Bipropellants

Bipolar plates, MCFC, 12 223 Bipolar transistors, silicon based semiconductors in, 22 246-249 Bipolymers, 20 533, 534 Bipropellants, 10 727 Bipyridines, uses for, 21 127 Bipyridinium herbicides, 13 315 Bipyridium, 24 51 Bipyridyl trimers, 24 50 Biquinolines, 21 200 Birefringence, 14 675, 680 19 745 in ferroelectric crystals, 11 94 polycarbonate, 19 822 of regenerated cellulose fibers,... 

Frankel and co-workers prepared a series of alkyl diazides from the reaction of dihaloalka-nes with sodium azide in DMF at 95 °C, including 1,3-diazidopropane, 1,4-diazidobutane and l,3-diazido-2,2-dimethylpropane. Tris(azidomethyl)amine, an energetic fuel with potential for use in bipropellant propulsion systems, is synthesized from the reaction of tris(chloroethyl)amine with sodium azide." ... 

Propellants used during WWII were usually liquid bipropellants, consisting of gasoline, aromatic amines and alcohol as combustibles with oxidants, such as liquid oxygen, hydrogen... 

A. Iwama K. Yamazaki, Effect of Some Parameters on the Ignition Delay of Hyper-golic Bipropellants. I. The Variation With Liquid Temperature, Oxidant Concentration, Subatmos-pheric Pressure and Fuel Composition , KKZ 63, 1879-83 (1960) CA 57, 1140(1962)... 

R.W. Jenkins R.E. Elbel, Performance potential of the bipropellant pulsed turbine space power system, AdvEnergyConservEng, PapCritSumlntersocEhergyConversEngCont 1967, 493, AmSocMechEng, NY CA 71,... 

The requirements for selecting a fuel and oxidizer as a liquid bipropellant system are usually a compromise between the demands of the vehicle system, the propulsion system, and the propellants themselves. The vehicle and propulsion system will determine performance levels, physical property requirements, thermal requirements, auxiliary combustion requirements, degree of storability and package-ability, hypergolicity, etc. The final propellant selection must not only satisfy such requirements but is also dictated by thermochemical demands which the fuel and oxidizer make on each other. Frequently, specifically required properties are achieved through the use of chemical additives and/or propellant blending. 

As a result of this constant evaluation and compromise between the demands of the vehicle and propulsion systems and the current propellant technology, various liquid propellant systems have been developed and are being applied in current vehicle systems (Table IV). In Table IV thrust level is used to demonstrate the size of the propulsion system. Some of the systems in this table have been phased out, while others are still in development. However, Table IV does represent the current status of operational liquid bipropellant systems. 

Nitroparaffins. Nitro-organics as a class of compounds are of greater interest in solid than liquid propellants. However, some nitroparaffins have been utilized in liquid systems. Nitromethane has been used as a monopropellant, while tetranitromethane, hexanitroethane, nitroform, and nitroform salts have been considered as oxidizing components in bipropellant systems. The high melting points of the latter and their sensitivity restrict their use to solutes in lower freezing, insensitive liquids. A solution of 70 wt. % C(N02)4 in N204 is an example of such a system and has been proposed as an oxidizer (3). 

The use of a heterogeneous fuel, in which the metal compound is suspended in a liquid fuel, avoids a third storage vessel because it is used with the oxidizer as in a conventional bipropellant system. The technical problems are then associated only with the stabilization of the suspension, with the rheological properties of the stabilized fuel, and with the reactivity of the suspended solid with its carrier. 

As shown in Figure 4.1, liquid propellants are further classified as mono- or bipropellants. The monopropellants are liquids which undergo controlled exothermic decomposition or combustion reactions in the absence of external oxygen. They have comparatively low energy and low specific impulse (Isp) and are used in... 

Nitromethane (Vol. I, p. 579) may be used as a monergol propellant. However its negative oxygen balance may be reduced by the addition of liquid oxidants, e.g. of tetranitromethane to form a bipropellant. In practice, however, nitromethane decomposes too slowly, and it is difficult therefore to obtain hypergolic mixtures from it. To facilitate and accelerate the decomposition of mixtures with nitromethane it is necessary to add a catalyst, such as a salt of chromic acid. 

Bipropellants consist of two components, a fuel and an oxidizer, which are stored in separate tanks and injected into a combustion... 

Table 8.4 Performance of some liquid rocket bipropellants...

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