IRFNA

IRFNA (b)/UDMH (c) AJ10-118 7500 Space booster (Delta 2nd stage)... 

IRFNA (b)/JP-4 (a). Aerobee 100 sustainer 2600 (total) . Sounding rocket... 

Radiomic a) RP-1, JP-4 JP-5 Kerosene Fractions b) IRFNA Inhibited Red Fuming Nitric Acid c) UDMH Unsym Dimethyl Hydrazine 85-100 General purpose attitude control... 

IRFNA (inhibited red fuming nitric acid) 84.4% HNOa-14% N204— 1% H2O-0.6% HF... 

The extensive application of N204 in pure form to rocketry is a fairly recent development however, its use as a stabilizer and freezing point depressant for HN03 dates back more than 15 years. Mixtures of HN03, N204, and small amounts of water and HF are referred to as inhibited red fuming nitric acid (IRFNA) or without the HF (a corrosion inhibitor) as merely red fuming nitric acid (RFNA). 

All oxidizers being evaluated for use in rocket engines are carefully examined to determine their compatibility with the materials with which they will be in contact. In some cases elaborate steps are necessary to develop passivation techniques that permit extended storage of these oxidizers. One of the classical cases in recent years was the development of inhibited red fuming nitric acid (IRFNA) for use in aluminum tanks. 

IRFNA consists of concentrated nitric acid (HN03) that contains dissolved nitrogen dioxide and a small amount of fluoride ion, as hydrofluric acid (HF). 

MON and high density acid (HDA) are variants of storable oxidizers based on dinitrogen tetroxide. The MON propellants consist of N204 and NO, as noted earlier, and HDA is a mixture of nitric acid and N204. Both HDA and MON behave similarly to IRFNA. 

At this point, the more recent development of so-called gel propellants should be mentioned. We have seen above that for military missiles, hypergolicity is a desired property. On the other hand, transportation of IRFNA or NTO in combination with MMH or UDMH on a ship or submarine for example also carries high risks... 

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