Rocket propellants with fuels

Nitromethane is active chemically, can have many chemical reactions as a chemical reagent or synthesis intermediate. It also can be used as solvents for cellulose nitrate, cellulose acetate, cellulose acetate, vinyl resin, polyacrylate coating, beeswax, etc. base or other materials can be added into nitromethane for generate explosives when nitromethane is mixed with strong oxidant hydrogen peroxide or N2O4, it can be used as liquid rocket propellants and fuel nitromethane can also be used in medicine, dyes, insecticides, fungicides, stabilizers and surfactants. 

Polymer-based rocket propellants are generally referred to as composite propellants, and often identified by the elastomer used, eg, urethane propellants or carboxy- (CTPB) or hydroxy- (HTPB) terrninated polybutadiene propellants. The cross-linked polymers act as a viscoelastic matrix to provide mechanical strength, and as a fuel to react with the oxidizers present. Ammonium perchlorate and ammonium nitrate are the most common oxidizers used nitramines such as HMX or RDX may be added to react with the fuels and increase the impulse produced. Many other substances may be added including metallic fuels, plasticizers, stabilizers, catalysts, ballistic modifiers, and bonding agents. Typical components are Hsted in Table 1. 

Although modern chemistry allows development of even more effective rocket propellants, energy efficiency is not the only consideration factor. For example, fluorine and its derivatives arc better oxidizers than oxygen, but their extreme toxicity make them environmentally dangerous. The same concerns prevent the use of beryllium hydride—an excellent fuel that combines high density with the energy efficiency comparable to liquid hydrogen. 

The third type of propellent explosive, the composite type, is a more recent development, the purpose of which is to provide rocket propellants of increased thrust, compared with the ordinary varieties. Composite propellants are based on an oxidising solid, commonly a perchlorate, together with an organic binder which both acts as fuel and gives adequate mechanical strength to the mixture. The search for even more energetic compositions continues, but because of the military importance of the... 

Cyanogen, a colorless gas with an almond-like odor, is used in organic syntheses, as a fumigant, as a fuel gas for welding and cutting heat-resistant metals, and as a rocket and missile propellant with ozone or... 

Combustion of powdered aluminum with steam is a potentially attractive propulsion system for torpedoes, because of the very high-energy density (energy per unit volume) that can be achieved. Since the oxidizer can be taken from the environment, on-board storage is required only for the aluminum propellant. A study of potential torpedo propellant/oxidizer combinations including Al, Zr, Mg, and Li metals, hydrocarbon fuels, and typical solid rocket propellants, and... 

Since rocket propellants are composed of oxidizers and fuels, the specific impulseis essenhally determined by the stoichiometry of these chemical ingredients. Ni-tramines such as RDX and HMX are high-energy materials and no oxidizers or fuels are required to gain further increased specific impulse. AP composite propellants composed of AP particles and a polymeric binder are formulated so as to make the mixture ratio as close as possible to their stoichiometric ratio. As shown in Fig. 4.14, the maximum is obtained at about p(0.89), with the remaining fraction being HTPB used as a fuel component. 

Fig. 12.11 shows the structure of a rocket plume generated downstream of a rocket nozzle. The plume consists of a primary flame and a secondary flame.Fil The primary flame is generated by the exhaust combustion gas from the rocket motor without any effect of the ambient atmosphere. The primary flame is composed of oblique shock waves and expansion waves as a result of interaction with the ambient pressure. The structure is dependent on the expansion ratio of the nozzle, as described in Appendix C. Therefore, no diffusional mixing with ambient air occurs in the primary flame. The secondary flame is generated by mixing of the exhaust gas from the nozzle with the ambient air. The dimensions of the secondary flame are dependent not only on the combustion gas expelled from the exhaust nozzle, but also on the expansion ratio of the nozzle. A nitropolymer propellant composed of nc(0-466), ng(0-369), dep(0104), ec(0 029), and pbst(0.032) is used as a reference propellant to determine the effect of plume suppression. The burning rate characteristics of the propellants are shown in Fig. 6-31. Since the nitropolymer propellant is fuel-rich, the exhaust gas forms a combustible gaseous mixture with the ambient air. This gaseous mixture is ignited and afterburning occurs somewhat downstream of the nozzle exit. The major combustion products in the combustion chamber are CO, Hj, CO2, N2, and HjO. The fuel components are CO and H2, the mole fractions of which at the nozzle throat are co(0.47) and iH2(0.24).

Though the pyrolants used in gas-hybrid rockets burn in a similar manner as rocket propellants, their chemical compositions are fuel-rich. The pyrolants burn incompletely and the combustion temperature is below about 1000 K. When an atomized oxidizer is mixed with the fuel-rich gas in the secondary combustor, the mixture reacts to generate high-temperature combustion products. The combushon performance designated by specific impulse, is dependent on the combinahon of pyrolant and oxidizer. 

