Encyclopedia Astronautica

CF2 was a free radical considered as a rocket oxidizer in the 1950's. It proved to unstable for use. Hydrazine (N2H4) found early use as a fuel, but it was quickly replaced by UDMH. It is still used as a monopropellant for satellite station-keeping motors.

Hydrazine marketed for rocket propellant contains a minimum of 97 per cent N2H4, the other constituent being primarily water. Hydrazine is a clear, water-white, hygroscopic liquid. The solid is white. Hydrazine a toxic, flammable caustic liquid and a strong reducing agent. Its odour is similar that of ammonia, though less strong. It is slightly soluble in ammonia and methyl-amine. It is soluble in water, methanol, ethanol, UDMH, and ethylenediamine. Hydrazine is manufactured by the Raschig process, which involves the oxidation of ammonia to chloramine, either indirectly with aqueous sodium hypochlorite or directly with chlorine, and subsequent reaction of chloramine with excess ammonia. Raw materials include caustic, ammonia, and chlorine; these are high-tonnage, heavy chemicals. The cost of anhydrous hydrazine in drum quantities in 1959 was $ 7.00 per kg. The projected price, based on large-scale commercial production, was expected to be $ 1.00 per kg. Due to environmental regulations, by 1990 NASA was paying $ 17.00 per kg.

Oxidizer: CF2. Fuel: Hydrazine. Propellant Formulation: CF2/Hydrazine. Optimum Oxidizer to Fuel Ratio: 1.5. Temperature of Combustion: 4,030 deg K. Density: 1.26 g/cc. Characteristic velocity c: 2,085 m/s (6,840 ft/sec). Isp Shifting: 345 sec. Isp Frozen: 321 sec. Oxidizer Density: 1.520 g/cc. Fuel Density: 1.008 g/cc. Fuel Freezing Point: 2.00 deg C. Fuel Boiling Point: 113 deg C.

Location: 2085.
Specific impulse: 321 s.

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