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RP-1 (alternately, Rocket Propellant-1 or Refined Petroleum-1) is a highly refined form of kerosene outwardly similar to jet fuel, used as rocket fuel. Although having a lower specific impulse than liquid hydrogen (LH2), RP-1 is cheaper, stable at room temperature, far less of an explosion hazard and far denser. RP-1 is significantly more powerful than LH2 by volume. RP-1 also has a fraction of the toxicity and carcinogenic hazards of hydrazine, another room-temperature liquid fuel. Thus, kerosene fuels are more practical for many uses. ==Usage and history== RP-1 is most commonly burned with LOX (liquid oxygen) as the oxidizer, though other oxidizers have also been used. RP-1 is a fuel in the first-stage boosters of the Soyuz-FG, Zenit, Delta I-III, Atlas, Falcon 9, Antares and Tronador II rockets. It also powered the first stages of the Energia, Titan I, Saturn I and IB, and Saturn V. ISRO is also developing a RP-1 fueled engine for its future rockets.〔(Semi-cryogenic Project ) ISRO Annual Report 2013 - 2014〕 During and immediately after World War II, alcohols (primarily ethanol, occasionally methanol) were the single most common fuel for large liquid-fueled rockets. Its high heat of vaporization kept regeneratively cooled engines from melting, especially considering that alcohols would typically contain several percent water. However, it was recognized that hydrocarbon fuels would increase engine efficiency, due to a slightly higher density, the lack of an oxygen atom in the fuel molecule, and negligible water content. Whatever hydrocarbon was chosen, though, would have to replicate alcohol's coolant ability. Many early rockets had burned kerosene, but as burn times, combustion efficiencies, and combustion-chamber pressures grew, and as engine masses shrank, the engine temperatures became unmanageable. Raw kerosene used as coolant would dissociate and polymerize. Lightweight products in the form of gas bubbles, and heavy ones in the form of engine deposits, then blocked the narrow cooling passages. The coolant starvation raised temperatures further, accelerating breakdown. This cycle would escalate rapidly (i.e., thermal runaway would occur) until an engine wall ruptured. This occurred even with the entire flow of kerosene used as coolant. Rocket designers turned to the fuel chemists to formulate a heat-resistant hydrocarbon. The specification was completed in the mid-1950s. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「RP-1」の詳細全文を読む スポンサード リンク
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