The LR91 was an American liquid-propellant rocket engine , which was used on the second stages of Titan intercontinental ballistic missiles and launch vehicles . While the original version - the LR91-3 - ran on RP-1 / LOX (as did the companion LR87-3 ) on the Titan I , the models that propelled the Titan II and later were switched to Aerozine 50 / N 2 O 4 .
4-605: This engine was vacuum optimized and ran the gas-generator cycle. The thrust chamber used fuel for regenerative cooling , with separate ablative skirt. The LR87 , which was used for the Titan first stage, was used as a template for the LR91. Early LR91 engines used on the Titan I burned RP-1 and liquid oxygen. Because liquid oxygen is cryogenic , it could not be stored in the missile for long periods of time, and had to be loaded before
8-467: Is one of the most commonly used power cycles in bipropellant liquid rocket engines. Propellant is burned in a gas generator (or "preburner") and the resulting hot gas is used to power the propellant pumps before being exhausted overboard and lost. Because of this loss, this type of engine is termed open cycle . The gas generator cycle exhaust products pass over the turbine first. Then they are expelled overboard. They can be expelled directly from
12-501: The missile could be launched. For the Titan II , the engine was converted to use Aerozine-50 and nitrogen tetroxide, which are hypergolic and storable at room temperature. This allowed Titan II missiles to be kept fully fueled and ready to launch on short notice. This rocketry article is a stub . You can help Misplaced Pages by expanding it . Gas-generator cycle (rocket) The gas-generator cycle , also called open cycle ,
16-437: The turbine, or are sometimes expelled into the nozzle (downstream from the throat) for a small gain in efficiency. The main combustion chamber does not use these products. This explains the name of the open cycle. The major disadvantage is that this propellant contributes little to no thrust because they are not injected into the combustion chamber. The major advantage of the cycle is reduced engineering complexity compared to
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