Self-igniting Fuel-oxidizer Systems and Hybrid Rockets

Abstract

<span style="font-size:14.0pt;line-height: 115%;font-family:" times="" new="" roman";mso-fareast-font-family:"times="" roman";="" color:black;mso-ansi-language:en-in;mso-fareast-language:en-in;mso-bidi-language:="" hi"="" lang="EN-IN">Fuel-oxidizer combinations capable of self-igniting simply on coming into mutual contact have been extensively used in bi-liquid rockets. In hybrid (solid fuel-liquid oxidizer) rockets too the self-igniting (hypergolic) propellant could be suited ideally. The relative non-existence of the hybrid rockets has been partly because of the paucity of suitable hypergolic solid fuels. The development of such fuels is hampered because of the lack of understanding of the chemical reactions occurring between the fuel and the oxidizer leading to ignition. The chemistry of these highly exothermic reactions occurring in submilliseconds in the pre-ignition stage is being studied for the past several years, in an effort to evolve suitable self-igniting systems. A major aspect of this work relates to, the solid N-N-bonded derivatives of hydrazines, which have been conceived as self-igniting fuels for the first time. Many of these compounds ignite readily, with short ignition delays on coming into contact with liquid oxidizers, like HNO₃ and N₂O₄. Polymeric resins having N-N bonds and reactive end-groups have been evolved to serve as fuel-binders for self-igniting compositions. This review narrates briefly the main highlights of the work carried out on hypergolic systems. A report on the hybrid rockets and their current status is also included.</span>