Showing papers on "Propellant published in 1976"

Liquid rocket engine injectors

Abstract: The injector in a liquid rocket engine atomizes and mixes the fuel with the oxidizer to produce efficient and stable combustion that will provide the required thrust without endangering hardware durability. Injectors usually take the form of a perforated disk at the head of the rocket engine combustion chamber, and have varied from a few inches to more than a yard in diameter. This monograph treats specifically bipropellant injectors, emphasis being placed on the liquid/liquid and liquid/gas injectors that have been developed for and used in flight-proven engines. The information provided has limited application to monopropellant injectors and gas/gas propellant systems. Critical problems that may arise during injector development and the approaches that lead to successful design are discussed.

Expendable case ammunition

Abstract: Expendable case ammunition of the type which is expelled as a unit through the barrel of a firearm and whose case separates from contained projectiles in flight, comprises a body and a cap, and may include a separate projectile container. These parts are made of a deformable material such as plastic, and are snap-locked together. The body has an interior transverse wall separating a projectile chamber from a propellant chamber, which is enclosed by the imperforate cap to permit the use of loose propellant and to protect against contamination and accidental ignition. An anvil is integrally formed in the propellant chamber wall to cooperate with an internal primer and a firing pin which penetrates the cap. A diaphragm region of the cap is ruptured by initiation of the primer, and the cap remains attached to the body during ignition of the propellant and travel of the ammunition unit through the barrel of the firearm.

Effects of Propellant and Electrode Geometry on Pulsed Ablative Plasma Thruster Performance

Abstract: A performance level compatible with 30% thrust efficiency at 1500 s specific impulse at 1 mlb (4.45 mN) of thrust was demonstrated with the parallel rail pulsed ablative thruster using Teflon propellant. Parametric variations of interelectrod e spacing and included angle were performed. In addition, Teflon was replaced by other thermoplastics and was also seeded with 10% and 30% LiOH and InBr in an evaluation of alternative propellants. Both the conventional breech-fed and later side-feed electrode/propellant configurations were tested. With the same initial conditions it was shown that the breech-fed geometry yields higher thrust efficiency than the side-fed geometry because of the higher specific impulse generated (i.e., up to 5300 s using Teflon). Results of parametric studies indicate that, for high thrust/power and moderately high specific impulse, virgin Teflon propellant with an interelectrode spacing of 3.0 in. (7.62 cm) and zero degree interelectrode included angle in the side-fed configuration are best. A simple semiempirical analytic model is presented where it is shown that the broad range in performance characteristic of this device is related to the degree to which magnetoplasmadynamic and ordinary gasdynamic acceleration mechanisms can be made more or less dominant in the acceleration of the ablated propellant.

Radiative Ignition of Double Base Propellants: I. Some Formulation Effects

Abstract: In this first paper of a two part study, the ignition response to arc image radiative heating (5 to 100 cal/cm sec) of several double-base propellants is examined; comparisons with certain AP and HMX propellants are made also. Ignition delay is affected by chemical factors in propellant formulation (stability of the condensed phase, reaction rate in the gas phase) and by optical factors in propellant formulation (opacifiers affecting reflectivity and in-depth absorption). The results show that comparisons of the chemical factors in the formulation can only be made properly when the optical factors are minimized (as by carbon addition). When optical factors are minimized by opacifying the propellant, one finds, in order of increasing ease of ignitability, the formulations tested fall as follows: HMX composite, AP composite, double base (noncatalyzed), double base (catalyzed).

Oil and gas well stimulation

Abstract: A method and means for stimulating oil and gas wells to increase production comprises filling a well above the pay zone level with a fracturing fluid, then suspending a cylinder of high explosive centrally within the wellbore adjacent to the pay zone. Thereafter a propellant is suspended within tens of feet above the high explosive and the well above the propellant is enclosed. The application of high explosive is chosen to cause multiple radiating fractures but will not crush the rock in the well. Also, the rise time of the shock wave created by the explosive should be less than the time required for sound to traverse one-half of the periphery of the well opening in the rock at the pay zone. The propellant is detonated first, followed by the detonation of the high explosive. The purpose of using the propellant is to maintain pressure caused by the high explosive over a longer period, thereby extending the fractures caused by the high explosive.

