Chlorine trifluoride was another of the extremely reactive and toxic oxidisers tested in the United States in the late 1950's. As in the other cases, it was found that the handling problems and safety risks outweighed the performance benefits. ClF3 is available commercially in purities of 99+ per cent ClF3. The most likely impurity is hydrogen fluoride. Chlorine trifluoride is a colorless gas at atmospheric pressure and temperature. The liquid has a pale green colour, while the solid is white. The odour of ClF3 has been described as both sweet and pungent, similar to chlorine or mustard. ClF3 is a toxic and corrosive oxidising agent similar to elemental fluorine in nature. It reacts with water. ClF3 is non-flammable with air, but will support combustion with almost all organic vapours and liquids. ClF3 reacts with every element except the rare gases, nitrogen, and possibly platinum and palladium. However, at low or intermediate temperatures, a protective fluoride film is formed on certain metal surfaces, which halts further reaction. Thus, metals such as mild steel, copper, brass, steel, Monel, and nickel may be used as materials of construction.
Chlorine trifluoride is prepared by direct combination of the elements. The 1959 ClF3 production capacity was 12 to 25 tonnes/year; this could be increased in six to eight months to 50 to 100 tonnes per year by enlarging halogen fluoride reactor capacity without incurring a shortage of fluorine. Quantities in excess of this amount would require a lead time of one year, and would involve construction of new fluorine facilities. The projected price of ClF3 $ 6.00 per kg at the existing rate.
In January 1953 Rocketdyne commenced the REAP program to develop a number of improvements to the engines being developed for the Navaho and Atlas missiles. Among these was development of a special grade of kerosene suitable for rocket engines. Prior to that any number of rocket propellants derived from petroleum had been used. Goddard had begun with gasoline, and there were experimental engines powered by kerosene, diesel oil, paint thinner, or jet fuel kerosene JP-4 or JP-5. The wide variance in physical properties among fuels of the same class led to the identification of narrow-range petroleum fractions, embodied in 1954 in the standard US kerosene rocket fuel RP-1, covered by Military Specification MIL-R-25576. In Russia, similar specifications were developed for kerosene under the specifications T-1 and RG-1. The Russians also developed a compound of unknown formulation in the 1980's known as 'Sintin', or synthetic kerosene. Rocket propellant RP-1 is a straight-run kerosene fraction, which is subjected to further treatment, i.e., acid washing, sulphur dioxide extraction. Thus, unsaturated substances which polymerise in storage are removed, as are sulphur-containing hydrocarbons. Furthermore, in order to meet specification requirements of density, heat of combustion, and aromatic content, the kerosene must be obtained from crudes with a high naphthene content. RP-1 is an excellent solvent for many organic materials. The flash point is above 43 deg C. Above that temperature RP-1 will form explosive mixtures with air. The temperature range for explosive mixtures (rich limit) is 79 to 85 deg C. RP-1 is not so toxic as the JP series of fuels because of its lower aromatic content. In the United States, suitable kerosene fractions in 1960 were limited almost exclusively to the West Coast. The estimated 1956 United States production was 7700 tonnes, and the price was $0.05 per kg. By the 1980's it was typically $ 0.20 per kg. Russian formulations have typical densities of 0.82 to 0.85 g/cc, and even higher densities were achieved in the N1 and Soyuz 11A511U rockets by superchilling the fuel prior to loading.