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badidea, madscience, propulsion, rocketry, spaceflight, whyyoudontgiveengineersfreetimeRocketdyne is notable among the space exploration set for developing a number of NASA's workhorse chemical rocket engines, such as the main thrusters of the Shuttle. But during the Space Race, they created a monster of such an engine, built around a tripropellant mix of molten lithium, liquid hydrogen, and liquid fluorine - an engine where the safest component was the asbestos cladding. (SLYT)
Needless to say, this engine never got off the testing frame for very obvious reasons. They even came up with a variant that added radioactive cesium to the lithium to keep it molten, fittingly named TOXMAX.