Hypergolic systems

Ammonia. Lewis, Pease and H. S. Taylor [19] and Altman and Penner [20] showed that the system liquid ammonia-nitric acid may be transformed into a hypergolic system by the addition of an alkali metal, e.g. lithium, to the ammonia. 

A fuel cell utilizing UDMH as fuel and N02 as oxidant is reported. Operated intermittently over a 3-month period with degradation, it consistently produced a power density of 40mw/ cm2 (40w/ft2). The cell consists of a sandwich of Zr acid phosphate in a polyvinylidene fluoride (PVF) binder and diffuse-catalyst layers of Pt black, Zr acid phosphate and PVF. Pt screens are used as current collectors] 3) G.R. Eske-lund et al, Chemical-Mechanical Mine , PATR 3724 (1968) [A mine feasibility study is reported in which the hypergolic system UDMH—... 

C apener [9] and other sources [7, 2 ] give a wide list of hypergolic systems which can be summaiized as follows ... 

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... 

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... 

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

M. Kilpatrick L.L. Baker, Jr, A study of fast reactions in fuel-oxidant systems, FifthSymp Comb, Reinhold, NY, (1955) 26) S.A. Masier et al, Hypergolic ignition of light hydrocarbon fuels with fluorine-oxygen (FLOX) mixtures, ... 

In what follows we will briefly describe the various types of jet propulsion systems and give a list of references to the voluminous literature that has appeared on this subject since the publication of the above book (1959). The reader is also referred to the following Encyclopedia articles Combustion Hypergolic Propellants Ignition Propellants and Rockets... 

Rockets. As clearly stated a rocket is differentiated from a fluid flow engine in that a rocket generates its thrust entirely from reacting material carried within it, while a fluid flow system takes in material (air) from the outside. The subject of rockets will be described in more detail under Rockets and some material pertaining to rockets has already been described under Hypergolic Propellants and under Ignition. Here we just outline the type of rockets in use or under development ... 

Vast numbers of fuels may be combined with the above oxidizers to form biproplnts. Many hypergolic biproplnt systems are listed in this Vol, pp H254-L to H259-R, under Hypergolic Propellants. The foregoing tabulation (Table 72, p 317 of Ref 23) lists several common biproplnts... 

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. 

Upper stage propellant applications are usually based primarily on performance—i.e., high specific impulse. If the upper stage is a multistart vehicle, hypergolicity is usually required. Careful consideration is also given to the propellant physical and chemical stability as well as to the matching of the propellant s liquidus range to the space environmental temperature if the propellant system is to remain operational in space... 

Military applications can be subdivided into two distinct types— fixed launch site systems and mobile systems. Both types place emphasis on specific impulse, density impulse, excellent storability and stability, and instant readiness. Fixed-site systems, which include most of the long range ballistic missiles, are systems whose launch facilities are well established and are usually environmentally controlled. These vehicles are usually pump fed and regeneratively cooled. Hypergolicity is preferred, but not necessarily required. 

Thompson, D.M. (2000) Tertiary amine azides in hypergolic liquid or gel fuels propellant systems. US Patent 6,013,143. 

---