| > I suspect their primary advantage remains shelf-stability at room temperatures, which will make them stay relevant for military applications I while ago I read--but barely understood--a book that went into a lot of this: "Ignition! An Informal History of Liquid Rocket Propellants" by John D. Clark. _____________________ IIRC there were some cases where a fuel was not militarily-acceptable because you would need to warm/thaw the mobile missile prior to firing in a Russian winter, or other cases where a permanent missile-silo meant it was cost-effective to run heating/refrigeration all the time, etc. > [I]n applications which do not require a low freezing point, hydrazine itself is fused, either straight or mixed with one of its derivatives. The fuel of the Titan II ICBM doesn't have to have a low freezing point, since Titan II lives in a steam-heated hole in the ground, but it does need the highest possible performance, and hydrazine was the first candidate for the job. _____________________ Another fuel-choice issue involves how badly it might self-destruct if anything unusual happened: > [I]n the summer of 1960, we tried to fire a 10,000-pound thrust Cavea B motor. [...] Well, through a combination of this and that, the motor blew on startup. We never discovered whether or not the [detonation] traps worked—we
couldn't find enough fragments to find out. > The fragments from the injector just short-circuited the traps, smashed into the tank, and set off the 200 pounds of propellant in that. (Each pound of propellant had more available energy than two pounds of TNT.) I never saw
such a mess. The walls of the test cell—two feet of concrete—went out, and the roof came in. The motor itself—a heavy, workhorse job of solid copper— went about 600 feet down range. And a six-foot square of armor plate sailed into the woods, cutting off a few trees at the root, smashing a granite boulder, bouncing into the air and slicing off a few
treetops, and finally coming to rest some 1400 feet from where it started. The woods looked as though a stampeding herd of wild elephants had been through. > As may be imagined, this incident tended to give monopropellants something of a bad name. Even if you could fire them safely—and we soon saw what had gone wrong with the ignition process—how could you use them in the field? > Here you have a rocket set up on the launching stand, under battlefield conditions; and what happens if it gets hit by a piece of shrapnel? LRPL came up with the answer to that. You keep your monoprop in the missile in two compartments: one full of fuel-rich propellant made up to A. = 2.2 or 2.4, and the other containing enough acid to dilute it to X = 1.2. Just before you fire, a can-opener arrangement inside the missile slits open the barrier separating the two liquids, you allow a few seconds for them to mix,
and then push the button. |