated to yield BTA.
Abstract:
A sodium-azide-free gas-generating composition includes an oxidizable borohydride fuel and an oxidizing agent containing oxygen and a metal. The fuel and the oxidizing agent are selected such that water vapor is produced upon reaction between the borohydride fuel and the oxidizing agent. Suitable oxidizing agents contain a metal and oxygen and are selected from a metal oxide, a metal oxide hydrate, a metal oxide hydroxide, a metal hydrous oxide, a metal hydroxide, or mixtures thereof. The fuel and oxidizing agent are selected such that water vapor is the major gaseous combustion product.
Abstract:
A continuous extrusion process for manufacturing composite gun propellant is disclosed. The disclosed process is particularly suitable for preparing gun propellant formulations based upon a cellulose ester binder. In the process, the binder ingredients are dissolved in an organic solvent and then pumped directly into a twin-screw extruder. The other ingredients, except the oxidizer, may optionally be dissolved in the organic solvent prior to introduction into the twin-screw extruder. The oxidizer is dried, ground, and also fed dry to the twin-screw extruder. In the extruder, the materials are thoroughly mixed and the solvent is reduced to sufficient level for direct extrusion through the desired dies.
Abstract:
A sodium-azide-free gas-generating composition includes an oxidizable inorganic fuel, such as a metal, and an oxidizing agent containing oxygen and a metal. The fuel and the oxidizing agent are selected such that water vapor is produced upon reaction between the inorganic fuel and the oxidizing agent. Although a number of inorganic fuels can be employed, a suitable fuel can be a transition metal, another element such as silicon, boron, aluminum, magnesium, and intermetallic compound, hydrides of these metals and mixtures thereof. Suitable oxidizing agents are selected from basic metal carbonates and basic metal nitrates. The fuel and oxidizing agent are selected such that substantially nontoxic gases are produced such as mixtures of water vapor and either carbon dioxide or nitrogen.