Radiative Ignition of Double Base Propellants: II. Pre-ignition Events and Source Effects

Abstract: In this second paper of a two-part study, emphasis is on the pressure dependent pre-ignition events in double base propellants and the influence of radiation source (arc image vs laser) on observed ignition behavior. The pressure-dependent (< 21 atm) ignition domain of a PNC/MTN double base propellant is examined using controlled exposure lengths together with high speed movies and an infrared detector to monitor flame development. There is a brief flux-dependent period of transient flame development after gasification begins; this is followed by a relatively long, flux-dependent period of steady-state, radiation assisted burning before a selfsustaining condition is reached. The nature of this condition for self-sustainment is not yet well-defined. The ignition behavior seen with an arc furnace or a laser is generally quite close for both double base and composite propellants, if optical effects (reflection, penetration) are factored out. An exception is fast deradiation extinction, seen only with the laser; greater radiation penetration in the arc image wavelength region precludes this phenomenon. I. Introduction A S pointed out in the companion paper,l thermal zmradiation is a convenient energy input for studying solid propellant ignition behavior. By varying such factors as radiant flux, ambient pressure, and propellant compositions, much can be learned about the processes underlying the macroscopic ignition response, e.g., which of these factors controls that behavior in differing ambient conditions and what is needed to predict ignitability quantitatively in new circumstances. At the same time, one must be aware that the unique nature of radiation and the characteristics of the devices used to produce it can affect the test results. The present study is a systematic survey of radiation ignition behavior of a variety of propellants, intended to illustrate both these positive and negative aspects. In the companion paper,1 a generalized ignition behavior 4'map'* (log °f irradiation time vs log of radiant flux) was presented. The boundaries on this map were discerned by go/no-go testing and by monitoring of IR radiation from the developing flame. For clarity, we summarize them again here in the order they are encountered as irradiation time increases: Lla = first gas evolution; Llb = first IR signal from the surface region indicating the beginning of exothermicity; L]c = incipient flame indicated by a roughly 50-fold increase in IR signal; Lld = self -sustained flame indicated by steady burning if flux is removed; L2 = deradiation extinction boundary indicated by disappearance of a well-developed flame when radiation is removed too quickly. The companion paperl concentrated on certain propellant formulation effects; it illustrated how these boundaries are shifted strongly by the optical properties of the propellants. This was shown to obscure the comparison of different types of propellants, but unmodified double base propellants

Liquid propellant weapon system

Abstract: A gun and ammunition system utilizing a round of ammunition which contains a supply of liquid propellant and after ignition pumps this propellant into the combustion chamber of the gun.

Aerosol, spray-dispensing apparatus

Abstract: An aerosol, spray-dispensing apparatus comprising an outer, sealed container various neutral propellants are stored therein, an inner container having the lower portion thereof compressibly affected by the neutral propellant when the spray head of the spray valve is activated, the head and valve being attached to the outer, pressurized container in a normal manner, wherein the inner container includes an upper, non-collapsible, body member positioned within the pressurized container so as not to be affected by the internal pressure of the propellant gas stored therein. As arranged, the inner container provides a non-contaminated compartment wherein the active ingredient to be discharged is stored and sealed from the gas filled compartment of the outer container, whereby the pressure of the propellant gas therein will only collapse the lower, thin bag portion of the inner container, providing total discharge of the stored ingredient--be it in liquid or powder form.

