Rocket propellants bipropellant

Liquid rocket propellants are subdivided into monopropellants and bipropellants. Monopropellants are liquids which burn in the absence of external oxygen. They have comparatively low energy and specific impulse and are used in small missiles which require low thrust. Hydrazine is currently the most widely used monopropellant however, hydrogen peroxide, ethylene oxide, isopropyl nitrate and nitromethane have all been considered or used as monopropellants. Information on the performance of some monopropellants is presented in Table 8.3. 

For liquid rocket propellants, there is a difference between mono and bipropellants. Monopropellants are endothermic liquids (e.g. hydrazine), which decompose exothermically - mainly catalytically (e.g. Shell-405 Ir/Al203) - in the absence of oxygen ... 

Traditionally the liquid systems are considered to be either bipropellants or mono-propellants although as discussed in later sections multicomponent systems are feasible. The most common liquid systems are the bipropellant ones in which the fuel and oxidizer are introduced separately into the rocket combustion chamber. 

The advantages of a monopropellant over a bipropellant combination result primarily from a substantial reduction in the number of components in the tankage and flow hardware. The attractive simplications in the propulsion system resulting from the use of monopropellants are obtained only at the expense of a reduced specific impulse. The resulting implied trade-off between simplicity and propellant performance limits the attractiveness of monopropellants to propulsion systems where a simplicity and the usually associated reliability which comes with simplicity are premium desired characteristics. Typical applications have included attitude control rockets, vernier rockets for mid-course trajectory corrections, and other low thrust propulsors, especially those having a requirement for pulsed operation or repeated restarts. Monopropellants also find application as a source of relatively low temperature working fluids, as for driving gas turbines. 

Applications. To date, the liquid propellant systems used in chemical propulsion range from a small trajectory control thruster with only 0.2 lbf (0.89 N) thrust for orbital station-keeping to large booster rocket engines with over l. 0 million lbf (4.44 MN) thrust. Bipropellant propulsion systems are the most extensively used type today for... 

Small-orifice injectors are used to atomize and mix the liquid propellants in appropriate proportions. The propellants enter the thrust chamber through the injection manifold and bum inside the thrust chamber. A typical liquid bipropellant rocket engine is shown in Fig. 37.20. 

In the field of propellants and explosives, studies have been made of the detonation properties of potassium dinitrobenzofuroxan 493,535 and the corresponding barium salt,492 of 3-methyl-4-nitrofuroxan,127 of benzo-trifuroxan,129,130 and of dicyanofuroxan.128,134 This last compound is used in preparing a hypergolic bipropellant system,536 and as a constituent, with tetrazole polymers, of solid fuels for rocket propulsion.537... 

Moreover, there is a current need of miniaturized propulsion system for widening the capabilities of low cost micro-satellites. Recently, the development of a turbo-pump fed miniature rocket engine has been proposed as a new propulsion system for micro-satellites (10 to 100 kg) [6] the bipropellant tlmister uses 70 wt.-% H2O2 as oxidizer and ethanol as fuel. The engine displays four sub-components (i) two propellant micro-pumps, (ii) a HP decomposition chamber, (iii) a turbine coupled to an electric power generator and driven by the hot gas released from HP decomposition, and (iv) a thruster for the combustion reaction. 

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