11/28/2023 0 Comments Cube pro cartridge weight![]() Classification of grains according to their pressure-time characteristics.įIGURE 11-16. ![]() ![]() Sliver: Unburned propellant remaining (or lost-that is, expelled through the nozzle) at the time of web burnout (see sketch in Problem 11-6). Regressive Burning: Burn time during which thrust, pressure, and burning surface area decrease (see Fig. ![]() Progressive Burning: Burn time during which thrust, pressure, and burning surface area increase (see Fig. Perforation: The central cavity port or flow passage of a propellant grain its cross section may be a cylinder, a star shape, etc. Neutral Burning: Motor burn time during which thrust, pressure, and burning surface area remain approximately constant (see Fig. The shape or geometry of the initial burning surfaces of a grain as it is intended to operate in a motor.Ĭylindrical Grain: A grain in which the internal cross section is constant along the axis regardless of perforation shape, (see Fig. Stresses in these two types of grains are briefly discussed under structural design in the next section.ĭefinitions and terminology important to grains include:Ĭonfiguration. Today almost all larger motors and many tactical missile motors use case bonding. The case-bonded grains give a somewhat better performance, a little less inert mass (no holding device, support pads, and less insulation), a better volumetric loading fraction, are more highly stressed, and often somewhat more difficult and expensive to manufacture. They often have a lower cost and are easier to inspect. Cartridge-loaded grains are used in some small tactical missiles and a few medium-sized motors. Nozzle if the propellant grain has aged excessively. Simplified schematic diagrams of a free-standing (or cartridge-loaded) and a case-bonded grain. Free-standing grains can more easily be replacedįIGURE 11-14. In case-bonded grains the case is used as a mold and the propellant is cast directly into the case and is bonded to the case or case insulation. Cartridge-loaded or freestanding grains are manufactured separately from the case (by extrusion or by casting into a cylindrical mold or cartridge) and then loaded into or assembled into the case. There are two methods of holding the grain in the case, as seen in Fig. However, most rockets have a single grain. A few rocket motors have more than one grain inside a single case or chamber and very few grains have segments made of different propellant composition (e.g., to allow different burning rates). Once ignited, it will burn on all its exposed surfaces to form hot gases that are then exhausted through a nozzle. The propellant grain is a cast, molded, or extruded body and its appearance and feel is similar to that of hard rubber or plastic. The propellant material and geometrical configuration of the grain determine the motor performance characteristics. Should it not recognize either, the firmware or the detector might be broken.The grain is the shaped mass of processed solid propellant inside the rocket motor. Should the cartridge not be validated again but works on the ABS cartridges, the validation method might be broken on this cartridge. This should start the validation of the material, at which point you might get told that the colors don't match the print defined colors.
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