Flame-Spreading and Combustion in Packed Beds of Propellant Grains

Abstract: This paper is concerned with the prediction of the pressure history during the process of flame-spreading and combustion of solid-propellant grains as would occur, for example in a gun cartridge. Solution of the governing conservation equations for the two-phase media requires the use of empirical relations to account for the physical processes of momentum and energy interaction between the solid grains and hot propellant gas. The results indicate the extreme importance of these interaction relations on the predictions of the pressure and velocity field. and at the other is a projectile which will begin to move at a given prescribed pressure. This '"piston" then moves through a long length of channel of the same cross section as the cham- ber, in order that the flow processes following piston motion can be followed. A predescribed igniter mass flow provides gaseous products which, in turn, ignite the bed. Since solid propellants have high burning rates, the rate of gas generation within the chamber is high. Therefore, the pressure is rising rapidly during this flame-spreading process. The pressure rises enhances the pressure-dependent burning rate of the propellant, the result of which is a rapidly accelerating combustion process, with generally steep gradients along the length of the chamber. This gradient results in a high-velocity flow of the gases toward the piston end and into the unburned portion of the propellant. Hence, the flame-spreading and pressurization is rapid, and the entire burn is completed in a matter of milliseconds, if the ignition source is strong enough. Looking at flow process taking place, one may determine the effect on the particle bed. The hot igniter gases initially are driven into a quiescent bed of propellant particles. These ignite the particles nearest the igniter source. The mass generation and subsequent pressurization occur, and a flowfield develops within the chamber. The propellant par- ticles exert a drag force on the flowing gases and are ac- celerated. As shot-start pressure is approached, the entire bed usually has been set into motion.J Throughout the burn, the particles continue to decrease in size as they burn. Kuo and Summerfield2 have pioneered the analysis of packed-bed solid-propellant combustion.

Method for making extruded, solventless, composite-modified double base propellant

Abstract: Solids loaded, extrudable, solventless, double-base propellants are formued by combining liquid plasticizers, solid binders, a high percentage of solid oxidizers, and fillers to yield propellants having high densities and capable of delivering high specific impulse.

Behavior of Aluminum in Solid Propellant Combustion.

Abstract: : The usefulness of powdered aluminum as a propellant ingredient is compromised by the details of its behavior in the combustion zone, its combustion in the motor volume, and by the nature of the product oxide droplets. This project was aimed at clarification of the mechanisms governing concentration, sintering and agglomeration of aluminum on the propellant burning surface, subsequent combustion of agglomerated aluminum, and resulting size distribution of the A1203 product droplets. The approach was to study the response of individual propellant ingredients, and combinations, to controlled heating in laboratory experiments such as hot stage microscope and hot plate apparatus.

Steerable extraction rocket

Abstract: A steerable rocket motor for towing a load or extracting an aircrew memberrom a disabled aircraft, regardless of aircarft attitude or altitude. The rocket motor is formed from a hollow cylindrical thin walled casing containing a high burn rate propellant and having a plurality of rocket nozzles at one end. The rocket nozzles are positioned around the circumference of the rocket body and are angled to thrust outward and toward the load or aircrew member being towed. A thrust control proportions thrust among the plurality of nozzles for controlling the pitch and yaw of the rocket. Position and rate sensing apparatus informs the thrust control regarding rocket attitude to enable the rocket to steer a predefined desirable flight trafectory. One or more lines are attached to the rocket and are adapted to be fastened to the load or aircrew member being towed.

