008, programy na windowsa, hack komputer, Anarchist Cookbook 2004, Additions

008

008, programy na windowsa, hack komputer, Anarchist Cookbook 2004, Additions

[ Pobierz całość w formacie PDF ]
.... Composite Rocket Fuels ....DISCLAIMER: The following file contains information of harmful or illegalnature. Neither the BBS or author providing this informationcan be considered responsible for the use of this file.The person using this knowledge is solely responsible forit's use or misuse. This file is intended to educate only.1.) IntroductionComposite propellants are solid rocket fuels that are composed of separatefuels and oxidizers mixed together in one homogenous mass. This propellantis then either molded into a grain to be inserted in an engine or cast in anengine casing and left to harden. The fuels and oxidizers taken separatelyare generally unreactive. Composite propellants are used in a number ofengines. There are engines that use water for fuel and an oxidizer, air foran oxidizer like a ramjet, and a liquid/solid engine that can be throttled.The rocket motors discussed here a best built by the amateur with propellantweights below 2 lbs. and preferably under 1 lb. This is still powerful enoughto shoot a sizable rocket to well over 4 miles altitude.Before I get into propellant mixtures a few terms to learn are:Specific Impulse - Defined as the impulse (force * time) delivered byburning a unit weight of propellant in a rocket engine.Volume Specific Impulse - The product of specific impulse and density. Thisis expressed in pound-seconds per cubic inch.If the propellant's weight is kept constant, apropellant with a lower Isp but a higher densitymay outperform one with a greater Isp but alower density.Specific Force - This is a measurement of the ability for a gas to performwork. Specific force (F) is expressed in foot-pound perpound.3.) OXIDIZERSComposite propellants contain both an oxidizer and a fuel. The oxidizer maybe a monopropellant and as such contributes power to the propellant mix.The ideal oxidizer should decompose into totally gaseous exhaust.Oxidizers used in composite propellants : Potassium perchlorate (KClO4).Potassium pechlorate was one of the first used oxidizers. One of it's draw-backs is the product of decomposition ( potasium chloride ) is not a gas atregular temperatures and does not contribute as a working gas. The KClappears as a dense smoke in the rockets exhaust. Burning rates of propellantsmade with KClO4 are usually high at 0.8 - 0.9 in/sec at 1000 PSI. Densitiesof fuels made with KClO4 also tend to high at 1.8 - 2.0 gm/cc. Specificimpulses are usually below 200 lb-sec/lb. Potassium perchlorate is hardlyever used im modern propellants.Ammonium Perchlorate NH4ClO4. This is the oxidizer of choice when possible.The products of diassociation of NH4ClO4 are 100% gas. The specific impulseof propellants using this oxidizer reaches 250 lb-sec/lb. Depending on thepercentage of NH4ClO4 the burning rate may reach or exceed 0.5 in/sec. Theproducts of exhaust are N2, CO, CO2, H2, H2O, and HCl. The HCl may pose someproblem if the engine is used in high humidity as the HCl vapor may formvisible hydrochloric acid fumes.Ammonium Nitrate NH4NO3. This oxidizer is useful as it is usually availablein bulk weight. The products of disassociation of NH4NO3 are 100% gas. How-ever the temperatures produced by the propellant are low. For this reason,thespecific impulse of NH4NO3 propellants are usually no greater than 180 lb-sec/lb and low percentage propellants have an Isp of 75 lb-sec/lb. The productsof exhaust of NH4NO3 propellants are N2, CO, CO2, H2, H2O. These gases causeno special problems. The burning rate of NH4NO3 Propellants are low, rangingfrom 0.05 in/sec to 0.27 in/sec. The higher burning rates are possible ifcatalysts are used in the propellant. Prussian blue, chromium compounds(ammonium dichromate), or cobalt compounds are catalysts that are used.Ammonium nitrate is hygroscopic and undergoes a phase change if the temper-ature goes above 90 deg./F. Because of this phase change, some grains maycrack if the temperature cycles about this temperature. The burning temper-ature of NH4NO3 propellants are lower than any other propellants especiallyat low percentages of oxidizer.Lithium Perchorate LiClO4. Some work has been done using lithium perchlorateas an oxidizer. The lithium chloride formed in the exhaust is a gas at hightemperatures. Lithium salts are