Hypergols

Article containing a secondary detonatng explosive substance, without means of initiation and with a propelling charge (other than a charge containing a flammable or hypergolic liquid) E... 

Hypergolic A hypergolic mixture ignites upon contact of the components without any external source of ignition (heat or flame). The only field, in which this is a desirable event, is in rocket fuel research. Accidental mixing of incompatible materials can lead to a fire or explosion. Here is one example provided by the staff at ILPI of what can happen, when incompatibles are mixed. Always read the labels on your bottles (don t assume a chemical s identity by the shape, size, or color of the bottle), and know what materials are incompatible with the chemicals that you are using. 

The gas has no practical application as an expl. It is of importance, however, as an additive to N204 to depress the fr p of this biproplnt hypergolic oxidizer (Ref 7). It is also... 

L34-R to L44-R Hypergolic Propellants in Vol 7, H254-L to H259-R Nitrogen Determination in Energetic Materials, and Mass Spectrometry in this Vol... 

Hypergolic reaction systems have been proposed (Refs 46 73) for 5.56mm ammo, specifically triethylaluminum (TEA) together with inorganic oxidizers. This system is self-igniting in air, but is compatible with some nitrates, chlorates and perchlorates... 

To describe hypergolic heating, Anderson and Brown (A10) proposed a theoretical model based upon spontaneous exothermic heterogeneous reactions between the reactive oxidizer and a condensed phase at the gas-solid interface. In these studies, the least complex case was considered, i.e., the one in which the solid phase is instantaneously exposed to a stagnant (nonflowing) gaseous oxidizer environment. This situation can be achieved experimentally provided the sample to be tested is suddenly injected into the desired environment in a manner designed to minimize gas flow. 

Parametric studies showed that mass diffusion in the gas phase could be neglected under most conditions. The calculations also show that the selection of the hypergolic combination (i.e., the gaseous oxidizer and the propellant system) fixes all of the parameters except the initial temperature and the oxidizer concentration. A general solution of the model shows that the ignition-delay time is approximately rated to the gaseous oxidizer concentration by the relation... 

There are a variety of igniter designs which are currently employed in solid-propellant rockets. These types include rocket-exhaust (pyrogen), pyrotechnic, and hypergolic igniters, each of which can be located in the head-end closure of the motor or in the exhaust nozzle at the aft-end of the motor. The heat-transfer information appropriate to each of these possible combinations is discussed in the following sections. 

Fig. 10. Ignition delay as a function of mass-flow rate from hypergolic igniter at an initial pressure of 1 atm (B8, F6). 

Igniter(s) design, 21-24 pyrotechnic, 23-24 rocket exhaust, 21-23 aft end, 23, 28 heat end, 21-23 Ignition approaches kinetic, 9 thermodynamic, 9 chamber-pressure transient, 7-8 delay time, 20, 24-25 hot-wire, 11-12 hypergolic, 24 pressure transients, 29-30 theory... 

A powerful reducing agent and fuel, hypergolic with many oxidants such as dinitrogen tetraoxide or hydrogen peroxide. 

Noble, P. et al., Am. Inst. Aeron. Astronaut. J.. 1963,1, 395-397 Hexanitroethane is a powerful oxidant and hypergolic with dimethylhydrazine or other strong organic bases. 

Mixtures with triethylaluminium have been used as hypergolic igniters in rocket propulsion systems. 

It is hypergolic with fluorine or fuming nitric acid, and explodes with ozone. 

Chlorine trifluoride is a hypergolic oxidiser with recognised fuels, and contact with the materials following at ambient or slightly elevated temperatures is violent, ignition often occurring. The state of subdivision may affect the results. 

Antimony, arsenic, selenium, tellurium, iridium, iron, molybdenum, osmium, potassium, rhodium, tungsten (and when primed with charcoal,) aluminium, copper, lead, magnesium, silver, tin, zinc. Interaction of lithium or calcium with chlorine tri- or penta-fluorides is hypergolic and particularly energetic. 

Oxidation of alkanethiols to alkanesulfonic acids with excess cone, acid as usually described is potentially hazardous, the exotherm often causing ignition of the thiol. A modified method involving oxidation under nitrogen and at temperatures 1-2 C above the m.p. of the thiol is safer and gives purer products [1]. Technical butanethiol (containing 28% of propane- and 7% of pentane-thiols) is hypergolic with 96% acid [2], Oxidation of several thiols to the sulfonic acids by addition to stirred cone, acid had been effected normally, but when 2 new... 

Although aniline may be hypergolic with nitric acid (below), anilinium nitrate dissolves unchanged in 98% acid and can be stored for long periods, though the solution has explosive properties. 

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