Rapid-fire, fluid actuated B.B. gun

Abstract: A rapid-fire BB pellet-type machine gun operated from a source of gas propellant preferably a canister of liquefield gas, has a trigger-operated valve releasing propellant gas from the source to a pellet containing magazine for projecting the pellets in rapid succession through a barrel passageway to be ejected from the gun at high speed at a target to which the gun is pointed The pellets underlie and surround a sleeve in the magazine acting as a cofferdam to maintain a local level of the pellets below the gas inlet and the gas outlet so that the gas will impinge against and actuate the pellets causing them to be successively swept into the gas outlet for discharge through the barrel

Af terburning Predictions for Metal-Modified Propellant Motor Exhausts

Abstract: Predicted extents of afterburning in fuel-rich exhausts of metal-modified, double base propellant rocket motors have been investigated by means of a plume prediction code, which incorporates fully coupled turbulent kinetic energy boundary-layer and nonequilibrium chemical reaction schemes. The influences of a number of metals, including potassium, iron, molybdenum, tungsten, barium, tin, and chromium, on afterburning have been examined for a 300 N thrust motor. The effects of changes in total effluent mass flow rate and exit temperature were determined for both modified and unmodified propellants under static and flight conditions at sea level.

Holder to convert spray can into spray gun

Abstract: A universal spray can holder is longitudinally adjustable to securely hold an aerosol spray can and features an integral trigger mechanism to actuate the can valve. A built-in safety hood protects the spray can operator from missprayings, and from inhaling either can contents or can propellant.

Interior ballistics of a two-stage light gas gun using velocity interferometry

Abstract: An extensive interior ballistics study of a two-stage light gas gun was performed which resulted in a detailed measurement of the projectile velocity as a continuous function of time. The two-stage gun consisted of a 88.9-mm i.d. pump stage and a 28.6-mm i.d. launch stage. Five main parameters of gun operation, propellant mass, piston mass, pump gas, pump gas pressure, and projectile mass were varied in this study. Projectile velocities were measured using a very precise velocity interferometer for any reflecting surface (VISAR) technique. The measurements showed that the initial acceleration of the projectile is discontinuous due to the shock nature of the applied pressure on the projectile upon rupture of the burst diaphragm. These shock accelerations are understood easily via simple shock-tube theory. 9 figures, 3 tables.

Method for drying explosive materials

Abstract: Explosive materials such as gun powder and rocket propellants are dried safely by supplying the material in particulate form to a drying zone, passing the particulate material through the drying zone while agitating the material to cause the particles to move in random fashion, subjecting the particulate material to electromagnetic radiation to heat the moisture contained within the particles, maintaining a relatively cool gaseous atmosphere in the drying zone, and recovering the particulate material from the drying zone with the particles having a reduced moisture content and a temperature which is low as compared to the ignition temperature of the particles

Radial end burner rocket motor

Abstract: A rocket motor grain consisting of a one-piece solid base propellant divided into an aft end section having a central cavity extending throughout its length, a forward end section having a central longitudinal cavity filled with a propellant having a substantially higher burning rate than the base propellant and a central web section being defined between the forward and aft end sections. This radial end burning rocket motor grain provides a means for utilizing high energy and high density propellants which have high burning rates in a manner such that the burning rate effects can be offset to provide enhanced motor performance without the sacrifice of high energy. After initiation of the rocket motor grain, the aft end section and central web section begin burning together to provide the desired mass flow rate, followed by initiation of a higher burning rate propellant in the forward section. Thereafter, the higher burning rate propellant, being consumed at a much higher rate than the base propellant of the forward section, forms a cylindrical radial burning port therein, thereby extending the motor burn time.

Dimethyl hydantoin bonding agents in solid propellants

Abstract: A dimethyl hydantoin bonding agent is incorporated into a propellant systemo as to interact with and bond various filler materials into a cured binder system.

Initiator for use in laser beam ignition of solid propellants

Abstract: An initiator that produces an intermediate combustion step in a system forgniting solid rocket propellant with a laser beam. The initiator comprises a pyrotechnic pellet which has a concave conical surface and a breakaway/burn center section. The pellet is positioned in a container which has a window. A laser beam is directed through the window, onto the conical surface, and initiates combustion of the pellet. The container restrains the pellet from moving during combustion.