hygroscopic and must be protected from highhumidity. Burning rates of LiClO4 propellants are similar to KClO4 mixtures.4.) FUELSFuels Used in Composite Propellants : Since most rubbers and polymers are notavailable to the general public, some adjustments have to be made. A goodsource of plastics is an auto supply store. There you can find epoxy resinwhich can be used as a fuel. You will also find fiberglass resin. This is aliquid made from polystyrene and polyester resin. It is catalyzed with a fewdrops of hardener. PVC plastic can be dissolved in tetrahydofuran to makea thick paste. This can be mixed with an oxidizer and allowed to dry for anextended time to form a propellant grain. Asphalt was used in some JATO unitsabout 30 years ago but it was found lacking when used at high temperatures.Some fuels used in commercial engines are polyurethane rubber, polysulfiderubber, and butadiene-acrylic acid. Non ferrous metals are added to propell-ants to increase the temperature of combustion and consequently the Isp. Themetals most used are aluminum, magnesium, and copper. The metals are usuallyadded in amounts of 5% - 25%. In engines designed to breath water as an oxid-izer, metal amounts to about 50% to 80% of the weight of the propellant. Theother components are usually ammonium perchlorate and a polymer.Propellant Grain Geometry : If the grain is ignited from end on, like acandle burns, the thrust will be steady or neutral. If the grain has a holein it extending end to end and the combustion takes place from the inside outthen the thrust will rise to a peak or be progressive. This is because thesurface area of the grain becomes greater as it burns whereas in a neutralgrain the surface area remains the same. A cruciform shaped grain produces alarge amount of thrust first then tapers off because the surface area becomessmaller. If the grain is tubular and the combustion takes place from both theinside out and the outside in, then the thrust will be neutral but fastburning.Wherever you wish the grain not to burn, it must be coated with a retardent.Epoxy works well as a retardent as does Elmers white glue. At least two coatsof retardent should be used. An epoxy retardent can be used to retain a grainin a rocket engine. When tubular grains are used, the igniter is usually puttowards the nose of the rocket and fires backwards towards the nozzle. Thisinsures the grain is ignited completely.Inspect the propellant grain for any cracks or imperfections. A crack cancause the surface area of the propellant to increase astronomically. This cancause an explosion because of the increased pressure.5.) PROPELLANT MIXTURESThe ratios of oxidizers and fuels depends on the type of engine desired. Theamount of oxidizer can be as high as 90% as in some ammonium nitrate mixes toas little as 20% ammonium perchlorate as in some water breathing engines.A fast burning mixture: Potassium Perchlorate 20%Isp=200 Ammonium Perchlorate 55%Epoxy Resin/Hardener 17%Powdered Aluminum 8%This is very fast burning but the exhaust makes a fairly heavy smoke.A slow burning propellant. Great for sustainer engines.Isp=165 Ammonium Nitrate 70%Ammonium Perchlorate 10%Polyester Resin 18%Powdered Charcoal 2%Not very powerful but useful. The charcoal helps keep the combustion steady.A very powerful mixture: Ammonium Perchlorate 75%Isp=250 Powdered Aluminum 10%PVC in THF 15%All the ingredients should be dampened with THF (tetrahydrofuran) beforemixing. Do this in an area with very good ventilation and wear rubber glovesto keep from contacting the THF with bare skin. This mixture is best used ina perforated grain to help the solvent evaporate.An ammonium nitrate based propellant: Ammonium Nitrate 70%Isp=160 Powdered Aluminum 5%Polyester Resin 18%Ammonium Bichromate 5%Powdered Charcoal 2%A good mix when perchlorates are not available.Do not under any circumstances use chlorates for rocket propellants. You willnot make a rocket, just a pipe bomb with fins.6.) COMPOUNDING PROPELLANTSOne thing to keep in mind when making a propellant, the volume of fuel/binderto volume of oxidizer and additives must not be too low. If it is then themixture will be too dry to mix well. It will also hurt the strength of thegrain. You may have to cut down on the amount of oxidizer depending on thefuel you are using.For rockets weighing 1 pound and less the... [ Pobierz całość w formacie PDF ]

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