Tq, of gas-generating pyrolants such as fuel-rich AP-HTPB and fuel-rich nitropoly-mer pyrolants are lower than those of rocket propellants such as AP-HTPB and nitropolymer propellants. The gas-phase temperature is low and hence the heat flux feedback through the wires is low for the gas-generating pyrolants as compared with propellants. However, r /ro appears to be approximately the same for both pyrolants and propellants. The obtained burning-rate augmentations are of the order of 2-5. 

Misch metal, an alloy of cerium with other lanthanides is a pyrophoric substance and is used to make gas lighters and ignition devices. Some other applications of the metal or its alloys are in solid state devices rocket propellant compositions as getter in vacuum tubes and as a diluent for plutonium in nuclear fuel. 

Hybrid Rocket Propellants. A special proplnt combination of unlike materials, particularly of unlike physical characteristics. Typical hybrid proplnt combinations are a solid fuel (or oxidizer) in combination with a liquid oxidizer (or fuel) in tjiat order. Sometimes a grain of solid fuel is encased in the combustion chamber of a rocket engine and burned in combination with liq oxygen. Similarly, a liq fuel may be injected into a combustion chamber in contact with a solid oxidizer. Another example is the use of concentrated hydrogen peroxide and a hydrocarbon fuel. In this case, the hydrogen peroxide is converted by decompn into a hot gas contg oxygen. The fuel is injected downstream of the first reaction, mixed with the hot oxidizer-rich gas, and burns (Ref 1)... 

In organizing the symposium, we made the usual division into solid and liquid rocket propellants. Most readers no doubt already know the relative merits of solid vs. liquid systems—viz., the instant readiness of solids (compared with cryogenic liquids), their higher density (important in volume-limited systems), and the relative simplicity of rocket construction liquids offer easy variation in thrust level and the attainment of higher specific impulses, the latter because physical separation permits the use of fuels and oxidizers that would be incompatible if premixed. 

Composite rocket propellants are two-phase mixtures comprising a crystalline oxidizer in a polymeric fuel/binder matrix. The oxidizer is a finely-dispersed powder of ammonium perchlorate which is suspended in a fuel. The fuel is a plasticized polymeric material which may have rubbery properties (i.e. hydroxy-terminated polybutadiene crosslinked with a diisocyanate) or plastic properties (i.e. polycaprolactone). Composite rocket propellants can be either extruded or cast depending on the type of fuel employed. For composite propellants which are plastic in nature, the technique of extrusion is employed, whereas for composite propellants which are rubbery, cast or extruded techniques are used. 

It has been used as a solvent and as an intermediate in the manuf of chemicals used in the expl industry and of synthetic rubber (Ref 4). During WWII, acetal(as well as acetaldehyde) was used in Germany as hyper-gollic fuel in liquid rocket propellants in conjunction with red or white fuming nitric acid which served as an oxidizer. Acetal was later replaced by ca te ch o 1( Bren zc ate chin or Brenzol in Ger)(Ref 10)... 

Acetaldeiiyde(as well as acetal) was used during WVFII in Germany as a hypergolic(qvl) fuel in liquid rocket propellants in conjunction with oxidizers, red or white coned nitric acids. These fuels were later replaced by catechol(BrenzcatechoI or Brenzol, in Ger)... 

Aluminum Dust in Rocket Propellants. The possibility of using Al dust as a fuel ingredient of rocket propellants was investigated by Stettbacher. The dust, was mixed with liq hydrocarbons such as benz, mineral Oil, etc, and liq oxygen was added as an oxidizer. 

A mixt of hydrocarbons obtd from the second portion of the fractional distillates, betw 70-90°, of crude petroleum. It is a clear col liq of d 0.640 -0.675 insol in w but miscible with ale, eth, oils and carbon disulfide(Ref 1). This mixt is considered by Sax(Ref 3) to be si toxic but dangerous whqn exposed to heat or flame. This mixt should not be confused with benzene or benzene homo-logues. It can be used as an insecticide and as a solv for some expls. The Germans used it during WW II as one of the fuels(together with O as oxidizer) for propelling the missile of WWII called V-l(Ref 4). Benzine with A1 dust and liq O as oxidizer was proposed by Stettbacher(Ref 2) as a rocket propellant... 

PATR 1637(1947XBurning and other characteristics of stick rocket proplnts) 6)S.S.Penner, JApplPhys 19, 392-8(1948) CA 42, 6512(1948)(Effect of radiation on rate of burning of solid fuel rocket proplnts) 7)L.H.Eriksen, Investigation of Asphalt-Perchlorate and Resin-Perchlorate Rocket Propellants , PATR 1676(1948) 8)S.S.Penner, JApplPhys 19, 511-13(1948) CA 42, 8475(1948) (The theory that burning rates of rocket proplnts increase slightly with an increase in radiation path length was verified experimentally for two double-base rocket proplnts) 9)W.G.Thummel,... 

---