Gas generating charge for open chamber gas powered tool

Abstract: An ignitable charge for producing pressurized gas to power industrial tools; that is made of plentiful, common materials at a very low cost, lower in cost than conventional charges by orders of magnitude. The charge is comprised of a hollow plastic jacket of triangular cross section that is open through its center to both opposite ends and contains a nitrocellulose propellant in uncompressed, or expanded form that may be electrically ignited through one end of the jacket by a spark, hot wire, or the like in an open chambertype feed and firing mechanism. The charge produces pressurized gas at the desired burning rate and peak pressures for operating the tool.

Role of Gasphase Reactions During Radiant Ignition of Solid Propellants

Abstract: —A homogeneous propellant subjected to monochromatic radiant heating at the surface and in contact with an oxidizing gas is considered. Differential equations describing the conservation of species and energy in one dimension are solved numerically on a computer. The results indicate that though the gasphase reactions are important in establishing a gasphase flame, their influence in evaluating the ignition behaviour of the propellant can be conveniently neglected, at least for low heating rates and high pressures. Only at very low pressures and extremely high heating rates do the gasphase processess become important.

Solid Propellant Ignition and Other Unsteady Combustion Phenomena Induced by Radiation

Abstract: : Experimental and analytical investigations were conducted to understand the ignition and nonsteady burning processes that occur at and near the propellant surface, to determine the connection between the ignitability of a propellant and its other nonsteady combustion characteristics, to quantify the peculiarities of radiative ignition, and to develop a means of ranking propellant ignitability. As a result of these investigations, radiative ignition processes have been explained for a wide variety of propellant and test conditions. The stability properties of heterogeneous combustion waves were considered for linear and nonlinear situations. Nonlinear (large disturbances) solid propellant stability boundaries can be immediately defined from the knowledge of the associated restoring function. The restoring function is a property strictly dependent on the nature of the solid propellant.

Coating composition and method for improving propellant tear strength

Abstract: A typical rocket motor includes a motor casing containing a cast propellantonded to the casing and provided with a port through which combustion gases are delivered to the motor nozzle. During storage and operation, mechanical stresses in the propellant may produce tears resulting in motor malfunctions. Tear strength can be increased by reactively forming on selected port surface areas a thin-film cross-linked polymeric gel coating formed essentially of a highly functional polyglycol adipate and a polyfunctional isocyanate. Cross-linking with the propellant can be achieved by controlling the hydroxyl to isocyanate ratios of the coating and the propellant. The coating is particularly useful on XLDB (cross-linked, composite-modified double base) and on CMDB (composite-modified double-base) propellants.

Method of making a cartridge

Abstract: A method of making a cartridge, in particular a blank or propellant gas cartridge which has a casing of generally tubular form with a telescopically reverse in-folded star-crimp-closed integral tubular end section, and within which is contained a blank propellant powder charge, with a readily rupturable wad of low heat conductivity initial restraining mass formed between the propellant powder charge and the in-folded telescoping star-crimp-closed end of the casing, in which method the cartridge is formed by front loading a propellant charge and the low-heat-conductivity wad, and then star-crimping and telescopically reverse in-rolling the cartridge casing, after which the recessed in-rolled star-crimped casing is heat sealed.

Critical Review: Modeling of Acceleration Effects on Solid Propellant Combustion

Abstract: Acceleration fields normal and into burning solid propellant surfaces have been observed to cause marked increases, often time-dependent, in their regression rates. Models have been developed for prediction of this burning rate augmentation as a function of various parameters for metalized propellants and non-metalized composite propellants. Most of the metalized propellant models are invalid in that they assume a steady-state involving a finite number of metal agglomerates of constant size controlling the burning rate by formation of pits which lead the burning: in reality, such a steady-state cannot be achieved and flooding of the propellant surface with metal occurs. One model does present a reasonable approach to treating the transient behavior in a semiquantitative fashion, although the problem of calculating agglomerate size as a function of time and various independent parameters is not resolved. Two models of the interaction for nonmetalized propellants appear to be physically unrealistic.