| || Spontaneously Igniting Hybrid Fuel Oxidiser Systems
Author : Jain, S.R.
Source : Defence Science Journal ; Vol:45(1) ; 1995 ; pp 5-16
Subject : 629.76 Rockets and Missiles ;620.1 Material Science and Technology
Keywords : Thermal decomposition ;Rocket performance parameters;Hybrid rockets ;Solid fuel liquid oxidiser systems;N N bonded compounds;Liquid oxidisers;Hypergolic ignition
Abstract : After briefly outlining the recent developments in hybrid rockets, the work carried out by the author on self-igniting (hypergolic) solid fuel-liquid oxidiser systems has been reviewed. A major aspect relates to the solid derivatives of hydrazines, which have been conceived as fuels for hybrid rockets. Many of these N-N bonded compounds ignite readily, with very short ignition delays, on coming into contact with liquid oxidisers, like HNO/sub 3/ and N/sub 2/ O/sub 4/. The ignition characteristics have been examined as a function of the nature of the functional group in the fuel molecule, in an attempt to establish a basis for the hypergolic ignition in terms of chemical reactivity of the fuel-oxidiser combination. Important chemical reactions occurring in the pre-ignition stage have been identified by examining the quenched reaction products. Hybrid systems exhibiting synergistic hypergolicity in the presence of metal powders have investigated. An estimation of the rocket performance parameters, experimental determination of the heats of combustion in HNO/sub 3/, thermal decomposition characteristics, temperature profile by thin film thermometry and product identification by the rapid scan FT-IR, are among the other relevant studies made on these systems. A significant recent development has been the synthesis of new N-N bonded viscous binders, capable of rataining the hypergolicity of the fuel powders embedded therein as well as providing the required mechanical strength to the grain. Several of these resins have been characterised. Metallised fuel composites of these resins having high loading of magnesium are found to have short ignition delays and high performance parameters.
| || Ignition Delay Studies on Hypergolic Fuel Grains
Author : Jain, S.R.;Murthy, K.N.;Thanoo, B.C.
Source : Defence Science Journal ; Vol:38(3) ; 1988 ; pp 273-286
Subject : 629.7 Aeronautics
Keywords : Hypergolic fuel compositions;Polymeric binders;Short ignition delays;Hypergolic fuels;Fuel grain composition
Abstract : The ignition delays of several solid hypergolic fuel compositions, casted using various polymeric binders, or as melts, have been determined with fuming nitric acid as oxidizer. The ignition delays of various hypergolic fuel compositions increase drastically drastically on casting with binders like, carboxyl or hydroxyl terminated polybutadiene. Fuel grains cast using some newly synthesised epoxy resins with other ingredients. Such as curing agent, magnesium powder and fuel, have shor ignition delays of the order of 200 ms, and also mechanical strenght. Increasing the amount of binder in the composition retards the hypergolicity of the rain. Similar studies have been made on melt-cast systems using low melting hypergolic fuels for casting fuel powders. The ignition delays of the melt-cast grains are longer than those determined taking the composition in the powder form. The effect of highly hypergolic additives, and metal powders, on the ignition delay of the cast compositions has been determined. Grains having good mechanical strength and short ignition delays have been obtained by optimising the fuel grain composition.