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astronautix.com LF2/Hydrazine





Oxidiser: LF2. Oxidiser Density: 1.51 g/cc. Oxidiser Freezing Point: -219.00 deg C. Oxidiser Boiling Point: -188.00 deg C.

Liquid Fluorine is the highest performance oxidiser and in the early 1960's it seemed in both American and Russia that a new generation of higher performance engines would emerge. However although test engines were built, fluorine was found to be just too toxic and reactive to be safely used as a propellant. Liquid fluorine is essentially 100 per cent pure, containing only traces of oxygen, nitrogen, and hydrogen fluoride. The liquid exhibits a clear; yellow colour, while the gas has a pale greenish-yellow colour at ambient temperature. Fluorine is the strongest oxidising agent known. Under proper conditions, fluorine reacts with practically every element or compound except the inert gases. It is stable to shock, heat, and electric spark. It is non-flammable with air. Fluorine is highly toxic and irritating to all tissues. It has a characteristic pungent halogen odour and is irritating to the respiratory tract. Fluorine is produced from a molten mixture of HF and KF by an electrolytic procedure. The 1959 United. States production of liquid fluorine was estimated at 40,000 tonnes/year. Liquid fluorine's cost, ex-works, was then $ 6.00 per kg. In the Soviet Union Glushko founded a plant for production of fluorine propellants 23 km from Leningrad at Karlelsko. The population eventually reached 120,000, but although one engine was ready for production, this was never authorised due to the safety problems in case of a launch vehicle failure.


Fuel: Hydrazine. Fuel Density: 1.01 g/cc. Fuel Freezing Point: 2.00 deg C. Fuel Boiling Point: 113.00 deg C.

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.

Engines Using LF2/Hydrazine

Eng-engineslink Thrust(vac)-kgf Thrust(vac)-kN Isp-sec Isp (sea level)-sec Designed for Status
G-1 5,450 53.50 357   Upper Stages Developed 1960's
Chariot 15,900 155.90     Upper Stages Developed 1960's


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Last update 3 May 2001.
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© Mark Wade, 2001 .